National Toxicology Program

National Toxicology Program
https://ntp.niehs.nih.gov/go/3728

TDMS Study 05123-06 Pathology Tables


                                     INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)
                                                            NICKEL OXIDE


NTP Experiment-Test: 05123-06                                                                                     Report: PEIRPT03
Study Type: CHRONIC                                                                                               Date: 05/20/95
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 05:20:49




       Facility:  Lovelace Inhalation Toxicology Research Institute

       Chemical CAS #:  1313-99-1

       Lock Date:  04/19/94

       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: 05123-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            NICKEL OXIDE                                       Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 05:20:49  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE FEMALE                        0 MG/M3      0 MG/M3      1.25MGM3     1.25MGM3     2.5MG/M3     2.5MG/M3        
                                                                  LUNGTX                    LUNGTX                    LUNGTX        
____________________________________________________________________________________________________________________________________
DISPOSITION SUMMARY                                                                                                                 
  Animals Initially In Study                          60           20           60           20           60           20           
  Scheduled Sacrifice                                              10                        10                        10           
  Early Deaths                                                                                                                      
    Moribund Sacrifice                                12            3           15            3            6            3           
    Natural Death                                      6            1            5            3           10            1           
    Accidently Killed                                  1                                                   1                        
  Survivors                                                                                                                         
    Moribund Sacrifice                                                           2                                                  
    Terminal Sacrifice                                40                        38                        42                        
    Natural Death                                      1                                                                            
    Terminal Sacrifice                                              6                         4                         6           
  Other                                                                                                    1                        
  Animals Examined Microscopically                    60           14           60           16           59           14           
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Gallbladder                                        (57)         (8)          (56)         (8)          (54)         (8)          
      Inflammation, Suppurative                                                                            1 (2%)                   
   Intestine Large, Cecum                             (57)         (8)          (57)         (8)          (54)         (8)          
      Hyperplasia, Lymphoid                            1 (2%)                                              4 (7%)                   
   Intestine Small, Duodenum                          (57)         (8)          (56)         (9)          (53)         (8)          
      Hyperplasia, Lymphoid                                                                                2 (4%)                   
      Inflammation, Suppurative                                                  1 (2%)                                             
   Intestine Small, Ileum                             (55)         (8)          (54)         (8)          (53)         (8)          
      Hyperplasia, Lymphoid                                                                                2 (4%)                   
   Liver                                              (60)         (9)          (60)         (11)         (59)         (9)          
      Abscess                                          1 (2%)                                                                       
      Basophilic Focus                                 1 (2%)                    1 (2%)                    1 (2%)                   
      Clear Cell Focus                                 2 (3%)                                              1 (2%)                   
      Eosinophilic Focus                               2 (3%)                                              2 (3%)                   
      Infiltration Cellular, Lymphocyte                                                                                 1 (11%)     
      Inflammation, Chronic                            1 (2%)                                 1 (9%)                                
      Inflammation, Chronic, Focal                     1 (2%)                    3 (5%)                    3 (5%)                   
      Mixed Cell Focus                                                                                     1 (2%)                   
      Hepatocyte, Fatty Change                                                                             1 (2%)                   
      Hepatocyte, Hyperplasia                                                    1 (2%)                                             
      Hepatocyte, Necrosis                                                       1 (2%)                    1 (2%)                   
      Hepatocyte, Vacuolization Cytoplasmic            1 (2%)                    1 (2%)                                             
      Sinusoid, Amyloid Deposition                                               1 (2%)                                             
   Mesentery                                          (2)                       (2)                       (1)                       
      Artery, Inflammation, Chronic                                              2 (100%)                                           
   Pancreas                                           (60)         (9)          (60)         (11)         (58)         (9)          
      Atrophy                                                                                              1 (2%)                   
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    2                                                              
NTP Experiment-Test: 05123-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            NICKEL OXIDE                                       Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 05:20:49  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE FEMALE                        0 MG/M3      0 MG/M3      1.25MGM3     1.25MGM3     2.5MG/M3     2.5MG/M3        
                                                                  LUNGTX                    LUNGTX                    LUNGTX        
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ALIMENTARY SYSTEM - CONT                                                                                                            
      Congestion                                                                                           1 (2%)                   
      Cyst                                                                                                 1 (2%)                   
      Infiltration Cellular, Lymphocyte                                                                    1 (2%)                   
      Inflammation, Chronic                                                      1 (2%)                                             
      Inflammation, Suppurative                                                                            1 (2%)                   
   Stomach, Forestomach                               (60)         (9)          (59)         (9)          (58)         (9)          
      Hyperkeratosis                                   1 (2%)                    8 (14%)                   2 (3%)                   
      Inflammation, Chronic                            1 (2%)                                                                       
      Inflammation, Suppurative                                                  1 (2%)                                             
   Stomach, Glandular                                 (59)         (9)          (59)         (9)          (58)         (9)          
      Inflammation, Chronic                            1 (2%)                                                                       
      Inflammation, Suppurative                                                  1 (2%)                                             
   Tooth                                              (2)                       (1)                       (1)                       
      Developmental Malformation                       1 (50%)                   1 (100%)                                           
      Inflammation                                     1 (50%)                                             1 (100%)                 
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Heart                                              (60)         (9)          (60)         (11)         (59)         (9)          
      Inflammation, Chronic Active                                                                         1 (2%)                   
      Inflammation, Suppurative                                                                            1 (2%)                   
      Arteriole, Inflammation, Chronic                 1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Cortex                                     (60)         (9)          (60)         (11)         (59)         (9)          
      Hyperplasia                                      1 (2%)                    2 (3%)                    1 (2%)                   
      Infiltration Cellular                                         1 (11%)                                                         
      Vacuolization Cytoplasmic                        1 (2%)                                                                       
      Spindle Cell, Hyperplasia                        4 (7%)                    1 (2%)       1 (9%)                                
   Adrenal Medulla                                    (60)         (7)          (59)         (11)         (59)         (9)          
      Degeneration                                     1 (2%)                                                                       
      Hyperplasia                                      1 (2%)                                                                       
      Spindle Cell, Hyperplasia                        1 (2%)                    2 (3%)                                             
   Islets, Pancreatic                                 (59)         (9)          (59)         (11)         (58)         (9)          
      Hyperplasia                                                                1 (2%)                                             
   Pituitary Gland                                    (59)         (9)          (60)         (11)         (57)         (9)          
      Pars Distalis, Angiectasis                       7 (12%)                  10 (17%)                  11 (19%)      1 (11%)     
      Pars Distalis, Hyperplasia                      10 (17%)                   9 (15%)                   4 (7%)                   
   Thyroid Gland                                      (59)         (8)          (60)         (11)         (59)         (9)          
      Hyperplasia, Cystic                             26 (44%)                  25 (42%)      1 (9%)      32 (54%)                  
      Infiltration Cellular, Lymphocyte                1 (2%)                                                                       
      Inflammation, Suppurative                                                  2 (3%)                                             
____________________________________________________________________________________________________________________________________
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    3                                                              
NTP Experiment-Test: 05123-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            NICKEL OXIDE                                       Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 05:20:49  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE FEMALE                        0 MG/M3      0 MG/M3      1.25MGM3     1.25MGM3     2.5MG/M3     2.5MG/M3        
                                                                  LUNGTX                    LUNGTX                    LUNGTX        
____________________________________________________________________________________________________________________________________
                                                                                                                                    
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Clitoral Gland                                     (54)         (8)          (56)         (11)         (53)         (9)          
      Ectasia                                          1 (2%)                    2 (4%)                                             
      Inflammation, Chronic                            2 (4%)                                                                       
      Pigmentation                                     5 (9%)                    4 (7%)                    5 (9%)                   
   Ovary                                              (57)         (9)          (60)         (11)         (57)         (8)          
      Abscess                                          2 (4%)                                                                       
      Congestion                                                                 1 (2%)                                             
      Cyst                                             8 (14%)                  14 (23%)      1 (9%)       9 (16%)                  
      Inflammation, Suppurative                        1 (2%)                                              1 (2%)                   
      Rete Ovarii, Thrombosis                          1 (2%)                                                                       
   Uterus                                             (60)         (9)          (60)         (11)         (58)         (9)          
      Cyst                                                                                                 1 (2%)                   
      Dilatation                                                                              1 (9%)                                
      Inflammation, Suppurative                        1 (2%)                                                                       
      Bilateral, Dilatation                                                      1 (2%)                                             
      Bilateral, Endometrium, Hyperplasia                           1 (11%)                                                         
      Endometrium, Hyperplasia                                      3 (33%)                   5 (45%)                   5 (56%)     
      Endometrium, Hyperplasia, Cystic                24 (40%)                  33 (55%)      1 (9%)      28 (48%)      2 (22%)     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Bone Marrow                                        (60)         (9)          (59)         (11)         (58)         (9)          
      Myelofibrosis                                    3 (5%)                    2 (3%)                                             
      Necrosis                                                                   1 (2%)                    1 (2%)                   
      Myeloid Cell, Hyperplasia                        5 (8%)                    3 (5%)       1 (9%)       3 (5%)                   
   Lymph Node                                         (15)                      (8)          (1)          (9)          (1)          
      Iliac, Hyperplasia, Lymphoid                     3 (20%)                   2 (25%)                   1 (11%)                  
      Iliac, Pigmentation                                                        1 (13%)                                            
      Pancreatic, Hyperplasia, Lymphoid                                                                                 1 (100%)    
      Renal, Hyperplasia, Lymphoid                     4 (27%)                   1 (13%)                   1 (11%)                  
   Lymph Node, Bronchial                              (53)         (9)          (58)         (14)         (56)         (13)         
      Congestion                                                                 2 (3%)                    1 (2%)                   
      Hyperplasia                                                                             1 (7%)                                
      Hyperplasia, Lymphoid                           14 (26%)                  36 (62%)      4 (29%)     38 (68%)      6 (46%)     
      Pigmentation                                                              54 (93%)      9 (64%)     53 (95%)     13 (100%)    
   Lymph Node, Mandibular                             (58)         (8)          (58)         (11)         (55)         (9)          
      Congestion                                                                 1 (2%)                                 1 (11%)     
      Hyperplasia, Lymphoid                           16 (28%)                  15 (26%)      6 (55%)     16 (29%)      2 (22%)     
      Hyperplasia, Macrophage                                                    1 (2%)                                             
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    4                                                              
NTP Experiment-Test: 05123-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            NICKEL OXIDE                                       Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 05:20:49  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE FEMALE                        0 MG/M3      0 MG/M3      1.25MGM3     1.25MGM3     2.5MG/M3     2.5MG/M3        
                                                                  LUNGTX                    LUNGTX                    LUNGTX        
____________________________________________________________________________________________________________________________________
                                                                                                                                    
HEMATOPOIETIC SYSTEM - CONT                                                                                                         
      Inflammation, Suppurative                                                                            1 (2%)                   
   Lymph Node, Mesenteric                             (53)         (6)          (58)         (10)         (51)         (8)          
      Congestion                                                                 4 (7%)                                 1 (13%)     
      Ectasia                                                                    1 (2%)                                             
      Hyperplasia, Lymphoid                            8 (15%)                   3 (5%)                    8 (16%)                  
      Inflammation                                                                                         1 (2%)                   
      Inflammation, Chronic Active                                                                         1 (2%)                   
      Inflammation, Suppurative                        1 (2%)                                                                       
   Lymph Node, Mediastinal                            (35)         (2)          (27)         (7)          (31)         (5)          
      Hyperplasia                                                                             1 (14%)                               
      Hyperplasia, Lymphoid                            1 (3%)                    3 (11%)      1 (14%)      3 (10%)                  
      Pigmentation                                                               2 (7%)                    1 (3%)                   
   Spleen                                             (60)         (9)          (60)         (12)         (59)         (9)          
      Hematopoietic Cell Proliferation                 8 (13%)                   4 (7%)       2 (17%)      7 (12%)      1 (11%)     
      Hyperplasia, Lymphoid                           12 (20%)      1 (11%)     16 (27%)      4 (33%)     21 (36%)      2 (22%)     
      Hyperplasia, Macrophage                                                    1 (2%)                                             
   Thymus                                             (56)         (8)          (55)         (11)         (57)         (8)          
      Atrophy                                          1 (2%)                                              1 (2%)                   
      Hyperplasia, Lymphoid                            1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Mammary Gland                                      (59)         (9)          (60)         (11)         (59)         (9)          
      Hyperplasia, Glandular                           6 (10%)                   3 (5%)       1 (9%)       8 (14%)                  
   Skin                                               (4)                       (6)          (2)          (5)          (1)          
      Alopecia                                                                   1 (17%)                   1 (20%)                  
      Inflammation, Chronic Active                     1 (25%)                                                                      
      Inflammation, Suppurative                                                                                         1 (100%)    
      Pinna, Cyst Epithelial Inclusion                                           1 (17%)                                            
      Subcutaneous Tissue, Edema                       1 (25%)                   1 (17%)                                            
      Subcutaneous Tissue, Inflammation,                                                                                            
          Suppurative                                                                                      1 (20%)                  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   Bone                                               (60)         (9)          (59)         (11)         (59)         (9)          
      Fracture                                         1 (2%)                                                                       
      Hyperostosis                                    17 (28%)                  25 (42%)                  25 (42%)      1 (11%)     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    5                                                              
NTP Experiment-Test: 05123-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            NICKEL OXIDE                                       Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 05:20:49  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE FEMALE                        0 MG/M3      0 MG/M3      1.25MGM3     1.25MGM3     2.5MG/M3     2.5MG/M3        
                                                                  LUNGTX                    LUNGTX                    LUNGTX        
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (60)         (9)          (60)         (11)         (59)         (9)          
      Hypothalamus, Compression                                                  2 (3%)                    6 (10%)                  
      Pons, Compression                                                          1 (2%)                                             
   Spinal Cord                                                                  (1)                                                 
      Hemorrhage                                                                 1 (100%)                                           
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Larynx                                             (58)         (9)          (57)         (11)         (58)         (9)          
      Inflammation, Suppurative                                                  1 (2%)                    1 (2%)                   
   Lung                                               (60)         (14)         (60)         (16)         (59)         (14)         
      Fibrosis                                                                                             1 (2%)                   
      Hemorrhage                                                                 2 (3%)                                             
      Inflammation, Chronic                            7 (12%)                  40 (67%)      6 (38%)     50 (85%)     11 (79%)     
      Inflammation, Chronic Active                                                                         1 (2%)                   
      Pigmentation, Hemosiderin                        2 (3%)                                                                       
      Alveolar Epithelium, Hyperplasia                                          34 (57%)      1 (6%)      37 (63%)      5 (36%)     
      Alveolar Epithelium, Hyperplasia, Focal                                                              1 (2%)                   
      Alveolus, Hemorrhage                                                                                 1 (2%)                   
      Alveolus, Hyperplasia, Macrophage                1 (2%)                    1 (2%)       1 (6%)                                
      Alveolus, Pigmentation                                                    59 (98%)     13 (81%)     58 (98%)     13 (93%)     
      Alveolus, Proteinosis                                                      8 (13%)                  17 (29%)                  
   Nose                                               (59)         (13)         (60)         (15)         (59)         (13)         
      Inflammation, Suppurative                                                  1 (2%)                                             
      Capillary, Thrombosis                            1 (2%)                                                                       
      Olfactory Epithelium, Degeneration              15 (25%)      4 (31%)      9 (15%)      1 (7%)       2 (3%)                   
      Respiratory Epithelium, Degeneration            19 (32%)      2 (15%)     14 (23%)      2 (13%)     10 (17%)      3 (23%)     
      Respiratory Epithelium, Hyperplasia              1 (2%)                    1 (2%)                                             
      Respiratory Epithelium, Inflammation, Chronic                              1 (2%)                                             
      Respiratory Epithelium, Inflammation,                                                                                         
          Suppurative                                 17 (29%)                  16 (27%)      2 (13%)     17 (29%)      1 (8%)      
      Respiratory Epithelium, Metaplasia, Squamous    10 (17%)                   9 (15%)                  13 (22%)      1 (8%)      
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   Ear                                                (2)                       (1)                       (1)                       
      External Ear, Hyperkeratosis                                               1 (100%)                                           
____________________________________________________________________________________________________________________________________
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    6                                                              
NTP Experiment-Test: 05123-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            NICKEL OXIDE                                       Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 05:20:49  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE FEMALE                        0 MG/M3      0 MG/M3      1.25MGM3     1.25MGM3     2.5MG/M3     2.5MG/M3        
                                                                  LUNGTX                    LUNGTX                    LUNGTX        
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (60)         (14)         (60)         (16)         (59)         (14)         
      Hydronephrosis                                   1 (2%)                                                                       
      Infiltration Cellular, Lymphocyte                             1 (7%)                    2 (13%)      2 (3%)       1 (7%)      
      Inflammation, Chronic                                                      1 (2%)                    1 (2%)       1 (7%)      
      Metaplasia, Osseous                              1 (2%)                                                                       
      Nephropathy                                      2 (3%)                    3 (5%)                    3 (5%)                   
      Glomerulus, Thrombosis                           1 (2%)                                                                       
      Medulla, Cyst                                                                                        1 (2%)                   
      Pelvis, Infiltration Cellular, Lymphocyte                                  1 (2%)                                             
      Renal Tubule, Hyperplasia                        1 (2%)                                                                       
   Urinary Bladder                                    (60)         (8)          (58)         (9)          (56)         (9)          
      Inflammation, Suppurative                                                                            1 (2%)                   
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    7                                                              
NTP Experiment-Test: 05123-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            NICKEL OXIDE                                       Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 05:20:49  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE FEMALE                        5.0MG/M3     5.0MG/M3                                                            
                                                                  LUNGTX                                                            
____________________________________________________________________________________________________________________________________
DISPOSITION SUMMARY                                                                                                                 
  Animals Initially In Study                          60           20                                                               
  Scheduled Sacrifice                                              10                                                               
  Early Deaths                                                                                                                      
    Moribund Sacrifice                                12            4                                                               
    Natural Death                                      9            1                                                               
  Survivors                                                                                                                         
    Terminal Sacrifice                                38                                                                            
    Terminal Sacrifice                                              5                                                               
  Other                                                1                                                                            
  Animals Examined Microscopically                    59           15                                                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Intestine Large, Cecum                             (52)         (9)                                                              
      Hyperplasia, Lymphoid                            1 (2%)                                                                       
   Liver                                              (58)         (10)                                                             
      Basophilic Focus                                 1 (2%)                                                                       
      Clear Cell Focus                                 1 (2%)                                                                       
      Hepatocyte, Necrosis                             3 (5%)                                                                       
   Mesentery                                          (2)          (1)                                                              
      Inflammation, Chronic Active                                  1 (100%)                                                        
      Fat, Necrosis                                                 1 (100%)                                                        
   Stomach, Forestomach                               (55)         (10)                                                             
      Hyperkeratosis                                   1 (2%)                                                                       
      Hyperplasia, Squamous                            1 (2%)                                                                       
   Tooth                                              (2)                                                                           
      Developmental Malformation                       1 (50%)                                                                      
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Heart                                              (59)         (10)                                                             
      Venule, Inflammation, Chronic Active                          1 (10%)                                                         
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Cortex                                     (57)         (10)                                                             
      Hyperplasia                                      1 (2%)                                                                       
      Spindle Cell, Hyperplasia                        1 (2%)                                                                       
   Pituitary Gland                                    (57)         (10)                                                             
      Pars Distalis, Angiectasis                       7 (12%)                                                                      
      Pars Distalis, Hyperplasia                       8 (14%)      1 (10%)                                                         
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    8                                                              
NTP Experiment-Test: 05123-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            NICKEL OXIDE                                       Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 05:20:49  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE FEMALE                        5.0MG/M3     5.0MG/M3                                                            
                                                                  LUNGTX                                                            
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ENDOCRINE SYSTEM - CONT                                                                                                             
      Pars Distalis, Necrosis                          1 (2%)                                                                       
   Thyroid Gland                                      (59)         (10)                                                             
      Hyperplasia, Cystic                             25 (42%)      1 (10%)                                                         
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Clitoral Gland                                     (50)         (10)                                                             
      Ectasia                                          3 (6%)                                                                       
      Inflammation, Chronic                                         1 (10%)                                                         
      Inflammation, Chronic Active                     1 (2%)                                                                       
      Pigmentation                                    12 (24%)                                                                      
   Ovary                                              (58)         (10)                                                             
      Angiectasis                                      2 (3%)                                                                       
      Cyst                                             7 (12%)                                                                      
   Uterus                                             (58)         (11)                                                             
      Inflammation, Suppurative                        1 (2%)       1 (9%)                                                          
      Endometrium, Hyperplasia                                      5 (45%)                                                         
      Endometrium, Hyperplasia, Cystic                26 (45%)      3 (27%)                                                         
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Bone Marrow                                        (58)         (10)                                                             
      Myelofibrosis                                    2 (3%)                                                                       
      Myeloid Cell, Hyperplasia                                     1 (10%)                                                         
   Lymph Node                                         (9)                                                                           
      Iliac, Hyperplasia, Lymphoid                     1 (11%)                                                                      
      Iliac, Hyperplasia, Macrophage                   1 (11%)                                                                      
      Pancreatic, Hyperplasia, Lymphoid                1 (11%)                                                                      
      Renal, Hyperplasia, Lymphoid                     2 (22%)                                                                      
      Renal, Inflammation, Chronic Active              1 (11%)                                                                      
   Lymph Node, Bronchial                              (57)         (15)                                                             
      Congestion                                       2 (4%)                                                                       
      Hyperplasia, Lymphoid                           41 (72%)      7 (47%)                                                         
      Pigmentation                                    55 (96%)     15 (100%)                                                        
   Lymph Node, Mandibular                             (54)         (9)                                                              
      Hyperplasia, Lymphoid                           13 (24%)      1 (11%)                                                         
   Lymph Node, Mesenteric                             (51)         (9)                                                              
      Congestion                                       1 (2%)                                                                       
      Hematopoietic Cell Proliferation                 1 (2%)                                                                       
      Hyperplasia, Lymphoid                           13 (25%)                                                                      
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    9                                                              
NTP Experiment-Test: 05123-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            NICKEL OXIDE                                       Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 05:20:49  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE FEMALE                        5.0MG/M3     5.0MG/M3                                                            
                                                                  LUNGTX                                                            
____________________________________________________________________________________________________________________________________
                                                                                                                                    
HEMATOPOIETIC SYSTEM - CONT                                                                                                         
   Lymph Node, Mediastinal                            (24)         (9)                                                              
      Hyperplasia, Lymphoid                            2 (8%)                                                                       
      Pigmentation                                     4 (17%)      1 (11%)                                                         
   Spleen                                             (58)         (10)                                                             
      Congestion                                       2 (3%)                                                                       
      Hematopoietic Cell Proliferation                 5 (9%)                                                                       
      Hyperplasia, Lymphoid                           17 (29%)                                                                      
      Hyperplasia, Macrophage                          1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Mammary Gland                                      (58)         (10)                                                             
      Hyperplasia, Glandular                           8 (14%)                                                                      
   Skin                                               (11)         (2)                                                              
      Alopecia                                         1 (9%)                                                                       
      Edema                                            1 (9%)                                                                       
      Hemorrhage                                       2 (18%)                                                                      
      Inflammation, Chronic                            1 (9%)                                                                       
      Epidermis, Inflammation, Suppurative                          1 (50%)                                                         
      Subcutaneous Tissue, Inflammation, Chronic                                                                                    
          Active                                                    1 (50%)                                                         
      Subcutaneous Tissue, Necrosis                                 1 (50%)                                                         
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   Bone                                               (58)         (10)                                                             
      Hyperostosis                                    23 (40%)      1 (10%)                                                         
      Pelvis, Fracture                                 1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (59)         (10)                                                             
      Hypothalamus, Compression                        4 (7%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Lung                                               (59)         (15)                                                             
      Fibrosis                                         3 (5%)                                                                       
      Inflammation, Chronic                           48 (81%)     12 (80%)                                                         
      Metaplasia, Squamous                             1 (2%)                                                                       
      Alveolar Epithelium, Hyperplasia                37 (63%)      6 (40%)                                                         
      Alveolus, Pigmentation                          59 (100%)    15 (100%)                                                        
      Alveolus, Proteinosis                           27 (46%)      5 (33%)                                                         
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   10                                                              
NTP Experiment-Test: 05123-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            NICKEL OXIDE                                       Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 05:20:49  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE FEMALE                        5.0MG/M3     5.0MG/M3                                                            
                                                                  LUNGTX                                                            
____________________________________________________________________________________________________________________________________
                                                                                                                                    
RESPIRATORY SYSTEM - CONT                                                                                                           
   Nose                                               (57)         (15)                                                             
      Olfactory Epithelium, Degeneration               6 (11%)      1 (7%)                                                          
      Respiratory Epithelium, Degeneration            16 (28%)      4 (27%)                                                         
      Respiratory Epithelium, Inflammation,                                                                                         
          Suppurative                                 21 (37%)                                                                      
      Respiratory Epithelium, Metaplasia, Squamous    15 (26%)                                                                      
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   Ear                                                (1)          (1)                                                              
      External Ear, Hemorrhage                                      1 (100%)                                                        
   Eye                                                (2)                                                                           
      Cornea, Inflammation                             2 (100%)                                                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (58)         (15)                                                             
      Infiltration Cellular, Lymphocyte                             2 (13%)                                                         
      Necrosis                                         1 (2%)                                                                       
      Nephropathy                                      1 (2%)       1 (7%)                                                          
      Cortex, Cyst                                     1 (2%)                                                                       
   Urethra                                                         (1)                                                              
      Concretion                                                    1 (100%)                                                        
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   11                                                              
NTP Experiment-Test: 05123-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            NICKEL OXIDE                                       Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 05:20:49  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE MALE                          0 MG/M3      O MG/M3      1.25MGM3     1.25MGM3     2.5MG/M3     2.5MG/M3        
                                                                  LUNGTX                    LUNGTX                    LUNGTX        
____________________________________________________________________________________________________________________________________
DISPOSITION SUMMARY                                                                                                                 
  Animals Initially In Study                          60           20           60           20           60           20           
  Scheduled Sacrifice                                              10                        10                        10           
  Early Deaths                                                                                                                      
    Moribund Sacrifice                                22            1           20            6           23            3           
    Natural Death                                     14            1           17            1            8            3           
    Accidently Killed                                  4            6                                                               
  Survivors                                                                                                                         
    Terminal Sacrifice                                19                        23                        29                        
    Terminal Sacrifice                                              2                         3                         4           
  Other                                                1                                                                            
  Animals Examined Microscopically                    55           12           60           17           60           16           
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Gallbladder                                        (45)         (7)          (49)         (10)         (53)         (9)          
      Necrosis                                                                                             1 (2%)                   
   Intestine Large, Cecum                             (47)         (7)          (49)         (12)         (56)         (9)          
      Inflammation, Chronic                                                                                1 (2%)                   
   Intestine Small, Ileum                             (49)         (7)          (43)         (11)         (52)         (8)          
      Inflammation, Suppurative                        1 (2%)                                                                       
      Ulcer                                            1 (2%)                                                                       
   Liver                                              (55)         (8)          (60)         (12)         (60)         (13)         
      Angiectasis                                                                1 (2%)                                             
      Basophilic Focus                                 1 (2%)                    2 (3%)       1 (8%)       2 (3%)       1 (8%)      
      Clear Cell Focus                                                                                     1 (2%)                   
      Congestion                                                                                           1 (2%)                   
      Cyst                                             1 (2%)                                              1 (2%)                   
      Eosinophilic Focus                                                         1 (2%)                                             
      Hepatodiaphragmatic Nodule                                                 1 (2%)                                             
      Hyperplasia, Macrophage                          1 (2%)                                                                       
      Infarct                                                                    5 (8%)       1 (8%)       1 (2%)                   
      Inflammation, Suppurative                                                                                         1 (8%)      
      Mixed Cell Focus                                                           1 (2%)                    1 (2%)                   
      Thrombosis                                                                 3 (5%)                    1 (2%)                   
      Bile Duct, Cyst                                                                                      1 (2%)                   
      Hepatocyte, Cytomegaly                           1 (2%)                                              1 (2%)                   
      Hepatocyte, Cytoplasmic Alteration               1 (2%)                                                                       
      Hepatocyte, Hyperplasia                                                    1 (2%)                                             
      Hepatocyte, Necrosis                             4 (7%)       1 (13%)      1 (2%)       1 (8%)       4 (7%)                   
   Mesentery                                          (1)                       (1)                                                 
      Hemorrhage                                                                 1 (100%)                                           
      Thrombosis                                                                 1 (100%)                                           
      Vein, Inflammation, Chronic                                                1 (100%)                                           
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   12                                                              
NTP Experiment-Test: 05123-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            NICKEL OXIDE                                       Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 05:20:49  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE MALE                          0 MG/M3      O MG/M3      1.25MGM3     1.25MGM3     2.5MG/M3     2.5MG/M3        
                                                                  LUNGTX                    LUNGTX                    LUNGTX        
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ALIMENTARY SYSTEM - CONT                                                                                                            
   Pancreas                                           (52)         (7)          (58)         (12)         (60)         (11)         
      Inflammation, Chronic                            1 (2%)                                                                       
      Inflammation, Chronic Active                                               1 (2%)                                             
   Salivary Glands                                    (55)         (7)          (60)         (12)         (60)         (11)         
      Infiltration Cellular, Lymphocyte                             1 (14%)                                                         
   Stomach, Forestomach                               (52)         (7)          (57)         (11)         (60)         (10)         
      Hyperkeratosis                                                             1 (2%)                    1 (2%)                   
   Stomach, Glandular                                 (53)         (7)          (57)         (11)         (60)         (10)         
      Inflammation, Chronic                                                      1 (2%)                                             
      Inflammation, Suppurative                                                  1 (2%)                    1 (2%)       1 (10%)     
   Tooth                                              (2)                       (5)                       (4)                       
      Dysplasia                                        2 (100%)                  4 (80%)                   1 (25%)                  
      Peridontal Tissue, Inflammation, Chronic                                                                                      
          Active                                                                                           1 (25%)                  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Heart                                              (55)         (7)          (60)         (12)         (60)         (11)         
      Atrium, Thrombosis                                                         1 (2%)                                             
      Ventricle, Thrombosis                                                                                1 (2%)                   
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Cortex                                     (55)         (7)          (60)         (12)         (59)         (11)         
      Cyst                                                                                                              1 (9%)      
      Hyperplasia                                      6 (11%)                   4 (7%)       1 (8%)       6 (10%)                  
      Bilateral, Hyperplasia                                                     1 (2%)                                             
      Bilateral, Spindle Cell, Hyperplasia                                                                 1 (2%)                   
      Spindle Cell, Hyperplasia                        1 (2%)                    2 (3%)                    1 (2%)                   
   Islets, Pancreatic                                 (52)         (7)          (57)         (12)         (60)         (11)         
      Hyperplasia                                      2 (4%)                                              2 (3%)                   
   Parathyroid Gland                                  (36)         (6)          (42)         (9)          (49)         (8)          
      Cyst                                             1 (3%)                    1 (2%)                                             
      Hyperplasia, Cystic                                                        2 (5%)                                             
   Pituitary Gland                                    (54)         (7)          (55)         (12)         (57)         (11)         
      Pars Distalis, Cyst                                                        1 (2%)                    1 (2%)                   
      Pars Distalis, Hyperplasia                       2 (4%)                    1 (2%)                                             
   Thyroid Gland                                      (53)         (7)          (60)         (12)         (60)         (11)         
      Hyperplasia, Cystic                             13 (25%)                  24 (40%)      3 (25%)     25 (42%)                  
      Inflammation, Chronic                                                      1 (2%)                                             
      Inflammation, Suppurative                                                                                         1 (9%)      
____________________________________________________________________________________________________________________________________
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   13                                                              
NTP Experiment-Test: 05123-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            NICKEL OXIDE                                       Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 05:20:49  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE MALE                          0 MG/M3      O MG/M3      1.25MGM3     1.25MGM3     2.5MG/M3     2.5MG/M3        
                                                                  LUNGTX                    LUNGTX                    LUNGTX        
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   Tissue NOS                                         (1)          (1)                       (1)          (3)                       
      Abscess                                          1 (100%)                                                                     
      Inflammation, Suppurative                                                                            1 (33%)                  
      Necrosis, Chronic                                                                                    1 (33%)                  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Epididymis                                         (54)         (7)          (60)         (12)         (60)         (11)         
      Granuloma Sperm                                                            1 (2%)                    1 (2%)                   
      Inflammation, Chronic                            2 (4%)                                                                       
   Penis                                              (7)          (1)          (8)          (3)          (6)          (1)          
      Concretion                                       1 (14%)                   3 (38%)      2 (67%)      4 (67%)      1 (100%)    
      Hemorrhage                                                                 1 (13%)                   1 (17%)                  
      Inflammation                                                               1 (13%)                                            
      Inflammation, Chronic                            1 (14%)                                                                      
      Inflammation, Suppurative                        5 (71%)      1 (100%)     1 (13%)                   1 (17%)                  
      Mineralization                                                             1 (13%)                                            
      Necrosis, Chronic                                                          1 (13%)                   1 (17%)                  
   Preputial Gland                                    (55)         (7)          (59)         (15)         (60)         (12)         
      Atrophy                                                                                 1 (7%)       4 (7%)                   
      Concretion                                                                 1 (2%)                                             
      Ectasia                                         15 (27%)      5 (71%)     16 (27%)      6 (40%)     22 (37%)      6 (50%)     
      Hemorrhage                                                                 1 (2%)                                             
      Inflammation, Chronic                            2 (4%)                    7 (12%)                   5 (8%)                   
      Inflammation, Chronic Active                     9 (16%)                  10 (17%)      2 (13%)      6 (10%)      1 (8%)      
      Inflammation, Suppurative                       14 (25%)      1 (14%)      6 (10%)      3 (20%)     12 (20%)      1 (8%)      
      Bilateral, Ectasia                              22 (40%)      1 (14%)     30 (51%)      4 (27%)     34 (57%)      3 (25%)     
      Bilateral, Inflammation, Chronic Active                                    2 (3%)                    1 (2%)                   
      Bilateral, Inflammation, Suppurative                                                                              1 (8%)      
      Duct, Concretion                                                                                                  1 (8%)      
      Duct, Ectasia                                                                           3 (20%)                               
   Prostate                                           (51)         (7)          (55)         (11)         (57)         (11)         
      Inflammation, Chronic Active                                               1 (2%)                                             
      Inflammation, Suppurative                        1 (2%)                    2 (4%)                    1 (2%)                   
      Epithelium, Hyperplasia                                                    1 (2%)                                             
   Seminal Vesicle                                    (53)         (7)          (59)         (12)         (60)         (11)         
      Dilatation                                       1 (2%)                    6 (10%)      2 (17%)      9 (15%)      2 (18%)     
      Inflammation, Chronic                                                                                1 (2%)                   
   Testes                                             (55)         (7)          (59)         (12)         (60)         (11)         
      Atrophy                                                                    2 (3%)       1 (8%)       1 (2%)                   
      Congestion                                                                              1 (8%)                                
      Cyst                                                                       1 (2%)                                             
      Inflammation, Suppurative                        1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   14                                                              
NTP Experiment-Test: 05123-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            NICKEL OXIDE                                       Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 05:20:49  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE MALE                          0 MG/M3      O MG/M3      1.25MGM3     1.25MGM3     2.5MG/M3     2.5MG/M3        
                                                                  LUNGTX                    LUNGTX                    LUNGTX        
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Bone Marrow                                        (54)         (7)          (59)         (12)         (60)         (11)         
      Myeloid Cell, Hyperplasia                        5 (9%)                    9 (15%)      4 (33%)     13 (22%)      2 (18%)     
   Lymph Node                                         (21)         (2)          (13)         (6)          (17)         (3)          
      Iliac, Hyperplasia, Histiocytic                  1 (5%)                                                                       
      Iliac, Hyperplasia, Lymphoid                     8 (38%)                   5 (38%)      3 (50%)      9 (53%)      2 (67%)     
      Iliac, Inflammation, Suppurative                                           1 (8%)                                             
      Iliac, Pigmentation                                                        2 (15%)      2 (33%)      2 (12%)      1 (33%)     
      Inguinal, Hyperplasia                            1 (5%)                                                                       
      Inguinal, Hyperplasia, Lymphoid                 12 (57%)      1 (50%)      7 (54%)      2 (33%)      9 (53%)      2 (67%)     
      Inguinal, Pigmentation                           1 (5%)                    2 (15%)                                            
      Pancreatic, Hyperplasia, Lymphoid                                                                                 1 (33%)     
      Pancreatic, Inflammation, Granulomatous          1 (5%)                                              1 (6%)                   
      Renal, Hyperplasia, Histiocytic                  1 (5%)                                                                       
      Renal, Hyperplasia, Lymphoid                     1 (5%)       2 (100%)     2 (15%)                                1 (33%)     
      Renal, Pigmentation                                                        1 (8%)       1 (17%)                               
   Lymph Node, Bronchial                              (43)         (11)         (50)         (14)         (56)         (15)         
      Atrophy                                                                    1 (2%)                                             
      Congestion                                       1 (2%)                                              1 (2%)                   
      Edema                                                                      1 (2%)                                             
      Hyperplasia, Lymphoid                            5 (12%)                  16 (32%)      2 (14%)     28 (50%)      3 (20%)     
      Inflammation, Chronic Active                                                                                      1 (7%)      
      Inflammation, Granulomatous                      1 (2%)                                                                       
      Pigmentation                                                              49 (98%)     12 (86%)     56 (100%)    15 (100%)    
   Lymph Node, Mandibular                             (45)         (7)          (51)         (11)         (57)         (11)         
      Hyperplasia, Histiocytic                                                   1 (2%)                                             
      Hyperplasia, Lymphoid                            3 (7%)                    3 (6%)                    3 (5%)       1 (9%)      
   Lymph Node, Mesenteric                             (43)         (7)          (48)         (12)         (52)         (9)          
      Congestion                                       3 (7%)       1 (14%)     11 (23%)      2 (17%)     12 (23%)                  
      Hematopoietic Cell Proliferation                                           1 (2%)                                             
      Hyperplasia, Lymphoid                            3 (7%)                    2 (4%)       2 (17%)      3 (6%)       2 (22%)     
      Hyperplasia, Macrophage                                                                              1 (2%)                   
      Inflammation, Suppurative                        3 (7%)       1 (14%)      1 (2%)                    2 (4%)                   
      Pigmentation                                                               1 (2%)                                             
   Lymph Node, Mediastinal                            (16)         (8)          (19)         (2)          (19)         (8)          
      Hyperplasia, Lymphoid                            1 (6%)                                                                       
      Inflammation, Chronic                                                                                             1 (13%)     
      Pigmentation                                                               3 (16%)                   1 (5%)                   
   Spleen                                             (54)         (7)          (60)         (12)         (60)         (11)         
      Angiectasis                                                                1 (2%)                                             
      Hematopoietic Cell Proliferation                16 (30%)      1 (14%)     12 (20%)      2 (17%)     11 (18%)      2 (18%)     
      Hyperplasia, Lymphoid                            2 (4%)       2 (29%)      4 (7%)       1 (8%)       5 (8%)       2 (18%)     
   Thymus                                             (43)         (7)          (49)         (8)          (47)         (10)         
      Atrophy                                          1 (2%)                    1 (2%)                                             
      Cyst                                                                                                 1 (2%)                   
      Inflammation, Granulomatous                                                                                       1 (10%)     
      Pigmentation                                                               1 (2%)                                             
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   15                                                              
NTP Experiment-Test: 05123-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            NICKEL OXIDE                                       Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 05:20:49  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE MALE                          0 MG/M3      O MG/M3      1.25MGM3     1.25MGM3     2.5MG/M3     2.5MG/M3        
                                                                  LUNGTX                    LUNGTX                    LUNGTX        
____________________________________________________________________________________________________________________________________
                                                                                                                                    
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Skin                                               (16)                      (18)         (5)          (22)         (2)          
      Alopecia                                         1 (6%)                    1 (6%)                                             
      Inflammation, Chronic                                                      1 (6%)                                             
      Inflammation, Chronic Active                     1 (6%)                    2 (11%)                                            
      Inflammation, Suppurative                       13 (81%)                   8 (44%)      3 (60%)     14 (64%)      2 (100%)    
      Necrosis                                                                   1 (6%)       1 (20%)      1 (5%)                   
      Prepuce, Inflammation, Chronic Active                                                                1 (5%)                   
      Prepuce, Inflammation, Suppurative                                         4 (22%)      1 (20%)      3 (14%)                  
      Prepuce, Necrosis                                                                                    1 (5%)                   
      Subcutaneous Tissue, Edema                                                 1 (6%)       1 (20%)                               
      Subcutaneous Tissue, Fibrosis                                              1 (6%)                                             
      Subcutaneous Tissue, Hemorrhage                                            1 (6%)                                             
      Subcutaneous Tissue, Inflammation, Chronic                                                                                    
          Active                                                                                           1 (5%)                   
      Subcutaneous Tissue, Inflammation,                                                                                            
          Suppurative                                                                                      1 (5%)                   
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   Bone                                               (55)         (7)          (60)         (12)         (60)         (11)         
      Developmental Malformation                                                                           1 (2%)                   
      Fracture Healed                                  2 (4%)                                 1 (8%)                                
      Hemorrhage                                                                 1 (2%)                                             
      Hyperostosis                                     2 (4%)                                              3 (5%)       1 (9%)      
      Vertebra, Inflammation, Suppurative              1 (2%)                                                                       
   Skeletal Muscle                                    (1)                                                                           
      Inflammation, Suppurative                        1 (100%)                                                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (55)         (7)          (60)         (12)         (60)         (11)         
      Pons, Demyelination                                                        2 (3%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Lung                                               (55)         (12)         (60)         (17)         (60)         (16)         
      Hemorrhage                                                                 1 (2%)                    2 (3%)                   
      Hyperplasia, Macrophage                                                    1 (2%)                                             
      Inflammation, Chronic                                         1 (8%)      20 (33%)      3 (18%)     32 (53%)      7 (44%)     
      Thrombosis                                                                 2 (3%)                                             
      Alveolar Epithelium, Hyperplasia                                          23 (38%)      2 (12%)     37 (62%)      3 (19%)     
      Alveolar Epithelium, Hyperplasia, Focal          1 (2%)       1 (8%)       1 (2%)                    2 (3%)                   
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   16                                                              
NTP Experiment-Test: 05123-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            NICKEL OXIDE                                       Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 05:20:49  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE MALE                          0 MG/M3      O MG/M3      1.25MGM3     1.25MGM3     2.5MG/M3     2.5MG/M3        
                                                                  LUNGTX                    LUNGTX                    LUNGTX        
____________________________________________________________________________________________________________________________________
                                                                                                                                    
RESPIRATORY SYSTEM - CONT                                                                                                           
      Alveolus, Pigmentation                                                    58 (97%)     17 (100%)    60 (100%)    16 (100%)    
      Alveolus, Proteinosis                                                     11 (18%)      1 (6%)      19 (32%)      4 (25%)     
      Pleura, Fibrosis                                                                                                  1 (6%)      
   Nose                                               (53)         (12)         (59)         (17)         (60)         (16)         
      Inflammation, Suppurative                                                  2 (3%)                    1 (2%)                   
      Olfactory Epithelium, Degeneration                                         3 (5%)       1 (6%)       1 (2%)       1 (6%)      
      Olfactory Epithelium, Inflammation,                                                                                           
          Suppurative                                                            2 (3%)                                             
      Respiratory Epithelium, Degeneration             2 (4%)                    2 (3%)       1 (6%)       3 (5%)       1 (6%)      
      Respiratory Epithelium, Inflammation,                                                                                         
          Suppurative                                  6 (11%)                   7 (12%)      2 (12%)      9 (15%)                  
      Respiratory Epithelium, Metaplasia, Squamous     2 (4%)                    6 (10%)      1 (6%)       8 (13%)                  
      Vomeronasal Organ, Inflammation, Suppurative                               1 (2%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (55)         (12)         (60)         (17)         (60)         (16)         
      Atrophy                                                       1 (8%)                                                          
      Fibrosis                                                                   1 (2%)                                             
      Infiltration Cellular, Lymphocyte                                                       1 (6%)                    1 (6%)      
      Inflammation, Chronic                                                      2 (3%)                                             
      Inflammation, Chronic Active                     1 (2%)                    6 (10%)                                            
      Inflammation, Suppurative                                                  1 (2%)                    3 (5%)       1 (6%)      
      Mineralization                                   1 (2%)                    1 (2%)                                             
      Necrosis                                                                                             1 (2%)                   
      Nephropathy                                      1 (2%)                    1 (2%)                    2 (3%)       1 (6%)      
      Bilateral, Inflammation, Suppurative                          1 (8%)                                                          
      Bilateral, Papilla, Inflammation, Suppurative    1 (2%)                                                                       
      Bilateral, Pelvis, Dilatation                    1 (2%)                                                                       
      Cortex, Cyst                                     1 (2%)                    1 (2%)                    2 (3%)                   
      Cortex, Fibrosis                                 1 (2%)                                                                       
      Cortex, Inflammation, Chronic                                                                        1 (2%)                   
      Pelvis, Dilatation                               8 (15%)      1 (8%)       5 (8%)       1 (6%)       7 (12%)      2 (13%)     
      Pelvis, Inflammation, Chronic                                                                        1 (2%)                   
      Pelvis, Inflammation, Chronic Active                                       1 (2%)                                             
      Pelvis, Inflammation, Suppurative                2 (4%)                    1 (2%)                                             
      Renal Tubule, Mineralization                                                                         2 (3%)                   
   Ureter                                                                                                 (2)                       
      Inflammation, Suppurative                                                                            1 (50%)                  
   Urethra                                            (2)                       (4)                       (5)                       
      Calculus Micro Observation Only                  1 (50%)                   3 (75%)                   4 (80%)                  
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   17                                                              
NTP Experiment-Test: 05123-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            NICKEL OXIDE                                       Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 05:20:49  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE MALE                          0 MG/M3      O MG/M3      1.25MGM3     1.25MGM3     2.5MG/M3     2.5MG/M3        
                                                                  LUNGTX                    LUNGTX                    LUNGTX        
____________________________________________________________________________________________________________________________________
                                                                                                                                    
URINARY SYSTEM - CONT                                                                                                               
      Concretion                                       1 (50%)                   1 (25%)                   1 (20%)                  
   Urinary Bladder                                    (52)         (7)          (56)         (12)         (59)         (10)         
      Calculus Micro Observation Only                  1 (2%)       1 (14%)      3 (5%)                    3 (5%)                   
      Crystals                                                                   1 (2%)                                             
      Hemorrhage                                                                 1 (2%)                                             
      Inflammation                                                               1 (2%)                                             
      Inflammation, Chronic                            1 (2%)                    1 (2%)                    1 (2%)                   
      Inflammation, Chronic Active                     1 (2%)                    2 (4%)                    1 (2%)       1 (10%)     
      Inflammation, Suppurative                        2 (4%)                    5 (9%)                    2 (3%)                   
      Transitional Epithelium, Hyperplasia                          1 (14%)                                                         
      Transitional Epithelium, Metaplasia, Squamous    1 (2%)                                              1 (2%)                   
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   18                                                              
NTP Experiment-Test: 05123-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            NICKEL OXIDE                                       Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 05:20:49  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE MALE                          5.0MG/M3     5.0MG/M3                                                            
                                                                  LUNGTX                                                            
____________________________________________________________________________________________________________________________________
DISPOSITION SUMMARY                                                                                                                 
  Animals Initially In Study                          60           20                                                               
  Scheduled Sacrifice                                              10                                                               
  Early Deaths                                                                                                                      
    Moribund Sacrifice                                22            7                                                               
    Natural Death                                     15            2                                                               
  Survivors                                                                                                                         
    Terminal Sacrifice                                23                                                                            
    Terminal Sacrifice                                              1                                                               
  Animals Examined Microscopically                    60           19                                                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Gallbladder                                        (50)         (13)                                                             
      Inflammation, Chronic                            1 (2%)                                                                       
   Intestine Large, Cecum                             (52)         (13)                                                             
      Hyperplasia, Lymphoid                            2 (4%)                                                                       
   Liver                                              (60)         (14)                                                             
      Abscess                                          1 (2%)                                                                       
      Basophilic Focus                                 1 (2%)                                                                       
      Developmental Malformation                       1 (2%)                                                                       
      Eosinophilic Focus                               1 (2%)       1 (7%)                                                          
      Fatty Change                                     1 (2%)                                                                       
      Hematopoietic Cell Proliferation                 1 (2%)                                                                       
      Infarct                                          4 (7%)                                                                       
      Hepatocyte, Hyperplasia                          1 (2%)       1 (7%)                                                          
      Hepatocyte, Necrosis                             4 (7%)                                                                       
   Pancreas                                           (59)         (14)                                                             
      Cyst                                             1 (2%)                                                                       
   Stomach, Forestomach                               (58)         (14)                                                             
      Hyperkeratosis                                   1 (2%)                                                                       
   Stomach, Glandular                                 (58)         (14)                                                             
      Inflammation, Suppurative                        1 (2%)                                                                       
   Tooth                                              (1)                                                                           
      Dysplasia                                        1 (100%)                                                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Heart                                              (60)         (14)                                                             
      Inflammation, Chronic                            1 (2%)                                                                       
      Inflammation, Suppurative                        1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   19                                                              
NTP Experiment-Test: 05123-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            NICKEL OXIDE                                       Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 05:20:49  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE MALE                          5.0MG/M3     5.0MG/M3                                                            
                                                                  LUNGTX                                                            
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Cortex                                     (60)         (14)                                                             
      Cyst                                             1 (2%)                                                                       
      Hyperplasia                                      2 (3%)                                                                       
   Pituitary Gland                                    (57)         (14)                                                             
      Pars Distalis, Hyperplasia                       1 (2%)                                                                       
   Thyroid Gland                                      (60)         (14)                                                             
      Hyperplasia, Cystic                             25 (42%)      2 (14%)                                                         
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   Tissue NOS                                         (2)          (2)                                                              
      Hemorrhage                                       1 (50%)                                                                      
      Inflammation, Suppurative                        1 (50%)                                                                      
      Necrosis                                                      1 (50%)                                                         
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Epididymis                                         (59)         (14)                                                             
      Inflammation, Chronic                            2 (3%)                                                                       
      Inflammation, Chronic Active                                  1 (7%)                                                          
      Inflammation, Suppurative                        1 (2%)                                                                       
   Penis                                              (10)         (3)                                                              
      Concretion                                       4 (40%)      1 (33%)                                                         
      Inflammation                                     1 (10%)                                                                      
      Inflammation, Suppurative                        4 (40%)      2 (67%)                                                         
   Preputial Gland                                    (60)         (16)                                                             
      Atrophy                                          2 (3%)                                                                       
      Ectasia                                         19 (32%)      3 (19%)                                                         
      Inflammation, Chronic                            7 (12%)      2 (13%)                                                         
      Inflammation, Chronic Active                     2 (3%)                                                                       
      Inflammation, Suppurative                        9 (15%)      2 (13%)                                                         
      Bilateral, Ectasia                              36 (60%)      5 (31%)                                                         
      Duct, Concretion                                              2 (13%)                                                         
   Prostate                                           (57)         (13)                                                             
      Inflammation, Suppurative                        1 (2%)                                                                       
   Seminal Vesicle                                    (60)         (13)                                                             
      Cyst                                             1 (2%)                                                                       
      Dilatation                                       6 (10%)      4 (31%)                                                         
   Testes                                             (60)         (14)                                                             
      Atrophy                                          1 (2%)                                                                       
      Bilateral, Atrophy                               1 (2%)                                                                       
      Germinal Epithelium, Degeneration                1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   20                                                              
NTP Experiment-Test: 05123-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            NICKEL OXIDE                                       Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 05:20:49  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE MALE                          5.0MG/M3     5.0MG/M3                                                            
                                                                  LUNGTX                                                            
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Bone Marrow                                        (59)         (14)                                                             
      Erythroid Cell, Hyperplasia                      1 (2%)                                                                       
      Myeloid Cell, Hyperplasia                       10 (17%)      3 (21%)                                                         
      Myeloid Cell, Inflammation                       1 (2%)                                                                       
   Lymph Node                                         (12)         (4)                                                              
      Iliac, Hyperplasia, Lymphoid                     8 (67%)                                                                      
      Iliac, Pigmentation                              2 (17%)                                                                      
      Inguinal, Hyperplasia, Lymphoid                  6 (50%)      3 (75%)                                                         
   Lymph Node, Bronchial                              (55)         (16)                                                             
      Congestion                                       1 (2%)                                                                       
      Edema                                            1 (2%)                                                                       
      Hyperplasia, Lymphoid                           32 (58%)      5 (31%)                                                         
      Pigmentation                                    53 (96%)     16 (100%)                                                        
   Lymph Node, Mandibular                             (52)         (13)                                                             
      Hyperplasia, Lymphoid                            2 (4%)                                                                       
   Lymph Node, Mesenteric                             (54)         (14)                                                             
      Congestion                                       6 (11%)                                                                      
      Hematopoietic Cell Proliferation                 2 (4%)       1 (7%)                                                          
      Hyperplasia, Lymphoid                            3 (6%)                                                                       
      Inflammation, Suppurative                        1 (2%)                                                                       
   Lymph Node, Mediastinal                            (20)         (9)                                                              
      Congestion                                       2 (10%)                                                                      
      Pigmentation                                     1 (5%)                                                                       
   Spleen                                             (60)         (14)                                                             
      Hematopoietic Cell Proliferation                13 (22%)      4 (29%)                                                         
      Hyperplasia, Lymphoid                            4 (7%)                                                                       
      Thrombosis                                       2 (3%)                                                                       
   Thymus                                             (51)         (12)                                                             
      Atrophy                                          1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Skin                                               (22)         (5)                                                              
      Alopecia                                                      1 (20%)                                                         
      Cyst Epithelial Inclusion                        1 (5%)                                                                       
      Inflammation, Chronic Active                                  1 (20%)                                                         
      Inflammation, Suppurative                       11 (50%)      2 (40%)                                                         
      Necrosis                                         1 (5%)                                                                       
      Prepuce, Inflammation                            1 (5%)                                                                       
      Prepuce, Inflammation, Suppurative               3 (14%)      1 (20%)                                                         
      Subcutaneous Tissue, Fibrosis                    1 (5%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   21                                                              
NTP Experiment-Test: 05123-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            NICKEL OXIDE                                       Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 05:20:49  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE MALE                          5.0MG/M3     5.0MG/M3                                                            
                                                                  LUNGTX                                                            
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   Bone                                               (59)         (14)                                                             
      Fracture Healed                                  1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Lung                                               (60)         (19)                                                             
      Congestion                                                    1 (5%)                                                          
      Fibrosis                                         1 (2%)                                                                       
      Inflammation, Chronic                           48 (80%)     14 (74%)                                                         
      Alveolar Epithelium, Hyperplasia                35 (58%)      7 (37%)                                                         
      Alveolus, Pigmentation                          60 (100%)    18 (95%)                                                         
      Alveolus, Proteinosis                           37 (62%)      9 (47%)                                                         
   Nose                                               (58)         (19)                                                             
      Olfactory Epithelium, Degeneration               1 (2%)                                                                       
      Respiratory Epithelium, Degeneration             1 (2%)                                                                       
      Respiratory Epithelium, Inflammation,                                                                                         
          Suppurative                                  7 (12%)                                                                      
      Respiratory Epithelium, Metaplasia, Squamous     2 (3%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   Harderian Gland                                    (3)                                                                           
      Hyperplasia                                      1 (33%)                                                                      
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (59)         (19)                                                             
      Inflammation, Chronic                            1 (2%)                                                                       
      Inflammation, Chronic Active                     1 (2%)                                                                       
      Inflammation, Suppurative                        5 (8%)       1 (5%)                                                          
      Nephropathy                                      1 (2%)                                                                       
      Pelvis, Dilatation                               4 (7%)       1 (5%)                                                          
      Pelvis, Hyperplasia, Squamous                    1 (2%)                                                                       
      Pelvis, Inflammation, Chronic Active             1 (2%)                                                                       
      Pelvis, Inflammation, Suppurative                             1 (5%)                                                          
   Ureter                                             (3)          (1)                                                              
      Concretion                                       2 (67%)                                                                      
      Inflammation, Chronic Active                     1 (33%)                                                                      
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   22                                                              
NTP Experiment-Test: 05123-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                            NICKEL OXIDE                                       Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 05:20:49  
____________________________________________________________________________________________________________________________________
         B6C3F1 MICE MALE                          5.0MG/M3     5.0MG/M3                                                            
                                                                  LUNGTX                                                            
____________________________________________________________________________________________________________________________________
                                                                                                                                    
URINARY SYSTEM - CONT                                                                                                               
      Inflammation, Suppurative                                     1 (100%)                                                        
   Urethra                                            (11)         (1)                                                              
      Calculus Micro Observation Only                  7 (64%)      1 (100%)                                                        
      Concretion                                       4 (36%)                                                                      
   Urinary Bladder                                    (57)         (14)                                                             
      Calculus Gross Observation                       1 (2%)                                                                       
      Calculus Micro Observation Only                  1 (2%)                                                                       
      Inflammation, Chronic Active                     1 (2%)                                                                       
      Inflammation, Suppurative                        3 (5%)       1 (7%)                                                          
      Transitional Epithelium, Hyperplasia             3 (5%)                                                                       
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   23                                                              
                             ------------------------------------------------------------                                           
                             ----------              END OF REPORT             ----------                                           
                             ------------------------------------------------------------                                           
NTP is located at the National Institute of Environmental Health Sciences, part of the National Institutes of Health.