National Toxicology Program

National Toxicology Program
https://ntp.niehs.nih.gov/go/2952

TDMS Study 05135-07 Pathology Tables

NTP Experiment-Test: 05135-07  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                              ISOPRENE                                         Date: 09/24/97
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:55:11

                                                         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 NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                              ISOPRENE                                         Date: 09/24/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:55:11  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         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                                                                                                                  
                                                                                                                                    
   Esophagus                                          (50)         (50)         (50)         (50)                                   
   Intestine Large, Colon                             (50)         (48)         (49)         (50)                                   
   Intestine Large, Cecum                             (49)         (47)         (47)         (50)                                   
   Intestine Small, Duodenum                          (49)         (48)         (50)         (50)                                   
      Fibroma                                                       1 (2%)                                                          
   Liver                                              (50)         (50)         (50)         (50)                                   
      Hepatocellular Carcinoma                                                                1 (2%)                                
      Hepatocellular Adenoma                                                     1 (2%)                                             
      Histiocytic Sarcoma                                                                     1 (2%)                                
   Mesentery                                          (9)          (10)         (8)          (11)                                   
   Oral Mucosa                                                     (1)          (1)                                                 
      Pharyngeal, Squamous Cell Carcinoma                           1 (100%)                                                        
   Pancreas                                           (50)         (50)         (50)         (50)                                   
   Salivary Glands                                    (50)         (50)         (50)         (50)                                   
   Stomach, Forestomach                               (50)         (50)         (50)         (50)                                   
      Squamous Cell Papilloma                                                                 1 (2%)                                
   Stomach, Glandular                                 (50)         (49)         (50)         (50)                                   
   Tongue                                             (1)                       (2)                                                 
      Squamous Cell Papilloma                          1 (100%)                  1 (50%)                                            
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Heart                                              (50)         (50)         (50)         (50)                                   
      Schwannoma Benign                                                          1 (2%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Cortex                                     (50)         (50)         (50)         (50)                                   
      Adenoma                                          2 (4%)       1 (2%)       2 (4%)       1 (2%)                                
   Adrenal Medulla                                    (50)         (50)         (50)         (50)                                   
      Pheochromocytoma Malignant                       1 (2%)                                                                       

                                                             Page   2                                                               
NTP Experiment-Test: 05135-07  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                              ISOPRENE                                         Date: 09/24/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:55:11  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         FISCHER 344 RATS FEMALE                   CONTROL      220 PPM      700 PPM      7000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ENDOCRINE SYSTEM - cont                                                                                                             
      Pheochromocytoma Benign                          1 (2%)       5 (10%)      4 (8%)       3 (6%)                                
   Islets, Pancreatic                                 (49)         (50)         (50)         (50)                                   
      Adenoma                                          1 (2%)       2 (4%)                                                          
      Carcinoma                                                                  2 (4%)       1 (2%)                                
   Parathyroid Gland                                  (48)         (43)         (43)         (45)                                   
   Pituitary Gland                                    (50)         (50)         (50)         (50)                                   
      Sarcoma, Metastatic, Brain                                    1 (2%)                                                          
      Pars Distalis, Adenoma                          33 (66%)     27 (54%)     36 (72%)     27 (54%)                               
      Pars Distalis, Carcinoma                         1 (2%)                    1 (2%)                                             
   Thyroid Gland                                      (48)         (50)         (49)         (50)                                   
      C-Cell, Adenoma                                  6 (13%)      4 (8%)       2 (4%)       2 (4%)                                
      C-Cell, Carcinoma                                2 (4%)       4 (8%)       2 (4%)                                             
      Follicular Cell, Adenoma                                                   1 (2%)                                             
      Follicular Cell, Carcinoma                                                              1 (2%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Clitoral Gland                                     (47)         (48)         (46)         (48)                                   
      Adenoma                                          3 (6%)       5 (10%)      5 (11%)      6 (13%)                               
      Carcinoma                                        2 (4%)       4 (8%)       2 (4%)       2 (4%)                                
      Bilateral, Carcinoma                                          1 (2%)                                                          
   Ovary                                              (50)         (50)         (50)         (50)                                   
      Granulosa Cell Tumor Malignant                   1 (2%)                                 1 (2%)                                
      Granulosa Cell Tumor Benign                      1 (2%)                                                                       
   Uterus                                             (50)         (50)         (50)         (50)                                   
      Polyp Stromal                                    8 (16%)      4 (8%)       5 (10%)      7 (14%)                               
      Polyp Stromal, Multiple                                       1 (2%)       1 (2%)       1 (2%)                                
      Sarcoma Stromal                                  1 (2%)       1 (2%)                                                          
      Endometrium, Adenoma                             1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Bone Marrow                                        (49)         (49)         (50)         (50)                                   
      Histiocytic Sarcoma                                                                     1 (2%)                                
   Lymph Node                                                      (6)          (4)          (2)                                    
   Lymph Node, Bronchial                              (42)         (37)         (34)         (35)                                   
   Lymph Node, Mandibular                             (45)         (47)         (49)         (46)                                   
   Lymph Node, Mesenteric                             (50)         (50)         (50)         (50)                                   
   Lymph Node, Mediastinal                            (44)         (44)         (42)         (44)                                   
   Spleen                                             (50)         (50)         (50)         (50)                                   

                                                             Page   3                                                               
NTP Experiment-Test: 05135-07  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                              ISOPRENE                                         Date: 09/24/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:55:11  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         FISCHER 344 RATS FEMALE                   CONTROL      220 PPM      700 PPM      7000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
HEMATOPOIETIC SYSTEM - cont                                                                                                         
      Sarcoma                                          1 (2%)                                                                       
   Thymus                                             (48)         (45)         (39)         (46)                                   
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Mammary Gland                                      (50)         (50)         (50)         (50)                                   
      Carcinoma                                        4 (8%)       2 (4%)       1 (2%)       3 (6%)                                
      Fibroadenoma                                    12 (24%)     23 (46%)     13 (26%)     15 (30%)                               
      Fibroadenoma, Multiple                           7 (14%)     12 (24%)     19 (38%)     17 (34%)                               
   Skin                                               (50)         (50)         (50)         (50)                                   
      Keratoacanthoma                                               1 (2%)                                                          
      Squamous Cell Papilloma                          2 (4%)       1 (2%)                                                          
      Sebaceous Gland, Adenoma                                      1 (2%)                                                          
      Subcutaneous Tissue, Fibroma                                               1 (2%)                                             
      Subcutaneous Tissue, Fibrosarcoma                1 (2%)                                                                       
      Subcutaneous Tissue, Lipoma                                                             1 (2%)                                
      Subcutaneous Tissue, Sarcoma                     1 (2%)       1 (2%)                    1 (2%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   Skeletal Muscle                                    (1)                                                                           
      Rhabdomyosarcoma                                 1 (100%)                                                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (50)         (50)         (50)         (50)                                   
      Astrocytoma Benign                                                         1 (2%)                                             
      Carcinoma, Metastatic, Pituitary Gland           2 (4%)                    1 (2%)                                             
      Glioma Malignant                                                                        1 (2%)                                
      Medulloblastoma Mal                                                                     1 (2%)                                
      Meninges, Granular Cell Tumor Benign                          1 (2%)                    1 (2%)                                
      Meninges, Sarcoma                                             1 (2%)                    1 (2%)                                
   Spinal Cord                                                                               (1)                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Lung                                               (50)         (50)         (50)         (50)                                   
      Alveolar/Bronchiolar Adenoma                     1 (2%)                                 2 (4%)                                
      Carcinoma, Metastatic, Thyroid Gland                          1 (2%)                                                          
   Nose                                               (50)         (50)         (50)         (50)                                   
      Squamous Cell Carcinoma, Metastatic, Oral                                                                                     
          Mucosa                                                    1 (2%)                                                          
   Pleura                                                                                    (1)                                    

                                                             Page   4                                                               
NTP Experiment-Test: 05135-07  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                              ISOPRENE                                         Date: 09/24/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:55:11  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         FISCHER 344 RATS FEMALE                   CONTROL      220 PPM      700 PPM      7000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
RESPIRATORY SYSTEM - cont                                                                                                           
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   Zymbal's Gland                                                               (1)                                                 
      Carcinoma                                                                  1 (100%)                                           
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (50)         (49)         (50)         (50)                                   
      Mesenchymal Tumor Benign                                      1 (2%)                                                          
      Sarcoma, Metastatic, Urinary Bladder                          1 (2%)                                                          
      Renal Tubule, Adenoma                                                      1 (2%)                                             
   Urinary Bladder                                    (50)         (50)         (50)         (50)                                   
      Sarcoma                                                       1 (2%)                                                          
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SYSTEMIC LESIONS                                                                                                                   

   Multiple Organs                                   *(50)        *(50)        *(50)        *(50)                                   
      Histiocytic Sarcoma                                                                     1 (2%)                                
      Leukemia Mononuclear                            14 (28%)     15 (30%)     21 (42%)     21 (42%)                               
      Mesothelioma Malignant                                                                  1 (2%)                                
____________________________________________________________________________________________________________________________________

                                                                                                                                    
     *   Number of animals with any tissue examined microscopically                                                                 

                                                             Page   5                                                               
NTP Experiment-Test: 05135-07  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                              ISOPRENE                                         Date: 09/24/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:55:11  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         FISCHER 344 RATS FEMALE                   CONTROL      220 PPM      700 PPM      7000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
TUMOR SUMMARY                                                                                                                       
                                                                                                                                    
   Total Animals with Primary Neoplasms (b)            49          48          49          48                                       
     Total Primary Neoplasms                          109         121         124         120                                       
                                                                                                                                    
   Total Animals with Benign Neoplasms                 43          43          46          41                                       
     Total Benign Neoplasms                            79          90          94          84                                       
                                                                                                                                    
   Total Animals with Malignant Neoplasms              28          27          26          31                                       
     Total Malignant Neoplasms                         30          31          30          36                                       
                                                                                                                                    
   Total Animals with Metastatic Neoplasms              2           4           1                                                   
     Total Metastatic Neoplasm                          2           4           1                                                   
                                                                                                                                    
   Total Animals with Malignant Neoplasms                                                                                           
   Uncertain Primary Site                                                                                                           
                                                                                                                                    
   Total Animals with Neoplasms Uncertain-                                                                                          
   Benign or Malignant                                                                                                              
     Total Uncertain Neoplasms                                                                                                      
                                                                                                                                    

____________________________________________________________________________________________________________________________________
a  Number of animals examined microscopically at site and number of animals with lesion                                             
b  Primary tumors: all tumors except metastatic tumors                                                                              

                                                             Page   6                                                               
NTP Experiment-Test: 05135-07  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                              ISOPRENE                                         Date: 09/24/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:55:11  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         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, Colon                             (49)         (49)         (47)         (50)                                   
   Intestine Large, Rectum                            (47)         (49)         (46)         (50)                                   
      Anus, Leiomyoma                                                            1 (2%)                                             
      Anus, Squamous Cell Papilloma                                 1 (2%)                                                          
   Intestine Large, Cecum                             (48)         (47)         (46)         (50)                                   
   Intestine Small, Jejunum                           (46)         (46)         (47)         (47)                                   
      Carcinoma                                                                               1 (2%)                                
   Intestine Small, Ileum                             (46)         (47)         (47)         (49)                                   
   Liver                                              (50)         (50)         (50)         (50)                                   
      Hepatocellular Carcinoma                                      1 (2%)                                                          
      Hepatocellular Adenoma                                        2 (4%)                                                          
      Histiocytic Sarcoma                                           1 (2%)                                                          
      Osteosarcoma, Metastatic, Bone                                                          1 (2%)                                
   Mesentery                                          (8)          (12)         (11)         (11)                                   
   Oral Mucosa                                        (1)          (1)                                                              
      Gingival, Sarcoma                                1 (100%)                                                                     
   Pancreas                                           (50)         (50)         (50)         (50)                                   
      Adenoma                                          3 (6%)       1 (2%)       3 (6%)                                             
   Salivary Glands                                    (50)         (50)         (50)         (50)                                   
   Stomach, Forestomach                               (50)         (50)         (50)         (50)                                   
      Histiocytic Sarcoma                                           1 (2%)                                                          
      Leiomyosarcoma                                                             1 (2%)                                             
   Stomach, Glandular                                 (50)         (50)         (50)         (50)                                   
      Carcinoid Tumor Benign                                        1 (2%)                                                          
   Tongue                                                                       (1)          (1)                                    
      Squamous Cell Papilloma                                                                 1 (100%)                              
____________________________________________________________________________________________________________________________________
                                                                                                                                    

                                                             Page   7                                                               
NTP Experiment-Test: 05135-07  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                              ISOPRENE                                         Date: 09/24/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:55:11  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         FISCHER 344 RATS MALE                     CONTROL      220 PPM      700 PPM      7000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Heart                                              (50)         (50)         (50)         (50)                                   
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Cortex                                     (50)         (50)         (50)         (50)                                   
      Adenoma                                          1 (2%)                                                                       
      Carcinoma                                                                               1 (2%)                                
   Adrenal Medulla                                    (50)         (50)         (50)         (50)                                   
      Pheochromocytoma Malignant                       3 (6%)       1 (2%)       1 (2%)                                             
      Pheochromocytoma Benign                         13 (26%)     11 (22%)     16 (32%)     15 (30%)                               
      Bilateral, Pheochromocytoma Benign               5 (10%)      4 (8%)       4 (8%)       3 (6%)                                
   Islets, Pancreatic                                 (50)         (50)         (50)         (49)                                   
      Adenoma                                          1 (2%)       2 (4%)       5 (10%)      1 (2%)                                
      Carcinoma                                        2 (4%)                    1 (2%)       1 (2%)                                
   Parathyroid Gland                                  (48)         (46)         (45)         (47)                                   
      Adenoma                                                       1 (2%)                                                          
   Pituitary Gland                                    (50)         (50)         (50)         (49)                                   
      Pars Distalis, Adenoma                          39 (78%)     40 (80%)     39 (78%)     31 (63%)                               
   Thyroid Gland                                      (49)         (50)         (49)         (50)                                   
      C-Cell, Adenoma                                  3 (6%)       4 (8%)       3 (6%)       3 (6%)                                
      C-Cell, Carcinoma                                1 (2%)       1 (2%)       1 (2%)       3 (6%)                                
      Follicular Cell, Adenoma                         1 (2%)       1 (2%)       1 (2%)                                             
      Follicular Cell, Carcinoma                       1 (2%)       1 (2%)       1 (2%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   Peritoneum                                         (2)                       (1)          (3)                                    
   Tissue NOS                                         (1)          (2)                                                              
      Osteosarcoma                                                  1 (50%)                                                         
      Sarcoma                                                       1 (50%)                                                         
      Schwannoma Malignant                             1 (100%)                                                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Epididymis                                         (50)         (50)         (50)         (50)                                   
   Preputial Gland                                    (50)         (50)         (50)         (50)                                   
      Adenoma                                          2 (4%)       1 (2%)       3 (6%)       3 (6%)                                
      Carcinoma                                        3 (6%)       2 (4%)       2 (4%)                                             
   Prostate                                           (50)         (50)         (50)         (50)                                   
      Adenoma                                                                    1 (2%)                                             
      Carcinoma                                        1 (2%)                                                                       
   Seminal Vesicle                                    (47)         (48)         (47)         (50)                                   
   Testes                                             (50)         (50)         (50)         (50)                                   

                                                             Page   8                                                               
NTP Experiment-Test: 05135-07  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                              ISOPRENE                                         Date: 09/24/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:55:11  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         FISCHER 344 RATS MALE                     CONTROL      220 PPM      700 PPM      7000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
GENITAL SYSTEM - cont                                                                                                               
      Bilateral, Interstitial Cell, Adenoma           20 (40%)     29 (58%)     37 (74%)     48 (96%)                               
      Interstitial Cell, Adenoma                      13 (26%)      8 (16%)      7 (14%)                                            
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Bone Marrow                                        (50)         (50)         (49)         (50)                                   
   Lymph Node                                         (6)          (7)          (7)          (9)                                    
   Lymph Node, Bronchial                              (44)         (39)         (42)         (35)                                   
      Histiocytic Sarcoma                                           1 (3%)                                                          
      Pheochromocytoma Malignant, Metastatic,                                                                                       
          Adrenal Medulla                                           1 (3%)                                                          
   Lymph Node, Mandibular                             (49)         (46)         (46)         (44)                                   
   Lymph Node, Mesenteric                             (50)         (49)         (49)         (50)                                   
      Histiocytic Sarcoma                                           1 (2%)                                                          
   Lymph Node, Mediastinal                            (46)         (44)         (45)         (44)                                   
      Histiocytic Sarcoma                                           1 (2%)                                                          
   Spleen                                             (50)         (50)         (50)         (50)                                   
      Histiocytic Sarcoma                                           1 (2%)                                                          
      Sarcoma                                                       1 (2%)                                                          
   Thymus                                             (47)         (44)         (49)         (47)                                   
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Mammary Gland                                      (42)         (43)         (47)         (44)                                   
      Carcinoma                                                     1 (2%)       1 (2%)       2 (5%)                                
      Fibroadenoma                                     1 (2%)       3 (7%)       6 (13%)     14 (32%)                               
      Fibroadenoma, Multiple                           1 (2%)       1 (2%)                    7 (16%)                               
   Skin                                               (50)         (50)         (50)         (50)                                   
      Basal Cell Adenoma                               1 (2%)       1 (2%)       1 (2%)       1 (2%)                                
      Keratoacanthoma                                  1 (2%)       2 (4%)       1 (2%)       2 (4%)                                
      Lipoma                                           1 (2%)                                 1 (2%)                                
      Squamous Cell Carcinoma                          1 (2%)                    1 (2%)       1 (2%)                                
      Squamous Cell Papilloma                                       1 (2%)                                                          
      Trichoepithelioma                                                          1 (2%)                                             
      Pinna, Melanoma Malignant                                                               1 (2%)                                
      Sebaceous Gland, Adenoma                                      1 (2%)                                                          
      Subcutaneous Tissue, Fibroma                                  4 (8%)       1 (2%)       2 (4%)                                
      Subcutaneous Tissue, Fibrosarcoma                                          1 (2%)                                             
      Subcutaneous Tissue, Lipoma                                   1 (2%)                                                          
      Subcutaneous Tissue, Schwannoma Malignant                                  1 (2%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    

                                                             Page   9                                                               
NTP Experiment-Test: 05135-07  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                              ISOPRENE                                         Date: 09/24/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:55:11  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         FISCHER 344 RATS MALE                     CONTROL      220 PPM      700 PPM      7000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   Bone                                               (50)         (50)         (50)         (50)                                   
      Osteoma                                                       1 (2%)                                                          
      Osteosarcoma                                                                            1 (2%)                                
      Vertebra, Chordoma                                            1 (2%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (50)         (50)         (50)         (50)                                   
      Astrocytoma Malignant                                                                   1 (2%)                                
      Granular Cell Tumor Benign                                                 1 (2%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Lung                                               (49)         (50)         (50)         (50)                                   
      Alveolar/Bronchiolar Carcinoma                   1 (2%)                                 3 (6%)                                
      Carcinoma, Metastatic, Thyroid Gland                                                    1 (2%)                                
      Chordoma, Metastatic, Bone                                    1 (2%)                                                          
      Histiocytic Sarcoma                                           1 (2%)                                                          
      Melanoma Malignant, Metastatic, Skin                                                    1 (2%)                                
      Osteosarcoma, Metastatic, Bone                                                          1 (2%)                                
      Osteosarcoma, Metastatic, Uncertain Primary                                                                                   
          Site                                                                                1 (2%)                                
      Pheochromocytoma Malignant, Metastatic,                                                                                       
          Adrenal Medulla                                           1 (2%)                                                          
      Squamous Cell Carcinoma                                       1 (2%)                                                          
      Mediastinum, Alveolar/Bronchiolar Carcinoma,                                                                                  
           Metastatic, Lung                                                                   1 (2%)                                
   Nose                                               (50)         (50)         (49)         (50)                                   
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   Zymbal's Gland                                                  (1)          (1)          (1)                                    
      Carcinoma                                                     1 (100%)     1 (100%)     1 (100%)                              
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (50)         (50)         (50)         (50)                                   
      Lipoma                                                                     1 (2%)                                             
      Mesenchymal Tumor Benign                                                                1 (2%)                                
      Renal Tubule, Adenoma                                         2 (4%)       2 (4%)       6 (12%)                               
      Renal Tubule, Carcinoma                                                    1 (2%)                                             
   Urinary Bladder                                    (50)         (49)         (50)         (50)                                   

                                                             Page  10                                                               
NTP Experiment-Test: 05135-07  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                              ISOPRENE                                         Date: 09/24/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:55:11  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         FISCHER 344 RATS MALE                     CONTROL      220 PPM      700 PPM      7000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
                                                                                                                                    
 SYSTEMIC LESIONS                                                                                                                   

   Multiple Organs                                   *(50)        *(50)        *(50)        *(50)                                   
      Histiocytic Sarcoma                                           1 (2%)                                                          
      Leukemia Mononuclear                            24 (48%)     26 (52%)     25 (50%)     25 (50%)                               
      Mesothelioma Benign                              2 (4%)       2 (4%)       1 (2%)                                             
      Mesothelioma Malignant                           3 (6%)       1 (2%)       1 (2%)       4 (8%)                                
____________________________________________________________________________________________________________________________________

                                                                                                                                    
     *   Number of animals with any tissue examined microscopically                                                                 

                                                             Page  11                                                               
NTP Experiment-Test: 05135-07  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                              ISOPRENE                                         Date: 09/24/97  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 09:55:11  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         FISCHER 344 RATS MALE                     CONTROL      220 PPM      700 PPM      7000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
TUMOR SUMMARY                                                                                                                       
                                                                                                                                    
   Total Animals with Primary Neoplasms (b)            50          50          49          48                                       
     Total Primary Neoplasms                          150         166         174         184                                       
                                                                                                                                    
   Total Animals with Benign Neoplasms                 49          50          49          48                                       
     Total Benign Neoplasms                           108         125         135         139                                       
                                                                                                                                    
   Total Animals with Malignant Neoplasms              34          33          30          34                                       
     Total Malignant Neoplasms                         42          41          39          45                                       
                                                                                                                                    
   Total Animals with Metastatic Neoplasms                          2                       5                                       
     Total Metastatic Neoplasm                                      3                       6                                       
                                                                                                                                    
   Total Animals with Malignant Neoplasms                                                   1                                       
   Uncertain Primary Site                                                                                                           
                                                                                                                                    
   Total Animals with Neoplasms Uncertain-                                                                                          
   Benign or Malignant                                                                                                              
     Total Uncertain Neoplasms                                                                                                      
                                                                                                                                    

____________________________________________________________________________________________________________________________________
a  Number of animals examined microscopically at site and number of animals with lesion                                             
b  Primary tumors: all tumors except metastatic tumors                                                                              

                                                             Page  12                                                               
                             ------------------------------------------------------------                                           
                             ----------              END OF REPORT             ----------                                           
                             ------------------------------------------------------------                                           
NTP is located at the National Institute of Environmental Health Sciences, part of the National Institutes of Health.