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TDMS Study 05150-02 Pathology Tables


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


NTP Experiment-Test: 05150-02                                                                                     Report: PEIRPT05
Study Type: CHRONIC                                                                                               Date: 05/20/95
Route: DOSED FEED                                                                                                 Time: 09:59:05




       Facility:  TSI Mason Research

       Chemical CAS #:  298-59-9

       Lock Date:  02/19/92

       Cage Range:  All

       Reasons For Removal:    All

       Removal Date Range:     All

       Treatment Groups:       Include All
































a  Number of animals examined microscopically at site and number of animals with lesion

                                                             Page   1

NTP Experiment-Test: 05150-02  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 05/20/95  
Route: DOSED FEED                                                                                                 Time: 09:59:05  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         B6C3F1 MICE FEMALE                        0 PPM        50 PPM       250 PPM      500 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
DISPOSITION SUMMARY                                                                                                                 
  Animals Initially in Study                          69           69           70           70                                     
  Scheduled Sacrifice                                 20           19           20           20                                     
  Early Deaths                                                                                                                      
    Natural Death                                      5            7            6                                                  
    Accidently Killed                                  1                                                                            
    Moribund Sacrifice                                 6            7            7            6                                     
  Survivors                                                                                                                         
    Terminal Sacrifice                                36           34           37           44                                     
    Natural Death                                      1            1                                                               
  Missing                                                           1                                                               
  Animals Examined Microscopically                    69           68           70           70                                     
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Gallbladder                                        (64)         (56)         (63)         (68)                                   
   Intestine Large, Rectum                            (65)         (65)         (67)         (70)                                   
   Intestine Large, Cecum                             (67)         (63)         (65)         (70)                                   
   Intestine Small, Duodenum                          (65)         (62)         (65)         (70)                                   
      Polyp Adenomatous                                1 (2%)                                                                       
   Intestine Small, Jejunum                           (65)         (63)         (65)         (70)                                   
      Adenocarcinoma                                                1 (2%)                                                          
      Hemangioma                                                                 1 (2%)                                             
   Intestine Small, Ileum                             (65)         (61)         (65)         (69)                                   
   Liver                                              (69)         (67)         (69)         (70)                                   
      Hemangioma                                       1 (1%)                                                                       
      Hemangiosarcoma                                  1 (1%)       1 (1%)       1 (1%)                                             
      Hepatocellular Carcinoma                         3 (4%)       3 (4%)       2 (3%)       5 (7%)                                
      Hepatocellular Carcinoma, Multiple               2 (3%)                                 1 (1%)                                
      Hepatocellular Adenoma                           5 (7%)      11 (16%)      8 (12%)     14 (20%)                               
      Hepatocellular Adenoma, Multiple                 2 (3%)                    3 (4%)      15 (21%)                               
      Histiocytic Sarcoma                                           1 (1%)       1 (1%)                                             
      Histiocytic Sarcoma, Metastatic, Uterus                                    1 (1%)                                             
   Mesentery                                          (6)                       (1)          (2)                                    
      Sarcoma                                          1 (17%)                                                                      
   Pancreas                                           (68)         (67)         (69)         (70)                                   
   Salivary Glands                                    (69)         (67)         (70)         (69)                                   
   Stomach, Forestomach                               (67)         (68)         (69)         (70)                                   
      Squamous Cell Papilloma                          1 (1%)       1 (1%)       1 (1%)                                             
   Stomach, Glandular                                 (68)         (65)         (68)         (70)                                   
____________________________________________________________________________________________________________________________________
                                                                                                                                    
                                                             Page   2                                                               
NTP Experiment-Test: 05150-02  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 05/20/95  
Route: DOSED FEED                                                                                                 Time: 09:59:05  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         B6C3F1 MICE FEMALE                        0 PPM        50 PPM       250 PPM      500 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Heart                                              (68)         (68)         (69)         (70)                                   
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Cortex                                     (69)         (67)         (68)         (70)                                   
      Adenocarcinoma, Metastatic, Uterus                                                      1 (1%)                                
      Alveolar/Bronchiolar Carcinoma, Metastatic,                                                                                   
           Lung                                                                  1 (1%)                                             
      Capsule, Adenoma                                                                        1 (1%)                                
   Adrenal Medulla                                    (67)         (64)         (66)         (68)                                   
      Pheochromocytoma Malignant                                                 1 (2%)                                             
      Pheochromocytoma Benign                                                                 1 (1%)                                
   Islets, Pancreatic                                 (68)         (67)         (69)         (70)                                   
      Adenoma                                          1 (1%)       2 (3%)       2 (3%)       1 (1%)                                
   Pituitary Gland                                    (67)         (66)         (68)         (67)                                   
      Pars Distalis, Adenoma                           7 (10%)     10 (15%)     15 (22%)      9 (13%)                               
      Pars Intermedia, Adenoma                         1 (1%)                                 1 (1%)                                
   Thyroid Gland                                      (69)         (66)         (68)         (69)                                   
      Follicular Cell, Adenoma                                      6 (9%)                    4 (6%)                                
      Follicular Cell, Carcinoma                                                 1 (1%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   Tissue NOS                                         (2)                                                                           
      Hemangiosarcoma                                  1 (50%)                                                                      
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Ovary                                              (65)         (67)         (69)         (67)                                   
      Cystadenoma                                      2 (3%)       4 (6%)       1 (1%)       2 (3%)                                
      Cystadenoma, Multiple                                         1 (1%)                                                          
      Histiocytic Sarcoma, Metastatic, Uterus                                    1 (1%)                                             
      Teratoma NOS                                     1 (2%)       1 (1%)                                                          
   Uterus                                             (69)         (68)         (69)         (70)                                   
      Hemangioma                                       1 (1%)                    1 (1%)                                             
      Histiocytic Sarcoma                              2 (3%)                    1 (1%)       1 (1%)                                
      Leiomyoma                                        1 (1%)                                                                       
      Polyp Stromal                                    2 (3%)                    6 (9%)       1 (1%)                                
      Endometrium, Adenocarcinoma                                                             1 (1%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
                                                             Page   3                                                               
NTP Experiment-Test: 05150-02  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 05/20/95  
Route: DOSED FEED                                                                                                 Time: 09:59:05  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         B6C3F1 MICE FEMALE                        0 PPM        50 PPM       250 PPM      500 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Bone Marrow                                        (69)         (68)         (67)         (70)                                   
      Adenocarcinoma, Metastatic, Uterus                                                      1 (1%)                                
      Hemangiosarcoma                                                            1 (1%)                                             
      Histiocytic Sarcoma                                           1 (1%)                                                          
   Lymph Node                                         (7)          (7)          (8)          (5)                                    
      Lumbar, Histiocytic Sarcoma, Metastatic,                                                                                      
           Uterus                                                                1 (13%)                                            
      Lumbar, Sarcoma, Metastatic, Skin                                          1 (13%)                                            
   Lymph Node, Mandibular                             (67)         (61)         (68)         (68)                                   
      Carcinoma, Metastatic, Harderian Gland                                                  1 (1%)                                
      Histiocytic Sarcoma                                                        1 (1%)                                             
      Histiocytic Sarcoma, Metastatic, Uterus                                    1 (1%)                                             
   Lymph Node, Mesenteric                             (65)         (66)         (67)         (67)                                   
      Histiocytic Sarcoma                                                        1 (1%)                                             
      Histiocytic Sarcoma, Metastatic, Uterus                                    1 (1%)                                             
   Spleen                                             (68)         (67)         (68)         (70)                                   
      Hemangioma                                                                 1 (1%)                                             
      Hemangiosarcoma                                  2 (3%)                    1 (1%)                                             
      Histiocytic Sarcoma                                           1 (1%)       1 (1%)                                             
   Thymus                                             (65)         (66)         (67)         (69)                                   
      Adenocarcinoma, Metastatic, Uterus                                                      1 (1%)                                
      Alveolar/Bronchiolar Carcinoma, Metastatic,                                                                                   
           Lung                                                                  1 (1%)                                             
      Histiocytic Sarcoma                                                        1 (1%)                                             
      Histiocytic Sarcoma, Metastatic, Uterus                                    1 (1%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Mammary Gland                                      (59)         (60)         (63)         (64)                                   
      Adenocarcinoma                                                             1 (2%)                                             
      Adenocarcinoma, Metastatic, Uterus                                                      1 (2%)                                
      Adenoma                                                                    1 (2%)                                             
   Skin                                               (69)         (68)         (70)         (70)                                   
      Hemangiosarcoma                                                            1 (1%)                                             
      Histiocytic Sarcoma                                                                     1 (1%)                                
      Sarcoma                                                       1 (1%)       1 (1%)       1 (1%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   Bone                                               (69)         (68)         (70)         (70)                                   
      Alveolar/Bronchiolar Carcinoma, Metastatic,                                                                                   
           Lung                                                                  1 (1%)                                             
   Skeletal Muscle                                    (1)                                                                           
____________________________________________________________________________________________________________________________________
                                                             Page   4                                                               
NTP Experiment-Test: 05150-02  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 05/20/95  
Route: DOSED FEED                                                                                                 Time: 09:59:05  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         B6C3F1 MICE FEMALE                        0 PPM        50 PPM       250 PPM      500 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (69)         (68)         (70)         (70)                                   
      Adenocarcinoma, Metastatic, Uterus                                                      1 (1%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Lung                                               (68)         (68)         (69)         (70)                                   
      Adenocarcinoma, Metastatic, Uterus                                                      1 (1%)                                
      Alveolar/Bronchiolar Adenoma                     2 (3%)       1 (1%)       4 (6%)       6 (9%)                                
      Alveolar/Bronchiolar Carcinoma                                             2 (3%)       2 (3%)                                
      Alveolar/Bronchiolar Carcinoma, Metastatic,                                                                                   
           Lung                                                                  1 (1%)                                             
      Carcinoma, Metastatic, Harderian Gland                                                  1 (1%)                                
      Carcinoma, Metastatic, Thyroid Gland                                       1 (1%)                                             
      Hepatocellular Carcinoma, Metastatic, Liver      2 (3%)                                 1 (1%)                                
      Histiocytic Sarcoma, Metastatic, Uterus                                    1 (1%)                                             
      Osteosarcoma, Metastatic, Uncertain Primary                                                                                   
          Site                                                      1 (1%)                                                          
      Sarcoma, Metastatic, Skin                                                  1 (1%)                                             
   Nose                                               (69)         (68)         (70)         (70)                                   
      Carcinoma, Metastatic, Harderian Gland                                                  1 (1%)                                
      Histiocytic Sarcoma, Metastatic, Uterus                                    1 (1%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   Harderian Gland                                    (2)          (1)          (4)          (5)                                    
      Adenoma                                          1 (50%)                   3 (75%)      1 (20%)                               
      Carcinoma                                                     1 (100%)                  3 (60%)                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (69)         (67)         (70)         (70)                                   
      Adenocarcinoma, Metastatic, Uterus                                                      1 (1%)                                
   Urinary Bladder                                    (63)         (59)         (64)         (70)                                   
      Hemangioma                                                                              1 (1%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SYSTEMIC LESIONS                                                                                                                   
   Multiple Organs                                   *(69)        *(68)        *(70)        *(70)                                   
      Histiocytic Sarcoma                              2 (3%)       1 (1%)       2 (3%)       2 (3%)                                
      Lymphoma Malignant Lymphocytic                   1 (1%)       1 (1%)       2 (3%)       3 (4%)                                
      Lymphoma Malignant Mixed                        11 (16%)     12 (18%)      6 (9%)      14 (20%)                               
                                                                                                                                    
     *   Number of animals with any tissue examined microscopically                                                                 
                                                             Page   5                                                               
NTP Experiment-Test: 05150-02  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 05/20/95  
Route: DOSED FEED                                                                                                 Time: 09:59:05  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         B6C3F1 MICE FEMALE                        0 PPM        50 PPM       250 PPM      500 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
                                                                                                                                    
 SYSTEMIC LESIONS - cont                                                                                                            
   Multiple Organs                                   *(69)        *(68)        *(70)        *(70)                                   
____________________________________________________________________________________________________________________________________
                                                             Page   6                                                               
NTP Experiment-Test: 05150-02  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 05/20/95  
Route: DOSED FEED                                                                                                 Time: 09:59:05  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         B6C3F1 MICE FEMALE                        0 PPM        50 PPM       250 PPM      500 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
TUMOR SUMMARY                                                                                                                       
                                                                                                                                    
   Total Animals with Primary Neoplasms (b)            37          36          41          44                                       
     Total Primary Neoplasms                           53          58          69          89                                       
                                                                                                                                    
   Total Animals with Benign Neoplasms                 22          26          31          38                                       
     Total Benign Neoplasms                            28          36          47          57                                       
                                                                                                                                    
   Total Animals with Malignant Neoplasms              22          20          16          26                                       
     Total Malignant Neoplasms                         24          21          22          32                                       
                                                                                                                                    
   Total Animals with Metastatic Neoplasms              2           1           4           3                                       
     Total Metastatic Neoplasm                          2           1          15          11                                       
                                                                                                                                    
   Total Animals with Malignant Neoplasms                           1                                                               
   Uncertain Primary Site                                                                                                           
                                                                                                                                    
   Total Animals with Neoplasms Uncertain-                                                                                          
   Benign or Malignant                                  1           1                                                               
     Total Uncertain Neoplasms                          1           1                                                               
                                                                                                                                    
____________________________________________________________________________________________________________________________________
a  Number of animals examined microscopically at site and number of animals with lesion                                             
b  Primary tumors: all tumors except metastatic tumors                                                                              
                                                             Page   7                                                               
NTP Experiment-Test: 05150-02  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 05/20/95  
Route: DOSED FEED                                                                                                 Time: 09:59:05  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         B6C3F1 MICE MALE                          0 PPM        50 PPM       250 PPM      500 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
DISPOSITION SUMMARY                                                                                                                 
  Animals Initially in Study                          70           70           70           70                                     
  Scheduled Sacrifice                                 20           20           20           20                                     
  Early Deaths                                                                                                                      
    Moribund Sacrifice                                 2            2            4            4                                     
    Natural Death                                      3            3            2            5                                     
  Survivors                                                                                                                         
    Terminal Sacrifice                                45           45           43           41                                     
    Moribund Sacrifice                                                           1                                                  
  Animals Examined Microscopically                    70           70           70           70                                     
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Intestine Large, Cecum                             (68)         (69)         (68)         (67)                                   
   Intestine Small, Duodenum                          (67)         (68)         (68)         (68)                                   
   Intestine Small, Jejunum                           (68)         (68)         (67)         (66)                                   
   Intestine Small, Ileum                             (66)         (68)         (67)         (65)                                   
      Sarcoma                                                       1 (1%)                                                          
   Liver                                              (70)         (70)         (70)         (70)                                   
      Hemangioma                                                                 1 (1%)                                             
      Hemangiosarcoma                                  3 (4%)       2 (3%)       1 (1%)                                             
      Hepatoblastoma                                                1 (1%)                    4 (6%)                                
      Hepatoblastoma, Multiple                                                   1 (1%)       1 (1%)                                
      Hepatocellular Carcinoma                         8 (11%)      8 (11%)     15 (21%)     11 (16%)                               
      Hepatocellular Carcinoma, Multiple               2 (3%)       1 (1%)       2 (3%)       1 (1%)                                
      Hepatocellular Adenoma                          15 (21%)      8 (11%)     12 (17%)     16 (23%)                               
      Hepatocellular Adenoma, Multiple                 5 (7%)      10 (14%)      6 (9%)      15 (21%)                               
      Histiocytic Sarcoma                                           1 (1%)                    1 (1%)                                
      Sarcoma                                                       1 (1%)                                                          
   Mesentery                                          (2)          (3)          (1)          (2)                                    
      Hepatoblastoma, Metastatic, Liver                                                       1 (50%)                               
      Sarcoma                                                       1 (33%)                                                         
   Pancreas                                           (70)         (69)         (69)         (70)                                   
      Hemangiosarcoma, Metastatic, Spleen                                                     1 (1%)                                
      Sarcoma                                                       1 (1%)                                                          
   Salivary Glands                                    (70)         (70)         (70)         (70)                                   
   Stomach, Forestomach                               (69)         (70)         (70)         (70)                                   
      Squamous Cell Papilloma                          1 (1%)       1 (1%)                                                          
   Stomach, Glandular                                 (68)         (69)         (70)         (67)                                   
      Sarcoma                                                       1 (1%)                                                          
   Tongue                                             (3)                       (1)          (2)                                    
      Squamous Cell Papilloma                          1 (33%)                                                                      
____________________________________________________________________________________________________________________________________
                                                             Page   8                                                               
NTP Experiment-Test: 05150-02  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 05/20/95  
Route: DOSED FEED                                                                                                 Time: 09:59:05  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         B6C3F1 MICE MALE                          0 PPM        50 PPM       250 PPM      500 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Heart                                              (70)         (70)         (70)         (70)                                   
      Adenocarcinoma, Metastatic, Prostate                          1 (1%)                                                          
      Hemangiosarcoma                                               1 (1%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Cortex                                     (69)         (69)         (70)         (70)                                   
      Adenoma                                          1 (1%)                    1 (1%)                                             
      Capsule, Adenoma                                 1 (1%)       2 (3%)                                                          
   Adrenal Medulla                                    (68)         (67)         (69)         (66)                                   
      Pheochromocytoma Benign                          1 (1%)                                                                       
   Islets, Pancreatic                                 (70)         (68)         (69)         (70)                                   
      Adenoma                                          1 (1%)       1 (1%)       1 (1%)       1 (1%)                                
   Pituitary Gland                                    (68)         (68)         (64)         (64)                                   
      Pars Intermedia, Adenoma                                                                1 (2%)                                
      Pars Intermedia, Carcinoma                                                 1 (2%)                                             
   Thyroid Gland                                      (70)         (69)         (69)         (70)                                   
      Follicular Cell, Adenoma                         1 (1%)       1 (1%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Epididymis                                         (70)         (70)         (70)         (70)                                   
   Prostate                                           (69)         (69)         (67)         (65)                                   
      Adenocarcinoma                                                1 (1%)                                                          
      Sarcoma                                                       1 (1%)                                                          
   Seminal Vesicle                                    (70)         (69)         (70)         (70)                                   
      Sarcoma                                                       2 (3%)                                                          
   Testes                                             (70)         (70)         (70)         (70)                                   
      Interstitial Cell, Adenoma                                                 2 (3%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Bone Marrow                                        (70)         (70)         (70)         (69)                                   
      Hemangiosarcoma                                               1 (1%)       1 (1%)       2 (3%)                                
      Histiocytic Sarcoma                                           1 (1%)                                                          
      Mast Cell Tumor NOS                                                                     1 (1%)                                
   Lymph Node                                         (3)          (5)          (1)          (2)                                    
                                                             Page   9                                                               
NTP Experiment-Test: 05150-02  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 05/20/95  
Route: DOSED FEED                                                                                                 Time: 09:59:05  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         B6C3F1 MICE MALE                          0 PPM        50 PPM       250 PPM      500 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
HEMATOPOIETIC SYSTEM - cont                                                                                                         
      Mediastinal, Histiocytic Sarcoma                              1 (20%)                                                         
      Mediastinal, Sarcoma                                          2 (40%)                                                         
      Pancreatic, Sarcoma                                           1 (20%)                                                         
   Lymph Node, Mandibular                             (66)         (65)         (67)         (66)                                   
   Lymph Node, Mesenteric                             (68)         (65)         (65)         (65)                                   
      Histiocytic Sarcoma                                           1 (2%)                                                          
      Sarcoma                                                       2 (3%)                                                          
   Spleen                                             (69)         (69)         (69)         (70)                                   
      Hemangiosarcoma                                  1 (1%)                    1 (1%)       3 (4%)                                
      Histiocytic Sarcoma                                           1 (1%)                                                          
      Mast Cell Tumor NOS                                                                     1 (1%)                                
      Sarcoma                                                       1 (1%)                                                          
   Thymus                                             (58)         (60)         (58)         (56)                                   
      Sarcoma                                                       1 (2%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Skin                                               (70)         (70)         (69)         (70)                                   
      Fibroma                                                                                 1 (1%)                                
      Hemangiosarcoma                                                                         1 (1%)                                
      Lipoma                                                                     1 (1%)                                             
      Sarcoma                                          2 (3%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (70)         (70)         (70)         (70)                                   
      Carcinoma, Metastatic, Pituitary Gland                                     1 (1%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Lung                                               (70)         (69)         (70)         (70)                                   
      Adenocarcinoma, Metastatic, Prostate                          1 (1%)                                                          
      Alveolar/Bronchiolar Adenoma                    13 (19%)      7 (10%)      5 (7%)       5 (7%)                                
      Alveolar/Bronchiolar Adenoma, Multiple           1 (1%)                    2 (3%)                                             
      Alveolar/Bronchiolar Carcinoma                   4 (6%)       5 (7%)       2 (3%)       1 (1%)                                
      Carcinoma, Metastatic, Harderian Gland           1 (1%)                                 1 (1%)                                
      Hepatoblastoma, Metastatic, Liver                                                       1 (1%)                                
      Hepatocellular Carcinoma, Metastatic, Liver      4 (6%)                    4 (6%)                                             
      Histiocytic Sarcoma                                           1 (1%)                    1 (1%)                                
                                                             Page  10                                                               
NTP Experiment-Test: 05150-02  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 05/20/95  
Route: DOSED FEED                                                                                                 Time: 09:59:05  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         B6C3F1 MICE MALE                          0 PPM        50 PPM       250 PPM      500 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
RESPIRATORY SYSTEM - cont                                                                                                           
      Sarcoma                                                       1 (1%)                                                          
      Sarcoma, Metastatic, Mesentery                                1 (1%)                                                          
   Nose                                               (70)         (70)         (70)         (70)                                   
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   Harderian Gland                                    (5)          (2)                       (2)                                    
      Adenoma                                          4 (80%)      1 (50%)                   1 (50%)                               
      Carcinoma                                        1 (20%)                                1 (50%)                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (70)         (70)         (70)         (70)                                   
      Histiocytic Sarcoma                                           1 (1%)                                                          
   Urinary Bladder                                    (68)         (68)         (68)         (67)                                   
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SYSTEMIC LESIONS                                                                                                                   
   Multiple Organs                                   *(70)        *(70)        *(70)        *(70)                                   
      Histiocytic Sarcoma                                           1 (1%)                    1 (1%)                                
      Lymphoma Malignant Lymphocytic                                1 (1%)                    1 (1%)                                
      Lymphoma Malignant Mixed                         3 (4%)       4 (6%)       3 (4%)       8 (11%)                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
     *   Number of animals with any tissue examined microscopically                                                                 
                                                             Page  11                                                               
NTP Experiment-Test: 05150-02  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 05/20/95  
Route: DOSED FEED                                                                                                 Time: 09:59:05  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         B6C3F1 MICE MALE                          0 PPM        50 PPM       250 PPM      500 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
TUMOR SUMMARY                                                                                                                       
                                                                                                                                    
   Total Animals with Primary Neoplasms (b)            43          36          35          46                                       
     Total Primary Neoplasms                           69          73          58          77                                       
                                                                                                                                    
   Total Animals with Benign Neoplasms                 33          24          25          35                                       
     Total Benign Neoplasms                            45          31          31          40                                       
                                                                                                                                    
   Total Animals with Malignant Neoplasms              19          24          22          25                                       
     Total Malignant Neoplasms                         24          42          27          35                                       
                                                                                                                                    
   Total Animals with Metastatic Neoplasms              5           2           5           4                                       
     Total Metastatic Neoplasm                          5           3           5           4                                       
                                                                                                                                    
   Total Animals with Malignant Neoplasms                                                                                           
   Uncertain Primary Site                                                                                                           
                                                                                                                                    
   Total Animals with Neoplasms Uncertain-                                                                                          
   Benign or Malignant                                                                      1                                       
     Total Uncertain Neoplasms                                                              2                                       
                                                                                                                                    
____________________________________________________________________________________________________________________________________
a  Number of animals examined microscopically at site and number of animals with lesion                                             
b  Primary tumors: all tumors except metastatic tumors                                                                              
                                                             Page  12                                                               
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