National Toxicology Program

National Toxicology Program
https://ntp.niehs.nih.gov/go/2948

TDMS Study 05135-07 Pathology Tables

NTP Experiment-Test: 05135-07         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                              ISOPRENE                                         Date: 09/24/97
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:49:08

                                                         2 YEAR CHRONIC




       Facility:  Battelle Northwest

       Chemical CAS #:  78-79-5

       Lock Date:  03/13/96

       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: 05135-07         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                              ISOPRENE                                         Date: 09/24/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:49:08  
____________________________________________________________________________________________________________________________________

         FISCHER 344 RATS FEMALE                   CONTROL      220 PPM      700 PPM      7000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________

DISPOSITION SUMMARY                                                                                                                 

  Animals Initially In Study                          50           50           50           50                                     
  Early Deaths                                                                                                                      
    Natural Death                                      5            5            4                                                  
    Moribund Sacrifice                                16           15           18           23                                     
  Survivors                                                                                                                         
    Terminal Sacrifice                                29           30           28           27                                     

  Animals Examined Microscopically                    50           50           50           50                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Intestine Small, Ileum                             (49)         (47)         (46)         (50)                                   
      Inflammation, Chronic Active                                               1 (2%)                                             
   Liver                                              (50)         (50)         (50)         (50)                                   
      Angiectasis                                      2 (4%)       2 (4%)       3 (6%)       4 (8%)                                
      Basophilic Focus                                36 (72%)     38 (76%)     33 (66%)     33 (66%)                               
      Clear Cell Focus                                 9 (18%)     11 (22%)     10 (20%)     11 (22%)                               
      Degeneration, Cystic                                          1 (2%)                    1 (2%)                                
      Degeneration, Fatty                                           1 (2%)                                                          
      Eosinophilic Focus                               2 (4%)       3 (6%)       1 (2%)       4 (8%)                                
      Fatty Change                                     8 (16%)      6 (12%)     11 (22%)      9 (18%)                               
      Fibrosis                                                                                1 (2%)                                
      Hepatodiaphragmatic Nodule                       2 (4%)       4 (8%)       5 (10%)      6 (12%)                               
      Inflammation, Granulomatous                                                             1 (2%)                                
      Mixed Cell Focus                                 4 (8%)      10 (20%)     10 (20%)      5 (10%)                               
      Necrosis                                                                                1 (2%)                                
      Regeneration                                                  1 (2%)       2 (4%)       3 (6%)                                
      Bile Duct, Cyst                                  1 (2%)       1 (2%)                                                          
      Bile Duct, Hyperplasia                           3 (6%)       9 (18%)      9 (18%)     10 (20%)                               
      Centrilobular, Necrosis                          5 (10%)      5 (10%)      8 (16%)      3 (6%)                                
      Periportal, Infiltration Cellular, Lymphocyte                              1 (2%)                                             
   Mesentery                                          (9)          (10)         (8)          (11)                                   
      Fat, Necrosis                                    9 (100%)    10 (100%)     8 (100%)    11 (100%)                              
   Oral Mucosa                                                     (1)          (1)                                                 
      Pharyngeal, Hyperplasia, Squamous                                          1 (100%)                                           
   Pancreas                                           (50)         (50)         (50)         (50)                                   
      Atrophy                                         18 (36%)     13 (26%)     11 (22%)     20 (40%)                               
      Basophilic Focus                                 1 (2%)                    3 (6%)       3 (6%)                                
      Hyperplasia                                                   2 (4%)                                                          
      Metaplasia, Hepatocyte                                        2 (4%)                    1 (2%)                                
   Salivary Glands                                    (50)         (50)         (50)         (50)                                   
      Atrophy                                          1 (2%)       1 (2%)                                                          
   Stomach, Forestomach                               (50)         (50)         (50)         (50)                                   
      Diverticulum                                                  1 (2%)                                                          
      Hyperplasia, Squamous                                                      1 (2%)                                             

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

                                                             Page    2                                                              
NTP Experiment-Test: 05135-07         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                              ISOPRENE                                         Date: 09/24/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:49:08  
____________________________________________________________________________________________________________________________________

         FISCHER 344 RATS FEMALE                   CONTROL      220 PPM      700 PPM      7000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ALIMENTARY SYSTEM - CONT                                                                                                            
      Necrosis                                         5 (10%)      2 (4%)       7 (14%)      3 (6%)                                
   Stomach, Glandular                                 (50)         (49)         (50)         (50)                                   
      Mineralization                                                             1 (2%)                                             
      Necrosis                                         3 (6%)       3 (6%)       4 (8%)       6 (12%)                               
   Tongue                                             (1)                       (2)                                                 
      Hyperplasia                                                                1 (50%)                                            
   Tooth                                                                        (1)          (1)                                    
      Developmental Malformation                                                 1 (100%)     1 (100%)                              
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Heart                                              (50)         (50)         (50)         (50)                                   
      Cardiomyopathy                                  35 (70%)     33 (66%)     28 (56%)     37 (74%)                               
      Mineralization                                                                          1 (2%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Cortex                                     (50)         (50)         (50)         (50)                                   
      Atrophy                                                                                 1 (2%)                                
      Degeneration, Cystic                             1 (2%)                    1 (2%)       3 (6%)                                
      Ectopic Tissue                                                1 (2%)                                                          
      Hyperplasia                                     25 (50%)     17 (34%)     20 (40%)     13 (26%)                               
      Hypertrophy                                      9 (18%)     14 (28%)      8 (16%)     14 (28%)                               
      Inflammation, Granulomatous                                   1 (2%)                                                          
      Necrosis                                         2 (4%)                                 1 (2%)                                
      Thrombosis                                                                              1 (2%)                                
      Vacuolization Cytoplasmic                        4 (8%)       6 (12%)      4 (8%)       6 (12%)                               
   Adrenal Medulla                                    (50)         (50)         (50)         (50)                                   
      Hyperplasia                                     11 (22%)      6 (12%)      9 (18%)      9 (18%)                               
   Islets, Pancreatic                                 (49)         (50)         (50)         (50)                                   
      Hyperplasia                                      2 (4%)                    1 (2%)       2 (4%)                                
   Parathyroid Gland                                  (48)         (43)         (43)         (45)                                   
      Hyperplasia                                                                1 (2%)                                             
   Pituitary Gland                                    (50)         (50)         (50)         (50)                                   
      Pars Distalis, Hyperplasia                      12 (24%)     16 (32%)      7 (14%)     12 (24%)                               
   Thyroid Gland                                      (48)         (50)         (49)         (50)                                   
      C-Cell, Hyperplasia                             40 (83%)     32 (64%)     38 (78%)     40 (80%)                               
      Follicular Cell, Hyperplasia                     1 (2%)       1 (2%)       1 (2%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    

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

                                                             Page    3                                                              
NTP Experiment-Test: 05135-07         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                              ISOPRENE                                         Date: 09/24/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:49:08  
____________________________________________________________________________________________________________________________________

         FISCHER 344 RATS FEMALE                   CONTROL      220 PPM      700 PPM      7000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Clitoral Gland                                     (47)         (48)         (46)         (48)                                   
      Hyperplasia                                      2 (4%)       4 (8%)       2 (4%)       3 (6%)                                
      Inflammation, Chronic Active                                  1 (2%)                                                          
   Ovary                                              (50)         (50)         (50)         (50)                                   
      Cyst                                             5 (10%)      3 (6%)       5 (10%)      6 (12%)                               
      Inflammation, Granulomatous                                   1 (2%)                    2 (4%)                                
   Uterus                                             (50)         (50)         (50)         (50)                                   
      Inflammation, Chronic Active                     1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Bone Marrow                                        (49)         (49)         (50)         (50)                                   
      Atrophy                                                                                 1 (2%)                                
      Hyperplasia, Histiocytic                                      1 (2%)                                                          
      Hyperplasia, Reticulum Cell                                   1 (2%)                                                          
      Myelofibrosis                                    1 (2%)                    1 (2%)                                             
   Spleen                                             (50)         (50)         (50)         (50)                                   
      Fibrosis                                         4 (8%)       6 (12%)     10 (20%)      4 (8%)                                
      Hematopoietic Cell Proliferation                 4 (8%)       5 (10%)                   1 (2%)                                
      Hemorrhage                                       1 (2%)       2 (4%)       4 (8%)                                             
      Metaplasia, Osseous                                           1 (2%)                                                          
      Necrosis                                         1 (2%)                                 1 (2%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Mammary Gland                                      (50)         (50)         (50)         (50)                                   
      Galactocele                                      1 (2%)       1 (2%)       1 (2%)                                             
      Hyperplasia                                      1 (2%)                                 2 (4%)                                
   Skin                                               (50)         (50)         (50)         (50)                                   
      Cyst Epithelial Inclusion                        1 (2%)                                                                       
      Inflammation, Chronic Active                     1 (2%)       2 (4%)                    2 (4%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   Bone                                               (50)         (50)         (50)         (50)                                   
      Fibrous Osteodystrophy                           1 (2%)                                                                       
      Hyperostosis                                     6 (12%)      8 (16%)     11 (22%)      8 (16%)                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    

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

                                                             Page    4                                                              
NTP Experiment-Test: 05135-07         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                              ISOPRENE                                         Date: 09/24/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:49:08  
____________________________________________________________________________________________________________________________________

         FISCHER 344 RATS FEMALE                   CONTROL      220 PPM      700 PPM      7000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (50)         (50)         (50)         (50)                                   
      Degeneration, Focal                                           1 (2%)                    1 (2%)                                
      Gliosis                                          1 (2%)                                 1 (2%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Lung                                               (50)         (50)         (50)         (50)                                   
      Inflammation, Chronic Active                    31 (62%)     29 (58%)     25 (50%)     19 (38%)                               
      Alveolar Epithelium, Hyperplasia                 5 (10%)      5 (10%)     10 (20%)      8 (16%)                               
   Nose                                               (50)         (50)         (50)         (50)                                   
      Foreign Body                                     1 (2%)       1 (2%)       1 (2%)       4 (8%)                                
      Inflammation, Suppurative                        5 (10%)      8 (16%)      8 (16%)     12 (24%)                               
      Thrombosis                                       2 (4%)       2 (4%)       3 (6%)       1 (2%)                                
      Olfactory Epithelium, Atrophy                                 1 (2%)       2 (4%)       2 (4%)                                
      Olfactory Epithelium, Hyperplasia                                          1 (2%)                                             
      Olfactory Epithelium, Metaplasia                 1 (2%)       2 (4%)       1 (2%)       1 (2%)                                
      Respiratory Epithelium, Hyperplasia                           1 (2%)                    1 (2%)                                
      Respiratory Epithelium, Metaplasia, Squamous                  1 (2%)       1 (2%)       1 (2%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   Eye                                                (5)          (4)          (3)          (6)                                    
      Cataract                                         5 (100%)     3 (75%)      3 (100%)     4 (67%)                               
      Degeneration                                                  1 (25%)                   1 (17%)                               
      Hemorrhage                                                                              1 (17%)                               
      Retina, Atrophy                                  5 (100%)     2 (50%)      3 (100%)     4 (67%)                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (50)         (49)         (50)         (50)                                   
      Cyst                                             1 (2%)                                 1 (2%)                                
      Hydronephrosis                                                1 (2%)                                                          
      Infarct                                                       1 (2%)       1 (2%)                                             
      Nephropathy                                     46 (92%)     47 (96%)     48 (96%)     47 (94%)                               
      Papilla, Necrosis                                             1 (2%)                                                          
      Renal Tubule, Hyperplasia                        4 (8%)                                                                       
      Renal Tubule, Necrosis                                                                  1 (2%)                                
      Transitional Epithelium, Hyperplasia                                                    1 (2%)                                
   Urinary Bladder                                    (50)         (50)         (50)         (50)                                   

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

                                                             Page    5                                                              
NTP Experiment-Test: 05135-07         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                              ISOPRENE                                         Date: 09/24/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:49:08  
____________________________________________________________________________________________________________________________________

         FISCHER 344 RATS FEMALE                   CONTROL      220 PPM      700 PPM      7000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
URINARY SYSTEM - CONT                                                                                                               
      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: 05135-07         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                              ISOPRENE                                         Date: 09/24/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:49:08  
____________________________________________________________________________________________________________________________________

         FISCHER 344 RATS MALE                     CONTROL      220 PPM      700 PPM      7000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________

DISPOSITION SUMMARY                                                                                                                 

  Animals Initially In Study                          50           50           50           50                                     
  Early Deaths                                                                                                                      
    Moribund Sacrifice                                28           29           30           30                                     
    Natural Death                                      4            5            5            5                                     
  Survivors                                                                                                                         
    Moribund Sacrifice                                                           1                                                  
    Terminal Sacrifice                                18           16           14           15                                     

  Animals Examined Microscopically                    50           50           50           50                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Intestine Large, Rectum                            (47)         (49)         (46)         (50)                                   
      Inflammation, Acute                                                        2 (4%)                                             
   Intestine Large, Cecum                             (48)         (47)         (46)         (50)                                   
      Diverticulum                                                               1 (2%)                                             
      Inflammation, Acute                              1 (2%)                                                                       
      Mineralization                                                             1 (2%)                                             
   Intestine Small, Duodenum                          (49)         (49)         (48)         (49)                                   
      Inflammation, Acute                              1 (2%)                    1 (2%)       1 (2%)                                
      Necrosis                                         1 (2%)       1 (2%)       2 (4%)       2 (4%)                                
   Intestine Small, Ileum                             (46)         (47)         (47)         (49)                                   
      Inflammation, Chronic Active                                               1 (2%)                                             
      Necrosis                                                                   1 (2%)                                             
   Liver                                              (50)         (50)         (50)         (50)                                   
      Angiectasis                                      2 (4%)                    5 (10%)      3 (6%)                                
      Basophilic Focus                                17 (34%)     13 (26%)     13 (26%)     16 (32%)                               
      Clear Cell Focus                                 6 (12%)      9 (18%)      7 (14%)      8 (16%)                               
      Degeneration, Cystic                             9 (18%)      9 (18%)     14 (28%)     17 (34%)                               
      Eosinophilic Focus                               2 (4%)       4 (8%)       3 (6%)       3 (6%)                                
      Fatty Change                                    15 (30%)     12 (24%)      9 (18%)     11 (22%)                               
      Hematopoietic Cell Proliferation                 1 (2%)                                 1 (2%)                                
      Hepatodiaphragmatic Nodule                       1 (2%)       1 (2%)       4 (8%)       4 (8%)                                
      Infarct                                                                                 1 (2%)                                
      Inflammation, Acute                                                        1 (2%)                                             
      Inflammation, Chronic Active                                  1 (2%)                                                          
      Inflammation, Granulomatous                                   1 (2%)                                                          
      Mineralization                                   1 (2%)                                                                       
      Mixed Cell Focus                                                                        1 (2%)                                
      Necrosis                                                      1 (2%)       1 (2%)       1 (2%)                                
      Regeneration                                     2 (4%)                    2 (4%)       6 (12%)                               
      Artery, Inflammation, Chronic Active                                                    1 (2%)                                
      Bile Duct, Hyperplasia                          25 (50%)     32 (64%)     36 (72%)     29 (58%)                               
      Centrilobular, Necrosis                          7 (14%)     11 (22%)     10 (20%)      9 (18%)                               
   Mesentery                                          (8)          (12)         (11)         (11)                                   

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

                                                             Page    7                                                              
NTP Experiment-Test: 05135-07         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                              ISOPRENE                                         Date: 09/24/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:49:08  
____________________________________________________________________________________________________________________________________

         FISCHER 344 RATS MALE                     CONTROL      220 PPM      700 PPM      7000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ALIMENTARY SYSTEM - CONT                                                                                                            
      Thrombosis                                                                 1 (9%)                                             
      Artery, Mineralization                                                     1 (9%)       2 (18%)                               
      Fat, Hemorrhage                                  1 (13%)      1 (8%)       1 (9%)       1 (9%)                                
      Fat, Inflammation, Chronic Active                                          1 (9%)       1 (9%)                                
      Fat, Necrosis                                    6 (75%)     10 (83%)      8 (73%)      6 (55%)                               
   Oral Mucosa                                        (1)          (1)                                                              
      Pharyngeal, Hyperplasia, Squamous                             1 (100%)                                                        
   Pancreas                                           (50)         (50)         (50)         (50)                                   
      Atrophy                                         18 (36%)     23 (46%)     23 (46%)     15 (30%)                               
      Basophilic Focus                                 1 (2%)       4 (8%)       1 (2%)       3 (6%)                                
      Hyperplasia                                      4 (8%)       6 (12%)      9 (18%)      7 (14%)                               
   Salivary Glands                                    (50)         (50)         (50)         (50)                                   
      Atrophy                                          1 (2%)                                                                       
   Stomach, Forestomach                               (50)         (50)         (50)         (50)                                   
      Fibrosis                                                                                1 (2%)                                
      Hyperplasia, Squamous                                         1 (2%)       1 (2%)       1 (2%)                                
      Inflammation, Acute                              1 (2%)                    1 (2%)                                             
      Mineralization                                                             2 (4%)                                             
      Necrosis                                        14 (28%)      8 (16%)     10 (20%)     12 (24%)                               
   Stomach, Glandular                                 (50)         (50)         (50)         (50)                                   
      Mineralization                                   5 (10%)      1 (2%)       4 (8%)       4 (8%)                                
      Necrosis                                         6 (12%)      3 (6%)       7 (14%)      9 (18%)                               
   Tongue                                                                       (1)          (1)                                    
      Hyperplasia                                                                1 (100%)                                           
   Tooth                                                           (1)                                                              
      Developmental Malformation                                    1 (100%)                                                        
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Blood Vessel                                       (1)                       (2)          (3)                                    
      Inflammation                                     1 (100%)                                                                     
      Aorta, Mineralization                                                      2 (100%)     3 (100%)                              
      Endothelium, Hyperplasia                         1 (100%)                                                                     
   Heart                                              (50)         (50)         (50)         (50)                                   
      Cardiomyopathy                                  41 (82%)     44 (88%)     44 (88%)     38 (76%)                               
      Artery, Mineralization                           1 (2%)                    2 (4%)       4 (8%)                                
      Atrium, Thrombosis                               4 (8%)       3 (6%)       3 (6%)       5 (10%)                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Cortex                                     (50)         (50)         (50)         (50)                                   
      Atrophy                                          1 (2%)                                 1 (2%)                                
      Degeneration, Cystic                                                                    1 (2%)                                
      Hyperplasia                                     23 (46%)     23 (46%)     19 (38%)     20 (40%)                               
      Hypertrophy                                      8 (16%)     11 (22%)      4 (8%)       4 (8%)                                

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

                                                             Page    8                                                              
NTP Experiment-Test: 05135-07         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                              ISOPRENE                                         Date: 09/24/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:49:08  
____________________________________________________________________________________________________________________________________

         FISCHER 344 RATS MALE                     CONTROL      220 PPM      700 PPM      7000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ENDOCRINE SYSTEM - CONT                                                                                                             
      Necrosis                                                                   1 (2%)                                             
      Thrombosis                                                                              1 (2%)                                
      Vacuolization Cytoplasmic                        2 (4%)       6 (12%)      3 (6%)       6 (12%)                               
   Adrenal Medulla                                    (50)         (50)         (50)         (50)                                   
      Angiectasis                                                   1 (2%)                                                          
      Hyperplasia                                     19 (38%)     19 (38%)     25 (50%)     21 (42%)                               
      Thrombosis                                                                              1 (2%)                                
      Bilateral, Hyperplasia                                                     2 (4%)                                             
   Islets, Pancreatic                                 (50)         (50)         (50)         (49)                                   
      Hyperplasia                                                   1 (2%)       3 (6%)                                             
   Parathyroid Gland                                  (48)         (46)         (45)         (47)                                   
      Cyst                                                          1 (2%)                                                          
      Hyperplasia                                      5 (10%)      6 (13%)      8 (18%)     13 (28%)                               
   Pituitary Gland                                    (50)         (50)         (50)         (49)                                   
      Pars Distalis, Hyperplasia                       5 (10%)      6 (12%)      9 (18%)     11 (22%)                               
      Pars Intermedia, Hyperplasia                                                            1 (2%)                                
   Thyroid Gland                                      (49)         (50)         (49)         (50)                                   
      C-Cell, Hyperplasia                             30 (61%)     30 (60%)     30 (61%)     34 (68%)                               
      Follicular Cell, Hyperplasia                     1 (2%)       1 (2%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Epididymis                                         (50)         (50)         (50)         (50)                                   
      Granuloma Sperm                                  1 (2%)                    1 (2%)                                             
   Preputial Gland                                    (50)         (50)         (50)         (50)                                   
      Hyperplasia                                                   1 (2%)                    1 (2%)                                
      Inflammation, Chronic Active                     3 (6%)       1 (2%)       1 (2%)       3 (6%)                                
   Prostate                                           (50)         (50)         (50)         (50)                                   
      Hyperplasia                                     11 (22%)     13 (26%)     15 (30%)     17 (34%)                               
      Inflammation, Chronic Active                     5 (10%)      2 (4%)       1 (2%)       6 (12%)                               
   Seminal Vesicle                                    (47)         (48)         (47)         (50)                                   
      Inflammation, Chronic Active                     1 (2%)                                                                       
   Testes                                             (50)         (50)         (50)         (50)                                   
      Atrophy                                          1 (2%)       1 (2%)       1 (2%)                                             
      Artery, Inflammation, Chronic Active             6 (12%)      2 (4%)       1 (2%)                                             
      Interstitial Cell, Hyperplasia                  15 (30%)     13 (26%)      8 (16%)                                            
____________________________________________________________________________________________________________________________________
                                                                                                                                    

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

                                                             Page    9                                                              
NTP Experiment-Test: 05135-07         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                              ISOPRENE                                         Date: 09/24/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:49:08  
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         FISCHER 344 RATS MALE                     CONTROL      220 PPM      700 PPM      7000 PPM                                  
                                                                                                                                    
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 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Bone Marrow                                        (50)         (50)         (49)         (50)                                   
      Hyperplasia, Histiocytic                                      1 (2%)                                                          
      Myelofibrosis                                                                           1 (2%)                                
      Necrosis                                                                                2 (4%)                                
   Lymph Node                                         (6)          (7)          (7)          (9)                                    
      Iliac, Ectasia                                   1 (17%)                                                                      
      Renal, Hemorrhage                                                                       1 (11%)                               
   Lymph Node, Mandibular                             (49)         (46)         (46)         (44)                                   
      Infiltration Cellular, Plasma Cell                            2 (4%)                                                          
   Lymph Node, Mesenteric                             (50)         (49)         (49)         (50)                                   
      Infiltration Cellular, Plasma Cell                                                      1 (2%)                                
   Spleen                                             (50)         (50)         (50)         (50)                                   
      Depletion Cellular                                                                      1 (2%)                                
      Fibrosis                                        11 (22%)     14 (28%)     24 (48%)     22 (44%)                               
      Hematopoietic Cell Proliferation                 3 (6%)       3 (6%)       1 (2%)       5 (10%)                               
      Hemorrhage                                       1 (2%)                                                                       
      Necrosis                                         3 (6%)                    2 (4%)       1 (2%)                                
   Thymus                                             (47)         (44)         (49)         (47)                                   
      Atrophy                                                                                 1 (2%)                                
      Cyst                                             1 (2%)                                                                       
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 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Mammary Gland                                      (42)         (43)         (47)         (44)                                   
      Galactocele                                      2 (5%)       4 (9%)       2 (4%)       3 (7%)                                
      Inflammation, Chronic                            1 (2%)                                                                       
   Skin                                               (50)         (50)         (50)         (50)                                   
      Cyst Epithelial Inclusion                        2 (4%)                                 2 (4%)                                
      Inflammation, Chronic Active                                  1 (2%)       2 (4%)                                             
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 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   Bone                                               (50)         (50)         (50)         (50)                                   
      Fibrous Osteodystrophy                           2 (4%)       1 (2%)       6 (12%)      7 (14%)                               
      Hyperostosis                                                  1 (2%)       1 (2%)       2 (4%)                                
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 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (50)         (50)         (50)         (50)                                   
      Degeneration, Focal                              1 (2%)                                                                       
      Gliosis                                                       1 (2%)                                                          
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a  Number of animals examined microscopically at site and number of animals with lesion                                             

                                                             Page   10                                                              
NTP Experiment-Test: 05135-07         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                              ISOPRENE                                         Date: 09/24/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:49:08  
____________________________________________________________________________________________________________________________________

         FISCHER 344 RATS MALE                     CONTROL      220 PPM      700 PPM      7000 PPM                                  
                                                                                                                                    
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 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Lung                                               (49)         (50)         (50)         (50)                                   
      Inflammation, Chronic, Focal                                  1 (2%)                                                          
      Inflammation, Chronic Active                    21 (43%)     16 (32%)     22 (44%)     15 (30%)                               
      Mineralization                                                             2 (4%)       2 (4%)                                
      Thrombosis                                                    1 (2%)                    1 (2%)                                
      Alveolar Epithelium, Hyperplasia                 7 (14%)     11 (22%)      4 (8%)      10 (20%)                               
      Artery, Mediastinum, Mineralization                                        2 (4%)       2 (4%)                                
   Nose                                               (50)         (50)         (49)         (50)                                   
      Foreign Body                                     4 (8%)       4 (8%)       3 (6%)       2 (4%)                                
      Inflammation, Suppurative                       11 (22%)      9 (18%)     10 (20%)      9 (18%)                               
      Thrombosis                                       2 (4%)       4 (8%)      10 (20%)      5 (10%)                               
      Olfactory Epithelium, Atrophy                    1 (2%)                    8 (16%)      2 (4%)                                
      Olfactory Epithelium, Metaplasia                 7 (14%)      2 (4%)       1 (2%)       2 (4%)                                
      Olfactory Epithelium, Metaplasia, Squamous       1 (2%)                                                                       
      Respiratory Epithelium, Hyperplasia                           2 (4%)       2 (4%)       2 (4%)                                
      Respiratory Epithelium, Metaplasia, Squamous                               1 (2%)                                             
   Trachea                                            (50)         (50)         (50)         (50)                                   
      Mineralization                                                             1 (2%)                                             
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 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   Eye                                                (1)          (3)          (3)          (2)                                    
      Cataract                                         1 (100%)     1 (33%)      3 (100%)     2 (100%)                              
      Hemorrhage                                                                 1 (33%)                                            
      Cornea, Inflammation, Chronic Active                          1 (33%)      1 (33%)                                            
      Retina, Atrophy                                  1 (100%)     2 (67%)      3 (100%)     2 (100%)                              
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 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (50)         (50)         (50)         (50)                                   
      Cyst                                             2 (4%)                    4 (8%)       2 (4%)                                
      Infarct                                          1 (2%)       1 (2%)       2 (4%)                                             
      Mineralization                                                             2 (4%)       3 (6%)                                
      Nephropathy                                     50 (100%)    50 (100%)    50 (100%)    49 (98%)                               
      Renal Tubule, Hyperplasia                                     2 (4%)       6 (12%)      8 (16%)                               
   Urinary Bladder                                    (50)         (49)         (50)         (50)                                   
      Hemorrhage                                                                              1 (2%)                                
      Inflammation, Acute                                                                     1 (2%)                                
      Inflammation, Chronic Active                     1 (2%)                                 1 (2%)                                
      Necrosis                                                                                1 (2%)                                

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

                                                             Page   11                                                              
NTP Experiment-Test: 05135-07         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                              ISOPRENE                                         Date: 09/24/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:49:08  
____________________________________________________________________________________________________________________________________

         FISCHER 344 RATS MALE                     CONTROL      220 PPM      700 PPM      7000 PPM                                  
                                                                                                                                    
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URINARY SYSTEM - CONT                                                                                                               
      Transitional Epithelium, Hyperplasia             1 (2%)                                                                       
                                                                                                                                    

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

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