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TDMS Study 88070-03 Pathology Tables

NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24




       Facility:  Battelle Northwest

       Chemical CAS #:  115-11-0007

       Lock Date:  10/05/95

       Cage Range:  All

       Reasons For Removal:    All

       Removal Date Range:     All

       Treatment Groups:       Include All




































Note:  Animals arranged according to CID number

                                                              Page   1


NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 7| 7| 5| 7| 6| 6| 7| 4| 4| 4| 7| 7| 5| 5| 5| 7| 7| 7| 7| 4| 7| 4| 7|             
                             DAY ON TEST   | 3| 3| 3| 2| 7| 1| 6| 4| 3| 8| 9| 4| 3| 3| 8| 5| 2| 3| 0| 3| 3| 2| 3| 8| 3|             
                                           | 3| 3| 3| 0| 3| 4| 3| 2| 3| 8| 6| 0| 3| 4| 1| 2| 9| 4| 5| 4| 4| 1| 4| 8| 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   | 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|             
    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                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |          X                                                               |             
                                           |__________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Polyp Adenomatous                    |                               X                                          |             
                                           |__________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +|             
                                           |__________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +|             
      Leukemia Mononuclear                 |          X  X                                                            |             
                                           |__________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X        X  X  X  X  X                 X           X     X  X  X         |             
                                           |__________________________________________________________________________|             
   Mesentery                               |    +        +                 +                 +           +            |             
                                           |__________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |          X                                                               |             
                                           |__________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |__________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |          X  X  X  X  X                                   X     X         |             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page   2                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 7| 7| 5| 7| 6| 6| 7| 4| 4| 4| 7| 7| 5| 5| 5| 7| 7| 7| 7| 4| 7| 4| 7|             
                             DAY ON TEST   | 3| 3| 3| 2| 7| 1| 6| 4| 3| 8| 9| 4| 3| 3| 8| 5| 2| 3| 0| 3| 3| 2| 3| 8| 3|             
                                           | 3| 3| 3| 0| 3| 4| 3| 2| 3| 8| 6| 0| 3| 4| 1| 2| 9| 4| 5| 4| 4| 1| 4| 8| 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   | 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|             
    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|             
 __________________________________________|__________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |__________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Adenoma                              |                                                             X            |             
      Leukemia Mononuclear                 | X        X  X  X  X  X                 X                 X     X         |             
                                           |__________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X        X  X  X  X  X                 X                 X     X         |             
      Pheochromocytoma Complex             |                                                                          |             
      Pheochromocytoma Benign              |                         X                                X               |             
                                           |__________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Adenoma                              |                                                                          |             
                                           |__________________________________________________________________________|             
   Parathyroid Gland                       | +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |          X  X  X  X  X                 X                 X     X         |             
      Pars Distalis, Adenoma               | X  X  X  X  X  X     X  X     X     X  X  X     X  X  X  X  X     X     X|             
                                           |__________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Adenoma                      |    X                                                        X            |             
      C-Cell, Carcinoma                    |                                                                          |             
      Follicular Cell, Carcinoma           |                                                    X                     |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |__________________________________________________________________________|             
   Clitoral Gland                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Adenoma                              | X                                                                        |             
      Bilateral, Carcinoma                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |          X  X  X                                               X         |             
                                           |__________________________________________________________________________|             
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page   3                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 7| 7| 5| 7| 6| 6| 7| 4| 4| 4| 7| 7| 5| 5| 5| 7| 7| 7| 7| 4| 7| 4| 7|             
                             DAY ON TEST   | 3| 3| 3| 2| 7| 1| 6| 4| 3| 8| 9| 4| 3| 3| 8| 5| 2| 3| 0| 3| 3| 2| 3| 8| 3|             
                                           | 3| 3| 3| 0| 3| 4| 3| 2| 3| 8| 6| 0| 3| 4| 1| 2| 9| 4| 5| 4| 4| 1| 4| 8| 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   | 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|             
    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                     |                                                                          |             
                                           |                                                                          |             
      Leukemia Mononuclear                 |          X                                                               |             
      Polyp Stromal                        |             X        X                          X                        |             
      Polyp Stromal, Multiple              |                                                                          |             
                                           |__________________________________________________________________________|             
   Vagina                                  |          +                                                               |             
      Polyp                                |          X                                                               |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |__________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X        X  X  X  X  X                                   X     X         |             
                                           |__________________________________________________________________________|             
   Lymph Node                              |          +  +     +              +                                       |             
      Pancreatic, Leukemia Mononuclear     |          X  X     X                                                      |             
      Renal, Leukemia Mononuclear          |                                                                          |             
      Renal, Sarcoma                       |                                  X                                       |             
                                           |__________________________________________________________________________|             
   Lymph Node, Bronchial                   | +  M  +  +  M  +  +  +  +  M  +  M  +  +  +  M  M  +  +  M  +  M  +  M  +|             
      Leukemia Mononuclear                 | X        X     X  X  X                 X                                 |             
                                           |__________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  M  +  M  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X        X  X  X  X  X                 X                 X     X         |             
                                           |__________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X        X  X  X  X  X                 X                 X     X         |             
                                           |__________________________________________________________________________|             
   Lymph Node, Mediastinal                 | M  +  +  +  M  +  +  +  +  +  M  +  +  +  +  +  +  +  M  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |          X     X  X  X                                   X     X         |             
      Plasma Cell Tumor Malignant          |                                                                          |             
                                           |__________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X        X  X  X  X  X                 X           X     X  X  X         |             
                                           |__________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |          X  X  X     X                                         X         |             
 _____________________________________________________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page   4                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 7| 7| 5| 7| 6| 6| 7| 4| 4| 4| 7| 7| 5| 5| 5| 7| 7| 7| 7| 4| 7| 4| 7|             
                             DAY ON TEST   | 3| 3| 3| 2| 7| 1| 6| 4| 3| 8| 9| 4| 3| 3| 8| 5| 2| 3| 0| 3| 3| 2| 3| 8| 3|             
                                           | 3| 3| 3| 0| 3| 4| 3| 2| 3| 8| 6| 0| 3| 4| 1| 2| 9| 4| 5| 4| 4| 1| 4| 8| 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   | 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|             
    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                      |                                                                          |             
                                           |__________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Adenoma                              |    X                                                                     |             
      Carcinoma                            |                                                                      X   |             
      Fibroadenoma                         | X                                   X                 X  X        X      |             
      Fibroadenoma, Multiple               |    X                    X                 X                 X            |             
                                           |__________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Keratoacanthoma                      |                                        X                                 |             
      Subcutaneous Tissue, Fibroma         |                                                                          |             
      Subcutaneous Tissue, Fibrous         |                                                                          |             
          Histiocytoma                     |                            X                                             |             
      Subcutaneous Tissue, Hemangioma      |                                                                   X      |             
      Subcutaneous Tissue, Sarcoma         |                                     X                                    |             
      Subcutaneous Tissue, Pinna, Melanoma |                                                                          |             
          Malignant                        |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |__________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Osteosarcoma                         | X                                                                        |             
      Sarcoma                              |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |__________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |             X                                                  X         |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |__________________________________________________________________________|             
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Alveolar/Bronchiolar Adenoma         |    X                                                              X      |             
      Carcinoma, Metastatic, Mammary Gland |                                                                      X   |             
      Leukemia Mononuclear                 | X        X  X  X  X  X                 X           X     X  X  X         |             
      Plasma Cell Tumor Malignant,         |                                                                          |             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page   5                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 7| 7| 5| 7| 6| 6| 7| 4| 4| 4| 7| 7| 5| 5| 5| 7| 7| 7| 7| 4| 7| 4| 7|             
                             DAY ON TEST   | 3| 3| 3| 2| 7| 1| 6| 4| 3| 8| 9| 4| 3| 3| 8| 5| 2| 3| 0| 3| 3| 2| 3| 8| 3|             
                                           | 3| 3| 3| 0| 3| 4| 3| 2| 3| 8| 6| 0| 3| 4| 1| 2| 9| 4| 5| 4| 4| 1| 4| 8| 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   | 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|             
    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|             
 __________________________________________|__________________________________________________________________________|             
 RESPIRATORY SYSTEM - cont                 |                                                                          |             
                                           |                                                                          |             
          Metastatic, Lymph Node,          |                                                                          |             
          Mediastinal                      |                                                                          |             
      Mediastinum, Plasma Cell Tumor       |                                                                          |             
          Malignant, Metastatic, Lymph     |                                                                          |             
          Node, Mediastinal                |                                                                          |             
                                           |__________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |             X                                                            |             
                                           |__________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |__________________________________________________________________________|             
   Eye                                     |             +                    +           +                           |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |__________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X        X  X  X  X  X                 X                 X  X  X         |             
      Renal Tubule, Carcinoma              |                                              X                           |             
                                           |__________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |             X                                            X               |             
 __________________________________________|__________________________________________________________________________|             
 SYSTEMIC LESIONS                          |                                                                          |             
                                            __________________________________________________________________________|             
   Multiple Organs                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X        X  X  X  X  X                 X           X     X  X  X         |             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page   6                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 6| 7| 6| 7| 7| 7| 7| 7| 7| 7| 7| 6| 6| 7| 7| 7| 7| 3| 7| 5| 7| 6| 7| 7| 6|            |
                             DAY ON TEST   | 9| 3| 4| 1| 3| 2| 2| 3| 3| 3| 3| 6| 7| 3| 3| 3| 2| 9| 3| 5| 0| 0| 3| 3| 4|            |
                                           | 1| 4| 2| 5| 4| 2| 6| 4| 4| 4| 4| 4| 8| 5| 5| 5| 0| 0| 5| 2| 5| 8| 5| 5| 8|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    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|     L      |
                                           | 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                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |                                                                          |          1 |
                                           |__________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  A  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  I  +|  47        |
      Polyp Adenomatous                    |                                                                          |          1 |
                                           |__________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  A  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
                                           |__________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                           |__________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  A  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  47        |
                                           |__________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  A  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +|  46        |
      Leukemia Mononuclear                 |                                                                          |          2 |
                                           |__________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |    X           X  X                                      X     X  X     X|         18 |
                                           |__________________________________________________________________________|____________|
   Mesentery                               |          +                       +              +                        |   8        |
                                           |__________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                                          X     X        X|          4 |
                                           |__________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                                                X         |          1 |
                                           |__________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|            |
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page   7                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 6| 7| 6| 7| 7| 7| 7| 7| 7| 7| 7| 6| 6| 7| 7| 7| 7| 3| 7| 5| 7| 6| 7| 7| 6|            |
                             DAY ON TEST   | 9| 3| 4| 1| 3| 2| 2| 3| 3| 3| 3| 6| 7| 3| 3| 3| 2| 9| 3| 5| 0| 0| 3| 3| 4|            |
                                           | 1| 4| 2| 5| 4| 2| 6| 4| 4| 4| 4| 4| 8| 5| 5| 5| 0| 0| 5| 2| 5| 8| 5| 5| 8|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    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|     L      |
                                           | 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                     |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |    X                                                     X     X        X|         11 |
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Adenoma                              |                                                                          |          1 |
      Leukemia Mononuclear                 |    X           X  X                                      X     X        X|         15 |
                                           |__________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |    X           X  X                                      X     X        X|         15 |
      Pheochromocytoma Complex             |                         X                                                |          1 |
      Pheochromocytoma Benign              |             X                                                            |          3 |
                                           |__________________________________________________________________________|____________|
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Adenoma                              |                   X                                                      |          1 |
                                           |__________________________________________________________________________|____________|
   Parathyroid Gland                       | +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
                                           |__________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |    X              X                                      X     X        X|         13 |
      Pars Distalis, Adenoma               | X     X  X  X  X  X  X  X  X  X  X  X  X  X     X     X     X  X  X  X   |         39 |
                                           |__________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      C-Cell, Adenoma                      |                      X  X                 X           X              X   |          7 |
      C-Cell, Carcinoma                    |                X                                X                        |          2 |
      Follicular Cell, Carcinoma           |                                                                          |          1 |
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page   8                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 6| 7| 6| 7| 7| 7| 7| 7| 7| 7| 7| 6| 6| 7| 7| 7| 7| 3| 7| 5| 7| 6| 7| 7| 6|            |
                             DAY ON TEST   | 9| 3| 4| 1| 3| 2| 2| 3| 3| 3| 3| 6| 7| 3| 3| 3| 2| 9| 3| 5| 0| 0| 3| 3| 4|            |
                                           | 1| 4| 2| 5| 4| 2| 6| 4| 4| 4| 4| 4| 8| 5| 5| 5| 0| 0| 5| 2| 5| 8| 5| 5| 8|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    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|     L      |
                                           | 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                     |                                                                          |            |
                                           |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Clitoral Gland                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Adenoma                              |                               X                                      X   |          3 |
      Bilateral, Carcinoma                 |                                  X                                       |          1 |
                                           |__________________________________________________________________________|____________|
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |    X              X                                            X        X|          8 |
                                           |__________________________________________________________________________|____________|
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                                                         X|          2 |
      Polyp Stromal                        |                   X                             X        X              X|          7 |
      Polyp Stromal, Multiple              |                         X                                                |          1 |
                                           |__________________________________________________________________________|____________|
   Vagina                                  |                                                                          |   1        |
      Polyp                                |                                                                          |          1 |
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |    X              X                                      X     X        X|         13 |
                                           |__________________________________________________________________________|____________|
   Lymph Node                              |                                                          +     +         |   6        |
      Pancreatic, Leukemia Mononuclear     |                                                                X         |          4 |
      Renal, Leukemia Mononuclear          |                                                          X     X         |          2 |
      Renal, Sarcoma                       |                                                                          |          1 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Bronchial                   | +  +  +  +  +  +  M  +  M  +  M  +  +  +  +  +  +  M  +  M  +  +  +  +  +|  36        |
      Leukemia Mononuclear                 |    X           X                                               X        X|         10 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  M  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +|  44        |
      Leukemia Mononuclear                 |    X           X  X                                      X     X        X|         15 |
                                           |__________________________________________________________________________|____________|
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page   9                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 6| 7| 6| 7| 7| 7| 7| 7| 7| 7| 7| 6| 6| 7| 7| 7| 7| 3| 7| 5| 7| 6| 7| 7| 6|            |
                             DAY ON TEST   | 9| 3| 4| 1| 3| 2| 2| 3| 3| 3| 3| 6| 7| 3| 3| 3| 2| 9| 3| 5| 0| 0| 3| 3| 4|            |
                                           | 1| 4| 2| 5| 4| 2| 6| 4| 4| 4| 4| 4| 8| 5| 5| 5| 0| 0| 5| 2| 5| 8| 5| 5| 8|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    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|     L      |
                                           | 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               |                                                                          |            |
                                           |                                                                          |            |
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |    X           X  X                                      X     X        X|         15 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Mediastinal                 | +  +  +  +  +  +  +  +  +  +  +  +  +  M  M  +  M  +  +  +  +  +  M  +  +|  42        |
      Leukemia Mononuclear                 |    X           X  X                                      X     X        X|         12 |
      Plasma Cell Tumor Malignant          |                                                    X                     |          1 |
                                           |__________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |    X           X  X                                      X     X  X     X|         18 |
                                           |__________________________________________________________________________|____________|
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +|  48        |
      Leukemia Mononuclear                 |    X                                                           X        X|          8 |
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Adenoma                              |                                                                          |          1 |
      Carcinoma                            |                                                                      X   |          2 |
      Fibroadenoma                         | X     X     X        X  X        X  X     X  X              X        X   |         16 |
      Fibroadenoma, Multiple               |                            X                    X                        |          6 |
                                           |__________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Keratoacanthoma                      |                                                                          |          1 |
      Subcutaneous Tissue, Fibroma         |                         X                                                |          1 |
      Subcutaneous Tissue, Fibrous         |                                                                          |            |
          Histiocytoma                     |                                                                          |          1 |
      Subcutaneous Tissue, Hemangioma      |                                                                          |          1 |
      Subcutaneous Tissue, Sarcoma         |                                                                          |          1 |
      Subcutaneous Tissue, Pinna, Melanoma |                                                                          |            |
          Malignant                        |                                           X                              |          1 |
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  10                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 6| 7| 6| 7| 7| 7| 7| 7| 7| 7| 7| 6| 6| 7| 7| 7| 7| 3| 7| 5| 7| 6| 7| 7| 6|            |
                             DAY ON TEST   | 9| 3| 4| 1| 3| 2| 2| 3| 3| 3| 3| 6| 7| 3| 3| 3| 2| 9| 3| 5| 0| 0| 3| 3| 4|            |
                                           | 1| 4| 2| 5| 4| 2| 6| 4| 4| 4| 4| 4| 8| 5| 5| 5| 0| 0| 5| 2| 5| 8| 5| 5| 8|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    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|     L      |
                                           | 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|            |
 _____________________________________________________________________________________________________________________|____________|
 MUSCULOSKELETAL SYSTEM - cont             |                                                                          |            |
                                           |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Osteosarcoma                         |                                                                          |          1 |
      Sarcoma                              |                                        X                                 |          1 |
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                                                          |          2 |
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Alveolar/Bronchiolar Adenoma         |                                                                          |          2 |
      Carcinoma, Metastatic, Mammary Gland |                                                                          |          1 |
      Leukemia Mononuclear                 |    X           X  X                                      X     X  X     X|         18 |
      Plasma Cell Tumor Malignant,         |                                                                          |            |
          Metastatic, Lymph Node,          |                                                                          |            |
          Mediastinal                      |                                                    X                     |          1 |
      Mediastinum, Plasma Cell Tumor       |                                                                          |            |
          Malignant, Metastatic, Lymph     |                                                                          |            |
          Node, Mediastinal                |                                                    X                     |          1 |
                                           |__________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                                                          |          1 |
                                           |__________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |__________________________________________________________________________|____________|
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  11                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 6| 7| 6| 7| 7| 7| 7| 7| 7| 7| 7| 6| 6| 7| 7| 7| 7| 3| 7| 5| 7| 6| 7| 7| 6|            |
                             DAY ON TEST   | 9| 3| 4| 1| 3| 2| 2| 3| 3| 3| 3| 6| 7| 3| 3| 3| 2| 9| 3| 5| 0| 0| 3| 3| 4|            |
                                           | 1| 4| 2| 5| 4| 2| 6| 4| 4| 4| 4| 4| 8| 5| 5| 5| 0| 0| 5| 2| 5| 8| 5| 5| 8|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    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|     L      |
                                           | 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              |                                                                          |            |
                                           |                                                                          |            |
   Eye                                     |                                                                         +|   4        |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |    X           X  X                                      X     X  X     X|         17 |
      Renal Tubule, Carcinoma              |                                                                          |          1 |
                                           |__________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |    X                                                     X     X         |          5 |
 __________________________________________________________________________________________________________________________________ 
 SYSTEMIC LESIONS                          |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Multiple Organs                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |    X           X  X                                      X     X  X     X|         18 |
 __________________________________________________________________________________________________________________________________ 
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  12                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 5| 7| 7| 0| 7| 7| 7| 6| 7| 4| 7| 6| 7| 7| 5| 6| 4| 6| 7| 6| 6| 6| 7| 7|             
                             DAY ON TEST   | 9| 4| 2| 0| 1| 3| 3| 1| 6| 3| 4| 3| 0| 3| 3| 6| 0| 9| 8| 3| 9| 8| 6| 3| 3|             
                                           | 6| 8| 2| 8| 3| 3| 3| 9| 2| 3| 0| 3| 8| 4| 4| 5| 3| 4| 8| 4| 2| 8| 4| 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 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|             
    500 PPM                                | 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                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                              X                           |             
                                           |__________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  I  I  +  +  I  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                         X                    X                           |             
                                           |__________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Carcinoma, Metastatic, Thyroid Gland |                                                             X            |             
      Leukemia Mononuclear                 | X     X        X  X     X           X     X  X        X  X     X         |             
                                           |__________________________________________________________________________|             
   Mesentery                               |       +           +  +  +     +        +                       +         |             
                                           |__________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                         X           X     X  X                           |             
                                           |__________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Tongue                                  |                                                                      +   |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |__________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  13                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 5| 7| 7| 0| 7| 7| 7| 6| 7| 4| 7| 6| 7| 7| 5| 6| 4| 6| 7| 6| 6| 6| 7| 7|             
                             DAY ON TEST   | 9| 4| 2| 0| 1| 3| 3| 1| 6| 3| 4| 3| 0| 3| 3| 6| 0| 9| 8| 3| 9| 8| 6| 3| 3|             
                                           | 6| 8| 2| 8| 3| 3| 3| 9| 2| 3| 0| 3| 8| 4| 4| 5| 3| 4| 8| 4| 2| 8| 4| 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 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|             
    500 PPM                                | 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              |                                                                          |             
                                           |                                                                          |             
      Leukemia Mononuclear                 | X                       X           X     X  X                 X         |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |__________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Adenoma                              |                                           X                              |             
      Leukemia Mononuclear                 | X     X                 X           X     X  X        X  X     X         |             
                                           |__________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X     X                 X           X     X  X        X  X     X         |             
      Pheochromocytoma Benign              |       X                                                                  |             
                                           |__________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X                       X           X     X  X           X     X         |             
      Pars Distalis, Adenoma               | X  X  X        X  X  X     X     X     X        X  X  X        X  X  X   |             
                                           |__________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Adenoma                      |                X  X                    X                                 |             
      C-Cell, Carcinoma                    |                                                 X           X            |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |__________________________________________________________________________|             
   Clitoral Gland                          | +  +  +  +  +  +  +  +  +  +  +  +  +  I  +  +  +  +  +  +  +  +  +  +  +|             
      Adenoma                              |                   X                                                      |             
                                           |__________________________________________________________________________|             
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X                       X           X     X  X           X               |             
                                           |__________________________________________________________________________|             
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  14                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 5| 7| 7| 0| 7| 7| 7| 6| 7| 4| 7| 6| 7| 7| 5| 6| 4| 6| 7| 6| 6| 6| 7| 7|             
                             DAY ON TEST   | 9| 4| 2| 0| 1| 3| 3| 1| 6| 3| 4| 3| 0| 3| 3| 6| 0| 9| 8| 3| 9| 8| 6| 3| 3|             
                                           | 6| 8| 2| 8| 3| 3| 3| 9| 2| 3| 0| 3| 8| 4| 4| 5| 3| 4| 8| 4| 2| 8| 4| 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 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|             
    500 PPM                                | 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                     |                                                                          |             
                                           |                                                                          |             
      Leukemia Mononuclear                 |                                              X                           |             
      Polyp Stromal                        |                         X        X                          X            |             
                                           |__________________________________________________________________________|             
   Vagina                                  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |__________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X                                   X     X  X           X     X         |             
                                           |__________________________________________________________________________|             
   Lymph Node                              |                                           +  +                           |             
      Leukemia Mononuclear                 |                                           X  X                           |             
      Iliac, Leukemia Mononuclear          |                                           X  X                           |             
      Pancreatic, Leukemia Mononuclear     |                                              X                           |             
      Renal, Leukemia Mononuclear          |                                           X  X                           |             
                                           |__________________________________________________________________________|             
   Lymph Node, Bronchial                   | +  M  +  +  M  +  +  +  +  +  M  M  M  M  +  +  M  +  +  M  M  M  M  +  M|             
      Leukemia Mononuclear                 | X     X        X  X     X                 X  X        X                  |             
                                           |__________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  M  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  M  +|             
      Leukemia Mononuclear                 | X     X        X  X     X           X     X  X        X  X     X         |             
                                           |__________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X     X        X  X     X           X     X  X        X  X     X         |             
                                           |__________________________________________________________________________|             
   Lymph Node, Mediastinal                 | +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  M  +|             
      Leukemia Mononuclear                 | X     X        X  X     X           X     X  X        X  X     X         |             
                                           |__________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X     X        X  X     X           X     X  X        X  X     X         |             
                                           |__________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X     X        X        X                 X  X        X        X         |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |__________________________________________________________________________|             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  15                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 5| 7| 7| 0| 7| 7| 7| 6| 7| 4| 7| 6| 7| 7| 5| 6| 4| 6| 7| 6| 6| 6| 7| 7|             
                             DAY ON TEST   | 9| 4| 2| 0| 1| 3| 3| 1| 6| 3| 4| 3| 0| 3| 3| 6| 0| 9| 8| 3| 9| 8| 6| 3| 3|             
                                           | 6| 8| 2| 8| 3| 3| 3| 9| 2| 3| 0| 3| 8| 4| 4| 5| 3| 4| 8| 4| 2| 8| 4| 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 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|             
    500 PPM                                | 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                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Adenoma                              |                                                          X               |             
      Carcinoma                            |                            X                                             |             
      Fibroadenoma                         | X        X     X  X  X  X     X     X                          X         |             
      Fibroadenoma, Multiple               |                                  X                                   X   |             
                                           |__________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Subcutaneous Tissue, Fibrosarcoma    |                            X                                             |             
      Subcutaneous Tissue, Sarcoma         |    X     X                                                               |             
      Subcutaneous Tissue, Schwannoma      |                                                                          |             
          Malignant                        |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |__________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |__________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X                                   X                                    |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |__________________________________________________________________________|             
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Adenoma                              |                                                                          |             
      Fibrosarcoma, Metastatic, Skin       |                            X                                             |             
      Leukemia Mononuclear                 | X     X        X  X     X           X     X  X        X  X     X         |             
                                           |__________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |__________________________________________________________________________|             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  16                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 5| 7| 7| 0| 7| 7| 7| 6| 7| 4| 7| 6| 7| 7| 5| 6| 4| 6| 7| 6| 6| 6| 7| 7|             
                             DAY ON TEST   | 9| 4| 2| 0| 1| 3| 3| 1| 6| 3| 4| 3| 0| 3| 3| 6| 0| 9| 8| 3| 9| 8| 6| 3| 3|             
                                           | 6| 8| 2| 8| 3| 3| 3| 9| 2| 3| 0| 3| 8| 4| 4| 5| 3| 4| 8| 4| 2| 8| 4| 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 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|             
    500 PPM                                | 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              |                                                                          |             
                                           |                                                                          |             
   Ear                                     |                         +                                                |             
                                           |__________________________________________________________________________|             
   Eye                                     |                +              +                 +                        |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |__________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X              X        X           X     X  X        X  X     X         |             
      Stromal Nephroma                     |                                                       X                  |             
                                           |__________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +|             
      Leukemia Mononuclear                 |                         X                 X  X                           |             
 __________________________________________|__________________________________________________________________________|             
 SYSTEMIC LESIONS                          |                                                                          |             
                                            __________________________________________________________________________|             
   Multiple Organs                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X     X        X  X     X           X     X  X        X  X     X         |             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  17                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 7| 7| 5| 7| 7| 7| 5| 7| 6| 5| 7| 7| 7| 6| 6| 2| 7| 7| 4| 4| 7| 4| 7| 7|            |
                             DAY ON TEST   | 3| 1| 3| 8| 3| 3| 1| 7| 3| 3| 3| 0| 1| 3| 2| 3| 1| 3| 3| 2| 7| 3| 5| 3| 3|            |
                                           | 4| 6| 4| 0| 4| 4| 8| 3| 4| 0| 4| 1| 4| 4| 1| 5| 6| 4| 5| 0| 9| 5| 5| 5| 5|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    500 PPM                                | 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|     L      |
                                           | 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                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                                                          |          1 |
                                           |__________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  47        |
                                           |__________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                           |__________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  47        |
                                           |__________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  47        |
      Leukemia Mononuclear                 |                                                                          |          2 |
                                           |__________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Carcinoma, Metastatic, Thyroid Gland |                                                                          |          1 |
      Leukemia Mononuclear                 |       X                                      X     X     X     X         |         16 |
                                           |__________________________________________________________________________|____________|
   Mesentery                               |                   +     +           +                                    |  10        |
                                           |__________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |       X                                            X                     |          6 |
                                           |__________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Tongue                                  |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  18                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 7| 7| 5| 7| 7| 7| 5| 7| 6| 5| 7| 7| 7| 6| 6| 2| 7| 7| 4| 4| 7| 4| 7| 7|            |
                             DAY ON TEST   | 3| 1| 3| 8| 3| 3| 1| 7| 3| 3| 3| 0| 1| 3| 2| 3| 1| 3| 3| 2| 7| 3| 5| 3| 3|            |
                                           | 4| 6| 4| 0| 4| 4| 8| 3| 4| 0| 4| 1| 4| 4| 1| 5| 6| 4| 5| 0| 9| 5| 5| 5| 5|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    500 PPM                                | 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|     L      |
                                           | 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                     |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                              X           X               |          8 |
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Adenoma                              |                                                                          |          1 |
      Leukemia Mononuclear                 |       X                                      X     X     X               |         13 |
                                           |__________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |       X                                      X     X     X               |         13 |
      Pheochromocytoma Benign              |                X                                                        X|          3 |
                                           |__________________________________________________________________________|____________|
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +|  48        |
                                           |__________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +|  49        |
      Leukemia Mononuclear                 |                                              X     X     X               |         10 |
      Pars Distalis, Adenoma               |    X  X  X  X  X  X     X  X  X  X  X  X  X  X        X     X     X     X|         33 |
                                           |__________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      C-Cell, Adenoma                      |       X        X                       X                                 |          6 |
      C-Cell, Carcinoma                    |                            X                                             |          3 |
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Clitoral Gland                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Adenoma                              |             X  X                                                         |          3 |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  19                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 7| 7| 5| 7| 7| 7| 5| 7| 6| 5| 7| 7| 7| 6| 6| 2| 7| 7| 4| 4| 7| 4| 7| 7|            |
                             DAY ON TEST   | 3| 1| 3| 8| 3| 3| 1| 7| 3| 3| 3| 0| 1| 3| 2| 3| 1| 3| 3| 2| 7| 3| 5| 3| 3|            |
                                           | 4| 6| 4| 0| 4| 4| 8| 3| 4| 0| 4| 1| 4| 4| 1| 5| 6| 4| 5| 0| 9| 5| 5| 5| 5|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    500 PPM                                | 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|     L      |
                                           | 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                     |                                                                          |            |
                                           |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                                          X               |          7 |
                                           |__________________________________________________________________________|____________|
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                                                          |          1 |
      Polyp Stromal                        |                      X  X                          X  X  X  X            |          9 |
                                           |__________________________________________________________________________|____________|
   Vagina                                  |                                                          +               |   1        |
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                              X     X     X               |          9 |
                                           |__________________________________________________________________________|____________|
   Lymph Node                              |                                                       +                  |   3        |
      Leukemia Mononuclear                 |                                                                          |          2 |
      Iliac, Leukemia Mononuclear          |                                                                          |          2 |
      Pancreatic, Leukemia Mononuclear     |                                                                          |          1 |
      Renal, Leukemia Mononuclear          |                                                                          |          2 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Bronchial                   | +  +  +  +  +  +  +  +  +  +  M  +  M  +  M  M  M  +  +  M  +  +  M  +  +|  31        |
      Leukemia Mononuclear                 |       X                                            X           X         |         11 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +|  46        |
      Leukemia Mononuclear                 |       X                                      X     X     X               |         15 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |       X                                      X     X     X               |         15 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Mediastinal                 | +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  M  +  +  +  +|  45        |
      Leukemia Mononuclear                 |       X                                      X     X     X     X         |         16 |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  20                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 7| 7| 5| 7| 7| 7| 5| 7| 6| 5| 7| 7| 7| 6| 6| 2| 7| 7| 4| 4| 7| 4| 7| 7|            |
                             DAY ON TEST   | 3| 1| 3| 8| 3| 3| 1| 7| 3| 3| 3| 0| 1| 3| 2| 3| 1| 3| 3| 2| 7| 3| 5| 3| 3|            |
                                           | 4| 6| 4| 0| 4| 4| 8| 3| 4| 0| 4| 1| 4| 4| 1| 5| 6| 4| 5| 0| 9| 5| 5| 5| 5|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    500 PPM                                | 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|     L      |
                                           | 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               |                                                                          |            |
                                           |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |       X                                      X     X     X     X         |         16 |
                                           |__________________________________________________________________________|____________|
   Thymus                                  | +  +  +  M  +  +  +  +  +  +  +  +  +  +  M  +  +  M  +  +  +  +  +  +  +|  47        |
      Leukemia Mononuclear                 |                                              X                           |          9 |
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Adenoma                              |                                                                          |          1 |
      Carcinoma                            |                                                                      X   |          2 |
      Fibroadenoma                         | X           X        X     X     X                                       |         14 |
      Fibroadenoma, Multiple               |                                                    X  X              X   |          5 |
                                           |__________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Subcutaneous Tissue, Fibrosarcoma    |                                                                          |          1 |
      Subcutaneous Tissue, Sarcoma         |                                                                          |          2 |
      Subcutaneous Tissue, Schwannoma      |                                                                          |            |
          Malignant                        |                                                 X                        |          1 |
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                                          X               |          3 |
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |__________________________________________________________________________|____________|
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  21                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 7| 7| 5| 7| 7| 7| 5| 7| 6| 5| 7| 7| 7| 6| 6| 2| 7| 7| 4| 4| 7| 4| 7| 7|            |
                             DAY ON TEST   | 3| 1| 3| 8| 3| 3| 1| 7| 3| 3| 3| 0| 1| 3| 2| 3| 1| 3| 3| 2| 7| 3| 5| 3| 3|            |
                                           | 4| 6| 4| 0| 4| 4| 8| 3| 4| 0| 4| 1| 4| 4| 1| 5| 6| 4| 5| 0| 9| 5| 5| 5| 5|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    500 PPM                                | 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|     L      |
                                           | 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                 |                                                                          |            |
                                           |                                                                          |            |
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Adenoma                              |                         X                                                |          1 |
      Fibrosarcoma, Metastatic, Skin       |                                                                          |          1 |
      Leukemia Mononuclear                 |       X                                      X     X     X     X         |         16 |
                                           |__________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Ear                                     |                                                                          |   1        |
                                           |__________________________________________________________________________|____________|
   Eye                                     |                      +                                                   |   4        |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |       X                                      X     X     X               |         13 |
      Stromal Nephroma                     |                                                                          |          1 |
                                           |__________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |                                                    X                     |          4 |
 __________________________________________________________________________________________________________________________________ 
 SYSTEMIC LESIONS                          |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Multiple Organs                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |       X                                      X     X     X     X         |         16 |
 __________________________________________________________________________________________________________________________________ 
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  22                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 5| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 6| 7| 6| 7| 7|             
                             DAY ON TEST   | 3| 0| 2| 3| 3| 3| 0| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 0| 3| 2| 0| 3|             
                                           | 3| 1| 2| 3| 3| 3| 6| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 7| 5| 0| 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   | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5|             
    2000 PPM                               | 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                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  I  +  +  +  I  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  A  +|             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  A  +|             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  A  +|             
      Leiomyosarcoma                       |                                                 X                        |             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  A  +|             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X  X     X           X        X  X        X        X     X  X            |             
                                           |__________________________________________________________________________|             
   Mesentery                               | +  +  +                                +                 +  +  +  +      |             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  23                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 5| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 6| 7| 6| 7| 7|             
                             DAY ON TEST   | 3| 0| 2| 3| 3| 3| 0| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 0| 3| 2| 0| 3|             
                                           | 3| 1| 2| 3| 3| 3| 6| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 7| 5| 0| 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   | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5|             
    2000 PPM                               | 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 - cont                  |                                                                          |             
                                           |                                                                          |             
   Tooth                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |__________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|             
      Leukemia Mononuclear                 | X  X     X           X                                      X            |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |__________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|             
      Adenoma                              |                                                 X                        |             
      Leukemia Mononuclear                 | X  X     X                    X                          X  X            |             
                                           |__________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|             
      Leukemia Mononuclear                 | X  X     X                    X                          X  X            |             
      Pheochromocytoma Benign              |                X     X                          X                        |             
      Bilateral, Pheochromocytoma Benign   |                                                                          |             
                                           |__________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|             
                                           |__________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|             
                                           |__________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X  X                                                     X  X            |             
      Pars Distalis, Adenoma               |    X  X  X  X  X  X     X  X  X  X  X  X  X  X     X     X     X  X  X   |             
                                           |__________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|             
      C-Cell, Adenoma                      |                            X                                X            |             
      C-Cell, Carcinoma                    |    X                                X              X           X         |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |__________________________________________________________________________|             
   Clitoral Gland                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +|             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  24                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 5| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 6| 7| 6| 7| 7|             
                             DAY ON TEST   | 3| 0| 2| 3| 3| 3| 0| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 0| 3| 2| 0| 3|             
                                           | 3| 1| 2| 3| 3| 3| 6| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 7| 5| 0| 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   | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5|             
    2000 PPM                               | 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                     |                                                                          |             
                                           |                                                                          |             
      Adenoma                              |                X                          X  X           X        X      |             
      Carcinoma                            |          X                                         X                    X|             
                                           |__________________________________________________________________________|             
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X  X     X                                                  X            |             
                                           |__________________________________________________________________________|             
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Polyp Stromal                        |             X        X  X  X                          X                  |             
      Polyp Stromal, Multiple              | X                                                                        |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |__________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|             
      Leukemia Mononuclear                 | X        X                                               X  X            |             
                                           |__________________________________________________________________________|             
   Lymph Node                              |                                                          +               |             
      Iliac, Leukemia Mononuclear          |                                                                          |             
      Pancreatic, Leukemia Mononuclear     |                                                          X               |             
      Renal, Leukemia Mononuclear          |                                                                          |             
                                           |__________________________________________________________________________|             
   Lymph Node, Bronchial                   | M  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  M  M  +  M  +  +  +|             
      Leukemia Mononuclear                 |    X     X           X        X  X        X                 X            |             
                                           |__________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|             
      Leukemia Mononuclear                 | X  X     X           X        X  X        X              X  X            |             
                                           |__________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +|             
      Leukemia Mononuclear                 | X  X     X           X        X  X        X              X  X            |             
                                           |__________________________________________________________________________|             
   Lymph Node, Mediastinal                 | +  +  +  +  +  +  +  +  +  M  +  +  +  M  +  +  +  M  M  +  +  +  +  M  M|             
      Leukemia Mononuclear                 | X  X     X                       X        X              X  X            |             
                                           |__________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|             
      Leukemia Mononuclear                 | X  X     X           X        X  X        X        X     X  X            |             
                                           |__________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  M  +  +  +  +  M  +  +  +  +  +  +  +  +  M  +  +  +  +  M|             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  25                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 5| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 6| 7| 6| 7| 7|             
                             DAY ON TEST   | 3| 0| 2| 3| 3| 3| 0| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 0| 3| 2| 0| 3|             
                                           | 3| 1| 2| 3| 3| 3| 6| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 7| 5| 0| 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   | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5|             
    2000 PPM                               | 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|             
 __________________________________________|__________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Leukemia Mononuclear                 |                                                             X            |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |__________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Adenoma                              |                            X                                             |             
      Carcinoma                            |    X                             X                                       |             
      Fibroadenoma                         | X                 X           X  X     X  X     X  X  X           X  X   |             
      Fibroadenoma, Multiple               |             X  X        X                    X                 X        X|             
                                           |__________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Keratoacanthoma                      |                                                                          |             
      Squamous Cell Papilloma              |                      X                                                   |             
      Subcutaneous Tissue, Fibroma         |                                                       X                  |             
      Subcutaneous Tissue, Melanoma        |                                                                          |             
          Malignant                        |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |__________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |__________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |__________________________________________________________________________|             
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Carcinoma, Metastatic, Thyroid Gland |                                     X                                    |             
      Leukemia Mononuclear                 | X  X     X           X        X  X        X        X     X  X            |             
                                           |__________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  26                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 5| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 6| 7| 6| 7| 7|             
                             DAY ON TEST   | 3| 0| 2| 3| 3| 3| 0| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 0| 3| 2| 0| 3|             
                                           | 3| 1| 2| 3| 3| 3| 6| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 7| 5| 0| 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   | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5|             
    2000 PPM                               | 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                     |                                                                          |             
                                           |__________________________________________________________________________|             
   Eye                                     |                      +                    +           +                 +|             
                                           |__________________________________________________________________________|             
   Zymbal's Gland                          |                                                                          |             
      Carcinoma                            |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |__________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|             
      Leukemia Mononuclear                 | X  X     X           X        X  X        X              X  X            |             
                                           |__________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|             
      Leukemia Mononuclear                 |                                                                          |             
      Transitional Epithelium, Papilloma   |                                                                          |             
 __________________________________________|__________________________________________________________________________|             
 SYSTEMIC LESIONS                          |                                                                          |             
                                            __________________________________________________________________________|             
   Multiple Organs                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X  X     X           X        X  X        X        X     X  X            |             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  27                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 6| 7| 7| 7| 7| 7| 7| 7| 7| 6| 6| 3| 6| 7| 7| 7| 6| 5| 7| 7| 6| 5| 7| 7| 5|            |
                             DAY ON TEST   | 2| 3| 3| 3| 3| 3| 3| 3| 3| 8| 8| 9| 4| 3| 3| 3| 8| 6| 2| 3| 5| 5| 3| 3| 3|            |
                                           | 6| 5| 5| 5| 5| 5| 5| 5| 5| 4| 0| 9| 4| 5| 5| 5| 6| 0| 0| 5| 1| 2| 5| 5| 4|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               ANIMAL ID   | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5|     A      |
    2000 PPM                               | 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|     L      |
                                           | 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                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |                                                             X            |          1 |
                                           |__________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  I  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  47        |
                                           |__________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      Leukemia Mononuclear                 |                                                             X            |          1 |
                                           |__________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      Leukemia Mononuclear                 |                                                             X            |          1 |
                                           |__________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      Leiomyosarcoma                       |                                                                          |          1 |
      Leukemia Mononuclear                 |                                                             X  X         |          2 |
                                           |__________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      Leukemia Mononuclear                 |                                                             X            |          1 |
                                           |__________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 | X     X        X           X        X     X  X        X  X  X  X        X|         22 |
                                           |__________________________________________________________________________|____________|
   Mesentery                               |                            +           +           +        +            |  12        |
      Leukemia Mononuclear                 |                                                             X            |          1 |
                                           |__________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |                                                             X            |          1 |
                                           |__________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  28                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 6| 7| 7| 7| 7| 7| 7| 7| 7| 6| 6| 3| 6| 7| 7| 7| 6| 5| 7| 7| 6| 5| 7| 7| 5|            |
                             DAY ON TEST   | 2| 3| 3| 3| 3| 3| 3| 3| 3| 8| 8| 9| 4| 3| 3| 3| 8| 6| 2| 3| 5| 5| 3| 3| 3|            |
                                           | 6| 5| 5| 5| 5| 5| 5| 5| 5| 4| 0| 9| 4| 5| 5| 5| 6| 0| 0| 5| 1| 2| 5| 5| 4|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               ANIMAL ID   | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5|     A      |
    2000 PPM                               | 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|     L      |
                                           | 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 - cont                  |                                                                          |            |
                                           |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                                                         X|          1 |
                                           |__________________________________________________________________________|____________|
   Tooth                                   |                                                             +            |   1        |
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |                                                             X           X|          7 |
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Adenoma                              |                                                                          |          1 |
      Leukemia Mononuclear                 | X                                   X     X           X  X  X           X|         13 |
                                           |__________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 | X                                   X     X           X  X  X           X|         13 |
      Pheochromocytoma Benign              | X        X     X                                X           X        X   |          9 |
      Bilateral, Pheochromocytoma Benign   |                                                                   X      |          1 |
                                           |__________________________________________________________________________|____________|
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                           |__________________________________________________________________________|____________|
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                           |__________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                                          X  X           X|          7 |
      Pars Distalis, Adenoma               |    X  X        X  X  X  X  X     X  X     X  X  X  X     X  X     X  X  X|         37 |
                                           |__________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      C-Cell, Adenoma                      |                                                                X         |          3 |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  29                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 6| 7| 7| 7| 7| 7| 7| 7| 7| 6| 6| 3| 6| 7| 7| 7| 6| 5| 7| 7| 6| 5| 7| 7| 5|            |
                             DAY ON TEST   | 2| 3| 3| 3| 3| 3| 3| 3| 3| 8| 8| 9| 4| 3| 3| 3| 8| 6| 2| 3| 5| 5| 3| 3| 3|            |
                                           | 6| 5| 5| 5| 5| 5| 5| 5| 5| 4| 0| 9| 4| 5| 5| 5| 6| 0| 0| 5| 1| 2| 5| 5| 4|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               ANIMAL ID   | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5|     A      |
    2000 PPM                               | 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|     L      |
                                           | 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|            |
 _____________________________________________________________________________________________________________________|____________|
 ENDOCRINE SYSTEM - cont                   |                                                                          |            |
                                           |                                                                          |            |
      C-Cell, Carcinoma                    |          X                                                              X|          6 |
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Clitoral Gland                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  M  +  +  +|  47        |
      Adenoma                              |                                                 X                        |          6 |
      Carcinoma                            |                      X                                X                  |          5 |
                                           |__________________________________________________________________________|____________|
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                                       X     X           X|          7 |
                                           |__________________________________________________________________________|____________|
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Polyp Stromal                        | X                                            X                           |          7 |
      Polyp Stromal, Multiple              |                                                                          |          1 |
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 | X                                                     X  X  X  X        X|         10 |
                                           |__________________________________________________________________________|____________|
   Lymph Node                              | +                                                                       +|   3        |
      Iliac, Leukemia Mononuclear          | X                                                                        |          1 |
      Pancreatic, Leukemia Mononuclear     |                                                                         X|          2 |
      Renal, Leukemia Mononuclear          | X                                                                        |          1 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Bronchial                   | +  +  +  M  +  M  M  M  M  +  +  +  +  M  +  +  M  M  +  +  M  +  +  +  +|  36        |
      Leukemia Mononuclear                 | X     X                    X        X     X           X  X              X|         15 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  M  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  47        |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  30                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 6| 7| 7| 7| 7| 7| 7| 7| 7| 6| 6| 3| 6| 7| 7| 7| 6| 5| 7| 7| 6| 5| 7| 7| 5|            |
                             DAY ON TEST   | 2| 3| 3| 3| 3| 3| 3| 3| 3| 8| 8| 9| 4| 3| 3| 3| 8| 6| 2| 3| 5| 5| 3| 3| 3|            |
                                           | 6| 5| 5| 5| 5| 5| 5| 5| 5| 4| 0| 9| 4| 5| 5| 5| 6| 0| 0| 5| 1| 2| 5| 5| 4|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               ANIMAL ID   | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5|     A      |
    2000 PPM                               | 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|     L      |
                                           | 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               |                                                                          |            |
                                           |                                                                          |            |
      Leukemia Mononuclear                 | X     X                    X        X     X           X  X  X  X        X|         19 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 | X     X                    X        X     X           X  X  X  X        X|         19 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Mediastinal                 | +  +  M  +  +  +  +  +  M  +  M  M  +  +  +  +  +  +  +  +  +  M  +  +  +|  39        |
      Leukemia Mononuclear                 | X                          X        X     X           X  X  X           X|         15 |
                                           |__________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 | X     X        X           X        X     X  X        X  X  X  X        X|         22 |
                                           |__________________________________________________________________________|____________|
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +|  45        |
      Leukemia Mononuclear                 |                                     X     X           X  X               |          5 |
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Adenoma                              |                                                                          |          1 |
      Carcinoma                            |       X           X                                                      |          4 |
      Fibroadenoma                         |    X  X  X        X  X  X  X  X        X     X  X  X     X               |         24 |
      Fibroadenoma, Multiple               |                                                                          |          6 |
                                           |__________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Keratoacanthoma                      |                                                             X            |          1 |
      Squamous Cell Papilloma              |                                                                          |          1 |
      Subcutaneous Tissue, Fibroma         |                                                                          |          1 |
      Subcutaneous Tissue, Melanoma        |                                                                          |            |
          Malignant                        |                                                                X         |          1 |
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  31                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 6| 7| 7| 7| 7| 7| 7| 7| 7| 6| 6| 3| 6| 7| 7| 7| 6| 5| 7| 7| 6| 5| 7| 7| 5|            |
                             DAY ON TEST   | 2| 3| 3| 3| 3| 3| 3| 3| 3| 8| 8| 9| 4| 3| 3| 3| 8| 6| 2| 3| 5| 5| 3| 3| 3|            |
                                           | 6| 5| 5| 5| 5| 5| 5| 5| 5| 4| 0| 9| 4| 5| 5| 5| 6| 0| 0| 5| 1| 2| 5| 5| 4|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               ANIMAL ID   | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5|     A      |
    2000 PPM                               | 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|     L      |
                                           | 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|            |
 _____________________________________________________________________________________________________________________|____________|
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Carcinoma, Metastatic, Thyroid Gland |          X                                                               |          2 |
      Leukemia Mononuclear                 | X     X                    X        X     X           X  X  X  X        X|         20 |
                                           |__________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Eye                                     |                         +     +                                          |   6        |
                                           |__________________________________________________________________________|____________|
   Zymbal's Gland                          |                               +                                          |   1        |
      Carcinoma                            |                               X                                          |          1 |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 | X     X                             X                 X  X  X           X|         16 |
                                           |__________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |                                                          X               |          1 |
      Transitional Epithelium, Papilloma   |    X                                                                     |          1 |
 __________________________________________________________________________________________________________________________________ 
 SYSTEMIC LESIONS                          |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Multiple Organs                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 | X     X        X           X        X     X  X        X  X  X  X        X|         22 |
 __________________________________________________________________________________________________________________________________ 
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                             Page  32                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 6| 7| 6| 7| 7| 5| 7| 6| 5| 7| 6| 6| 7| 7| 7| 7| 5| 7| 7| 7| 6| 4| 5|             
                             DAY ON TEST   | 6| 0| 5| 3| 2| 3| 2| 9| 3| 6| 4| 3| 3| 7| 3| 3| 3| 3| 0| 3| 3| 0| 6| 0| 8|             
                                           | 4| 6| 0| 3| 8| 3| 9| 7| 3| 3| 7| 3| 0| 4| 4| 4| 4| 4| 0| 4| 4| 2| 8| 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| 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   | 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7|             
    8000 PPM                               | 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                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                                                      X   |             
                                           |__________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  I  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|             
                                           |__________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  A  +|             
                                           |__________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  A  +|             
                                           |__________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hepatocellular Carcinoma             |                                                                          |             
      Leukemia Mononuclear                 |    X                          X     X  X              X              X   |             
                                           |__________________________________________________________________________|             
   Mesentery                               | +                                   +                          +         |             
                                           |__________________________________________________________________________|             
   Oral Mucosa                             |             +                                                            |             
      Pharyngeal, Squamous Cell Papilloma  |             X                                                            |             
                                           |__________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                        X                             X   |             
                                           |__________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                     X                                    |             
                                           |__________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                     X                                    |             
                                           |__________________________________________________________________________|             
   Tongue                                  |                                                                          |             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  33                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 6| 7| 6| 7| 7| 5| 7| 6| 5| 7| 6| 6| 7| 7| 7| 7| 5| 7| 7| 7| 6| 4| 5|             
                             DAY ON TEST   | 6| 0| 5| 3| 2| 3| 2| 9| 3| 6| 4| 3| 3| 7| 3| 3| 3| 3| 0| 3| 3| 0| 6| 0| 8|             
                                           | 4| 6| 0| 3| 8| 3| 9| 7| 3| 3| 7| 3| 0| 4| 4| 4| 4| 4| 0| 4| 4| 2| 8| 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| 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   | 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7|             
    8000 PPM                               | 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                     |                                                                          |             
                                           |__________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |    X                                X  X                             X   |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |__________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Adenoma                              |                                                                          |             
      Leukemia Mononuclear                 |    X                                X  X                             X   |             
                                           |__________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |    X                                X  X                             X   |             
      Pheochromocytoma Benign              |    X  X                 X                                                |             
                                           |__________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                     X  X                                 |             
      Pars Distalis, Adenoma               | X     X  X     X  X  X  X  X     X        X  X  X     X  X  X  X  X      |             
                                           |__________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Adenoma                      |          X                 X           X  X                              |             
      C-Cell, Carcinoma                    |                   X                                                      |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |__________________________________________________________________________|             
   Clitoral Gland                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Carcinoma                            |                                  X                                       |             
                                           |__________________________________________________________________________|             
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Granulosa Cell Tumor Malignant       |                                                                          |             
      Leukemia Mononuclear                 |                                     X  X                             X   |             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  34                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 6| 7| 6| 7| 7| 5| 7| 6| 5| 7| 6| 6| 7| 7| 7| 7| 5| 7| 7| 7| 6| 4| 5|             
                             DAY ON TEST   | 6| 0| 5| 3| 2| 3| 2| 9| 3| 6| 4| 3| 3| 7| 3| 3| 3| 3| 0| 3| 3| 0| 6| 0| 8|             
                                           | 4| 6| 0| 3| 8| 3| 9| 7| 3| 3| 7| 3| 0| 4| 4| 4| 4| 4| 0| 4| 4| 2| 8| 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| 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   | 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7|             
    8000 PPM                               | 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                     |                                                                          |             
                                           |                                                                          |             
                                           |__________________________________________________________________________|             
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                        X                             X   |             
      Polyp Stromal                        |                                           X                          X   |             
      Polyp Stromal, Multiple              |                                                                         X|             
                                           |__________________________________________________________________________|             
   Vagina                                  |                            +                                             |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |__________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |    X                          X     X  X              X                  |             
                                           |__________________________________________________________________________|             
   Lymph Node                              |                                     +                                    |             
      Deep Cervical, Carcinoma, Metastatic,|                                                                          |             
           Thyroid Gland                   |                                                                          |             
      Pancreatic, Leukemia Mononuclear     |                                     X                                    |             
                                           |__________________________________________________________________________|             
   Lymph Node, Bronchial                   | M  +  M  M  +  +  M  +  +  +  M  M  +  M  M  +  +  +  M  +  M  M  M  M  +|             
      Leukemia Mononuclear                 |    X                                X                                    |             
                                           |__________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +|             
      Leukemia Mononuclear                 |    X                          X     X  X              X                  |             
                                           |__________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |    X                          X     X  X              X              X   |             
                                           |__________________________________________________________________________|             
   Lymph Node, Mediastinal                 | +  +  +  M  +  +  +  +  M  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |    X                          X     X  X                             X   |             
                                           |__________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemangiosarcoma                      |                                  X                                       |             
      Leukemia Mononuclear                 |    X                          X     X                 X              X   |             
                                           |__________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  M  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  M  +|             
      Leukemia Mononuclear                 |                                     X  X                                 |             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  35                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 6| 7| 6| 7| 7| 5| 7| 6| 5| 7| 6| 6| 7| 7| 7| 7| 5| 7| 7| 7| 6| 4| 5|             
                             DAY ON TEST   | 6| 0| 5| 3| 2| 3| 2| 9| 3| 6| 4| 3| 3| 7| 3| 3| 3| 3| 0| 3| 3| 0| 6| 0| 8|             
                                           | 4| 6| 0| 3| 8| 3| 9| 7| 3| 3| 7| 3| 0| 4| 4| 4| 4| 4| 0| 4| 4| 2| 8| 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| 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   | 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7|             
    8000 PPM                               | 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                      |                                                                          |             
                                           |__________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Carcinoma                            |          X           X              X                                    |             
      Fibroadenoma                         |       X        X  X     X     X  X     X  X  X           X  X            |             
      Fibroadenoma, Multiple               |                                                 X                        |             
                                           |__________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                                                      X   |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |__________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Skeletal Muscle                         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |__________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |__________________________________________________________________________|             
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Carcinoma, Metastatic, Thyroid Gland |                                                                          |             
      Leukemia Mononuclear                 |    X                          X     X                 X              X   |             
                                           |__________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |__________________________________________________________________________|             
   Eye                                     |                                     +              +                     |             
                                           |__________________________________________________________________________|             
   Lacrimal Gland                          |                                                                          |             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  36                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 6| 7| 6| 7| 7| 5| 7| 6| 5| 7| 6| 6| 7| 7| 7| 7| 5| 7| 7| 7| 6| 4| 5|             
                             DAY ON TEST   | 6| 0| 5| 3| 2| 3| 2| 9| 3| 6| 4| 3| 3| 7| 3| 3| 3| 3| 0| 3| 3| 0| 6| 0| 8|             
                                           | 4| 6| 0| 3| 8| 3| 9| 7| 3| 3| 7| 3| 0| 4| 4| 4| 4| 4| 0| 4| 4| 2| 8| 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| 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   | 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7|             
    8000 PPM                               | 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|             
 __________________________________________|__________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |__________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                               X     X  X              X                  |             
      Lipoma                               |                                                                          |             
                                           |__________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                     X                                    |             
 __________________________________________|__________________________________________________________________________|             
 SYSTEMIC LESIONS                          |                                                                          |             
                                            __________________________________________________________________________|             
   Multiple Organs                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |    X                          X     X  X              X              X   |             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  37                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 7| 6| 7| 5| 7| 7| 5| 7| 4| 6| 6| 6| 0| 7| 7| 7| 5| 5| 7| 7| 7| 6| 7| 7|            |
                             DAY ON TEST   | 2| 3| 4| 3| 5| 3| 3| 1| 3| 6| 8| 9| 7| 0| 3| 3| 2| 9| 1| 3| 3| 3| 5| 3| 3|            |
                                           | 0| 4| 2| 4| 9| 4| 4| 2| 4| 9| 1| 2| 1| 5| 4| 5| 0| 2| 1| 5| 5| 5| 7| 5| 5|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               ANIMAL ID   | 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7|     A      |
    8000 PPM                               | 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|     L      |
                                           | 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                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |                                                                          |          1 |
                                           |__________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  I  +  +  +  +  +  +  +  +  +  +|  48        |
                                           |__________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +|  49        |
                                           |__________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +|  48        |
                                           |__________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +|  47        |
                                           |__________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +|  47        |
                                           |__________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +|  49        |
      Hepatocellular Carcinoma             |                                                             X            |          1 |
      Leukemia Mononuclear                 |       X     X     X  X     X        X           X              X  X     X|         16 |
                                           |__________________________________________________________________________|____________|
   Mesentery                               |    +        +  +                                                  +      |   7        |
                                           |__________________________________________________________________________|____________|
   Oral Mucosa                             |                                                                          |   1        |
      Pharyngeal, Squamous Cell Papilloma  |                                                                          |          1 |
                                           |__________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |                                                                   X      |          3 |
                                           |__________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                                                          |          1 |
                                           |__________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  38                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 7| 6| 7| 5| 7| 7| 5| 7| 4| 6| 6| 6| 0| 7| 7| 7| 5| 5| 7| 7| 7| 6| 7| 7|            |
                             DAY ON TEST   | 2| 3| 4| 3| 5| 3| 3| 1| 3| 6| 8| 9| 7| 0| 3| 3| 2| 9| 1| 3| 3| 3| 5| 3| 3|            |
                                           | 0| 4| 2| 4| 9| 4| 4| 2| 4| 9| 1| 2| 1| 5| 4| 5| 0| 2| 1| 5| 5| 5| 7| 5| 5|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               ANIMAL ID   | 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7|     A      |
    8000 PPM                               | 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|     L      |
                                           | 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 - cont                  |                                                                          |            |
                                           |                                                                          |            |
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |                                                                          |          1 |
                                           |__________________________________________________________________________|____________|
   Tongue                                  |                                                             +            |   1        |
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |       X     X     X  X     X        X                                    |         10 |
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +|  49        |
      Adenoma                              |                               X                                          |          1 |
      Leukemia Mononuclear                 |       X     X     X  X     X                    X              X  X     X|         13 |
                                           |__________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |       X     X     X  X     X                    X              X  X     X|         13 |
      Pheochromocytoma Benign              |                X                                                         |          4 |
                                           |__________________________________________________________________________|____________|
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +|  49        |
                                           |__________________________________________________________________________|____________|
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +|  48        |
                                           |__________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |       X     X     X  X     X                    X                 X      |          9 |
      Pars Distalis, Adenoma               | X  X     X     X  X     X  X  X  X  X     X  X  X        X  X  X  X  X  X|         36 |
                                           |__________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +|  49        |
      C-Cell, Adenoma                      |                                           X                              |          5 |
      C-Cell, Carcinoma                    |                                                                      X   |          2 |
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                             Page  39                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 7| 6| 7| 5| 7| 7| 5| 7| 4| 6| 6| 6| 0| 7| 7| 7| 5| 5| 7| 7| 7| 6| 7| 7|            |
                             DAY ON TEST   | 2| 3| 4| 3| 5| 3| 3| 1| 3| 6| 8| 9| 7| 0| 3| 3| 2| 9| 1| 3| 3| 3| 5| 3| 3|            |
                                           | 0| 4| 2| 4| 9| 4| 4| 2| 4| 9| 1| 2| 1| 5| 4| 5| 0| 2| 1| 5| 5| 5| 7| 5| 5|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               ANIMAL ID   | 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7|     A      |
    8000 PPM                               | 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|     L      |
                                           | 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                            |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Clitoral Gland                          | M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +|  48        |
      Carcinoma                            |                                                                          |          1 |
                                           |__________________________________________________________________________|____________|
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Granulosa Cell Tumor Malignant       |                                                          X               |          1 |
      Leukemia Mononuclear                 |       X     X        X     X        X           X                        |          9 |
                                           |__________________________________________________________________________|____________|
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                                                          |          2 |
      Polyp Stromal                        |                            X                                   X         |          4 |
      Polyp Stromal, Multiple              |                                                                          |          1 |
                                           |__________________________________________________________________________|____________|
   Vagina                                  |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |       X     X        X     X        X           X                 X      |         12 |
                                           |__________________________________________________________________________|____________|
   Lymph Node                              |                                                                      +   |   2        |
      Deep Cervical, Carcinoma, Metastatic,|                                                                          |            |
           Thyroid Gland                   |                                                                      X   |          1 |
      Pancreatic, Leukemia Mononuclear     |                                                                          |          1 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Bronchial                   | M  M  +  +  M  +  +  +  +  M  +  +  +  +  M  M  +  +  M  M  +  M  +  M  +|  27        |
      Leukemia Mononuclear                 |       X           X  X              X           X                 X     X|          9 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +|  47        |
      Leukemia Mononuclear                 |       X     X     X  X     X        X           X                 X     X|         14 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |       X     X     X  X     X        X           X                 X     X|         15 |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  40                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 7| 6| 7| 5| 7| 7| 5| 7| 4| 6| 6| 6| 0| 7| 7| 7| 5| 5| 7| 7| 7| 6| 7| 7|            |
                             DAY ON TEST   | 2| 3| 4| 3| 5| 3| 3| 1| 3| 6| 8| 9| 7| 0| 3| 3| 2| 9| 1| 3| 3| 3| 5| 3| 3|            |
                                           | 0| 4| 2| 4| 9| 4| 4| 2| 4| 9| 1| 2| 1| 5| 4| 5| 0| 2| 1| 5| 5| 5| 7| 5| 5|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               ANIMAL ID   | 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7|     A      |
    8000 PPM                               | 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|     L      |
                                           | 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               |                                                                          |            |
                                           |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Mediastinal                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  M  +  +  +  +  +  +  +  +|  45        |
      Leukemia Mononuclear                 |       X     X     X  X     X        X                             X     X|         13 |
                                           |__________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Hemangiosarcoma                      |                                                                          |          1 |
      Leukemia Mononuclear                 |       X     X     X  X     X        X           X     X        X  X     X|         16 |
                                           |__________________________________________________________________________|____________|
   Thymus                                  | M  +  +  M  +  M  +  M  +  +  +  M  +  +  +  +  +  +  A  +  +  +  +  +  +|  41        |
      Leukemia Mononuclear                 |       X                             X                             X      |          5 |
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Carcinoma                            |                                           X                              |          4 |
      Fibroadenoma                         |       X              X        X  X              X  X  X     X  X     X  X|         22 |
      Fibroadenoma, Multiple               |                X  X     X                 X                              |          5 |
                                           |__________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                                                          |          1 |
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Skeletal Muscle                         |    +                                                                     |   1        |
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  41                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 7| 6| 7| 5| 7| 7| 5| 7| 4| 6| 6| 6| 0| 7| 7| 7| 5| 5| 7| 7| 7| 6| 7| 7|            |
                             DAY ON TEST   | 2| 3| 4| 3| 5| 3| 3| 1| 3| 6| 8| 9| 7| 0| 3| 3| 2| 9| 1| 3| 3| 3| 5| 3| 3|            |
                                           | 0| 4| 2| 4| 9| 4| 4| 2| 4| 9| 1| 2| 1| 5| 4| 5| 0| 2| 1| 5| 5| 5| 7| 5| 5|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               ANIMAL ID   | 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7|     A      |
    8000 PPM                               | 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|     L      |
                                           | 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                 |                                                                          |            |
                                           |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Carcinoma, Metastatic, Thyroid Gland |                                                                      X   |          1 |
      Leukemia Mononuclear                 |       X     X     X  X     X        X           X     X        X  X     X|         16 |
                                           |__________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |             X                                                     X      |          2 |
                                           |__________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Eye                                     |                   +              +                                       |   4        |
                                           |__________________________________________________________________________|____________|
   Lacrimal Gland                          |                                                       +                  |   1        |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |       X     X     X  X     X        X           X                 X     X|         13 |
      Lipoma                               |                                           X                              |          1 |
                                           |__________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |                                     X                                    |          2 |
 __________________________________________________________________________________________________________________________________ 
 SYSTEMIC LESIONS                          |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Multiple Organs                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |       X     X     X  X     X        X           X     X        X  X     X|         17 |
 __________________________________________________________________________________________________________________________________ 
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  42                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 5| 7| 5| 6| 6| 4| 4| 3| 7| 7| 7| 6| 6| 5| 6| 6| 7| 7| 6| 7| 5| 5| 4| 6|             
                             DAY ON TEST   | 4| 6| 3| 4| 3| 3| 6| 7| 7| 3| 3| 3| 5| 6| 5| 9| 3| 1| 2| 2| 0| 8| 7| 7| 8|             
                                           | 5| 0| 3| 4| 3| 9| 7| 7| 9| 3| 3| 3| 0| 6| 2| 1| 6| 9| 0| 8| 6| 0| 4| 6| 3|             
 __________________________________________|__________________________________________________________________________|             
                                           | 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                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Intestine Large, Rectum                 | +  I  +  A  +  +  +  +  +  +  I  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                                                          |             
      Polyp Adenomatous                    |                                                                          |             
                                           |__________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +|             
                                           |__________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  A  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +|             
      Carcinoma                            |                                                 X                        |             
                                           |__________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  A  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +|             
                                           |__________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Histiocytic Sarcoma                  |                                                                          |             
      Leukemia Mononuclear                 |       X           X        X     X  X                    X              X|             
      Osteosarcoma, Metastatic, Bone       |                                  X                                       |             
                                           |__________________________________________________________________________|             
   Mesentery                               | +           +  +     +     +  +  +           +     +                     |             
                                           |__________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Adenoma                              |       X                                      X                           |             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Tongue                                  |                                                    +                     |             
                                           |__________________________________________________________________________|             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  43                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 5| 7| 5| 6| 6| 4| 4| 3| 7| 7| 7| 6| 6| 5| 6| 6| 7| 7| 6| 7| 5| 5| 4| 6|             
                             DAY ON TEST   | 4| 6| 3| 4| 3| 3| 6| 7| 7| 3| 3| 3| 5| 6| 5| 9| 3| 1| 2| 2| 0| 8| 7| 7| 8|             
                                           | 5| 0| 3| 4| 3| 9| 7| 7| 9| 3| 3| 3| 0| 6| 2| 1| 6| 9| 0| 8| 6| 0| 4| 6| 3|             
 __________________________________________|__________________________________________________________________________|             
                                           | 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 - cont                  |                                                                          |             
                                           |                                                                          |             
   Tooth                                   |    +                                            +                        |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |__________________________________________________________________________|             
   Blood Vessel                            |                +                                                         |             
                                           |__________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                   X        X                             X               |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |__________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Adenoma                              |                                                                          |             
      Leukemia Mononuclear                 |       X           X                                      X               |             
      Osteosarcoma, Metastatic, Bone       |                                  X                                       |             
                                           |__________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |       X           X                                      X               |             
      Pheochromocytoma Benign              |             X                 X                 X     X     X     X      |             
      Bilateral, Pheochromocytoma Benign   |                            X     X           X                           |             
                                           |__________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Adenoma                              |                                        X                    X            |             
      Carcinoma                            |                      X        X                                          |             
                                           |__________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |       X           X        X                             X              X|             
      Pars Distalis, Adenoma               | X     X     X  X     X        X  X  X  X  X  X  X  X  X  X  X  X  X  X  X|             
                                           |__________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +|             
      C-Cell, Adenoma                      |                            X     X                                       |             
      Follicular Cell, Carcinoma           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
    None                                   |                                                                          |             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                             Page  44                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 5| 7| 5| 6| 6| 4| 4| 3| 7| 7| 7| 6| 6| 5| 6| 6| 7| 7| 6| 7| 5| 5| 4| 6|             
                             DAY ON TEST   | 4| 6| 3| 4| 3| 3| 6| 7| 7| 3| 3| 3| 5| 6| 5| 9| 3| 1| 2| 2| 0| 8| 7| 7| 8|             
                                           | 5| 0| 3| 4| 3| 9| 7| 7| 9| 3| 3| 3| 0| 6| 2| 1| 6| 9| 0| 8| 6| 0| 4| 6| 3|             
 __________________________________________|__________________________________________________________________________|             
                                           | 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                            |                                                                          |             
                                           |__________________________________________________________________________|             
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Mesothelioma Malignant               | X        X                                                               |             
                                           |__________________________________________________________________________|             
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Adenoma                              |                   X           X                                X         |             
      Carcinoma                            |    X                                                                     |             
                                           |__________________________________________________________________________|             
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Mesothelioma Malignant               |          X                                                               |             
      Bilateral, Interstitial Cell, Adenoma|       X                 X  X  X  X                 X  X                  |             
      Interstitial Cell, Adenoma           |                X                             X           X               |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |__________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |       X           X        X                             X               |             
                                           |__________________________________________________________________________|             
   Lymph Node                              |                +  +              +                                       |             
      Histiocytic Sarcoma                  |                                                                          |             
      Leukemia Mononuclear                 |                                                                          |             
      Iliac, Leukemia Mononuclear          |                                                                          |             
      Iliac, Osteosarcoma, Metastatic, Bone|                                  X                                       |             
      Pancreatic, Leukemia Mononuclear     |                   X                                                      |             
                                           |__________________________________________________________________________|             
   Lymph Node, Bronchial                   | +  M  +  M  M  +  M  M  M  +  +  M  +  +  +  +  +  M  +  M  +  +  M  +  +|             
      Histiocytic Sarcoma                  |                                                                          |             
      Leukemia Mononuclear                 |       X                    X        X                                   X|             
                                           |__________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  M  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                   X        X        X                    X              X|             
                                           |__________________________________________________________________________|             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  45                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 5| 7| 5| 6| 6| 4| 4| 3| 7| 7| 7| 6| 6| 5| 6| 6| 7| 7| 6| 7| 5| 5| 4| 6|             
                             DAY ON TEST   | 4| 6| 3| 4| 3| 3| 6| 7| 7| 3| 3| 3| 5| 6| 5| 9| 3| 1| 2| 2| 0| 8| 7| 7| 8|             
                                           | 5| 0| 3| 4| 3| 9| 7| 7| 9| 3| 3| 3| 0| 6| 2| 1| 6| 9| 0| 8| 6| 0| 4| 6| 3|             
 __________________________________________|__________________________________________________________________________|             
                                           | 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|             
 __________________________________________|__________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |       X           X        X        X                    X              X|             
                                           |__________________________________________________________________________|             
   Lymph Node, Mediastinal                 | M  +  +  +  +  +  +  +  +  +  +  M  +  +  M  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |       X           X        X        X                    X              X|             
                                           |__________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |       X           X        X     X  X                    X              X|             
                                           |__________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  M  +  M  +  +  +  M  +  M  +  +  M  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                   X                                      X               |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |__________________________________________________________________________|             
   Mammary Gland                           | +  M  +  M  +  +  M  M  M  +  +  +  +  +  +  +  +  +  +  M  +  +  +  M  +|             
      Carcinoma, Multiple                  |                                                                          |             
      Fibroadenoma                         |                                                    X                     |             
                                           |__________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Keratoacanthoma                      |                                        X                                 |             
      Subcutaneous Tissue, Fibroma         |                                                                          |             
      Subcutaneous Tissue, Lipoma          | X                                                                        |             
      Subcutaneous Tissue, Sarcoma         |                X                                                         |             
      Subcutaneous Tissue, Schwannoma      |                                                                          |             
          Benign                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |__________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Osteosarcoma                         |                                  X                                       |             
                                           |__________________________________________________________________________|             
   Skeletal Muscle                         |    +                                                                     |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |__________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  46                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 5| 7| 5| 6| 6| 4| 4| 3| 7| 7| 7| 6| 6| 5| 6| 6| 7| 7| 6| 7| 5| 5| 4| 6|             
                             DAY ON TEST   | 4| 6| 3| 4| 3| 3| 6| 7| 7| 3| 3| 3| 5| 6| 5| 9| 3| 1| 2| 2| 0| 8| 7| 7| 8|             
                                           | 5| 0| 3| 4| 3| 9| 7| 7| 9| 3| 3| 3| 0| 6| 2| 1| 6| 9| 0| 8| 6| 0| 4| 6| 3|             
 __________________________________________|__________________________________________________________________________|             
                                           | 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|             
 __________________________________________|__________________________________________________________________________|             
 NERVOUS SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Astrocytoma Malignant                |                         X                                                |             
      Leukemia Mononuclear                 |                   X                                                      |             
      Oligodendroglioma Malignant          |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |__________________________________________________________________________|             
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Alveolar/Bronchiolar Adenoma         |                                                    X                     |             
      Histiocytic Sarcoma                  |                                                                          |             
      Leukemia Mononuclear                 |       X           X        X     X  X                    X              X|             
      Osteosarcoma, Metastatic, Bone       |                                  X                                       |             
                                           |__________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +|             
      Leukemia Mononuclear                 |                   X                                                      |             
                                           |__________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |__________________________________________________________________________|             
   Eye                                     |                +                             +                           |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |__________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |       X           X        X        X                    X              X|             
      Stromal Nephroma                     |                                                                          |             
      Renal Tubule, Adenoma                |                                                    X                     |             
                                           |__________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                                          X               |             
 __________________________________________|__________________________________________________________________________|             
 SYSTEMIC LESIONS                          |                                                                          |             
                                            __________________________________________________________________________|             
   Multiple Organs                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Histiocytic Sarcoma                  |                                                                          |             
      Leukemia Mononuclear                 |       X           X        X     X  X                    X              X|             
      Mesothelioma Malignant               | X        X                                                               |             
 __________________________________________|__________________________________________________________________________|             
                                                             Page  47                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 6| 7| 7| 6| 6| 5| 5| 5| 6| 6| 7| 7| 5| 7| 4| 5| 5| 6| 7| 6| 6| 5| 6| 6| 6|            |
                             DAY ON TEST   | 1| 3| 3| 7| 7| 1| 3| 9| 8| 8| 3| 0| 7| 1| 9| 3| 8| 2| 0| 8| 9| 4| 6| 4| 1|            |
                                           | 6| 3| 3| 0| 8| 6| 9| 0| 1| 4| 3| 6| 6| 9| 5| 9| 0| 1| 5| 3| 2| 0| 1| 8| 4|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    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|     L      |
                                           | 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                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                           |__________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  47        |
      Leukemia Mononuclear                 | X                                                                        |          1 |
      Polyp Adenomatous                    | X                                                                        |          1 |
                                           |__________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
                                           |__________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                           |__________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  47        |
      Carcinoma                            |                                                                          |          1 |
                                           |__________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  47        |
                                           |__________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Histiocytic Sarcoma                  |                                                       X                  |          1 |
      Leukemia Mononuclear                 | X  X  X     X        X  X     X        X              X     X  X  X  X  X|         21 |
      Osteosarcoma, Metastatic, Bone       |                                                                          |          1 |
                                           |__________________________________________________________________________|____________|
   Mesentery                               | +  +           +  +           +                                   +      |  15        |
                                           |__________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Adenoma                              |                                                                          |          2 |
      Leukemia Mononuclear                 |                                                       X     X            |          2 |
                                           |__________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  48                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 6| 7| 7| 6| 6| 5| 5| 5| 6| 6| 7| 7| 5| 7| 4| 5| 5| 6| 7| 6| 6| 5| 6| 6| 6|            |
                             DAY ON TEST   | 1| 3| 3| 7| 7| 1| 3| 9| 8| 8| 3| 0| 7| 1| 9| 3| 8| 2| 0| 8| 9| 4| 6| 4| 1|            |
                                           | 6| 3| 3| 0| 8| 6| 9| 0| 1| 4| 3| 6| 6| 9| 5| 9| 0| 1| 5| 3| 2| 0| 1| 8| 4|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    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|     L      |
                                           | 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 - cont                  |                                                                          |            |
                                           |                                                                          |            |
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Tongue                                  |                                                                          |   1        |
                                           |__________________________________________________________________________|____________|
   Tooth                                   |                                                                          |   2        |
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Blood Vessel                            |                                        +                                 |   2        |
                                           |__________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 | X           X                                         X     X            |          7 |
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Adenoma                              |                         X                                                |          1 |
      Leukemia Mononuclear                 | X  X        X        X                 X              X     X  X     X  X|         13 |
      Osteosarcoma, Metastatic, Bone       |                                                                          |          1 |
                                           |__________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 | X  X        X        X                 X              X     X  X     X  X|         13 |
      Pheochromocytoma Benign              |                   X  X              X                    X  X     X     X|         13 |
      Bilateral, Pheochromocytoma Benign   |    X  X     X                 X        X              X              X   |         10 |
                                           |__________________________________________________________________________|____________|
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Adenoma                              |    X                                                        X            |          4 |
      Carcinoma                            |                                        X                             X   |          4 |
                                           |__________________________________________________________________________|____________|
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                           |__________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  49                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 6| 7| 7| 6| 6| 5| 5| 5| 6| 6| 7| 7| 5| 7| 4| 5| 5| 6| 7| 6| 6| 5| 6| 6| 6|            |
                             DAY ON TEST   | 1| 3| 3| 7| 7| 1| 3| 9| 8| 8| 3| 0| 7| 1| 9| 3| 8| 2| 0| 8| 9| 4| 6| 4| 1|            |
                                           | 6| 3| 3| 0| 8| 6| 9| 0| 1| 4| 3| 6| 6| 9| 5| 9| 0| 1| 5| 3| 2| 0| 1| 8| 4|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    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|     L      |
                                           | 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|            |
 _____________________________________________________________________________________________________________________|____________|
 ENDOCRINE SYSTEM - cont                   |                                                                          |            |
                                           |                                                                          |            |
      Leukemia Mononuclear                 |    X        X                          X              X        X     X  X|         12 |
      Pars Distalis, Adenoma               | X  X  X  X  X  X  X  X  X  X  X  X  X  X  X  X  X  X  X  X  X     X  X   |         43 |
                                           |__________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      C-Cell, Adenoma                      |          X                                            X        X         |          5 |
      Follicular Cell, Carcinoma           |                                                                   X      |          1 |
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Mesothelioma Malignant               |             X                                                            |          3 |
                                           |__________________________________________________________________________|____________|
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Adenoma                              |          X                                                               |          4 |
      Carcinoma                            |                                                                          |          1 |
                                           |__________________________________________________________________________|____________|
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                                             X            |          1 |
                                           |__________________________________________________________________________|____________|
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Mesothelioma Malignant               |             X                                                            |          2 |
      Bilateral, Interstitial Cell, Adenoma| X                 X           X                          X  X  X         |         13 |
      Interstitial Cell, Adenoma           |          X  X           X  X                          X           X     X|         10 |
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  50                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 6| 7| 7| 6| 6| 5| 5| 5| 6| 6| 7| 7| 5| 7| 4| 5| 5| 6| 7| 6| 6| 5| 6| 6| 6|            |
                             DAY ON TEST   | 1| 3| 3| 7| 7| 1| 3| 9| 8| 8| 3| 0| 7| 1| 9| 3| 8| 2| 0| 8| 9| 4| 6| 4| 1|            |
                                           | 6| 3| 3| 0| 8| 6| 9| 0| 1| 4| 3| 6| 6| 9| 5| 9| 0| 1| 5| 3| 2| 0| 1| 8| 4|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    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|     L      |
                                           | 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               |                                                                          |            |
                                           |                                                                          |            |
      Leukemia Mononuclear                 | X  X        X        X                 X              X     X  X     X  X|         14 |
                                           |__________________________________________________________________________|____________|
   Lymph Node                              |                                                       +                  |   4        |
      Histiocytic Sarcoma                  |                                                       X                  |          1 |
      Leukemia Mononuclear                 |                                                       X                  |          1 |
      Iliac, Leukemia Mononuclear          |                                                       X                  |          1 |
      Iliac, Osteosarcoma, Metastatic, Bone|                                                                          |          1 |
      Pancreatic, Leukemia Mononuclear     |                                                       X                  |          2 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Bronchial                   | +  M  +  M  +  +  +  +  +  +  M  M  M  +  M  M  +  M  +  +  +  M  M  +  +|  30        |
      Histiocytic Sarcoma                  |                                                       X                  |          1 |
      Leukemia Mononuclear                 | X           X        X  X              X              X     X        X  X|         13 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +|  47        |
      Leukemia Mononuclear                 | X  X        X        X                 X              X     X  X  X  X  X|         16 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 | X  X        X        X                 X              X     X  X  X  X  X|         17 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Mediastinal                 | +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  46        |
      Leukemia Mononuclear                 | X  X        X        X                 X              X     X  X  X  X  X|         17 |
                                           |__________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 | X  X  X     X        X  X     X        X              X     X  X  X  X  X|         21 |
                                           |__________________________________________________________________________|____________|
   Thymus                                  | +  +  +  M  +  +  +  +  +  +  +  +  M  +  M  M  +  +  +  +  +  +  M  +  +|  40        |
      Leukemia Mononuclear                 |             X        X                 X              X     X            |          7 |
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Mammary Gland                           | +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +|  41        |
      Carcinoma, Multiple                  |                         X                                                |          1 |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  51                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 6| 7| 7| 6| 6| 5| 5| 5| 6| 6| 7| 7| 5| 7| 4| 5| 5| 6| 7| 6| 6| 5| 6| 6| 6|            |
                             DAY ON TEST   | 1| 3| 3| 7| 7| 1| 3| 9| 8| 8| 3| 0| 7| 1| 9| 3| 8| 2| 0| 8| 9| 4| 6| 4| 1|            |
                                           | 6| 3| 3| 0| 8| 6| 9| 0| 1| 4| 3| 6| 6| 9| 5| 9| 0| 1| 5| 3| 2| 0| 1| 8| 4|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    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|     L      |
                                           | 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               |                                                                          |            |
                                           |                                                                          |            |
      Fibroadenoma                         |                                                                          |          1 |
                                           |__________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Keratoacanthoma                      |    X                                               X                     |          3 |
      Subcutaneous Tissue, Fibroma         |                                                                      X   |          1 |
      Subcutaneous Tissue, Lipoma          |                                                                          |          1 |
      Subcutaneous Tissue, Sarcoma         |                                                                          |          1 |
      Subcutaneous Tissue, Schwannoma      |                                                                          |            |
          Benign                           |                            X                                             |          1 |
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Osteosarcoma                         |                                                                          |          1 |
                                           |__________________________________________________________________________|____________|
   Skeletal Muscle                         |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Astrocytoma Malignant                |                                                                          |          1 |
      Leukemia Mononuclear                 |             X                                         X                  |          3 |
      Oligodendroglioma Malignant          |                                                    X                     |          1 |
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Alveolar/Bronchiolar Adenoma         |                                                 X                        |          2 |
      Histiocytic Sarcoma                  |                                                       X                  |          1 |
      Leukemia Mononuclear                 | X  X        X        X  X              X              X     X  X  X  X  X|         19 |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  52                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 6| 7| 7| 6| 6| 5| 5| 5| 6| 6| 7| 7| 5| 7| 4| 5| 5| 6| 7| 6| 6| 5| 6| 6| 6|            |
                             DAY ON TEST   | 1| 3| 3| 7| 7| 1| 3| 9| 8| 8| 3| 0| 7| 1| 9| 3| 8| 2| 0| 8| 9| 4| 6| 4| 1|            |
                                           | 6| 3| 3| 0| 8| 6| 9| 0| 1| 4| 3| 6| 6| 9| 5| 9| 0| 1| 5| 3| 2| 0| 1| 8| 4|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    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|     L      |
                                           | 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                 |                                                                          |            |
                                           |                                                                          |            |
      Osteosarcoma, Metastatic, Bone       |                                                                          |          1 |
                                           |__________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |                                        X                                 |          2 |
                                           |__________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Eye                                     |                                        +                                 |   3        |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 | X  X        X        X                 X              X     X  X        X|         15 |
      Stromal Nephroma                     |                                              X                           |          1 |
      Renal Tubule, Adenoma                |                                        X                                 |          2 |
                                           |__________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |             X                          X              X                  |          4 |
 __________________________________________________________________________________________________________________________________ 
 SYSTEMIC LESIONS                          |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Multiple Organs                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Histiocytic Sarcoma                  |                                                       X                  |          1 |
      Leukemia Mononuclear                 | X  X  X     X        X  X     X        X              X     X  X  X  X  X|         21 |
      Mesothelioma Malignant               |             X                                                            |          3 |
 __________________________________________________________________________________________________________________________________ 
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  53                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 5| 5| 6| 5| 6| 6| 7| 6| 5| 5| 6| 6| 6| 6| 6| 6| 5| 6| 6| 5| 5| 5| 6| 5|             
                             DAY ON TEST   | 6| 7| 6| 4| 4| 6| 9| 3| 2| 2| 2| 6| 7| 7| 7| 7| 2| 8| 3| 1| 2| 9| 5| 8| 3|             
                                           | 4| 9| 0| 2| 7| 2| 2| 3| 4| 6| 6| 0| 1| 1| 0| 8| 7| 3| 2| 4| 3| 2| 2| 4| 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 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|             
    500 PPM                                | 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                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |    X  X              X  X     X  X                    X     X     X     X|             
                                           |__________________________________________________________________________|             
   Mesentery                               |          +                       +                                   +   |             
      Liposarcoma                          |                                                                          |             
                                           |__________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Adenoma                              |                                                                          |             
      Leukemia Mononuclear                 |    X                          X                                   X      |             
                                           |__________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                  X                                       |             
                                           |__________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                  X                                       |             
                                           |__________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  54                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 5| 5| 6| 5| 6| 6| 7| 6| 5| 5| 6| 6| 6| 6| 6| 6| 5| 6| 6| 5| 5| 5| 6| 5|             
                             DAY ON TEST   | 6| 7| 6| 4| 4| 6| 9| 3| 2| 2| 2| 6| 7| 7| 7| 7| 2| 8| 3| 1| 2| 9| 5| 8| 3|             
                                           | 4| 9| 0| 2| 7| 2| 2| 3| 4| 6| 6| 0| 1| 1| 0| 8| 7| 3| 2| 4| 3| 2| 2| 4| 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 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|             
    500 PPM                                | 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 - cont                  |                                                                          |             
                                           |                                                                          |             
      Leukemia Mononuclear                 |                                                                   X      |             
                                           |__________________________________________________________________________|             
   Tooth                                   |                                                                         +|             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |__________________________________________________________________________|             
   Blood Vessel                            |                                                                      +   |             
                                           |__________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |    X                          X                       X     X           X|             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |__________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |    X  X              X  X     X                       X     X     X     X|             
                                           |__________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |    X  X              X  X     X                       X     X     X     X|             
      Pheochromocytoma Malignant           |                                                                          |             
      Pheochromocytoma Benign              |          X        X                                                  X  X|             
      Bilateral, Pheochromocytoma Benign   | X                          X     X  X     X                              |             
                                           |__________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Carcinoma                            | X                 X                                                      |             
                                           |__________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |    X  X                       X  X                    X     X     X     X|             
      Pars Distalis, Adenoma               | X  X     X  X  X  X     X  X        X  X  X  X  X  X  X  X     X  X  X  X|             
                                           |__________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Adenoma                      |          X     X                                                         |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
    None                                   |                                                                          |             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  55                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 5| 5| 6| 5| 6| 6| 7| 6| 5| 5| 6| 6| 6| 6| 6| 6| 5| 6| 6| 5| 5| 5| 6| 5|             
                             DAY ON TEST   | 6| 7| 6| 4| 4| 6| 9| 3| 2| 2| 2| 6| 7| 7| 7| 7| 2| 8| 3| 1| 2| 9| 5| 8| 3|             
                                           | 4| 9| 0| 2| 7| 2| 2| 3| 4| 6| 6| 0| 1| 1| 0| 8| 7| 3| 2| 4| 3| 2| 2| 4| 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 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|             
    500 PPM                                | 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                            |                                                                          |             
                                           |__________________________________________________________________________|             
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                                       X                  |             
      Mesothelioma Malignant               |             X  X                                                         |             
                                           |__________________________________________________________________________|             
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Adenoma                              |                      X                                                   |             
      Carcinoma                            |                   X        X                                             |             
      Bilateral, Carcinoma                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |    X                                                                     |             
                                           |__________________________________________________________________________|             
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |    X                                                                     |             
      Mesothelioma Malignant               |                X                                                         |             
      Bilateral, Interstitial Cell, Adenoma|       X        X     X           X           X              X        X   |             
      Interstitial Cell, Adenoma           |    X              X        X        X     X     X     X        X        X|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |__________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |    X  X              X  X     X  X                    X     X     X     X|             
                                           |__________________________________________________________________________|             
   Lymph Node                              |       +              +        +                       +           +     +|             
      Pancreatic, Leukemia Mononuclear     |       X                       X                       X           X     X|             
      Renal, Leukemia Mononuclear          |                      X                                                   |             
                                           |__________________________________________________________________________|             
   Lymph Node, Bronchial                   | +  +  +  +  M  +  +  +  +  M  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |    X  X              X           X                    X     X     X     X|             
                                           |__________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M|             
      Leukemia Mononuclear                 |    X  X              X           X                    X     X     X      |             
                                           |__________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  56                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 5| 5| 6| 5| 6| 6| 7| 6| 5| 5| 6| 6| 6| 6| 6| 6| 5| 6| 6| 5| 5| 5| 6| 5|             
                             DAY ON TEST   | 6| 7| 6| 4| 4| 6| 9| 3| 2| 2| 2| 6| 7| 7| 7| 7| 2| 8| 3| 1| 2| 9| 5| 8| 3|             
                                           | 4| 9| 0| 2| 7| 2| 2| 3| 4| 6| 6| 0| 1| 1| 0| 8| 7| 3| 2| 4| 3| 2| 2| 4| 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 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|             
    500 PPM                                | 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|             
 __________________________________________|__________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Leukemia Mononuclear                 |    X  X              X  X     X  X                    X     X     X     X|             
                                           |__________________________________________________________________________|             
   Lymph Node, Mediastinal                 | M  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +|             
      Leukemia Mononuclear                 |    X  X              X        X  X                    X     X     X     X|             
                                           |__________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |    X  X        X     X  X     X  X                    X     X     X     X|             
                                           |__________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  M  M  +  +  M  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |    X                 X                                X           X      |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |__________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  M  +  +  +  +  +  +|             
      Carcinoma                            |                                                          X               |             
                                           |__________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Basal Cell Carcinoma                 |                                                                          |             
      Keratoacanthoma                      | X                                                                 X      |             
      Squamous Cell Papilloma              |                                                                      X   |             
      Sebaceous Gland, Adenoma             |                                                                          |             
      Subcutaneous Tissue, Schwannoma      |                                                                          |             
          Malignant                        |                                                                          |             
      Subcutaneous Tissue, Pinna, Melanoma |                                                                          |             
          Malignant                        |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |__________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Osteosarcoma                         |                                                    X                     |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |__________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |    X                                                        X           X|             
 _____________________________________________________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  57                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 5| 5| 6| 5| 6| 6| 7| 6| 5| 5| 6| 6| 6| 6| 6| 6| 5| 6| 6| 5| 5| 5| 6| 5|             
                             DAY ON TEST   | 6| 7| 6| 4| 4| 6| 9| 3| 2| 2| 2| 6| 7| 7| 7| 7| 2| 8| 3| 1| 2| 9| 5| 8| 3|             
                                           | 4| 9| 0| 2| 7| 2| 2| 3| 4| 6| 6| 0| 1| 1| 0| 8| 7| 3| 2| 4| 3| 2| 2| 4| 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 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|             
    500 PPM                                | 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|             
 __________________________________________|__________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |__________________________________________________________________________|             
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Alveolar/Bronchiolar Adenoma         |    X                                                                     |             
      Alveolar/Bronchiolar Carcinoma       |                                                                          |             
      Leukemia Mononuclear                 |    X  X              X  X     X  X                    X     X     X     X|             
      Mediastinum, Alveolar/Bronchiolar    |                                                                          |             
          Carcinoma, Metastatic, Lung      |                                                                          |             
                                           |__________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |    X                                                        X            |             
                                           |__________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |__________________________________________________________________________|             
   Zymbal's Gland                          |                                                                          |             
      Carcinoma                            |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |__________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |    X  X              X        X  X                    X     X     X     X|             
      Renal Tubule, Adenoma                |                                                                          |             
                                           |__________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |    X                          X  X                    X                  |             
 __________________________________________|__________________________________________________________________________|             
 SYSTEMIC LESIONS                          |                                                                          |             
                                            __________________________________________________________________________|             
   Multiple Organs                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |    X  X        X     X  X     X  X                    X     X     X     X|             
      Mesothelioma Malignant               |             X  X                                                         |             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  58                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 3| 6| 7| 6| 6| 6| 6| 4| 7| 6| 5| 7| 4| 6| 7| 6| 5| 2| 6| 7| 4| 7| 5| 7| 5|            |
                             DAY ON TEST   | 8| 0| 3| 0| 6| 8| 4| 8| 0| 8| 8| 3| 6| 2| 0| 2| 2| 4| 9| 3| 6| 3| 0| 1| 1|            |
                                           | 9| 4| 3| 7| 4| 4| 1| 2| 2| 4| 3| 3| 9| 6| 6| 5| 7| 4| 2| 3| 0| 3| 7| 6| 4|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    500 PPM                                | 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|     L      |
                                           | 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                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Intestine Large, Colon                  | A  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      Leukemia Mononuclear                 |                                                                      X   |          1 |
                                           |__________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |                                                                      X   |          1 |
                                           |__________________________________________________________________________|____________|
   Intestine Large, Cecum                  | A  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +|  47        |
      Leukemia Mononuclear                 |                                                                      X   |          1 |
                                           |__________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                           |__________________________________________________________________________|____________|
   Intestine Small, Jejunum                | A  +  +  +  +  +  A  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +|  46        |
      Leukemia Mononuclear                 |                                                                      X   |          1 |
                                           |__________________________________________________________________________|____________|
   Intestine Small, Ileum                  | A  +  +  +  +  +  A  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +|  46        |
      Leukemia Mononuclear                 |                                                                      X   |          1 |
                                           |__________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |       X           X     X              X              X  X     X     X  X|         19 |
                                           |__________________________________________________________________________|____________|
   Mesentery                               |    +  +        +                 +     +  +           +                  |  10        |
      Liposarcoma                          |                                           X                              |          1 |
                                           |__________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Adenoma                              |                X                                                         |          1 |
      Leukemia Mononuclear                 |                         X                                      X     X  X|          7 |
                                           |__________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                                                X     X   |          3 |
                                           |__________________________________________________________________________|____________|
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  59                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 3| 6| 7| 6| 6| 6| 6| 4| 7| 6| 5| 7| 4| 6| 7| 6| 5| 2| 6| 7| 4| 7| 5| 7| 5|            |
                             DAY ON TEST   | 8| 0| 3| 0| 6| 8| 4| 8| 0| 8| 8| 3| 6| 2| 0| 2| 2| 4| 9| 3| 6| 3| 0| 1| 1|            |
                                           | 9| 4| 3| 7| 4| 4| 1| 2| 2| 4| 3| 3| 9| 6| 6| 5| 7| 4| 2| 3| 0| 3| 7| 6| 4|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    500 PPM                                | 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|     L      |
                                           | 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 - cont                  |                                                                          |            |
                                           |                                                                          |            |
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                                                      X   |          2 |
                                           |__________________________________________________________________________|____________|
   Stomach, Glandular                      | A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |                                                                      X   |          2 |
                                           |__________________________________________________________________________|____________|
   Tooth                                   |             +                                      +                     |   3        |
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Blood Vessel                            |       +                                                                  |   2        |
                                           |__________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                   X     X              X              X        X     X  X|         12 |
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Adrenal Cortex                          | A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |       X                 X              X              X  X     X     X  X|         17 |
                                           |__________________________________________________________________________|____________|
   Adrenal Medulla                         | A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |       X                 X              X              X  X     X     X  X|         17 |
      Pheochromocytoma Malignant           |             X                                                            |          1 |
      Pheochromocytoma Benign              |             X     X                                                  X   |          7 |
      Bilateral, Pheochromocytoma Benign   |       X                 X        X                    X  X     X         |         11 |
                                           |__________________________________________________________________________|____________|
   Islets, Pancreatic                      | A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Carcinoma                            |                                                                          |          2 |
                                           |__________________________________________________________________________|____________|
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Pituitary Gland                         | A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  60                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 3| 6| 7| 6| 6| 6| 6| 4| 7| 6| 5| 7| 4| 6| 7| 6| 5| 2| 6| 7| 4| 7| 5| 7| 5|            |
                             DAY ON TEST   | 8| 0| 3| 0| 6| 8| 4| 8| 0| 8| 8| 3| 6| 2| 0| 2| 2| 4| 9| 3| 6| 3| 0| 1| 1|            |
                                           | 9| 4| 3| 7| 4| 4| 1| 2| 2| 4| 3| 3| 9| 6| 6| 5| 7| 4| 2| 3| 0| 3| 7| 6| 4|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    500 PPM                                | 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|     L      |
                                           | 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|            |
 _____________________________________________________________________________________________________________________|____________|
 ENDOCRINE SYSTEM - cont                   |                                                                          |            |
                                           |                                                                          |            |
      Leukemia Mononuclear                 |                                        X              X  X     X     X  X|         14 |
      Pars Distalis, Adenoma               |    X     X  X  X  X  X  X  X  X  X        X  X  X     X  X  X  X  X  X  X|         40 |
                                           |__________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +  A  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      C-Cell, Adenoma                      |                X              X                                          |          4 |
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                                                          |          1 |
      Mesothelioma Malignant               |                                                                          |          2 |
                                           |__________________________________________________________________________|____________|
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Adenoma                              |                               X                                          |          2 |
      Carcinoma                            |                                                                          |          2 |
      Bilateral, Carcinoma                 |                                           X                              |          1 |
                                           |__________________________________________________________________________|____________|
   Prostate                                | A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                           |__________________________________________________________________________|____________|
   Seminal Vesicle                         | A  +  +  +  +  +  A  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  47        |
      Leukemia Mononuclear                 |                                                                X         |          2 |
                                           |__________________________________________________________________________|____________|
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                                                          |          1 |
      Mesothelioma Malignant               |                                                                          |          1 |
      Bilateral, Interstitial Cell, Adenoma|                         X              X  X  X           X     X     X   |         14 |
      Interstitial Cell, Adenoma           |    X     X        X                                   X     X            |         14 |
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  61                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 3| 6| 7| 6| 6| 6| 6| 4| 7| 6| 5| 7| 4| 6| 7| 6| 5| 2| 6| 7| 4| 7| 5| 7| 5|            |
                             DAY ON TEST   | 8| 0| 3| 0| 6| 8| 4| 8| 0| 8| 8| 3| 6| 2| 0| 2| 2| 4| 9| 3| 6| 3| 0| 1| 1|            |
                                           | 9| 4| 3| 7| 4| 4| 1| 2| 2| 4| 3| 3| 9| 6| 6| 5| 7| 4| 2| 3| 0| 3| 7| 6| 4|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    500 PPM                                | 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|     L      |
                                           | 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               |                                                                          |            |
                                           |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Bone Marrow                             | A  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      Leukemia Mononuclear                 |       X                 X              X              X  X     X     X  X|         18 |
                                           |__________________________________________________________________________|____________|
   Lymph Node                              |                                           +           +  +           +  +|  11        |
      Pancreatic, Leukemia Mononuclear     |                                                       X  X           X  X|          9 |
      Renal, Leukemia Mononuclear          |                                                                      X   |          2 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Bronchial                   | M  +  +  +  +  +  +  M  +  +  +  +  M  +  +  +  M  M  +  +  +  +  M  +  +|  41        |
      Leukemia Mononuclear                 |       X           X     X              X              X  X     X     X  X|         17 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  47        |
      Leukemia Mononuclear                 |       X           X     X              X              X  X     X     X  X|         16 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |       X           X     X              X              X  X     X     X  X|         19 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Mediastinal                 | A  +  +  +  +  +  A  +  +  +  M  +  +  +  +  +  M  +  +  +  M  +  +  +  +|  42        |
      Leukemia Mononuclear                 |       X                 X              X              X  X     X     X  X|         17 |
                                           |__________________________________________________________________________|____________|
   Spleen                                  | A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |    X  X           X     X              X              X  X     X     X  X|         21 |
                                           |__________________________________________________________________________|____________|
   Thymus                                  | A  +  +  +  +  +  A  +  +  +  +  +  +  +  M  +  +  M  +  +  +  +  +  M  +|  42        |
      Leukemia Mononuclear                 |       X                                X                       X        X|          8 |
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Mammary Gland                           | M  +  +  +  +  +  +  M  +  +  +  +  M  M  +  +  +  M  +  +  +  +  M  M  +|  41        |
      Carcinoma                            |                                                                          |          1 |
                                           |__________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  62                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 3| 6| 7| 6| 6| 6| 6| 4| 7| 6| 5| 7| 4| 6| 7| 6| 5| 2| 6| 7| 4| 7| 5| 7| 5|            |
                             DAY ON TEST   | 8| 0| 3| 0| 6| 8| 4| 8| 0| 8| 8| 3| 6| 2| 0| 2| 2| 4| 9| 3| 6| 3| 0| 1| 1|            |
                                           | 9| 4| 3| 7| 4| 4| 1| 2| 2| 4| 3| 3| 9| 6| 6| 5| 7| 4| 2| 3| 0| 3| 7| 6| 4|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    500 PPM                                | 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|     L      |
                                           | 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               |                                                                          |            |
                                           |                                                                          |            |
      Basal Cell Carcinoma                 |          X                       X                                       |          2 |
      Keratoacanthoma                      |       X                    X                                             |          4 |
      Squamous Cell Papilloma              |                                                                          |          1 |
      Sebaceous Gland, Adenoma             |             X              X                                             |          2 |
      Subcutaneous Tissue, Schwannoma      |                                                                          |            |
          Malignant                        |                                     X                                    |          1 |
      Subcutaneous Tissue, Pinna, Melanoma |                                                                          |            |
          Malignant                        |                            X                                             |          1 |
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Osteosarcoma                         |                                                                          |          1 |
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                                       X              X  X|          6 |
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Larynx                                  | A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                           |__________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Alveolar/Bronchiolar Adenoma         |                X                                                         |          2 |
      Alveolar/Bronchiolar Carcinoma       |       X                                               X                  |          2 |
      Leukemia Mononuclear                 |       X           X     X              X              X  X     X     X  X|         19 |
      Mediastinum, Alveolar/Bronchiolar    |                                                                          |            |
          Carcinoma, Metastatic, Lung      |                                                       X                  |          1 |
                                           |__________________________________________________________________________|____________|
   Nose                                    | A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |                                                                      X   |          3 |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  63                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 3| 6| 7| 6| 6| 6| 6| 4| 7| 6| 5| 7| 4| 6| 7| 6| 5| 2| 6| 7| 4| 7| 5| 7| 5|            |
                             DAY ON TEST   | 8| 0| 3| 0| 6| 8| 4| 8| 0| 8| 8| 3| 6| 2| 0| 2| 2| 4| 9| 3| 6| 3| 0| 1| 1|            |
                                           | 9| 4| 3| 7| 4| 4| 1| 2| 2| 4| 3| 3| 9| 6| 6| 5| 7| 4| 2| 3| 0| 3| 7| 6| 4|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    500 PPM                                | 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|     L      |
                                           | 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                 |                                                                          |            |
                                           |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Zymbal's Gland                          |          +        +                                                      |   2        |
      Carcinoma                            |          X        X                                                      |          2 |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |       X           X     X              X              X  X     X     X  X|         18 |
      Renal Tubule, Adenoma                |                X                                                         |          1 |
                                           |__________________________________________________________________________|____________|
   Urinary Bladder                         | A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |                                                                X         |          5 |
 __________________________________________________________________________________________________________________________________ 
 SYSTEMIC LESIONS                          |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Multiple Organs                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |    X  X           X     X              X              X  X     X     X  X|         21 |
      Mesothelioma Malignant               |                                                                          |          2 |
 __________________________________________________________________________________________________________________________________ 
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  64                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 5| 6| 5| 6| 6| 5| 5| 5| 7| 5| 5| 6| 7| 7| 5| 6| 5| 7| 7| 5| 6| 3| 7| 5|             
                             DAY ON TEST   | 9| 6| 2| 8| 1| 5| 5| 7| 1| 0| 1| 7| 7| 1| 0| 5| 7| 9| 0| 3| 2| 5| 5| 0| 8|             
                                           | 7| 5| 0| 5| 4| 0| 8| 4| 2| 6| 6| 9| 8| 4| 6| 1| 1| 0| 1| 3| 0| 4| 2| 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| 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   | 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|             
    2000 PPM                               | 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                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|             
                                           |__________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|             
      Leukemia Mononuclear                 |       X                                                                  |             
                                           |__________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|             
                                           |__________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|             
      Carcinoma                            |                                                                          |             
      Hemangiosarcoma                      |                                                                          |             
                                           |__________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|             
                                           |__________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Histiocytic Sarcoma                  |                                                                          |             
      Leukemia Mononuclear                 | X     X        X                                      X     X  X        X|             
                                           |__________________________________________________________________________|             
   Mesentery                               |                                     +     +     +                        |             
                                           |__________________________________________________________________________|             
   Oral Mucosa                             | +                                                                        |             
      Pharyngeal, Squamous Cell Papilloma  | X                                                                        |             
                                           |__________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |       X                                                                  |             
                                           |__________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  65                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 5| 6| 5| 6| 6| 5| 5| 5| 7| 5| 5| 6| 7| 7| 5| 6| 5| 7| 7| 5| 6| 3| 7| 5|             
                             DAY ON TEST   | 9| 6| 2| 8| 1| 5| 5| 7| 1| 0| 1| 7| 7| 1| 0| 5| 7| 9| 0| 3| 2| 5| 5| 0| 8|             
                                           | 7| 5| 0| 5| 4| 0| 8| 4| 2| 6| 6| 9| 8| 4| 6| 1| 1| 0| 1| 3| 0| 4| 2| 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| 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   | 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|             
    2000 PPM                               | 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 - cont                  |                                                                          |             
                                           |                                                                          |             
   Tooth                                   |                                                                   +      |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |__________________________________________________________________________|             
   Blood Vessel                            |                                                                          |             
                                           |__________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |       X                                                                 X|             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |__________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |       X        X                                      X     X  X        X|             
                                           |__________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |       X        X                                      X     X  X        X|             
      Pheochromocytoma Malignant           |                                                                          |             
      Pheochromocytoma Benign              |                X  X                       X              X               |             
      Bilateral, Pheochromocytoma Benign   |       X  X                 X                          X                 X|             
                                           |__________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Adenoma                              |                                                                          |             
      Carcinoma                            |       X                                                                  |             
                                           |__________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |       X                                               X     X  X         |             
      Pars Distalis, Adenoma               | X  X  X  X  X  X  X  X  X  X  X  X  X  X  X  X  X  X     X           X  X|             
                                           |__________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Adenoma                      |                            X        X                 X                  |             
      C-Cell, Carcinoma                    |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
    None                                   |                                                                          |             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  66                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 5| 6| 5| 6| 6| 5| 5| 5| 7| 5| 5| 6| 7| 7| 5| 6| 5| 7| 7| 5| 6| 3| 7| 5|             
                             DAY ON TEST   | 9| 6| 2| 8| 1| 5| 5| 7| 1| 0| 1| 7| 7| 1| 0| 5| 7| 9| 0| 3| 2| 5| 5| 0| 8|             
                                           | 7| 5| 0| 5| 4| 0| 8| 4| 2| 6| 6| 9| 8| 4| 6| 1| 1| 0| 1| 3| 0| 4| 2| 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| 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   | 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|             
    2000 PPM                               | 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                            |                                                                          |             
                                           |__________________________________________________________________________|             
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Preputial Gland                         | +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Adenoma                              |                                                                X         |             
      Carcinoma                            |          X                                                               |             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |       X                                                                  |             
                                           |__________________________________________________________________________|             
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Bilateral, Interstitial Cell, Adenoma|                                     X  X  X     X     X  X  X            |             
      Interstitial Cell, Adenoma           |       X     X     X  X                             X           X     X   |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |__________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Histiocytic Sarcoma                  |                                                                          |             
      Leukemia Mononuclear                 |       X        X                                      X     X  X        X|             
                                           |__________________________________________________________________________|             
   Lymph Node                              |       +        +                                               +         |             
      Histiocytic Sarcoma                  |                                                                          |             
      Iliac, Leukemia Mononuclear          |                X                                                         |             
      Inguinal, Leukemia Mononuclear       |                                                                          |             
      Pancreatic, Histiocytic Sarcoma      |                                                                          |             
      Pancreatic, Leukemia Mononuclear     |       X                                                        X         |             
      Renal, Leukemia Mononuclear          |       X                                                                  |             
                                           |__________________________________________________________________________|             
   Lymph Node, Bronchial                   | M  M  +  +  +  +  M  +  M  +  M  +  +  +  +  +  +  +  +  +  M  +  M  M  M|             
      Histiocytic Sarcoma                  |                                                                          |             
      Leukemia Mononuclear                 |       X        X                                      X        X         |             
                                           |__________________________________________________________________________|             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  67                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 5| 6| 5| 6| 6| 5| 5| 5| 7| 5| 5| 6| 7| 7| 5| 6| 5| 7| 7| 5| 6| 3| 7| 5|             
                             DAY ON TEST   | 9| 6| 2| 8| 1| 5| 5| 7| 1| 0| 1| 7| 7| 1| 0| 5| 7| 9| 0| 3| 2| 5| 5| 0| 8|             
                                           | 7| 5| 0| 5| 4| 0| 8| 4| 2| 6| 6| 9| 8| 4| 6| 1| 1| 0| 1| 3| 0| 4| 2| 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| 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   | 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|             
    2000 PPM                               | 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|             
 __________________________________________|__________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |       X        X                                      X     X  X        X|             
                                           |__________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |       X        X                                      X     X  X        X|             
                                           |__________________________________________________________________________|             
   Lymph Node, Mediastinal                 | +  +  +  +  +  +  +  M  +  +  M  +  +  +  +  +  +  M  +  +  +  +  M  +  +|             
      Histiocytic Sarcoma                  |                                                                          |             
      Leukemia Mononuclear                 |       X        X                                      X     X  X        X|             
                                           |__________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Histiocytic Sarcoma                  |                                                                          |             
      Leukemia Mononuclear                 | X     X        X                                      X     X  X        X|             
                                           |__________________________________________________________________________|             
   Thymus                                  | M  +  +  +  +  M  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |       X                                               X     X           X|             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |__________________________________________________________________________|             
   Mammary Gland                           | +  +  M  M  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +|             
      Fibroadenoma                         |                                                          X               |             
                                           |__________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Keratoacanthoma                      |                      X                                                   |             
      Squamous Cell Papilloma              |                                                                          |             
      Sebaceous Gland, Adenoma             |                                                                          |             
      Subcutaneous Tissue, Fibroma         |                                     X     X                              |             
      Subcutaneous Tissue, Histiocytic     |                                                                          |             
          Sarcoma                          |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |__________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Skeletal Muscle                         |                                                                          |             
      Histiocytic Sarcoma                  |                                                                          |             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  68                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 5| 6| 5| 6| 6| 5| 5| 5| 7| 5| 5| 6| 7| 7| 5| 6| 5| 7| 7| 5| 6| 3| 7| 5|             
                             DAY ON TEST   | 9| 6| 2| 8| 1| 5| 5| 7| 1| 0| 1| 7| 7| 1| 0| 5| 7| 9| 0| 3| 2| 5| 5| 0| 8|             
                                           | 7| 5| 0| 5| 4| 0| 8| 4| 2| 6| 6| 9| 8| 4| 6| 1| 1| 0| 1| 3| 0| 4| 2| 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| 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   | 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|             
    2000 PPM                               | 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|             
 __________________________________________|__________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |__________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Histiocytic Sarcoma                  |                                                                          |             
      Leukemia Mononuclear                 |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |__________________________________________________________________________|             
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Alveolar/Bronchiolar Adenoma         |                                                                          |             
      Alveolar/Bronchiolar Carcinoma       |                                           X                              |             
      Histiocytic Sarcoma                  |                                                                          |             
      Leukemia Mononuclear                 | X     X        X                                      X     X  X        X|             
                                           |__________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                                       X                  |             
                                           |__________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |__________________________________________________________________________|             
   Eye                                     |                +                                                         |             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Zymbal's Gland                          |                                                                          |             
      Carcinoma                            |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |__________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Histiocytic Sarcoma                  |                                                                          |             
      Leukemia Mononuclear                 |       X        X                                      X     X  X        X|             
      Renal Tubule, Carcinoma              |                                                       X  X               |             
                                           |__________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |       X                                                                  |             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                             Page  69                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________|__________________________________________________________________________              
                                           | 4| 5| 6| 5| 6| 6| 5| 5| 5| 7| 5| 5| 6| 7| 7| 5| 6| 5| 7| 7| 5| 6| 3| 7| 5|             
                             DAY ON TEST   | 9| 6| 2| 8| 1| 5| 5| 7| 1| 0| 1| 7| 7| 1| 0| 5| 7| 9| 0| 3| 2| 5| 5| 0| 8|             
                                           | 7| 5| 0| 5| 4| 0| 8| 4| 2| 6| 6| 9| 8| 4| 6| 1| 1| 0| 1| 3| 0| 4| 2| 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| 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   | 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|             
    2000 PPM                               | 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|             
 _____________________________________________________________________________________________________________________              
 SYSTEMIC LESIONS                          |                                                                          |             
                                            __________________________________________________________________________|             
   Multiple Organs                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Histiocytic Sarcoma                  |                                                                          |             
      Leukemia Mononuclear                 | X     X        X                                      X     X  X        X|             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  70                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 7| 6| 6| 6| 7| 6| 5| 6| 6| 5| 4| 4| 7| 6| 5| 7| 7| 6| 7| 4| 7| 5| 6| 5|            |
                             DAY ON TEST   | 0| 3| 5| 8| 0| 3| 1| 5| 1| 2| 2| 9| 8| 3| 2| 5| 1| 3| 2| 0| 5| 3| 8| 5| 6|            |
                                           | 0| 3| 2| 0| 7| 3| 4| 2| 4| 8| 0| 6| 0| 3| 8| 5| 4| 3| 7| 0| 3| 3| 3| 4| 8|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    2000 PPM                               | 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|     L      |
                                           | 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                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
                                           |__________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |                                                                          |          1 |
                                           |__________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                           |__________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|  47        |
      Carcinoma                            |          X                                                               |          1 |
      Hemangiosarcoma                      |                                                                X         |          1 |
                                           |__________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|  47        |
                                           |__________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Histiocytic Sarcoma                  |                X                 X                                       |          2 |
      Leukemia Mononuclear                 | X        X  X     X  X  X  X           X        X  X  X              X  X|         20 |
                                           |__________________________________________________________________________|____________|
   Mesentery                               |    +                                   +     +           +     +         |   8        |
                                           |__________________________________________________________________________|____________|
   Oral Mucosa                             |                                                                          |   1        |
      Pharyngeal, Squamous Cell Papilloma  |                                                                          |          1 |
                                           |__________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                   X  X                                X                 X|          4 |
                                           |__________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  71                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 7| 6| 6| 6| 7| 6| 5| 6| 6| 5| 4| 4| 7| 6| 5| 7| 7| 6| 7| 4| 7| 5| 6| 5|            |
                             DAY ON TEST   | 0| 3| 5| 8| 0| 3| 1| 5| 1| 2| 2| 9| 8| 3| 2| 5| 1| 3| 2| 0| 5| 3| 8| 5| 6|            |
                                           | 0| 3| 2| 0| 7| 3| 4| 2| 4| 8| 0| 6| 0| 3| 8| 5| 4| 3| 7| 0| 3| 3| 3| 4| 8|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    2000 PPM                               | 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|     L      |
                                           | 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 - cont                  |                                                                          |            |
                                           |                                                                          |            |
      Leukemia Mononuclear                 |                                                                          |          1 |
                                           |__________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Tooth                                   |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Blood Vessel                            |                                     +                    +               |   2        |
                                           |__________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 | X                 X  X                                X              X  X|          8 |
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 | X                 X  X  X  X                    X     X              X  X|         15 |
                                           |__________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 | X                 X     X  X                    X     X              X  X|         14 |
      Pheochromocytoma Malignant           |                                                             X            |          1 |
      Pheochromocytoma Benign              |                                  X     X        X                    X   |          8 |
      Bilateral, Pheochromocytoma Benign   |                X                                         X     X         |          8 |
                                           |__________________________________________________________________________|____________|
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Adenoma                              |                                                 X                        |          1 |
      Carcinoma                            |                                                                          |          1 |
                                           |__________________________________________________________________________|____________|
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +|  49        |
                                           |__________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 | X                 X  X  X                       X     X                 X|         11 |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  72                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 7| 6| 6| 6| 7| 6| 5| 6| 6| 5| 4| 4| 7| 6| 5| 7| 7| 6| 7| 4| 7| 5| 6| 5|            |
                             DAY ON TEST   | 0| 3| 5| 8| 0| 3| 1| 5| 1| 2| 2| 9| 8| 3| 2| 5| 1| 3| 2| 0| 5| 3| 8| 5| 6|            |
                                           | 0| 3| 2| 0| 7| 3| 4| 2| 4| 8| 0| 6| 0| 3| 8| 5| 4| 3| 7| 0| 3| 3| 3| 4| 8|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    2000 PPM                               | 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|     L      |
                                           | 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|            |
 _____________________________________________________________________________________________________________________|____________|
 ENDOCRINE SYSTEM - cont                   |                                                                          |            |
                                           |                                                                          |            |
      Pars Distalis, Adenoma               | X  X  X  X  X  X  X  X  X  X        X  X  X  X  X  X        X     X     X|         40 |
                                           |__________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|  48        |
      C-Cell, Adenoma                      |    X                                            X                        |          5 |
      C-Cell, Carcinoma                    |                               X                                X         |          2 |
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                                       X                  |          1 |
                                           |__________________________________________________________________________|____________|
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Adenoma                              |                            X                                             |          2 |
      Carcinoma                            |                               X                                          |          2 |
      Leukemia Mononuclear                 |                      X                                                   |          1 |
                                           |__________________________________________________________________________|____________|
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                                       X                  |          1 |
                                           |__________________________________________________________________________|____________|
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                      X                                X              X   |          4 |
                                           |__________________________________________________________________________|____________|
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Bilateral, Interstitial Cell, Adenoma|    X     X     X        X     X                 X  X  X  X           X   |         17 |
      Interstitial Cell, Adenoma           | X                                X     X                       X        X|         12 |
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  73                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 7| 6| 6| 6| 7| 6| 5| 6| 6| 5| 4| 4| 7| 6| 5| 7| 7| 6| 7| 4| 7| 5| 6| 5|            |
                             DAY ON TEST   | 0| 3| 5| 8| 0| 3| 1| 5| 1| 2| 2| 9| 8| 3| 2| 5| 1| 3| 2| 0| 5| 3| 8| 5| 6|            |
                                           | 0| 3| 2| 0| 7| 3| 4| 2| 4| 8| 0| 6| 0| 3| 8| 5| 4| 3| 7| 0| 3| 3| 3| 4| 8|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    2000 PPM                               | 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|     L      |
                                           | 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               |                                                                          |            |
                                           |                                                                          |            |
      Histiocytic Sarcoma                  |                X                 X                                       |          2 |
      Leukemia Mononuclear                 | X                 X  X  X  X                    X  X  X              X  X|         16 |
                                           |__________________________________________________________________________|____________|
   Lymph Node                              | +              +     +        +        +           +  +                  |  10        |
      Histiocytic Sarcoma                  |                X                                                         |          1 |
      Iliac, Leukemia Mononuclear          |                                                                          |          1 |
      Inguinal, Leukemia Mononuclear       |                                                       X                  |          1 |
      Pancreatic, Histiocytic Sarcoma      |                X                                                         |          1 |
      Pancreatic, Leukemia Mononuclear     | X                    X                 X              X                  |          6 |
      Renal, Leukemia Mononuclear          |                                                    X                     |          2 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Bronchial                   | +  +  +  M  M  +  +  M  +  +  +  +  M  +  +  M  +  M  +  +  +  +  +  +  +|  35        |
      Histiocytic Sarcoma                  |                X                 X                                       |          2 |
      Leukemia Mononuclear                 | X                 X     X  X           X        X     X              X  X|         13 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 | X        X        X  X  X  X           X        X  X  X              X  X|         18 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 | X        X  X     X  X  X  X           X        X  X  X              X  X|         19 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Mediastinal                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  M|  44        |
      Histiocytic Sarcoma                  |                                  X                                       |          1 |
      Leukemia Mononuclear                 | X        X  X     X  X  X  X           X        X  X  X              X   |         18 |
                                           |__________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Histiocytic Sarcoma                  |                                  X                                       |          1 |
      Leukemia Mononuclear                 | X        X  X     X  X  X  X           X        X  X  X              X  X|         20 |
                                           |__________________________________________________________________________|____________|
   Thymus                                  | +  +  M  M  +  +  M  +  M  +  +  M  M  +  +  +  M  +  M  +  M  +  +  +  +|  38        |
      Leukemia Mononuclear                 | X                    X     X                                            X|          8 |
 _____________________________________________________________________________________________________________________|            |
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  74                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 7| 6| 6| 6| 7| 6| 5| 6| 6| 5| 4| 4| 7| 6| 5| 7| 7| 6| 7| 4| 7| 5| 6| 5|            |
                             DAY ON TEST   | 0| 3| 5| 8| 0| 3| 1| 5| 1| 2| 2| 9| 8| 3| 2| 5| 1| 3| 2| 0| 5| 3| 8| 5| 6|            |
                                           | 0| 3| 2| 0| 7| 3| 4| 2| 4| 8| 0| 6| 0| 3| 8| 5| 4| 3| 7| 0| 3| 3| 3| 4| 8|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    2000 PPM                               | 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|     L      |
                                           | 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                      |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Mammary Gland                           | M  +  +  +  +  +  +  +  +  M  M  +  +  M  M  +  +  I  +  +  M  +  +  +  +|  40        |
      Fibroadenoma                         |                                                                          |          1 |
                                           |__________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Keratoacanthoma                      |    X                                                                     |          2 |
      Squamous Cell Papilloma              |    X                                                                 X   |          2 |
      Sebaceous Gland, Adenoma             |                                                          X               |          1 |
      Subcutaneous Tissue, Fibroma         |                                                                          |          2 |
      Subcutaneous Tissue, Histiocytic     |                                                                          |            |
          Sarcoma                          |                X                                                         |          1 |
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Skeletal Muscle                         |                +                                                         |   1        |
      Histiocytic Sarcoma                  |                X                                                         |          1 |
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Histiocytic Sarcoma                  |                                  X                                       |          1 |
      Leukemia Mononuclear                 |                   X                                   X                 X|          3 |
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Alveolar/Bronchiolar Adenoma         |          X  X                                                            |          2 |
      Alveolar/Bronchiolar Carcinoma       |                                                                          |          1 |
      Histiocytic Sarcoma                  |                X                 X                                       |          2 |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  75                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 7| 6| 6| 6| 7| 6| 5| 6| 6| 5| 4| 4| 7| 6| 5| 7| 7| 6| 7| 4| 7| 5| 6| 5|            |
                             DAY ON TEST   | 0| 3| 5| 8| 0| 3| 1| 5| 1| 2| 2| 9| 8| 3| 2| 5| 1| 3| 2| 0| 5| 3| 8| 5| 6|            |
                                           | 0| 3| 2| 0| 7| 3| 4| 2| 4| 8| 0| 6| 0| 3| 8| 5| 4| 3| 7| 0| 3| 3| 3| 4| 8|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               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|     A      |
    2000 PPM                               | 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|     L      |
                                           | 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                 |                                                                          |            |
                                           |                                                                          |            |
      Leukemia Mononuclear                 | X        X  X     X  X  X  X           X        X  X  X              X  X|         20 |
                                           |__________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                            X                    X     X                  |          4 |
                                           |__________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Eye                                     |                +  +                             +                        |   4        |
      Leukemia Mononuclear                 |                                                 X                        |          1 |
                                           |__________________________________________________________________________|____________|
   Zymbal's Gland                          |                                                 +                        |   1        |
      Carcinoma                            |                                                 X                        |          1 |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Histiocytic Sarcoma                  |                X                                                         |          1 |
      Leukemia Mononuclear                 | X        X  X     X  X  X  X           X        X  X  X              X  X|         19 |
      Renal Tubule, Carcinoma              |                                                                          |          2 |
                                           |__________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                   X                             X                        |          3 |
 __________________________________________________________________________________________________________________________________ 
 SYSTEMIC LESIONS                          |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Multiple Organs                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Histiocytic Sarcoma                  |                X                 X                                       |          2 |
      Leukemia Mononuclear                 | X        X  X     X  X  X  X           X        X  X  X              X  X|         20 |
 __________________________________________________________________________________________________________________________________ 
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  76                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 6| 5| 6| 6| 6| 7| 7| 6| 6| 6| 7| 6| 5| 6| 6| 5| 5| 6| 6| 5| 7| 7| 6| 7|             
                             DAY ON TEST   | 4| 6| 3| 8| 6| 5| 3| 3| 1| 6| 7| 0| 8| 3| 6| 4| 7| 8| 0| 8| 2| 3| 3| 8| 3|             
                                           | 8| 4| 4| 8| 4| 0| 3| 3| 1| 7| 0| 1| 8| 4| 6| 7| 6| 3| 4| 8| 5| 3| 3| 9| 3|             
 __________________________________________|__________________________________________________________________________|             
                                           | 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   | 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6|             
    8000 PPM                               | 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                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +|             
      Leiomyosarcoma                       |                                                                          |             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X  X  X           X     X  X  X  X  X     X  X              X  X  X  X  X|             
                                           |__________________________________________________________________________|             
   Mesentery                               |    +                             +                    +                  |             
                                           |__________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                     X                                X   |             
                                           |__________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Tongue                                  |                                                                          |             
      Hemangiosarcoma                      |                                                                          |             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  77                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 6| 5| 6| 6| 6| 7| 7| 6| 6| 6| 7| 6| 5| 6| 6| 5| 5| 6| 6| 5| 7| 7| 6| 7|             
                             DAY ON TEST   | 4| 6| 3| 8| 6| 5| 3| 3| 1| 6| 7| 0| 8| 3| 6| 4| 7| 8| 0| 8| 2| 3| 3| 8| 3|             
                                           | 8| 4| 4| 8| 4| 0| 3| 3| 1| 7| 0| 1| 8| 4| 6| 7| 6| 3| 4| 8| 5| 3| 3| 9| 3|             
 __________________________________________|__________________________________________________________________________|             
                                           | 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   | 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6|             
    8000 PPM                               | 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 - cont                  |                                                                          |             
                                           |                                                                          |             
                                           |__________________________________________________________________________|             
   Tooth                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |__________________________________________________________________________|             
   Blood Vessel                            |                      +                                                   |             
                                           |__________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |    X                    X     X     X                       X        X   |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |__________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Adenoma                              |                                                    X                     |             
      Leukemia Mononuclear                 | X  X                    X  X  X  X  X     X                          X   |             
                                           |__________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X  X                    X  X  X  X  X     X                          X   |             
      Pheochromocytoma Malignant           |                                                                X         |             
      Pheochromocytoma Benign              |                X     X        X     X                       X  X     X  X|             
      Bilateral, Pheochromocytoma Malignant|                                                                          |             
      Bilateral, Pheochromocytoma Benign   |          X        X        X     X        X  X           X               |             
                                           |__________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Adenoma                              |    X                                         X                       X   |             
      Carcinoma                            |       X     X                    X                                       |             
                                           |__________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                   X     X     X           X                 X        X   |             
      Pars Distalis, Adenoma               | X  X  X  X  X  X  X  X     X           X  X  X  X  X  X  X  X        X  X|             
                                           |__________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                                                          |             
      C-Cell, Adenoma                      | X     X                             X  X                 X           X   |             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  78                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 6| 5| 6| 6| 6| 7| 7| 6| 6| 6| 7| 6| 5| 6| 6| 5| 5| 6| 6| 5| 7| 7| 6| 7|             
                             DAY ON TEST   | 4| 6| 3| 8| 6| 5| 3| 3| 1| 6| 7| 0| 8| 3| 6| 4| 7| 8| 0| 8| 2| 3| 3| 8| 3|             
                                           | 8| 4| 4| 8| 4| 0| 3| 3| 1| 7| 0| 1| 8| 4| 6| 7| 6| 3| 4| 8| 5| 3| 3| 9| 3|             
 __________________________________________|__________________________________________________________________________|             
                                           | 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   | 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6|             
    8000 PPM                               | 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|             
 __________________________________________|__________________________________________________________________________|             
 ENDOCRINE SYSTEM - cont                   |                                                                          |             
                                           |                                                                          |             
      C-Cell, Carcinoma                    |                                                                          |             
      Follicular Cell, Carcinoma           |          X                       X                                       |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |__________________________________________________________________________|             
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Adenoma                              |                                                                          |             
      Carcinoma                            |          X                       X                                       |             
      Leukemia Mononuclear                 |                                                                          |             
                                           |__________________________________________________________________________|             
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Adenoma                              |                                                                          |             
                                           |__________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                     X     X                          X   |             
                                           |__________________________________________________________________________|             
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Bilateral, Interstitial Cell, Adenoma| X              X     X  X           X                          X  X     X|             
      Interstitial Cell, Adenoma           |    X              X           X  X        X  X     X     X               |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |__________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X  X                    X  X  X  X  X     X  X              X        X   |             
                                           |__________________________________________________________________________|             
   Lymph Node                              | +                                +  +                       +     +  +   |             
      Leukemia Mononuclear                 |                                                                          |             
      Iliac, Leukemia Mononuclear          |                                  X                                       |             
      Pancreatic, Leukemia Mononuclear     | X                                   X                       X        X   |             
      Renal, Leukemia Mononuclear          |                                                                   X      |             
                                           |__________________________________________________________________________|             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  79                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 6| 5| 6| 6| 6| 7| 7| 6| 6| 6| 7| 6| 5| 6| 6| 5| 5| 6| 6| 5| 7| 7| 6| 7|             
                             DAY ON TEST   | 4| 6| 3| 8| 6| 5| 3| 3| 1| 6| 7| 0| 8| 3| 6| 4| 7| 8| 0| 8| 2| 3| 3| 8| 3|             
                                           | 8| 4| 4| 8| 4| 0| 3| 3| 1| 7| 0| 1| 8| 4| 6| 7| 6| 3| 4| 8| 5| 3| 3| 9| 3|             
 __________________________________________|__________________________________________________________________________|             
                                           | 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   | 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6|             
    8000 PPM                               | 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|             
 __________________________________________|__________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
   Lymph Node, Bronchial                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X  X  X           X     X  X  X  X  X     X  X              X     X  X  X|             
                                           |__________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X  X              X     X  X  X  X  X     X  X              X     X  X  X|             
                                           |__________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X  X  X                 X  X  X  X  X     X  X              X     X  X  X|             
                                           |__________________________________________________________________________|             
   Lymph Node, Mediastinal                 | +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  M  +  +  +  M  +  +  +|             
      Carcinoma, Metastatic, Thyroid Gland |                                                                          |             
      Leukemia Mononuclear                 | X  X  X           X     X     X  X  X     X  X              X     X  X  X|             
                                           |__________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X  X  X           X     X  X  X  X  X     X  X              X  X  X  X  X|             
                                           |__________________________________________________________________________|             
   Thymus                                  | +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  M  +  +  +  M|             
      Leukemia Mononuclear                 | X                       X     X  X  X     X                       X  X   |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |__________________________________________________________________________|             
   Mammary Gland                           | M  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  M  +  +  M  +  +  +|             
      Fibroadenoma                         |    X                                                                     |             
                                           |__________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Basal Cell Adenoma                   |                                                          X               |             
      Keratoacanthoma                      |                      X                                                   |             
      Squamous Cell Papilloma              |                                                                          |             
      Subcutaneous Tissue, Rhabdomyosarcoma|                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |__________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Skeletal Muscle                         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  80                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 6| 5| 6| 6| 6| 7| 7| 6| 6| 6| 7| 6| 5| 6| 6| 5| 5| 6| 6| 5| 7| 7| 6| 7|             
                             DAY ON TEST   | 4| 6| 3| 8| 6| 5| 3| 3| 1| 6| 7| 0| 8| 3| 6| 4| 7| 8| 0| 8| 2| 3| 3| 8| 3|             
                                           | 8| 4| 4| 8| 4| 0| 3| 3| 1| 7| 0| 1| 8| 4| 6| 7| 6| 3| 4| 8| 5| 3| 3| 9| 3|             
 __________________________________________|__________________________________________________________________________|             
                                           | 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   | 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6|             
    8000 PPM                               | 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|             
 __________________________________________|__________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |__________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                                                      X   |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |__________________________________________________________________________|             
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +|             
                                           |__________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Alveolar/Bronchiolar Carcinoma       |                                                                          |             
      Carcinoma, Metastatic, Thyroid Gland |                                                                          |             
      Leukemia Mononuclear                 | X  X  X           X     X  X  X  X  X     X  X              X  X  X  X  X|             
                                           |__________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |                                                                      X   |             
                                           |__________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |__________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X  X              X     X     X  X  X     X  X              X     X  X  X|             
      Stromal Nephroma                     |                X                                                         |             
      Renal Tubule, Adenoma                |                      X                                                   |             
                                           |__________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 |    X                          X     X     X                          X   |             
 __________________________________________|__________________________________________________________________________|             
 SYSTEMIC LESIONS                          |                                                                          |             
                                            __________________________________________________________________________|             
   Multiple Organs                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Leukemia Mononuclear                 | X  X  X           X     X  X  X  X  X     X  X              X  X  X  X  X|             
 __________________________________________|__________________________________________________________________________|             
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  81                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 5| 6| 6| 6| 6| 6| 7| 7| 6| 6| 7| 6| 4| 7| 7| 6| 7| 6| 5| 6| 6| 6| 6| 7|            |
                             DAY ON TEST   | 6| 4| 0| 7| 6| 1| 5| 3| 3| 3| 9| 0| 3| 9| 3| 0| 1| 2| 5| 0| 0| 9| 0| 3| 0|            |
                                           | 0| 0| 8| 8| 4| 0| 8| 3| 3| 1| 0| 1| 6| 0| 3| 2| 8| 0| 0| 5| 7| 2| 4| 6| 0|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               ANIMAL ID   | 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6|     A      |
    8000 PPM                               | 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|     L      |
                                           | 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                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |                                                          X               |          1 |
                                           |__________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                           |__________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |       X                                                  X               |          2 |
                                           |__________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                           |__________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                           |__________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leiomyosarcoma                       |                                                    X                     |          1 |
      Leukemia Mononuclear                 |                                                          X               |          1 |
                                           |__________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |    X  X  X           X  X  X  X  X  X     X  X           X     X  X      |         30 |
                                           |__________________________________________________________________________|____________|
   Mesentery                               |       +           +           +     +     +        +           +        +|  11        |
                                           |__________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                                          X               |          3 |
                                           |__________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                                          X               |          1 |
                                           |__________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  82                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 5| 6| 6| 6| 6| 6| 7| 7| 6| 6| 7| 6| 4| 7| 7| 6| 7| 6| 5| 6| 6| 6| 6| 7|            |
                             DAY ON TEST   | 6| 4| 0| 7| 6| 1| 5| 3| 3| 3| 9| 0| 3| 9| 3| 0| 1| 2| 5| 0| 0| 9| 0| 3| 0|            |
                                           | 0| 0| 8| 8| 4| 0| 8| 3| 3| 1| 0| 1| 6| 0| 3| 2| 8| 0| 0| 5| 7| 2| 4| 6| 0|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               ANIMAL ID   | 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6|     A      |
    8000 PPM                               | 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|     L      |
                                           | 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 - cont                  |                                                                          |            |
                                           |                                                                          |            |
      Leukemia Mononuclear                 |                                                                   X      |          1 |
                                           |__________________________________________________________________________|____________|
   Tongue                                  |                   +                                                      |   1        |
      Hemangiosarcoma                      |                   X                                                      |          1 |
                                           |__________________________________________________________________________|____________|
   Tooth                                   |                                              +                           |   1        |
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Blood Vessel                            |                                                                         +|   2        |
                                           |__________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |          X           X           X           X           X        X      |         12 |
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Adenoma                              |                                                                          |          1 |
      Leukemia Mononuclear                 |       X  X           X  X  X     X        X  X           X     X  X      |         20 |
                                           |__________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |       X  X           X  X  X     X        X  X           X     X  X      |         20 |
      Pheochromocytoma Malignant           |                            X                                             |          2 |
      Pheochromocytoma Benign              | X     X                    X                                             |         11 |
      Bilateral, Pheochromocytoma Malignant|                               X                                          |          1 |
      Bilateral, Pheochromocytoma Benign   |                      X  X           X              X                    X|         12 |
                                           |__________________________________________________________________________|____________|
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Adenoma                              |                                                 X                        |          4 |
      Carcinoma                            |                                                                         X|          4 |
                                           |__________________________________________________________________________|____________|
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +|  47        |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  83                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 5| 6| 6| 6| 6| 6| 7| 7| 6| 6| 7| 6| 4| 7| 7| 6| 7| 6| 5| 6| 6| 6| 6| 7|            |
                             DAY ON TEST   | 6| 4| 0| 7| 6| 1| 5| 3| 3| 3| 9| 0| 3| 9| 3| 0| 1| 2| 5| 0| 0| 9| 0| 3| 0|            |
                                           | 0| 0| 8| 8| 4| 0| 8| 3| 3| 1| 0| 1| 6| 0| 3| 2| 8| 0| 0| 5| 7| 2| 4| 6| 0|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               ANIMAL ID   | 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6|     A      |
    8000 PPM                               | 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|     L      |
                                           | 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|            |
 _____________________________________________________________________________________________________________________|____________|
 ENDOCRINE SYSTEM - cont                   |                                                                          |            |
                                           |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |          X           X        X  X        X  X           X        X      |         14 |
      Pars Distalis, Adenoma               | X  X  X     X  X  X  X  X     X  X  X  X  X  X  X  X  X  X  X  X     X  X|         41 |
                                           |__________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                                          X               |          1 |
      C-Cell, Adenoma                      |                                                                      X   |          7 |
      C-Cell, Carcinoma                    |                                                             X            |          1 |
      Follicular Cell, Carcinoma           |                                                 X     X                 X|          5 |
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Adenoma                              |                                                                         X|          1 |
      Carcinoma                            |    X                                                                     |          3 |
      Leukemia Mononuclear                 |                                                          X               |          1 |
                                           |__________________________________________________________________________|____________|
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Adenoma                              |             X                                                            |          1 |
                                           |__________________________________________________________________________|____________|
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                      X                                   X               |          5 |
                                           |__________________________________________________________________________|____________|
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Bilateral, Interstitial Cell, Adenoma|             X     X  X     X                       X              X      |         14 |
      Interstitial Cell, Adenoma           |                                                 X              X        X|         11 |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  84                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 5| 6| 6| 6| 6| 6| 7| 7| 6| 6| 7| 6| 4| 7| 7| 6| 7| 6| 5| 6| 6| 6| 6| 7|            |
                             DAY ON TEST   | 6| 4| 0| 7| 6| 1| 5| 3| 3| 3| 9| 0| 3| 9| 3| 0| 1| 2| 5| 0| 0| 9| 0| 3| 0|            |
                                           | 0| 0| 8| 8| 4| 0| 8| 3| 3| 1| 0| 1| 6| 0| 3| 2| 8| 0| 0| 5| 7| 2| 4| 6| 0|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               ANIMAL ID   | 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6|     A      |
    8000 PPM                               | 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|     L      |
                                           | 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                      |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |       X  X           X  X  X  X  X        X  X           X     X  X      |         23 |
                                           |__________________________________________________________________________|____________|
   Lymph Node                              |       +                    +     +                       +               |  10        |
      Leukemia Mononuclear                 |                                  X                                       |          1 |
      Iliac, Leukemia Mononuclear          |       X                                                  X               |          3 |
      Pancreatic, Leukemia Mononuclear     |                                  X                       X               |          6 |
      Renal, Leukemia Mononuclear          |       X                    X                             X               |          4 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Bronchial                   | M  M  +  +  M  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +|  45        |
      Leukemia Mononuclear                 |       X  X           X  X  X  X  X  X     X  X           X     X  X      |         28 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |       X  X           X  X  X  X  X  X     X  X           X     X  X      |         27 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |       X  X           X  X  X  X  X  X     X  X           X     X  X      |         27 |
                                           |__________________________________________________________________________|____________|
   Lymph Node, Mediastinal                 | +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +|  45        |
      Carcinoma, Metastatic, Thyroid Gland |                                                       X                  |          1 |
      Leukemia Mononuclear                 |       X  X           X  X  X  X  X        X  X           X     X  X      |         26 |
                                           |__________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |    X  X  X     X     X  X  X  X  X  X     X  X           X     X  X      |         31 |
                                           |__________________________________________________________________________|____________|
   Thymus                                  | M  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  M  +  +  +  +  +|  42        |
      Leukemia Mononuclear                 |                      X     X  X           X  X                 X  X      |         15 |
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Mammary Gland                           | +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +|  44        |
      Fibroadenoma                         |                                                                          |          1 |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                             Page  85                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 5| 6| 6| 6| 6| 6| 7| 7| 6| 6| 7| 6| 4| 7| 7| 6| 7| 6| 5| 6| 6| 6| 6| 7|            |
                             DAY ON TEST   | 6| 4| 0| 7| 6| 1| 5| 3| 3| 3| 9| 0| 3| 9| 3| 0| 1| 2| 5| 0| 0| 9| 0| 3| 0|            |
                                           | 0| 0| 8| 8| 4| 0| 8| 3| 3| 1| 0| 1| 6| 0| 3| 2| 8| 0| 0| 5| 7| 2| 4| 6| 0|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               ANIMAL ID   | 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6|     A      |
    8000 PPM                               | 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|     L      |
                                           | 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               |                                                                          |            |
                                           |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Basal Cell Adenoma                   |                               X                                          |          2 |
      Keratoacanthoma                      |                      X                       X                          X|          4 |
      Squamous Cell Papilloma              |                         X                                                |          1 |
      Subcutaneous Tissue, Rhabdomyosarcoma|                                                                         X|          1 |
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                           |__________________________________________________________________________|____________|
   Skeletal Muscle                         |                                                                         +|   1        |
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                                                          X        X      |          3 |
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Larynx                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                           |__________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Alveolar/Bronchiolar Carcinoma       |                                           X                              |          1 |
      Carcinoma, Metastatic, Thyroid Gland |                                                       X                  |          1 |
      Leukemia Mononuclear                 |    X  X  X           X  X  X  X  X  X     X  X           X     X  X      |         30 |
                                           |__________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Leukemia Mononuclear                 |                                                          X     X         |          3 |
                                           |__________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|____________|
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                             Page  86                                                               
                                                                                                                                   
NTP Experiment-Test: 88070-03                        NEOPLASMS BY INDIVIDUAL ANIMAL                               Report: PEIRPT04  
Study Type: CHRONIC                                             ISOBUTENE                                         Date: 09/14/00    
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 13:40:24    
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 5| 6| 6| 6| 6| 6| 7| 7| 6| 6| 7| 6| 4| 7| 7| 6| 7| 6| 5| 6| 6| 6| 6| 7|            |
                             DAY ON TEST   | 6| 4| 0| 7| 6| 1| 5| 3| 3| 3| 9| 0| 3| 9| 3| 0| 1| 2| 5| 0| 0| 9| 0| 3| 0|            |
                                           | 0| 0| 8| 8| 4| 0| 8| 3| 3| 1| 0| 1| 6| 0| 3| 2| 8| 0| 0| 5| 7| 2| 4| 6| 0|            |
 __________________________________________|__________________________________________________________________________|     T (*)  |
                                           | 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|     O      |
   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|     T      |
                               ANIMAL ID   | 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6|     A      |
    8000 PPM                               | 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|     L      |
                                           | 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|            |
 _____________________________________________________________________________________________________________________|____________|
 URINARY SYSTEM                            |                                                                          |            |
                                           |__________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |    X  X  X           X  X  X  X  X        X  X           X     X  X      |         26 |
      Stromal Nephroma                     |                                                                          |          1 |
      Renal Tubule, Adenoma                |                X                                                         |          2 |
                                           |__________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |                      X                                   X        X      |          8 |
 __________________________________________________________________________________________________________________________________ 
 SYSTEMIC LESIONS                          |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Multiple Organs                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Leukemia Mononuclear                 |    X  X  X     X     X  X  X  X  X  X     X  X           X     X  X      |         31 |
 __________________________________________________________________________________________________________________________________ 
                                                                                                                                    
                         * : Total animals with tissue examined microscopically; total animals with tumor                           
                         + : Tissue examined microscopically                      M : Missing tissue                                
                         X : Lesion present                                       A : Autolysis precludes evaluation                
                         I : Insufficient tissue                              BLANK : Not examined microscopically                  
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page  87                                                               
                                                                                                                                   
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