National Toxicology Program

National Toxicology Program
https://ntp.niehs.nih.gov/go/3450

TDMS Study 05040-02 Pathology Tables


                              INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)
                                                            HYDROQUINONE


NTP Experiment-Test: 05040-02                                                                                     Report: PEIRPT05
Study Type: CHRONIC                                                                                               Date: 09/05/94
Route: GAVAGE                                                                                                     Time: 11:58:40




       Facility:  American Biogenics Corp.

       Chemical CAS #:  000123319

       Lock Date:  None

       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: 05040-02  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                            HYDROQUINONE                                       Date: 09/05/94  
Route: GAVAGE                                                                                                     Time: 11:58:40  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         B6C3F1 MICE FEMALE                        VEHICLE      50 MG/KG     100MG/KG                                               
                                                   CONTROL                                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
DISPOSITION SUMMARY                                                                                                                 
  Animals Initially in Study                          65           65           65                                                  
  Scheduled Sacrifice                                 10           10           10                                                  
  Early Deaths                                                                                                                      
    Moribund                                           7           11            6                                                  
    Dead                                              11            5            9                                                  
    Accident                                                                     4                                                  
  Survivors                                                                                                                         
    Terminal Sacrifice                                37           39           36                                                  
  Animals Examined Microscopically                    55           55           55                                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Gallbladder                                        (50)         (12)         (48)                                                
   Intestine Large, Cecum                             (52)         (13)         (53)                                                
   Intestine Large, Colon                             (52)         (14)         (52)                                                
   Intestine Small, Duodenum                          (52)         (15)         (51)                                                
      Serosa, Fibrosarcoma, Metastatic, Mesentery                   1 (7%)                                                          
   Intestine Small, Ileum                             (49)         (14)         (52)                                                
   Intestine Small, Jejunum                           (52)         (12)         (52)                                                
   Liver                                              (55)         (55)         (55)                                                
      Cholangiocarcinoma, Metastatic                                1 (2%)                                                          
      Hemangioma                                       1 (2%)       1 (2%)                                                          
      Hemangiosarcoma                                  1 (2%)                                                                       
      Hepatocellular Carcinoma                         1 (2%)       2 (4%)       2 (4%)                                             
      Hepatocellular Adenoma                           2 (4%)      11 (20%)     11 (20%)                                            
      Hepatocellular Adenoma, Multiple                              4 (7%)       1 (2%)                                             
      Histiocytic Sarcoma                                                        1 (2%)                                             
   Mesentery                                          (19)         (12)         (4)                                                 
      Cholangiocarcinoma, Metastatic                                1 (8%)                                                          
      Fibrosarcoma                                                  1 (8%)                                                          
      Fibrosarcoma, Multiple                                        1 (8%)                                                          
   Pancreas                                           (54)         (16)         (53)                                                
      Fibrosarcoma, Early Invasion, Metastatic,                                                                                     
           Mesentery                                                1 (6%)                                                          
   Salivary Glands                                    (54)         (54)         (54)                                                
      Histiocytic Sarcoma                                                        1 (2%)                                             
   Stomach                                            (54)         (17)         (55)                                                
   Stomach, Forestomach                               (54)         (17)         (55)                                                
      Squamous Cell Papilloma                                       1 (6%)                                                          
   Stomach, Glandular                                 (53)         (16)         (55)                                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
                                                             Page   2                                                               
NTP Experiment-Test: 05040-02  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                            HYDROQUINONE                                       Date: 09/05/94  
Route: GAVAGE                                                                                                     Time: 11:58:40  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         B6C3F1 MICE FEMALE                        VEHICLE      50 MG/KG     100MG/KG                                               
                                                   CONTROL                                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Heart                                              (55)         (17)         (55)                                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Gland                                      (55)         (13)         (55)                                                
      Capsule, Cholangiocarcinoma, Metastatic                       1 (8%)                                                          
   Adrenal Gland, Cortex                              (55)         (13)         (55)                                                
   Adrenal Gland, Medulla                             (51)         (11)         (52)                                                
      Pheochromocytoma Malignant                       1 (2%)                                                                       
      Pheochromocytoma Benign                          1 (2%)                                                                       
   Islets, Pancreatic                                 (51)         (15)         (52)                                                
   Pituitary Gland                                    (52)         (29)         (52)                                                
      Pars Distalis, Adenoma                          11 (21%)     14 (48%)     11 (21%)                                            
      Pars Distalis, Carcinoma                         1 (2%)       2 (7%)                                                          
      Pars Intermedia, Adenoma                         1 (2%)                    1 (2%)                                             
   Thyroid Gland                                      (55)         (55)         (55)                                                
      Follicular Cell, Adenoma                         3 (5%)       5 (9%)       6 (11%)                                            
      Follicular Cell, Carcinoma                                                 1 (2%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   Tissue NOS                                         (1)                       (1)                                                 
      Sarcoma, Poorly Differentiated                   1 (100%)                                                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Ovary                                              (55)         (53)         (54)                                                
      Adenoma                                                       1 (2%)                                                          
      Cystadenoma                                                                1 (2%)                                             
      Osteosarcoma, Metastatic, Bone                                1 (2%)                                                          
      Teratoma                                         1 (2%)                                                                       
   Uterus                                             (54)         (29)         (55)                                                
      Hemangioma                                                    1 (3%)                                                          
      Polyp Stromal                                                 1 (3%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Bone Marrow                                        (55)         (16)         (54)                                                
   Lymph Node                                         (55)         (22)         (54)                                                
      Lumbar, Osteosarcoma, Metastatic, Bone                        1 (5%)                                                          
      Pancreatic, Histiocytic Sarcoma                                            1 (2%)                                             
   Lymph Node, Mandibular                             (50)         (16)         (49)                                                
                                                             Page   3                                                               
NTP Experiment-Test: 05040-02  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                            HYDROQUINONE                                       Date: 09/05/94  
Route: GAVAGE                                                                                                     Time: 11:58:40  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         B6C3F1 MICE FEMALE                        VEHICLE      50 MG/KG     100MG/KG                                               
                                                   CONTROL                                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
HEMATOPOIETIC SYSTEM - cont                                                                                                         
      Histiocytic Sarcoma                                                        1 (2%)                                             
   Lymph Node, Mesenteric                             (52)         (17)         (52)                                                
      Histiocytic Sarcoma                                                        1 (2%)                                             
      Renal, Cholangiocarcinoma, Metastatic                         1 (6%)                                                          
   Spleen                                             (55)         (22)         (55)                                                
      Capsule, Cholangiocarcinoma, Metastatic                       1 (5%)                                                          
   Thymus                                             (44)         (13)         (47)                                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Mammary Gland                                      (52)         (20)         (53)                                                
      Adenocarcinoma                                   3 (6%)       5 (25%)      2 (4%)                                             
      Cholangiocarcinoma, Multiple, Metastatic                      1 (5%)                                                          
      Thoracic, Hepatocellular Carcinoma,                                                                                           
          Metastatic, Liver                                         1 (5%)                                                          
   Skin                                               (55)         (16)         (55)                                                
      Basal Cell Carcinoma                             1 (2%)                                                                       
      Subcutaneous Tissue, Fibrosarcoma                1 (2%)       1 (6%)                                                          
      Subcutaneous Tissue, Hepatocellular                                                                                           
          Carcinoma, Metastatic, Liver                              1 (6%)                                                          
      Tail, Neurofibrosarcoma                          1 (2%)                                                                       
      Thoracic, Subcutaneous Tissue,                                                                                                
          Hemangiosarcoma                                                        1 (2%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   Bone                                               (55)         (16)         (55)                                                
      Lumbar, Vertebra, Osteosarcoma                                1 (6%)                                                          
      Vertebra, Cholangiocarcinoma, Metastatic                      1 (6%)                                                          
   Skeletal Muscle                                                 (2)          (1)                                                 
      Abdominal, Fibrosarcoma, Early Invasion,                                                                                      
           Metastatic, Mesentery                                    1 (50%)                                                         
      Abdominal, Diaphragm, Cholangiocarcinoma,                                                                                     
           Metastatic                                               1 (50%)                                                         
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (55)         (16)         (55)                                                
      Carcinoma, Extension, Metastatic, Pituitary                                                                                   
          Gland                                        1 (2%)       1 (6%)                                                          
      Cerebrum, Oligodendroglioma Malignant            1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
                                                             Page   4                                                               
NTP Experiment-Test: 05040-02  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                            HYDROQUINONE                                       Date: 09/05/94  
Route: GAVAGE                                                                                                     Time: 11:58:40  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         B6C3F1 MICE FEMALE                        VEHICLE      50 MG/KG     100MG/KG                                               
                                                   CONTROL                                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Lung                                               (55)         (55)         (55)                                                
      Alveolar/Bronchiolar Adenoma                     3 (5%)       6 (11%)      1 (2%)                                             
      Alveolar/Bronchiolar Adenoma, Multiple                                     1 (2%)                                             
      Alveolar/Bronchiolar Carcinoma                   1 (2%)                    2 (4%)                                             
      Basal Cell Carcinoma, Metastatic                 1 (2%)                                                                       
      Carcinoma, Metastatic                                                      1 (2%)                                             
      Hepatocellular Carcinoma, Metastatic, Liver                   1 (2%)                                                          
      Osteosarcoma, Metastatic, Bone                                1 (2%)                                                          
   Trachea                                            (54)         (16)         (55)                                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   Ear                                                (1)                                                                           
      Canal, External Ear, Squamous Cell Carcinoma     1 (100%)                                                                     
   Harderian Gland                                    (3)          (3)          (7)                                                 
      Adenoma                                          2 (67%)      2 (67%)      2 (29%)                                            
      Carcinoma                                                                  2 (29%)                                            
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (55)         (16)         (55)                                                
      Hepatocellular Carcinoma, Metastatic                          1 (6%)                                                          
      Osteosarcoma, Metastatic, Bone                                1 (6%)                                                          
      Capsule, Cholangiocarcinoma, Metastatic                       1 (6%)                                                          
      Renal Tubule, Adenoma                            1 (2%)                    1 (2%)                                             
   Urinary Bladder                                    (53)         (15)         (54)                                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SYSTEMIC LESIONS                                                                                                                   
   Multiple Organs                                   *(55)        *(55)        *(55)                                                
      Histiocytic Sarcoma                                                        1 (2%)                                             
      Lymphoma Malignant                               3 (5%)       1 (2%)       3 (5%)                                             
      Lymphoma Malignant Histiocytic                                1 (2%)       1 (2%)                                             
      Lymphoma Malignant Lymphocytic                  14 (25%)      7 (13%)      9 (16%)                                            
      Lymphoma Malignant Mixed                         7 (13%)      5 (9%)       6 (11%)                                            
      Lymphoma Malignant Undifferentiated Cell                                   1 (2%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
     *   Number of animals with any tissue examined microscopically                                                                 
                                                             Page   5                                                               
NTP Experiment-Test: 05040-02  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                            HYDROQUINONE                                       Date: 09/05/94  
Route: GAVAGE                                                                                                     Time: 11:58:40  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         B6C3F1 MICE FEMALE                        VEHICLE      50 MG/KG     100MG/KG                                               
                                                   CONTROL                                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
TUMOR SUMMARY                                                                                                                       
                                                                                                                                    
   Total Animals with Primary Neoplasms (b)            43          42          39                                                   
     Total Primary Neoplasms                           64          76          67                                                   
                                                                                                                                    
   Total Animals with Benign Neoplasms                 21          33          27                                                   
     Total Benign Neoplasms                            26          47          36                                                   
                                                                                                                                    
   Total Animals with Malignant Neoplasms              31          21          27                                                   
     Total Malignant Neoplasms                         38          29          31                                                   
                                                                                                                                    
   Total Animals with Metastatic Neoplasms              2           4           1                                                   
     Total Metastatic Neoplasm                          2          21           1                                                   
                                                                                                                                    
   Total Animals with Malignant Neoplasms                                                                                           
   Uncertain Primary Site                                                                                                           
                                                                                                                                    
   Total Animals with Neoplasms Uncertain-                                                                                          
   Benign or Malignant                                                                                                              
     Total Uncertain Neoplasms                                                                                                      
                                                                                                                                    
____________________________________________________________________________________________________________________________________
a  Number of animals examined microscopically at site and number of animals with lesion                                             
b  Primary tumors: all tumors except metastatic tumors                                                                              
                                                             Page   6                                                               
NTP Experiment-Test: 05040-02  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                            HYDROQUINONE                                       Date: 09/05/94  
Route: GAVAGE                                                                                                     Time: 11:58:40  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         B6C3F1 MICE MALE                          VEHICLE      50 MG/KG     100MG/KG                                               
                                                   CONTROL                                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
DISPOSITION SUMMARY                                                                                                                 
  Animals Initially in Study                          65           65           65                                                  
  Scheduled Sacrifice                                 10           10           10                                                  
  Early Deaths                                                                                                                      
    Moribund                                          12           10            5                                                  
    Dead                                              10            7           14                                                  
  Survivors                                                                                                                         
    Terminal Sacrifice                                33           37           36                                                  
  Wrong Sex                                                         1                                                               
  Animals Examined Microscopically                    55           54           55                                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Gallbladder                                        (44)         (11)         (48)                                                
   Intestine Large, Cecum                             (49)         (13)         (49)                                                
   Intestine Large, Colon                             (49)         (14)         (48)                                                
   Intestine Large, Rectum                            (50)         (15)         (52)                                                
      Serosa, Carcinoid Tumor Benign                                             1 (2%)                                             
   Intestine Small, Ileum                             (48)         (10)         (47)                                                
      Adenocarcinoma                                   1 (2%)                                                                       
   Intestine Small, Jejunum                           (50)         (13)         (45)                                                
   Liver                                              (55)         (54)         (55)                                                
      Fibrosarcoma, Metastatic, Skin                   1 (2%)                                                                       
      Hemangioma                                                                 1 (2%)                                             
      Hemangioma, Marked                               1 (2%)                                                                       
      Hemangiosarcoma                                  1 (2%)       1 (2%)       2 (4%)                                             
      Hepatocellular Carcinoma                        12 (22%)     11 (20%)      7 (13%)                                            
      Hepatocellular Carcinoma, Multiple               1 (2%)                                                                       
      Hepatocellular Adenoma                           9 (16%)     15 (28%)     15 (27%)                                            
      Hepatocellular Adenoma, Multiple                              6 (11%)      5 (9%)                                             
      Sinusoid, Sarcoma                                             1 (2%)                                                          
   Mesentery                                          (6)          (4)          (5)                                                 
      Alveolar/Bronchiolar Carcinoma, Metastatic,                                                                                   
           Lung                                        1 (17%)                                                                      
   Pancreas                                           (54)         (15)         (53)                                                
   Salivary Glands                                    (55)         (16)         (55)                                                
   Stomach, Forestomach                               (55)         (15)         (53)                                                
      Squamous Cell Papilloma                          2 (4%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
                                                             Page   7                                                               
NTP Experiment-Test: 05040-02  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                            HYDROQUINONE                                       Date: 09/05/94  
Route: GAVAGE                                                                                                     Time: 11:58:40  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         B6C3F1 MICE MALE                          VEHICLE      50 MG/KG     100MG/KG                                               
                                                   CONTROL                                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Heart                                              (55)         (17)         (55)                                                
      Alveolar/Bronchiolar Carcinoma, Metastatic,                                                                                   
           Lung                                        1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Gland                                      (55)         (53)         (54)                                                
   Adrenal Gland, Cortex                              (55)         (52)         (54)                                                
      Adenoma                                          2 (4%)       2 (4%)                                                          
   Adrenal Gland, Medulla                             (54)         (52)         (54)                                                
      Pheochromocytoma Benign                          1 (2%)       3 (6%)                                                          
   Pituitary Gland                                    (50)         (14)         (50)                                                
      Pars Distalis, Adenoma                           3 (6%)                                                                       
   Thyroid Gland                                      (55)         (53)         (54)                                                
      Follicular Cell, Adenoma                         2 (4%)       1 (2%)       2 (4%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   Tissue NOS                                                      (1)          (1)                                                 
      Carcinoma                                                     1 (100%)                                                        
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Epididymis                                         (54)         (17)         (54)                                                
   Prostate                                           (55)         (17)         (55)                                                
   Seminal Vesicle                                    (55)         (17)         (55)                                                
   Testes                                             (55)         (18)         (55)                                                
      Interstitial Cell, Adenoma                       1 (2%)                    3 (5%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Lymph Node                                         (55)         (29)         (55)                                                
      Alveolar/Bronchiolar Carcinoma, Metastatic,                                                                                   
           Lung                                                                  1 (2%)                                             
   Lymph Node, Mandibular                             (52)         (17)         (51)                                                
   Lymph Node, Mesenteric                             (54)         (23)         (50)                                                
   Spleen                                             (55)         (52)         (54)                                                
   Thymus                                             (39)         (10)         (42)                                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
                                                             Page   8                                                               
NTP Experiment-Test: 05040-02  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                            HYDROQUINONE                                       Date: 09/05/94  
Route: GAVAGE                                                                                                     Time: 11:58:40  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         B6C3F1 MICE MALE                          VEHICLE      50 MG/KG     100MG/KG                                               
                                                   CONTROL                                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Skin                                               (55)         (33)         (55)                                                
      Fibroma                                          1 (2%)       1 (3%)                                                          
      Fibrosarcoma                                     2 (4%)       1 (3%)       1 (2%)                                             
      Squamous Cell Papilloma                          1 (2%)                                                                       
      Subcutaneous Tissue, Fibroma                     1 (2%)       1 (3%)                                                          
      Subcutaneous Tissue, Fibroma, Multiple                        1 (3%)                                                          
      Subcutaneous Tissue, Fibrosarcoma                5 (9%)       8 (24%)      2 (4%)                                             
      Subcutaneous Tissue, Hemangiosarcoma                                       1 (2%)                                             
      Subcutaneous Tissue, Neurofibroma                1 (2%)                                                                       
      Subcutaneous Tissue, Sarcoma                     1 (2%)       3 (9%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   Bone                                               (54)         (32)         (55)                                                
      Osteosarcoma                                     1 (2%)                                                                       
   Skeletal Muscle                                    (3)                                                                           
      Intercostal, Alveolar/Bronchiolar Carcinoma,                                                                                  
           Metastatic, Lung                            1 (33%)                                                                      
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (55)         (17)         (55)                                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Lung                                               (55)         (31)         (55)                                                
      Alveolar/Bronchiolar Adenoma                     5 (9%)       9 (29%)      3 (5%)                                             
      Alveolar/Bronchiolar Adenoma, Multiple           1 (2%)                    1 (2%)                                             
      Alveolar/Bronchiolar Carcinoma                   8 (15%)      4 (13%)      6 (11%)                                            
      Hepatocellular Carcinoma, Metastatic, Liver      5 (9%)                    3 (5%)                                             
   Nose                                               (55)         (17)         (55)                                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   Ear                                                             (1)                                                              
      Pinna, Histiocytic Sarcoma                                    1 (100%)                                                        
   Harderian Gland                                    (5)          (2)          (7)                                                 
      Adenoma                                          5 (100%)     2 (100%)     6 (86%)                                            
____________________________________________________________________________________________________________________________________
                                                                                                                                    
                                                             Page   9                                                               
NTP Experiment-Test: 05040-02  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                            HYDROQUINONE                                       Date: 09/05/94  
Route: GAVAGE                                                                                                     Time: 11:58:40  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         B6C3F1 MICE MALE                          VEHICLE      50 MG/KG     100MG/KG                                               
                                                   CONTROL                                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (55)         (17)         (55)                                                
      Renal Tubule, Carcinoma                                                    1 (2%)                                             
   Urinary Bladder                                    (54)         (15)         (55)                                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SYSTEMIC LESIONS                                                                                                                   
   Multiple Organs                                   *(55)        *(54)        *(55)                                                
      Histiocytic Sarcoma                                           1 (2%)                                                          
      Lymphoma Malignant Histiocytic                   2 (4%)                    2 (4%)                                             
      Lymphoma Malignant Lymphocytic                   4 (7%)       9 (17%)      4 (7%)                                             
      Lymphoma Malignant Mixed                                      2 (4%)       1 (2%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
     *   Number of animals with any tissue examined microscopically                                                                 
                                                             Page  10                                                               
NTP Experiment-Test: 05040-02  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                            HYDROQUINONE                                       Date: 09/05/94  
Route: GAVAGE                                                                                                     Time: 11:58:40  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         B6C3F1 MICE MALE                          VEHICLE      50 MG/KG     100MG/KG                                               
                                                   CONTROL                                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
TUMOR SUMMARY                                                                                                                       
                                                                                                                                    
   Total Animals with Primary Neoplasms (b)            39          46          44                                                   
     Total Primary Neoplasms                           79          84          69                                                   
                                                                                                                                    
   Total Animals with Benign Neoplasms                 23          31          29                                                   
     Total Benign Neoplasms                            38          41          41                                                   
                                                                                                                                    
   Total Animals with Malignant Neoplasms              30          34          23                                                   
     Total Malignant Neoplasms                         41          43          28                                                   
                                                                                                                                    
   Total Animals with Metastatic Neoplasms              7                       4                                                   
     Total Metastatic Neoplasm                          9                       4                                                   
                                                                                                                                    
   Total Animals with Malignant Neoplasms                                                                                           
   Uncertain Primary Site                                                                                                           
                                                                                                                                    
   Total Animals with Neoplasms Uncertain-                                                                                          
   Benign or Malignant                                                                                                              
     Total Uncertain Neoplasms                                                                                                      
                                                                                                                                    
____________________________________________________________________________________________________________________________________
a  Number of animals examined microscopically at site and number of animals with lesion                                             
b  Primary tumors: all tumors except metastatic tumors                                                                              
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NTP is located at the National Institute of Environmental Health Sciences, part of the National Institutes of Health.