NTP Experiment-Test: 96013-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT18
Study Type: SUBCHRON 90-DAY                          WITH AVERAGE SEVERITY GRADES[b]                              Date: 10/27/04
Route: GAVAGE                                                     MELATONIN                                       Time: 08:03:55

                                                    FINAL #1 LONG EVANS RATS




       Facility:  Battelle Columbus Laboratory

       Chemical CAS #:  73-31-4

       Lock Date:  02/28/03

       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
b  Average severity grade (1-minimal;2-mild;3-moderate;4-marked)

                                                              Page   1


NTP Experiment-Test: 96013-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT18  
Study Type: SUBCHRON 90-DAY                          WITH AVERAGE SEVERITY GRADES[b]                              Date: 10/27/04    
Route: GAVAGE                                                     MELATONIN                                       Time: 08:03:55    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         LONG-EVANS RATS FEMALE                       0  UG/KG     5  UG/KG     50 UG/KG     5000         50,000       200,000      
                                                                                             UG/KG        UG/KG        UG/KG        
____________________________________________________________________________________________________________________________________
                                                                                                                                    
DISPOSITION SUMMARY                                                                                                                 
                                                                                                                                    
  Animals Initially In Study                          10           10           10           10           10           10           
  Early Deaths                                                                                                                      
    Natural Death                                                                1                                                  
  Survivors                                                                                                                         
    Terminal Sacrifice                                10           10            9           10           10           10           
                                                                                                                                    
  Animals Examined Microscopically                    10           10           10           10           10           10           
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Esophagus                                          (10)                                                             (10)         
      Inflammation, Chronic                                                                                             1 [2.0]     
   Liver                                              (10)                                                             (10)         
      Clear Cell Focus                                 1                                                                            
      Inflammation, Chronic                            5 [1.0]                                                          5 [1.0]     
   Pancreas                                           (10)                                                             (10)         
      Acinus, Atrophy                                                                                                   1 [1.0]     
   Tooth                                              (4)                                                              (4)          
      Pulp, Malformation                               4 [1.0]                                                          4 [1.0]     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Ovary                                              (10)         (10)         (10)         (10)         (10)         (10)         
      Angiectasis                                                   1 [3.0]      1 [3.0]                                            
      Cyst                                             2            4            4            4            6            4           
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
b  Average severity grade (1-minimal;2-mild;3-moderate;4-marked)                                                                    
                                                                                                                                    
                                                             Page    2                                                              
                                                                                                                                   
NTP Experiment-Test: 96013-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT18  
Study Type: SUBCHRON 90-DAY                          WITH AVERAGE SEVERITY GRADES[b]                              Date: 10/27/04    
Route: GAVAGE                                                     MELATONIN                                       Time: 08:03:55    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         LONG-EVANS RATS FEMALE                       0  UG/KG     5  UG/KG     50 UG/KG     5000         50,000       200,000      
                                                                                             UG/KG        UG/KG        UG/KG        
____________________________________________________________________________________________________________________________________
                                                                                                                                    
GENITAL SYSTEM - CONT                                                                                                               
      Mineralization                                                                                                    1 [1.0]     
   Uterus                                             (10)         (10)         (10)         (10)         (10)         (10)         
      Dilatation                                       2 [2.0]      5 [1.8]      3 [1.3]      5 [1.6]      8 [1.5]      8 [1.8]     
      Metaplasia, Squamous                                          1 [1.0]                                1 [1.0]                  
   Vagina                                                                       (1)                                                 
      Cyst                                                                       1                                                  
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Bone Marrow                                        (10)                      (1)                                    (10)         
      Myeloid Cell, Hyperplasia                                                  1 [4.0]                                            
   Lymph Node                                                                   (1)                                                 
      Lumbar, Hyperplasia, Plasma Cell                                           1 [3.0]                                            
   Lymph Node, Mandibular                             (10)         (1)                                                 (10)         
      Hyperplasia, Lymphoid                                         1 [1.0]                                                         
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (10)                                                             (10)         
      Cranial Nerve, Degeneration                      2 [2.0]                                                          1 [1.0]     
      Pineal Gland, Inflammation                       1 [1.0]                                                                      
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Lung                                               (10)                                                             (10)         
      Inflammation, Chronic                            3 [1.0]                                                                      
      Metaplasia, Osseous                              2 [1.0]                                                          1 [1.0]     
      Alveolar Epithelium, Hyperplasia                 1 [1.0]                                                                      
____________________________________________________________________________________________________________________________________
                                                                                                                                    
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
b  Average severity grade (1-minimal;2-mild;3-moderate;4-marked)                                                                    
                                                                                                                                    
                                                             Page    3                                                              
                                                                                                                                   
NTP Experiment-Test: 96013-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT18  
Study Type: SUBCHRON 90-DAY                          WITH AVERAGE SEVERITY GRADES[b]                              Date: 10/27/04    
Route: GAVAGE                                                     MELATONIN                                       Time: 08:03:55    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         LONG-EVANS RATS FEMALE                       0  UG/KG     5  UG/KG     50 UG/KG     5000         50,000       200,000      
                                                                                             UG/KG        UG/KG        UG/KG        
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   Eye                                                (10)         (10)         (9)          (10)         (10)         (10)         
      Cornea, Inflammation, Chronic                                                           1 [2.0]                               
      Iris, Synechia                                                                          1 [3.0]                               
      Retina, Dysplasia                                             1 [1.0]                                                         
   Harderian Gland                                    (10)         (10)         (9)          (10)         (10)         (10)         
      Pigmentation                                     3 [2.0]      4 [2.0]      1 [2.0]      4 [2.0]      8 [2.0]      6 [2.0]     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (10)                                                             (10)         
      Mineralization                                   6 [1.0]                                                          6 [1.0]     
      Nephropathy                                      5 [1.2]                                                          8 [1.0]     
      Renal Tubule, Hyperplasia                                                                                         1 [1.0]     
                                                                                                                                    
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
b  Average severity grade (1-minimal;2-mild;3-moderate;4-marked)                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page    4                                                              
                                                                                                                                   
NTP Experiment-Test: 96013-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT18  
Study Type: SUBCHRON 90-DAY                          WITH AVERAGE SEVERITY GRADES[b]                              Date: 10/27/04    
Route: GAVAGE                                                     MELATONIN                                       Time: 08:03:55    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         LONG-EVANS RATS MALE                         0  UG/KG     5  UG/KG     50 UG/KG     5000         50,000       200,000      
                                                                                             UG/KG        UG/KG        UG/KG        
____________________________________________________________________________________________________________________________________
                                                                                                                                    
DISPOSITION SUMMARY                                                                                                                 
                                                                                                                                    
  Animals Initially In Study                          10           10           10           10           10           10           
  Early Deaths                                                                                                                      
  Survivors                                                                                                                         
    Terminal Sacrifice                                10           10           10           10           10           10           
                                                                                                                                    
  Animals Examined Microscopically                    10           10           10           10           10           10           
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Liver                                              (10)                                                             (10)         
      Inflammation, Chronic                            5 [1.0]                                                          6 [1.0]     
      Vacuolization Cytoplasmic, Focal                                                                                  1 [1.0]     
   Pancreas                                           (10)                                                             (10)         
      Acinus, Atrophy                                  1 [1.0]                                                          1 [1.0]     
   Stomach, Glandular                                 (10)                                   (1)                       (10)         
      Hyperplasia, Focal                                                                      1 [2.0]                               
   Tooth                                              (6)                                                              (3)          
      Pulp, Malformation                               6 [1.0]                                                          3 [1.0]     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Heart                                              (10)                                                             (10)         
      Cardiomyopathy                                                                                                    2 [1.0]     
      Myocardium, Infiltration Cellular,                                                                                            
        Mononuclear Cell                               5 [1.0]                                                          1 [1.0]     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Epididymis                                         (10)                      (1)                                    (10)         
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
b  Average severity grade (1-minimal;2-mild;3-moderate;4-marked)                                                                    
                                                                                                                                    
                                                             Page    5                                                              
                                                                                                                                   
NTP Experiment-Test: 96013-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT18  
Study Type: SUBCHRON 90-DAY                          WITH AVERAGE SEVERITY GRADES[b]                              Date: 10/27/04    
Route: GAVAGE                                                     MELATONIN                                       Time: 08:03:55    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         LONG-EVANS RATS MALE                         0  UG/KG     5  UG/KG     50 UG/KG     5000         50,000       200,000      
                                                                                             UG/KG        UG/KG        UG/KG        
____________________________________________________________________________________________________________________________________
                                                                                                                                    
GENITAL SYSTEM - CONT                                                                                                               
      Atrophy                                                                    1 [4.0]                                            
   Preputial Gland                                    (10)                                                             (10)         
      Cyst                                             1                                                                            
      Inflammation, Granulomatous                                                                                       1 [1.0]     
   Prostate                                           (10)                                                             (10)         
      Inflammation, Chronic Active                                                                                      1 [2.0]     
   Testes                                             (10)                      (2)                                    (10)         
      Bilateral, Germinal Epithelium, Degeneration                               1 [4.0]                                            
      Germinal Epithelium, Degeneration                                          1 [4.0]                                1 [1.0]     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Lymph Node                                                                                                          (1)          
      Inguinal, Inflammation, Granulomatous                                                                             1 [1.0]     
   Lymph Node, Mandibular                             (10)                                                             (10)         
      Congestion                                                                                                        2 [2.0]     
      Hyperplasia, Lymphoid                                                                                             2 [2.0]     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (10)                                                             (10)         
      Cranial Nerve, Degeneration                      2 [2.5]                                                                      
      Cranial Nerve, Gliosis                           3 [1.0]                                                          1 [1.0]     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Lung                                               (10)                                                             (10)         
      Foreign Body                                                                                                      1           
      Inflammation, Chronic                            3 [1.0]                                                          2 [1.0]     
      Inflammation, Granulomatous                      1 [1.0]                                                                      
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
b  Average severity grade (1-minimal;2-mild;3-moderate;4-marked)                                                                    
                                                                                                                                    
                                                             Page    6                                                              
                                                                                                                                   
NTP Experiment-Test: 96013-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT18  
Study Type: SUBCHRON 90-DAY                          WITH AVERAGE SEVERITY GRADES[b]                              Date: 10/27/04    
Route: GAVAGE                                                     MELATONIN                                       Time: 08:03:55    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         LONG-EVANS RATS MALE                         0  UG/KG     5  UG/KG     50 UG/KG     5000         50,000       200,000      
                                                                                             UG/KG        UG/KG        UG/KG        
____________________________________________________________________________________________________________________________________
                                                                                                                                    
RESPIRATORY SYSTEM - CONT                                                                                                           
      Metaplasia, Osseous                              2 [1.0]                                                          1 [1.0]     
   Nose                                               (10)                                                             (10)         
      Inflammation, Chronic                                                                                             3 [1.0]     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   Harderian Gland                                    (10)         (10)         (10)         (8)          (10)         (10)         
      Infiltration Cellular, Lymphoid                               1 [2.0]                                                         
      Inflammation, Chronic                                         2 [1.5]                   2 [1.0]                               
      Pigmentation                                                  6 [2.0]      5 [2.0]      5 [2.0]      4 [2.0]      6 [2.0]     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (10)                                                             (10)         
      Mineralization                                   5 [1.2]                                                          5 [1.0]     
      Nephropathy                                      3 [1.0]                                                          5 [1.0]     
                                                                                                                                    
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
b  Average severity grade (1-minimal;2-mild;3-moderate;4-marked)                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                             Page    7                                                              
                                                                                                                                   
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