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TDMS Study 05210-04 Pathology Tables

NTP Experiment-Test: 05210-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 04/23/96
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 08:53:41

                                                           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: 05210-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 04/23/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 08:53:41  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE FEMALE                        CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
DISPOSITION SUMMARY                                                                                                                 
  Animals Initially In Study                          50           50           50           50                                     
  Early Deaths                                                                                                                      
    Moribund Sacrifice                                 5            6            1            4                                     
    Natural Death                                      9            6            8            9                                     
    Accidently Killed                                  1                         1                                                  
  Survivors                                                                                                                         
    Terminal Sacrifice                                34           38           40           37                                     
    Natural Death                                      1                                                                            
  Animals Examined Microscopically                    50           50           50           50                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Gallbladder                                        (44)         (44)         (44)         (46)                                   
      Infiltration Cellular                            1 (2%)                                                                       
   Intestine Small, Duodenum                          (45)         (48)         (47)         (46)                                   
      Ulcer                                                                                   1 (2%)                                
   Intestine Small, Jejunum                           (46)         (46)         (46)         (45)                                   
      Peyer's Patch, Hyperplasia                                                              1 (2%)                                
   Intestine Small, Ileum                             (47)         (47)         (47)         (46)                                   
      Peyer's Patch, Hyperplasia                                    1 (2%)                                                          
   Liver                                              (50)         (50)         (50)         (50)                                   
      Angiectasis                                                   1 (2%)                                                          
      Basophilic Focus                                 3 (6%)                    4 (8%)       3 (6%)                                
      Clear Cell Focus                                 1 (2%)                    1 (2%)                                             
      Eosinophilic Focus                               5 (10%)      7 (14%)      6 (12%)     22 (44%)                               
      Hemorrhage                                                                 1 (2%)       1 (2%)                                
      Hepatodiaphragmatic Nodule                                                 2 (4%)                                             
      Infiltration Cellular                            3 (6%)                                                                       
      Inflammation                                     1 (2%)       3 (6%)       1 (2%)       1 (2%)                                
      Mineralization                                                                          1 (2%)                                
      Mixed Cell Focus                                                           1 (2%)       1 (2%)                                
      Necrosis                                         1 (2%)       4 (8%)       3 (6%)       4 (8%)                                
      Pigmentation, Hemosiderin                        1 (2%)       1 (2%)                                                          
      Bile Duct, Cyst                                                                         1 (2%)                                
      Hepatocyte, Hypertrophy                                                                 1 (2%)                                
      Hepatocyte, Necrosis                                          1 (2%)                                                          
      Hepatocyte, Syncytial Alteration                                           1 (2%)                                             
      Hepatocyte, Vacuolization Cytoplasmic            2 (4%)                    2 (4%)       1 (2%)                                
      Serosa, Inflammation                                                                    1 (2%)                                
   Mesentery                                          (2)                                                                           
      Fat, Necrosis                                    2 (100%)                                                                     
   Pancreas                                           (50)         (50)         (50)         (49)                                   
      Angiectasis                                                   1 (2%)                                                          
      Atrophy                                                       2 (4%)                                                          
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    2                                                              
NTP Experiment-Test: 05210-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 04/23/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 08:53:41  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE FEMALE                        CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ALIMENTARY SYSTEM - CONT                                                                                                            
      Cyst                                                          1 (2%)                                                          
      Degeneration                                                  1 (2%)                                                          
      Fibrosis                                                      1 (2%)                                                          
      Infiltration Cellular                            7 (14%)     12 (24%)     12 (24%)     10 (20%)                               
      Necrosis                                                      1 (2%)                                                          
      Acinus, Hyperplasia                              1 (2%)                                                                       
      Duct, Cyst                                                                              1 (2%)                                
   Salivary Glands                                    (50)         (50)         (50)         (50)                                   
      Atrophy                                                       1 (2%)                                                          
      Infiltration Cellular                           30 (60%)     32 (64%)     33 (66%)     30 (60%)                               
   Stomach, Forestomach                               (50)         (49)         (48)         (50)                                   
      Hyperplasia                                                                             2 (4%)                                
      Ulcer                                                                      1 (2%)                                             
      Epithelium, Cyst                                                                        2 (4%)                                
      Epithelium, Hyperplasia                                       2 (4%)                    1 (2%)                                
   Stomach, Glandular                                 (50)         (49)         (48)         (50)                                   
      Infiltration Cellular                            1 (2%)                                                                       
      Glands, Cyst                                     1 (2%)                                                                       
      Glands, Hyperplasia                                                                     1 (2%)                                
      Serosa, Infiltration Cellular                                                           1 (2%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Heart                                              (50)         (49)         (50)         (50)                                   
      Cardiomyopathy                                  10 (20%)     23 (47%)     23 (46%)     15 (30%)                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Cortex                                     (47)         (50)         (50)         (49)                                   
      Accessory Adrenal Cortical Nodule                2 (4%)       1 (2%)                                                          
      Degeneration                                    12 (26%)      4 (8%)       4 (8%)       5 (10%)                               
      Hemorrhage                                       2 (4%)       1 (2%)       2 (4%)       3 (6%)                                
      Hyperplasia                                      3 (6%)       5 (10%)      3 (6%)       3 (6%)                                
      Infiltration Cellular                                         2 (4%)                                                          
      Inflammation                                                  3 (6%)                                                          
      Necrosis                                         1 (2%)                                                                       
      Vacuolization Cytoplasmic                        1 (2%)                                                                       
      Capsule, Hyperplasia                            46 (98%)     49 (98%)     48 (96%)     46 (94%)                               
   Adrenal Medulla                                    (47)         (50)         (50)         (49)                                   
      Hemorrhage                                       1 (2%)                                                                       
      Hyperplasia                                      2 (4%)       3 (6%)                    1 (2%)                                
   Islets, Pancreatic                                 (50)         (50)         (50)         (49)                                   
      Hyperplasia                                                   2 (4%)       2 (4%)                                             
      Infiltration Cellular                            1 (2%)                    2 (4%)                                             
   Parathyroid Gland                                  (26)         (24)         (34)         (27)                                   
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    3                                                              
NTP Experiment-Test: 05210-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 04/23/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 08:53:41  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE FEMALE                        CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ENDOCRINE SYSTEM - CONT                                                                                                             
      Infiltration Cellular                                         1 (4%)                                                          
   Pituitary Gland                                    (48)         (49)         (47)         (49)                                   
      Pars Distalis, Angiectasis                                                 4 (9%)       2 (4%)                                
      Pars Distalis, Cyst                                           1 (2%)                                                          
      Pars Distalis, Hemorrhage                        3 (6%)                    1 (2%)       1 (2%)                                
      Pars Distalis, Hyperplasia                      10 (21%)     12 (24%)     23 (49%)     22 (45%)                               
      Pars Distalis, Necrosis                                                                 1 (2%)                                
      Pars Intermedia, Hyperplasia                     2 (4%)       1 (2%)                    1 (2%)                                
   Thyroid Gland                                      (50)         (50)         (50)         (50)                                   
      Infiltration Cellular                                                      1 (2%)                                             
      Follicle, Degeneration                           1 (2%)                                                                       
      Follicular Cell, Hyperplasia                    18 (36%)     23 (46%)     25 (50%)     35 (70%)                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   Tissue NOS                                         (1)          (6)          (4)          (1)                                    
      Fat, Necrosis                                                 4 (67%)      3 (75%)      1 (100%)                              
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Clitoral Gland                                     (41)         (47)         (48)         (48)                                   
      Atrophy                                                                    1 (2%)                                             
      Degeneration                                                                            1 (2%)                                
   Ovary                                              (49)         (50)         (49)         (49)                                   
      Angiectasis                                      2 (4%)       1 (2%)                                                          
      Atrophy                                                       1 (2%)       1 (2%)                                             
      Cyst                                             8 (16%)      8 (16%)     10 (20%)     10 (20%)                               
      Hemorrhage                                       1 (2%)                    1 (2%)                                             
      Infiltration Cellular                                                      2 (4%)                                             
      Mineralization                                                                          1 (2%)                                
   Uterus                                             (50)         (50)         (50)         (50)                                   
      Angiectasis                                                                1 (2%)                                             
      Degeneration                                     2 (4%)       1 (2%)                    1 (2%)                                
      Hemorrhage                                                                 1 (2%)       1 (2%)                                
      Infiltration Cellular                                                                   1 (2%)                                
      Inflammation                                     3 (6%)                                 1 (2%)                                
      Thrombosis                                                                 1 (2%)                                             
      Endometrium, Hyperplasia                        44 (88%)     46 (92%)     47 (94%)     46 (92%)                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    4                                                              
NTP Experiment-Test: 05210-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 04/23/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 08:53:41  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE FEMALE                        CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Bone Marrow                                        (48)         (50)         (50)         (50)                                   
      Hematopoietic Cell Proliferation                              1 (2%)                                                          
      Infiltration Cellular, Histiocyte                                                       1 (2%)                                
      Inflammation                                     1 (2%)                                                                       
      Myelofibrosis                                                                           2 (4%)                                
      Pigmentation, Hemosiderin                        3 (6%)       1 (2%)       1 (2%)       1 (2%)                                
      Myeloid Cell, Hyperplasia                        1 (2%)                                 1 (2%)                                
   Lymph Node                                         (3)          (7)          (2)          (5)                                    
      Iliac, Hyperplasia                                            1 (14%)                                                         
      Inguinal, Hyperplasia                                                                   1 (20%)                               
      Inguinal, Pigmentation, Hemosiderin              1 (33%)                                                                      
      Lumbar, Hyperplasia                              1 (33%)      2 (29%)                                                         
      Pancreatic, Hyperplasia                                                                 1 (20%)                               
      Renal, Hyperplasia                               1 (33%)                                                                      
      Renal, Necrosis                                               1 (14%)                                                         
   Lymph Node, Bronchial                              (32)         (40)         (29)         (38)                                   
      Hyperplasia                                                   2 (5%)       1 (3%)       2 (5%)                                
   Lymph Node, Mandibular                             (47)         (48)         (47)         (44)                                   
      Hyperplasia                                      1 (2%)       2 (4%)                    2 (5%)                                
   Lymph Node, Mesenteric                             (48)         (48)         (46)         (44)                                   
      Hematopoietic Cell Proliferation                 1 (2%)                                                                       
      Hyperplasia                                      4 (8%)       3 (6%)       3 (7%)       2 (5%)                                
      Inflammation                                                  2 (4%)                                                          
      Inflammation, Granulomatous                      1 (2%)       1 (2%)                                                          
      Necrosis                                                      1 (2%)                                                          
   Lymph Node, Mediastinal                            (34)         (42)         (41)         (31)                                   
      Hyperplasia                                      3 (9%)       4 (10%)                   2 (6%)                                
      Hyperplasia, Histiocytic                         1 (3%)                                                                       
   Spleen                                             (50)         (50)         (50)         (49)                                   
      Hematopoietic Cell Proliferation                 4 (8%)       7 (14%)      2 (4%)       1 (2%)                                
      Hyperplasia                                      1 (2%)                                                                       
      Necrosis                                                      1 (2%)                                                          
      Pigmentation, Hemosiderin                        4 (8%)       1 (2%)       1 (2%)       4 (8%)                                
      Lymphoid Follicle, Hyperplasia                   9 (18%)      5 (10%)      1 (2%)       3 (6%)                                
   Thymus                                             (42)         (44)         (45)         (46)                                   
      Atrophy                                          5 (12%)      5 (11%)      5 (11%)      6 (13%)                               
      Thymocyte, Hyperplasia                           1 (2%)       2 (5%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Mammary Gland                                      (49)         (50)         (48)         (49)                                   
      Galactocele                                                   1 (2%)       1 (2%)                                             
      Hyperplasia                                                   1 (2%)                                                          
   Skin                                               (50)         (50)         (49)         (50)                                   
      Fibrosis                                                                   1 (2%)                                             
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    5                                                              
NTP Experiment-Test: 05210-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 04/23/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 08:53:41  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE FEMALE                        CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
INTEGUMENTARY SYSTEM - CONT                                                                                                         
      Inflammation                                     1 (2%)                    2 (4%)                                             
      Necrosis                                         1 (2%)                                                                       
      Ulcer                                            1 (2%)                    2 (4%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   Bone                                               (49)         (50)         (50)         (50)                                   
      Arthrosis                                                                  1 (2%)                                             
      Fracture                                                      2 (4%)                                                          
      Periosteum, Femur, Inflammation                  1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (50)         (50)         (50)         (50)                                   
      Hemorrhage                                       2 (4%)                                                                       
      Mineralization                                  19 (38%)     17 (34%)     26 (52%)     25 (50%)                               
      Cerebellum, Atrophy                              1 (2%)                                                                       
      Cerebrum, Atrophy                                2 (4%)       1 (2%)       2 (4%)                                             
      Cerebrum, Gliosis                                                                       1 (2%)                                
      Cerebrum, Hemorrhage                                                                    1 (2%)                                
      Medulla, Atrophy                                 1 (2%)                                                                       
      Medulla, Hemorrhage                              1 (2%)                                                                       
      Meninges, Infiltration Cellular                               2 (4%)       1 (2%)                                             
   Spinal Cord                                        (1)                                                                           
      Hemorrhage                                       1 (100%)                                                                     
      Myelin, Degeneration                             1 (100%)                                                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Larynx                                             (49)         (49)         (47)         (48)                                   
      Degeneration                                                               1 (2%)                                             
      Infiltration Cellular                            1 (2%)                    1 (2%)       1 (2%)                                
      Glands, Degeneration                                          2 (4%)       2 (4%)       2 (4%)                                
      Glands, Inflammation                                                       1 (2%)                                             
   Lung                                               (50)         (50)         (49)         (50)                                   
      Hemorrhage                                       1 (2%)                    1 (2%)                                             
      Hyperplasia, Lymphoid                                         1 (2%)                                                          
      Infiltration Cellular, Histiocyte                1 (2%)                                                                       
      Alveolar Epithelium, Hyperplasia                              1 (2%)       3 (6%)       1 (2%)                                
      Alveolar Epithelium, Metaplasia                                                         1 (2%)                                
      Vein, Thrombosis                                 1 (2%)                                                                       
   Nose                                               (49)         (50)         (50)         (50)                                   
      Hemorrhage                                       1 (2%)                                                                       
      Inflammation                                     3 (6%)       2 (4%)       3 (6%)                                             
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    6                                                              
NTP Experiment-Test: 05210-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 04/23/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 08:53:41  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE FEMALE                        CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
RESPIRATORY SYSTEM - CONT                                                                                                           
      Nasolacrimal Duct, Inflammation                  1 (2%)                                                                       
      Respiratory Epithelium, Metaplasia, Squamous     2 (4%)                    1 (2%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (50)         (50)         (50)         (50)                                   
      Casts Protein                                    1 (2%)                                 1 (2%)                                
      Infiltration Cellular                                         1 (2%)                                                          
      Mineralization                                                                          1 (2%)                                
      Nephropathy                                     13 (26%)      7 (14%)      9 (18%)     21 (42%)                               
      Cortex, Cyst                                                               1 (2%)       1 (2%)                                
      Cortex, Metaplasia, Osseous                                   1 (2%)                                                          
   Urinary Bladder                                    (47)         (48)         (47)         (49)                                   
      Hemorrhage                                       1 (2%)                                                                       
      Infiltration Cellular                            4 (9%)       4 (8%)       4 (9%)       5 (10%)                               
      Inflammation                                     1 (2%)                                                                       
      Ulcer                                            1 (2%)                                                                       
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    7                                                              
NTP Experiment-Test: 05210-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 04/23/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 08:53:41  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE MALE                          CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
DISPOSITION SUMMARY                                                                                                                 
  Animals Initially In Study                          50           50           50           50                                     
  Early Deaths                                                                                                                      
    Moribund Sacrifice                                 6            2            5            6                                     
    Natural Death                                     15           12           13           13                                     
    Accidently Killed                                  1                                      1                                     
  Survivors                                                                                                                         
    Terminal Sacrifice                                28           36           31           30                                     
    Natural Death                                                                1                                                  
  Animals Examined Microscopically                    50           50           50           50                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Gallbladder                                        (33)         (39)         (37)         (38)                                   
      Epithelium, Hyperplasia                                                    1 (3%)                                             
   Intestine Small, Duodenum                          (45)         (48)         (43)         (45)                                   
      Parasite Metazoan                                                          1 (2%)                                             
      Epithelium, Hyperplasia                                                    1 (2%)       1 (2%)                                
   Intestine Small, Jejunum                           (44)         (46)         (44)         (43)                                   
      Cyst                                                          1 (2%)                                                          
      Epithelium, Dysplasia                                         1 (2%)                                                          
      Peyer's Patch, Hyperplasia                       1 (2%)       1 (2%)                                                          
   Intestine Small, Ileum                             (42)         (46)         (44)         (41)                                   
      Peyer's Patch, Hyperplasia                       1 (2%)                                                                       
   Liver                                              (50)         (50)         (50)         (50)                                   
      Angiectasis                                                                             1 (2%)                                
      Basophilic Focus                                 3 (6%)       3 (6%)       5 (10%)      4 (8%)                                
      Clear Cell Focus                                 5 (10%)      4 (8%)       7 (14%)      3 (6%)                                
      Cyst                                             1 (2%)       1 (2%)                                                          
      Eosinophilic Focus                               6 (12%)      8 (16%)      8 (16%)     12 (24%)                               
      Eosinophilic Focus, Multiple                     1 (2%)                                                                       
      Fibrosis                                                      1 (2%)                    1 (2%)                                
      Hemorrhage                                                                              2 (4%)                                
      Hepatodiaphragmatic Nodule                                                 1 (2%)                                             
      Inflammation, Chronic                                         2 (4%)                                                          
      Mineralization                                                             1 (2%)                                             
      Mixed Cell Focus                                 3 (6%)       2 (4%)                    1 (2%)                                
      Necrosis                                         7 (14%)      8 (16%)     10 (20%)     10 (20%)                               
      Thrombosis                                                                              1 (2%)                                
      Hepatocyte, Hyperplasia                                                                 1 (2%)                                
      Hepatocyte, Hypertrophy                          1 (2%)                                17 (34%)                               
      Hepatocyte, Necrosis                             1 (2%)       1 (2%)       3 (6%)      10 (20%)                               
      Hepatocyte, Syncytial Alteration                              5 (10%)      8 (16%)     23 (46%)                               
      Hepatocyte, Vacuolization Cytoplasmic            4 (8%)       2 (4%)       4 (8%)       3 (6%)                                
      Vein, Thrombosis                                 1 (2%)                    2 (4%)                                             
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    8                                                              
NTP Experiment-Test: 05210-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 04/23/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 08:53:41  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE MALE                          CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ALIMENTARY SYSTEM - CONT                                                                                                            
   Pancreas                                           (49)         (50)         (48)         (48)                                   
      Inflammation                                     1 (2%)                                                                       
      Acinus, Hyperplasia                                                                     1 (2%)                                
      Duct, Cyst                                       1 (2%)       1 (2%)                                                          
      Duct, Degeneration                                                                      1 (2%)                                
      Duct, Fibrosis                                   1 (2%)                                                                       
   Salivary Glands                                    (50)         (50)         (50)         (50)                                   
      Infiltration Cellular                           21 (42%)     26 (52%)     17 (34%)     20 (40%)                               
   Stomach, Forestomach                               (48)         (50)         (50)         (47)                                   
      Cyst                                                                                    1 (2%)                                
      Ulcer                                            1 (2%)                                                                       
      Epithelium, Hyperplasia                                                                 1 (2%)                                
      Serosa, Inflammation                                                                    1 (2%)                                
   Stomach, Glandular                                 (48)         (50)         (50)         (47)                                   
      Infiltration Cellular                            1 (2%)                                                                       
      Inflammation                                                               1 (2%)                                             
      Metaplasia                                       1 (2%)                                                                       
      Mineralization                                                             2 (4%)                                             
   Tongue                                                                                    (1)                                    
      Inflammation, Granulomatous                                                             1 (100%)                              
   Tooth                                                                        (1)          (1)                                    
      Developmental Malformation                                                 1 (100%)                                           
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Heart                                              (50)         (50)         (50)         (50)                                   
      Cardiomyopathy                                  18 (36%)     36 (72%)     29 (58%)     25 (50%)                               
      Inflammation                                     2 (4%)                                                                       
      Myocardium, Mineralization                       1 (2%)                                                                       
      Pericardium, Hyperplasia                         1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Cortex                                     (47)         (47)         (48)         (48)                                   
      Accessory Adrenal Cortical Nodule                1 (2%)                                                                       
      Degeneration                                     1 (2%)       2 (4%)       1 (2%)                                             
      Hemorrhage                                       1 (2%)                                 1 (2%)                                
      Hyperplasia                                     13 (28%)      8 (17%)      9 (19%)      4 (8%)                                
      Vacuolization Cytoplasmic                        1 (2%)                                                                       
      Capsule, Hyperplasia                            19 (40%)     22 (47%)     20 (42%)     17 (35%)                               
   Adrenal Medulla                                    (47)         (46)         (48)         (48)                                   
      Degeneration                                                               1 (2%)                                             
      Hyperplasia                                                                2 (4%)                                             
      Mineralization                                                             1 (2%)                                             
   Islets, Pancreatic                                 (49)         (50)         (48)         (48)                                   
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    9                                                              
NTP Experiment-Test: 05210-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 04/23/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 08:53:41  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE MALE                          CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ENDOCRINE SYSTEM - CONT                                                                                                             
      Degeneration                                                               1 (2%)                                             
      Hyperplasia                                      5 (10%)      5 (10%)      8 (17%)      1 (2%)                                
   Pituitary Gland                                    (44)         (45)         (45)         (47)                                   
      Pars Distalis, Cyst                                           1 (2%)       2 (4%)       1 (2%)                                
      Pars Distalis, Hyperplasia                       1 (2%)       1 (2%)       1 (2%)                                             
   Thyroid Gland                                      (50)         (50)         (50)         (50)                                   
      Follicle, Cyst                                                             1 (2%)                                             
      Follicular Cell, Hyperplasia                    21 (42%)     21 (42%)     29 (58%)     32 (64%)                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   Tissue NOS                                         (2)          (3)          (1)          (2)                                    
      Cyst                                                          1 (33%)                                                         
      Fat, Necrosis                                                 2 (67%)                   1 (50%)                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Epididymis                                         (49)         (50)         (50)         (50)                                   
      Atypia Cellular                                  1 (2%)       1 (2%)                                                          
      Cyst                                             1 (2%)                                                                       
      Degeneration                                                                            2 (4%)                                
      Fibrosis                                                      1 (2%)                                                          
      Granuloma Sperm                                  2 (4%)       1 (2%)       1 (2%)                                             
      Infiltration Cellular                                         1 (2%)                                                          
      Inflammation                                     1 (2%)                                                                       
      Mineralization                                   1 (2%)                                                                       
      Bilateral, Fibrosis                                                        1 (2%)                                             
   Penis                                              (1)          (2)                                                              
      Concretion                                                    1 (50%)                                                         
      Inflammation                                     1 (100%)     1 (50%)                                                         
   Preputial Gland                                    (48)         (49)         (48)         (49)                                   
      Cyst                                                                       1 (2%)                                             
      Degeneration                                     3 (6%)       3 (6%)       9 (19%)      6 (12%)                               
      Degeneration, Cystic                                          1 (2%)                                                          
      Fibrosis                                                                   1 (2%)                                             
      Hyperplasia                                      1 (2%)                    1 (2%)                                             
      Infiltration Cellular                            1 (2%)       5 (10%)      6 (13%)      4 (8%)                                
      Inflammation                                     6 (13%)     11 (22%)     11 (23%)     13 (27%)                               
      Mineralization                                                1 (2%)                                                          
      Necrosis                                                                   1 (2%)                                             
   Prostate                                           (46)         (49)         (50)         (50)                                   
      Atrophy                                          1 (2%)                                                                       
      Infiltration Cellular                            1 (2%)       2 (4%)       1 (2%)       2 (4%)                                
      Inflammation                                     6 (13%)      5 (10%)      5 (10%)      6 (12%)                               
   Seminal Vesicle                                    (49)         (50)         (50)         (50)                                   
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   10                                                              
NTP Experiment-Test: 05210-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 04/23/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 08:53:41  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE MALE                          CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
GENITAL SYSTEM - CONT                                                                                                               
      Atrophy                                          2 (4%)       1 (2%)       3 (6%)       1 (2%)                                
      Degeneration                                    19 (39%)     26 (52%)     16 (32%)     22 (44%)                               
      Inflammation                                     1 (2%)       1 (2%)       2 (4%)                                             
   Testes                                             (49)         (50)         (50)         (50)                                   
      Atrophy                                                       1 (2%)                    1 (2%)                                
      Mineralization                                                                          1 (2%)                                
      Germinal Epithelium, Atrophy                                  1 (2%)                                                          
      Germinal Epithelium, Degeneration                                                       1 (2%)                                
      Interstitial Cell, Hyperplasia                                1 (2%)                                                          
      Tunic, Fibrosis                                                            1 (2%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Bone Marrow                                        (50)         (50)         (50)         (50)                                   
      Hematopoietic Cell Proliferation                              1 (2%)                                                          
      Hyperplasia                                      1 (2%)                                                                       
      Pigmentation, Hemosiderin                        2 (4%)       2 (4%)                    1 (2%)                                
      Myeloid Cell, Hyperplasia                        2 (4%)       4 (8%)       9 (18%)      4 (8%)                                
   Lymph Node                                         (4)          (7)          (11)         (3)                                    
      Inguinal, Hyperplasia                            1 (25%)      1 (14%)                                                         
      Inguinal, Pigmentation                                        1 (14%)                                                         
      Lumbar, Congestion                                                         1 (9%)                                             
      Lumbar, Hyperplasia                              1 (25%)      4 (57%)      4 (36%)      2 (67%)                               
      Lumbar, Inflammation                                                       2 (18%)                                            
      Lumbar, Pigmentation                                          1 (14%)                   1 (33%)                               
      Renal, Congestion                                                          2 (18%)                                            
      Renal, Hyperplasia                                            3 (43%)      3 (27%)                                            
   Lymph Node, Mandibular                             (43)         (45)         (46)         (44)                                   
      Pigmentation, Hemosiderin                                     1 (2%)                    1 (2%)                                
   Lymph Node, Mesenteric                             (45)         (46)         (47)         (48)                                   
      Atrophy                                                                                 1 (2%)                                
      Congestion                                       1 (2%)       3 (7%)       1 (2%)       2 (4%)                                
      Hematopoietic Cell Proliferation                              3 (7%)                                                          
      Hyperplasia                                      1 (2%)       2 (4%)       3 (6%)                                             
      Inflammation                                                  2 (4%)                    1 (2%)                                
   Lymph Node, Mediastinal                            (24)         (25)         (27)         (25)                                   
      Hyperplasia                                      1 (4%)                                                                       
   Spleen                                             (50)         (50)         (49)         (49)                                   
      Atrophy                                          1 (2%)                                                                       
      Hematopoietic Cell Proliferation                 3 (6%)       4 (8%)       2 (4%)                                             
      Lymphoid Follicle, Atrophy                       2 (4%)                    1 (2%)       1 (2%)                                
      Lymphoid Follicle, Hyperplasia                                             2 (4%)                                             
   Thymus                                             (37)         (37)         (39)         (34)                                   
      Atrophy                                         18 (49%)     11 (30%)     20 (51%)     11 (32%)                               
      Cyst                                             1 (3%)                                                                       
____________________________________________________________________________________________________________________________________
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   11                                                              
NTP Experiment-Test: 05210-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 04/23/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 08:53:41  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE MALE                          CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Mammary Gland                                      (3)          (2)          (3)          (3)                                    
      Atrophy                                          1 (33%)      1 (50%)      2 (67%)      1 (33%)                               
   Skin                                               (50)         (50)         (50)         (50)                                   
      Cyst                                                          1 (2%)                                                          
      Infiltration Cellular, Melanocyte                             1 (2%)                                                          
      Inflammation                                     3 (6%)       6 (12%)      4 (8%)       3 (6%)                                
      Necrosis                                         1 (2%)                                                                       
      Ulcer                                            1 (2%)       5 (10%)      2 (4%)       3 (6%)                                
      Hair Follicle, Atrophy                                        1 (2%)                                                          
      Prepuce, Degeneration                                                      1 (2%)                                             
      Prepuce, Hyperplasia, Lymphoid                                             1 (2%)                                             
      Prepuce, Inflammation                                                      2 (4%)                                             
      Prepuce, Ulcer                                                             2 (4%)                                             
      Sebaceous Gland, Cyst                                         1 (2%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   Bone                                               (50)         (49)         (50)         (50)                                   
      Vertebra, Degeneration                           1 (2%)                                 1 (2%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (50)         (50)         (50)         (50)                                   
      Mineralization                                  21 (42%)     18 (36%)     19 (38%)     19 (38%)                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Larynx                                             (48)         (49)         (46)         (49)                                   
      Foreign Body                                                               1 (2%)                                             
      Hemorrhage                                                                              1 (2%)                                
      Infiltration Cellular                            1 (2%)       4 (8%)       4 (9%)                                             
      Glands, Degeneration                                          1 (2%)       3 (7%)       2 (4%)                                
      Glands, Inflammation                                          1 (2%)       2 (4%)                                             
   Lung                                               (50)         (50)         (50)         (50)                                   
      Congestion                                                                 1 (2%)                                             
      Hemorrhage                                                                              1 (2%)                                
      Infiltration Cellular, Histiocyte                2 (4%)                    1 (2%)       2 (4%)                                
      Inflammation                                     1 (2%)                                                                       
      Pigmentation, Hemosiderin                                                  1 (2%)                                             
      Thrombosis                                                                 1 (2%)                                             
      Alveolar Epithelium, Hyperplasia                 1 (2%)       5 (10%)      2 (4%)       4 (8%)                                
      Alveolar Epithelium, Metaplasia                               1 (2%)       2 (4%)       6 (12%)                               
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   12                                                              
NTP Experiment-Test: 05210-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 04/23/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 08:53:41  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE MALE                          CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
RESPIRATORY SYSTEM - CONT                                                                                                           
   Nose                                               (50)         (50)         (50)         (50)                                   
      Edema                                                                                   1 (2%)                                
      Hemorrhage                                       1 (2%)                                 1 (2%)                                
      Inflammation                                     7 (14%)      3 (6%)       4 (8%)       1 (2%)                                
      Polyp, Inflammatory                              2 (4%)       1 (2%)       2 (4%)                                             
      Nasolacrimal Duct, Inflammation                  3 (6%)                    1 (2%)       1 (2%)                                
      Respiratory Epithelium, Inflammation                                                    1 (2%)                                
      Respiratory Epithelium, Metaplasia, Squamous                  1 (2%)                                                          
   Trachea                                            (50)         (50)         (50)         (50)                                   
      Glands, Cyst                                                                            1 (2%)                                
      Glands, Hemorrhage                                                                      1 (2%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (50)         (50)         (50)         (50)                                   
      Degeneration                                     1 (2%)                                                                       
      Infarct                                          1 (2%)                                                                       
      Inflammation                                     3 (6%)       5 (10%)      5 (10%)      3 (6%)                                
      Metaplasia, Osseous                                           1 (2%)                                                          
      Mineralization                                                1 (2%)                                                          
      Nephropathy                                     34 (68%)     38 (76%)     40 (80%)     36 (72%)                               
      Pigmentation, Bile                               1 (2%)                                                                       
      Cortex, Cyst                                     1 (2%)       8 (16%)      5 (10%)      4 (8%)                                
      Papilla, Inflammation                            3 (6%)       4 (8%)       3 (6%)       2 (4%)                                
      Papilla, Necrosis                                                          1 (2%)                                             
      Pelvis, Dilatation                               1 (2%)       2 (4%)       1 (2%)       3 (6%)                                
      Renal Tubule, Vacuolization Cytoplasmic                                    1 (2%)                                             
   Ureter                                                                       (2)          (1)                                    
      Degeneration                                                               1 (50%)      1 (100%)                              
      Inflammation                                                               1 (50%)                                            
   Urinary Bladder                                    (48)         (50)         (49)         (49)                                   
      Calculus Micro Observation Only                  1 (2%)       1 (2%)       2 (4%)       2 (4%)                                
      Infiltration Cellular                                                      1 (2%)       1 (2%)                                
      Inflammation                                     7 (15%)     12 (24%)      6 (12%)      8 (16%)                               
      Ulcer                                                         1 (2%)                                                          
      Muscularis, Inflammation                                                   1 (2%)                                             
      Muscularis, Necrosis                                                       1 (2%)                                             
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   13                                                              
NTP Experiment-Test: 05210-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            ETHYLBENZENE                                       Date: 04/23/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 08:53:41  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE MALE                          CONTROL      75 PPM       250          750                                       
                                                                             PPM          PPM                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
URINARY SYSTEM - CONT                                                                                                               
      Serosa, Fibrosis                                                           1 (2%)                                             
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   14                                                              
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                             ----------              END OF REPORT             ----------                                           
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