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TDMS Study 05185-03 Pathology Tables

NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48




       Facility:  I. I. T. Research Institute

       Chemical CAS #:  542-56-3

       Lock Date:  05/22/92

       Cage Range:  All

       Reasons For Removal:    All

       Removal Date Range:     All

       Treatment Groups:       Include All






































                                                              Page   1

NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 7| 7| 7| 6| 6| 7| 7| 7| 7| 7| 6| 5| 6| 6| 7| 7| 6| 6| 7| 7| 7| 7| 7|             
                             DAY ON TEST   | 3| 3| 3| 3| 3| 5| 6| 3| 3| 3| 3| 3| 0| 1| 4| 5| 3| 3| 4| 7| 3| 3| 3| 0| 3|             
                                           | 3| 4| 3| 3| 4| 2| 8| 4| 5| 3| 5| 4| 2| 6| 1| 8| 5| 4| 6| 1| 5| 5| 5| 2| 4|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    CONTROL                                | 5| 5| 5| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8|             
                                           | 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation                         |                                              4                           |             
      Necrosis                             |                                              4                           |             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation                         |                      2                                                   |             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Basophilic Focus                     |                                  1                                       |             
      Basophilic Focus, Multiple           | 2     2  1  2        2  2  2  2     2           2  2        2  2  2     1|             
      Clear Cell Focus                     |                                                                          |             
      Congestion                           |                                                                          |             
      Developmental Malformation           |                               2                                          |             
      Eosinophilic Focus                   |                                                                          |             
      Fatty Change                         |                4        2  2  2           1           3                  |             
      Hematopoietic Cell Proliferation     |                                                                1         |             
      Hemorrhage                           |                                                                          |             
      Hepatodiaphragmatic Nodule           |                                  X                          X            |             
      Inflammation                         |                         1                                                |             
      Mixed Cell Focus                     |                                                                          |             
      Necrosis                             |                      2                                         2         |             
                                            __________________________________________________________________________|             
   Mesentery                               |                                                 +                        |             
      Fat, Necrosis                        |                                                 3                        |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Accessory Spleen                     |                                                                          |             
      Acinar Cell, Atrophy                 |          1                    2     1           1        2  2     2  1  2|             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                2                                         2               |             
      Ulcer                                |                   3                                      1               |             
      Ulcer, Multiple                      |                                                                      2   |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation                         |                                                                          |             
      Ulcer                                |                                              3                       2   |             
      Ulcer, Multiple                      |                   3                                                      |             
                                            __________________________________________________________________________|             
   Tongue                                  |                                        +                                 |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       | 1        1  1  1  1     1  1     1  1     1     1  1        2  1  2      |             
      Atrium, Thrombosis                   |    3                                                                 2   |             
 _____________________________________________________________________________________________________________________|             
                                                             Page   2                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 7| 7| 7| 6| 6| 7| 7| 7| 7| 7| 6| 5| 6| 6| 7| 7| 6| 6| 7| 7| 7| 7| 7|             
                             DAY ON TEST   | 3| 3| 3| 3| 3| 5| 6| 3| 3| 3| 3| 3| 0| 1| 4| 5| 3| 3| 4| 7| 3| 3| 3| 0| 3|             
                                           | 3| 4| 3| 3| 4| 2| 8| 4| 5| 3| 5| 4| 2| 6| 1| 8| 5| 4| 6| 1| 5| 5| 5| 2| 4|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    CONTROL                                | 5| 5| 5| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8|             
                                           | 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1|             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM - cont              |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                  1              2                        |             
      Cyst                                 |                                     3                                    |             
      Degeneration                         |                                                                          |             
      Hemorrhage                           |                                                                          |             
      Hyperplasia                          |                      1           1                                       |             
      Hypertrophy                          |       1                                                                  |             
      Necrosis                             |                                                                          |             
      Vacuolization Cytoplasmic            | 1     1                                                                 2|             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Hyperplasia                          |                                     1                                    |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      |                   +     +              +  +                       +      |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  M  +  +  +  +  M  +|             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                   2                          2                       3   |             
      Hyperplasia                          |                                              3                           |             
      Pars Distalis, Angiectasis           |                                        1           3     4              2|             
      Pars Distalis, Cyst                  |          2  2        3           2     2           2              2      |             
      Pars Distalis, Hyperplasia           |                                                    3                     |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  |             2                       2                 2        1        2|             
      Follicle, Dilatation                 |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Clitoral Gland                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Ectasia                              |    2  1        2  3  3        2              3     2  3        2     3  2|             
      Hyperplasia                          |                      2                                      2            |             
      Inflammation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |    3  3                                                                  |             
      Corpus Luteum, Hyperplasia           |                                              3                           |             
                                            __________________________________________________________________________|             
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Dilatation                           |                                                                          |             
      Hemorrhage                           |                                                                          |             
      Bilateral, Dilatation                |                                                                   2      |             
      Endometrium, Hyperplasia             |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page   3                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 7| 7| 7| 6| 6| 7| 7| 7| 7| 7| 6| 5| 6| 6| 7| 7| 6| 6| 7| 7| 7| 7| 7|             
                             DAY ON TEST   | 3| 3| 3| 3| 3| 5| 6| 3| 3| 3| 3| 3| 0| 1| 4| 5| 3| 3| 4| 7| 3| 3| 3| 0| 3|             
                                           | 3| 4| 3| 3| 4| 2| 8| 4| 5| 3| 5| 4| 2| 6| 1| 8| 5| 4| 6| 1| 5| 5| 5| 2| 4|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    CONTROL                                | 5| 5| 5| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8|             
                                           | 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                  1  4     3                    4         |             
                                            __________________________________________________________________________|             
   Lymph Node                              |                                                                          |             
      Lumbar, Cyst                         |                                                                          |             
      Lumbar, Hyperplasia, Lymphoid        |                                                                          |             
      Lumbar, Pigmentation                 |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Bronchial                   | +  +  +  M  M  M  +  M  M  +  +  M  M  +  M     +  +  M  M  +  M  M  +  M|             
      Hemorrhage                           |                               3                             1            |             
      Pigmentation                         |                                                                      2   |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                                                          |             
      Hyperplasia, Plasma Cell             |                3                                                         |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Edema                                |                                                                          |             
      Hemorrhage                           |          1  3                 2           1           1        3         |             
      Pigmentation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mediastinal                 | +  +  +  +  +  +  +  +  M  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |       2  1  3  1  2  2     3  3  2  3     1     1           2  3  2     2|             
      Infiltration Cellular, Histiocyte    |                                                                3         |             
      Pigmentation                         |       1  2     2     2     2              1           2        2  2  2  2|             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hematopoietic Cell Proliferation     |                                     3                          2         |             
      Pigmentation                         |                                        3                                 |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |       1  2     4  4     2  4  2  3  2  4  4  3  1  2        1  3     3   |             
      Pigmentation                         |                                                                      2   |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Lactation                            |       2        1        3           2     2     3  2  3        2     2   |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Tail, Hyperkeratosis                 |                                                                          |             
      Tail, Parakeratosis                  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Compression                          |                3        2  1              2     2     3  3               |             
      Hemorrhage                           |                                                                          |             
      Hydrocephalus                        |                         3                                      1         |             
      Thrombosis                           |                                                       3                  |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page   4                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 7| 7| 7| 6| 6| 7| 7| 7| 7| 7| 6| 5| 6| 6| 7| 7| 6| 6| 7| 7| 7| 7| 7|             
                             DAY ON TEST   | 3| 3| 3| 3| 3| 5| 6| 3| 3| 3| 3| 3| 0| 1| 4| 5| 3| 3| 4| 7| 3| 3| 3| 0| 3|             
                                           | 3| 4| 3| 3| 4| 2| 8| 4| 5| 3| 5| 4| 2| 6| 1| 8| 5| 4| 6| 1| 5| 5| 5| 2| 4|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    CONTROL                                | 5| 5| 5| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8|             
                                           | 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1|             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM - cont                 |                                                                          |             
                                           |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation                         |                                        3                                 |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                        1           1                     |             
      Infiltration Cellular, Histiocyte    |                                                                      1   |             
      Inflammation                         |                            1  1                                          |             
      Alveolar Epithelium, Hyperplasia     |       1                                            2                     |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Foreign Body                         |                      2           1                                       |             
      Inflammation                         |                      2           2                                      1|             
      Goblet Cell, Hyperplasia             |                                                                          |             
      Nasolacrimal Duct, Inflammation      |                         3                                                |             
      Olfactory Epithelium, Cytoplasmic    |                                                                          |             
          Alteration                       |                                                                          |             
      Respiratory Epithelium, Hyperplasia  |                         2     2  1                                       |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                                          |             
      Infarct                              |                                              3                           |             
      Mineralization                       |                                        1              1                  |             
      Nephropathy, Chronic                 | 2  1  2  1  2  1  2  1  3  2  3  2  1     2     2  2  2  2  1     1  1  2|             
      Pigmentation                         |                                                                      1   |             
      Transitional Epithelium, Hyperplasia |                                                                          |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Dilatation                           |                3                                                         |             
 _____________________________________________________________________________________________________________________|             
                                                             Page   5                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 7| 5| 7| 7| 7| 7| 7| 7| 7| 7| 6| 7| 6| 6| 7| 4| 7| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 0| 3| 3| 2| 2| 3| 3| 3| 3| 3| 3| 3| 4| 3| 4| 6| 3| 6| 2| 3| 3| 5| 5| 5| 5|             
                                           | 4| 5| 3| 6| 1| 3| 4| 4| 3| 5| 4| 3| 0| 3| 0| 6| 5| 4| 0| 4| 3| 7| 7| 7| 7|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1|             
    CONTROL                                | 8| 8| 8| 8| 8| 8| 8| 8| 9| 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0|             
                                           | 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  A  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation                         |                                                                          |             
      Necrosis                             |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Basophilic Focus                     |             2                             1              1           1  1|             
      Basophilic Focus, Multiple           |    1  2                 2  2           1        1           1            |             
      Clear Cell Focus                     |                1  1     1                                                |             
      Congestion                           |             1                                                            |             
      Developmental Malformation           |                                           2                              |             
      Eosinophilic Focus                   |                                                             2            |             
      Fatty Change                         | 2     1                             3              2                     |             
      Hematopoietic Cell Proliferation     |                                                                   1      |             
      Hemorrhage                           |                                                                          |             
      Hepatodiaphragmatic Nodule           |             X                                                            |             
      Inflammation                         |                                                    2                     |             
      Mixed Cell Focus                     |                2        X                                                |             
      Necrosis                             |                                  1                                       |             
                                            __________________________________________________________________________|             
   Mesentery                               |                                                                          |             
      Fat, Necrosis                        |                                                                          |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Accessory Spleen                     |                   X                                                      |             
      Acinar Cell, Atrophy                 |             2     1     1  2                 1     1     2  2            |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                                                          |             
      Ulcer                                |                                                       2                  |             
      Ulcer, Multiple                      |                                                    3                     |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation                         |                                     2                                    |             
      Ulcer                                |                                                                          |             
      Ulcer, Multiple                      |                                                                          |             
                                            __________________________________________________________________________|             
   Tongue                                  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       | 1  1  1  1     1  1        1           1  1     1  1  2  1  1     1  1  1|             
      Atrium, Thrombosis                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page   6                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 7| 5| 7| 7| 7| 7| 7| 7| 7| 7| 6| 7| 6| 6| 7| 4| 7| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 0| 3| 3| 2| 2| 3| 3| 3| 3| 3| 3| 3| 4| 3| 4| 6| 3| 6| 2| 3| 3| 5| 5| 5| 5|             
                                           | 4| 5| 3| 6| 1| 3| 4| 4| 3| 5| 4| 3| 0| 3| 0| 6| 5| 4| 0| 4| 3| 7| 7| 7| 7|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1|             
    CONTROL                                | 8| 8| 8| 8| 8| 8| 8| 8| 9| 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0|             
                                           | 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6|             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM - cont              |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                             1            |             
      Cyst                                 |                                                                          |             
      Degeneration                         |    2                                                                     |             
      Hemorrhage                           |                   3                                                      |             
      Hyperplasia                          | 2           2                                            1               |             
      Hypertrophy                          |                                                                          |             
      Necrosis                             |                                     3                                    |             
      Vacuolization Cytoplasmic            |             2                    3     2     1  1                        |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Hyperplasia                          |                                                       2                  |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      |                               +                                          |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  M  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                                          |             
      Hyperplasia                          |                                                                          |             
      Pars Distalis, Angiectasis           |       2        4     3                                      3        2   |             
      Pars Distalis, Cyst                  |    2              1  2     2           1                 3     2         |             
      Pars Distalis, Hyperplasia           |       1                          2  3        1  2                    3   |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  |       2        2                                                        2|             
      Follicle, Dilatation                 |             2                                                            |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Clitoral Gland                          | +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  M  +  +  +  +  +  +  +  +  +|             
      Ectasia                              |    3  1  1  2  1     2  3  2  3        1  2     3  2           2  2     3|             
      Hyperplasia                          |                                                                          |             
      Inflammation                         |    2                                                              1      |             
                                            __________________________________________________________________________|             
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                           1              2  2            |             
      Corpus Luteum, Hyperplasia           |                                                                          |             
                                            __________________________________________________________________________|             
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Dilatation                           |                      3                                                   |             
      Hemorrhage                           |                                                                      4   |             
      Bilateral, Dilatation                |                               3                                          |             
      Endometrium, Hyperplasia             |                2                                                         |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page   7                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 7| 5| 7| 7| 7| 7| 7| 7| 7| 7| 6| 7| 6| 6| 7| 4| 7| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 0| 3| 3| 2| 2| 3| 3| 3| 3| 3| 3| 3| 4| 3| 4| 6| 3| 6| 2| 3| 3| 5| 5| 5| 5|             
                                           | 4| 5| 3| 6| 1| 3| 4| 4| 3| 5| 4| 3| 0| 3| 0| 6| 5| 4| 0| 4| 3| 7| 7| 7| 7|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1|             
    CONTROL                                | 8| 8| 8| 8| 8| 8| 8| 8| 9| 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0|             
                                           | 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                     2        3                       1   |             
                                            __________________________________________________________________________|             
   Lymph Node                              |                   +                                                      |             
      Lumbar, Cyst                         |                   2                                                      |             
      Lumbar, Hyperplasia, Lymphoid        |                   2                                                      |             
      Lumbar, Pigmentation                 |                   2                                                      |             
                                            __________________________________________________________________________|             
   Lymph Node, Bronchial                   | +  +  M  +  +  M  +  +  +  M  +  +  +  M  +  +  +  +  M  M  +  +  +  +  +|             
      Hemorrhage                           |                   1                             2                 3     2|             
      Pigmentation                         |                                                                2         |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |             2                          1                                 |             
      Hyperplasia, Plasma Cell             |                                                       3                  |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Edema                                |    3                                                                     |             
      Hemorrhage                           |                   2                 2                                    |             
      Pigmentation                         |                      1                                                   |             
                                            __________________________________________________________________________|             
   Lymph Node, Mediastinal                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           | 2  2  1     3     4     1     1        2        2        1  2  1  3  1  2|             
      Infiltration Cellular, Histiocyte    |                                                                          |             
      Pigmentation                         | 2  2  2                 2     2  1  2  2  2                 2  2         |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hematopoietic Cell Proliferation     |    1                                3              2                     |             
      Pigmentation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              | 3  2  1        2  1  2  1  1  2  1  3  1  2  2  2  1  4  1  2  2  1  2  2|             
      Pigmentation                         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Lactation                            |    3                 3     2              2  3     2        1            |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Tail, Hyperkeratosis                 |                                  3                                       |             
      Tail, Parakeratosis                  |                                  2                                       |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Compression                          |    2        2  3     1                    2        3                     |             
      Hemorrhage                           |             2                             1                              |             
      Hydrocephalus                        |                                           2                              |             
      Thrombosis                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page   8                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 7| 5| 7| 7| 7| 7| 7| 7| 7| 7| 6| 7| 6| 6| 7| 4| 7| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 0| 3| 3| 2| 2| 3| 3| 3| 3| 3| 3| 3| 4| 3| 4| 6| 3| 6| 2| 3| 3| 5| 5| 5| 5|             
                                           | 4| 5| 3| 6| 1| 3| 4| 4| 3| 5| 4| 3| 0| 3| 0| 6| 5| 4| 0| 4| 3| 7| 7| 7| 7|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1|             
    CONTROL                                | 8| 8| 8| 8| 8| 8| 8| 8| 9| 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0|             
                                           | 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6|             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM - cont                 |                                                                          |             
                                           |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation                         |                      1                                               1   |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |    1                                      2              2        2      |             
      Infiltration Cellular, Histiocyte    |                                                                          |             
      Inflammation                         |                                  1  3                                    |             
      Alveolar Epithelium, Hyperplasia     |                                                             1            |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Foreign Body                         |                                                                          |             
      Inflammation                         |    2                 2        1              2                           |             
      Goblet Cell, Hyperplasia             |                                                                   2      |             
      Nasolacrimal Duct, Inflammation      |                                                             1            |             
      Olfactory Epithelium, Cytoplasmic    |                                                                          |             
          Alteration                       |                                                             2            |             
      Respiratory Epithelium, Hyperplasia  |                                                                          |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                              3                           |             
      Infarct                              |                                                                          |             
      Mineralization                       | 1                                                  1           1  1  1  1|             
      Nephropathy, Chronic                 | 2  1  1  1  2  2  2  1  2  1  1  2  2  1  2  2  1  3  1  1  2  2  1  1  1|             
      Pigmentation                         |                                     3                 1                  |             
      Transitional Epithelium, Hyperplasia |                2                                                         |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Dilatation                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page   9                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 7| 7| 7| 7| 7| 7|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1|                                                        |      A     |
    CONTROL                                | 0| 0| 0| 1| 1| 1|                                                        |      L     |
                                           | 7| 8| 9| 0| 1| 2|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM                         |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Esophagus                               | +  +  +  +  +  +                                                         |  55        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  +                                                         |  56        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +                                                         |  54        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  +  +  +                                                         |  56        |
      Inflammation                         |                                                                          |      1  4.0|
      Necrosis                             |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  +  +                                                         |  56        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  +  +  +                                                         |  54        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  +  +  +  +                                                         |  54        |
      Inflammation                         |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +                                                         |  56        |
      Basophilic Focus                     |                1                                                         |      7  1.1|
      Basophilic Focus, Multiple           |                                                                          |     22  1.7|
      Clear Cell Focus                     |                                                                          |      3  1.0|
      Congestion                           |                                                                          |      1  1.0|
      Developmental Malformation           |                                                                          |      2  2.0|
      Eosinophilic Focus                   |                                                                          |      1  2.0|
      Fatty Change                         |                                                                          |     10  2.2|
      Hematopoietic Cell Proliferation     |    1  1                                                                  |      4  1.0|
      Hemorrhage                           |             1                                                            |      1  1.0|
      Hepatodiaphragmatic Nodule           |                                                                          |      3     |
      Inflammation                         |    1           1                                                         |      4  1.3|
      Mixed Cell Focus                     |                                                                          |      2  2.0|
      Necrosis                             |                                                                          |      3  1.7|
                                            __________________________________________________________________________|____________|
   Mesentery                               |                                                                          |   1        |
      Fat, Necrosis                        |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +                                                         |  56        |
      Accessory Spleen                     |                                                                          |      1     |
      Acinar Cell, Atrophy                 | 1     1                                                                  |     19  1.5|
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +                                                         |  56        |
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +                                                         |  56        |
      Hyperplasia                          |                                                                          |      2  2.0|
      Ulcer                                |                                                                          |      3  2.0|
      Ulcer, Multiple                      |                                                                          |      2  2.5|
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +                                                         |  56        |
      Inflammation                         |                                                                          |      1  2.0|
      Ulcer                                |                                                                          |      2  2.5|
      Ulcer, Multiple                      |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Tongue                                  |                                                                          |   1        |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  10                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 7| 7| 7| 7| 7| 7|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1|                                                        |      A     |
    CONTROL                                | 0| 0| 0| 1| 1| 1|                                                        |      L     |
                                           | 7| 8| 9| 0| 1| 2|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM - cont                  |                                                                          |            |
                                           |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +                                                         |  56        |
      Cardiomyopathy                       | 1  1  1  1  1  1                                                         |     38  1.1|
      Atrium, Thrombosis                   |                                                                          |      2  2.5|
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +                                                         |  56        |
      Angiectasis                          |          2                                                               |      4  1.5|
      Cyst                                 |                                                                          |      1  3.0|
      Degeneration                         |                                                                          |      1  2.0|
      Hemorrhage                           |                                                                          |      1  3.0|
      Hyperplasia                          |                                                                          |      5  1.4|
      Hypertrophy                          |                                                                          |      1  1.0|
      Necrosis                             |                                                                          |      1  3.0|
      Vacuolization Cytoplasmic            |                                                                          |      8  1.6|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +                                                         |  55        |
      Angiectasis                          |          2                                                               |      1  2.0|
      Hyperplasia                          |                                                                          |      2  1.5|
                                            __________________________________________________________________________|____________|
   Islets, Pancreatic                      |                                                                          |   6        |
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | +  +  +  +  +  +                                                         |  51        |
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +                                                         |  56        |
      Cyst                                 |                                                                          |      3  2.3|
      Hyperplasia                          |                                                                          |      1  3.0|
      Pars Distalis, Angiectasis           |          3  2                                                            |     11  2.6|
      Pars Distalis, Cyst                  | 1  2                                                                     |     16  1.9|
      Pars Distalis, Hyperplasia           |             3  2                                                         |      9  2.2|
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +                                                         |  56        |
      C-Cell, Hyperplasia                  |                                                                          |      8  1.9|
      Follicle, Dilatation                 |                                                                          |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Clitoral Gland                          | +  +  +  +  +  +                                                         |  54        |
      Ectasia                              | 2  3  2  2                                                               |     32  2.2|
      Hyperplasia                          |                                                                          |      2  2.0|
      Inflammation                         |                                                                          |      2  1.5|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  11                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 7| 7| 7| 7| 7| 7|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1|                                                        |      A     |
    CONTROL                                | 0| 0| 0| 1| 1| 1|                                                        |      L     |
                                           | 7| 8| 9| 0| 1| 2|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 GENITAL SYSTEM - cont                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Ovary                                   | +  +  +  +  +  +                                                         |  56        |
      Cyst                                 |                                                                          |      5  2.2|
      Corpus Luteum, Hyperplasia           |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Uterus                                  | +  +  +  +  +  +                                                         |  56        |
      Dilatation                           |                                                                          |      1  3.0|
      Hemorrhage                           |                                                                          |      1  4.0|
      Bilateral, Dilatation                |                                                                          |      2  2.5|
      Endometrium, Hyperplasia             |                                                                          |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +                                                         |  56        |
      Hyperplasia                          |                                                                          |      7  2.6|
                                            __________________________________________________________________________|____________|
   Lymph Node                              |                                                                          |   1        |
      Lumbar, Cyst                         |                                                                          |      1  2.0|
      Lumbar, Hyperplasia, Lymphoid        |                                                                          |      1  2.0|
      Lumbar, Pigmentation                 |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Bronchial                   | +  +  +  +  +  +                                                         |  36        |
      Hemorrhage                           | 2  2  1  1  1  2                                                         |     12  1.8|
      Pigmentation                         |                                                                          |      2  2.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +                                                         |  55        |
      Hemorrhage                           |                                                                          |      2  1.5|
      Hyperplasia, Plasma Cell             |                                                                          |      2  3.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +                                                         |  56        |
      Edema                                |                                                                          |      1  3.0|
      Hemorrhage                           |                                                                          |      8  1.9|
      Pigmentation                         |                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mediastinal                 | +  +  +  +  +  +                                                         |  54        |
      Hemorrhage                           | 1  2  2  2  2  1                                                         |     37  1.9|
      Infiltration Cellular, Histiocyte    |                                                                          |      1  3.0|
      Pigmentation                         |                                                                          |     22  1.9|
                                            __________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +                                                         |  56        |
      Hematopoietic Cell Proliferation     |                                                                          |      5  2.2|
      Pigmentation                         |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Thymus                                  | +  +  +  +  +  +                                                         |  54        |
      Atrophy                              | 2  2  2  1                                                               |     44  2.1|
      Pigmentation                         |                                                                          |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Mammary Gland                           | +  +  +  +  +  +                                                         |  56        |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  12                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 7| 7| 7| 7| 7| 7|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1|                                                        |      A     |
    CONTROL                                | 0| 0| 0| 1| 1| 1|                                                        |      L     |
                                           | 7| 8| 9| 0| 1| 2|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 INTEGUMENTARY SYSTEM - cont               |                                                                          |            |
                                           |                                                                          |            |
      Lactation                            |                                                                          |     17  2.2|
                                            __________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +                                                         |  56        |
      Tail, Hyperkeratosis                 |                                                                          |      1  3.0|
      Tail, Parakeratosis                  |                                                                          |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +                                                         |  56        |
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +                                                         |  56        |
      Compression                          |                                                                          |     13  2.2|
      Hemorrhage                           |                                                                          |      2  1.5|
      Hydrocephalus                        |                                                                          |      3  2.0|
      Thrombosis                           |                                                                          |      1  3.0|
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Larynx                                  | +  +  +  +  +  +                                                         |  56        |
      Inflammation                         |                                                                          |      3  1.7|
                                            __________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +                                                         |  56        |
      Hemorrhage                           | 1     2  1     1                                                         |     10  1.4|
      Infiltration Cellular, Histiocyte    |                                                                          |      1  1.0|
      Inflammation                         |                                                                          |      4  1.5|
      Alveolar Epithelium, Hyperplasia     |                1                                                         |      4  1.3|
                                            __________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +                                                         |  56        |
      Foreign Body                         |                                                                          |      2  1.5|
      Inflammation                         |                                                                          |      7  1.7|
      Goblet Cell, Hyperplasia             |                                                                          |      1  2.0|
      Nasolacrimal Duct, Inflammation      |                                                                          |      2  2.0|
      Olfactory Epithelium, Cytoplasmic    |                                                                          |            |
          Alteration                       |                2                                                         |      2  2.0|
      Respiratory Epithelium, Hyperplasia  |                                                                          |      3  1.7|
                                            __________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +                                                         |  56        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +                                                         |  56        |
      Cyst                                 |                                                                          |      1  3.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  13                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 7| 7| 7| 7| 7| 7|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1|                                                        |      A     |
    CONTROL                                | 0| 0| 0| 1| 1| 1|                                                        |      L     |
                                           | 7| 8| 9| 0| 1| 2|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 URINARY SYSTEM - cont                     |                                                                          |            |
                                           |                                                                          |            |
      Infarct                              |                                                                          |      1  3.0|
      Mineralization                       | 1  1  1  1  1  1                                                         |     14  1.0|
      Nephropathy, Chronic                 | 1  1  1     1  1                                                         |     52  1.6|
      Pigmentation                         |                                                                          |      3  1.7|
      Transitional Epithelium, Hyperplasia |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  +  +  +                                                         |  56        |
      Dilatation                           |                                                                          |      1  3.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  14                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 7| 7| 6| 7| 6| 7| 7| 7| 7| 3| 6| 7| 4| 7| 6| 7| 7| 7| 1| 6| 7| 7| 7|             
                             DAY ON TEST   | 3| 3| 3| 3| 5| 2| 4| 3| 3| 3| 3| 7| 4| 3| 7| 3| 7| 3| 3| 3| 7| 2| 3| 3| 3|             
                                           | 3| 4| 3| 5| 9| 0| 8| 4| 4| 4| 5| 8| 5| 4| 7| 4| 2| 3| 3| 3| 6| 4| 3| 5| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    37.5 PPM                               | 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9| 9| 9| 9|             
                                           | 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +     +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  A  +  +  +  +  +  +  +  A  +  +  +  +  +     +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +     A  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  A  A  A  +  +  +  +  +  +  +  +  +  +  +  +  +     A  +  +  +|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
      Angiectasis                          |                                                          2               |             
      Basophilic Focus                     |                                        1                       1         |             
      Basophilic Focus, Multiple           | 2  2  2  2     2  2  2  2  2  2                 3  1  2  2        2  3  2|             
      Clear Cell Focus                     |    1                                                                     |             
      Eosinophilic Focus                   |                2              1        1                             3   |             
      Fatty Change                         |                                                          2     1         |             
      Hepatodiaphragmatic Nodule           |                      2                                                   |             
      Infiltration Cellular, Lymphocyte    |                                                                          |             
      Inflammation                         |                                                    1  1                  |             
      Necrosis                             |                                                                          |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
      Infiltration Cellular, Lymphocyte    |                                                                          |             
      Acinar Cell, Atrophy                 |    2     1     4  1        1  2     1     2        2     3        1     2|             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
      Inflammation                         |                      4                                                   |             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
      Inflammation                         |             1                                                            |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +     +  +  +  +|             
                                            __________________________________________________________________________|             
   Tongue                                  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
      Cardiomyopathy                       |                   2     1  1  2        1  2  1     2           1  1     1|             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
      Angiectasis                          |                         1  1        2                             2  2   |             
      Cytoplasmic Alteration               |                                                                          |             
      Degeneration                         |                                                                          |             
      Hemorrhage                           |                                                                          |             
      Hyperplasia                          |                            2                                         2   |             
      Hypertrophy                          |                                                                          |             
      Vacuolization Cytoplasmic            |          2                 2                 2  2  2                     |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
      Hyperplasia                          |                                                                         1|             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      |                                                                      +   |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  15                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 7| 7| 6| 7| 6| 7| 7| 7| 7| 3| 6| 7| 4| 7| 6| 7| 7| 7| 1| 6| 7| 7| 7|             
                             DAY ON TEST   | 3| 3| 3| 3| 5| 2| 4| 3| 3| 3| 3| 7| 4| 3| 7| 3| 7| 3| 3| 3| 7| 2| 3| 3| 3|             
                                           | 3| 4| 3| 5| 9| 0| 8| 4| 4| 4| 5| 8| 5| 4| 7| 4| 2| 3| 3| 3| 6| 4| 3| 5| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    37.5 PPM                               | 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9| 9| 9| 9|             
                                           | 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3|             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM - cont                   |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  M  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +     +  +  +  +|             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +     +  +  M  +|             
      Pars Distalis, Angiectasis           |          2           3  2              3     4                    2      |             
      Pars Distalis, Cyst                  | 2     1  3           2  2  1  3                          2        2      |             
      Pars Distalis, Hyperplasia           |                      2  2     2  2     3     2  2        3              2|             
      Pars Nervosa, Developmental          |                                                                          |             
          Malformation                     |          2                                                               |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
      C-Cell, Hyperplasia                  |                                                                         3|             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Tissue NOS                              |                   +                                                      |             
      Developmental Malformation           |                   X                                                      |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Clitoral Gland                          | +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
      Abscess                              | 3                                                                        |             
      Ectasia                              | 2  3     2     2        2  2  3  2  2        2  3        2              2|             
      Hyperplasia                          |                      2                                               3   |             
      Inflammation                         |                      3                                                   |             
                                            __________________________________________________________________________|             
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
      Cyst                                 |                         2                                         2      |             
      Bilateral, Cyst                      |                                                                          |             
                                            __________________________________________________________________________|             
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
      Cyst                                 |          2                                                               |             
      Dilatation                           |       2                                                                  |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
      Hyperplasia                          |                      2           2  3           3                 1      |             
      Myelofibrosis                        |                                                          2               |             
                                            __________________________________________________________________________|             
   Lymph Node                              |                                  +                                       |             
      Axillary, Hyperplasia, Lymphoid      |                                  3                                       |             
      Axillary, Hyperplasia, Plasma Cell   |                                  2                                       |             
                                            __________________________________________________________________________|             
   Lymph Node, Bronchial                   | M  +  M  +  +  M  +  M  +  +  +  +  M  +  +  +  M  +  +  +     M  +  M  +|             
      Hemorrhage                           |    1     1                    2        1                 3        1      |             
      Pigmentation                         |                               2                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
      Cyst                                 |                                                                          |             
      Hemorrhage                           |                                                                          |             
      Hyperplasia, Lymphoid                |                      2                                                   |             
      Hyperplasia, Plasma Cell             |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
      Hemorrhage                           |    2  1                    1                 1                    1      |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  16                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 7| 7| 6| 7| 6| 7| 7| 7| 7| 3| 6| 7| 4| 7| 6| 7| 7| 7| 1| 6| 7| 7| 7|             
                             DAY ON TEST   | 3| 3| 3| 3| 5| 2| 4| 3| 3| 3| 3| 7| 4| 3| 7| 3| 7| 3| 3| 3| 7| 2| 3| 3| 3|             
                                           | 3| 4| 3| 5| 9| 0| 8| 4| 4| 4| 5| 8| 5| 4| 7| 4| 2| 3| 3| 3| 6| 4| 3| 5| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    37.5 PPM                               | 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9| 9| 9| 9|             
                                           | 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mediastinal                 | +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +     +  +  +  +|             
      Hemorrhage                           |    2  2  1     2  2        2  3        2  3  2     2  2  2     2     1  1|             
      Pigmentation                         | 1  2  1  2     1        1  2           2  3  2     2  2  2           1  2|             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
      Hematopoietic Cell Proliferation     |                                     2           2        2     2     3   |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  M  +     +  +  +  +|             
      Atrophy                              |    2              2     2  2  1     2     2  1  1  1     2        2     2|             
      Hemorrhage                           |                                           2                              |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
      Abscess                              |                                                                          |             
      Hemorrhage                           |                                                    2                     |             
      Lactation                            |                         2                                      2         |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
      Ulcer                                |                                                                          |             
      Ulcer, Multiple                      |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
      Femur, Hyperostosis                  |       3           3                                      3           3   |             
      Turbinate, Hyperostosis              |       3                                                              2   |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
      Compression                          |                   2                    2                       3         |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
      Congestion                           |                3  3                       2                    2         |             
      Hemorrhage                           |          1     3  1                 2     1     1              1     1   |             
      Infiltration Cellular, Histiocyte    |                   1                                                      |             
      Inflammation                         |                      3                                            1      |             
      Alveolar Epithelium, Hyperplasia     | 2                          2     1                    1              2   |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Foreign Body                         |                                                                          |             
      Hemorrhage                           |                                                                          |             
      Inflammation                         | 2                                                  1                     |             
      Goblet Cell, Hyperplasia             |                                                                          |             
      Nasolacrimal Duct, Inflammation      |                      4        2                                          |             
      Respiratory Epithelium, Hyperplasia  | 2                                                                        |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  17                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 7| 7| 6| 7| 6| 7| 7| 7| 7| 3| 6| 7| 4| 7| 6| 7| 7| 7| 1| 6| 7| 7| 7|             
                             DAY ON TEST   | 3| 3| 3| 3| 5| 2| 4| 3| 3| 3| 3| 7| 4| 3| 7| 3| 7| 3| 3| 3| 7| 2| 3| 3| 3|             
                                           | 3| 4| 3| 5| 9| 0| 8| 4| 4| 4| 5| 8| 5| 4| 7| 4| 2| 3| 3| 3| 6| 4| 3| 5| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    37.5 PPM                               | 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9| 9| 9| 9|             
                                           | 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3|             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM - cont                 |                                                                          |             
                                           |                                                                          |             
      Inflammation                         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Eye                                     |             +                                                            |             
      Hemorrhage                           |             2                                                            |             
      Lens, Cataract                       |             3                                                            |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
      Congestion                           |                                           2                              |             
      Hypoplasia                           |             3                                                            |             
      Mineralization                       |                         1        1  1     1                              |             
      Nephropathy, Chronic                 | 2  1        2  2  1  1  1  2  2        2     1     1     1     2  1  1  2|             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +|             
      Infiltration Cellular, Lymphocyte    |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  18                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 8| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 2| 3| 3| 3| 3| 3| 3| 3| 5| 5| 5| 5|             
                                           | 6| 3| 3| 4| 4| 5| 3| 5| 5| 4| 3| 3| 4| 9| 5| 4| 5| 4| 4| 3| 5| 7| 7| 7| 7|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    37.5 PPM                               | 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
                                           | 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | A  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Basophilic Focus                     |                         1                                            1  1|             
      Basophilic Focus, Multiple           |    1  2     2  1  2  1     1  3  2        1     1  2  2  1  1            |             
      Clear Cell Focus                     |                                                                          |             
      Eosinophilic Focus                   |                                  1  1        2  3                        |             
      Fatty Change                         | 2                                                                        |             
      Hepatodiaphragmatic Nodule           |          2                                   2                           |             
      Infiltration Cellular, Lymphocyte    |                                                                          |             
      Inflammation                         |                                                    2                     |             
      Necrosis                             |                                                    2                     |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    |                                                                          |             
      Acinar Cell, Atrophy                 | 1  1     2  2  1        1  2        1  2  4  1           2           1   |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Tongue                                  |                                  +                                       |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       |    1        1     2  2  1  1                    1     1     1  1  1  1  1|             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |          2     2                                                         |             
      Cytoplasmic Alteration               |                         1                                                |             
      Degeneration                         |                            2                                             |             
      Hemorrhage                           |                   1                                                      |             
      Hyperplasia                          |             2  2                                                         |             
      Hypertrophy                          |                            1                                             |             
      Vacuolization Cytoplasmic            |          2  3  2  3                    3  2        1     1               |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                1                                   1        2            |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  19                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 8| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 2| 3| 3| 3| 3| 3| 3| 3| 5| 5| 5| 5|             
                                           | 6| 3| 3| 4| 4| 5| 3| 5| 5| 4| 3| 3| 4| 9| 5| 4| 5| 4| 4| 3| 5| 7| 7| 7| 7|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    37.5 PPM                               | 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
                                           | 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8|             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM - cont                   |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  M  +  +  +  +  M  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Pars Distalis, Angiectasis           |    2     1                                2        2                     |             
      Pars Distalis, Cyst                  |    3  2  3              2           3              2  2  2           1  2|             
      Pars Distalis, Hyperplasia           |    3  1     2        2  2     2     2  3           2           3        2|             
      Pars Nervosa, Developmental          |                                                                          |             
          Malformation                     |                                                                          |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  |                               1                 2        1               |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Tissue NOS                              |                                                                          |             
      Developmental Malformation           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Clitoral Gland                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                                                          |             
      Ectasia                              |       2  3           2  1  3  3  2  2        2  2  1           2  3  3   |             
      Hyperplasia                          |                                                       2     3            |             
      Inflammation                         |    2                                                                     |             
                                            __________________________________________________________________________|             
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 | 2     3                       2                    2                 2   |             
      Bilateral, Cyst                      |                                                          2               |             
                                            __________________________________________________________________________|             
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                                          |             
      Dilatation                           |                                                       2                  |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                        2  4                              |             
      Myelofibrosis                        |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node                              |                                                                          |             
      Axillary, Hyperplasia, Lymphoid      |                                                                          |             
      Axillary, Hyperplasia, Plasma Cell   |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Bronchial                   | M  +  M  M  M  +  +  +  +  +  +  +  +  +  M  M  +  +  M  +  +  +  +  +  +|             
      Hemorrhage                           |                2  1  2  2     2     2              3     2     2  1  2   |             
      Pigmentation                         |                1  2  2  1     1  1                                       |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |             2                                                            |             
      Hemorrhage                           |                   1                                                      |             
      Hyperplasia, Lymphoid                |                                                                          |             
      Hyperplasia, Plasma Cell             |    2           2                 3                                       |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                        1                             1   |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  20                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 8| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 2| 3| 3| 3| 3| 3| 3| 3| 5| 5| 5| 5|             
                                           | 6| 3| 3| 4| 4| 5| 3| 5| 5| 4| 3| 3| 4| 9| 5| 4| 5| 4| 4| 3| 5| 7| 7| 7| 7|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    37.5 PPM                               | 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
                                           | 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mediastinal                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |    1  2  3  2  2     2  3  2        3     2  3  1  3     2  1  1  1  1  2|             
      Pigmentation                         |    2  2  3  1  1  1  2  3  1  1  1  2  1        2  2        1            |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hematopoietic Cell Proliferation     |       1                 1              2  1  1              1            |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |       1  1     1        2        1     2  1              2           2   |             
      Hemorrhage                           |                            1                                             |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                  2                                       |             
      Hemorrhage                           |                                                                          |             
      Lactation                            |    2           3                 2     2  3                              |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Ulcer                                |                                                                          |             
      Ulcer, Multiple                      |                                           4                              |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Femur, Hyperostosis                  |    2  4                                                                  |             
      Turbinate, Hyperostosis              |       2                                                                  |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Compression                          | 2                 2        2     1                          1            |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Hemorrhage                           |             2              1        1           1                        |             
      Infiltration Cellular, Histiocyte    |                                                                          |             
      Inflammation                         |                      1           1                                       |             
      Alveolar Epithelium, Hyperplasia     |                2        1           1        2  2                 1  2   |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                2                                                         |             
      Foreign Body                         |                2                                                         |             
      Hemorrhage                           |    2                                                                     |             
      Inflammation                         |                2                 2                                      1|             
      Goblet Cell, Hyperplasia             |                                                                   1     2|             
      Nasolacrimal Duct, Inflammation      |                                                                          |             
      Respiratory Epithelium, Hyperplasia  |    2                                                                     |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  21                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 8| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 2| 3| 3| 3| 3| 3| 3| 3| 5| 5| 5| 5|             
                                           | 6| 3| 3| 4| 4| 5| 3| 5| 5| 4| 3| 3| 4| 9| 5| 4| 5| 4| 4| 3| 5| 7| 7| 7| 7|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    37.5 PPM                               | 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
                                           | 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8|             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM - cont                 |                                                                          |             
                                           |                                                                          |             
      Inflammation                         |                                                          2               |             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Eye                                     |                                                                          |             
      Hemorrhage                           |                                                                          |             
      Lens, Cataract                       |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Hypoplasia                           |                                                                          |             
      Mineralization                       | 1                                   1                          1  1  2  1|             
      Nephropathy, Chronic                 | 2  1  2  1  1  1  2  1  1  2  2  2        1  1  2  1     3  2  1  1  1  1|             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  22                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 7| 7| 7| 7| 7| 7|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2|                                                        |      A     |
    37.5 PPM                               | 1| 2| 2| 2| 2| 2|                                                        |      L     |
                                           | 9| 0| 1| 2| 3| 4|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM                         |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Esophagus                               | +  +  +  +  +  +                                                         |  55        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  +                                                         |  54        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +                                                         |  55        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  +  +  +                                                         |  54        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  +  +                                                         |  53        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  +  +  +                                                         |  51        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  +  +  +  +                                                         |  51        |
                                            __________________________________________________________________________|____________|
   Liver                                   | +  M  +  +  +  +                                                         |  54        |
      Angiectasis                          |                                                                          |      1  2.0|
      Basophilic Focus                     |          1                                                               |      6  1.0|
      Basophilic Focus, Multiple           | 1           1                                                            |     34  1.8|
      Clear Cell Focus                     |                                                                          |      1  1.0|
      Eosinophilic Focus                   |                                                                          |      8  1.8|
      Fatty Change                         |       2                                                                  |      4  1.8|
      Hepatodiaphragmatic Nodule           |                                                                          |      3  2.0|
      Infiltration Cellular, Lymphocyte    |          1                                                               |      1  1.0|
      Inflammation                         |                                                                          |      3  1.3|
      Necrosis                             |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +                                                         |  55        |
      Infiltration Cellular, Lymphocyte    |       1                                                                  |      1  1.0|
      Acinar Cell, Atrophy                 | 2  1  1                                                                  |     28  1.7|
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +                                                         |  55        |
      Inflammation                         |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +                                                         |  55        |
      Inflammation                         |                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +                                                         |  54        |
                                            __________________________________________________________________________|____________|
   Tongue                                  |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +                                                         |  55        |
      Cardiomyopathy                       | 1  1  1  1  1  1                                                         |     30  1.2|
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +                                                         |  55        |
      Angiectasis                          |                                                                          |      7  1.7|
      Cytoplasmic Alteration               |                                                                          |      1  1.0|
      Degeneration                         |       1                                                                  |      2  1.5|
      Hemorrhage                           |                                                                          |      1  1.0|
      Hyperplasia                          | 1                                                                        |      5  1.8|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  23                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 7| 7| 7| 7| 7| 7|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2|                                                        |      A     |
    37.5 PPM                               | 1| 2| 2| 2| 2| 2|                                                        |      L     |
                                           | 9| 0| 1| 2| 3| 4|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 ENDOCRINE SYSTEM - cont                   |                                                                          |            |
                                           |                                                                          |            |
      Hypertrophy                          |                                                                          |      1  1.0|
      Vacuolization Cytoplasmic            |                                                                          |     13  2.1|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +                                                         |  55        |
      Hyperplasia                          |                                                                          |      4  1.3|
                                            __________________________________________________________________________|____________|
   Islets, Pancreatic                      |                                                                          |   1        |
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | +  +  +  +  +  +                                                         |  50        |
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +                                                         |  53        |
      Pars Distalis, Angiectasis           |    2  3                                                                  |     12  2.3|
      Pars Distalis, Cyst                  |          3  1                                                            |     21  2.1|
      Pars Distalis, Hyperplasia           | 2  3  3        1                                                         |     24  2.2|
      Pars Nervosa, Developmental          |                                                                          |            |
          Malformation                     |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +                                                         |  55        |
      C-Cell, Hyperplasia                  |                                                                          |      4  1.8|
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Tissue NOS                              |                                                                          |   1        |
      Developmental Malformation           |                                                                          |      1     |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Clitoral Gland                          | +  +  +  +  +  +                                                         |  54        |
      Abscess                              |                                                                          |      1  3.0|
      Ectasia                              | 2  2  2  2  2  3                                                         |     33  2.2|
      Hyperplasia                          |                                                                          |      4  2.5|
      Inflammation                         |          1                                                               |      3  2.0|
                                            __________________________________________________________________________|____________|
   Ovary                                   | +  +  +  +  +  +                                                         |  55        |
      Cyst                                 |    2     2                                                               |      9  2.1|
      Bilateral, Cyst                      |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Uterus                                  | +  +  +  +  +  +                                                         |  55        |
      Cyst                                 |                                                                          |      1  2.0|
      Dilatation                           |                                                                          |      2  2.0|
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +                                                         |  55        |
      Hyperplasia                          |                                                                          |      7  2.4|
      Myelofibrosis                        |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Lymph Node                              |                                                                          |   1        |
      Axillary, Hyperplasia, Lymphoid      |                                                                          |      1  3.0|
      Axillary, Hyperplasia, Plasma Cell   |                                                                          |      1  2.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  24                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 7| 7| 7| 7| 7| 7|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2|                                                        |      A     |
    37.5 PPM                               | 1| 2| 2| 2| 2| 2|                                                        |      L     |
                                           | 9| 0| 1| 2| 3| 4|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Lymph Node, Bronchial                   | +  +  +  +  +  +                                                         |  40        |
      Hemorrhage                           | 1  2  1  2  2  1                                                         |     23  1.7|
      Pigmentation                         |                                                                          |      7  1.4|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +                                                         |  55        |
      Cyst                                 |                                                                          |      1  2.0|
      Hemorrhage                           |                                                                          |      1  1.0|
      Hyperplasia, Lymphoid                |                                                                          |      1  2.0|
      Hyperplasia, Plasma Cell             |                                                                          |      3  2.3|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +                                                         |  55        |
      Hemorrhage                           |       1                                                                  |      8  1.1|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mediastinal                 | +  +  +  +  +  +                                                         |  54        |
      Hemorrhage                           | 2  2  2  2  2  1                                                         |     41  1.9|
      Pigmentation                         |                                                                          |     31  1.7|
                                            __________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +                                                         |  55        |
      Hematopoietic Cell Proliferation     |                                                                          |     11  1.6|
                                            __________________________________________________________________________|____________|
   Thymus                                  | +  +  +  +  +  +                                                         |  53        |
      Atrophy                              |    2  1  1     1                                                         |     26  1.5|
      Hemorrhage                           |                                                                          |      2  1.5|
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Mammary Gland                           | +  +  +  +  +  +                                                         |  55        |
      Abscess                              |                                                                          |      1  2.0|
      Hemorrhage                           |                                                                          |      1  2.0|
      Lactation                            |                                                                          |      7  2.3|
                                            __________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +                                                         |  55        |
      Ulcer                                |          2                                                               |      1  2.0|
      Ulcer, Multiple                      |                                                                          |      1  4.0|
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +                                                         |  55        |
      Femur, Hyperostosis                  |                                                                          |      6  3.0|
      Turbinate, Hyperostosis              |                                                                          |      3  2.3|
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +                                                         |  55        |
      Compression                          |                                                                          |      8  1.9|
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Larynx                                  | +  +  +  +  +  +                                                         |  55        |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  25                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 7| 7| 7| 7| 7| 7|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2|                                                        |      A     |
    37.5 PPM                               | 1| 2| 2| 2| 2| 2|                                                        |      L     |
                                           | 9| 0| 1| 2| 3| 4|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 RESPIRATORY SYSTEM - cont                 |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +                                                         |  55        |
      Congestion                           |                                                                          |      4  2.5|
      Hemorrhage                           | 1        2  1                                                            |     15  1.3|
      Infiltration Cellular, Histiocyte    |                                                                          |      1  1.0|
      Inflammation                         |                                                                          |      4  1.5|
      Alveolar Epithelium, Hyperplasia     |                                                                          |     12  1.6|
                                            __________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +                                                         |  55        |
      Angiectasis                          |                                                                          |      1  2.0|
      Foreign Body                         |                                                                          |      1  2.0|
      Hemorrhage                           |                                                                          |      1  2.0|
      Inflammation                         |                                                                          |      5  1.6|
      Goblet Cell, Hyperplasia             | 1        1                                                               |      4  1.3|
      Nasolacrimal Duct, Inflammation      |                                                                          |      2  3.0|
      Respiratory Epithelium, Hyperplasia  |                                                                          |      2  2.0|
                                            __________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +                                                         |  55        |
      Inflammation                         |                                                                          |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Eye                                     |                                                                          |   1        |
      Hemorrhage                           |                                                                          |      1  2.0|
      Lens, Cataract                       |                                                                          |      1  3.0|
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +                                                         |  55        |
      Congestion                           |                                                                          |      1  2.0|
      Hypoplasia                           |                                                                          |      1  3.0|
      Mineralization                       | 1  1  1  1  2  1                                                         |     16  1.1|
      Nephropathy, Chronic                 | 1  1  1     1  1                                                         |     44  1.4|
                                            __________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  +  +  +                                                         |  54        |
      Infiltration Cellular, Lymphocyte    |          1                                                               |      1  1.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  26                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 6| 7| 3| 7| 6| 7| 7| 7| 6| 7| 7| 7| 7| 7| 7| 6| 7| 7| 5| 3| 7| 7| 7| 7|             
                             DAY ON TEST   | 3| 5| 3| 1| 2| 0| 3| 3| 3| 7| 3| 3| 3| 3| 3| 3| 4| 3| 3| 0| 7| 3| 3| 3| 0|             
                                           | 5| 3| 3| 6| 6| 4| 4| 4| 5| 4| 4| 0| 4| 5| 3| 4| 7| 5| 3| 4| 7| 3| 3| 4| 8|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3|             
    75 PPM                                 | 8| 8| 8| 8| 8| 8| 8| 8| 8| 9| 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  A  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  A  A  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  A  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  A  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  +  A  A  +  +  +  +  +  +  A  A  +  +  +  +|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                2  2                                                      |             
      Basophilic Focus                     | 1              2        1  1        1           1                        |             
      Basophilic Focus, Multiple           |    2  3     2     2  1        1        2  1  2        1        1  2  1  1|             
      Clear Cell Focus                     |                                                                          |             
      Clear Cell Focus, Multiple           |                                                                          |             
      Congestion                           |                                  2                       2  2            |             
      Eosinophilic Focus                   |                3                                                         |             
      Eosinophilic Focus, Multiple         |             3                                                     2  3   |             
      Fatty Change                         |                               2  1           1                    2  3   |             
      Hepatodiaphragmatic Nodule           |    X                 2              2                                    |             
      Infiltration Cellular, Lymphocyte    |                                                       1                  |             
      Inflammation                         |                2              2                    1  1                  |             
      Mixed Cell Focus                     |                                           1                    2         |             
      Necrosis                             |                                     2                                    |             
      Pigmentation                         |                                                                          |             
      Vacuolization Cytoplasmic            | 3                       3              3           3                     |             
      Centrilobular, Cytoplasmic Alteration|                   2                                                      |             
                                            __________________________________________________________________________|             
   Mesentery                               |                                                                          |             
      Fat, Necrosis                        |                                                                          |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Accessory Spleen                     |                                                                          |             
      Acinar Cell, Atrophy                 | 1                    2  1     1           3  1  1  2           1  3  2   |             
                                            __________________________________________________________________________|             
   Pharynx                                 |       +           +                                                      |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                2                                                         |             
      Inflammation                         |                3                                                         |             
      Ulcer                                |                         2                                                |             
      Ulcer, Multiple                      |                4                                                         |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation                         |                2                                                         |             
                                            __________________________________________________________________________|             
   Tongue                                  |                                                       +                  |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       | 1  1  1     1  1  1  1        2  2        1  1  1     1                 2|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  27                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 6| 7| 3| 7| 6| 7| 7| 7| 6| 7| 7| 7| 7| 7| 7| 6| 7| 7| 5| 3| 7| 7| 7| 7|             
                             DAY ON TEST   | 3| 5| 3| 1| 2| 0| 3| 3| 3| 7| 3| 3| 3| 3| 3| 3| 4| 3| 3| 0| 7| 3| 3| 3| 0|             
                                           | 5| 3| 3| 6| 6| 4| 4| 4| 5| 4| 4| 0| 4| 5| 3| 4| 7| 5| 3| 4| 7| 3| 3| 4| 8|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3|             
    75 PPM                                 | 8| 8| 8| 8| 8| 8| 8| 8| 8| 9| 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM - cont              |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |       1           3              2                                       |             
      Congestion                           |                                     2                                    |             
      Degeneration                         |    2                                                                     |             
      Hemorrhage                           |                                                                          |             
      Hypertrophy                          |                                                                          |             
      Vacuolization Cytoplasmic            |                                           2  3                 2         |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                  2                                       |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  M  +  +  M  +  +  M  +  +  +  +  +  +  +  M  +  M  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |    2                                                                     |             
      Pars Distalis, Angiectasis           |                               3     4     3                    2         |             
      Pars Distalis, Cyst                  |       1           2           3                    1           2  2      |             
      Pars Distalis, Hyperplasia           |             1     2                                2              3  3  2|             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  | 1     2                                         1                        |             
      Follicle, Dilatation                 |                                                                   2      |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Clitoral Gland                          | +  M  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                                                          |             
      Ectasia                              |       2        3  2  2  2        3  3  2  2  2     2     3  2     1  2  3|             
      Hyperplasia                          |                                                                   2      |             
      Inflammation                         |                   3                                                      |             
                                            __________________________________________________________________________|             
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                                      2   |             
      Hemorrhage                           |                                        1                                 |             
      Bilateral, Cyst                      |                                                                          |             
                                            __________________________________________________________________________|             
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Dilatation                           |       1                                2                                 |             
      Prolapse                             |          3                                                               |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                2                                                         |             
      Hyperplasia                          |    3     1  3                                                            |             
      Myelofibrosis                        |                1                                                         |             
                                            __________________________________________________________________________|             
   Lymph Node, Bronchial                   | +  +  +  +  M  M  +  +  +  M  +  +  +  +  +  +  M  +  M  M  M  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  28                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 6| 7| 3| 7| 6| 7| 7| 7| 6| 7| 7| 7| 7| 7| 7| 6| 7| 7| 5| 3| 7| 7| 7| 7|             
                             DAY ON TEST   | 3| 5| 3| 1| 2| 0| 3| 3| 3| 7| 3| 3| 3| 3| 3| 3| 4| 3| 3| 0| 7| 3| 3| 3| 0|             
                                           | 5| 3| 3| 6| 6| 4| 4| 4| 5| 4| 4| 0| 4| 5| 3| 4| 7| 5| 3| 4| 7| 3| 3| 4| 8|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3|             
    75 PPM                                 | 8| 8| 8| 8| 8| 8| 8| 8| 8| 9| 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Hemorrhage                           |                      3        1              2     3              1  2   |             
      Pigmentation                         |    1  1           1  2           2           2                           |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                                                          |             
      Hyperplasia, Lymphoid                |                                                                          |             
      Pigmentation                         |                                                                   1      |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |    3        3     2                                      2               |             
                                            __________________________________________________________________________|             
   Lymph Node, Mediastinal                 | +  +  +  +  +  +  +  +  +  M  +  +  M  +  +  +  +  +  M  +  +  +  +  M  +|             
      Hemorrhage                           | 3  2  1     2     1  1  2        2     2  2  1  3  2              1      |             
      Pigmentation                         | 2           2     2  2  1        2     1  1  2  2  2           1  1      |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +|             
      Hematopoietic Cell Proliferation     |    2     3  2                                                     1      |             
      Pigmentation                         |                2                             3                           |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +|             
      Atrophy                              | 1  1  1     1  2  3     1  2  1        1  2     3  2     2     2  4     3|             
      Congestion                           |                                                          3               |             
      Hemorrhage                           |       1                             3                       1            |             
      Necrosis                             |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Lactation                            |                3           2  2                 2              2     2   |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Femur, Hyperostosis                  |                                     3                 2                  |             
      Turbinate, Hyperostosis              |                                     3  3                                 |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Compression                          |                2        2  3  2     2  2     2  2                        |             
      Hemorrhage                           |                3                 2           1                           |             
      Hydrocephalus                        |                3                                                         |             
      Necrosis                             |                2                 3              3                        |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                                                          |             
      Inflammation                         |                2                                1     2                  |             
      Epithelium, Hyperplasia              |                                  2                                       |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                  2              2        2  2           2|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  29                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 6| 7| 3| 7| 6| 7| 7| 7| 6| 7| 7| 7| 7| 7| 7| 6| 7| 7| 5| 3| 7| 7| 7| 7|             
                             DAY ON TEST   | 3| 5| 3| 1| 2| 0| 3| 3| 3| 7| 3| 3| 3| 3| 3| 3| 4| 3| 3| 0| 7| 3| 3| 3| 0|             
                                           | 5| 3| 3| 6| 6| 4| 4| 4| 5| 4| 4| 0| 4| 5| 3| 4| 7| 5| 3| 4| 7| 3| 3| 4| 8|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3|             
    75 PPM                                 | 8| 8| 8| 8| 8| 8| 8| 8| 8| 9| 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM - cont                 |                                                                          |             
                                           |                                                                          |             
      Hemorrhage                           |                                  2              1           1           2|             
      Infiltration Cellular, Histiocyte    |                                                                      1   |             
      Inflammation                         |    2                                                                     |             
      Alveolar Epithelium, Hyperplasia     |                   1                 1  2  2  1        1              1   |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                  2                                       |             
      Inflammation                         |             2                                                            |             
      Goblet Cell, Hyperplasia             |                                                                          |             
      Olfactory Epithelium, Cytoplasmic    |                                                                          |             
          Alteration                       |                                                                          |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Eye                                     |                                  +                                       |             
      Bilateral, Lens, Cataract            |                                  3                                       |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                2                                                         |             
      Congestion                           |                                                          2               |             
      Mineralization                       |          1     1              1                          1  1            |             
      Necrosis                             |                                                                   1      |             
      Nephropathy, Chronic                 | 2     1     1           2  2  2  3     2  1  1  1  1  1        2     1   |             
      Pigmentation                         |                   1                       1                              |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Dilatation                           |                                                          3               |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  30                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 6| 7| 7| 7| 7| 7| 6| 6| 7| 7| 7| 7| 7| 7| 6| 7| 7| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 3| 3| 3| 3| 3| 3| 3| 3| 1| 5| 0| 3| 3| 3| 3| 3| 8| 3| 3| 3| 3| 5| 5| 5| 5|             
                                           | 3| 4| 6| 3| 4| 5| 5| 5| 0| 0| 5| 5| 4| 4| 4| 3| 6| 3| 3| 4| 4| 7| 7| 7| 7|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    75 PPM                                 | 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  A  +  +  +  +  +  +  +  A  +  +  +  +  +  A  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  A  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Basophilic Focus                     |       2                 1                                         1      |             
      Basophilic Focus, Multiple           | 2           1  1  2  3        1  1  1  2  2  2  1     2  2  1  1         |             
      Clear Cell Focus                     |             1                                1                           |             
      Clear Cell Focus, Multiple           |                                           1                              |             
      Congestion                           |                                                                          |             
      Eosinophilic Focus                   | 2                    2           1                                       |             
      Eosinophilic Focus, Multiple         |                                                                          |             
      Fatty Change                         |          1     1           2                                1            |             
      Hepatodiaphragmatic Nodule           | 2                                                     X                  |             
      Infiltration Cellular, Lymphocyte    |                                                                          |             
      Inflammation                         |                                  1                 1                     |             
      Mixed Cell Focus                     |                                                                          |             
      Necrosis                             |                                                                          |             
      Pigmentation                         |                                                                         1|             
      Vacuolization Cytoplasmic            |                                                                          |             
      Centrilobular, Cytoplasmic Alteration|                                                                          |             
                                            __________________________________________________________________________|             
   Mesentery                               |          +     +                                                         |             
      Fat, Necrosis                        |          3     3                                                         |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Accessory Spleen                     |                                                             X            |             
      Acinar Cell, Atrophy                 |       1  1     3  1  1     1  1              1        2  1        1  1   |             
                                            __________________________________________________________________________|             
   Pharynx                                 |                                                                          |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                            3                                             |             
      Inflammation                         |                                                                          |             
      Ulcer                                |                            3                                             |             
      Ulcer, Multiple                      |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Tongue                                  |                                                       +                  |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       | 1  2  2     1     1        1  1        1  2           1     2  1  1  1  1|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  31                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 6| 7| 7| 7| 7| 7| 6| 6| 7| 7| 7| 7| 7| 7| 6| 7| 7| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 3| 3| 3| 3| 3| 3| 3| 3| 1| 5| 0| 3| 3| 3| 3| 3| 8| 3| 3| 3| 3| 5| 5| 5| 5|             
                                           | 3| 4| 6| 3| 4| 5| 5| 5| 0| 0| 5| 5| 4| 4| 4| 3| 6| 3| 3| 4| 4| 7| 7| 7| 7|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    75 PPM                                 | 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM - cont              |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |    2                             2     2  3  2     2        2            |             
      Congestion                           |                                                                          |             
      Degeneration                         |                                                                          |             
      Hemorrhage                           |                                                    1                     |             
      Hypertrophy                          |    2                                                                     |             
      Vacuolization Cytoplasmic            |    1                                      1              1               |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                            1           1                                 |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  +  M  M  +  M  +  +  +  +  M  +  +  +  +  +  +  M  +  +  +  +|             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                                          |             
      Pars Distalis, Angiectasis           |    3                                                                     |             
      Pars Distalis, Cyst                  |          2        2              3     2           2                     |             
      Pars Distalis, Hyperplasia           |                   2              2  2     2  3     2     2              1|             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  |                                           1                              |             
      Follicle, Dilatation                 |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Clitoral Gland                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                        3                                 |             
      Ectasia                              | 3  2  3     2     2  1  2  2  1     2        2  2     2  1     2     2  2|             
      Hyperplasia                          |                                                                          |             
      Inflammation                         |                3        2                             1                 1|             
                                            __________________________________________________________________________|             
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                             2            |             
      Hemorrhage                           |                                                                          |             
      Bilateral, Cyst                      |                                                                2         |             
                                            __________________________________________________________________________|             
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Dilatation                           |                      3                                            2      |             
      Prolapse                             |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                            3                                             |             
      Hyperplasia                          |                3                                   3     2               |             
      Myelofibrosis                        |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Bronchial                   | +  +  M  +  +  +  +  +  +  M  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  32                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 6| 7| 7| 7| 7| 7| 6| 6| 7| 7| 7| 7| 7| 7| 6| 7| 7| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 3| 3| 3| 3| 3| 3| 3| 3| 1| 5| 0| 3| 3| 3| 3| 3| 8| 3| 3| 3| 3| 5| 5| 5| 5|             
                                           | 3| 4| 6| 3| 4| 5| 5| 5| 0| 0| 5| 5| 4| 4| 4| 3| 6| 3| 3| 4| 4| 7| 7| 7| 7|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    75 PPM                                 | 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Hemorrhage                           | 1        2  1                       1  2  4                 1  1     1  2|             
      Pigmentation                         |             1                       1  2                                 |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  M  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                                 2        2               |             
      Hyperplasia, Lymphoid                |                                                       2                  |             
      Pigmentation                         |                                                    1                     |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |             2        1  2           2                                    |             
                                            __________________________________________________________________________|             
   Lymph Node, Mediastinal                 | +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           | 2  1     3  1  1  2  2     1  2  2  2  2  2  2     1     1  3  1  2  1  2|             
      Pigmentation                         | 2  1     2  1     2  2     2  1  2  2  2  2  2  2  2  2  1  3            |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hematopoietic Cell Proliferation     |             1                                      1                    2|             
      Pigmentation                         |                            2                                             |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |          2  1     1  3  1  3  3  2     2  1  1  3     2           1     1|             
      Congestion                           |                                                                          |             
      Hemorrhage                           |                                                       1                  |             
      Necrosis                             |       4                                                                  |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Lactation                            |                         2  2                          1                  |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Femur, Hyperostosis                  |                                                                          |             
      Turbinate, Hyperostosis              |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Compression                          |    2           2        3     2                 2     1     2            |             
      Hemorrhage                           |          1                 3                                             |             
      Hydrocephalus                        |                                                                          |             
      Necrosis                             |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                              2                           |             
      Inflammation                         |                                                       2                  |             
      Epithelium, Hyperplasia              |                                                       2                  |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |       2                                                                  |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  33                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 6| 7| 7| 7| 7| 7| 6| 6| 7| 7| 7| 7| 7| 7| 6| 7| 7| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 3| 3| 3| 3| 3| 3| 3| 3| 1| 5| 0| 3| 3| 3| 3| 3| 8| 3| 3| 3| 3| 5| 5| 5| 5|             
                                           | 3| 4| 6| 3| 4| 5| 5| 5| 0| 0| 5| 5| 4| 4| 4| 3| 6| 3| 3| 4| 4| 7| 7| 7| 7|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    75 PPM                                 | 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM - cont                 |                                                                          |             
                                           |                                                                          |             
      Hemorrhage                           |             1              1        2                       1  1         |             
      Infiltration Cellular, Histiocyte    |                                                                          |             
      Inflammation                         | 2                          1                                             |             
      Alveolar Epithelium, Hyperplasia     |                            2     2  2        2                           |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                     2           2                        |             
      Inflammation                         |    1                                         2  2                        |             
      Goblet Cell, Hyperplasia             |                                                 1                        |             
      Olfactory Epithelium, Cytoplasmic    |                                                                          |             
          Alteration                       |                                                                      2   |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Eye                                     |                                                                          |             
      Bilateral, Lens, Cataract            |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Congestion                           |                                                                          |             
      Mineralization                       |       1                                                        1  1  1   |             
      Necrosis                             |                                                                          |             
      Nephropathy, Chronic                 | 1  2     1  2  2  1  1  2  2  2  1  2  1  1  1  1     1  1  2     1  1  1|             
      Pigmentation                         |                                           1        1                     |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Dilatation                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  34                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 7| 7| 7| 7| 7| 7|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3|                                                        |      A     |
    75 PPM                                 | 3| 3| 3| 3| 3| 3|                                                        |      L     |
                                           | 1| 2| 3| 4| 5| 6|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM                         |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Esophagus                               | +  +  +  +  +  +                                                         |  56        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  +                                                         |  54        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +                                                         |  56        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  +  +  +                                                         |  53        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  +  +                                                         |  53        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  +  +  +                                                         |  51        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  +  +  +  +                                                         |  50        |
                                            __________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +                                                         |  56        |
      Angiectasis                          |                                                                          |      2  2.0|
      Basophilic Focus                     | 1  1  1  1  1  1                                                         |     15  1.1|
      Basophilic Focus, Multiple           |                                                                          |     30  1.6|
      Clear Cell Focus                     |                                                                          |      2  1.0|
      Clear Cell Focus, Multiple           |                                                                          |      1  1.0|
      Congestion                           |                                                                          |      3  2.0|
      Eosinophilic Focus                   |       2                                                                  |      5  2.0|
      Eosinophilic Focus, Multiple         |                                                                          |      3  2.7|
      Fatty Change                         |                                                                          |      9  1.6|
      Hepatodiaphragmatic Nodule           |                                                                          |      5  2.0|
      Infiltration Cellular, Lymphocyte    |                                                                          |      1  1.0|
      Inflammation                         |                                                                          |      6  1.3|
      Mixed Cell Focus                     |                                                                          |      2  1.5|
      Necrosis                             |                                                                          |      1  2.0|
      Pigmentation                         |                                                                          |      1  1.0|
      Vacuolization Cytoplasmic            |                                                                          |      4  3.0|
      Centrilobular, Cytoplasmic Alteration|                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Mesentery                               | +              +                                                         |   4        |
      Fat, Necrosis                        | 3              3                                                         |      4  3.0|
                                            __________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +                                                         |  56        |
      Accessory Spleen                     |                                                                          |      1     |
      Acinar Cell, Atrophy                 |    2     2     1                                                         |     26  1.5|
                                            __________________________________________________________________________|____________|
   Pharynx                                 |                                                                          |   2        |
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +                                                         |  55        |
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +                                                         |  56        |
      Hyperplasia                          |             2                                                            |      3  2.3|
      Inflammation                         |                                                                          |      1  3.0|
      Ulcer                                |                                                                          |      2  2.5|
      Ulcer, Multiple                      |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +                                                         |  55        |
      Inflammation                         |                                                                          |      1  2.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  35                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 7| 7| 7| 7| 7| 7|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3|                                                        |      A     |
    75 PPM                                 | 3| 3| 3| 3| 3| 3|                                                        |      L     |
                                           | 1| 2| 3| 4| 5| 6|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM - cont                  |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Tongue                                  |                                                                          |   2        |
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +                                                         |  56        |
      Cardiomyopathy                       | 1  1     1  1  1                                                         |     34  1.2|
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +                                                         |  56        |
      Angiectasis                          |                                                                          |     10  2.1|
      Congestion                           |                                                                          |      1  2.0|
      Degeneration                         |                                                                          |      1  2.0|
      Hemorrhage                           |                                                                          |      1  1.0|
      Hypertrophy                          |                                                                          |      1  2.0|
      Vacuolization Cytoplasmic            |                                                                          |      6  1.7|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +                                                         |  55        |
      Hyperplasia                          |                                                                          |      3  1.3|
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | +  +  +  +  +  +                                                         |  46        |
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +                                                         |  55        |
      Cyst                                 |                                                                          |      1  2.0|
      Pars Distalis, Angiectasis           |                                                                          |      5  3.0|
      Pars Distalis, Cyst                  |       3     1                                                            |     13  2.0|
      Pars Distalis, Hyperplasia           |                1                                                         |     15  2.0|
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +                                                         |  56        |
      C-Cell, Hyperplasia                  |             2                                                            |      5  1.4|
      Follicle, Dilatation                 |                                                                          |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Clitoral Gland                          | +  +  +  +  +  +                                                         |  54        |
      Abscess                              |                                                                          |      1  3.0|
      Ectasia                              | 3  3  1  2  3                                                            |     38  2.1|
      Hyperplasia                          |                                                                          |      1  2.0|
      Inflammation                         |                                                                          |      5  2.0|
                                            __________________________________________________________________________|____________|
   Ovary                                   | +  +  +  +  +  +                                                         |  56        |
      Cyst                                 |                                                                          |      2  2.0|
      Hemorrhage                           |                                                                          |      1  1.0|
      Bilateral, Cyst                      |                                                                          |      1  2.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  36                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 7| 7| 7| 7| 7| 7|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3|                                                        |      A     |
    75 PPM                                 | 3| 3| 3| 3| 3| 3|                                                        |      L     |
                                           | 1| 2| 3| 4| 5| 6|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 GENITAL SYSTEM - cont                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Uterus                                  | +  +  +  +  +  +                                                         |  56        |
      Dilatation                           | 2                                                                        |      5  2.0|
      Prolapse                             |                                                                          |      1  3.0|
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +                                                         |  56        |
      Atrophy                              |                                                                          |      2  2.5|
      Hyperplasia                          |                                                                          |      6  2.5|
      Myelofibrosis                        |                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Bronchial                   | +  +  +  +  +  +                                                         |  46        |
      Hemorrhage                           | 1  1  2  2  1  1                                                         |     22  1.6|
      Pigmentation                         |                                                                          |      9  1.4|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +                                                         |  53        |
      Hemorrhage                           |                                                                          |      2  2.0|
      Hyperplasia, Lymphoid                |                                                                          |      1  2.0|
      Pigmentation                         |                                                                          |      2  1.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +                                                         |  56        |
      Hemorrhage                           |                                                                          |      8  2.1|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mediastinal                 | +  +  +  +  +  +                                                         |  51        |
      Hemorrhage                           | 3  2  2  2  1  1                                                         |     41  1.8|
      Pigmentation                         |                                                                          |     31  1.7|
                                            __________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +                                                         |  54        |
      Hematopoietic Cell Proliferation     |                                                                          |      7  1.7|
      Pigmentation                         |                                                                          |      3  2.3|
                                            __________________________________________________________________________|____________|
   Thymus                                  | +  +  +  +  +  +                                                         |  55        |
      Atrophy                              |    1     2                                                               |     34  1.8|
      Congestion                           |                                                                          |      1  3.0|
      Hemorrhage                           |                                                                          |      4  1.5|
      Necrosis                             |                                                                          |      1  4.0|
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Mammary Gland                           | +  +  +  +  +  +                                                         |  56        |
      Lactation                            |                                                                          |      9  2.0|
                                            __________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +                                                         |  56        |
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +                                                         |  56        |
      Femur, Hyperostosis                  |                                                                          |      2  2.5|
      Turbinate, Hyperostosis              |                                                                          |      2  3.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  37                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 7| 7| 7| 7| 7| 7|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3|                                                        |      A     |
    75 PPM                                 | 3| 3| 3| 3| 3| 3|                                                        |      L     |
                                           | 1| 2| 3| 4| 5| 6|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 MUSCULOSKELETAL SYSTEM - cont             |                                                                          |            |
                                           |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +                                                         |  56        |
      Compression                          |                                                                          |     15  2.1|
      Hemorrhage                           |                                                                          |      5  2.0|
      Hydrocephalus                        |                                                                          |      1  3.0|
      Necrosis                             |                                                                          |      3  2.7|
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Larynx                                  | +  +  +  +  +  +                                                         |  56        |
      Hemorrhage                           |                                                                          |      1  2.0|
      Inflammation                         |                                                                          |      4  1.8|
      Epithelium, Hyperplasia              |                                                                          |      2  2.0|
                                            __________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +                                                         |  56        |
      Congestion                           |                                                                          |      6  2.0|
      Hemorrhage                           |                3                                                         |     10  1.5|
      Infiltration Cellular, Histiocyte    |                                                                          |      1  1.0|
      Inflammation                         |                                                                          |      3  1.7|
      Alveolar Epithelium, Hyperplasia     |                1                                                         |     12  1.5|
                                            __________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +                                                         |  55        |
      Angiectasis                          |                                                                          |      3  2.0|
      Inflammation                         |                                                                          |      4  1.8|
      Goblet Cell, Hyperplasia             | 1                                                                        |      2  1.0|
      Olfactory Epithelium, Cytoplasmic    |                                                                          |            |
          Alteration                       |             2  2                                                         |      3  2.0|
                                            __________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +                                                         |  56        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Eye                                     |                                                                          |   1        |
      Bilateral, Lens, Cataract            |                                                                          |      1  3.0|
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +                                                         |  56        |
      Angiectasis                          |                                                                          |      1  2.0|
      Congestion                           |                                                                          |      1  2.0|
      Mineralization                       | 1  1  1  1  2  1                                                         |     15  1.1|
      Necrosis                             |                                                                          |      1  1.0|
      Nephropathy, Chronic                 | 1  1  1  1  1  1                                                         |     43  1.4|
      Pigmentation                         |                                                                          |      4  1.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  38                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 7| 7| 7| 7| 7| 7|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3|                                                        |      A     |
    75 PPM                                 | 3| 3| 3| 3| 3| 3|                                                        |      L     |
                                           | 1| 2| 3| 4| 5| 6|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 URINARY SYSTEM - cont                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  +  +  +                                                         |  55        |
      Dilatation                           |                                                                          |      1  3.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  39                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 6| 7| 7| 7| 3| 7| 7| 7| 7| 7| 2| 6| 7| 7| 7|             
                             DAY ON TEST   | 8| 3| 3| 3| 3| 3| 3| 3| 3| 3| 0| 3| 3| 3| 9| 3| 3| 3| 3| 3| 3| 7| 3| 3| 3|             
                                           | 1| 4| 5| 3| 4| 5| 3| 3| 3| 4| 8| 4| 5| 5| 4| 3| 3| 4| 5| 4| 4| 4| 5| 5| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|             
    150 PPM                                | 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1|             
                                           | 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +|             
      Abscess                              |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  A  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  A  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  A  +  +  +  +|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Basophilic Focus                     |       1  2                    1                 1                        |             
      Basophilic Focus, Multiple           | 1  1           2  3  1  2  3     2  2     1  2     3  2  2     2  2  2  2|             
      Clear Cell Focus                     |                                              1                           |             
      Clear Cell Focus, Multiple           |                      1                                                   |             
      Congestion                           | 1                                                           2            |             
      Developmental Malformation           |                                                    2                     |             
      Eosinophilic Focus                   |       2                                                  2               |             
      Eosinophilic Focus, Multiple         |                                                                          |             
      Fatty Change                         |             2                                                           1|             
      Hemorrhage                           |                                                                          |             
      Hepatodiaphragmatic Nodule           |                2           2              X     2                        |             
      Infiltration Cellular, Lymphocyte    |                                                                          |             
      Inflammation                         |                                  1                    2                  |             
      Necrosis                             |                                                    2                     |             
      Pigmentation                         |                                                       2                  |             
                                            __________________________________________________________________________|             
   Mesentery                               |                                                                         +|             
      Fat, Necrosis                        |                                                                         3|             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Ectopic Liver                        |                                                                          |             
      Acinar Cell, Atrophy                 |                1  3           1     2        1  2        2  2  2  1  1   |             
                                            __________________________________________________________________________|             
   Pharynx                                 |                                        +                                 |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                                                          |             
      Inflammation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Ulcer                                |                                                                          |             
                                            __________________________________________________________________________|             
   Tongue                                  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       |          1  1  2  2     2  1  2  2  1  2     2  2  2  2     1  2  1  2  2|             
      Atrium, Thrombosis                   |                                                    3                     |             
      Endocardium, Proliferation           | 3                                                                        |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  40                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 6| 7| 7| 7| 3| 7| 7| 7| 7| 7| 2| 6| 7| 7| 7|             
                             DAY ON TEST   | 8| 3| 3| 3| 3| 3| 3| 3| 3| 3| 0| 3| 3| 3| 9| 3| 3| 3| 3| 3| 3| 7| 3| 3| 3|             
                                           | 1| 4| 5| 3| 4| 5| 3| 3| 3| 4| 8| 4| 5| 5| 4| 3| 3| 4| 5| 4| 4| 4| 5| 5| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|             
    150 PPM                                | 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1|             
                                           | 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7|             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM - cont                   |                                                                          |             
                                           |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                2     2           2              2     3                  |             
      Congestion                           |                                                    3                     |             
      Degeneration                         |             3                                                            |             
      Hemorrhage                           |             3                       1  2                                 |             
      Hyperplasia                          |                      2                                               1   |             
      Hypertrophy                          |                                                                          |             
      Infiltration Cellular, Lymphocyte    |                                                                          |             
      Vacuolization Cytoplasmic            |       2     3        2           2              1     2                  |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |             2                                      1                     |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      |                                                    +                     |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  M  M  +  M|             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Congestion                           |                                                    2                     |             
      Pars Distalis, Angiectasis           |    2                                2                 4        3         |             
      Pars Distalis, Cyst                  |                                  2              2                        |             
      Pars Distalis, Hyperplasia           |    3        2              2  2  2  2        3  1  2     2               |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  | 2     2                                                                  |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Clitoral Gland                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Ectasia                              | 2  2  3  3           3  2  3        2  3  2     2  2  3  2     3  3      |             
      Hyperplasia                          | 3                                   2  2                       3         |             
      Inflammation                         |                                                             1  3         |             
                                            __________________________________________________________________________|             
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                                   2      |             
                                            __________________________________________________________________________|             
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                     2                                    |             
      Cyst                                 |                                     4                                    |             
      Dilatation                           |                                                    2                     |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                     2     2                    2         |             
      Myelofibrosis                        |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node                              |                                  +        +                              |             
      Axillary, Hyperplasia, Lymphoid      |                                           2                              |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  41                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 6| 7| 7| 7| 3| 7| 7| 7| 7| 7| 2| 6| 7| 7| 7|             
                             DAY ON TEST   | 8| 3| 3| 3| 3| 3| 3| 3| 3| 3| 0| 3| 3| 3| 9| 3| 3| 3| 3| 3| 3| 7| 3| 3| 3|             
                                           | 1| 4| 5| 3| 4| 5| 3| 3| 3| 4| 8| 4| 5| 5| 4| 3| 3| 4| 5| 4| 4| 4| 5| 5| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|             
    150 PPM                                | 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1|             
                                           | 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Lumbar, Pigmentation                 |                                  2                                       |             
                                            __________________________________________________________________________|             
   Lymph Node, Bronchial                   | M  +  +  +  M  +  M  +  +  +  +  M  M  M  +  M  +  +  +  +  +  M  M  M  M|             
      Hemorrhage                           |    1  1        2     2                    2     2  2        2            |             
      Pigmentation                         |       1              1                          2                        |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  M  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  M  +  +  +  +  +|             
      Hemorrhage                           |                                                                          |             
      Hyperplasia, Plasma Cell             | 2                                                                        |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                     2              3        2            |             
      Pigmentation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mediastinal                 | +  +  +  +  +  +  +  +  +  M  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |    1  2  1           1        2  1  3  2     1  1  3  2     1  3     2   |             
      Pigmentation                         |       1  1  1  1  1  2                 2        1     2                  |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Developmental Malformation           |                                                                      2   |             
      Hematopoietic Cell Proliferation     |    1                                2     2                    2         |             
      Pigmentation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +|             
      Atrophy                              |    1     3  2        2  1  1  2  2  2        2     2                     |             
      Congestion                           |                                                                          |             
      Cyst                                 |                                                          3               |             
      Hemorrhage                           |                               2                             3            |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Galactocele                          |                                                                         3|             
      Hyperplasia                          |                                                                          |             
      Inflammation                         |          3                                                               |             
      Lactation                            |                2  1                    2                                 |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Femur, Hyperostosis                  |                                                                          |             
      Turbinate, Hyperostosis              |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Compression                          | 2        2     2        2              2              2                 2|             
      Cyst                                 |          2                                                               |             
      Hemorrhage                           | 2                                                                       2|             
      Hydrocephalus                        |                         2                                                |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  42                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 6| 7| 7| 7| 3| 7| 7| 7| 7| 7| 2| 6| 7| 7| 7|             
                             DAY ON TEST   | 8| 3| 3| 3| 3| 3| 3| 3| 3| 3| 0| 3| 3| 3| 9| 3| 3| 3| 3| 3| 3| 7| 3| 3| 3|             
                                           | 1| 4| 5| 3| 4| 5| 3| 3| 3| 4| 8| 4| 5| 5| 4| 3| 3| 4| 5| 4| 4| 4| 5| 5| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|             
    150 PPM                                | 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1|             
                                           | 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7|             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Foreign Body                         | 2                                                                        |             
      Infiltration Cellular, Lymphocyte    |                                                       3           2      |             
      Inflammation                         | 2                                                           2            |             
      Metaplasia, Squamous                 |                                                                          |             
      Epithelium, Hyperplasia              |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                               3                             3            |             
      Hemorrhage                           |             1                                            1               |             
      Infiltration Cellular, Histiocyte    |             1                                                            |             
      Inflammation                         |                               2                                2         |             
      Alveolar Epithelium, Hyperplasia     | 1     2  2  1  2  2  2  2  2     3  1        2  3  3  2           3     1|             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Foreign Body                         |                                                                          |             
      Hemorrhage                           |                                                                          |             
      Inflammation                         |                         2                    2        3                  |             
      Goblet Cell, Hyperplasia             |                                           1                              |             
      Nasolacrimal Duct, Inflammation      |                                                                          |             
      Olfactory Epithelium, Cytoplasmic    |                                                                          |             
          Alteration                       |                                                          2              2|             
      Respiratory Epithelium, Hyperplasia  |                                                       4                  |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Ear                                     |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Mineralization                       | 1                             1     1     1                       1      |             
      Nephropathy, Chronic                 | 1     1  1  2  1  1  1        1        3  1  2  1  1  2        1  1  1  2|             
      Pigmentation                         |                         1                                                |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  M  +|             
      Arteriole, Inflammation              |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  43                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 5| 7| 7| 7| 7| 7| 7| 5| 6| 6| 7| 7| 7| 6| 4| 6| 7| 7| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 3| 0| 3| 3| 3| 3| 3| 3| 3| 1| 3| 3| 3| 3| 2| 8| 9| 3| 0| 3| 3| 5| 5| 5| 5|             
                                           | 3| 0| 4| 4| 3| 3| 5| 5| 3| 7| 0| 4| 3| 3| 2| 3| 6| 4| 5| 3| 3| 7| 7| 7| 7|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|             
    150 PPM                                | 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4|             
                                           | 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                                 4                        |             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  A  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  A  +  A  +  +  +  A  +  +  +  A  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  A  +  +  +  A  +  +  +  A  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Basophilic Focus                     |                                                                          |             
      Basophilic Focus, Multiple           | 2     2  2  2  1  1  2     2  2  2  2  2  2        1     1  1  1  2  1  1|             
      Clear Cell Focus                     |                1                                                         |             
      Clear Cell Focus, Multiple           |                                                                          |             
      Congestion                           |                               1                       2                  |             
      Developmental Malformation           |          1                                                               |             
      Eosinophilic Focus                   |                                                                          |             
      Eosinophilic Focus, Multiple         |                2                                                         |             
      Fatty Change                         |                                                 3           2            |             
      Hemorrhage                           |                                        2                                 |             
      Hepatodiaphragmatic Nodule           |                                        2                                 |             
      Infiltration Cellular, Lymphocyte    |                                                                          |             
      Inflammation                         |                                                                          |             
      Necrosis                             |                            1                    3                        |             
      Pigmentation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Mesentery                               |                                                          +               |             
      Fat, Necrosis                        |                                                          3               |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Ectopic Liver                        |    1                                                                     |             
      Acinar Cell, Atrophy                 |    1        1           2        1              2  2  2  1  2  2  2  1   |             
                                            __________________________________________________________________________|             
   Pharynx                                 |                                                                          |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                                 2                        |             
      Inflammation                         |                                                 2                        |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Ulcer                                |                         2                                                |             
                                            __________________________________________________________________________|             
   Tongue                                  |                            +                                             |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       |       1  2  1  1  1  1        2  1     1        2  2  1  1     1  1  1  1|             
      Atrium, Thrombosis                   |                                                 2                        |             
      Endocardium, Proliferation           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  44                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 5| 7| 7| 7| 7| 7| 7| 5| 6| 6| 7| 7| 7| 6| 4| 6| 7| 7| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 3| 0| 3| 3| 3| 3| 3| 3| 3| 1| 3| 3| 3| 3| 2| 8| 9| 3| 0| 3| 3| 5| 5| 5| 5|             
                                           | 3| 0| 4| 4| 3| 3| 5| 5| 3| 7| 0| 4| 3| 3| 2| 3| 6| 4| 5| 3| 3| 7| 7| 7| 7|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|             
    150 PPM                                | 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4|             
                                           | 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2|             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM - cont                   |                                                                          |             
                                           |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |       2  2           2                 2        3                        |             
      Congestion                           |                                                                          |             
      Degeneration                         |                                                                          |             
      Hemorrhage                           |                                                    2                     |             
      Hyperplasia                          |             1                                                            |             
      Hypertrophy                          |                                                          1               |             
      Infiltration Cellular, Lymphocyte    |                         1                                                |             
      Vacuolization Cytoplasmic            |       2                 2              2           2                     |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                               2        2        2                        |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      |                                                                          |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          | 4                                                                        |             
      Congestion                           |                                                                          |             
      Pars Distalis, Angiectasis           |                3                       4                 3               |             
      Pars Distalis, Cyst                  |             2  2  2              2                       2  2  2         |             
      Pars Distalis, Hyperplasia           | 2           1           2     2     2  2                    3        2   |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  |    1                                2        1                          1|             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Clitoral Gland                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Ectasia                              | 3  3  1  3     2     3  2        2        2  2     3     2  2  3  2  2   |             
      Hyperplasia                          |                                     2     2                              |             
      Inflammation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                              2                           |             
                                            __________________________________________________________________________|             
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Cyst                                 |                                                 2                        |             
      Dilatation                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                               2                 3                        |             
      Myelofibrosis                        |          3                                                     1         |             
                                            __________________________________________________________________________|             
   Lymph Node                              |                   +                                                      |             
      Axillary, Hyperplasia, Lymphoid      |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  45                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 5| 7| 7| 7| 7| 7| 7| 5| 6| 6| 7| 7| 7| 6| 4| 6| 7| 7| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 3| 0| 3| 3| 3| 3| 3| 3| 3| 1| 3| 3| 3| 3| 2| 8| 9| 3| 0| 3| 3| 5| 5| 5| 5|             
                                           | 3| 0| 4| 4| 3| 3| 5| 5| 3| 7| 0| 4| 3| 3| 2| 3| 6| 4| 5| 3| 3| 7| 7| 7| 7|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|             
    150 PPM                                | 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4|             
                                           | 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Lumbar, Pigmentation                 |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Bronchial                   | M  +  +  +  +  +  M  +  +  M  +  +  +  M  +  +  +  +  M  M  M  +  +  +  +|             
      Hemorrhage                           |          1  2                                   1  2           1     2   |             
      Pigmentation                         |       1        1                    2        1                           |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                1                                                         |             
      Hyperplasia, Plasma Cell             |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |    2           2        2        1                                       |             
      Pigmentation                         |                1                                                         |             
                                            __________________________________________________________________________|             
   Lymph Node, Mediastinal                 | +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           | 1     2  2  3  2        2  2        2           2  2        1  2  1  2   |             
      Pigmentation                         |       2  2  2  2  1                 2  1                    1            |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                             2            |             
      Developmental Malformation           |                                                                          |             
      Hematopoietic Cell Proliferation     |                               2                 2                    1   |             
      Pigmentation                         |    2                    2                    2                           |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |    1  1     2           4  2        2  2        3  2     2               |             
      Congestion                           |                               3                                          |             
      Cyst                                 |                                                                          |             
      Hemorrhage                           |                            1              3                              |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Galactocele                          |                                                                          |             
      Hyperplasia                          |                                                 2                        |             
      Inflammation                         |                                                    2                     |             
      Lactation                            |    2                          2              2        2  2               |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              | 3                                                                        |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Femur, Hyperostosis                  |          4        3  2        2                                          |             
      Turbinate, Hyperostosis              |                   3  2                                                   |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Compression                          |    3                                      2  3                           |             
      Cyst                                 |                                                                          |             
      Hemorrhage                           |                                                                          |             
      Hydrocephalus                        |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  46                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 5| 7| 7| 7| 7| 7| 7| 5| 6| 6| 7| 7| 7| 6| 4| 6| 7| 7| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 3| 0| 3| 3| 3| 3| 3| 3| 3| 1| 3| 3| 3| 3| 2| 8| 9| 3| 0| 3| 3| 5| 5| 5| 5|             
                                           | 3| 0| 4| 4| 3| 3| 5| 5| 3| 7| 0| 4| 3| 3| 2| 3| 6| 4| 5| 3| 3| 7| 7| 7| 7|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|             
    150 PPM                                | 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4|             
                                           | 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2|             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Foreign Body                         |                                                                          |             
      Infiltration Cellular, Lymphocyte    | 2                                                                        |             
      Inflammation                         |          3           1     2     1                                       |             
      Metaplasia, Squamous                 |                            2                                             |             
      Epithelium, Hyperplasia              |    2                                                                     |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Hemorrhage                           |                                                       1           1      |             
      Infiltration Cellular, Histiocyte    |                1                                                         |             
      Inflammation                         |                                                 2                        |             
      Alveolar Epithelium, Hyperplasia     | 2  2  1  2        1  1     2     2        2     2  2     2  2     2  2  2|             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                               2                                          |             
      Foreign Body                         |             2                                                            |             
      Hemorrhage                           |             2                                                            |             
      Inflammation                         |       1        1                    2                                    |             
      Goblet Cell, Hyperplasia             |                                                                          |             
      Nasolacrimal Duct, Inflammation      |                1                    2                                    |             
      Olfactory Epithelium, Cytoplasmic    |                                                                          |             
          Alteration                       |                         2                                      2  2  1  1|             
      Respiratory Epithelium, Hyperplasia  |                                                                          |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Ear                                     |                                                 +                        |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                         2                                                |             
      Mineralization                       |    1                    1                    2                 1  1  1  1|             
      Nephropathy, Chronic                 | 2  1  1  1  1  1  1  1     1     2  1  2  1     1  2     2  1  1  1  1  1|             
      Pigmentation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  M  +  +  +|             
      Arteriole, Inflammation              |                                                    2                     |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  47                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 7| 7| 7| 7| 7| 7|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 4| 4| 4| 4| 4| 4|                                                        |      A     |
    150 PPM                                | 4| 4| 4| 4| 4| 4|                                                        |      L     |
                                           | 3| 4| 5| 6| 7| 8|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM                         |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Esophagus                               | +  +  +  +  +  +                                                         |  56        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  +                                                         |  54        |
      Abscess                              |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +                                                         |  54        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  +  +  +                                                         |  53        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  +  +                                                         |  54        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  +  +  +                                                         |  50        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  +  +  +  +                                                         |  51        |
                                            __________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +                                                         |  56        |
      Basophilic Focus                     |    1  1     1                                                            |      7  1.1|
      Basophilic Focus, Multiple           | 1        2                                                               |     40  1.8|
      Clear Cell Focus                     |                                                                          |      2  1.0|
      Clear Cell Focus, Multiple           |                                                                          |      1  1.0|
      Congestion                           |                                                                          |      4  1.5|
      Developmental Malformation           |                                                                          |      2  1.5|
      Eosinophilic Focus                   |                                                                          |      2  2.0|
      Eosinophilic Focus, Multiple         |                                                                          |      1  2.0|
      Fatty Change                         |                                                                          |      4  2.0|
      Hemorrhage                           |                                                                          |      1  2.0|
      Hepatodiaphragmatic Nodule           |                X                                                         |      6  2.0|
      Infiltration Cellular, Lymphocyte    | 2                                                                        |      1  2.0|
      Inflammation                         |                                                                          |      2  1.5|
      Necrosis                             |                                                                          |      3  2.0|
      Pigmentation                         |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Mesentery                               |                                                                          |   2        |
      Fat, Necrosis                        |                                                                          |      2  3.0|
                                            __________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +                                                         |  56        |
      Ectopic Liver                        | 1                                                                        |      2  1.0|
      Acinar Cell, Atrophy                 |             2  1                                                         |     25  1.6|
                                            __________________________________________________________________________|____________|
   Pharynx                                 |                                                                          |   1        |
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +                                                         |  56        |
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +                                                         |  56        |
      Hyperplasia                          |                                                                          |      1  2.0|
      Inflammation                         |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +                                                         |  56        |
      Ulcer                                |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Tongue                                  |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  48                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 7| 7| 7| 7| 7| 7|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 4| 4| 4| 4| 4| 4|                                                        |      A     |
    150 PPM                                | 4| 4| 4| 4| 4| 4|                                                        |      L     |
                                           | 3| 4| 5| 6| 7| 8|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 CARDIOVASCULAR SYSTEM - cont              |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +                                                         |  56        |
      Cardiomyopathy                       | 1  1     1  1  1                                                         |     41  1.4|
      Atrium, Thrombosis                   |                                                                          |      2  2.5|
      Endocardium, Proliferation           |                                                                          |      1  3.0|
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +                                                         |  56        |
      Angiectasis                          |                                                                          |     10  2.2|
      Congestion                           |                                                                          |      1  3.0|
      Degeneration                         |                                                                          |      1  3.0|
      Hemorrhage                           |                                                                          |      4  2.0|
      Hyperplasia                          |                                                                          |      3  1.3|
      Hypertrophy                          |                                                                          |      1  1.0|
      Infiltration Cellular, Lymphocyte    |                                                                          |      1  1.0|
      Vacuolization Cytoplasmic            |                                                                          |     10  2.0|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +                                                         |  56        |
      Hyperplasia                          |                                                                          |      5  1.8|
                                            __________________________________________________________________________|____________|
   Islets, Pancreatic                      |                                                                          |   1        |
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | +  +  +  +  +  +                                                         |  49        |
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +                                                         |  56        |
      Angiectasis                          |                                                                          |      1  4.0|
      Congestion                           |                                                                          |      1  2.0|
      Pars Distalis, Angiectasis           |                                                                          |      7  3.0|
      Pars Distalis, Cyst                  |                                                                          |      9  2.0|
      Pars Distalis, Hyperplasia           | 2           1  1                                                         |     21  2.0|
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +                                                         |  56        |
      C-Cell, Hyperplasia                  |                                                                          |      6  1.5|
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Clitoral Gland                          | +  +  +  +  +  +                                                         |  56        |
      Ectasia                              | 2     3  3  2  2                                                         |     37  2.4|
      Hyperplasia                          |                                                                          |      6  2.3|
      Inflammation                         |                                                                          |      2  2.0|
                                            __________________________________________________________________________|____________|
   Ovary                                   | +  +  +  +  +  +                                                         |  56        |
      Cyst                                 |                                                                          |      2  2.0|
                                            __________________________________________________________________________|____________|
   Uterus                                  | +  +  +  +  +  +                                                         |  56        |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  49                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 7| 7| 7| 7| 7| 7|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 4| 4| 4| 4| 4| 4|                                                        |      A     |
    150 PPM                                | 4| 4| 4| 4| 4| 4|                                                        |      L     |
                                           | 3| 4| 5| 6| 7| 8|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 GENITAL SYSTEM - cont                     |                                                                          |            |
                                           |                                                                          |            |
      Angiectasis                          |                                                                          |      1  2.0|
      Cyst                                 |                                                                          |      2  3.0|
      Dilatation                           |                1                                                         |      2  1.5|
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +                                                         |  56        |
      Hyperplasia                          |                1                                                         |      6  2.0|
      Myelofibrosis                        |                                                                          |      2  2.0|
                                            __________________________________________________________________________|____________|
   Lymph Node                              |                                                                          |   3        |
      Axillary, Hyperplasia, Lymphoid      |                                                                          |      1  2.0|
      Lumbar, Pigmentation                 |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Bronchial                   | +  +  +  +  +  +                                                         |  38        |
      Hemorrhage                           | 2  2  3  3  1  2                                                         |     20  1.8|
      Pigmentation                         |                                                                          |      7  1.3|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +                                                         |  53        |
      Hemorrhage                           |                                                                          |      1  1.0|
      Hyperplasia, Plasma Cell             |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +                                                         |  55        |
      Hemorrhage                           | 1                                                                        |      8  1.9|
      Pigmentation                         |                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mediastinal                 | +  +  +  +  +  +                                                         |  53        |
      Hemorrhage                           | 2  2  2  2  1  1                                                         |     35  1.8|
      Pigmentation                         |                                                                          |     17  1.5|
                                            __________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +                                                         |  56        |
      Congestion                           |                                                                          |      1  2.0|
      Developmental Malformation           |                                                                          |      1  2.0|
      Hematopoietic Cell Proliferation     | 1     1        1                                                         |     10  1.5|
      Pigmentation                         |                                                                          |      3  2.0|
                                            __________________________________________________________________________|____________|
   Thymus                                  | +  +  +  +  +  +                                                         |  54        |
      Atrophy                              | 2           1  1                                                         |     24  1.9|
      Congestion                           |                                                                          |      1  3.0|
      Cyst                                 |                                                                          |      1  3.0|
      Hemorrhage                           |    1     1  1                                                            |      7  1.7|
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Mammary Gland                           | +  +  +  +  +  +                                                         |  56        |
      Galactocele                          |                                                                          |      1  3.0|
      Hyperplasia                          |                                                                          |      1  2.0|
      Inflammation                         |                                                                          |      2  2.5|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  50                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 7| 7| 7| 7| 7| 7|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 4| 4| 4| 4| 4| 4|                                                        |      A     |
    150 PPM                                | 4| 4| 4| 4| 4| 4|                                                        |      L     |
                                           | 3| 4| 5| 6| 7| 8|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 INTEGUMENTARY SYSTEM - cont               |                                                                          |            |
                                           |                                                                          |            |
      Lactation                            |                                                                          |      8  1.9|
                                            __________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +                                                         |  56        |
      Abscess                              |                                                                          |      1  3.0|
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +                                                         |  56        |
      Femur, Hyperostosis                  | 2                                                                        |      5  2.6|
      Turbinate, Hyperostosis              |                                                                          |      2  2.5|
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +                                                         |  56        |
      Compression                          |                                                                          |     10  2.2|
      Cyst                                 |                                                                          |      1  2.0|
      Hemorrhage                           |                                                                          |      2  2.0|
      Hydrocephalus                        |                                                                          |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Larynx                                  | +  +  +  +  +  +                                                         |  56        |
      Foreign Body                         |                                                                          |      1  2.0|
      Infiltration Cellular, Lymphocyte    |                                                                          |      3  2.3|
      Inflammation                         |                                                                          |      6  1.8|
      Metaplasia, Squamous                 |                                                                          |      1  2.0|
      Epithelium, Hyperplasia              | 2                                                                        |      2  2.0|
                                            __________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +                                                         |  56        |
      Congestion                           |                                                                          |      2  3.0|
      Hemorrhage                           |    3  1  1  1  1                                                         |      9  1.2|
      Infiltration Cellular, Histiocyte    |                                                                          |      2  1.0|
      Inflammation                         |                                                                          |      3  2.0|
      Alveolar Epithelium, Hyperplasia     |          1     2                                                         |     35  1.9|
                                            __________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +                                                         |  56        |
      Angiectasis                          |                                                                          |      1  2.0|
      Foreign Body                         |                                                                          |      1  2.0|
      Hemorrhage                           |                                                                          |      1  2.0|
      Inflammation                         |                1                                                         |      7  1.7|
      Goblet Cell, Hyperplasia             |       1     1                                                            |      3  1.0|
      Nasolacrimal Duct, Inflammation      |                                                                          |      2  1.5|
      Olfactory Epithelium, Cytoplasmic    |                                                                          |            |
          Alteration                       |          2  1                                                            |      9  1.7|
      Respiratory Epithelium, Hyperplasia  |             2                                                            |      2  3.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  51                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 7| 7| 7| 7| 7| 7|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 4| 4| 4| 4| 4| 4|                                                        |      A     |
    150 PPM                                | 4| 4| 4| 4| 4| 4|                                                        |      L     |
                                           | 3| 4| 5| 6| 7| 8|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 RESPIRATORY SYSTEM - cont                 |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +                                                         |  56        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Ear                                     |          +                                                               |   2        |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +                                                         |  56        |
      Congestion                           |                                                                          |      1  2.0|
      Mineralization                       | 2  1  1     1  1                                                         |     17  1.1|
      Nephropathy, Chronic                 | 1     1  1  1  1                                                         |     44  1.3|
      Pigmentation                         |                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  +  +  +                                                         |  52        |
      Arteriole, Inflammation              |                                                                          |      1  2.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  52                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 6| 6| 6| 7| 7| 7| 6| 5| 4| 7| 7| 4| 7| 5| 7| 6| 7| 6| 5| 7| 7| 6| 6| 6|             
                             DAY ON TEST   | 4| 6| 3| 9| 2| 2| 3| 4| 3| 9| 3| 2| 2| 3| 8| 2| 9| 3| 3| 3| 2| 3| 6| 4| 8|             
                                           | 1| 6| 9| 2| 9| 9| 0| 0| 3| 8| 0| 9| 7| 0| 3| 9| 5| 0| 1| 2| 6| 0| 7| 4| 4|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    CONTROL                                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A|             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +|             
      Hemorrhage                           |                                                                          |             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Basophilic Focus                     |             1     1                             1           1            |             
      Basophilic Focus, Multiple           |                                           1                              |             
      Clear Cell Focus                     |                                                                          |             
      Clear Cell Focus, Multiple           |                                                                          |             
      Congestion                           |                                     2                                    |             
      Cytoplasmic Alteration               |                      3                                                   |             
      Degeneration, Cystic                 |                                        2                    2           1|             
      Developmental Malformation           |                                                                          |             
      Eosinophilic Focus                   |                               3        2                                 |             
      Eosinophilic Focus, Multiple         |                                                             2            |             
      Fatty Change                         |                                                                          |             
      Hemorrhage                           |                         1                                                |             
      Hepatodiaphragmatic Nodule           |                                                 3                        |             
      Inflammation                         |                                                                          |             
      Mixed Cell Focus                     |                                                                          |             
      Mixed Cell Focus, Multiple           |                                                                          |             
      Necrosis                             |                      2                                                   |             
      Bile Duct, Hyperplasia               |                                        2                                 |             
                                            __________________________________________________________________________|             
   Mesentery                               |       +                                +     +        +  +        +      |             
      Fat, Necrosis                        |       3                                2     2        3  1        3      |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    |                         2                                                |             
      Acinar Cell, Atrophy                 | 3  2  2  1     2  2  2     2           2     3  2  1  2  2  1     2     2|             
      Acinar Cell, Hyperplasia             |                                                 3                        |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                                                         2|             
      Inflammation                         |                                                                          |             
      Ulcer                                |          3                 2                                         2  3|             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Necrosis                             |                            1                          3                 2|             
      Ulcer                                |                                                                          |             
      Ulcer, Multiple                      |       3                                      2                           |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  53                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 6| 6| 6| 7| 7| 7| 6| 5| 4| 7| 7| 4| 7| 5| 7| 6| 7| 6| 5| 7| 7| 6| 6| 6|             
                             DAY ON TEST   | 4| 6| 3| 9| 2| 2| 3| 4| 3| 9| 3| 2| 2| 3| 8| 2| 9| 3| 3| 3| 2| 3| 6| 4| 8|             
                                           | 1| 6| 9| 2| 9| 9| 0| 0| 3| 8| 0| 9| 7| 0| 3| 9| 5| 0| 1| 2| 6| 0| 7| 4| 4|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    CONTROL                                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM - cont              |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       |          2  2  2  2  2        2  2  2  2  2  1  3  2  1  1  2  1        3|             
      Atrium, Dilatation                   |                                                                          |             
      Atrium, Thrombosis                   |          3                                   3                           |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                           2                              |             
      Cytoplasmic Alteration               |                                                                         2|             
      Degeneration                         |                                              2              2            |             
      Hyperplasia                          |                                        1                                2|             
      Hypertrophy                          |                                                             2            |             
      Vacuolization Cytoplasmic            |             1     2     2                                                |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Hyperplasia                          |       2        1                       1  3  2  2  2        2            |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      |                                        +  +        +  +                  |             
      Hyperplasia                          |                                        2              3                  |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  M  M  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |    2                                               2                    3|             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Pars Distalis, Angiectasis           |                                        2                                 |             
      Pars Distalis, Cyst                  |                                                                          |             
      Pars Distalis, Hyperplasia           |                               3        2        3  2                     |             
      Pars Intermedia, Angiectasis         |                                                                          |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  |    2                                   1        3  2  1                  |             
      Follicle, Dilatation                 |                      2                                                   |             
      Follicular Cell, Hyperplasia         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Tissue NOS                              |                                                                   +      |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Coagulating Gland                       |       +                                                  +               |             
                                            __________________________________________________________________________|             
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                                                 3                        |             
      Granuloma Sperm                      |                                                                          |             
      Hypospermia                          | 3        4  3     2           4  4     4  4  4     3  4     2  3     4   |             
      Inflammation, Chronic                |       2                                                                  |             
      Inflammation                         |                      2                                                   |             
      Spermatocele                         |       4                                                                  |             
                                            __________________________________________________________________________|             
   Penis                                   |                                                                          |             
                                            __________________________________________________________________________|             
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  54                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 6| 6| 6| 7| 7| 7| 6| 5| 4| 7| 7| 4| 7| 5| 7| 6| 7| 6| 5| 7| 7| 6| 6| 6|             
                             DAY ON TEST   | 4| 6| 3| 9| 2| 2| 3| 4| 3| 9| 3| 2| 2| 3| 8| 2| 9| 3| 3| 3| 2| 3| 6| 4| 8|             
                                           | 1| 6| 9| 2| 9| 9| 0| 0| 3| 8| 0| 9| 7| 0| 3| 9| 5| 0| 1| 2| 6| 0| 7| 4| 4|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    CONTROL                                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Abscess                              |                                                                          |             
      Ectasia                              | 3  1  2  3  2  3  3     2  2  2     3  1     3  3     2  2  3     2     3|             
      Inflammation                         |                1              2                                          |             
                                            __________________________________________________________________________|             
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |          4                                                               |             
      Atrophy                              |                                                                         2|             
      Concretion                           |                                                          2               |             
      Hyperplasia                          |             1           2                          1        1            |             
      Inflammation                         |    3  3              3  2  2              3     1     2  1  2     3  2  2|             
      Epithelium, Cytoplasmic Alteration   |                                        3                                 |             
                                            __________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Cellular                   | 3  4  2  4                    4  4        3  3  4  3  4  3  3  3         |             
      Inflammation                         |             1                                                            |             
                                            __________________________________________________________________________|             
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |             4  2     3                                      1  3         |             
      Arteriole, Inflammation              |                   2                                                      |             
      Bilateral, Atrophy                   |       3  3                             4  4           3  3              2|             
      Interstitial Cell, Hyperplasia       |          2     2           1        1     2           2           1     1|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                4     3        3  2     3  4     3                        |             
                                            __________________________________________________________________________|             
   Lymph Node                              |          +                                +                          +   |             
      Lumbar, Hyperplasia, Plasma Cell     |                                           4                              |             
                                            __________________________________________________________________________|             
   Lymph Node, Bronchial                   | +  +  +  M  +  +  +  M  +  +  +  +  +  +  +  M  M  +  +  +  +  +  +  +  M|             
      Hemorrhage                           |             3                                               2            |             
      Hyperplasia, Plasma Cell             |                                           3                              |             
      Pigmentation                         |             2                                                            |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                     3           2                        |             
      Hyperplasia, Plasma Cell             |                                        2                                 |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                                             2            |             
                                            __________________________________________________________________________|             
   Lymph Node, Mediastinal                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |             4     1     3           3           1           3            |             
      Hyperplasia, Plasma Cell             |                2     1                    3                              |             
      Pigmentation                         |             2           3                       2           2           1|             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Hematopoietic Cell Proliferation     |                      3                    3                              |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  M  +  +  +  +  +  +  M  +  M  +  +  +  M  +  +  +  +  +  +  M  +  +|             
      Atrophy                              | 3  3        1  2  2  4  3                 3     3        4  2           4|             
      Hemorrhage                           |                                     3                                    |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  55                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 6| 6| 6| 7| 7| 7| 6| 5| 4| 7| 7| 4| 7| 5| 7| 6| 7| 6| 5| 7| 7| 6| 6| 6|             
                             DAY ON TEST   | 4| 6| 3| 9| 2| 2| 3| 4| 3| 9| 3| 2| 2| 3| 8| 2| 9| 3| 3| 3| 2| 3| 6| 4| 8|             
                                           | 1| 6| 9| 2| 9| 9| 0| 0| 3| 8| 0| 9| 7| 0| 3| 9| 5| 0| 1| 2| 6| 0| 7| 4| 4|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    CONTROL                                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  M  +  +  +  +  +  +  M|             
      Galactocele                          |                                                                          |             
      Hyperplasia                          |                2                                                         |             
      Inflammation                         |             2                                                            |             
      Lactation                            |    1           2  3  2                    3  2        2     3     2      |             
      Pigmentation                         |                                                          2     3         |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation                         |                                                          1               |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cranium, Hemorrhage                  |                                     2                                    |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Compression                          |    3              2  1                    3  2              3            |             
      Hemorrhage                           |                                     1                                    |             
      Hydrocephalus                        |                         3                                                |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Foreign Body                         | 3                                                                        |             
      Infiltration Cellular, Lymphocyte    |                                           2                              |             
      Inflammation                         | 2                                                                        |             
      Epithelium, Hyperplasia              |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                     3                                   3|             
      Hemorrhage                           |                                     1                                    |             
      Inflammation                         |                                              2                          1|             
      Leukocytosis                         |                                           2                              |             
      Alveolar Epithelium, Hyperplasia     |    1                                                                     |             
      Bronchus, Hyperplasia                |                                                                          |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                      3     2                 2                           |             
      Foreign Body                         |                                  3                 2  2        1         |             
      Hemorrhage                           | 2                       2           2                                    |             
      Inflammation                         |                                  2     1        2  2  3        1         |             
      Polyp Inflammatory                   |                                                                          |             
      Respiratory Epithelium, Hyperplasia  |          2                                      2                        |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Eye                                     |                                                          +               |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  56                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 6| 6| 6| 7| 7| 7| 6| 5| 4| 7| 7| 4| 7| 5| 7| 6| 7| 6| 5| 7| 7| 6| 6| 6|             
                             DAY ON TEST   | 4| 6| 3| 9| 2| 2| 3| 4| 3| 9| 3| 2| 2| 3| 8| 2| 9| 3| 3| 3| 2| 3| 6| 4| 8|             
                                           | 1| 6| 9| 2| 9| 9| 0| 0| 3| 8| 0| 9| 7| 0| 3| 9| 5| 0| 1| 2| 6| 0| 7| 4| 4|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    CONTROL                                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM - cont              |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                     2                                    |             
      Cyst                                 |                                                                         3|             
      Hydronephrosis                       |                                                                          |             
      Nephropathy, Chronic                 | 2  2  2  2  2  2  3  2  2  2  2  2  1  2  2  2  3     2     3     2  2  4|             
      Pigmentation                         |          3                                               2               |             
      Pelvis, Hyperplasia                  |                                                                          |             
      Renal Tubule, Cytoplasmic Alteration |                                                                          |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Calculus Micro Observation Only      |                                                                          |             
      Dilatation                           |                            3              3              3               |             
      Inflammation                         |                                                                          |             
      Transitional Epithelium, Hyperplasia |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  57                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 4| 7| 6| 6| 7| 6| 6| 7| 4| 6| 6| 7| 5| 6| 6| 5| 7| 6| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 3| 9| 3| 6| 8| 3| 5| 1| 2| 1| 1| 6| 3| 2| 6| 2| 6| 2| 3| 3| 3| 5| 5| 5| 5|             
                                           | 0| 5| 0| 5| 1| 0| 4| 1| 9| 5| 7| 6| 0| 5| 6| 4| 3| 9| 9| 0| 0| 6| 6| 6| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    CONTROL                                | 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  A  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  A  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  A  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  A  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                                                          |             
                                            __________________________________________________________________________|             
   Liver                                   | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Basophilic Focus                     |                               1        1                       1        1|             
      Basophilic Focus, Multiple           |                2                    2     1                 1            |             
      Clear Cell Focus                     |                                                                          |             
      Clear Cell Focus, Multiple           | 2                                                        1               |             
      Congestion                           |             3     2                                                      |             
      Cytoplasmic Alteration               |                                                                          |             
      Degeneration, Cystic                 |                                                          2               |             
      Developmental Malformation           |                               2                                          |             
      Eosinophilic Focus                   |                                                          2        2  1   |             
      Eosinophilic Focus, Multiple         |                                                                          |             
      Fatty Change                         |                               2     2  1                       1     1   |             
      Hemorrhage                           |                                                                         1|             
      Hepatodiaphragmatic Nodule           |                                                                          |             
      Inflammation                         |                                                                   1      |             
      Mixed Cell Focus                     |                                                       2                  |             
      Mixed Cell Focus, Multiple           |                                     2                       3            |             
      Necrosis                             |          2                                                               |             
      Bile Duct, Hyperplasia               |                         2                          3                     |             
                                            __________________________________________________________________________|             
   Mesentery                               |                                                                          |             
      Fat, Necrosis                        |                                                                          |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    |                                                                          |             
      Acinar Cell, Atrophy                 |       3     2  3  2        2  2  3        2  2        2  2           1  2|             
      Acinar Cell, Hyperplasia             |                                                                          |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |          2              3     2                                          |             
      Inflammation                         |                               2                                          |             
      Ulcer                                |                         3                                                |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Necrosis                             |                                                                          |             
      Ulcer                                |          3                                                               |             
      Ulcer, Multiple                      |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  58                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 4| 7| 6| 6| 7| 6| 6| 7| 4| 6| 6| 7| 5| 6| 6| 5| 7| 6| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 3| 9| 3| 6| 8| 3| 5| 1| 2| 1| 1| 6| 3| 2| 6| 2| 6| 2| 3| 3| 3| 5| 5| 5| 5|             
                                           | 0| 5| 0| 5| 1| 0| 4| 1| 9| 5| 7| 6| 0| 5| 6| 4| 3| 9| 9| 0| 0| 6| 6| 6| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    CONTROL                                | 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM - cont              |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       | 2  2  2     2  2  1  1        1     2  1  3  2        2  2  2  1  2     1|             
      Atrium, Dilatation                   |       2                                                                  |             
      Atrium, Thrombosis                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Cytoplasmic Alteration               |                                                                          |             
      Degeneration                         |                                                 2                        |             
      Hyperplasia                          |                1              1                    2  2  1               |             
      Hypertrophy                          |                                                                          |             
      Vacuolization Cytoplasmic            |                                     2                 1  2     2         |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +|             
      Angiectasis                          |                                                                         2|             
      Hyperplasia                          |       1  2  2  1                                   3  1  1               |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      |       +        +     +                                      +            |             
      Hyperplasia                          |       2                                                     2            |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | M  +  +  +  +  +  +  +  M  +  +  +  M  M  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                                             2            |             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Pars Distalis, Angiectasis           |                                                                          |             
      Pars Distalis, Cyst                  |                         2                                   2            |             
      Pars Distalis, Hyperplasia           |                                                          1  3     1  2  2|             
      Pars Intermedia, Angiectasis         |                                                                         2|             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  |                                        3                                1|             
      Follicle, Dilatation                 |                      2                    2                              |             
      Follicular Cell, Hyperplasia         | 2                                                                        |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Tissue NOS                              |                            +                                             |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Coagulating Gland                       |                                                                          |             
                                            __________________________________________________________________________|             
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                                                                          |             
      Granuloma Sperm                      |                               3                                          |             
      Hypospermia                          | 4        4              4                    3           2  4            |             
      Inflammation, Chronic                |                                                                          |             
      Inflammation                         |                                           3                              |             
      Spermatocele                         |                   3                                                      |             
                                            __________________________________________________________________________|             
   Penis                                   |                                                                          |             
                                            __________________________________________________________________________|             
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  59                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 4| 7| 6| 6| 7| 6| 6| 7| 4| 6| 6| 7| 5| 6| 6| 5| 7| 6| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 3| 9| 3| 6| 8| 3| 5| 1| 2| 1| 1| 6| 3| 2| 6| 2| 6| 2| 3| 3| 3| 5| 5| 5| 5|             
                                           | 0| 5| 0| 5| 1| 0| 4| 1| 9| 5| 7| 6| 0| 5| 6| 4| 3| 9| 9| 0| 0| 6| 6| 6| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    CONTROL                                | 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Abscess                              |                         4                                                |             
      Ectasia                              |    3     2  2  2  3  3        3     2  2  3  2  2  3     3  2     3  2  1|             
      Inflammation                         |       2                                         1        2  2        2  2|             
                                            __________________________________________________________________________|             
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                                                          |             
      Atrophy                              |                                                                          |             
      Concretion                           |    1                       1           2                                 |             
      Hyperplasia                          |                                                          1               |             
      Inflammation                         |    2     2           3     2  4        2  2  2  2     2  1     2     3  2|             
      Epithelium, Cytoplasmic Alteration   |                                                                          |             
                                            __________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Cellular                   | 3     4  3           3  4        3     3                    3            |             
      Inflammation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                4     2                    3                              |             
      Arteriole, Inflammation              |                                                                          |             
      Bilateral, Atrophy                   |          4        4     3                                                |             
      Interstitial Cell, Hyperplasia       |                2                 1              1     1              1  1|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                               3     2           3  2  3  2              1|             
                                            __________________________________________________________________________|             
   Lymph Node                              |                         +        +                                       |             
      Lumbar, Hyperplasia, Plasma Cell     |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Bronchial                   | M  +  +  +  +  M  +  +  +  +  +  +  M  +  +  +  +  +  +  M  +  +  +  +  +|             
      Hemorrhage                           |             2                                                  1     2  1|             
      Hyperplasia, Plasma Cell             |                                                                          |             
      Pigmentation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |             2                                                           1|             
      Hyperplasia, Plasma Cell             |                                     2           2                        |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                3  2                                                      |             
                                            __________________________________________________________________________|             
   Lymph Node, Mediastinal                 | +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           | 1           2  1  4        2        1     1                    1  1  2  2|             
      Hyperplasia, Plasma Cell             |                                                                          |             
      Pigmentation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                             2            |             
      Hematopoietic Cell Proliferation     |                   1                                                      |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |    4  2  3  3     3  3        3     1  3  2  3  2        2  2  2  2  3   |             
      Hemorrhage                           |             3     1                                                      |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  60                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 4| 7| 6| 6| 7| 6| 6| 7| 4| 6| 6| 7| 5| 6| 6| 5| 7| 6| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 3| 9| 3| 6| 8| 3| 5| 1| 2| 1| 1| 6| 3| 2| 6| 2| 6| 2| 3| 3| 3| 5| 5| 5| 5|             
                                           | 0| 5| 0| 5| 1| 0| 4| 1| 9| 5| 7| 6| 0| 5| 6| 4| 3| 9| 9| 0| 0| 6| 6| 6| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    CONTROL                                | 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Galactocele                          |             3                                                            |             
      Hyperplasia                          |                                                                          |             
      Inflammation                         |                                                                          |             
      Lactation                            |                3                          3     3  2                     |             
      Pigmentation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation                         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cranium, Hemorrhage                  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Compression                          |                   2                    3  3                              |             
      Hemorrhage                           |             1                                                            |             
      Hydrocephalus                        |                                        3  2     2                        |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Foreign Body                         |                                                                          |             
      Infiltration Cellular, Lymphocyte    |                                                                1         |             
      Inflammation                         |                                        2                                2|             
      Epithelium, Hyperplasia              |                                        2                                 |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |             3     2                                                      |             
      Hemorrhage                           |             2     3                                   2        1        1|             
      Inflammation                         |                                                                          |             
      Leukocytosis                         |                                                                          |             
      Alveolar Epithelium, Hyperplasia     |                            1  1                          2  2            |             
      Bronchus, Hyperplasia                |                            3                                             |             
                                            __________________________________________________________________________|             
   Nose                                    | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                2     2                 3                 3               |             
      Foreign Body                         | 1                                                                        |             
      Hemorrhage                           |                            1                                             |             
      Inflammation                         | 1                                                        2               |             
      Polyp Inflammatory                   |             1                                                            |             
      Respiratory Epithelium, Hyperplasia  |                                                                          |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Eye                                     |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  61                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 4| 7| 6| 6| 7| 6| 6| 7| 4| 6| 6| 7| 5| 6| 6| 5| 7| 6| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 3| 9| 3| 6| 8| 3| 5| 1| 2| 1| 1| 6| 3| 2| 6| 2| 6| 2| 3| 3| 3| 5| 5| 5| 5|             
                                           | 0| 5| 0| 5| 1| 0| 4| 1| 9| 5| 7| 6| 0| 5| 6| 4| 3| 9| 9| 0| 0| 6| 6| 6| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    CONTROL                                | 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM - cont              |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Cyst                                 |                                                                          |             
      Hydronephrosis                       |                               2                                          |             
      Nephropathy, Chronic                 | 2     2  1  2  2  2  1        2     2  2  2  2  2  1  1  2  2  1  2  1  2|             
      Pigmentation                         |          2                                                               |             
      Pelvis, Hyperplasia                  |                               3                                          |             
      Renal Tubule, Cytoplasmic Alteration |                            3                                             |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Calculus Micro Observation Only      |                                                                          |             
      Dilatation                           |                   3                                                      |             
      Inflammation                         |                               2                                          |             
      Transitional Epithelium, Hyperplasia |                               3                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  62                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 6| 6| 6| 6| 6| 6|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0|                                                        |      A     |
    CONTROL                                | 5| 5| 5| 5| 5| 5|                                                        |      L     |
                                           | 1| 2| 3| 4| 5| 6|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM                         |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Esophagus                               | +  +  +  +  +  +                                                         |  55        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  +                                                         |  55        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +                                                         |  54        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  +  +  +                                                         |  54        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  +  +                                                         |  54        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  +  +  +                                                         |  54        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  +  +  +  +                                                         |  53        |
      Hemorrhage                           |    2                                                                     |      1  2.0|
                                            __________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +                                                         |  55        |
      Basophilic Focus                     |          1                                                               |      9  1.0|
      Basophilic Focus, Multiple           | 1                                                                        |      6  1.3|
      Clear Cell Focus                     | 1     1        1                                                         |      3  1.0|
      Clear Cell Focus, Multiple           |                                                                          |      2  1.5|
      Congestion                           |                                                                          |      3  2.3|
      Cytoplasmic Alteration               |                                                                          |      1  3.0|
      Degeneration, Cystic                 |                                                                          |      4  1.8|
      Developmental Malformation           |                                                                          |      1  2.0|
      Eosinophilic Focus                   |                                                                          |      5  2.0|
      Eosinophilic Focus, Multiple         |                                                                          |      1  2.0|
      Fatty Change                         |                                                                          |      5  1.4|
      Hemorrhage                           |                                                                          |      2  1.0|
      Hepatodiaphragmatic Nodule           |                                                                          |      1  3.0|
      Inflammation                         |                                                                          |      1  1.0|
      Mixed Cell Focus                     |                                                                          |      1  2.0|
      Mixed Cell Focus, Multiple           |                                                                          |      2  2.5|
      Necrosis                             |                                                                          |      2  2.0|
      Bile Duct, Hyperplasia               |                                                                          |      3  2.3|
                                            __________________________________________________________________________|____________|
   Mesentery                               |                                                                          |   6        |
      Fat, Necrosis                        |                                                                          |      6  2.3|
                                            __________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +                                                         |  55        |
      Infiltration Cellular, Lymphocyte    |       1                                                                  |      2  1.5|
      Acinar Cell, Atrophy                 | 1     2        2                                                         |     33  2.0|
      Acinar Cell, Hyperplasia             |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +                                                         |  56        |
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +                                                         |  55        |
      Hyperplasia                          |                                                                          |      4  2.3|
      Inflammation                         |                                                                          |      1  2.0|
      Ulcer                                |                                                                          |      5  2.6|
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +                                                         |  55        |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  63                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 6| 6| 6| 6| 6| 6|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0|                                                        |      A     |
    CONTROL                                | 5| 5| 5| 5| 5| 5|                                                        |      L     |
                                           | 1| 2| 3| 4| 5| 6|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM - cont                  |                                                                          |            |
                                           |                                                                          |            |
      Necrosis                             |                                                                          |      3  2.0|
      Ulcer                                |                                                                          |      1  3.0|
      Ulcer, Multiple                      |                                                                          |      2  2.5|
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +                                                         |  56        |
      Cardiomyopathy                       | 2  1  1  1  1  1                                                         |     42  1.7|
      Atrium, Dilatation                   |                                                                          |      1  2.0|
      Atrium, Thrombosis                   |                                                                          |      2  3.0|
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +                                                         |  55        |
      Congestion                           |                                                                          |      1  2.0|
      Cytoplasmic Alteration               |                                                                          |      1  2.0|
      Degeneration                         |                                                                          |      3  2.0|
      Hyperplasia                          |                                                                          |      7  1.4|
      Hypertrophy                          |                                                                          |      1  2.0|
      Vacuolization Cytoplasmic            |                                                                          |      7  1.7|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +                                                         |  54        |
      Angiectasis                          |                                                                          |      1  2.0|
      Hyperplasia                          |                                                                          |     15  1.7|
                                            __________________________________________________________________________|____________|
   Islets, Pancreatic                      |                                                                          |   8        |
      Hyperplasia                          |                                                                          |      4  2.3|
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | +  +  +  +  +  +                                                         |  49        |
      Hyperplasia                          |                                                                          |      4  2.3|
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +                                                         |  55        |
      Pars Distalis, Angiectasis           |                                                                          |      1  2.0|
      Pars Distalis, Cyst                  |                                                                          |      2  2.0|
      Pars Distalis, Hyperplasia           |       2     2                                                            |     11  2.1|
      Pars Intermedia, Angiectasis         |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +                                                         |  55        |
      C-Cell, Hyperplasia                  | 1                                                                        |      8  1.8|
      Follicle, Dilatation                 |             2                                                            |      4  2.0|
      Follicular Cell, Hyperplasia         |                                                                          |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Tissue NOS                              | +                                                                        |   3        |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  64                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 6| 6| 6| 6| 6| 6|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0|                                                        |      A     |
    CONTROL                                | 5| 5| 5| 5| 5| 5|                                                        |      L     |
                                           | 1| 2| 3| 4| 5| 6|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 GENITAL SYSTEM - cont                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Coagulating Gland                       |                                                                          |   2        |
                                            __________________________________________________________________________|____________|
   Epididymis                              | +  +  +  +  +  +                                                         |  56        |
      Atrophy                              |                                                                          |      1  3.0|
      Granuloma Sperm                      |                                                                          |      1  3.0|
      Hypospermia                          |                                                                          |     20  3.5|
      Inflammation, Chronic                |                                                                          |      1  2.0|
      Inflammation                         |                                                                          |      2  2.5|
      Spermatocele                         |                                                                          |      2  3.5|
                                            __________________________________________________________________________|____________|
   Penis                                   |    +                                                                     |   1        |
                                            __________________________________________________________________________|____________|
   Preputial Gland                         | +  +  +  +  +  +                                                         |  54        |
      Abscess                              |                                                                          |      1  4.0|
      Ectasia                              | 1  3  3  3  3  2                                                         |     43  2.4|
      Inflammation                         | 1     1  1                                                               |     11  1.5|
                                            __________________________________________________________________________|____________|
   Prostate                                | +  +  +  +  +  +                                                         |  56        |
      Abscess                              |                                                                          |      1  4.0|
      Atrophy                              |                                                                          |      1  2.0|
      Concretion                           | 1              2                                                         |      6  1.5|
      Hyperplasia                          |                                                                          |      5  1.2|
      Inflammation                         | 1  2  2  2     2                                                         |     32  2.2|
      Epithelium, Cytoplasmic Alteration   |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Seminal Vesicle                         | +  +  +  +  +  +                                                         |  55        |
      Depletion Cellular                   |                                                                          |     22  3.3|
      Inflammation                         |                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Testes                                  | +  +  +  +  +  +                                                         |  56        |
      Atrophy                              |                                                                          |      8  2.8|
      Arteriole, Inflammation              |                                                                          |      1  2.0|
      Bilateral, Atrophy                   |                                                                          |     10  3.3|
      Interstitial Cell, Hyperplasia       | 2  2                                                                     |     16  1.4|
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +                                                         |  55        |
      Hyperplasia                          |    1     1                                                               |     16  2.5|
                                            __________________________________________________________________________|____________|
   Lymph Node                              |                                                                          |   5        |
      Lumbar, Hyperplasia, Plasma Cell     |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Bronchial                   | +  +  +  +  +  +                                                         |  47        |
      Hemorrhage                           |    2     2  1  1                                                         |     10  1.7|
      Hyperplasia, Plasma Cell             |                                                                          |      1  3.0|
      Pigmentation                         |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +                                                         |  55        |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  65                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 6| 6| 6| 6| 6| 6|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0|                                                        |      A     |
    CONTROL                                | 5| 5| 5| 5| 5| 5|                                                        |      L     |
                                           | 1| 2| 3| 4| 5| 6|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |            |
                                           |                                                                          |            |
      Hemorrhage                           |    2  2                                                                  |      6  2.0|
      Hyperplasia, Plasma Cell             |                                                                          |      3  2.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +                                                         |  55        |
      Hemorrhage                           |    3                                                                     |      4  2.5|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mediastinal                 | +  +  +  +  +  +                                                         |  55        |
      Hemorrhage                           | 2  3  1  3     2                                                         |     22  2.0|
      Hyperplasia, Plasma Cell             |                                                                          |      3  2.0|
      Pigmentation                         |                                                                          |      5  2.0|
                                            __________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +                                                         |  56        |
      Congestion                           |                                                                          |      1  2.0|
      Hematopoietic Cell Proliferation     |    1                                                                     |      4  2.0|
                                            __________________________________________________________________________|____________|
   Thymus                                  | +  +  +  +  +  +                                                         |  51        |
      Atrophy                              | 2  3  2  1  2  2                                                         |     35  2.5|
      Hemorrhage                           |                                                                          |      3  2.3|
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Mammary Gland                           | +  +  +  +  +  +                                                         |  52        |
      Galactocele                          |                                                                          |      1  3.0|
      Hyperplasia                          |                                                                          |      1  2.0|
      Inflammation                         |                                                                          |      1  2.0|
      Lactation                            |                                                                          |     13  2.4|
      Pigmentation                         |                                                                          |      2  2.5|
                                            __________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +                                                         |  56        |
      Inflammation                         |                                                                          |      1  1.0|
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +                                                         |  56        |
      Cranium, Hemorrhage                  |                                                                          |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +                                                         |  56        |
      Compression                          |                                                                          |      9  2.4|
      Hemorrhage                           |                                                                          |      2  1.0|
      Hydrocephalus                        |                                                                          |      4  2.5|
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Larynx                                  | +  +  +  +  +  +                                                         |  56        |
      Foreign Body                         |                                                                          |      1  3.0|
      Infiltration Cellular, Lymphocyte    |                2                                                         |      3  1.7|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  66                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 6| 6| 6| 6| 6| 6|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0|                                                        |      A     |
    CONTROL                                | 5| 5| 5| 5| 5| 5|                                                        |      L     |
                                           | 1| 2| 3| 4| 5| 6|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 RESPIRATORY SYSTEM - cont                 |                                                                          |            |
                                           |                                                                          |            |
      Inflammation                         |                                                                          |      3  2.0|
      Epithelium, Hyperplasia              |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +                                                         |  56        |
      Congestion                           |                                                                          |      4  2.8|
      Hemorrhage                           |       1     1  1                                                         |      9  1.4|
      Inflammation                         |             1                                                            |      3  1.3|
      Leukocytosis                         |                                                                          |      1  2.0|
      Alveolar Epithelium, Hyperplasia     |                                                                          |      5  1.4|
      Bronchus, Hyperplasia                |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +                                                         |  55        |
      Angiectasis                          |                                                                          |      7  2.4|
      Foreign Body                         |          1                                                               |      6  1.7|
      Hemorrhage                           | 2                                                                        |      5  1.8|
      Inflammation                         |          1                                                               |      9  1.7|
      Polyp Inflammatory                   |                                                                          |      1  1.0|
      Respiratory Epithelium, Hyperplasia  |                                                                          |      2  2.0|
                                            __________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +                                                         |  56        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Eye                                     |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +                                                         |  55        |
      Congestion                           |                                                                          |      1  2.0|
      Cyst                                 |                                                                          |      1  3.0|
      Hydronephrosis                       |                                                                          |      1  2.0|
      Nephropathy, Chronic                 | 2  2  1  1  2  2                                                         |     49  1.9|
      Pigmentation                         |                                                                          |      3  2.3|
      Pelvis, Hyperplasia                  |                                                                          |      1  3.0|
      Renal Tubule, Cytoplasmic Alteration |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  +  +  +                                                         |  56        |
      Calculus Micro Observation Only      |          3                                                               |      1  3.0|
      Dilatation                           |                                                                          |      4  3.0|
      Inflammation                         |                                                                          |      1  2.0|
      Transitional Epithelium, Hyperplasia |                                                                          |      1  3.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  67                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 7| 5| 4| 7| 5| 6| 7| 7| 6| 7| 7| 7| 7| 7| 6| 7| 6| 7| 7| 7| 7| 7| 6|             
                             DAY ON TEST   | 7| 3| 3| 7| 7| 2| 5| 9| 3| 2| 4| 2| 2| 2| 3| 3| 3| 1| 4| 2| 3| 2| 3| 3| 9|             
                                           | 2| 0| 0| 6| 1| 9| 1| 5| 0| 9| 5| 9| 9| 9| 0| 0| 6| 8| 5| 9| 0| 9| 0| 0| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    37.5 PPM                               | 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3|             
                                           | 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Ectasia                              |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  A  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  A  +  A  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  A  +  A  +  +  +  +  +  A|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Basophilic Focus                     | 3  1              1              1                 1                     |             
      Basophilic Focus, Multiple           |                         1     2           3                       1  1   |             
      Clear Cell Focus                     |                                                                          |             
      Clear Cell Focus, Multiple           |    1  2                    1        1        1              1  1         |             
      Congestion                           |                                                                          |             
      Degeneration, Cystic                 |                1     1  3  2  1     1              1                     |             
      Eosinophilic Focus                   |    2                                1     1  1  2                        |             
      Eosinophilic Focus, Multiple         |                                                                      2   |             
      Fatty Change                         | 3        1     1     1     1                       2  4  1              1|             
      Hemorrhage                           |                                                                          |             
      Hepatodiaphragmatic Nodule           |                                        2                                 |             
      Inflammation                         |                                                                   1      |             
      Mixed Cell Focus                     |       2                                                              1   |             
      Necrosis                             |                                                 1     2                  |             
      Pigmentation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Mesentery                               |                                                                          |             
      Fat, Necrosis                        |                                                                          |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation                         |                                                 2                        |             
      Acinar Cell, Atrophy                 |    1  3  2  2  2  1  2     1           1  2  3     2        1  1        2|             
      Duct, Ectasia                        |                                                             2            |             
                                            __________________________________________________________________________|             
   Pharynx                                 |                                     +                                    |             
      Palate, Hyperplasia, Squamous        |                                     4                                    |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                      2                                                   |             
      Inflammation                         |             1        2                                                   |             
      Ulcer                                |                                                       3                  |             
      Ulcer, Multiple                      |                                                          3               |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                                                          |             
      Inflammation                         |                                                                          |             
      Necrosis                             |                                                       2                  |             
      Ulcer, Multiple                      |                                                                          |             
                                            __________________________________________________________________________|             
   Tongue                                  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  68                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 7| 5| 4| 7| 5| 6| 7| 7| 6| 7| 7| 7| 7| 7| 6| 7| 6| 7| 7| 7| 7| 7| 6|             
                             DAY ON TEST   | 7| 3| 3| 7| 7| 2| 5| 9| 3| 2| 4| 2| 2| 2| 3| 3| 3| 1| 4| 2| 3| 2| 3| 3| 9|             
                                           | 2| 0| 0| 6| 1| 9| 1| 5| 0| 9| 5| 9| 9| 9| 0| 0| 6| 8| 5| 9| 0| 9| 0| 0| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    37.5 PPM                               | 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3|             
                                           | 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM - cont                  |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       | 1  2  2     2  1  2  2  2  2  2  1  2  2  2  2  3  2  2  2  2  2  2     3|             
      Inflammation                         |                                                                          |             
      Atrium, Thrombosis                   |                                                                          |             
      Valve, Inflammation                  |                                                                3         |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Degeneration                         |       2                                                                  |             
      Hyperplasia                          |                         2  2                                            2|             
      Hypertrophy                          |                         2                 1                              |             
      Vacuolization Cytoplasmic            | 3     2        3        2  2              2              3  1     2      |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |          1     1     1  2  1  2     2     1  2           1               |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      |                   +     +           +     +  +                       +   |             
      Hyperplasia                          |                                                                      2   |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  +  +  M  +  +  M  +  +  +  +  +  +  +  +  M  M  +  +  +  +  +|             
      Hyperplasia                          |                2     3  2           1           3  3                     |             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                                                          |             
      Pars Distalis, Angiectasis           |                      3                 4           3                 4   |             
      Pars Distalis, Cyst                  |       1                                         4              2         |             
      Pars Distalis, Hemorrhage            |                                                                          |             
      Pars Distalis, Hyperplasia           |                      3     2  3  3                    2     2            |             
      Pars Intermedia, Cyst                |                                                                          |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  |                                                             2           2|             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Granuloma Sperm                      |                                                                         3|             
      Hypospermia                          |    4  4                 3  3  4  4     2     2  4  3  3  4  4     4  4   |             
                                            __________________________________________________________________________|             
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Ectasia                              | 2  2  1  2  3  3     2  2  2     3     2  2     2  3  3        2  1  2  3|             
      Hyperplasia                          |                                                                          |             
      Inflammation                         |    2                 2                                         1         |             
                                            __________________________________________________________________________|             
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Concretion                           |                   1                                                      |             
      Hyperplasia                          |       2                                   2                              |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  69                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 7| 5| 4| 7| 5| 6| 7| 7| 6| 7| 7| 7| 7| 7| 6| 7| 6| 7| 7| 7| 7| 7| 6|             
                             DAY ON TEST   | 7| 3| 3| 7| 7| 2| 5| 9| 3| 2| 4| 2| 2| 2| 3| 3| 3| 1| 4| 2| 3| 2| 3| 3| 9|             
                                           | 2| 0| 0| 6| 1| 9| 1| 5| 0| 9| 5| 9| 9| 9| 0| 0| 6| 8| 5| 9| 0| 9| 0| 0| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    37.5 PPM                               | 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3|             
                                           | 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7|             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Inflammation                         | 3           2                             2     2  2  2        2     2  4|             
      Epithelium, Cytoplasmic Alteration   |                         2                                   2            |             
                                            __________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Cellular                   |    3     3  3     2        4  2  4     2                 3  3     4  3   |             
      Ectasia                              |                                                                         4|             
                                            __________________________________________________________________________|             
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              | 2                                                                 3      |             
      Degeneration                         |                      2                                                   |             
      Hypospermia                          |                                                                          |             
      Arteriole, Inflammation              |                2        3                 2                       2      |             
      Bilateral, Atrophy                   |                                                                          |             
      Bilateral, Degeneration              |                         2                                                |             
      Interstitial Cell, Hyperplasia       |                   2     2              1                       3  2      |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |    2              4     3     4           2     2     3                 2|             
                                            __________________________________________________________________________|             
   Lymph Node, Bronchial                   | +  M  +  M  +  +  +  M  +  +  +  +  +  M  +  +  +  +  +  M  +  +  M  M  M|             
      Hemorrhage                           |                   3     2  2                          3                  |             
      Inflammation                         |                                                                          |             
      Pigmentation                         |                            2                                   1         |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +|             
      Cyst                                 |                                           3                              |             
      Hemorrhage                           |                                                          2               |             
      Hyperplasia, Lymphoid                |                                                                          |             
      Hyperplasia, Plasma Cell             |                                           3                       3      |             
      Pigmentation                         |                                        1                                 |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           | 3              1     1                                         1         |             
                                            __________________________________________________________________________|             
   Lymph Node, Mediastinal                 |    +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |    3  2     1        2     3     1              1  2  1  2  2  1     1   |             
      Hyperplasia, Plasma Cell             |                   2                                                      |             
      Pigmentation                         |    2  2        1     2     2        1  2                 2  1        2   |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                 2                        |             
      Fibrosis                             |    2                                                                     |             
      Hematopoietic Cell Proliferation     |             2     3           3                       2                  |             
      Capsule, Fibrosis                    |       1                                                                  |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              | 3  2     3  3  3  3  2  2  1  1     2  2  2  1  4  2  3  2     2  1     3|             
      Hemorrhage                           |                   3                                   3                  |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  M  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  70                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 7| 5| 4| 7| 5| 6| 7| 7| 6| 7| 7| 7| 7| 7| 6| 7| 6| 7| 7| 7| 7| 7| 6|             
                             DAY ON TEST   | 7| 3| 3| 7| 7| 2| 5| 9| 3| 2| 4| 2| 2| 2| 3| 3| 3| 1| 4| 2| 3| 2| 3| 3| 9|             
                                           | 2| 0| 0| 6| 1| 9| 1| 5| 0| 9| 5| 9| 9| 9| 0| 0| 6| 8| 5| 9| 0| 9| 0| 0| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    37.5 PPM                               | 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3|             
                                           | 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7|             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Galactocele                          | 3                                                                        |             
      Lactation                            |          3  3  2        3              2  2        2     2               |             
      Pigmentation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Pinna, Parakeratosis                 |                      3                                                   |             
      Subcutaneous Tissue, Abscess         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Calvarium, Hemorrhage                |                                                                          |             
      Coccygeal, Fracture                  |                                              3                           |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Compression                          | 3        3  2  3        2              2  3        2     2           3   |             
      Hemorrhage                           |                                                                         1|             
      Hydrocephalus                        |             3                                            2               |             
      Infiltration Cellular, Lymphocyte    |             2                                                            |             
                                            __________________________________________________________________________|             
   Spinal Cord                             |                                                                         +|             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation                         |                                                                          |             
      Epithelium, Hyperplasia              |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                    2                     |             
      Hemorrhage                           |    1  1                    1     1                             1         |             
      Infiltration Cellular, Histiocyte    |                                                                          |             
      Inflammation                         |                                                 1     3     1           1|             
      Leukocytosis                         |                   3                                                      |             
      Necrosis                             |                                                                          |             
      Alveolar Epithelium, Hyperplasia     |                                  2        1              2        3  2   |             
      Artery, Thrombosis                   |                                                       2                  |             
      Goblet Cell, Hyperplasia             |                                                       2                  |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                    2                     |             
      Foreign Body                         |                                                                      1   |             
      Inflammation                         |       2                          2           2              2        1   |             
      Goblet Cell, Hyperplasia             |                                                                          |             
      Nasolacrimal Duct, Inflammation      |                                                          2     2         |             
      Olfactory Epithelium, Cytoplasmic    |                                                                          |             
          Alteration                       |                                              2                           |             
      Respiratory Epithelium, Hyperplasia  |       2                                      2                           |             
      Respiratory Epithelium, Metaplasia,  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  71                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 7| 5| 4| 7| 5| 6| 7| 7| 6| 7| 7| 7| 7| 7| 6| 7| 6| 7| 7| 7| 7| 7| 6|             
                             DAY ON TEST   | 7| 3| 3| 7| 7| 2| 5| 9| 3| 2| 4| 2| 2| 2| 3| 3| 3| 1| 4| 2| 3| 2| 3| 3| 9|             
                                           | 2| 0| 0| 6| 1| 9| 1| 5| 0| 9| 5| 9| 9| 9| 0| 0| 6| 8| 5| 9| 0| 9| 0| 0| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    37.5 PPM                               | 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3|             
                                           | 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7|             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM - cont                 |                                                                          |             
                                           |                                                                          |             
           Squamous                        |                                                                          |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lacrimal Gland                          |                                                             +            |             
                                            __________________________________________________________________________|             
   Zymbal's Gland                          |                                           +                              |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                 3                        |             
      Inflammation                         |                                                                          |             
      Nephropathy, Chronic                 | 4  3  2  3  2  2     4  3  2  1  1  3  3  2  2  3  4     4  2  2  3  2  2|             
      Pigmentation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Dilatation                           |                                                                          |             
      Inflammation                         |                                                                         3|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  72                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 5| 7| 7| 6| 7| 3| 6| 4| 7| 7| 7| 6| 7| 6| 7| 7| 6| 7| 7| 5| 4| 4| 4| 4|             
                             DAY ON TEST   | 0| 5| 0| 3| 8| 3| 5| 4| 3| 2| 2| 2| 5| 0| 7| 2| 3| 6| 2| 2| 6| 5| 5| 5| 5|             
                                           | 1| 5| 2| 0| 2| 0| 3| 6| 6| 9| 9| 0| 1| 0| 5| 9| 0| 3| 9| 9| 8| 6| 6| 6| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    37.5 PPM                               | 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6|             
                                           | 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Ectasia                              |                                           3                              |             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | A  +  A  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  +  A  +  +  +  +  A  A  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | A  +  +  +  +  +  A  +  +  +  +  +  A  A  A  +  +  +  +  +  A  +  +  +  +|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Basophilic Focus                     |                               1  3        1                    2         |             
      Basophilic Focus, Multiple           |          1     1                             1  2     1                  |             
      Clear Cell Focus                     |                                                                      1   |             
      Clear Cell Focus, Multiple           |                1              1                                          |             
      Congestion                           |                         2                                   2            |             
      Degeneration, Cystic                 | 2                                      2     1     2                    1|             
      Eosinophilic Focus                   |          1     2                                                         |             
      Eosinophilic Focus, Multiple         |                            2     2              2                        |             
      Fatty Change                         |                      3                 2                    2            |             
      Hemorrhage                           |                         1                                      1         |             
      Hepatodiaphragmatic Nodule           |                                                                          |             
      Inflammation                         |                                                                          |             
      Mixed Cell Focus                     |                                  2                    3                  |             
      Necrosis                             |                      1              4                                    |             
      Pigmentation                         |                                                                      2   |             
                                            __________________________________________________________________________|             
   Mesentery                               |                   A                                            +         |             
      Fat, Necrosis                        |                                                                3         |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation                         |                                                                          |             
      Acinar Cell, Atrophy                 | 2  2        1           2     1  1  1  2     2  1     2              1  2|             
      Duct, Ectasia                        |                                                                          |             
                                            __________________________________________________________________________|             
   Pharynx                                 |                                                                          |             
      Palate, Hyperplasia, Squamous        |                                                                          |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |             2                                      3                     |             
      Inflammation                         |                      1                             2                     |             
      Ulcer                                |       3                                                     2            |             
      Ulcer, Multiple                      |             2                                                            |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                                    2                     |             
      Inflammation                         |       2                                                                  |             
      Necrosis                             |       2              2                                                   |             
      Ulcer, Multiple                      |                      3                                                   |             
                                            __________________________________________________________________________|             
   Tongue                                  |                            +                                             |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  73                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 5| 7| 7| 6| 7| 3| 6| 4| 7| 7| 7| 6| 7| 6| 7| 7| 6| 7| 7| 5| 4| 4| 4| 4|             
                             DAY ON TEST   | 0| 5| 0| 3| 8| 3| 5| 4| 3| 2| 2| 2| 5| 0| 7| 2| 3| 6| 2| 2| 6| 5| 5| 5| 5|             
                                           | 1| 5| 2| 0| 2| 0| 3| 6| 6| 9| 9| 0| 1| 0| 5| 9| 0| 3| 9| 9| 8| 6| 6| 6| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    37.5 PPM                               | 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6|             
                                           | 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM - cont                  |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       | 2  2  2  1  1  1     2  1  2  1  2  2  2  2  2  2  1  1  2  1  1  1  1  1|             
      Inflammation                         |                      2           2                                       |             
      Atrium, Thrombosis                   |                      3                                                   |             
      Valve, Inflammation                  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Degeneration                         |                                                                          |             
      Hyperplasia                          |                                                                          |             
      Hypertrophy                          |                                              2                           |             
      Vacuolization Cytoplasmic            | 2     3     2                 2  1  1  3     1     2     1               |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |       2                    2        1                 1                  |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      |          +                                   +     +                     |             
      Hyperplasia                          |          3                                   2                           |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | M  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                                                          |             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                   4                                                      |             
      Pars Distalis, Angiectasis           |       3                             4                                   1|             
      Pars Distalis, Cyst                  |    1                          1                                          |             
      Pars Distalis, Hemorrhage            |                            2                                             |             
      Pars Distalis, Hyperplasia           |    1     2     2        2  2  2  3              2  2           2     1  2|             
      Pars Intermedia, Cyst                |          2                                                               |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  |                      2                                         1         |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Granuloma Sperm                      |             3                                                            |             
      Hypospermia                          | 4     4  2     4           3     4        4     4  4  4     2            |             
                                            __________________________________________________________________________|             
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Ectasia                              | 3  2  3  2  2  2  3  4  3  3  2  3  2  2  3  2  3  2  2  2  3  2     2  2|             
      Hyperplasia                          |          2                                                               |             
      Inflammation                         |                         2                             1              1   |             
                                            __________________________________________________________________________|             
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Concretion                           |    1                             1        2                             1|             
      Hyperplasia                          |          1           2                                                   |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  74                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 5| 7| 7| 6| 7| 3| 6| 4| 7| 7| 7| 6| 7| 6| 7| 7| 6| 7| 7| 5| 4| 4| 4| 4|             
                             DAY ON TEST   | 0| 5| 0| 3| 8| 3| 5| 4| 3| 2| 2| 2| 5| 0| 7| 2| 3| 6| 2| 2| 6| 5| 5| 5| 5|             
                                           | 1| 5| 2| 0| 2| 0| 3| 6| 6| 9| 9| 0| 1| 0| 5| 9| 0| 3| 9| 9| 8| 6| 6| 6| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    37.5 PPM                               | 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6|             
                                           | 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2|             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Inflammation                         | 3  2           2     2              3     2                 1  3        2|             
      Epithelium, Cytoplasmic Alteration   |                                                                          |             
                                            __________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Cellular                   | 4  3  3     1  4                 4     2        3  3  3     3            |             
      Ectasia                              |                                                                          |             
                                            __________________________________________________________________________|             
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              | 4           3        4     3                                             |             
      Degeneration                         |                                                                          |             
      Hypospermia                          |                                                             2            |             
      Arteriole, Inflammation              |                            3                             2               |             
      Bilateral, Atrophy                   |                                        3  4                              |             
      Bilateral, Degeneration              |                                                                          |             
      Interstitial Cell, Hyperplasia       | 2                       2  2  1                                2     2   |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |    3                 2  2     3  2                 3              1      |             
                                            __________________________________________________________________________|             
   Lymph Node, Bronchial                   | M  +  +  +  +  +  +  M  +  M  +  +  +  +  +  +  +  +  M  M  +  +  +  +  +|             
      Hemorrhage                           |       2  1                       3  3        1     3           1  3  1   |             
      Inflammation                         |                                                    2                     |             
      Pigmentation                         |          2                                                               |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                                          |             
      Hemorrhage                           |    1  3                                            2                     |             
      Hyperplasia, Lymphoid                |                         3                                                |             
      Hyperplasia, Plasma Cell             |                2              1  2        3  2                           |             
      Pigmentation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |       2                          1        2     2  1              1      |             
                                            __________________________________________________________________________|             
   Lymph Node, Mediastinal                 | M  +  +  +  M  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |    1  3  1     2  1  1     3  2        2     3  2  3  2     1  2  1  2  1|             
      Hyperplasia, Plasma Cell             |                               2                                          |             
      Pigmentation                         |                1     2        1                 2                        |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                               2                                          |             
      Fibrosis                             |                                                                          |             
      Hematopoietic Cell Proliferation     |                                     2              2                     |             
      Capsule, Fibrosis                    |                                                                          |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |    3  4  2     1     4  2  2  1     2  3  2  1  1  3     1  3  2  1     2|             
      Hemorrhage                           |                1  2              1  2        1                 1         |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  75                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 5| 7| 7| 6| 7| 3| 6| 4| 7| 7| 7| 6| 7| 6| 7| 7| 6| 7| 7| 5| 4| 4| 4| 4|             
                             DAY ON TEST   | 0| 5| 0| 3| 8| 3| 5| 4| 3| 2| 2| 2| 5| 0| 7| 2| 3| 6| 2| 2| 6| 5| 5| 5| 5|             
                                           | 1| 5| 2| 0| 2| 0| 3| 6| 6| 9| 9| 0| 1| 0| 5| 9| 0| 3| 9| 9| 8| 6| 6| 6| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    37.5 PPM                               | 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6|             
                                           | 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2|             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Galactocele                          |                                                             3            |             
      Lactation                            |       2     2        2     3  2     3  3  3  2           3               |             
      Pigmentation                         |                                                    2                     |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Pinna, Parakeratosis                 |                                                                          |             
      Subcutaneous Tissue, Abscess         |                               4                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Calvarium, Hemorrhage                |                   2                                                      |             
      Coccygeal, Fracture                  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Compression                          |             1                       2  3  2  1           3  2            |             
      Hemorrhage                           |                   3                                                      |             
      Hydrocephalus                        |                                                             2            |             
      Infiltration Cellular, Lymphocyte    |                                                                          |             
                                            __________________________________________________________________________|             
   Spinal Cord                             |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation                         |    1                                               1                     |             
      Epithelium, Hyperplasia              |    2                                                                     |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           | 2                 3                    2  3                              |             
      Hemorrhage                           | 1                                         2           2        1  1  2  2|             
      Infiltration Cellular, Histiocyte    |                                              2                           |             
      Inflammation                         |                1     1              4              3                     |             
      Leukocytosis                         |                                                                          |             
      Necrosis                             |                                                    2                     |             
      Alveolar Epithelium, Hyperplasia     |          2                                   1        1           1     2|             
      Artery, Thrombosis                   |                                                                          |             
      Goblet Cell, Hyperplasia             |                                                                          |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          | 2                                2  3                                    |             
      Foreign Body                         |                                     2              2                     |             
      Inflammation                         |    2           2                    3           2  2                     |             
      Goblet Cell, Hyperplasia             |                                                    2                    2|             
      Nasolacrimal Duct, Inflammation      |                            2                                             |             
      Olfactory Epithelium, Cytoplasmic    |                                                                          |             
          Alteration                       |    2                                                                     |             
      Respiratory Epithelium, Hyperplasia  |                                                                         1|             
      Respiratory Epithelium, Metaplasia,  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  76                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 5| 7| 7| 6| 7| 3| 6| 4| 7| 7| 7| 6| 7| 6| 7| 7| 6| 7| 7| 5| 4| 4| 4| 4|             
                             DAY ON TEST   | 0| 5| 0| 3| 8| 3| 5| 4| 3| 2| 2| 2| 5| 0| 7| 2| 3| 6| 2| 2| 6| 5| 5| 5| 5|             
                                           | 1| 5| 2| 0| 2| 0| 3| 6| 6| 9| 9| 0| 1| 0| 5| 9| 0| 3| 9| 9| 8| 6| 6| 6| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    37.5 PPM                               | 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6|             
                                           | 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2|             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM - cont                 |                                                                          |             
                                           |                                                                          |             
           Squamous                        |    2           2                                                         |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lacrimal Gland                          |                                                                          |             
                                            __________________________________________________________________________|             
   Zymbal's Gland                          |    +                    +                                                |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                                          |             
      Inflammation                         |                                                 2                        |             
      Nephropathy, Chronic                 | 4  1  2  2  2  2     2     3  2  2  2  3  2  2  2  2  2  3  2  1  1  2  2|             
      Pigmentation                         |       3                                            2                     |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Dilatation                           |                                        3                                 |             
      Inflammation                         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  77                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 6| 6| 6| 6| 6| 6|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1|                                                        |      A     |
    37.5 PPM                               | 6| 6| 6| 6| 6| 6|                                                        |      L     |
                                           | 3| 4| 5| 6| 7| 8|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM                         |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Esophagus                               | +  +  +  +  +  +                                                         |  56        |
      Ectasia                              |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  +                                                         |  55        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +                                                         |  54        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  +  +  +                                                         |  51        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  +  +                                                         |  54        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  +  +  +                                                         |  50        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  +  +  +  +                                                         |  46        |
                                            __________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +                                                         |  56        |
      Basophilic Focus                     | 1              1                                                         |     11  1.5|
      Basophilic Focus, Multiple           |          1                                                               |     11  1.4|
      Clear Cell Focus                     |                                                                          |      1  1.0|
      Clear Cell Focus, Multiple           |                                                                          |      9  1.1|
      Congestion                           |                                                                          |      2  2.0|
      Degeneration, Cystic                 |                                                                          |     12  1.5|
      Eosinophilic Focus                   |                                                                          |      7  1.4|
      Eosinophilic Focus, Multiple         |                                                                          |      4  2.0|
      Fatty Change                         |                                                                          |     12  1.8|
      Hemorrhage                           |             1                                                            |      3  1.0|
      Hepatodiaphragmatic Nodule           |    X                                                                     |      2  2.0|
      Inflammation                         |                                                                          |      1  1.0|
      Mixed Cell Focus                     |                                                                          |      4  2.0|
      Necrosis                             |                                                                          |      4  2.0|
      Pigmentation                         |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Mesentery                               |                                                                          |   1        |
      Fat, Necrosis                        |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +                                                         |  56        |
      Inflammation                         |                                                                          |      1  2.0|
      Acinar Cell, Atrophy                 |       2  2  1  2                                                         |     32  1.7|
      Duct, Ectasia                        |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Pharynx                                 |                                                                          |   1        |
      Palate, Hyperplasia, Squamous        |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +                                                         |  55        |
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +                                                         |  56        |
      Hyperplasia                          |                                                                          |      3  2.3|
      Inflammation                         |                                                                          |      4  1.5|
      Ulcer                                |                                                                          |      3  2.7|
      Ulcer, Multiple                      |                                                                          |      2  2.5|
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +                                                         |  56        |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  78                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 6| 6| 6| 6| 6| 6|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1|                                                        |      A     |
    37.5 PPM                               | 6| 6| 6| 6| 6| 6|                                                        |      L     |
                                           | 3| 4| 5| 6| 7| 8|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM - cont                  |                                                                          |            |
                                           |                                                                          |            |
      Hyperplasia                          |                                                                          |      1  2.0|
      Inflammation                         |                                                                          |      1  2.0|
      Necrosis                             |                                                                          |      3  2.0|
      Ulcer, Multiple                      |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Tongue                                  |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +                                                         |  56        |
      Cardiomyopathy                       | 1  1  1  1  1  2                                                         |     53  1.7|
      Inflammation                         |                                                                          |      2  2.0|
      Atrium, Thrombosis                   |                                                                          |      1  3.0|
      Valve, Inflammation                  |                                                                          |      1  3.0|
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +                                                         |  56        |
      Degeneration                         |                                                                          |      1  2.0|
      Hyperplasia                          |                1                                                         |      4  1.8|
      Hypertrophy                          |                                                                          |      3  1.7|
      Vacuolization Cytoplasmic            |                                                                          |     19  2.0|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +                                                         |  55        |
      Hyperplasia                          |                                                                          |     14  1.4|
                                            __________________________________________________________________________|____________|
   Islets, Pancreatic                      |                                                                          |   9        |
      Hyperplasia                          |                                                                          |      3  2.3|
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | +  +  +  +  +  +                                                         |  50        |
      Hyperplasia                          |                                                                          |      6  2.3|
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +                                                         |  56        |
      Hemorrhage                           |                                                                          |      1  4.0|
      Pars Distalis, Angiectasis           |                                                                          |      7  3.1|
      Pars Distalis, Cyst                  |                                                                          |      5  1.8|
      Pars Distalis, Hemorrhage            |                                                                          |      1  2.0|
      Pars Distalis, Hyperplasia           | 2  1        1  3                                                         |     22  2.0|
      Pars Intermedia, Cyst                |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +                                                         |  56        |
      C-Cell, Hyperplasia                  |          1                                                               |      5  1.6|
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  79                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 6| 6| 6| 6| 6| 6|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1|                                                        |      A     |
    37.5 PPM                               | 6| 6| 6| 6| 6| 6|                                                        |      L     |
                                           | 3| 4| 5| 6| 7| 8|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 GENITAL SYSTEM - cont                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Epididymis                              | +  +  +  +  +  +                                                         |  56        |
      Granuloma Sperm                      |                                                                          |      2  3.0|
      Hypospermia                          |                                                                          |     26  3.5|
                                            __________________________________________________________________________|____________|
   Preputial Gland                         | +  +  +  +  +  +                                                         |  56        |
      Ectasia                              | 2  2  1  2  3  2                                                         |     49  2.3|
      Hyperplasia                          |                                                                          |      1  2.0|
      Inflammation                         | 1  3  1                                                                  |      9  1.6|
                                            __________________________________________________________________________|____________|
   Prostate                                | +  +  +  +  +  +                                                         |  56        |
      Concretion                           |    1        1                                                            |      7  1.1|
      Hyperplasia                          |                                                                          |      4  1.8|
      Inflammation                         | 2  2  1  1  2  1                                                         |     24  2.1|
      Epithelium, Cytoplasmic Alteration   |                                                                          |      2  2.0|
                                            __________________________________________________________________________|____________|
   Seminal Vesicle                         | +  +  +  +  +  +                                                         |  56        |
      Depletion Cellular                   |                                                                          |     23  3.0|
      Ectasia                              |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Testes                                  | +  +  +  +  +  +                                                         |  56        |
      Atrophy                              |                                                                          |      6  3.2|
      Degeneration                         |                                                                          |      1  2.0|
      Hypospermia                          |                                                                          |      1  2.0|
      Arteriole, Inflammation              |                                                                          |      6  2.3|
      Bilateral, Atrophy                   |                                                                          |      2  3.5|
      Bilateral, Degeneration              |                                                                          |      1  2.0|
      Interstitial Cell, Hyperplasia       |    2                                                                     |     12  1.9|
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +                                                         |  55        |
      Hyperplasia                          |                                                                          |     15  2.5|
                                            __________________________________________________________________________|____________|
   Lymph Node, Bronchial                   | +  +  +  +  +  +                                                         |  43        |
      Hemorrhage                           |    1  1  1  1  1                                                         |     18  1.8|
      Inflammation                         |                                                                          |      1  2.0|
      Pigmentation                         |                                                                          |      3  1.7|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +                                                         |  55        |
      Cyst                                 |                                                                          |      1  3.0|
      Hemorrhage                           |                                                                          |      4  2.0|
      Hyperplasia, Lymphoid                |                                                                          |      1  3.0|
      Hyperplasia, Plasma Cell             |                                                                          |      7  2.3|
      Pigmentation                         |                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +                                                         |  56        |
      Hemorrhage                           |       1  1                                                               |     12  1.4|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  80                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 6| 6| 6| 6| 6| 6|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1|                                                        |      A     |
    37.5 PPM                               | 6| 6| 6| 6| 6| 6|                                                        |      L     |
                                           | 3| 4| 5| 6| 7| 8|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Lymph Node, Mediastinal                 | +  +  +  +  +  +                                                         |  52        |
      Hemorrhage                           | 1  3  2     2  1                                                         |     36  1.8|
      Hyperplasia, Plasma Cell             |                                                                          |      2  2.0|
      Pigmentation                         |                                                                          |     14  1.6|
                                            __________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +                                                         |  55        |
      Congestion                           |                                                                          |      2  2.0|
      Fibrosis                             |                                                                          |      1  2.0|
      Hematopoietic Cell Proliferation     |                                                                          |      6  2.3|
      Capsule, Fibrosis                    |                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Thymus                                  | +  +  +  +  +  +                                                         |  56        |
      Atrophy                              |       1  2     2                                                         |     43  2.1|
      Hemorrhage                           |                                                                          |      8  1.8|
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Mammary Gland                           | +  +  +  +  +  +                                                         |  53        |
      Galactocele                          |                                                                          |      2  3.0|
      Lactation                            |                                                                          |     18  2.4|
      Pigmentation                         |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +                                                         |  56        |
      Pinna, Parakeratosis                 |                                                                          |      1  3.0|
      Subcutaneous Tissue, Abscess         |                                                                          |      1  4.0|
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +                                                         |  56        |
      Calvarium, Hemorrhage                |                                                                          |      1  2.0|
      Coccygeal, Fracture                  |                                                                          |      1  3.0|
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +                                                         |  56        |
      Compression                          |                                                                          |     17  2.3|
      Hemorrhage                           |                                                                          |      2  2.0|
      Hydrocephalus                        |                                                                          |      3  2.3|
      Infiltration Cellular, Lymphocyte    |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Spinal Cord                             |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Larynx                                  | +  +  +  +  +  +                                                         |  56        |
      Inflammation                         |                                                                          |      2  1.0|
      Epithelium, Hyperplasia              |                                                                          |      1  2.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  81                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 6| 6| 6| 6| 6| 6|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1|                                                        |      A     |
    37.5 PPM                               | 6| 6| 6| 6| 6| 6|                                                        |      L     |
                                           | 3| 4| 5| 6| 7| 8|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 RESPIRATORY SYSTEM - cont                 |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +                                                         |  56        |
      Congestion                           |                                                                          |      5  2.4|
      Hemorrhage                           |       1     1  1                                                         |     15  1.3|
      Infiltration Cellular, Histiocyte    |                                                                          |      1  2.0|
      Inflammation                         |                                                                          |      8  1.9|
      Leukocytosis                         |                                                                          |      1  3.0|
      Necrosis                             |                                                                          |      1  2.0|
      Alveolar Epithelium, Hyperplasia     |    1                                                                     |     11  1.6|
      Artery, Thrombosis                   |                                                                          |      1  2.0|
      Goblet Cell, Hyperplasia             |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +                                                         |  55        |
      Angiectasis                          |                                                                          |      4  2.3|
      Foreign Body                         |                                                                          |      3  1.7|
      Inflammation                         |                                                                          |     10  2.0|
      Goblet Cell, Hyperplasia             |                3                                                         |      3  2.3|
      Nasolacrimal Duct, Inflammation      |                                                                          |      3  2.0|
      Olfactory Epithelium, Cytoplasmic    |                                                                          |            |
          Alteration                       |       1                                                                  |      3  1.7|
      Respiratory Epithelium, Hyperplasia  |                                                                          |      3  1.7|
      Respiratory Epithelium, Metaplasia,  |                                                                          |            |
           Squamous                        |                                                                          |      2  2.0|
                                            __________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +                                                         |  56        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Lacrimal Gland                          |                                                                          |   1        |
                                            __________________________________________________________________________|____________|
   Zymbal's Gland                          |                                                                          |   3        |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +                                                         |  55        |
      Cyst                                 |                                                                          |      1  3.0|
      Inflammation                         |                                                                          |      1  2.0|
      Nephropathy, Chronic                 | 2  1  1  2  2  2                                                         |     52  2.3|
      Pigmentation                         |                                                                          |      2  2.5|
                                            __________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  +  +  +                                                         |  55        |
      Dilatation                           |                                                                          |      1  3.0|
      Inflammation                         |                                                                          |      1  3.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  82                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 7| 7| 7| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 5| 7|             
                             DAY ON TEST   | 0| 3| 3| 3| 2| 3| 3| 2| 3| 3| 3| 3| 2| 3| 2| 2| 2| 2| 3| 2| 2| 3| 3| 4| 3|             
                                           | 6| 0| 0| 0| 9| 1| 0| 9| 0| 0| 0| 0| 9| 0| 9| 9| 9| 9| 0| 9| 9| 0| 0| 0| 0|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    75 PPM                                 | 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|             
                                           | 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Lymphoid                |                                                 2                        |             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Basophilic Focus                     |                                     1                                    |             
      Basophilic Focus, Multiple           |    2  1  2           2  1  1     1     1  2  1        3  2     1        2|             
      Clear Cell Focus                     |       1                                                                  |             
      Clear Cell Focus, Multiple           |          2  1              1     1        1                              |             
      Degeneration, Cystic                 |    1     2     2     2        2        2           2     2     2        2|             
      Eosinophilic Focus                   |    2              1                                2        1     2      |             
      Eosinophilic Focus, Multiple         |                      2     3  3        2     2                 1        3|             
      Fatty Change                         | 2                                            1                       4   |             
      Inflammation                         |                                                                      2   |             
      Mixed Cell Focus                     |                                                                   2      |             
      Mixed Cell Focus, Multiple           |                                  2        2                              |             
      Necrosis                             |                                                                      2   |             
      Bile Duct, Hyperplasia               |                               2                                          |             
                                            __________________________________________________________________________|             
   Mesentery                               |             +                                                     +      |             
      Fat, Necrosis                        |             3                                                     2      |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Ectopic Liver                        |                                                                         2|             
      Infiltration Cellular, Lymphocyte    |                                                                          |             
      Acinar Cell, Atrophy                 |             1  2  2  1     2  2  1     2  1     3        2  3  2  2     2|             
      Artery, Inflammation                 |                               4                             3            |             
      Duct, Ectasia                        |                                                                          |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    |                                  1                                       |             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          | 2              2                                      2              3   |             
      Inflammation                         |                3                                               2         |             
      Ulcer                                | 2                                                     2                  |             
      Ulcer, Multiple                      |                                                                      4   |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation                         |                                                                          |             
      Ulcer, Multiple                      |                                                                      3   |             
                                            __________________________________________________________________________|             
   Tongue                                  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  83                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 7| 7| 7| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 5| 7|             
                             DAY ON TEST   | 0| 3| 3| 3| 2| 3| 3| 2| 3| 3| 3| 3| 2| 3| 2| 2| 2| 2| 3| 2| 2| 3| 3| 4| 3|             
                                           | 6| 0| 0| 0| 9| 1| 0| 9| 0| 0| 0| 0| 9| 0| 9| 9| 9| 9| 0| 9| 9| 0| 0| 0| 0|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    75 PPM                                 | 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|             
                                           | 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9|             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM - cont              |                                                                          |             
                                           |                                                                          |             
      Cardiomyopathy                       | 2  2  2  1  1  3  2  1  2  1  2  1  1  1  2  2     3  1  1  2  2  2  1  2|             
      Atrium, Thrombosis                   |                                        3                                 |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Degeneration                         |                                                                          |             
      Hyperplasia                          |       2                 1           1                       2            |             
      Hypertrophy                          |             3           2                                                |             
      Vacuolization Cytoplasmic            |    2        2           2  2        2                       1  2     2  1|             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |    2     2  2  1     3     1  2  2     1  1        2  2  1  1        1   |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      |                                                    +           +         |             
      Hyperplasia                          |                                                                          |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  M  +  +  +  +  +  M  +  M  +  +  +  +  +  +  +  M  +  +  +  +|             
      Hyperplasia                          |                2                                   2                     |             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Pars Distalis, Angiectasis           |                                                                          |             
      Pars Distalis, Cyst                  |                      3                                2                  |             
      Pars Distalis, Hemorrhage            |                                                    2                     |             
      Pars Distalis, Hyperplasia           |       2  2     2  1  3                 3        2  1  3  2  3           3|             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  |          1                    2                             1        3   |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                                                                          |             
      Granuloma Sperm                      |                                                                         3|             
      Hypospermia                          |       4  4        2        4  4  2     4  4  4     4  2  3     2  3     4|             
      Inflammation                         |                         2                                               2|             
                                            __________________________________________________________________________|             
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Degeneration                         | 2                                                                        |             
      Ectasia                              |       3  2  3  3  2     1  2     2  1  3  2  3  1  2  3  2  2  3  2  2   |             
      Hyperplasia                          | 3                             3        4                                 |             
      Inflammation                         |    2                                                                     |             
                                            __________________________________________________________________________|             
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Concretion                           |                                                                      1   |             
      Congestion                           |                                                                          |             
      Hyperplasia                          |                               1        1     1                           |             
      Inflammation                         | 1           2  2  2                 1        2        2        3  2  3  1|             
                                            __________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  84                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 7| 7| 7| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 5| 7|             
                             DAY ON TEST   | 0| 3| 3| 3| 2| 3| 3| 2| 3| 3| 3| 3| 2| 3| 2| 2| 2| 2| 3| 2| 2| 3| 3| 4| 3|             
                                           | 6| 0| 0| 0| 9| 1| 0| 9| 0| 0| 0| 0| 9| 0| 9| 9| 9| 9| 0| 9| 9| 0| 0| 0| 0|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    75 PPM                                 | 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|             
                                           | 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9|             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Depletion Cellular                   | 2     4  3     3  2        4  4        4           2  2  3        4      |             
                                            __________________________________________________________________________|             
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |    2                 1     3           3                          3      |             
      Arteriole, Inflammation              |    2                 1     2           3                          2     2|             
      Bilateral, Atrophy                   |                                                                         4|             
      Interstitial Cell, Hyperplasia       |             1        1  2  1                    1                 3      |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                                                          |             
      Hyperplasia                          |                3                                         2               |             
                                            __________________________________________________________________________|             
   Lymph Node, Bronchial                   | +  +  M  M  +  +  +  +  M  +  +  +  M  +  +  M  M  +  M  +  +  +  +  M  +|             
      Hemorrhage                           | 3                 1                       1              1     3  1      |             
      Pigmentation                         |                   1  1                                                   |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |    3                                      2                              |             
      Hemorrhage                           |                      3                       2                           |             
      Hyperplasia, Plasma Cell             |                                           3                             2|             
      Infiltration Cellular, Histiocyte    |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                               2                             1        2   |             
                                            __________________________________________________________________________|             
   Lymph Node, Mediastinal                 | M  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +|             
      Hemorrhage                           |       2           2  2     2     1  1  1  2  2           2     3     1   |             
      Hyperplasia, Lymphoid                |                                                                         3|             
      Infiltration Cellular, Histiocyte    |                                                                          |             
      Pigmentation                         |    2  1           2  1     2        1     1  2                           |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Degeneration, Cystic                 |                                                                3         |             
      Fibrosis                             |       2                                      1                           |             
      Hematopoietic Cell Proliferation     |                3                                                     2   |             
      Hemorrhage                           |    2                                                                     |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              | 3     1  1  3  3  1  2  1     1     2  2  2  2     2  2     2  2     4  1|             
      Hemorrhage                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Lactation                            | 2                             2                       3        2     2   |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  85                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 7| 7| 7| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 5| 7|             
                             DAY ON TEST   | 0| 3| 3| 3| 2| 3| 3| 2| 3| 3| 3| 3| 2| 3| 2| 2| 2| 2| 3| 2| 2| 3| 3| 4| 3|             
                                           | 6| 0| 0| 0| 9| 1| 0| 9| 0| 0| 0| 0| 9| 0| 9| 9| 9| 9| 0| 9| 9| 0| 0| 0| 0|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    75 PPM                                 | 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|             
                                           | 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9|             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Compression                          | 3  3                                                                 2   |             
      Hemorrhage                           |                                                                          |             
      Hydrocephalus                        |                                                                          |             
      Necrosis                             |                2                                                         |             
                                            __________________________________________________________________________|             
   Spinal Cord                             | +                                                                        |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    |                               2                                          |             
      Inflammation                         | 1                                                                    2   |             
      Epithelium, Hyperplasia              |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Hemorrhage                           |                                                                      1   |             
      Inflammation                         |                                        2           2                     |             
      Alveolar Epithelium, Hyperplasia     | 2        1  2     1        2              1  2  4  2     1  2  2  1     2|             
      Arteriole, Inflammation              |                                        2                                 |             
      Artery, Inflammation                 |                                                                          |             
      Artery, Thrombosis                   |                                                                          |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Foreign Body                         |                         2  2                                             |             
      Hemorrhage                           |                                                                          |             
      Inflammation                         |                         2  2                                             |             
      Goblet Cell, Hyperplasia             |                                                                          |             
      Olfactory Epithelium, Cytoplasmic    |                                                                          |             
          Alteration                       |                                                                      1   |             
      Respiratory Epithelium, Hyperplasia  |                         2           1                                    |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Eye                                     |                                                                          |             
      Hemorrhage                           |                                                                          |             
      Inflammation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Zymbal's Gland                          |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Nephropathy, Chronic                 | 2  2  2  3  3  4  2  3  3  3  3  2  1  3  2  2  2  4  2  2  2  4  2  3  3|             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  86                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 7| 7| 7| 2| 5| 6| 7| 7| 7| 7| 7| 7| 7| 6| 7| 7| 7| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 2| 2| 2| 3| 2| 0| 5| 8| 3| 2| 1| 2| 3| 3| 3| 6| 1| 0| 2| 2| 3| 5| 5| 5| 5|             
                                           | 9| 9| 9| 0| 9| 0| 2| 4| 0| 9| 2| 9| 0| 0| 0| 7| 9| 3| 9| 9| 0| 6| 6| 6| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    75 PPM                                 | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7|             
                                           | 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  A  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  A  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  A  A  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Lymphoid                |                                                                          |             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Basophilic Focus                     |                                  1                 1                    1|             
      Basophilic Focus, Multiple           | 1  2  2  1  1           1           1  1  2              2               |             
      Clear Cell Focus                     |                         1        2                          1  1  2     1|             
      Clear Cell Focus, Multiple           |          1                             1                 1               |             
      Degeneration, Cystic                 | 1           1                    2  2                          1         |             
      Eosinophilic Focus                   |       2                                   2                 2            |             
      Eosinophilic Focus, Multiple         |             2           2              2                                 |             
      Fatty Change                         |    2                          3              3                           |             
      Inflammation                         |                                                                          |             
      Mixed Cell Focus                     |                                                 2                        |             
      Mixed Cell Focus, Multiple           |                                                                          |             
      Necrosis                             |                                                                   1      |             
      Bile Duct, Hyperplasia               | 2                                               2                        |             
                                            __________________________________________________________________________|             
   Mesentery                               |                         +                                                |             
      Fat, Necrosis                        |                         3                                                |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Ectopic Liver                        |                                                                          |             
      Infiltration Cellular, Lymphocyte    |                                                          2               |             
      Acinar Cell, Atrophy                 | 1  2  1  1  2     2  2  1  1     2  1  1     3  1           2           1|             
      Artery, Inflammation                 |                                                                          |             
      Duct, Ectasia                        |                                                                          |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                              3                           |             
      Inflammation                         |                                              4                           |             
      Ulcer                                |                                                                          |             
      Ulcer, Multiple                      |                                                 2                        |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation                         |                                              3                           |             
      Ulcer, Multiple                      |                                                                          |             
                                            __________________________________________________________________________|             
   Tongue                                  |                +                                                         |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  87                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 7| 7| 7| 2| 5| 6| 7| 7| 7| 7| 7| 7| 7| 6| 7| 7| 7| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 2| 2| 2| 3| 2| 0| 5| 8| 3| 2| 1| 2| 3| 3| 3| 6| 1| 0| 2| 2| 3| 5| 5| 5| 5|             
                                           | 9| 9| 9| 0| 9| 0| 2| 4| 0| 9| 2| 9| 0| 0| 0| 7| 9| 3| 9| 9| 0| 6| 6| 6| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    75 PPM                                 | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7|             
                                           | 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4|             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM - cont              |                                                                          |             
                                           |                                                                          |             
      Cardiomyopathy                       | 2  1  2  1  1  1  2  2  2  2  2  1  1  1  1  2  2  2  2  1  2  1  1  2  2|             
      Atrium, Thrombosis                   |                      2                                                   |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                          2               |             
      Degeneration                         |                      2                                                   |             
      Hyperplasia                          |    2                    2                                                |             
      Hypertrophy                          |                                                                          |             
      Vacuolization Cytoplasmic            | 1                          1  2        3     2  2                        |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          | 2                          2        3                    2               |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      |                                  +     +     +                           |             
      Hyperplasia                          |                                  2     2                                 |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  M  +  M  +  +  +  +  +  M  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                                          2               |             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Pars Distalis, Angiectasis           |                                        3        4     2     2            |             
      Pars Distalis, Cyst                  |                               3                                          |             
      Pars Distalis, Hemorrhage            |                                                                          |             
      Pars Distalis, Hyperplasia           |       2  3              2     3  1  3     2           3     2     2      |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  |                                           1                              |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                                                 2                        |             
      Granuloma Sperm                      |                                                                          |             
      Hypospermia                          |       3     3        4  4  2  4  3        4           2  3               |             
      Inflammation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Degeneration                         |                                                                          |             
      Ectasia                              | 1     2  2  3  2  2     1  2  2  2  1  2  2  3  2  3  2  2  2  3  2  1  2|             
      Hyperplasia                          |                                                                          |             
      Inflammation                         |    2                                   2                    2  2  1     2|             
                                            __________________________________________________________________________|             
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Concretion                           |                   1                                                  1  2|             
      Congestion                           |                                                                          |             
      Hyperplasia                          |                                  1        1              2               |             
      Inflammation                         | 2                 3           2     2              3           2  1  2  2|             
                                            __________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  88                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 7| 7| 7| 2| 5| 6| 7| 7| 7| 7| 7| 7| 7| 6| 7| 7| 7| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 2| 2| 2| 3| 2| 0| 5| 8| 3| 2| 1| 2| 3| 3| 3| 6| 1| 0| 2| 2| 3| 5| 5| 5| 5|             
                                           | 9| 9| 9| 0| 9| 0| 2| 4| 0| 9| 2| 9| 0| 0| 0| 7| 9| 3| 9| 9| 0| 6| 6| 6| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    75 PPM                                 | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7|             
                                           | 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4|             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Depletion Cellular                   |    3              2        2  4  3        2  3  4     2  2  2            |             
                                            __________________________________________________________________________|             
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                                     2                                    |             
      Arteriole, Inflammation              | 1                                   3           2  2                     |             
      Bilateral, Atrophy                   |                      4                       2  2                        |             
      Interstitial Cell, Hyperplasia       |                                                             1     2  1  1|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                                 3                        |             
      Hyperplasia                          |                1        3                                      1  1  1   |             
                                            __________________________________________________________________________|             
   Lymph Node, Bronchial                   | +  +  +  +  M  +  +  +  M  M  +  +  +  M  M  M  +  M  +  +  +  +  +  +  +|             
      Hemorrhage                           |          1     2              1                       2  2        1     1|             
      Pigmentation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                                          |             
      Hemorrhage                           |       1        2                                            1        1   |             
      Hyperplasia, Plasma Cell             | 2     2                 2     3                                          |             
      Infiltration Cellular, Histiocyte    |                      3                                                   |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                                 2                        |             
                                            __________________________________________________________________________|             
   Lymph Node, Mediastinal                 | +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           | 2  2  2     2  2        3  1                       2  2  2  1  2  1  1  2|             
      Hyperplasia, Lymphoid                |                                                                          |             
      Infiltration Cellular, Histiocyte    |                      3                                                   |             
      Pigmentation                         |                               1              1        2  1  1            |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Degeneration, Cystic                 |          1                                                               |             
      Fibrosis                             |                                                                          |             
      Hematopoietic Cell Proliferation     |                      3  1           1                                    |             
      Hemorrhage                           |                                                                          |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |    3     1  1     3  4  1  2  3        2  1  4  3  2  2  1  1  2     1  2|             
      Hemorrhage                           |                2                                                  1      |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Lactation                            |    2        2        2                       3  2                        |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  89                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 7| 7| 7| 2| 5| 6| 7| 7| 7| 7| 7| 7| 7| 6| 7| 7| 7| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 2| 2| 2| 3| 2| 0| 5| 8| 3| 2| 1| 2| 3| 3| 3| 6| 1| 0| 2| 2| 3| 5| 5| 5| 5|             
                                           | 9| 9| 9| 0| 9| 0| 2| 4| 0| 9| 2| 9| 0| 0| 0| 7| 9| 3| 9| 9| 0| 6| 6| 6| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    75 PPM                                 | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7|             
                                           | 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4|             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Compression                          |                                              3  2  3                     |             
      Hemorrhage                           |                               2                                          |             
      Hydrocephalus                        |                                                    2                     |             
      Necrosis                             |                                                                          |             
                                            __________________________________________________________________________|             
   Spinal Cord                             |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    |                                                                          |             
      Inflammation                         |                                                                          |             
      Epithelium, Hyperplasia              |                                                                   1      |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                3                                2  2                     |             
      Hemorrhage                           |                                                                   2     1|             
      Inflammation                         |                               1                                          |             
      Alveolar Epithelium, Hyperplasia     |    2  2     3           2        2  2  1     1  2  1     2  1     2     3|             
      Arteriole, Inflammation              |                                                                          |             
      Artery, Inflammation                 |                               2                                          |             
      Artery, Thrombosis                   |                               2                                          |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                     3                                    |             
      Foreign Body                         |                                                                          |             
      Hemorrhage                           |                3                                               2         |             
      Inflammation                         | 1        2                 1        2                                    |             
      Goblet Cell, Hyperplasia             |                                                                   2  1   |             
      Olfactory Epithelium, Cytoplasmic    |                                                                          |             
          Alteration                       |                            2                                             |             
      Respiratory Epithelium, Hyperplasia  |                                           1        2                     |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Eye                                     |                               +                                          |             
      Hemorrhage                           |                               3                                          |             
      Inflammation                         |                               3                                          |             
                                            __________________________________________________________________________|             
   Zymbal's Gland                          |                               +                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Nephropathy, Chronic                 | 3  2  2  2  2     2  2  3  2  2  2  3  1  2  3  4  2  3  2  1  1  1  1  1|             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  90                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 6| 6| 6| 6| 6| 6|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2|                                                        |      A     |
    75 PPM                                 | 7| 7| 7| 7| 7| 8|                                                        |      L     |
                                           | 5| 6| 7| 8| 9| 0|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM                         |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Esophagus                               | +  +  +  +  +  +                                                         |  56        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  +                                                         |  56        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +                                                         |  55        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  +  +  +                                                         |  54        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  +  +                                                         |  56        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  +  +  +                                                         |  54        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  +  +  +  +                                                         |  53        |
      Hyperplasia, Lymphoid                |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +                                                         |  56        |
      Basophilic Focus                     |    1     1                                                               |      6  1.0|
      Basophilic Focus, Multiple           |       1     1                                                            |     26  1.5|
      Clear Cell Focus                     |                1                                                         |      8  1.3|
      Clear Cell Focus, Multiple           |                                                                          |      8  1.1|
      Degeneration, Cystic                 |                                                                          |     15  1.7|
      Eosinophilic Focus                   |                                                                          |      8  1.8|
      Eosinophilic Focus, Multiple         |                                                                          |     10  2.2|
      Fatty Change                         |    1                                                                     |      7  2.3|
      Inflammation                         |                                                                          |      1  2.0|
      Mixed Cell Focus                     |                                                                          |      2  2.0|
      Mixed Cell Focus, Multiple           |                                                                          |      2  2.0|
      Necrosis                             |                                                                          |      2  1.5|
      Bile Duct, Hyperplasia               |                                                                          |      3  2.0|
                                            __________________________________________________________________________|____________|
   Mesentery                               |          +                                                               |   4        |
      Fat, Necrosis                        |          2                                                               |      4  2.5|
                                            __________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +                                                         |  56        |
      Ectopic Liver                        |                                                                          |      1  2.0|
      Infiltration Cellular, Lymphocyte    |                                                                          |      1  2.0|
      Acinar Cell, Atrophy                 | 1  1  2  1  1                                                            |     36  1.6|
      Artery, Inflammation                 |                                                                          |      2  3.5|
      Duct, Ectasia                        |                1                                                         |      1  1.0|
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +                                                         |  56        |
      Infiltration Cellular, Lymphocyte    |                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +                                                         |  56        |
      Hyperplasia                          |                                                                          |      5  2.4|
      Inflammation                         |                                                                          |      3  3.0|
      Ulcer                                |                                                                          |      2  2.0|
      Ulcer, Multiple                      |                                                                          |      2  3.0|
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +                                                         |  56        |
      Inflammation                         |                                                                          |      1  3.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  91                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 6| 6| 6| 6| 6| 6|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2|                                                        |      A     |
    75 PPM                                 | 7| 7| 7| 7| 7| 8|                                                        |      L     |
                                           | 5| 6| 7| 8| 9| 0|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM - cont                  |                                                                          |            |
                                           |                                                                          |            |
      Ulcer, Multiple                      |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Tongue                                  |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +                                                         |  56        |
      Cardiomyopathy                       | 2  1  1  1  1  1                                                         |     55  1.6|
      Atrium, Thrombosis                   |                                                                          |      2  2.5|
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +                                                         |  56        |
      Angiectasis                          |                                                                          |      1  2.0|
      Degeneration                         |                                                                          |      1  2.0|
      Hyperplasia                          |                                                                          |      6  1.7|
      Hypertrophy                          |                                                                          |      2  2.5|
      Vacuolization Cytoplasmic            |                                                                          |     15  1.8|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +                                                         |  56        |
      Hyperplasia                          |                                                                          |     19  1.7|
                                            __________________________________________________________________________|____________|
   Islets, Pancreatic                      |                                                                          |   5        |
      Hyperplasia                          |                                                                          |      2  2.0|
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | +  +  +  +  +  +                                                         |  48        |
      Hyperplasia                          |                                                                          |      3  2.0|
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +                                                         |  56        |
      Pars Distalis, Angiectasis           |                                                                          |      4  2.8|
      Pars Distalis, Cyst                  | 1                                                                        |      4  2.3|
      Pars Distalis, Hemorrhage            |                                                                          |      1  2.0|
      Pars Distalis, Hyperplasia           | 1  1  2                                                                  |     25  2.2|
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +                                                         |  56        |
      C-Cell, Hyperplasia                  |                                                                          |      5  1.6|
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Epididymis                              | +  +  +  +  +  +                                                         |  56        |
      Atrophy                              |                                                                          |      1  2.0|
      Granuloma Sperm                      |                                                                          |      1  3.0|
      Hypospermia                          |                                                                          |     25  3.3|
      Inflammation                         |                                                                          |      2  2.0|
                                            __________________________________________________________________________|____________|
   Preputial Gland                         | +  +  +  +  +  +                                                         |  56        |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  92                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 6| 6| 6| 6| 6| 6|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2|                                                        |      A     |
    75 PPM                                 | 7| 7| 7| 7| 7| 8|                                                        |      L     |
                                           | 5| 6| 7| 8| 9| 0|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 GENITAL SYSTEM - cont                     |                                                                          |            |
                                           |                                                                          |            |
      Degeneration                         |                                                                          |      1  2.0|
      Ectasia                              | 2  2  3  2  2  2                                                         |     49  2.1|
      Hyperplasia                          |                                                                          |      3  3.3|
      Inflammation                         | 1  2  2     2  2                                                         |     12  1.8|
                                            __________________________________________________________________________|____________|
   Prostate                                | +  +  +  +  +  +                                                         |  56        |
      Concretion                           |    1  1        1                                                         |      7  1.1|
      Congestion                           | 1                                                                        |      1  1.0|
      Hyperplasia                          |                                                                          |      6  1.2|
      Inflammation                         | 1  1           1                                                         |     23  1.9|
                                            __________________________________________________________________________|____________|
   Seminal Vesicle                         | +  +  +  +  +  +                                                         |  56        |
      Depletion Cellular                   |                                                                          |     23  2.9|
                                            __________________________________________________________________________|____________|
   Testes                                  | +  +  +  +  +  +                                                         |  56        |
      Atrophy                              |                                                                          |      6  2.3|
      Arteriole, Inflammation              |                                                                          |     10  2.0|
      Bilateral, Atrophy                   |                                                                          |      4  3.0|
      Interstitial Cell, Hyperplasia       |       1     1                                                            |     12  1.3|
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +                                                         |  56        |
      Hemorrhage                           |                                                                          |      1  3.0|
      Hyperplasia                          |             1                                                            |      8  1.6|
                                            __________________________________________________________________________|____________|
   Lymph Node, Bronchial                   | +  +  +  +  M  +                                                         |  40        |
      Hemorrhage                           | 1  1  2  1     1                                                         |     18  1.4|
      Pigmentation                         |                                                                          |      2  1.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +                                                         |  56        |
      Cyst                                 |                                                                          |      2  2.5|
      Hemorrhage                           |    1                                                                     |      7  1.6|
      Hyperplasia, Plasma Cell             |                                                                          |      6  2.3|
      Infiltration Cellular, Histiocyte    |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +                                                         |  56        |
      Hemorrhage                           |          1                                                               |      5  1.6|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mediastinal                 | +  +  +  +  +  +                                                         |  52        |
      Hemorrhage                           | 2  1  1  2  2  1                                                         |     33  1.7|
      Hyperplasia, Lymphoid                |                                                                          |      1  3.0|
      Infiltration Cellular, Histiocyte    |                                                                          |      1  3.0|
      Pigmentation                         |                                                                          |     13  1.4|
                                            __________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +                                                         |  56        |
      Degeneration, Cystic                 |                                                                          |      2  2.0|
      Fibrosis                             |                                                                          |      2  1.5|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  93                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 6| 6| 6| 6| 6| 6|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2|                                                        |      A     |
    75 PPM                                 | 7| 7| 7| 7| 7| 8|                                                        |      L     |
                                           | 5| 6| 7| 8| 9| 0|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |            |
                                           |                                                                          |            |
      Hematopoietic Cell Proliferation     |                                                                          |      5  2.0|
      Hemorrhage                           |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Thymus                                  | +  +  +  +  +  +                                                         |  55        |
      Atrophy                              | 2     1  1  1                                                            |     42  1.9|
      Hemorrhage                           |                                                                          |      2  1.5|
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Mammary Gland                           | +  +  +  +  +  +                                                         |  56        |
      Lactation                            |                                                                          |     10  2.2|
                                            __________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +                                                         |  56        |
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +                                                         |  56        |
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +                                                         |  56        |
      Compression                          |                                                                          |      6  2.7|
      Hemorrhage                           |                                                                          |      1  2.0|
      Hydrocephalus                        |                                                                          |      1  2.0|
      Necrosis                             |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Spinal Cord                             |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Larynx                                  | +  +  +  +  +  +                                                         |  56        |
      Infiltration Cellular, Lymphocyte    |                                                                          |      1  2.0|
      Inflammation                         | 1     2                                                                  |      4  1.5|
      Epithelium, Hyperplasia              |                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +                                                         |  56        |
      Congestion                           |                                                                          |      3  2.3|
      Hemorrhage                           | 1                                                                        |      4  1.3|
      Inflammation                         |                                                                          |      3  1.7|
      Alveolar Epithelium, Hyperplasia     |                                                                          |     28  1.8|
      Arteriole, Inflammation              |                                                                          |      1  2.0|
      Artery, Inflammation                 |                                                                          |      1  2.0|
      Artery, Thrombosis                   |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +                                                         |  56        |
      Angiectasis                          |                                                                          |      1  3.0|
      Foreign Body                         |             1                                                            |      3  1.7|
      Hemorrhage                           |                                                                          |      2  2.5|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  94                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 6| 6| 6| 6| 6| 6|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2|                                                        |      A     |
    75 PPM                                 | 7| 7| 7| 7| 7| 8|                                                        |      L     |
                                           | 5| 6| 7| 8| 9| 0|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 RESPIRATORY SYSTEM - cont                 |                                                                          |            |
                                           |                                                                          |            |
      Inflammation                         |             1                                                            |      7  1.6|
      Goblet Cell, Hyperplasia             | 1                                                                        |      3  1.3|
      Olfactory Epithelium, Cytoplasmic    |                                                                          |            |
          Alteration                       |                                                                          |      2  1.5|
      Respiratory Epithelium, Hyperplasia  |                                                                          |      4  1.5|
                                            __________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +                                                         |  56        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Eye                                     |                                                                          |   1        |
      Hemorrhage                           |                                                                          |      1  3.0|
      Inflammation                         |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Zymbal's Gland                          |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +                                                         |  56        |
      Nephropathy, Chronic                 | 1  1  2  1  1  2                                                         |     55  2.2|
                                            __________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  +  +  +                                                         |  56        |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  95                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 6| 6| 7| 5| 7| 7| 7| 7| 6| 7| 7| 7| 7| 7| 5| 6| 7| 7| 3| 7| 7| 7| 7| 7|             
                             DAY ON TEST   | 3| 0| 3| 3| 6| 3| 3| 3| 2| 1| 2| 2| 3| 2| 2| 8| 1| 2| 2| 3| 2| 2| 2| 2| 3|             
                                           | 0| 4| 6| 0| 4| 0| 0| 0| 2| 1| 9| 9| 0| 9| 9| 9| 0| 9| 1| 0| 9| 9| 9| 9| 0|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    150 PPM                                | 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6|             
                                           | 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lipocyte      |             3                                                            |             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation                         | 1                                                                        |             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation                         | 1                                                                        |             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Ectopic Tissue                       |                                                                          |             
      Hyperplasia                          |                                                                          |             
      Inflammation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  A  +  A  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Basophilic Focus                     |                            1  1                                          |             
      Basophilic Focus, Multiple           |       2  2     2                    2  2                    3     2     1|             
      Clear Cell Focus                     |          2                                                               |             
      Clear Cell Focus, Multiple           |                                        1                                 |             
      Congestion                           |             3                       2           3     2                  |             
      Degeneration, Cystic                 |                               1     1                                    |             
      Eosinophilic Focus                   |                                     2     1                              |             
      Eosinophilic Focus, Multiple         |                               2                    2                     |             
      Fatty Change                         | 3                       1  2                          1  1           4  2|             
      Infiltration Cellular, Lymphocyte    |                               1                                          |             
      Inflammation                         |                                                                          |             
      Mixed Cell Focus                     |                   3     2                                                |             
      Necrosis                             |                                                                          |             
                                            __________________________________________________________________________|             
   Mesentery                               |                         +                 +              +               |             
      Fat, Necrosis                        |                         2                                3               |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation                         |                                  1                                       |             
      Acinar Cell, Atrophy                 | 2  2     2  2     3  2  4  1        3  3  3  1              1  2        2|             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                                          4               |             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          | 2                                                        2               |             
      Inflammation                         |                                                                          |             
      Ulcer                                | 3                                            2                           |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation                         |                                                                          |             
      Ulcer                                | 2                                                        2               |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  96                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 6| 6| 7| 5| 7| 7| 7| 7| 6| 7| 7| 7| 7| 7| 5| 6| 7| 7| 3| 7| 7| 7| 7| 7|             
                             DAY ON TEST   | 3| 0| 3| 3| 6| 3| 3| 3| 2| 1| 2| 2| 3| 2| 2| 8| 1| 2| 2| 3| 2| 2| 2| 2| 3|             
                                           | 0| 4| 6| 0| 4| 0| 0| 0| 2| 1| 9| 9| 0| 9| 9| 9| 0| 9| 1| 0| 9| 9| 9| 9| 0|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    150 PPM                                | 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6|             
                                           | 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1|             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM - cont              |                                                                          |             
                                           |                                                                          |             
      Cardiomyopathy                       | 1  2  3  2  2  2  2  2  2     1  2  3  2  2  2  2  2        2  2  2  2  2|             
      Atrium, Dilatation                   |                         2                                                |             
      Atrium, Thrombosis                   |             4                                         3                  |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                         2                                                |             
      Cytoplasmic Alteration               |                                                                   2      |             
      Degeneration                         |    3                                         2                           |             
      Hyperplasia                          |                2                    2  2                                 |             
      Hypertrophy                          |                               2                                          |             
      Vacuolization Cytoplasmic            | 2              1     2        2        2     1        3  3  1        4   |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          | 2              2        2        1              1           2           1|             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      |                   +     +                                         +  +   |             
      Hyperplasia                          |                                                                      3   |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  +  +  +  M  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Pars Distalis, Angiectasis           |                                                                          |             
      Pars Distalis, Cyst                  |                                                             2            |             
      Pars Distalis, Hyperplasia           |          3        2                 3  2  2                 2     2      |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Tissue NOS                              |       +                                                                  |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Granuloma Sperm                      |                                                                3         |             
      Hypospermia                          | 3        4              2  4     4  4  2  4     4  4        3     4  3  4|             
                                            __________________________________________________________________________|             
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                     3                                    |             
      Ectasia                              | 2     3     2           1  2  2        2  2  2  3  3  2  3     1  2  1   |             
      Hyperplasia                          |                                                                          |             
      Inflammation                         |    2  3  2  1  1     2  2              2     2        2                  |             
                                            __________________________________________________________________________|             
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Concretion                           |          1                          2                    2        2      |             
      Hyperplasia                          |                2                 2                                      1|             
      Inflammation                         | 2              2     2  3     3     2  2  1        2           3  3      |             
      Vacuolization Cytoplasmic            |                                                                          |             
                                            __________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Cellular                   | 2  3  3  3  3     4        3     4  3  3  4     3  3  2  3        4  3   |             
      Ectasia                              |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  97                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 6| 6| 7| 5| 7| 7| 7| 7| 6| 7| 7| 7| 7| 7| 5| 6| 7| 7| 3| 7| 7| 7| 7| 7|             
                             DAY ON TEST   | 3| 0| 3| 3| 6| 3| 3| 3| 2| 1| 2| 2| 3| 2| 2| 8| 1| 2| 2| 3| 2| 2| 2| 2| 3|             
                                           | 0| 4| 6| 0| 4| 0| 0| 0| 2| 1| 9| 9| 0| 9| 9| 9| 0| 9| 1| 0| 9| 9| 9| 9| 0|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    150 PPM                                | 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6|             
                                           | 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1|             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Inflammation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              | 2     4                             3              4  2                  |             
      Hypospermia                          |                                                          3               |             
      Arteriole, Inflammation              |                                     2                                    |             
      Bilateral, Atrophy                   |                            4                                             |             
      Interstitial Cell, Hyperplasia       | 1  1        2  1           1                       1  1                  |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                         2                                                |             
      Hyperplasia                          |       4  2           1                    3           2  3               |             
      Pigmentation                         |                                              2                           |             
                                            __________________________________________________________________________|             
   Lymph Node                              |                                                          +               |             
      Deep Cervical, Inflammation          |                                                          2               |             
      Renal, Hemorrhage                    |                                                          2               |             
                                            __________________________________________________________________________|             
   Lymph Node, Bronchial                   | +  +  +  +  +  M  +  +  +  M  M  M  M  M  M  M  +  +  M  +  +  +  M  +  +|             
      Hemorrhage                           |    1     2  2           2                       2        2           1   |             
      Infiltration Cellular, Histiocyte    |                                                                          |             
      Pigmentation                         |    1     2                                                               |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                                 3                        |             
      Hyperplasia, Lymphoid                |                                                                          |             
      Hyperplasia, Plasma Cell             |                3  2                                                      |             
      Pigmentation                         |    2                                                                     |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           | 1           3                                   3     3  2              1|             
                                            __________________________________________________________________________|             
   Lymph Node, Mediastinal                 | +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Lymphoid                   |                                                       3                  |             
      Hemorrhage                           | 1        2  1           3        2     3  1  2  3  1  2     1  1     3  2|             
      Hyperplasia, Plasma Cell             |                                                                          |             
      Infiltration Cellular, Histiocyte    |                                                                          |             
      Pigmentation                         |                         2  2           2  2                 1  1     1  2|             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Degeneration, Cystic                 |                            1                                2        3   |             
      Developmental Malformation           |                                                                          |             
      Hematopoietic Cell Proliferation     | 2     3              2     3                          2  2           2   |             
      Inflammation                         |                                                                          |             
      Necrosis                             |                                                                          |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              | 3  3  3     2  2  1  2     2        2  2  1  3  1  1  2  4     1     3   |             
      Congestion                           |                         3                                                |             
      Cyst                                 | 2                                                                        |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  98                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 6| 6| 7| 5| 7| 7| 7| 7| 6| 7| 7| 7| 7| 7| 5| 6| 7| 7| 3| 7| 7| 7| 7| 7|             
                             DAY ON TEST   | 3| 0| 3| 3| 6| 3| 3| 3| 2| 1| 2| 2| 3| 2| 2| 8| 1| 2| 2| 3| 2| 2| 2| 2| 3|             
                                           | 0| 4| 6| 0| 4| 0| 0| 0| 2| 1| 9| 9| 0| 9| 9| 9| 0| 9| 1| 0| 9| 9| 9| 9| 0|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    150 PPM                                | 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6|             
                                           | 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Hemorrhage                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  +  +  M  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Galactocele                          |                                  3     3                       3         |             
      Hyperplasia                          |                                  2                                       |             
      Inflammation                         |                                                                          |             
      Lactation                            | 3  3           2     2              2        2                 3     4   |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Subcutaneous Tissue, Abscess         |                                                          3               |             
      Tail, Hyperkeratosis                 |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Compression                          | 3  1           3        2  2        1        2     2  2  2           2  2|             
      Hemorrhage                           |                            1                                             |             
      Hydrocephalus                        |                                              2                           |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Foreign Body                         |                                                                          |             
      Infiltration Cellular, Lymphocyte    |                      2                                                   |             
      Inflammation                         |                         2                                                |             
      Epithelium, Hyperplasia              |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |             2                                                            |             
      Hemorrhage                           |                                                                          |             
      Infiltration Cellular, Histiocyte    |                                                                          |             
      Inflammation                         |                                                                2         |             
      Alveolar Epithelium, Hyperplasia     | 1  2  2  3     2  1  1  2  2  2  2  2     3     2     3     3     1  2  1|             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                         3                                                |             
      Foreign Body                         |                                                                          |             
      Hemorrhage                           |                                                                          |             
      Infiltration Cellular, Lymphocyte    |                                                             2            |             
      Inflammation                         |       2                       2           1                       2     1|             
      Goblet Cell, Hyperplasia             |                                                                          |             
      Nasolacrimal Duct, Inflammation      |                                                          3     2         |             
      Olfactory Epithelium, Cytoplasmic    |                                                                          |             
          Alteration                       |                                                                          |             
      Respiratory Epithelium, Hyperplasia  |                               2                                         1|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  99                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 6| 6| 7| 5| 7| 7| 7| 7| 6| 7| 7| 7| 7| 7| 5| 6| 7| 7| 3| 7| 7| 7| 7| 7|             
                             DAY ON TEST   | 3| 0| 3| 3| 6| 3| 3| 3| 2| 1| 2| 2| 3| 2| 2| 8| 1| 2| 2| 3| 2| 2| 2| 2| 3|             
                                           | 0| 4| 6| 0| 4| 0| 0| 0| 2| 1| 9| 9| 0| 9| 9| 9| 0| 9| 1| 0| 9| 9| 9| 9| 0|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    150 PPM                                | 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6|             
                                           | 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1|             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM - cont                 |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Zymbal's Gland                          |                                                          +               |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                 2                        |             
      Cyst                                 |                                                                          |             
      Nephropathy, Chronic                 | 3  2  1  2  2  2  2  2  2  2  2  3  3  2  2  1  2  2  2     2  2  2  3  3|             
      Pigmentation                         |       2                    2              2                              |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Dilatation                           |                                                                3         |             
      Infiltration Cellular, Lymphocyte    |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page 100                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 5| 6| 6| 6| 7| 7| 7| 5| 7| 7| 7| 6| 7| 7| 6| 7| 7| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 1| 2| 2| 6| 9| 1| 3| 3| 2| 8| 3| 2| 3| 4| 2| 2| 4| 2| 3| 2| 3| 5| 5| 5| 5|             
                                           | 7| 9| 3| 7| 9| 1| 0| 0| 8| 2| 0| 9| 0| 0| 9| 9| 7| 9| 0| 9| 0| 6| 6| 6| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    150 PPM                                | 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8|             
                                           | 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lipocyte      |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  A  +  A  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|             
      Inflammation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Ectopic Tissue                       |                                                                          |             
      Hyperplasia                          |                            3                                             |             
      Inflammation                         |                            2                                             |             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | A  +  A  +  A  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  A  +  A  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Basophilic Focus                     |          1                                   1  2                        |             
      Basophilic Focus, Multiple           |    2              2  2  1           1  2           1  2     2        2  1|             
      Clear Cell Focus                     |                                                                          |             
      Clear Cell Focus, Multiple           |                                              2           2               |             
      Congestion                           |       1                       2                                          |             
      Degeneration, Cystic                 |    2                    2                                                |             
      Eosinophilic Focus                   |                                                                          |             
      Eosinophilic Focus, Multiple         |    2                                                     1               |             
      Fatty Change                         |       1                    3     2  2  3              1  2               |             
      Infiltration Cellular, Lymphocyte    |                                                                          |             
      Inflammation                         |                            3                                             |             
      Mixed Cell Focus                     |                      2              2                                    |             
      Necrosis                             | 3                          4                                             |             
                                            __________________________________________________________________________|             
   Mesentery                               |                   +        +     +                 +  +                  |             
      Fat, Necrosis                        |                            3     3                 2  3                  |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation                         |                            2                                             |             
      Acinar Cell, Atrophy                 | 1  2     1     3  3  2  2     2  2                 2           2  2      |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                        3                                 |             
      Inflammation                         |                                        3                                 |             
      Ulcer                                |                            4                                             |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation                         |                            2           1                                 |             
      Ulcer                                |                3                                                         |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page 101                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 5| 6| 6| 6| 7| 7| 7| 5| 7| 7| 7| 6| 7| 7| 6| 7| 7| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 1| 2| 2| 6| 9| 1| 3| 3| 2| 8| 3| 2| 3| 4| 2| 2| 4| 2| 3| 2| 3| 5| 5| 5| 5|             
                                           | 7| 9| 3| 7| 9| 1| 0| 0| 8| 2| 0| 9| 0| 0| 9| 9| 7| 9| 0| 9| 0| 6| 6| 6| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    150 PPM                                | 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8|             
                                           | 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6|             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM - cont              |                                                                          |             
                                           |                                                                          |             
      Cardiomyopathy                       | 2  3  1  1  2     3  2  1  1  1  3  2  2  2  3  3  2  2  2  2  1  2  2  2|             
      Atrium, Dilatation                   |                                                                          |             
      Atrium, Thrombosis                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Cytoplasmic Alteration               |                                                                          |             
      Degeneration                         |                                                                          |             
      Hyperplasia                          |                                                                          |             
      Hypertrophy                          |                      2                                                   |             
      Vacuolization Cytoplasmic            |    1     2                 3     3                 2     2               |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          | 2  4        1     2  1                                                   |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      |                                  +                                       |             
      Hyperplasia                          |                                                                          |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  M  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Pars Distalis, Angiectasis           |          2  3  4                          2                              |             
      Pars Distalis, Cyst                  |                                              4                       2   |             
      Pars Distalis, Hyperplasia           |    2     1                          3     2              3        3  2   |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  |                   1              3                          2            |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Tissue NOS                              |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Granuloma Sperm                      |                                                                          |             
      Hypospermia                          | 3  4     3  3     3  4  4  4        3  4  4  3     4     4  4            |             
                                            __________________________________________________________________________|             
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                                                          |             
      Ectasia                              | 3  2  2  2     2  2  3     3  2  2  2  2  3  2  3     2        3  2     2|             
      Hyperplasia                          |                                           3                              |             
      Inflammation                         |       1        2  1        2                                            1|             
                                            __________________________________________________________________________|             
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Concretion                           |       2                          2                                   1  1|             
      Hyperplasia                          |                               1                                          |             
      Inflammation                         |    2                             3  2  2  3  1  3              2  1      |             
      Vacuolization Cytoplasmic            |                                                          2               |             
                                            __________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Cellular                   | 4  2     3           3  4  3     2  1  3  2  3     2  3  4               |             
      Ectasia                              |             3                                                            |             
 _____________________________________________________________________________________________________________________|             
                                                             Page 102                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 5| 6| 6| 6| 7| 7| 7| 5| 7| 7| 7| 6| 7| 7| 6| 7| 7| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 1| 2| 2| 6| 9| 1| 3| 3| 2| 8| 3| 2| 3| 4| 2| 2| 4| 2| 3| 2| 3| 5| 5| 5| 5|             
                                           | 7| 9| 3| 7| 9| 1| 0| 0| 8| 2| 0| 9| 0| 0| 9| 9| 7| 9| 0| 9| 0| 6| 6| 6| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    150 PPM                                | 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8|             
                                           | 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6|             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Inflammation                         |                         2                       3                        |             
                                            __________________________________________________________________________|             
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |          3                          1                                    |             
      Hypospermia                          |                                                                          |             
      Arteriole, Inflammation              |                         3     3  1                 3                     |             
      Bilateral, Atrophy                   |                3        3  4     2     3           3                     |             
      Interstitial Cell, Hyperplasia       |       1  1                       2  2                 2              2   |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Hyperplasia                          | 2  2        3        2  2                                   2  1  2     1|             
      Pigmentation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node                              |                                                                          |             
      Deep Cervical, Inflammation          |                                                                          |             
      Renal, Hemorrhage                    |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Bronchial                   | +  +  +  +  +  +  M  +  +  M  M  M  +  +  M  +  +  M  +  +  M  +  +  +  +|             
      Hemorrhage                           | 3  4                 2                                   3        1  1  2|             
      Infiltration Cellular, Histiocyte    | 3                                                                        |             
      Pigmentation                         |       2                                                                  |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           | 3                    2                                                   |             
      Hyperplasia, Lymphoid                |                               2                                          |             
      Hyperplasia, Plasma Cell             |                         2     2                                          |             
      Pigmentation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  A     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           | 3                                                                        |             
                                            __________________________________________________________________________|             
   Lymph Node, Mediastinal                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Lymphoid                   |                                                                          |             
      Hemorrhage                           |       4              3  2  1  1     1     2  3  2     2  3     2  3  3  2|             
      Hyperplasia, Plasma Cell             |                         3  3                                             |             
      Infiltration Cellular, Histiocyte    | 2                                                                        |             
      Pigmentation                         | 2     3              2           2                                       |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                             3            |             
      Degeneration, Cystic                 |    3                                      2                              |             
      Developmental Malformation           |                                  1                                       |             
      Hematopoietic Cell Proliferation     | 2                 1     1  3     1                                1      |             
      Inflammation                         |                            4                                             |             
      Necrosis                             |                            3                                             |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              | 2  2     2  2  3        2  4  2  2     3  2     3  2  2        1  2  2  1|             
      Congestion                           |                                                 3                        |             
      Cyst                                 |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page 103                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 5| 6| 6| 6| 7| 7| 7| 5| 7| 7| 7| 6| 7| 7| 6| 7| 7| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 1| 2| 2| 6| 9| 1| 3| 3| 2| 8| 3| 2| 3| 4| 2| 2| 4| 2| 3| 2| 3| 5| 5| 5| 5|             
                                           | 7| 9| 3| 7| 9| 1| 0| 0| 8| 2| 0| 9| 0| 0| 9| 9| 7| 9| 0| 9| 0| 6| 6| 6| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    150 PPM                                | 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8|             
                                           | 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Hemorrhage                           |                                                 2                    1   |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +|             
      Galactocele                          |                                        3                                 |             
      Hyperplasia                          |                                                                          |             
      Inflammation                         |                                        2                                 |             
      Lactation                            |    1           1        2  3  3  3     3        3                        |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Subcutaneous Tissue, Abscess         |                                                                          |             
      Tail, Hyperkeratosis                 |                                  2                                       |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Compression                          |                3  3     2  1  2  1     3        3  2  3                  |             
      Hemorrhage                           |                                                                          |             
      Hydrocephalus                        |                                                       3                  |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Foreign Body                         |                         2                                                |             
      Infiltration Cellular, Lymphocyte    |             1                                                            |             
      Inflammation                         |                         1                                2               |             
      Epithelium, Hyperplasia              |                         2                                                |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |             2                                   2                        |             
      Hemorrhage                           |                                                                   1     1|             
      Infiltration Cellular, Histiocyte    | 2                                                                        |             
      Inflammation                         |       2                 3        2              1  2                     |             
      Alveolar Epithelium, Hyperplasia     | 2           2     1           2  2  2  2  2  3        2  3  2  2  2      |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          | 2                                                                        |             
      Foreign Body                         |                         3                                               2|             
      Hemorrhage                           |                                           2                              |             
      Infiltration Cellular, Lymphocyte    |    2                                                                     |             
      Inflammation                         |                         4  2           1           1                    2|             
      Goblet Cell, Hyperplasia             |                                                                      1   |             
      Nasolacrimal Duct, Inflammation      |                                                                          |             
      Olfactory Epithelium, Cytoplasmic    |                                                                          |             
          Alteration                       |    2                                      1                          1   |             
      Respiratory Epithelium, Hyperplasia  |                                        2                       2         |             
 _____________________________________________________________________________________________________________________|             
                                                             Page 104                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 5| 6| 6| 6| 7| 7| 7| 5| 7| 7| 7| 6| 7| 7| 6| 7| 7| 7| 7| 4| 4| 4| 4|             
                             DAY ON TEST   | 1| 2| 2| 6| 9| 1| 3| 3| 2| 8| 3| 2| 3| 4| 2| 2| 4| 2| 3| 2| 3| 5| 5| 5| 5|             
                                           | 7| 9| 3| 7| 9| 1| 0| 0| 8| 2| 0| 9| 0| 0| 9| 9| 7| 9| 0| 9| 0| 6| 6| 6| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    150 PPM                                | 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8|             
                                           | 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6|             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM - cont                 |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Zymbal's Gland                          |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Cyst                                 |          4                          2              4                     |             
      Nephropathy, Chronic                 | 2  3  2  2  1  1  2  3  2  3  3  3  2  3  2  2  2  3  2  2  2  1  1  1  1|             
      Pigmentation                         |          2                             2                                 |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Dilatation                           |                                                                          |             
      Infiltration Cellular, Lymphocyte    |                                                                      1   |             
 _____________________________________________________________________________________________________________________|             
                                                             Page 105                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 6| 6| 6| 6| 6| 6|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3|                                                        |      A     |
    150 PPM                                | 8| 8| 8| 9| 9| 9|                                                        |      L     |
                                           | 7| 8| 9| 0| 1| 2|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM                         |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Esophagus                               | +  +  +  +  +  +                                                         |  56        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  +                                                         |  55        |
      Infiltration Cellular, Lipocyte      |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +                                                         |  55        |
      Inflammation                         |                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  +  +  +                                                         |  53        |
      Inflammation                         |                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  +  +                                                         |  55        |
      Ectopic Tissue                       |                2                                                         |      1  2.0|
      Hyperplasia                          |                                                                          |      1  3.0|
      Inflammation                         |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  +  +  +                                                         |  49        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  +  +  +  +                                                         |  52        |
                                            __________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +                                                         |  56        |
      Basophilic Focus                     |       1  1                                                               |      7  1.1|
      Basophilic Focus, Multiple           | 1  1           1                                                         |     22  1.7|
      Clear Cell Focus                     |          1                                                               |      2  1.5|
      Clear Cell Focus, Multiple           |                                                                          |      3  1.7|
      Congestion                           |       2                                                                  |      7  2.1|
      Degeneration, Cystic                 |                                                                          |      4  1.5|
      Eosinophilic Focus                   |                                                                          |      2  1.5|
      Eosinophilic Focus, Multiple         |                                                                          |      4  1.8|
      Fatty Change                         |                                                                          |     14  2.0|
      Infiltration Cellular, Lymphocyte    |                                                                          |      1  1.0|
      Inflammation                         |                                                                          |      1  3.0|
      Mixed Cell Focus                     |                                                                          |      4  2.3|
      Necrosis                             |                                                                          |      2  3.5|
                                            __________________________________________________________________________|____________|
   Mesentery                               |    +     +                                                               |  10        |
      Fat, Necrosis                        |    3     2                                                               |      8  2.6|
                                            __________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +                                                         |  56        |
      Inflammation                         |                                                                          |      2  1.5|
      Acinar Cell, Atrophy                 | 3  2     2  2  2                                                         |     32  2.1|
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +                                                         |  56        |
      Abscess                              |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +                                                         |  56        |
      Hyperplasia                          |                                                                          |      3  2.3|
      Inflammation                         |                                                                          |      1  3.0|
      Ulcer                                |                                                                          |      3  3.0|
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +                                                         |  55        |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page 106                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 6| 6| 6| 6| 6| 6|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3|                                                        |      A     |
    150 PPM                                | 8| 8| 8| 9| 9| 9|                                                        |      L     |
                                           | 7| 8| 9| 0| 1| 2|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM - cont                  |                                                                          |            |
                                           |                                                                          |            |
      Inflammation                         |                                                                          |      2  1.5|
      Ulcer                                |                                                                          |      3  2.3|
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +                                                         |  56        |
      Cardiomyopathy                       |    2  1  1  1  2                                                         |     51  1.9|
      Atrium, Dilatation                   |                                                                          |      1  2.0|
      Atrium, Thrombosis                   |                                                                          |      2  3.5|
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +                                                         |  56        |
      Congestion                           |                                                                          |      1  2.0|
      Cytoplasmic Alteration               |                                                                          |      1  2.0|
      Degeneration                         |                                                                          |      2  2.5|
      Hyperplasia                          |                                                                          |      3  2.0|
      Hypertrophy                          |                                                                          |      2  2.0|
      Vacuolization Cytoplasmic            |                                                                          |     16  2.1|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +                                                         |  56        |
      Hyperplasia                          |                                                                          |     12  1.8|
                                            __________________________________________________________________________|____________|
   Islets, Pancreatic                      |                                                                          |   5        |
      Hyperplasia                          |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | +  +  +  +  +  +                                                         |  52        |
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +                                                         |  55        |
      Pars Distalis, Angiectasis           |                                                                          |      4  2.8|
      Pars Distalis, Cyst                  |                                                                          |      3  2.7|
      Pars Distalis, Hyperplasia           | 1     2     2  1                                                         |     18  2.1|
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +                                                         |  56        |
      C-Cell, Hyperplasia                  |                                                                          |      3  2.0|
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Tissue NOS                              |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Epididymis                              | +  +  +  +  +  +                                                         |  56        |
      Granuloma Sperm                      |                                                                          |      1  3.0|
      Hypospermia                          |                                                                          |     29  3.6|
                                            __________________________________________________________________________|____________|
   Preputial Gland                         | +  +  +  +  +  +                                                         |  56        |
      Abscess                              |                                                                          |      1  3.0|
      Ectasia                              | 2  2  2  2  3  2                                                         |     41  2.2|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page 107                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 6| 6| 6| 6| 6| 6|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3|                                                        |      A     |
    150 PPM                                | 8| 8| 8| 9| 9| 9|                                                        |      L     |
                                           | 7| 8| 9| 0| 1| 2|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 GENITAL SYSTEM - cont                     |                                                                          |            |
                                           |                                                                          |            |
      Hyperplasia                          |                                                                          |      1  3.0|
      Inflammation                         |                2                                                         |     16  1.8|
                                            __________________________________________________________________________|____________|
   Prostate                                | +  +  +  +  +  +                                                         |  56        |
      Concretion                           |       1     1                                                            |     10  1.5|
      Hyperplasia                          |                                                                          |      4  1.5|
      Inflammation                         | 2  2  2  2     2                                                         |     25  2.2|
      Vacuolization Cytoplasmic            |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Seminal Vesicle                         | +  +  +  +  +  +                                                         |  56        |
      Depletion Cellular                   |                                                                          |     31  3.0|
      Ectasia                              |                                                                          |      1  3.0|
      Inflammation                         |                                                                          |      2  2.5|
                                            __________________________________________________________________________|____________|
   Testes                                  | +  +  +  +  +  +                                                         |  56        |
      Atrophy                              |             3                                                            |      8  2.8|
      Hypospermia                          |                                                                          |      1  3.0|
      Arteriole, Inflammation              |                                                                          |      5  2.4|
      Bilateral, Atrophy                   |                                                                          |      7  3.1|
      Interstitial Cell, Hyperplasia       |          1                                                               |     14  1.4|
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +                                                         |  56        |
      Congestion                           |                                                                          |      1  2.0|
      Hyperplasia                          |                                                                          |     15  2.1|
      Pigmentation                         |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Lymph Node                              |                                                                          |   1        |
      Deep Cervical, Inflammation          |                                                                          |      1  2.0|
      Renal, Hemorrhage                    |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Bronchial                   | +  +  +  +  +  +                                                         |  39        |
      Hemorrhage                           |    2  1  2     3                                                         |     18  2.0|
      Infiltration Cellular, Histiocyte    |                                                                          |      1  3.0|
      Pigmentation                         |                                                                          |      3  1.7|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +                                                         |  56        |
      Hemorrhage                           |                                                                          |      3  2.7|
      Hyperplasia, Lymphoid                |                                                                          |      1  2.0|
      Hyperplasia, Plasma Cell             |                                                                          |      4  2.3|
      Pigmentation                         |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +                                                         |  54        |
      Hemorrhage                           |                                                                          |      7  2.3|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mediastinal                 | +  +  +  +  +  +                                                         |  55        |
      Depletion Lymphoid                   |                                                                          |      1  3.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page 108                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 6| 6| 6| 6| 6| 6|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3|                                                        |      A     |
    150 PPM                                | 8| 8| 8| 9| 9| 9|                                                        |      L     |
                                           | 7| 8| 9| 0| 1| 2|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |            |
                                           |                                                                          |            |
      Hemorrhage                           | 2  3  1  1  2  3                                                         |     36  2.1|
      Hyperplasia, Plasma Cell             |                                                                          |      2  3.0|
      Infiltration Cellular, Histiocyte    |                                                                          |      1  2.0|
      Pigmentation                         |                                                                          |     12  1.8|
                                            __________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +                                                         |  55        |
      Congestion                           |                                                                          |      1  3.0|
      Degeneration, Cystic                 |                                                                          |      5  2.2|
      Developmental Malformation           |                                                                          |      1  1.0|
      Hematopoietic Cell Proliferation     |                                                                          |     13  1.9|
      Inflammation                         |                                                                          |      1  4.0|
      Necrosis                             |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Thymus                                  | +  +  +  +  +  +                                                         |  54        |
      Atrophy                              | 1  1  1  1     1                                                         |     41  2.0|
      Congestion                           |                                                                          |      2  3.0|
      Cyst                                 |                                                                          |      1  2.0|
      Hemorrhage                           |       1                                                                  |      3  1.3|
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Mammary Gland                           | +  +  +  +  +  +                                                         |  53        |
      Galactocele                          |                                                                          |      4  3.0|
      Hyperplasia                          |                                                                          |      1  2.0|
      Inflammation                         |                                                                          |      1  2.0|
      Lactation                            |                                                                          |     16  2.5|
                                            __________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +                                                         |  56        |
      Subcutaneous Tissue, Abscess         |                                                                          |      1  3.0|
      Tail, Hyperkeratosis                 |                                                                          |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +                                                         |  56        |
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +                                                         |  56        |
      Compression                          |                                                                          |     22  2.1|
      Hemorrhage                           |                                                                          |      1  1.0|
      Hydrocephalus                        |                                                                          |      2  2.5|
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Larynx                                  | +  +  +  +  +  +                                                         |  56        |
      Foreign Body                         |                                                                          |      1  2.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page 109                                                               
NTP Experiment-Test: 05185-03                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                          ISOBUTYL NITRITE                                     Date: 04/18/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:24:48  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 4| 4| 4| 4| 4|                                                        |            |
                             DAY ON TEST   | 5| 5| 5| 5| 5| 5|                                                        |            |
                                           | 6| 6| 6| 6| 6| 6|                                                        |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0|                                                        |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0|                                                        |      T     |
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3|                                                        |      A     |
    150 PPM                                | 8| 8| 8| 9| 9| 9|                                                        |      L     |
                                           | 7| 8| 9| 0| 1| 2|                                                        |            |
 __________________________________________________________________________________________________________________________________ 
 RESPIRATORY SYSTEM - cont                 |                                                                          |            |
                                           |                                                                          |            |
      Infiltration Cellular, Lymphocyte    |                                                                          |      2  1.5|
      Inflammation                         |       1                                                                  |      4  1.5|
      Epithelium, Hyperplasia              |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +                                                         |  56        |
      Congestion                           |                                                                          |      3  2.0|
      Hemorrhage                           | 1                                                                        |      3  1.0|
      Infiltration Cellular, Histiocyte    |                                                                          |      1  2.0|
      Inflammation                         |                                                                          |      6  2.0|
      Alveolar Epithelium, Hyperplasia     | 2  1  1     1  2                                                         |     38  1.9|
                                            __________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +                                                         |  56        |
      Angiectasis                          |                                                                          |      2  2.5|
      Foreign Body                         |                                                                          |      2  2.5|
      Hemorrhage                           |                                                                          |      1  2.0|
      Infiltration Cellular, Lymphocyte    |                                                                          |      2  2.0|
      Inflammation                         |          1                                                               |     11  1.7|
      Goblet Cell, Hyperplasia             |                                                                          |      1  1.0|
      Nasolacrimal Duct, Inflammation      |                                                                          |      2  2.5|
      Olfactory Epithelium, Cytoplasmic    |                                                                          |            |
          Alteration                       | 1  1                                                                     |      5  1.2|
      Respiratory Epithelium, Hyperplasia  |                                                                          |      4  1.8|
                                            __________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +                                                         |  56        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Zymbal's Gland                          |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +                                                         |  56        |
      Congestion                           |                                                                          |      1  2.0|
      Cyst                                 |                                                                          |      3  3.3|
      Nephropathy, Chronic                 | 1  1  1  1  1  1                                                         |     55  2.0|
      Pigmentation                         |                                                                          |      5  2.0|
                                            __________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  +  +  +                                                         |  55        |
      Dilatation                           |                                                                          |      1  3.0|
      Infiltration Cellular, Lymphocyte    |                                                                          |      1  1.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
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