Skip to Main Navigation
Skip to Page Content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it's official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you're on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Share This:
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             ----------                                           
                             ------------------------------------------------------------