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TDMS Study 05158-03 Pathology Tables

NTP Experiment-Test: 05158-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                        MOLYBDENUM TRIOXIDE                                    Date: 04/04/96
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 01:54:06




       Facility:  Battelle Northwest

       Chemical CAS #:  0001313-27-5

       Lock Date:  08/06/93

       Cage Range:  All

       Reasons For Removal:    All

       Removal Date Range:     All

       Treatment Groups:       Include All




































a  Number of animals examined microscopically at site and number of animals with lesion

                                                              Page   1


NTP Experiment-Test: 05158-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                        MOLYBDENUM TRIOXIDE                                    Date: 04/04/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 01:54:06  
____________________________________________________________________________________________________________________________________

         FISCHER 344 RATS FEMALE                   CONTROL      10 MG/M3     30 MG/M3     100                                       
                                                                                          MG/M3                                     
____________________________________________________________________________________________________________________________________

DISPOSITION SUMMARY                                                                                                                 

  Animals Initially In Study                          50           50           50           50                                     
  Early Deaths                                                                                                                      
    Moribund Sacrifice                                18           25           23           23                                     
    Natural Death                                      4            1            3            4                                     
  Survivors                                                                                                                         
    Moribund Sacrifice                                                                        1                                     
    Terminal Sacrifice                                28           24           24           22                                     

  Animals Examined Microscopically                    50           50           50           50                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Intestine Large, Colon                             (49)         (49)         (48)         (48)                                   
      Necrosis                                                      1 (2%)                                                          
   Intestine Large, Rectum                            (49)         (50)         (46)         (50)                                   
      Mineralization                                                                          1 (2%)                                
   Intestine Large, Cecum                             (49)         (49)         (47)         (48)                                   
      Mineralization                                   1 (2%)                                 3 (6%)                                
   Intestine Small, Duodenum                          (49)         (49)         (48)         (49)                                   
      Inflammation, Acute                                                                     1 (2%)                                
   Intestine Small, Ileum                             (48)         (49)         (47)         (48)                                   
      Inflammation, Chronic Active                                               1 (2%)                                             
   Liver                                              (50)         (49)         (50)         (50)                                   
      Angiectasis                                      3 (6%)       1 (2%)       4 (8%)       3 (6%)                                
      Basophilic Focus                                43 (86%)     44 (90%)     43 (86%)     39 (78%)                               
      Clear Cell Focus                                 7 (14%)      5 (10%)     11 (22%)      7 (14%)                               
      Degeneration, Cystic                                                                    1 (2%)                                
      Degeneration, Fatty                             18 (36%)     18 (37%)     13 (26%)     18 (36%)                               
      Eosinophilic Focus                               5 (10%)      1 (2%)       2 (4%)       4 (8%)                                
      Hematopoietic Cell Proliferation                 2 (4%)                    1 (2%)                                             
      Hepatodiaphragmatic Nodule                       5 (10%)     10 (20%)      9 (18%)      9 (18%)                               
      Mixed Cell Focus                                 9 (18%)      9 (18%)      6 (12%)     12 (24%)                               
      Necrosis                                         2 (4%)       1 (2%)       1 (2%)       1 (2%)                                
      Thrombosis                                                    1 (2%)                                                          
      Vacuolization Cytoplasmic, Focal                 3 (6%)       2 (4%)                    4 (8%)                                
      Bile Duct, Hyperplasia                          15 (30%)     11 (22%)     12 (24%)     10 (20%)                               
      Centrilobular, Necrosis                          5 (10%)      7 (14%)      2 (4%)       4 (8%)                                
   Mesentery                                          (3)          (11)         (5)          (8)                                    
      Artery, Inflammation, Chronic Active                                       1 (20%)                                            
      Fat, Necrosis                                    2 (67%)     11 (100%)     4 (80%)      8 (100%)                              
   Pancreas                                           (49)         (49)         (50)         (50)                                   
      Atrophy                                         21 (43%)     11 (22%)     15 (30%)     18 (36%)                               
      Basophilic Focus                                 2 (4%)       1 (2%)       2 (4%)       1 (2%)                                
      Hyperplasia                                                   1 (2%)       1 (2%)       3 (6%)                                
      Artery, Inflammation                                                       1 (2%)       1 (2%)                                

a  Number of animals examined microscopically at site and number of animals with lesion                                             

                                                             Page    2                                                              
NTP Experiment-Test: 05158-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                        MOLYBDENUM TRIOXIDE                                    Date: 04/04/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 01:54:06  
____________________________________________________________________________________________________________________________________

         FISCHER 344 RATS FEMALE                   CONTROL      10 MG/M3     30 MG/M3     100                                       
                                                                                          MG/M3                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ALIMENTARY SYSTEM - CONT                                                                                                            
   Salivary Glands                                    (50)         (50)         (50)         (50)                                   
      Atrophy                                          1 (2%)       1 (2%)       2 (4%)                                             
   Stomach, Forestomach                               (50)         (49)         (50)         (50)                                   
      Hyperplasia, Squamous                                         2 (4%)       1 (2%)       2 (4%)                                
      Mineralization                                   1 (2%)       1 (2%)       1 (2%)       5 (10%)                               
      Necrosis                                         3 (6%)       5 (10%)      2 (4%)       8 (16%)                               
   Stomach, Glandular                                 (49)         (49)         (50)         (50)                                   
      Inflammation, Chronic Active                                               1 (2%)                                             
      Mineralization                                   7 (14%)     11 (22%)      8 (16%)      6 (12%)                               
      Necrosis                                                      2 (4%)       3 (6%)       1 (2%)                                
   Tooth                                              (1)                                                                           
      Developmental Malformation                       1 (100%)                                                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Heart                                              (50)         (50)         (50)         (50)                                   
      Cardiomyopathy                                  41 (82%)     41 (82%)     43 (86%)     46 (92%)                               
      Artery, Thrombosis                                                                      1 (2%)                                
      Atrium, Thrombosis                                                                      2 (4%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Cortex                                     (49)         (49)         (50)         (50)                                   
      Degeneration, Cystic                                          2 (4%)       2 (4%)       1 (2%)                                
      Hyperplasia                                     21 (43%)     23 (47%)     26 (52%)     25 (50%)                               
      Hypertrophy                                      9 (18%)     10 (20%)      8 (16%)      8 (16%)                               
      Necrosis                                         1 (2%)       3 (6%)                    1 (2%)                                
      Vacuolization Cytoplasmic                        6 (12%)      6 (12%)      4 (8%)       4 (8%)                                
   Adrenal Medulla                                    (49)         (49)         (50)         (50)                                   
      Hyperplasia                                      9 (18%)     12 (24%)     12 (24%)      7 (14%)                               
   Islets, Pancreatic                                 (49)         (49)         (50)         (50)                                   
      Hyperplasia                                                   2 (4%)                                                          
   Parathyroid Gland                                  (50)         (49)         (48)         (48)                                   
      Hyperplasia                                      1 (2%)       2 (4%)       1 (2%)       2 (4%)                                
   Pituitary Gland                                    (49)         (50)         (50)         (50)                                   
      Pars Distalis, Cyst                                           1 (2%)       1 (2%)       1 (2%)                                
      Pars Distalis, Hyperplasia                       3 (6%)       9 (18%)      9 (18%)      8 (16%)                               
   Thyroid Gland                                      (49)         (49)         (50)         (50)                                   
      Bilateral, C-Cell, Hyperplasia                   1 (2%)                                                                       
      C-Cell, Hyperplasia                             41 (84%)     37 (76%)     42 (84%)     41 (82%)                               
      Follicular Cell, Hyperplasia                                                            1 (2%)                                
____________________________________________________________________________________________________________________________________

a  Number of animals examined microscopically at site and number of animals with lesion                                             

                                                             Page    3                                                              
NTP Experiment-Test: 05158-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                        MOLYBDENUM TRIOXIDE                                    Date: 04/04/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 01:54:06  
____________________________________________________________________________________________________________________________________

         FISCHER 344 RATS FEMALE                   CONTROL      10 MG/M3     30 MG/M3     100                                       
                                                                                          MG/M3                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Clitoral Gland                                     (44)         (48)         (47)         (47)                                   
      Cyst                                                                                    1 (2%)                                
      Hyperplasia                                                   2 (4%)       1 (2%)                                             
      Inflammation, Chronic Active                     2 (5%)       6 (13%)      4 (9%)       3 (6%)                                
      Duct, Hyperplasia, Squamous                                   2 (4%)                                                          
   Ovary                                              (50)         (50)         (50)         (50)                                   
      Cyst                                             3 (6%)       6 (12%)      7 (14%)      7 (14%)                               
      Hyperplasia, Tubular                                                       1 (2%)                                             
   Uterus                                             (50)         (49)         (50)         (50)                                   
      Hydrometra                                       2 (4%)                                                                       
      Endometrium, Hyperplasia                                      1 (2%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Lymph Node                                         (3)          (8)          (2)          (2)                                    
      Pancreatic, Hemorrhage                                                     1 (50%)                                            
      Pancreatic, Pigmentation                                      1 (13%)                                                         
      Renal, Ectasia                                                             1 (50%)                                            
      Renal, Hemorrhage                                             1 (13%)                                                         
   Lymph Node, Mandibular                             (46)         (41)         (47)         (43)                                   
      Infiltration Cellular, Plasma Cell               1 (2%)       1 (2%)                                                          
   Lymph Node, Mediastinal                            (41)         (41)         (43)         (48)                                   
      Hemorrhage                                                    1 (2%)                                                          
   Spleen                                             (49)         (49)         (50)         (50)                                   
      Accessory Spleen                                 1 (2%)                                                                       
      Fibrosis                                                      3 (6%)       5 (10%)      2 (4%)                                
      Hematopoietic Cell Proliferation                 4 (8%)       2 (4%)       6 (12%)      2 (4%)                                
      Hemorrhage                                       1 (2%)       2 (4%)       1 (2%)       1 (2%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Mammary Gland                                      (50)         (50)         (49)         (50)                                   
      Galactocele                                                   1 (2%)                                                          
      Hyperplasia, Atypical                            1 (2%)       1 (2%)       1 (2%)                                             
      Inflammation, Chronic Active                                  1 (2%)                                                          
   Skin                                               (50)         (49)         (50)         (50)                                   
      Hyperkeratosis                                   1 (2%)       1 (2%)                                                          
      Inflammation, Chronic Active                     2 (4%)       2 (4%)       2 (4%)                                             

a  Number of animals examined microscopically at site and number of animals with lesion                                             

                                                             Page    4                                                              
NTP Experiment-Test: 05158-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                        MOLYBDENUM TRIOXIDE                                    Date: 04/04/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 01:54:06  
____________________________________________________________________________________________________________________________________

         FISCHER 344 RATS FEMALE                   CONTROL      10 MG/M3     30 MG/M3     100                                       
                                                                                          MG/M3                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
INTEGUMENTARY SYSTEM - CONT                                                                                                         
      Subcutaneous Tissue, Angiectasis                                                        1 (2%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   Bone                                               (50)         (50)         (50)         (50)                                   
      Fibrous Osteodystrophy                                        1 (2%)       1 (2%)                                             
      Hyperostosis                                     4 (8%)       4 (8%)       1 (2%)       9 (18%)                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (50)         (50)         (50)         (50)                                   
      Thrombosis                                                    1 (2%)                                                          
      Meninges, Hyperplasia                                         1 (2%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Larynx                                             (49)         (49)         (49)         (50)                                   
      Epiglottis, Hyperplasia                          3 (6%)      10 (20%)      5 (10%)      1 (2%)                                
      Epiglottis, Metaplasia, Squamous                             18 (37%)     29 (59%)     49 (98%)                               
   Lung                                               (50)         (50)         (50)         (50)                                   
      Metaplasia, Focal                                             1 (2%)                                                          
      Metaplasia, Squamous                                          1 (2%)                                                          
      Alveolar Epithelium, Hyperplasia                 7 (14%)     10 (20%)     12 (24%)      7 (14%)                               
      Alveolus, Infiltration Cellular, Histiocyte                   1 (2%)                                                          
      Alveolus, Inflammation, Chronic                 14 (28%)     13 (26%)     43 (86%)     49 (98%)                               
      Bronchiole, Hyperplasia                          1 (2%)                                                                       
      Mediastinum, Thrombosis                                                                 1 (2%)                                
   Nose                                               (48)         (49)         (50)         (50)                                   
      Inflammation, Suppurative                        7 (15%)      2 (4%)       6 (12%)      2 (4%)                                
      Thrombosis                                       4 (8%)       5 (10%)      1 (2%)       4 (8%)                                
      Olfactory Epithelium, Degeneration, Hyaline     39 (81%)     47 (96%)     50 (100%)    50 (100%)                              
      Olfactory Epithelium, Metaplasia, Focal                       1 (2%)                                                          
      Respiratory Epithelium, Degeneration, Hyaline    1 (2%)      13 (27%)     50 (100%)    50 (100%)                              
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   Eye                                                (1)          (6)          (1)          (2)                                    
      Cataract                                                      1 (17%)      1 (100%)                                           
      Degeneration                                     1 (100%)     4 (67%)                   2 (100%)                              
____________________________________________________________________________________________________________________________________
                                                                                                                                    

a  Number of animals examined microscopically at site and number of animals with lesion                                             

                                                             Page    5                                                              
NTP Experiment-Test: 05158-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                        MOLYBDENUM TRIOXIDE                                    Date: 04/04/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 01:54:06  
____________________________________________________________________________________________________________________________________

         FISCHER 344 RATS FEMALE                   CONTROL      10 MG/M3     30 MG/M3     100                                       
                                                                                          MG/M3                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (50)         (49)         (50)         (50)                                   
      Cyst                                                          1 (2%)       1 (2%)                                             
      Infarct                                          1 (2%)                                                                       
      Nephropathy                                     48 (96%)     47 (96%)     47 (94%)     50 (100%)                              
      Renal Tubule, Hyperplasia                        1 (2%)       3 (6%)       2 (4%)       1 (2%)                                
      Transitional Epithelium, Mineralization                       1 (2%)                                                          
   Urinary Bladder                                    (49)         (50)         (50)         (50)                                   
      Transitional Epithelium, Hyperplasia                          1 (2%)                    1 (2%)                                
                                                                                                                                    

a  Number of animals examined microscopically at site and number of animals with lesion                                             

                                                             Page    6                                                              
NTP Experiment-Test: 05158-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                        MOLYBDENUM TRIOXIDE                                    Date: 04/04/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 01:54:06  
____________________________________________________________________________________________________________________________________

         FISCHER 344 RATS MALE                     CONTROL      10 MG/M3     30 MG/M3     100                                       
                                                                                          MG/M3                                     
____________________________________________________________________________________________________________________________________

DISPOSITION SUMMARY                                                                                                                 

  Animals Initially In Study                          50           50           50           50                                     
  Early Deaths                                                                                                                      
    Natural Death                                      4            5            3            5                                     
    Moribund Sacrifice                                29           35           31           28                                     
  Survivors                                                                                                                         
    Terminal Sacrifice                                16           10           16           17                                     
    Moribund Sacrifice                                 1                                                                            

  Animals Examined Microscopically                    50           50           50           50                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Intestine Large, Colon                             (49)         (46)         (50)         (50)                                   
      Mineralization                                                1 (2%)                                                          
   Intestine Large, Cecum                             (48)         (47)         (48)         (49)                                   
      Hemorrhage                                                                              1 (2%)                                
      Infiltration Cellular, Mixed Cell                                          1 (2%)                                             
      Mineralization                                   1 (2%)                    1 (2%)       1 (2%)                                
      Necrosis                                                                   1 (2%)                                             
   Intestine Small, Duodenum                          (49)         (48)         (49)         (49)                                   
      Mineralization                                                1 (2%)                                                          
      Necrosis                                                                                2 (4%)                                
   Intestine Small, Ileum                             (48)         (47)         (46)         (49)                                   
      Inflammation, Chronic Active                                  1 (2%)                                                          
      Mineralization                                                1 (2%)                                                          
   Liver                                              (50)         (50)         (50)         (50)                                   
      Angiectasis                                      3 (6%)       6 (12%)      1 (2%)       2 (4%)                                
      Basophilic Focus                                21 (42%)     21 (42%)     23 (46%)     21 (42%)                               
      Clear Cell Focus                                 5 (10%)      4 (8%)       7 (14%)      3 (6%)                                
      Cyst                                                          1 (2%)                                                          
      Degeneration, Cystic                            17 (34%)     16 (32%)     16 (32%)     24 (48%)                               
      Degeneration, Fatty                             15 (30%)     15 (30%)     17 (34%)     14 (28%)                               
      Eosinophilic Focus                               4 (8%)       8 (16%)      7 (14%)     10 (20%)                               
      Hematopoietic Cell Proliferation                              1 (2%)                                                          
      Hepatodiaphragmatic Nodule                       1 (2%)                    5 (10%)      4 (8%)                                
      Mixed Cell Focus                                 5 (10%)      3 (6%)       3 (6%)       5 (10%)                               
      Necrosis                                                                                1 (2%)                                
      Vacuolization Cytoplasmic, Focal                 2 (4%)       1 (2%)                                                          
      Bile Duct, Hyperplasia                          46 (92%)     35 (70%)     40 (80%)     39 (78%)                               
      Centrilobular, Necrosis                         14 (28%)     11 (22%)     12 (24%)     10 (20%)                               
   Mesentery                                          (10)         (9)          (9)          (11)                                   
      Inflammation, Acute                                           1 (11%)                                                         
      Artery, Mineralization                                        1 (11%)                                                         
      Fat, Hemorrhage                                               1 (11%)                                                         
      Fat, Necrosis                                    9 (90%)      6 (67%)      9 (100%)    10 (91%)                               

a  Number of animals examined microscopically at site and number of animals with lesion                                             

                                                             Page    7                                                              
NTP Experiment-Test: 05158-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                        MOLYBDENUM TRIOXIDE                                    Date: 04/04/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 01:54:06  
____________________________________________________________________________________________________________________________________

         FISCHER 344 RATS MALE                     CONTROL      10 MG/M3     30 MG/M3     100                                       
                                                                                          MG/M3                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ALIMENTARY SYSTEM - CONT                                                                                                            
   Pancreas                                           (50)         (50)         (50)         (50)                                   
      Atrophy                                         32 (64%)     28 (56%)     24 (48%)     34 (68%)                               
      Basophilic Focus                                 1 (2%)                                 2 (4%)                                
      Hyperplasia                                      6 (12%)      2 (4%)       2 (4%)       5 (10%)                               
      Thrombosis                                                                              1 (2%)                                
      Artery, Inflammation                                                                    1 (2%)                                
   Salivary Glands                                    (50)         (50)         (50)         (50)                                   
      Atrophy                                          2 (4%)                                 3 (6%)                                
      Artery, Mineralization                                        1 (2%)                                                          
   Stomach, Forestomach                               (50)         (50)         (50)         (50)                                   
      Hyperplasia, Squamous                                                      2 (4%)       2 (4%)                                
      Inflammation, Acute                                           1 (2%)                                                          
      Mineralization                                   3 (6%)       4 (8%)       4 (8%)       1 (2%)                                
      Necrosis                                        11 (22%)      4 (8%)       7 (14%)      4 (8%)                                
   Stomach, Glandular                                 (50)         (50)         (50)         (50)                                   
      Mineralization                                   5 (10%)      7 (14%)      5 (10%)     10 (20%)                               
      Necrosis                                         7 (14%)      6 (12%)      4 (8%)       2 (4%)                                
   Tooth                                                           (2)          (1)                                                 
      Developmental Malformation                                    1 (50%)                                                         
      Inflammation, Chronic Active                                  1 (50%)      1 (100%)                                           
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Blood Vessel                                       (1)          (2)          (1)          (2)                                    
      Aorta, Mineralization                            1 (100%)     2 (100%)     1 (100%)     2 (100%)                              
   Heart                                              (50)         (50)         (50)         (50)                                   
      Cardiomyopathy                                  44 (88%)     38 (76%)     40 (80%)     45 (90%)                               
      Artery, Mineralization                           1 (2%)       2 (4%)       1 (2%)       3 (6%)                                
      Atrium, Thrombosis                               5 (10%)      7 (14%)      6 (12%)      4 (8%)                                
      Endocardium, Hyperplasia                                                   1 (2%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Cortex                                     (50)         (50)         (50)         (50)                                   
      Atrophy                                                                    1 (2%)       1 (2%)                                
      Hyperplasia                                     35 (70%)     19 (38%)     26 (52%)     26 (52%)                               
      Hypertrophy                                      5 (10%)      6 (12%)      8 (16%)      8 (16%)                               
      Necrosis                                         1 (2%)       1 (2%)                    1 (2%)                                
      Thrombosis                                                                 1 (2%)                                             
      Vacuolization Cytoplasmic                        4 (8%)       2 (4%)       2 (4%)       2 (4%)                                
   Adrenal Medulla                                    (50)         (50)         (50)         (50)                                   
      Hyperplasia                                     31 (62%)     25 (50%)     27 (54%)     25 (50%)                               
      Bilateral, Hyperplasia                           1 (2%)       2 (4%)       1 (2%)       4 (8%)                                
   Islets, Pancreatic                                 (50)         (50)         (49)         (49)                                   
      Hyperplasia                                                   3 (6%)                    1 (2%)                                

a  Number of animals examined microscopically at site and number of animals with lesion                                             

                                                             Page    8                                                              
NTP Experiment-Test: 05158-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                        MOLYBDENUM TRIOXIDE                                    Date: 04/04/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 01:54:06  
____________________________________________________________________________________________________________________________________

         FISCHER 344 RATS MALE                     CONTROL      10 MG/M3     30 MG/M3     100                                       
                                                                                          MG/M3                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ENDOCRINE SYSTEM - CONT                                                                                                             
   Parathyroid Gland                                  (47)         (49)         (46)         (49)                                   
      Hyperplasia                                     11 (23%)      9 (18%)     10 (22%)     14 (29%)                               
   Pituitary Gland                                    (49)         (50)         (50)         (48)                                   
      Pars Distalis, Hyperplasia                       7 (14%)      7 (14%)      6 (12%)      6 (13%)                               
   Thyroid Gland                                      (50)         (50)         (50)         (50)                                   
      C-Cell, Hyperplasia                             35 (70%)     29 (58%)     31 (62%)     30 (60%)                               
      Follicular Cell, Hyperplasia                     2 (4%)                                 4 (8%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Epididymis                                         (50)         (50)         (50)         (50)                                   
      Granuloma Sperm                                  1 (2%)       1 (2%)                    1 (2%)                                
   Penis                                                                        (2)                                                 
      Inflammation, Acute                                                        1 (50%)                                            
   Preputial Gland                                    (50)         (50)         (50)         (50)                                   
      Cyst                                                                                    1 (2%)                                
      Hyperplasia                                                                             1 (2%)                                
      Inflammation, Chronic Active                     1 (2%)       4 (8%)       3 (6%)       3 (6%)                                
   Prostate                                           (50)         (50)         (50)         (50)                                   
      Hyperplasia                                      6 (12%)      6 (12%)     12 (24%)      7 (14%)                               
      Inflammation, Chronic Active                     4 (8%)       5 (10%)      2 (4%)       5 (10%)                               
   Seminal Vesicle                                    (50)         (50)         (50)         (50)                                   
      Inflammation, Chronic Active                     1 (2%)                                                                       
      Mineralization                                                1 (2%)                                                          
   Testes                                             (50)         (50)         (50)         (50)                                   
      Atrophy                                          6 (12%)      4 (8%)       3 (6%)       2 (4%)                                
      Artery, Inflammation, Chronic Active             2 (4%)       4 (8%)       2 (4%)       2 (4%)                                
      Interstitial Cell, Hyperplasia                   7 (14%)      7 (14%)      7 (14%)      5 (10%)                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Bone Marrow                                        (50)         (50)         (50)         (50)                                   
      Atrophy                                                                                 1 (2%)                                
      Myelofibrosis                                                 1 (2%)                                                          
      Necrosis                                                      1 (2%)                                                          
   Lymph Node                                         (16)         (17)         (8)          (15)                                   
      Iliac, Ectasia                                                1 (6%)                                                          
      Iliac, Infiltration Cellular, Plasma Cell                                               1 (7%)                                
      Renal, Hemorrhage                                3 (19%)      1 (6%)       1 (13%)                                            
      Renal, Infiltration Cellular, Plasma Cell                                               1 (7%)                                

a  Number of animals examined microscopically at site and number of animals with lesion                                             

                                                             Page    9                                                              
NTP Experiment-Test: 05158-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                        MOLYBDENUM TRIOXIDE                                    Date: 04/04/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 01:54:06  
____________________________________________________________________________________________________________________________________

         FISCHER 344 RATS MALE                     CONTROL      10 MG/M3     30 MG/M3     100                                       
                                                                                          MG/M3                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
HEMATOPOIETIC SYSTEM - CONT                                                                                                         
   Lymph Node, Mandibular                             (48)         (48)         (49)         (48)                                   
      Infiltration Cellular, Plasma Cell               1 (2%)       3 (6%)       1 (2%)       2 (4%)                                
   Lymph Node, Mesenteric                             (50)         (50)         (50)         (49)                                   
      Ectasia                                                       2 (4%)                                                          
   Lymph Node, Mediastinal                            (48)         (49)         (46)         (48)                                   
      Hemorrhage                                       1 (2%)       1 (2%)                    1 (2%)                                
   Spleen                                             (50)         (50)         (50)         (50)                                   
      Accessory Spleen                                              1 (2%)                    1 (2%)                                
      Atrophy                                                                                 2 (4%)                                
      Fibrosis                                        15 (30%)     13 (26%)     15 (30%)     17 (34%)                               
      Hematopoietic Cell Proliferation                              1 (2%)       1 (2%)                                             
      Hemorrhage                                                    2 (4%)                    1 (2%)                                
      Necrosis                                         1 (2%)       2 (4%)       2 (4%)       1 (2%)                                
      Thrombosis                                                                              1 (2%)                                
   Thymus                                             (45)         (45)         (44)         (44)                                   
      Atrophy                                                                                 1 (2%)                                
      Cyst                                             1 (2%)                                                                       
      Hemorrhage                                                    1 (2%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Mammary Gland                                      (30)         (25)         (25)         (27)                                   
      Galactocele                                      3 (10%)      3 (12%)      1 (4%)       2 (7%)                                
   Skin                                               (49)         (50)         (49)         (49)                                   
      Fibrosis                                                                   1 (2%)                                             
      Hyperkeratosis                                                3 (6%)       1 (2%)       1 (2%)                                
      Inflammation, Acute                              1 (2%)       2 (4%)       1 (2%)                                             
      Inflammation, Chronic Active                     3 (6%)       8 (16%)      3 (6%)       2 (4%)                                
      Inflammation, Granulomatous                                   1 (2%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   Bone                                               (50)         (50)         (50)         (50)                                   
      Fibrous Osteodystrophy                           2 (4%)       1 (2%)       2 (4%)       5 (10%)                               
      Hyperostosis                                     1 (2%)       1 (2%)       2 (4%)                                             
   Skeletal Muscle                                                 (2)                                                              
      Mineralization                                                2 (100%)                                                        
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (50)         (50)         (50)         (50)                                   
      Hemorrhage                                                    1 (2%)                    1 (2%)                                
      Necrosis                                                                   1 (2%)       2 (4%)                                
____________________________________________________________________________________________________________________________________

a  Number of animals examined microscopically at site and number of animals with lesion                                             

                                                             Page   10                                                              
NTP Experiment-Test: 05158-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                        MOLYBDENUM TRIOXIDE                                    Date: 04/04/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 01:54:06  
____________________________________________________________________________________________________________________________________

         FISCHER 344 RATS MALE                     CONTROL      10 MG/M3     30 MG/M3     100                                       
                                                                                          MG/M3                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Larynx                                             (49)         (48)         (49)         (49)                                   
      Hyperplasia                                      2 (4%)       1 (2%)                                                          
      Inflammation, Chronic                            1 (2%)                                                                       
      Metaplasia, Squamous                             1 (2%)                                                                       
      Mineralization                                                1 (2%)                                                          
      Epiglottis, Hyperplasia                          8 (16%)      5 (10%)     13 (27%)      5 (10%)                               
      Epiglottis, Inflammation, Chronic                                                       1 (2%)                                
      Epiglottis, Metaplasia, Squamous                             11 (23%)     16 (33%)     39 (80%)                               
   Lung                                               (50)         (50)         (50)         (50)                                   
      Foreign Body                                     1 (2%)                                                                       
      Hemorrhage                                                    3 (6%)       3 (6%)       1 (2%)                                
      Inflammation, Granulomatous                      1 (2%)                                                                       
      Metaplasia, Osseous                              1 (2%)                    1 (2%)                                             
      Mineralization                                   1 (2%)       2 (4%)                    2 (4%)                                
      Thrombosis                                       2 (4%)       4 (8%)       1 (2%)       1 (2%)                                
      Alveolar Epithelium, Hyperplasia                 7 (14%)      9 (18%)     12 (24%)      7 (14%)                               
      Alveolar Epithelium, Inflammation, Chronic                    1 (2%)                                                          
      Alveolus, Infiltration Cellular, Histiocyte                   1 (2%)                                                          
      Alveolus, Inflammation, Chronic                  2 (4%)       3 (6%)      25 (50%)     47 (94%)                               
      Artery, Mediastinum, Inflammation                             1 (2%)                                                          
      Artery, Mediastinum, Mineralization              1 (2%)       2 (4%)                    2 (4%)                                
      Interstitium, Fibrosis                                                     1 (2%)                                             
   Nose                                               (50)         (49)         (49)         (50)                                   
      Inflammation, Suppurative                        7 (14%)      5 (10%)      5 (10%)      3 (6%)                                
      Thrombosis                                      14 (28%)     11 (22%)     15 (31%)      9 (18%)                               
      Olfactory Epithelium, Degeneration, Hyaline     46 (92%)     43 (88%)     48 (98%)     49 (98%)                               
      Olfactory Epithelium, Metaplasia, Focal          1 (2%)                                                                       
      Respiratory Epithelium, Degeneration, Hyaline    2 (4%)       7 (14%)     48 (98%)     49 (98%)                               
      Respiratory Epithelium, Metaplasia, Squamous     1 (2%)                                                                       
   Trachea                                            (50)         (50)         (50)         (50)                                   
      Mineralization                                                1 (2%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   Eye                                                (2)          (1)                       (1)                                    
      Cataract                                         1 (50%)                                                                      
      Degeneration                                     1 (50%)      1 (100%)                  1 (100%)                              
____________________________________________________________________________________________________________________________________
                                                                                                                                    

a  Number of animals examined microscopically at site and number of animals with lesion                                             

                                                             Page   11                                                              
NTP Experiment-Test: 05158-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                        MOLYBDENUM TRIOXIDE                                    Date: 04/04/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 01:54:06  
____________________________________________________________________________________________________________________________________

         FISCHER 344 RATS MALE                     CONTROL      10 MG/M3     30 MG/M3     100                                       
                                                                                          MG/M3                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (50)         (50)         (50)         (50)                                   
      Accumulation, Hyaline Droplet                                                           1 (2%)                                
      Cyst                                                                       3 (6%)       1 (2%)                                
      Fibrosis, Focal                                  1 (2%)                                                                       
      Hyperplasia, Oncocytic                                                                  3 (6%)                                
      Infarct                                          1 (2%)       1 (2%)       2 (4%)       1 (2%)                                
      Metaplasia                                                                              1 (2%)                                
      Mineralization                                                2 (4%)       1 (2%)       3 (6%)                                
      Nephropathy                                     50 (100%)    49 (98%)     49 (98%)     48 (96%)                               
      Pelvis, Inflammation, Acute                      1 (2%)                                 1 (2%)                                
      Renal Tubule, Hyperplasia                        6 (12%)      3 (6%)       7 (14%)      4 (8%)                                
      Renal Tubule, Necrosis                                        2 (4%)                                                          
      Transitional Epithelium, Hyperplasia             3 (6%)       3 (6%)       2 (4%)       4 (8%)                                
   Urinary Bladder                                    (50)         (50)         (50)         (50)                                   
      Hemorrhage                                       1 (2%)                    1 (2%)                                             
      Inflammation, Acute                                           1 (2%)                                                          
      Inflammation, Chronic Active                                               1 (2%)       2 (4%)                                
      Mineralization                                                1 (2%)                                                          
      Capillary, Hyperplasia                                                     1 (2%)                                             
      Transitional Epithelium, Hyperplasia             1 (2%)                                 1 (2%)                                
                                                                                                                                    

a  Number of animals examined microscopically at site and number of animals with lesion                                             

                                                             Page   12                                                              
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