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https://ntp.niehs.nih.gov/go/3639

TDMS Study 05210-03 Pathology Tables

NTP Experiment-Test: 05210-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 03/14/96
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:45:33

                                                           CORE STUDY




       Facility:  I. I. T. Research Institute

       Chemical CAS #:  100-41-4

       Lock Date:  10/02/92

       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: 05210-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 03/14/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:45:33  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS FEMALE                   CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
DISPOSITION SUMMARY                                                                                                                 
  Animals Initially In Study                          50           50           50           50                                     
  Early Deaths                                                                                                                      
    Moribund Sacrifice                                 7           14            8            6                                     
    Natural Death                                     12            5            8            8                                     
  Survivors                                                                                                                         
    Terminal Sacrifice                                30           31           34           35                                     
    Natural Death                                      1                                                                            
  Missing                                                                                     1                                     
  Animals Examined Microscopically                    50           50           50           49                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Intestine Large, Colon                             (47)         (49)         (48)         (49)                                   
      Inflammation                                     1 (2%)                                                                       
   Intestine Large, Rectum                            (49)         (50)         (47)         (49)                                   
      Arteriole, Inflammation                          1 (2%)                                                                       
   Intestine Large, Cecum                             (44)         (50)         (47)         (49)                                   
      Inflammation                                     1 (2%)                                                                       
   Intestine Small, Ileum                             (41)         (48)         (47)         (46)                                   
      Hyperplasia                                                                1 (2%)                                             
      Inflammation                                                               1 (2%)                                             
   Liver                                              (50)         (50)         (50)         (49)                                   
      Angiectasis                                      3 (6%)                                 6 (12%)                               
      Basophilic Focus                                23 (46%)     29 (58%)     33 (66%)     29 (59%)                               
      Clear Cell Focus                                 3 (6%)       3 (6%)       1 (2%)       4 (8%)                                
      Congestion                                       1 (2%)                    1 (2%)       1 (2%)                                
      Degeneration                                                  1 (2%)       2 (4%)                                             
      Eosinophilic Focus                               2 (4%)       3 (6%)       8 (16%)      5 (10%)                               
      Fibrosis                                                      1 (2%)                                                          
      Hematopoietic Cell Proliferation                 1 (2%)                                                                       
      Hemorrhage                                       1 (2%)                                                                       
      Hepatodiaphragmatic Nodule                       4 (8%)       4 (8%)       4 (8%)       5 (10%)                               
      Infiltration Cellular, Lymphocyte                                          1 (2%)                                             
      Inflammation, Acute                                                                     1 (2%)                                
      Inflammation, Chronic                            3 (6%)       2 (4%)       3 (6%)       2 (4%)                                
      Mixed Cell Focus                                 5 (10%)                   1 (2%)                                             
      Necrosis                                         1 (2%)       1 (2%)       2 (4%)       2 (4%)                                
      Vacuolization Cytoplasmic                       11 (22%)     12 (24%)     14 (28%)     14 (29%)                               
      Centrilobular, Degeneration                      1 (2%)                                                                       
      Portal Vein, Thrombosis                                       1 (2%)                                                          
   Mesentery                                          (7)          (4)          (6)          (7)                                    
      Artery, Degeneration                                                       1 (17%)                                            
      Artery, Inflammation                             1 (14%)                   1 (17%)                                            
      Fat, Necrosis                                    6 (86%)      4 (100%)     5 (83%)      7 (100%)                              
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    2                                                              
NTP Experiment-Test: 05210-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 03/14/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:45:33  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS FEMALE                   CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ALIMENTARY SYSTEM - CONT                                                                                                            
   Pancreas                                           (49)         (50)         (50)         (49)                                   
      Cyst                                                                       1 (2%)                                             
      Inflammation                                     2 (4%)                                                                       
      Acinus, Atrophy                                 18 (37%)     18 (36%)     18 (36%)     19 (39%)                               
      Arteriole, Inflammation                                                    1 (2%)       1 (2%)                                
      Artery, Inflammation                             1 (2%)                    1 (2%)                                             
   Stomach, Forestomach                               (49)         (50)         (50)         (49)                                   
      Hemorrhage                                                                              1 (2%)                                
      Hyperkeratosis                                   2 (4%)                    1 (2%)                                             
      Hyperplasia                                      3 (6%)       1 (2%)       3 (6%)       8 (16%)                               
      Inflammation                                     1 (2%)       1 (2%)                    6 (12%)                               
      Ulcer                                            3 (6%)       4 (8%)       1 (2%)                                             
   Stomach, Glandular                                 (49)         (49)         (49)         (49)                                   
      Cyst                                                                                    1 (2%)                                
      Hyperplasia                                      1 (2%)                                                                       
      Inflammation                                                                            2 (4%)                                
      Necrosis                                         5 (10%)                   1 (2%)       1 (2%)                                
      Pigmentation                                     1 (2%)                                                                       
      Ulcer                                                         4 (8%)                    1 (2%)                                
      Glands, Cyst                                                                            1 (2%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Blood Vessel                                       (49)         (50)         (50)         (49)                                   
      Degeneration                                                               1 (2%)                                             
      Inflammation                                                               1 (2%)                                             
      Aorta, Inflammation                              1 (2%)                                                                       
   Heart                                              (50)         (50)         (50)         (49)                                   
      Cardiomyopathy                                   6 (12%)      1 (2%)                    6 (12%)                               
      Fibrosis                                                                                1 (2%)                                
      Inflammation                                                               1 (2%)                                             
      Atrium, Inflammation                                                       1 (2%)                                             
      Atrium, Thrombosis                                                                      1 (2%)                                
      Endocardium, Hyperplasia                                      1 (2%)       1 (2%)                                             
      Myocardium, Hypertrophy                                       1 (2%)                                                          
      Valve, Degeneration                              1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Cortex                                     (50)         (50)         (50)         (49)                                   
      Angiectasis                                      3 (6%)       3 (6%)       4 (8%)       3 (6%)                                
      Cytoplasmic Alteration                           1 (2%)       3 (6%)       1 (2%)                                             
      Degeneration                                                                            1 (2%)                                
      Degeneration, Cystic                             5 (10%)      3 (6%)       2 (4%)       4 (8%)                                
      Hemorrhage                                       4 (8%)       5 (10%)      2 (4%)       1 (2%)                                
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    3                                                              
NTP Experiment-Test: 05210-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 03/14/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:45:33  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS FEMALE                   CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ENDOCRINE SYSTEM - CONT                                                                                                             
      Hyperplasia                                      3 (6%)       4 (8%)       2 (4%)       3 (6%)                                
      Hypertrophy                                                                3 (6%)                                             
      Necrosis                                         1 (2%)                    1 (2%)       1 (2%)                                
      Pigmentation                                                               1 (2%)       1 (2%)                                
      Vacuolization Cytoplasmic                       12 (24%)      5 (10%)     12 (24%)      6 (12%)                               
   Adrenal Medulla                                    (50)         (50)         (50)         (49)                                   
      Hemorrhage                                                    1 (2%)                                                          
      Hyperplasia                                      4 (8%)                    2 (4%)       2 (4%)                                
      Infiltration Cellular, Lymphocyte                                          1 (2%)                                             
      Necrosis                                                      1 (2%)                                                          
   Parathyroid Gland                                  (48)         (46)         (42)         (47)                                   
      Atrophy                                          1 (2%)                                                                       
      Hyperplasia                                      5 (10%)      2 (4%)       4 (10%)      5 (11%)                               
   Pituitary Gland                                    (49)         (49)         (50)         (49)                                   
      Cyst                                             1 (2%)                                                                       
      Infiltration Cellular, Mixed Cell                1 (2%)                                                                       
      Necrosis                                         1 (2%)                                                                       
      Pars Distalis, Angiectasis                       2 (4%)      16 (33%)      6 (12%)      2 (4%)                                
      Pars Distalis, Cyst                              5 (10%)      1 (2%)       3 (6%)       3 (6%)                                
      Pars Distalis, Degeneration                                   1 (2%)                                                          
      Pars Distalis, Hemorrhage                                     2 (4%)                                                          
      Pars Distalis, Hyperplasia                      11 (22%)      9 (18%)     14 (28%)     17 (35%)                               
      Pars Distalis, Pigmentation                                   2 (4%)                                                          
      Pars Intermedia, Angiectasis                                  2 (4%)                                                          
   Thyroid Gland                                      (48)         (50)         (50)         (49)                                   
      Hyperplasia                                                                1 (2%)                                             
      Inflammation                                     1 (2%)                                                                       
      Bilateral, C-Cell, Hyperplasia                                                          1 (2%)                                
      C-Cell, Hyperplasia                              5 (10%)      5 (10%)      5 (10%)      5 (10%)                               
      C-Cell, Inflammation                             1 (2%)                                                                       
      Follicle, Cyst                                                             1 (2%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Clitoral Gland                                     (47)         (49)         (48)         (47)                                   
      Cyst                                                                                    1 (2%)                                
      Hyperplasia                                      4 (9%)       3 (6%)       1 (2%)       3 (6%)                                
      Inflammation                                     6 (13%)      5 (10%)      4 (8%)       4 (9%)                                
      Bilateral, Hyperplasia                                                                  1 (2%)                                
   Ovary                                              (50)         (50)         (50)         (49)                                   
      Cyst                                             5 (10%)      6 (12%)      5 (10%)      5 (10%)                               
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    4                                                              
NTP Experiment-Test: 05210-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 03/14/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:45:33  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS FEMALE                   CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
GENITAL SYSTEM - CONT                                                                                                               
      Corpus Luteum, Hyperplasia                       1 (2%)                                                                       
   Uterus                                             (50)         (50)         (50)         (49)                                   
      Angiectasis                                      1 (2%)                                                                       
      Hydrometra                                       1 (2%)       3 (6%)       1 (2%)       4 (8%)                                
      Inflammation                                                               1 (2%)       1 (2%)                                
      Endometrium, Cyst                                                                       1 (2%)                                
   Vagina                                                          (3)                                                              
      Fibrosis                                                      1 (33%)                                                         
      Arteriole, Degeneration                                       1 (33%)                                                         
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Bone Marrow                                        (49)         (50)         (50)         (49)                                   
      Atrophy                                          1 (2%)                                 1 (2%)                                
      Hemorrhage                                       3 (6%)       2 (4%)                    1 (2%)                                
      Hyperplasia                                      7 (14%)      8 (16%)      7 (14%)      8 (16%)                               
      Hyperplasia, Mast Cell                                        1 (2%)                                                          
      Myelofibrosis                                    1 (2%)                                                                       
      Myelostromal Proliferation                                    1 (2%)       1 (2%)                                             
      Erythroid Cell, Hyperplasia                                                             1 (2%)                                
      Myeloid Cell, Hyperplasia                                     1 (2%)       1 (2%)                                             
   Lymph Node                                         (3)          (3)          (4)          (4)                                    
      Pancreatic, Hemorrhage                                                     1 (25%)      1 (25%)                               
      Pancreatic, Infiltration Cellular, Histiocyte                                           1 (25%)                               
      Renal, Hemorrhage                                                                       2 (50%)                               
      Renal, Pigmentation                                                                     1 (25%)                               
   Lymph Node, Bronchial                              (37)         (34)         (41)         (38)                                   
      Atrophy                                          1 (3%)                                                                       
      Ectasia                                                                    1 (2%)                                             
      Hemorrhage                                       4 (11%)      6 (18%)      5 (12%)      3 (8%)                                
      Hyperplasia, Lymphoid                                         1 (3%)                                                          
      Infiltration Cellular, Histiocyte                                          1 (2%)                                             
      Necrosis                                                                   1 (2%)                                             
      Pigmentation                                     6 (16%)      7 (21%)      7 (17%)      5 (13%)                               
   Lymph Node, Mandibular                             (49)         (50)         (50)         (49)                                   
      Ectasia                                                       1 (2%)       1 (2%)                                             
      Hemorrhage                                       3 (6%)       2 (4%)       1 (2%)       3 (6%)                                
      Hyperplasia, Plasma Cell                         2 (4%)       9 (18%)      4 (8%)       3 (6%)                                
      Infiltration Cellular, Histiocyte                1 (2%)                                                                       
      Pigmentation                                                                            1 (2%)                                
   Lymph Node, Mesenteric                             (49)         (50)         (50)         (49)                                   
      Amyloid Deposition                               1 (2%)                                                                       
      Atrophy                                          1 (2%)                                                                       
      Ectasia                                                                    3 (6%)                                             
      Hemorrhage                                       8 (16%)      6 (12%)      8 (16%)      7 (14%)                               
      Hyperplasia                                                                             1 (2%)                                
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    5                                                              
NTP Experiment-Test: 05210-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 03/14/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:45:33  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS FEMALE                   CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
HEMATOPOIETIC SYSTEM - CONT                                                                                                         
      Hyperplasia, Plasma Cell                                                   1 (2%)                                             
      Infiltration Cellular, Histiocyte                1 (2%)                                                                       
      Inflammation                                     1 (2%)                    1 (2%)                                             
   Lymph Node, Mediastinal                            (49)         (49)         (50)         (49)                                   
      Edema                                                         1 (2%)                                                          
      Hemorrhage                                      21 (43%)     15 (31%)     13 (26%)     21 (43%)                               
      Hyperplasia, Plasma Cell                         1 (2%)                                                                       
      Infiltration Cellular, Histiocyte                1 (2%)                                                                       
      Necrosis                                         1 (2%)                                                                       
      Pigmentation                                    22 (45%)     22 (45%)     25 (50%)     27 (55%)                               
   Spleen                                             (49)         (50)         (49)         (49)                                   
      Hematopoietic Cell Proliferation                 6 (12%)      3 (6%)       3 (6%)       3 (6%)                                
      Hemorrhage                                                    2 (4%)                                                          
      Hyperplasia, Lymphoid                                         1 (2%)                                                          
      Necrosis                                                                                1 (2%)                                
      Pigmentation                                     1 (2%)       1 (2%)                                                          
      Red Pulp, Atrophy                                1 (2%)                                                                       
   Thymus                                             (48)         (47)         (47)         (47)                                   
      Atrophy                                          1 (2%)                                                                       
      Cyst                                                                                    2 (4%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Mammary Gland                                      (48)         (50)         (49)         (49)                                   
      Galactocele                                     10 (21%)     10 (20%)     10 (20%)     11 (22%)                               
      Hyperplasia                                     13 (27%)     19 (38%)     21 (43%)     18 (37%)                               
      Infiltration Cellular, Lymphocyte                             1 (2%)                                                          
   Skin                                               (50)         (50)         (50)         (49)                                   
      Cyst Epithelial Inclusion                                                  1 (2%)                                             
      Infiltration Cellular, Lymphocyte                             1 (2%)                                                          
      Inflammation, Chronic                            1 (2%)                                                                       
      Ulcer                                            1 (2%)                    1 (2%)       2 (4%)                                
      Epidermis, Hyperplasia                                                     2 (4%)       1 (2%)                                
      Subcutaneous Tissue, Fibrosis                                 1 (2%)                                                          
      Subcutaneous Tissue, Inflammation                                          1 (2%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   Bone                                               (50)         (50)         (50)         (49)                                   
      Fibrous Osteodystrophy                                        1 (2%)                                                          
      Hyperostosis                                     2 (4%)       5 (10%)      5 (10%)      1 (2%)                                
      Turbinate, Hyperostosis                                       2 (4%)       2 (4%)       1 (2%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    6                                                              
NTP Experiment-Test: 05210-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 03/14/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:45:33  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS FEMALE                   CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (50)         (50)         (50)         (49)                                   
      Hemorrhage                                       1 (2%)                                 1 (2%)                                
      Hydrocephalus                                                 1 (2%)                    1 (2%)                                
      Necrosis                                         1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Larynx                                             (45)         (43)         (44)         (45)                                   
      Infiltration Cellular, Lymphocyte                             3 (7%)       1 (2%)                                             
      Inflammation                                                  2 (5%)       1 (2%)       2 (4%)                                
      Metaplasia, Squamous                             1 (2%)                                                                       
      Respiratory Epithelium, Hyperplasia                                        1 (2%)       2 (4%)                                
      Respiratory Epithelium, Metaplasia, Squamous     1 (2%)       1 (2%)                    2 (4%)                                
   Lung                                               (50)         (50)         (50)         (49)                                   
      Congestion                                       5 (10%)                   1 (2%)                                             
      Edema                                                         1 (2%)       1 (2%)                                             
      Fibrosis                                         1 (2%)       1 (2%)       1 (2%)                                             
      Hemorrhage                                       1 (2%)       2 (4%)       2 (4%)                                             
      Infiltration Cellular, Histiocyte                2 (4%)       3 (6%)       1 (2%)       3 (6%)                                
      Inflammation, Chronic                            2 (4%)                                 3 (6%)                                
      Inflammation, Chronic Active                                               1 (2%)                                             
      Inflammation, Granulomatous                      1 (2%)       1 (2%)       1 (2%)       2 (4%)                                
      Alveolar Epithelium, Hyperplasia                 1 (2%)       5 (10%)      2 (4%)       5 (10%)                               
   Nose                                               (50)         (50)         (50)         (49)                                   
      Angiectasis                                                                1 (2%)                                             
      Congestion                                       1 (2%)                                                                       
      Foreign Body                                     4 (8%)       1 (2%)                    1 (2%)                                
      Infiltration Cellular, Lymphocyte                                                       1 (2%)                                
      Inflammation                                    10 (20%)     10 (20%)      5 (10%)      1 (2%)                                
      Necrosis                                                                   1 (2%)                                             
      Thrombosis                                       1 (2%)                                                                       
      Glands, Cyst                                                               1 (2%)                                             
      Glands, Hyperplasia                                           1 (2%)       2 (4%)       1 (2%)                                
      Goblet Cell, Hyperplasia                                                                1 (2%)                                
      Nasolacrimal Duct, Inflammation                  2 (4%)       1 (2%)                                                          
      Nasolacrimal Duct, Metaplasia, Squamous          1 (2%)                                                                       
      Respiratory Epithelium, Hyperplasia              6 (12%)      7 (14%)      5 (10%)                                            
      Respiratory Epithelium, Metaplasia, Squamous                  1 (2%)                                                          
      Respiratory Epithelium, Ulcer                                 2 (4%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    7                                                              
NTP Experiment-Test: 05210-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 03/14/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:45:33  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS FEMALE                   CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   Eye                                                (1)                       (3)          (1)                                    
      Lens, Cataract                                   1 (100%)                  2 (67%)      1 (100%)                              
      Retina, Degeneration                             1 (100%)                               1 (100%)                              
   Harderian Gland                                                                           (1)                                    
      Inflammation                                                                            1 (100%)                              
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (50)         (50)         (50)         (49)                                   
      Cyst                                             1 (2%)       1 (2%)                    4 (8%)                                
      Infarct                                          1 (2%)                    1 (2%)                                             
      Mineralization                                   8 (16%)     11 (22%)      7 (14%)                                            
      Necrosis                                                                   1 (2%)                                             
      Nephropathy                                     38 (76%)     42 (84%)     43 (86%)     46 (94%)                               
      Pigmentation                                     4 (8%)      10 (20%)      8 (16%)      3 (6%)                                
      Arteriole, Inflammation                          1 (2%)                                                                       
      Renal Tubule, Degeneration                                                 1 (2%)                                             
      Renal Tubule, Hyperplasia                                     1 (2%)       3 (6%)       3 (6%)                                
      Transitional Epithelium, Hyperplasia                                                    2 (4%)                                
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    8                                                              
NTP Experiment-Test: 05210-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 03/14/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:45:33  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS MALE                     CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
DISPOSITION SUMMARY                                                                                                                 
  Animals Initially In Study                          50           50           50           50                                     
  Early Deaths                                                                                                                      
    Natural Death                                      7           16           11           22                                     
    Moribund Sacrifice                                28           20           26           26                                     
  Survivors                                                                                                                         
    Terminal Sacrifice                                15           14           13            2                                     
  Animals Examined Microscopically                    50           50           50           50                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Intestine Large, Colon                             (50)         (48)         (48)         (48)                                   
      Hemorrhage                                                    1 (2%)                                                          
      Inflammation                                                  1 (2%)                                                          
      Mineralization                                   1 (2%)       1 (2%)                    1 (2%)                                
   Intestine Large, Rectum                            (48)         (49)         (48)         (48)                                   
      Thrombosis                                                                 1 (2%)                                             
   Intestine Large, Cecum                             (46)         (44)         (46)         (39)                                   
      Inflammation                                     1 (2%)       2 (5%)                    1 (3%)                                
      Mineralization                                                                          1 (3%)                                
      Necrosis                                                      1 (2%)                                                          
      Ulcer                                            1 (2%)                                                                       
   Intestine Small, Duodenum                          (48)         (48)         (50)         (50)                                   
      Mineralization                                   1 (2%)                                                                       
      Necrosis                                                                   1 (2%)                                             
   Intestine Small, Jejunum                           (42)         (39)         (44)         (34)                                   
      Inflammation                                                                            1 (3%)                                
   Intestine Small, Ileum                             (45)         (44)         (45)         (37)                                   
      Inflammation                                                                            1 (3%)                                
   Liver                                              (50)         (50)         (50)         (49)                                   
      Angiectasis                                                                2 (4%)       1 (2%)                                
      Basophilic Focus                                 6 (12%)      5 (10%)      2 (4%)       4 (8%)                                
      Clear Cell Focus                                 2 (4%)       3 (6%)       3 (6%)                                             
      Cyst                                                          1 (2%)                                                          
      Degeneration                                     1 (2%)                                                                       
      Degeneration, Cystic                            15 (30%)     12 (24%)     19 (38%)     30 (61%)                               
      Eosinophilic Focus                               5 (10%)     11 (22%)      4 (8%)       9 (18%)                               
      Fibrosis                                                      3 (6%)                                                          
      Hemorrhage                                                    2 (4%)                                                          
      Hepatodiaphragmatic Nodule                                    1 (2%)                    1 (2%)                                
      Inflammation, Chronic                            1 (2%)       1 (2%)       1 (2%)                                             
      Inflammation, Chronic Active                                  1 (2%)                                                          
      Mineralization                                                                          1 (2%)                                
      Mixed Cell Focus                                 1 (2%)       2 (4%)                                                          
      Necrosis                                         2 (4%)       4 (8%)                    8 (16%)                               
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    9                                                              
NTP Experiment-Test: 05210-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 03/14/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:45:33  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS MALE                     CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ALIMENTARY SYSTEM - CONT                                                                                                            
      Pigmentation                                     1 (2%)                                                                       
      Thrombosis                                                                 1 (2%)                                             
      Vacuolization Cytoplasmic                        8 (16%)     10 (20%)      7 (14%)      4 (8%)                                
      Bile Duct, Hyperplasia                                                                  1 (2%)                                
      Bile Duct, Inflammation, Suppurative                          1 (2%)                                                          
      Kupffer Cell, Hyperplasia                                                  1 (2%)                                             
   Mesentery                                          (4)          (5)          (3)          (3)                                    
      Inflammation                                                  1 (20%)                                                         
      Fat, Necrosis                                    3 (75%)      4 (80%)      2 (67%)      3 (100%)                              
   Pancreas                                           (50)         (49)         (50)         (50)                                   
      Inflammation                                                  2 (4%)       1 (2%)       1 (2%)                                
      Acinus, Atrophy                                 24 (48%)     21 (43%)     20 (40%)     18 (36%)                               
      Acinus, Hyperplasia                              4 (8%)                    1 (2%)                                             
      Artery, Degeneration                                          1 (2%)       1 (2%)                                             
      Artery, Inflammation                                          1 (2%)                                                          
      Artery, Mineralization                                        1 (2%)                                                          
   Stomach, Forestomach                               (50)         (50)         (50)         (50)                                   
      Hyperkeratosis                                   1 (2%)                    1 (2%)                                             
      Hyperplasia                                      8 (16%)      5 (10%)      8 (16%)      8 (16%)                               
      Inflammation                                     1 (2%)       1 (2%)       3 (6%)       3 (6%)                                
      Mineralization                                   2 (4%)       1 (2%)       1 (2%)       5 (10%)                               
      Ulcer                                            9 (18%)      9 (18%)      9 (18%)     10 (20%)                               
   Stomach, Glandular                                 (50)         (49)         (50)         (50)                                   
      Degeneration                                                               1 (2%)                                             
      Degeneration, Cystic                                                                    1 (2%)                                
      Inflammation                                     2 (4%)       1 (2%)       3 (6%)       1 (2%)                                
      Mineralization                                   4 (8%)       4 (8%)       3 (6%)      18 (36%)                               
      Necrosis                                         5 (10%)      2 (4%)       2 (4%)                                             
      Ulcer                                                         2 (4%)                    2 (4%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Blood Vessel                                       (50)         (50)         (50)         (50)                                   
      Mineralization                                                                          1 (2%)                                
      Aorta, Inflammation                                                        1 (2%)       1 (2%)                                
      Aorta, Mineralization                            2 (4%)       2 (4%)       4 (8%)      14 (28%)                               
   Heart                                              (50)         (50)         (50)         (50)                                   
      Cardiomyopathy                                  26 (52%)     21 (42%)     15 (30%)     30 (60%)                               
      Inflammation                                                               1 (2%)                                             
      Mineralization                                   2 (4%)       1 (2%)                    7 (14%)                               
      Atrium, Thrombosis                               5 (10%)      7 (14%)      7 (14%)                                            
      Valve, Fibrosis                                  1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   10                                                              
NTP Experiment-Test: 05210-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 03/14/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:45:33  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS MALE                     CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Cortex                                     (50)         (50)         (50)         (50)                                   
      Cytoplasmic Alteration                                        1 (2%)                                                          
      Degeneration                                                               1 (2%)                                             
      Degeneration, Cystic                             1 (2%)       2 (4%)       1 (2%)       3 (6%)                                
      Hyperplasia                                      1 (2%)                    1 (2%)       2 (4%)                                
      Hypertrophy                                                                             1 (2%)                                
      Necrosis                                                                   1 (2%)       2 (4%)                                
      Pigmentation                                     1 (2%)                                                                       
      Vacuolization Cytoplasmic                       13 (26%)     18 (36%)     16 (32%)     11 (22%)                               
      Bilateral, Atrophy                               1 (2%)                                                                       
      Capsule, Inflammation                                                                   1 (2%)                                
   Adrenal Medulla                                    (50)         (50)         (49)         (48)                                   
      Hyperplasia                                     10 (20%)      7 (14%)     13 (27%)      8 (17%)                               
      Necrosis                                                                                1 (2%)                                
      Bilateral, Hyperplasia                           2 (4%)       2 (4%)       1 (2%)       4 (8%)                                
   Islets, Pancreatic                                 (50)         (50)         (50)         (50)                                   
      Hyperplasia                                      2 (4%)       5 (10%)      4 (8%)                                             
   Parathyroid Gland                                  (45)         (46)         (46)         (46)                                   
      Fibrosis                                                                   1 (2%)                                             
      Hyperplasia                                     12 (27%)      6 (13%)     16 (35%)     35 (76%)                               
   Pituitary Gland                                    (49)         (50)         (50)         (45)                                   
      Pars Distalis, Angiectasis                       5 (10%)     11 (22%)      5 (10%)      4 (9%)                                
      Pars Distalis, Cyst                              1 (2%)       6 (12%)      5 (10%)      4 (9%)                                
      Pars Distalis, Degeneration                                                1 (2%)                                             
      Pars Distalis, Hemorrhage                                     1 (2%)       1 (2%)                                             
      Pars Distalis, Hyperplasia                      12 (24%)     11 (22%)     12 (24%)     12 (27%)                               
      Pars Distalis, Necrosis                                                    1 (2%)                                             
      Pars Distalis, Pigmentation                      1 (2%)                    2 (4%)                                             
      Pars Intermedia, Angiectasis                     1 (2%)                                                                       
   Thyroid Gland                                      (50)         (49)         (50)         (50)                                   
      Cyst                                                          1 (2%)                                                          
      C-Cell, Hyperplasia                              6 (12%)      5 (10%)      5 (10%)                                            
      Follicle, Cyst                                   1 (2%)       1 (2%)                    2 (4%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Epididymis                                         (50)         (50)         (50)         (50)                                   
      Granuloma Sperm                                               1 (2%)       1 (2%)                                             
      Inflammation                                                  1 (2%)       1 (2%)       1 (2%)                                
      Mineralization                                                                          1 (2%)                                
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   11                                                              
NTP Experiment-Test: 05210-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 03/14/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:45:33  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS MALE                     CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
GENITAL SYSTEM - CONT                                                                                                               
   Preputial Gland                                    (49)         (50)         (49)         (50)                                   
      Atrophy                                                                    1 (2%)                                             
      Hyperplasia                                      2 (4%)       2 (4%)                    1 (2%)                                
      Inflammation                                    19 (39%)      7 (14%)      8 (16%)     10 (20%)                               
   Prostate                                           (50)         (50)         (50)         (50)                                   
      Hyperplasia                                      1 (2%)       1 (2%)       1 (2%)                                             
      Infiltration Cellular, Lymphocyte                             1 (2%)                                                          
      Inflammation                                    11 (22%)     29 (58%)     22 (44%)     25 (50%)                               
   Seminal Vesicle                                    (49)         (49)         (50)         (50)                                   
      Inflammation                                                  1 (2%)       1 (2%)                                             
      Mineralization                                   1 (2%)                                                                       
   Testes                                             (50)         (50)         (50)         (50)                                   
      Atrophy                                         10 (20%)      7 (14%)     10 (20%)      6 (12%)                               
      Degeneration                                                  1 (2%)                    1 (2%)                                
      Hemorrhage                                       1 (2%)                                                                       
      Mineralization                                                                          2 (4%)                                
      Arteriole, Inflammation                                       1 (2%)       1 (2%)                                             
      Bilateral, Atrophy                               9 (18%)      7 (14%)      5 (10%)      4 (8%)                                
      Bilateral, Necrosis                                                        1 (2%)                                             
      Interstitial Cell, Hyperplasia                  14 (28%)     19 (38%)     12 (24%)      8 (16%)                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Bone Marrow                                        (49)         (49)         (50)         (50)                                   
      Atrophy                                                                    1 (2%)       1 (2%)                                
      Hemorrhage                                       1 (2%)                    2 (4%)       4 (8%)                                
      Hyperplasia                                      7 (14%)     16 (33%)      9 (18%)     19 (38%)                               
      Inflammation                                                  1 (2%)                                                          
      Myelofibrosis                                    3 (6%)                                 5 (10%)                               
      Myeloid Cell, Atrophy                            1 (2%)                                                                       
   Lymph Node                                         (9)          (8)          (9)          (14)                                   
      Hemorrhage                                                                 1 (11%)                                            
      Lumbar, Hemorrhage                                            1 (13%)                                                         
      Lumbar, Hyperplasia, Plasma Cell                              1 (13%)                                                         
      Pancreatic, Fibrosis                                                       1 (11%)                                            
      Pancreatic, Pigmentation                                                   1 (11%)                                            
      Renal, Ectasia                                                             2 (22%)      1 (7%)                                
      Renal, Hemorrhage                                                          1 (11%)      8 (57%)                               
      Renal, Hyperplasia, Lymphoid                                                            1 (7%)                                
      Renal, Hyperplasia, Plasma Cell                                            1 (11%)      1 (7%)                                
      Renal, Infiltration Cellular, Histiocyte                      1 (13%)                                                         
      Renal, Pigmentation                                                        1 (11%)      2 (14%)                               
   Lymph Node, Bronchial                              (44)         (34)         (39)         (28)                                   
      Ectasia                                                                    1 (3%)                                             
      Hemorrhage                                       7 (16%)      4 (12%)      4 (10%)      7 (25%)                               
      Infiltration Cellular, Histiocyte                                          2 (5%)                                             
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   12                                                              
NTP Experiment-Test: 05210-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 03/14/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:45:33  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS MALE                     CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
HEMATOPOIETIC SYSTEM - CONT                                                                                                         
      Pigmentation                                     3 (7%)       3 (9%)                    5 (18%)                               
   Lymph Node, Mandibular                             (47)         (48)         (49)         (50)                                   
      Atrophy                                                       1 (2%)                                                          
      Hemorrhage                                       1 (2%)                                 1 (2%)                                
      Hyperplasia, Plasma Cell                         4 (9%)       1 (2%)       1 (2%)       4 (8%)                                
      Inflammation                                                               1 (2%)                                             
      Pigmentation                                     1 (2%)                                                                       
   Lymph Node, Mesenteric                             (49)         (50)         (50)         (50)                                   
      Atrophy                                                       1 (2%)                                                          
      Ectasia                                                                    1 (2%)                                             
      Hemorrhage                                       3 (6%)       5 (10%)      4 (8%)       8 (16%)                               
      Inflammation                                                               1 (2%)       1 (2%)                                
   Lymph Node, Mediastinal                            (48)         (48)         (50)         (47)                                   
      Edema                                            1 (2%)       1 (2%)                    3 (6%)                                
      Hemorrhage                                      12 (25%)     10 (21%)     10 (20%)     17 (36%)                               
      Hyperplasia, Plasma Cell                         1 (2%)       1 (2%)                                                          
      Infiltration Cellular, Histiocyte                2 (4%)       1 (2%)                    1 (2%)                                
      Inflammation                                                               1 (2%)                                             
      Pigmentation                                     9 (19%)      8 (17%)      7 (14%)      7 (15%)                               
   Spleen                                             (50)         (49)         (50)         (50)                                   
      Atrophy                                                                                 2 (4%)                                
      Congestion                                       1 (2%)       1 (2%)                                                          
      Depletion Cellular                                            2 (4%)       3 (6%)       4 (8%)                                
      Fibrosis                                         3 (6%)       1 (2%)       4 (8%)       1 (2%)                                
      Hematopoietic Cell Proliferation                 3 (6%)       4 (8%)       1 (2%)       2 (4%)                                
      Inflammation, Chronic                                                      1 (2%)                                             
      Necrosis                                         2 (4%)                                 2 (4%)                                
      Pigmentation                                                  1 (2%)                                                          
      Red Pulp, Depletion Cellular                                               1 (2%)                                             
   Thymus                                             (46)         (44)         (46)         (44)                                   
      Cyst                                                                                    1 (2%)                                
      Hemorrhage                                                    1 (2%)                    1 (2%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Mammary Gland                                      (46)         (47)         (46)         (49)                                   
      Fibrosis                                                                   1 (2%)                                             
      Galactocele                                     11 (24%)     11 (23%)     11 (24%)      9 (18%)                               
      Hyperplasia                                      3 (7%)       3 (6%)       4 (9%)       3 (6%)                                
      Inflammation                                     1 (2%)       2 (4%)       1 (2%)                                             
      Mineralization                                                                          1 (2%)                                
      Pigmentation                                     1 (2%)       4 (9%)       2 (4%)       6 (12%)                               
   Skin                                               (50)         (50)         (50)         (50)                                   
      Cyst Epithelial Inclusion                        1 (2%)       4 (8%)       2 (4%)                                             
      Hyperkeratosis                                   1 (2%)                                 1 (2%)                                
      Inflammation                                                                            1 (2%)                                
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   13                                                              
NTP Experiment-Test: 05210-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 03/14/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:45:33  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS MALE                     CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
INTEGUMENTARY SYSTEM - CONT                                                                                                         
      Inflammation, Granulomatous                                   1 (2%)                                                          
      Epidermis, Hyperplasia                                                     1 (2%)                                             
      Subcutaneous Tissue, Inflammation                             2 (4%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   Bone                                               (49)         (50)         (50)         (50)                                   
      Fibrous Osteodystrophy                           1 (2%)       1 (2%)       5 (10%)      9 (18%)                               
      Hyperostosis                                                               2 (4%)                                             
      Turbinate, Hyperostosis                          1 (2%)       1 (2%)                    1 (2%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (50)         (50)         (50)         (50)                                   
      Hemorrhage                                                    1 (2%)                                                          
      Hydrocephalus                                    1 (2%)       2 (4%)       1 (2%)                                             
      Mineralization                                                             1 (2%)                                             
      Necrosis                                         2 (4%)       1 (2%)       3 (6%)       1 (2%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Larynx                                             (40)         (44)         (41)         (35)                                   
      Foreign Body                                                               1 (2%)                                             
      Infiltration Cellular, Lymphocyte                1 (3%)       1 (2%)       1 (2%)       1 (3%)                                
      Inflammation                                     1 (3%)       3 (7%)       3 (7%)       1 (3%)                                
      Necrosis                                                      1 (2%)                                                          
      Respiratory Epithelium, Hyperplasia              1 (3%)       4 (9%)       1 (2%)       1 (3%)                                
      Respiratory Epithelium, Metaplasia, Squamous     1 (3%)       1 (2%)       1 (2%)       2 (6%)                                
   Lung                                               (50)         (50)         (50)         (50)                                   
      Congestion                                       1 (2%)       2 (4%)                    6 (12%)                               
      Edema                                            1 (2%)                                 6 (12%)                               
      Fibrosis                                                                   1 (2%)       1 (2%)                                
      Foreign Body                                                               1 (2%)                                             
      Hemorrhage                                                    2 (4%)       1 (2%)       8 (16%)                               
      Infiltration Cellular, Histiocyte                2 (4%)       1 (2%)                                                          
      Inflammation, Acute                                           1 (2%)       1 (2%)       1 (2%)                                
      Inflammation, Chronic                            1 (2%)                    1 (2%)       2 (4%)                                
      Inflammation, Chronic Active                     2 (4%)       3 (6%)       2 (4%)       7 (14%)                               
      Inflammation, Granulomatous                      1 (2%)       1 (2%)                                                          
      Mineralization                                   1 (2%)       1 (2%)                    3 (6%)                                
      Alveolar Epithelium, Hyperplasia                 2 (4%)       2 (4%)       1 (2%)       2 (4%)                                
      Artery, Mineralization                                                                  1 (2%)                                
      Goblet Cell, Hyperplasia                                                   1 (2%)                                             
      Interstitium, Fibrosis                                        1 (2%)                                                          
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   14                                                              
NTP Experiment-Test: 05210-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 03/14/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:45:33  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS MALE                     CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
RESPIRATORY SYSTEM - CONT                                                                                                           
      Interstitium, Inflammation                                                              1 (2%)                                
   Nose                                               (49)         (49)         (50)         (50)                                   
      Angiectasis                                                                1 (2%)                                             
      Congestion                                                                              1 (2%)                                
      Foreign Body                                     2 (4%)       2 (4%)       2 (4%)       1 (2%)                                
      Infiltration Cellular, Lymphocyte                             1 (2%)                                                          
      Inflammation                                     8 (16%)      8 (16%)      9 (18%)      9 (18%)                               
      Necrosis                                                                                1 (2%)                                
      Glands, Cyst                                                  1 (2%)                                                          
      Goblet Cell, Hyperplasia                         2 (4%)                    1 (2%)                                             
      Nasolacrimal Duct, Inflammation                  1 (2%)       1 (2%)       1 (2%)                                             
      Olfactory Epithelium, Inflammation                                                      1 (2%)                                
      Olfactory Epithelium, Metaplasia                                                        1 (2%)                                
      Respiratory Epithelium, Hyperplasia              9 (18%)      7 (14%)      9 (18%)      6 (12%)                               
      Respiratory Epithelium, Inflammation             1 (2%)                                 3 (6%)                                
      Respiratory Epithelium, Metaplasia, Squamous     1 (2%)                                 1 (2%)                                
      Respiratory Epithelium, Ulcer                    1 (2%)                    1 (2%)                                             
   Trachea                                            (50)         (50)         (50)         (50)                                   
      Mineralization                                                                          1 (2%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   Eye                                                (1)          (1)                                                              
      Lens, Cataract                                   1 (100%)                                                                     
      Retina, Degeneration                             1 (100%)                                                                     
   Zymbal's Gland                                     (1)                       (1)          (1)                                    
      Cyst                                                                                    1 (100%)                              
      Hyperplasia                                                                             1 (100%)                              
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (50)         (50)         (50)         (50)                                   
      Cyst                                                          4 (8%)       1 (2%)      10 (20%)                               
      Hemorrhage                                                    1 (2%)                                                          
      Infarct                                          2 (4%)                                 1 (2%)                                
      Inflammation                                                  1 (2%)                                                          
      Mineralization                                   1 (2%)       1 (2%)       1 (2%)       9 (18%)                               
      Necrosis                                         1 (2%)                                 1 (2%)                                
      Nephropathy                                     47 (94%)     43 (86%)     47 (94%)     48 (96%)                               
      Pigmentation                                     9 (18%)      6 (12%)      9 (18%)      2 (4%)                                
      Renal Tubule, Hyperplasia                        2 (4%)       2 (4%)       4 (8%)      12 (24%)                               
      Transitional Epithelium, Hyperplasia            12 (24%)     14 (28%)     15 (30%)     34 (68%)                               
   Urinary Bladder                                    (49)         (49)         (50)         (49)                                   
      Hemorrhage                                       1 (2%)       2 (4%)                    1 (2%)                                
      Inflammation                                     1 (2%)       3 (6%)       1 (2%)                                             
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   15                                                              
NTP Experiment-Test: 05210-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 03/14/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:45:33  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS MALE                     CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
URINARY SYSTEM - CONT                                                                                                               
      Necrosis                                                      1 (2%)                                                          
      Transitional Epithelium, Hyperplasia                          2 (4%)       1 (2%)                                             
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   16                                                              
                             ------------------------------------------------------------                                           
                             ----------              END OF REPORT             ----------                                           
                             ------------------------------------------------------------