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TDMS Study 05180-06 Pathology Tables

NTP                                    STATISTICAL ANALYSIS OF NON-NEOPLASTIC LESIONS                          REPORT: PEIRPT10     
LAB: Battelle Northwest                                     GALLIUM ARSENIDE                                   DATE: 02/17/99       
EXPERIMENT: 05180 TEST: 06                                                                                     TIME: 08:20:28       
TEST TYPE:  CHRONIC                             CAGES FROM 0000 TO LAST CAGE                                   PAGE:       1        
CONT: NO1-ES-25335                              ROUTE: RESPIRATORY EXPOSURE WHOLE BODY                         NTP C#: 62033B       
PATHOLOGIST: GRUMBEIN, S.                                                                                      CAS: 1303-00-0000    
------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                    
                                                        2 YEAR CHRONIC RATS                                                         
                                                                                                                                    

               REASONS FOR REMOVAL:    ALL                                                                                          
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
                                                                                                                                    
               REMOVAL DATE RANGE:     ALL                                                                                          
                                                                                                                                    
               TREATMENT GROUPS:       INCLUDE ALL                                                                                  
NTP                                    STATISTICAL ANALYSIS OF NON-NEOPLASTIC LESIONS                          REPORT: PEIRPT10   
LAB: Battelle Northwest                                     GALLIUM ARSENIDE                                   DATE: 02/17/99     
EXPERIMENT: 05180 TEST: 06                                                                                     TIME: 08:20:28     
TEST TYPE:  CHRONIC                             CAGES FROM 0000 TO LAST CAGE                                                      
CONT: NO1-ES-25335                              ROUTE: RESPIRATORY EXPOSURE WHOLE BODY                         NTP C#: 62033B     
PATHOLOGIST: GRUMBEIN, S.                                                                                      CAS: 1303-00-0000  



SUMMARY OF STATISTICALLY SIGNIFICANT (P<=.05) RESULTS
IN THE ANALYSIS OF                 GALLIUM ARSENIDE
===============================================================

Male Rats
------------
Organ                                 Morphology
-----                                 ----------
Adrenal Medulla                        Hyperplasia
Epididymis                             Granuloma Sperm
Eye                                    Degeneration
Larynx                                 Hyperplasia
                                       Inflammation Chronic
                                       Metaplasia
Larynx: Epiglottis                     Hyperplasia
                                       Inflammation Chronic
                                       Metaplasia
Liver                                  Angiectasis
                                       Clear Cell Focus
Lung                                   Hyperplasia Atypical
                                       Inflammation Chronic
                                       Proteinosis
Lung: Alveolar Epithelium              Hyperplasia
                                       Metaplasia
Nose: Olfactory Epithelium             Degeneration Hyaline
Spleen                                 Necrosis
Stomach, Glandular                     Necrosis
===============================================================
Female Rats
------------
Organ                                  Morphology
-----                                  ----------
Larynx                                 Metaplasia
Larynx: Epiglottis                     Hyperplasia
Liver                                  Mixed Cell Focus
Liver: Bile Duct                       Hyperplasia
Liver: Centrilobular                   Necrosis
Lung                                   Hyperplasia Atypical
                                       Inflammation Chronic
                                       Proteinosis
Lung: Alveolar Epithelium              Metaplasia
Mesentery: Fat                         Necrosis
Nose                                   Inflammation
Nose: Olfactory Epithelium             Atrophy
Pituitary Gland: Pars Distalis         Angiectasis
                                       Hyperplasia
Thyroid Gland: C-Cell                  Hyperplasia
===============================================================
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 1
                     Statistical Analysis of Non-neoplastic Lesions in        Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Adrenal Cortex                                                                                                                   |
|     Degeneration Cystic                                                                                                         |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/49 (0%)    0/49 (0%)    1/49 (2%)    0/50 (0%)   |4/50 (8%)    2/50 (4%)    1/50 (2%)    0/49 (0%)    |
|POLY-3 ADJUSTED (b)|     0.0%         0.0%         2.7%         0.0%        |10.1%        5.2%         2.7%         0.0%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    0/13 (0%)   |3/19 (16%)   1/17 (6%)    1/21 (5%)    0/11 (0%)    |
|FIRST INCIDENCE    |     ---          ---          722          ---         |649          714          734 (T)      ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.750N     (e)          P=0.513      (e)         |P=0.184N     P=0.382N     P=0.163N     P=0.134N     |
|POLY 3             |     P=0.743N     (e)          P=0.506      (e)         |P=0.122N     P=0.352N     P=0.198N     P=0.081N     |
|POLY 1.5           |     P=0.741N     (e)          P=0.503      (e)         |P=0.116N     P=0.346N     P=0.192N     P=0.074N     |
|POLY 6             |     P=0.745N     (e)          P=0.510      (e)         |P=0.131N     P=0.359N     P=0.201N     P=0.091N     |
|LOGISTIC REGRESSION|     P=0.752N     (e)          P=0.515      (e)         |P=0.142N     P=0.354N     P=0.196N     P=0.096N     |
|COCH-ARM / FISHERS |     P=0.739N     (e)          P=0.500      (e)         |P=0.107N     P=0.339N     P=0.181N     P=0.061N     |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Adrenal Cortex                                                                                                                   |
|     Hyperplasia                                                                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     24/49 (49%)  24/49 (49%)  23/49 (47%)  23/50 (46%) |27/50 (54%)  23/50 (46%)  25/50 (50%)  22/49 (45%)  |
|POLY-3 ADJUSTED (b)|     58.8%        62.5%        54.8%        56.0%       |62.5%        54.8%        63.1%        59.2%        |
|TERMINAL (d)       |     11/13 (85%)  10/13 (77%)  8/15 (53%)   6/13 (46%)  |14/19 (74%)  11/17 (65%)  17/21 (81%)  7/11 (64%)   |
|FIRST INCIDENCE    |     506          548          394          422         |506          559          604          556          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.514      P=0.498      P=0.351N     P=0.562     |P=0.175      P=0.414N     P=0.388N     P=0.312      |
|POLY 3             |     P=0.430N     P=0.453      P=0.437N     P=0.484N    |P=0.549N     P=0.299N     P=0.573      P=0.469N     |
|POLY 1.5           |     P=0.438N     P=0.496      P=0.467N     P=0.483N    |P=0.461N     P=0.287N     P=0.548N     P=0.376N     |
|POLY 6             |     P=0.396N     P=0.416      P=0.381N     P=0.453N    |P=0.512      P=0.304N     P=0.518      P=0.566N     |
|LOGISTIC REGRESSION|     P=0.512N     P=0.456      P=0.470N     P=0.528N    |P=0.544      P=0.319N     P=0.567N     P=0.510N     |
|COCH-ARM / FISHERS |     P=0.441N     P=0.580N     P=0.500N     P=0.462N    |P=0.319N     P=0.274N     P=0.421N     P=0.241N     |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 2
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Adrenal Cortex                                                                                                                   |
|     Hypertrophy                                                                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     1/49 (2%)    3/49 (6%)    3/49 (6%)    2/50 (4%)   |10/50 (20%)  11/50 (22%)  9/50 (18%)   11/49 (22%)  |
|POLY-3 ADJUSTED (b)|     2.8%         8.8%         7.9%         5.7%        |24.7%        27.0%        23.5%        31.2%        |
|TERMINAL (d)       |     0/13 (0%)    2/13 (15%)   1/15 (7%)    1/13 (8%)   |6/19 (32%)   2/17 (12%)   7/21 (33%)   5/11 (46%)   |
|FIRST INCIDENCE    |     685          699          443          614         |582          548          534          631          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.608N     P=0.312      P=0.331      P=0.488     |P=0.136      P=0.441      P=0.463N     P=0.173      |
|POLY 3             |     P=0.606N     P=0.282      P=0.323      P=0.490     |P=0.313      P=0.505      P=0.558N     P=0.350      |
|POLY 1.5           |     P=0.595N     P=0.290      P=0.315      P=0.496     |P=0.360      P=0.502      P=0.541N     P=0.396      |
|POLY 6             |     P=0.617N     P=0.273      P=0.334      P=0.485     |P=0.263      P=0.521      P=0.573N     P=0.305      |
|LOGISTIC REGRESSION|     P=0.596N     P=0.272      P=0.296      P=0.487     |P=0.308      P=0.478      P=0.562N     P=0.290      |
|COCH-ARM / FISHERS |     P=0.580N     P=0.309      P=0.309      P=0.508     |P=0.445      P=0.500      P=0.500N     P=0.479      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Adrenal Cortex                                                                                                                   |
|     Necrosis                                                                                                                    |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     1/49 (2%)    0/49 (0%)    4/49 (8%)    3/50 (6%)   |0/50 (0%)    4/50 (8%)    2/50 (4%)    2/49 (4%)    |
|POLY-3 ADJUSTED (b)|     2.8%         0.0%         10.5%        8.3%        |0.0%         10.3%        5.3%         5.8%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    1/15 (7%)    0/13 (0%)   |0/19 (0%)    1/17 (6%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     645          ---          513          520         |---          631          448          554          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.243      P=0.529N     P=0.205      P=0.264     |P=0.527      P=0.056      P=0.240      P=0.208      |
|POLY 3             |     P=0.279      P=0.513N     P=0.192      P=0.302     |P=0.589      P=0.057      P=0.228      P=0.209      |
|POLY 1.5           |     P=0.277      P=0.509N     P=0.186      P=0.305     |P=0.605      P=0.058      P=0.230      P=0.217      |
|POLY 6             |     P=0.287      P=0.519N     P=0.202      P=0.302     |P=0.571      P=0.056      P=0.228      P=0.201      |
|LOGISTIC REGRESSION|     P=0.285      P=0.501N     P=0.175      P=0.341     |P=0.635      P=0.058      P=0.264      P=0.246      |
|COCH-ARM / FISHERS |     P=0.274      P=0.500N     P=0.181      P=0.316     |P=0.636      P=0.059      P=0.247      P=0.242      |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 3
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Adrenal Cortex                                                                                                                   |
|     Vacuolization Cytoplasmic                                                                                                   |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     2/49 (4%)    5/49 (10%)   2/49 (4%)    1/50 (2%)   |2/50 (4%)    4/50 (8%)    4/50 (8%)    3/49 (6%)    |
|POLY-3 ADJUSTED (b)|     5.5%         14.1%        5.3%         2.9%        |5.1%         10.2%        10.7%        8.7%         |
|TERMINAL (d)       |     0/13 (0%)    1/13 (8%)    1/15 (7%)    1/13 (8%)   |2/19 (11%)   2/17 (12%)   3/21 (14%)   1/11 (9%)    |
|FIRST INCIDENCE    |     621          393          562          733 (T)     |734 (T)      422          646          631          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.224N     P=0.184      P=0.672N     P=0.521N    |P=0.452      P=0.305      P=0.370      P=0.330      |
|POLY 3             |     P=0.221N     P=0.199      P=0.685N     P=0.517N    |P=0.589      P=0.333      P=0.312      P=0.439      |
|POLY 1.5           |     P=0.211N     P=0.205      P=0.689N     P=0.507N    |P=0.611      P=0.336      P=0.319      P=0.457      |
|POLY 6             |     P=0.235N     P=0.193      P=0.679N     P=0.529N    |P=0.565      P=0.332      P=0.311      P=0.420      |
|LOGISTIC REGRESSION|     P=0.199N     P=0.213      P=0.695N     P=0.518N    |P=0.593      P=0.331      P=0.306      P=0.401      |
|COCH-ARM / FISHERS |     P=0.196N     P=0.218      P=0.691N     P=0.492N    |P=0.590N     P=0.339      P=0.339      P=0.490      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Adrenal Medulla                                                                                                                  |
|     Hyperplasia                                                                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     22/50 (44%)  26/49 (53%)  23/49 (47%)  33/50 (66%) |16/50 (32%)  11/49 (22%)  16/50 (32%)  12/49 (24%)  |
|POLY-3 ADJUSTED (b)|     52.9%        63.2%        55.9%        75.2%       |38.3%        28.0%        40.2%        32.4%        |
|TERMINAL (d)       |     6/13 (46%)   7/13 (54%)   8/15 (53%)   9/13 (69%)  |7/19 (37%)   3/16 (19%)   7/21 (33%)   3/11 (27%)   |
|FIRST INCIDENCE    |     506          532          513          422         |581          613          448          418          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.030 *    P=0.241      P=0.501N     P=0.044 *   |P=0.389      P=0.286N     P=0.567      P=0.513      |
|POLY 3             |     P=0.019 *    P=0.221      P=0.479      P=0.017 *   |P=0.455N     P=0.222N     P=0.521      P=0.375N     |
|POLY 1.5           |     P=0.018 *    P=0.216      P=0.470      P=0.016 *   |P=0.421N     P=0.212N     P=0.536      P=0.339N     |
|POLY 6             |     P=0.026 *    P=0.249      P=0.500      P=0.027 *   |P=0.493N     P=0.227N     P=0.520      P=0.410N     |
|LOGISTIC REGRESSION|     P=0.014 *    P=0.194      P=0.505      P=0.015 *   |P=0.466N     P=0.224N     P=0.514      P=0.371N     |
|COCH-ARM / FISHERS |     P=0.021 *    P=0.242      P=0.463      P=0.022 *   |P=0.355N     P=0.200N     P=0.585N     P=0.272N     |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 4
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Blood Vessel: Aorta                                                                                                              |
|     Mineralization                                                                                                              |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     3/3 (100%)   4/4 (100%)   4/6 (67%)    6/6 (100%)  |0/0 (0%)     0/0 (0%)     0/0 (0%)     1/1 (100%)   |
|POLY-3 ADJUSTED (b)|     100.0%       100.0%       75.3%        100.0%      |0.0%         0.0%         0.0%         100.0%       |
|TERMINAL (d)       |     0/0 (0%)     1/1 (100%)   1/1 (100%)   1/1 (100%)  |0/0 (0%)     0/0 (0%)     0/0 (0%)     0/0 (0%)     |
|FIRST INCIDENCE    |     590          660          660          605         |---          ---          ---          712          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.223      (e)          P=0.624N     (e)         |(e)          (e)          (e)          (e)          |
|POLY 3             |     P=0.622      (e)          P=0.523N     (e)         |(e)          (e)          (e)          (e)          |
|POLY 1.5           |     P=0.542      (e)          P=0.453N     (e)         |(e)          (e)          (e)          (e)          |
|POLY 6             |     P=0.773      (e)          P=0.680N     (e)         |(e)          (e)          (e)          (e)          |
|LOGISTIC REGRESSION|     P=0.442      (e)          P=0.265N     (e)         |(e)          (e)          (e)          (e)          |
|COCH-ARM / FISHERS |     P=0.467      (e)          P=0.417N     (e)         |(e)          (e)          (e)          (e)          |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Bone                                                                                                                             |
|     Fibrous Osteodystrophy                                                                                                      |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     8/50 (16%)   9/50 (18%)   10/50 (20%)  11/50 (22%) |1/50 (2%)    0/50 (0%)    1/50 (2%)    2/50 (4%)    |
|POLY-3 ADJUSTED (b)|     20.9%        24.7%        25.2%        29.8%       |2.5%         0.0%         2.7%         5.8%         |
|TERMINAL (d)       |     2/13 (15%)   2/13 (15%)   3/15 (20%)   4/13 (31%)  |0/19 (0%)    0/17 (0%)    1/21 (5%)    0/11 (0%)    |
|FIRST INCIDENCE    |     534          306          394          519         |703          ---          734 (T)      677          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.275      P=0.434      P=0.474      P=0.273     |P=0.164      P=0.508N     P=0.759N     P=0.399      |
|POLY 3             |     P=0.277      P=0.453      P=0.426      P=0.260     |P=0.228      P=0.507N     P=0.747      P=0.454      |
|POLY 1.5           |     P=0.295      P=0.467      P=0.413      P=0.277     |P=0.238      P=0.504N     P=0.751      P=0.471      |
|POLY 6             |     P=0.259      P=0.448      P=0.448      P=0.247     |P=0.216      P=0.510N     P=0.745      P=0.435      |
|LOGISTIC REGRESSION|     P=0.298      P=0.469      P=0.406      P=0.261     |P=0.200      P=0.507N     P=0.750      P=0.437      |
|COCH-ARM / FISHERS |     P=0.319      P=0.500      P=0.398      P=0.306     |P=0.258      P=0.500N     P=0.753N     P=0.500      |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 5
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Bone                                                                                                                             |
|     Hyperostosis                                                                                                                |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/50 (0%)    0/50 (0%)    0/50 (0%)    1/50 (2%)   |7/50 (14%)   3/50 (6%)    7/50 (14%)   9/50 (18%)   |
|POLY-3 ADJUSTED (b)|     0.0%         0.0%         0.0%         2.9%        |16.9%        7.6%         17.7%        24.9%        |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    0/13 (0%)   |1/19 (5%)    0/17 (0%)    1/21 (5%)    1/11 (9%)    |
|FIRST INCIDENCE    |     ---          ---          ---          700         |506          590          448          478          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.276      (e)          (e)          P=0.532     |P=0.064      P=0.192N     P=0.566      P=0.206      |
|POLY 3             |     P=0.256      (e)          (e)          P=0.491     |P=0.094      P=0.177N     P=0.580      P=0.277      |
|POLY 1.5           |     P=0.257      (e)          (e)          P=0.494     |P=0.112      P=0.168N     P=0.587      P=0.319      |
|POLY 6             |     P=0.255      (e)          (e)          P=0.488     |P=0.076      P=0.187N     P=0.580      P=0.233      |
|LOGISTIC REGRESSION|     P=0.247      (e)          (e)          P=0.487     |P=0.142      P=0.154N     P=0.593N     P=0.339      |
|COCH-ARM / FISHERS |     P=0.257      (e)          (e)          P=0.500     |P=0.150      P=0.159N     P=0.613N     P=0.393      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Clitoral Gland                                                                                                                   |
|     Hyperplasia                                                                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |                                                        |2/50 (4%)    4/48 (8%)    3/47 (6%)    2/48 (4%)    |
|POLY-3 ADJUSTED (b)|                                                        |5.0%         10.5%        8.6%         6.1%         |
|TERMINAL (d)       |                                                        |0/19 (0%)    1/16 (6%)    2/20 (10%)   0/10 (0%)    |
|FIRST INCIDENCE    |                                                        |642          613          668          674          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |                                                        |P=0.581N     P=0.303      P=0.492      P=0.594      |
|POLY 3             |                                                        |P=0.502N     P=0.313      P=0.441      P=0.625      |
|POLY 1.5           |                                                        |P=0.475N     P=0.316      P=0.450      P=0.645      |
|POLY 6             |                                                        |P=0.535N     P=0.310      P=0.437      P=0.601      |
|LOGISTIC REGRESSION|                                                        |P=0.500N     P=0.314      P=0.443      P=0.635      |
|COCH-ARM / FISHERS |                                                        |P=0.429N     P=0.319      P=0.470      P=0.676      |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 6
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Clitoral Gland                                                                                                                   |
|     Inflammation Chronic                                                                                                        |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |                                                        |2/50 (4%)    2/48 (4%)    1/47 (2%)    2/48 (4%)    |
|POLY-3 ADJUSTED (b)|                                                        |5.0%         5.3%         2.9%         6.0%         |
|TERMINAL (d)       |                                                        |0/19 (0%)    1/16 (6%)    1/20 (5%)    0/10 (0%)    |
|FIRST INCIDENCE    |                                                        |506          631          734 (T)      631          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |                                                        |P=0.482      P=0.667      P=0.516N     P=0.615      |
|POLY 3             |                                                        |P=0.540      P=0.669      P=0.550N     P=0.622      |
|POLY 1.5           |                                                        |P=0.560      P=0.674      P=0.542N     P=0.643      |
|POLY 6             |                                                        |P=0.517      P=0.664      P=0.557N     P=0.597      |
|LOGISTIC REGRESSION|                                                        |P=0.575      P=0.682      P=0.517N     P=0.693      |
|COCH-ARM / FISHERS |                                                        |P=0.594      P=0.676      P=0.523N     P=0.676      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Epididymis                                                                                                                       |
|     Granuloma Sperm                                                                                                             |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/50 (0%)    0/50 (0%)    0/50 (0%)    3/50 (6%)   |                                                    |
|POLY-3 ADJUSTED (b)|     0.0%         0.0%         0.0%         8.3%        |                                                    |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    0/13 (0%)   |                                                    |
|FIRST INCIDENCE    |     ---          ---          ---          523         |                                                    |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.007 **   (e)          (e)          P=0.107     |                                                    |
|POLY 3             |     P=0.008 **   (e)          (e)          P=0.115     |                                                    |
|POLY 1.5           |     P=0.008 **   (e)          (e)          P=0.116     |                                                    |
|POLY 6             |     P=0.008 **   (e)          (e)          P=0.116     |                                                    |
|LOGISTIC REGRESSION|     P=0.009 **   (e)          (e)          P=0.138     |                                                    |
|COCH-ARM / FISHERS |     P=0.009 **   (e)          (e)          P=0.121     |                                                    |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 7
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Eye                                                                                                                              |
|     Cataract                                                                                                                    |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     4/4 (100%)   1/2 (50%)    0/1 (0%)     1/1 (100%)  |1/1 (100%)   4/5 (80%)    1/6 (17%)    1/1 (100%)   |
|POLY-3 ADJUSTED (b)|     100.0%       93.2%        0.0%         100.0%      |100.0%       80.0%        18.2%        100.0%       |
|TERMINAL (d)       |     0/0 (0%)     0/0 (0%)     0/1 (0%)     1/1 (100%)  |1/1 (100%)   1/2 (50%)    0/3 (0%)     0/0 (0%)     |
|FIRST INCIDENCE    |     647          534          ---          733 (T)     |734 (T)      422          674          674          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.350N     P=0.232N     P=0.067N     (e)         |P=0.707      P=0.240      P=0.641N     (e)          |
|POLY 3             |     P=1.000      P=1.000N     P=1.000      (e)         |P=0.707      P=0.793N     P=0.301N     (e)          |
|POLY 1.5           |     P=0.998      P=0.990N     P=1.000      (e)         |P=0.701      P=0.793N     P=0.293N     (e)          |
|POLY 6             |     P=1.000      P=1.000N     P=1.000      (e)         |P=0.716      P=0.793N     P=0.316N     (e)          |
|LOGISTIC REGRESSION|     P=0.926      (e)          (e)          (e)         |P=0.711      (e)          P=0.273N     (e)          |
|COCH-ARM / FISHERS |     P=0.758      P=0.333N     P=0.200N     (e)         |P=0.667      P=0.833N     P=0.286N     (e)          |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Eye                                                                                                                              |
|     Degeneration                                                                                                                |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/4 (0%)     0/2 (0%)     1/1 (100%)   0/1 (0%)    |0/1 (0%)     1/5 (20%)    4/6 (67%)    0/1 (0%)     |
|POLY-3 ADJUSTED (b)|     0.0%         0.0%         100.0%       0.0%        |0.0%         24.5%        72.1%        0.0%         |
|TERMINAL (d)       |     0/0 (0%)     0/0 (0%)     1/1 (100%)   0/1 (0%)    |0/1 (0%)     1/2 (50%)    3/3 (100%)   0/0 (0%)     |
|FIRST INCIDENCE    |     ---          ---          733 (T)      ---         |---          734 (T)      660          ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.500N     (e)          P=1.000      (e)         |P=0.820N     P=0.638      P=0.123      (e)          |
|POLY 3             |     P=1.000N     (e)          P<0.001 **   (e)         |P=0.744N     P=0.778      P=0.394      (e)          |
|POLY 1.5           |     P=1.000N     (e)          P<0.001 **   (e)         |P=0.712N     P=0.784      P=0.418      (e)          |
|POLY 6             |     P=1.000N     (e)          P<0.001 **   (e)         |P=0.819N     P=0.772      P=0.341      (e)          |
|LOGISTIC REGRESSION|     (e)          (e)          P=1.000      (e)         |P=0.841N     P=0.638      P=0.295      (e)          |
|COCH-ARM / FISHERS |     P=0.910N     (e)          P=0.200      (e)         |P=0.692N     P=0.833      P=0.429      (e)          |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 8
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Eye: Retina                                                                                                                      |
|     Atrophy                                                                                                                     |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     4/4 (100%)   1/2 (50%)    0/1 (0%)     1/1 (100%)  |1/1 (100%)   4/5 (80%)    1/6 (17%)    1/1 (100%)   |
|POLY-3 ADJUSTED (b)|     100.0%       93.2%        0.0%         100.0%      |100.0%       80.0%        18.2%        100.0%       |
|TERMINAL (d)       |     0/0 (0%)     0/0 (0%)     0/1 (0%)     1/1 (100%)  |1/1 (100%)   1/2 (50%)    0/3 (0%)     0/0 (0%)     |
|FIRST INCIDENCE    |     647          534          ---          733 (T)     |734 (T)      422          674          674          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.350N     P=0.232N     P=0.067N     (e)         |P=0.707      P=0.240      P=0.641N     (e)          |
|POLY 3             |     P=1.000      P=1.000N     P=1.000N     (e)         |P=0.707      P=0.793N     P=0.301N     (e)          |
|POLY 1.5           |     P=0.998      P=0.990N     P=1.000N     (e)         |P=0.701      P=0.793N     P=0.293N     (e)          |
|POLY 6             |     P=1.000      P=1.000N     P=1.000N     (e)         |P=0.716      P=0.793N     P=0.316N     (e)          |
|LOGISTIC REGRESSION|     P=0.926      (e)          (e)          (e)         |P=0.711      (e)          P=0.273N     (e)          |
|COCH-ARM / FISHERS |     P=0.758      P=0.333N     P=0.200N     (e)         |P=0.667      P=0.833N     P=0.286N     (e)          |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Heart                                                                                                                            |
|     Cardiomyopathy                                                                                                              |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     44/50 (88%)  37/50 (74%)  41/50 (82%)  40/50 (80%) |34/50 (68%)  37/50 (74%)  29/50 (58%)  31/50 (62%)  |
|POLY-3 ADJUSTED (b)|     93.0%        86.3%        88.1%        88.1%       |76.2%        86.2%        70.5%        78.0%        |
|TERMINAL (d)       |     12/13 (92%)  13/13 (100%) 13/15 (87%)  13/13 (100%)|16/19 (84%)  17/17 (100%) 18/21 (86%)  11/11 (100%) |
|FIRST INCIDENCE    |     506          548          450          422         |497          559          310          418          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.454      P=0.333N     P=0.243N     P=0.460N    |P=0.069      P=0.233      P=0.221N     P=0.103      |
|POLY 3             |     P=0.495N     P=0.201N     P=0.300N     P=0.292N    |P=0.548N     P=0.147      P=0.351N     P=0.528      |
|POLY 1.5           |     P=0.459N     P=0.131N     P=0.288N     P=0.237N    |P=0.433N     P=0.222      P=0.285N     P=0.548N     |
|POLY 6             |     P=0.626N     P=0.316N     P=0.321N     P=0.450N    |P=0.501      P=0.086      P=0.440N     P=0.364      |
|LOGISTIC REGRESSION|     P=0.573N     P=0.151N     P=0.257N     P=0.291N    |P=0.502      P=0.183      P=0.311N     P=0.481      |
|COCH-ARM / FISHERS |     P=0.494N     P=0.062N     P=0.288N     P=0.207N    |P=0.281N     P=0.330      P=0.204N     P=0.338N     |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 9
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Heart: Artery                                                                                                                    |
|     Mineralization                                                                                                              |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     5/50 (10%)   6/50 (12%)   5/50 (10%)   7/50 (14%)  |0/50 (0%)    0/50 (0%)    0/50 (0%)    1/50 (2%)    |
|POLY-3 ADJUSTED (b)|     13.3%        16.8%        13.1%        19.5%       |0.0%         0.0%         0.0%         2.9%         |
|TERMINAL (d)       |     0/13 (0%)    1/13 (8%)    1/15 (7%)    1/13 (8%)   |0/19 (0%)    0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     590          306          660          605         |---          ---          ---          712          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.317      P=0.438      P=0.585N     P=0.347     |P=0.181      (e)          (e)          P=0.415      |
|POLY 3             |     P=0.318      P=0.462      P=0.626N     P=0.341     |P=0.239      (e)          (e)          P=0.473      |
|POLY 1.5           |     P=0.332      P=0.474      P=0.628N     P=0.355     |P=0.246      (e)          (e)          P=0.483      |
|POLY 6             |     P=0.305      P=0.452      P=0.622N     P=0.329     |P=0.232      (e)          (e)          P=0.462      |
|LOGISTIC REGRESSION|     P=0.328      P=0.487      P=0.612N     P=0.338     |P=0.218      (e)          (e)          P=0.450      |
|COCH-ARM / FISHERS |     P=0.350      P=0.500      P=0.630N     P=0.380     |P=0.257      (e)          (e)          P=0.500      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Heart: Atrium                                                                                                                    |
|     Thrombosis                                                                                                                  |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     4/50 (8%)    1/50 (2%)    3/50 (6%)    2/50 (4%)   |2/50 (4%)    3/50 (6%)    0/50 (0%)    0/50 (0%)    |
|POLY-3 ADJUSTED (b)|     10.6%        2.9%         7.9%         5.6%        |5.0%         7.7%         0.0%         0.0%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    0/13 (0%)   |0/19 (0%)    0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     599          600          566          604         |607          628          ---          ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.527N     P=0.231N     P=0.480N     P=0.390N    |P=0.201N     P=0.473      P=0.263N     P=0.279N     |
|POLY 3             |     P=0.504N     P=0.205N     P=0.496N     P=0.366N    |P=0.182N     P=0.488      P=0.253N     P=0.272N     |
|POLY 1.5           |     P=0.499N     P=0.196N     P=0.498N     P=0.355N    |P=0.174N     P=0.493      P=0.248N     P=0.258N     |
|POLY 6             |     P=0.511N     P=0.216N     P=0.496N     P=0.380N    |P=0.195N     P=0.484      P=0.258N     P=0.290N     |
|LOGISTIC REGRESSION|     P=0.497N     P=0.175N     P=0.499N     P=0.336N    |P=0.165N     P=0.502      P=0.233N     P=0.235N     |
|COCH-ARM / FISHERS |     P=0.495N     P=0.181N     P=0.500N     P=0.339N    |P=0.163N     P=0.500      P=0.247N     P=0.247N     |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 10
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Intestine Large, Cecum                                                                                                           |
|     Mineralization                                                                                                              |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/46 (0%)    3/43 (7%)    0/48 (0%)    0/49 (0%)   |0/50 (0%)    0/49 (0%)    0/48 (0%)    0/49 (0%)    |
|POLY-3 ADJUSTED (b)|     0.0%         9.2%         0.0%         0.0%        |0.0%         0.0%         0.0%         0.0%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    0/13 (0%)   |0/19 (0%)    0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     ---          655          ---          ---         |---          ---          ---          ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.337N     P=0.101      (e)          (e)         |(e)          (e)          (e)          (e)          |
|POLY 3             |     P=0.307N     P=0.107      (e)          (e)         |(e)          (e)          (e)          (e)          |
|POLY 1.5           |     P=0.301N     P=0.107      (e)          (e)         |(e)          (e)          (e)          (e)          |
|POLY 6             |     P=0.314N     P=0.109      (e)          (e)         |(e)          (e)          (e)          (e)          |
|LOGISTIC REGRESSION|     P=0.308N     P=0.108      (e)          (e)         |(e)          (e)          (e)          (e)          |
|COCH-ARM / FISHERS |     P=0.295N     P=0.109      (e)          (e)         |(e)          (e)          (e)          (e)          |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Intestine Small, Duodenum                                                                                                        |
|     Necrosis                                                                                                                    |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/48 (0%)    0/48 (0%)    2/49 (4%)    0/50 (0%)   |0/50 (0%)    1/48 (2%)    0/48 (0%)    2/49 (4%)    |
|POLY-3 ADJUSTED (b)|     0.0%         0.0%         5.4%         0.0%        |0.0%         2.7%         0.0%         5.8%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    0/13 (0%)   |0/19 (0%)    0/16 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     ---          ---          680          ---         |---          585          ---          554          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.587N     (e)          P=0.246      (e)         |P=0.106      P=0.486      (e)          P=0.166      |
|POLY 3             |     P=0.558N     (e)          P=0.249      (e)         |P=0.140      P=0.489      (e)          P=0.208      |
|POLY 1.5           |     P=0.556N     (e)          P=0.246      (e)         |P=0.146      P=0.490      (e)          P=0.216      |
|POLY 6             |     P=0.561N     (e)          P=0.256      (e)         |P=0.133      P=0.489      (e)          P=0.199      |
|LOGISTIC REGRESSION|     P=0.570N     (e)          P=0.252      (e)         |P=0.171      P=0.495      (e)          P=0.233      |
|COCH-ARM / FISHERS |     P=0.555N     (e)          P=0.253      (e)         |P=0.158      P=0.490      (e)          P=0.242      |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 11
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Islets, Pancreatic                                                                                                               |
|     Hyperplasia                                                                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     1/48 (2%)    2/49 (4%)    2/50 (4%)    4/50 (8%)   |0/50 (0%)    0/50 (0%)    0/50 (0%)    1/49 (2%)    |
|POLY-3 ADJUSTED (b)|     2.8%         5.8%         5.3%         11.3%       |0.0%         0.0%         0.0%         2.9%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    1/15 (7%)    1/13 (8%)   |0/19 (0%)    0/17 (0%)    0/21 (0%)    1/11 (9%)    |
|FIRST INCIDENCE    |     621          647          590          642         |---          ---          ---          734 (T)      |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.132      P=0.480      P=0.531      P=0.159     |P=0.159      (e)          (e)          P=0.391      |
|POLY 3             |     P=0.144      P=0.486      P=0.520      P=0.172     |P=0.236      (e)          (e)          P=0.470      |
|POLY 1.5           |     P=0.150      P=0.493      P=0.517      P=0.179     |P=0.242      (e)          (e)          P=0.480      |
|POLY 6             |     P=0.137      P=0.479      P=0.524      P=0.164     |P=0.229      (e)          (e)          P=0.459      |
|LOGISTIC REGRESSION|     P=0.144      P=0.498      P=0.513      P=0.172     |(e)          (e)          (e)          P=0.391      |
|COCH-ARM / FISHERS |     P=0.158      P=0.508      P=0.515      P=0.194     |P=0.253      (e)          (e)          P=0.495      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Kidney                                                                                                                           |
|     Cyst                                                                                                                        |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     3/49 (6%)    3/50 (6%)    1/50 (2%)    1/50 (2%)   |0/50 (0%)    1/50 (2%)    2/50 (4%)    0/49 (0%)    |
|POLY-3 ADJUSTED (b)|     8.1%         8.6%         2.6%         2.9%        |0.0%         2.6%         5.3%         0.0%         |
|TERMINAL (d)       |     1/13 (8%)    0/13 (0%)    0/15 (0%)    0/13 (0%)   |0/19 (0%)    0/17 (0%)    1/21 (5%)    0/11 (0%)    |
|FIRST INCIDENCE    |     590          621          660          713         |---          590          630          ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.331N     P=0.610      P=0.275N     P=0.337N    |P=0.469N     P=0.490      P=0.251      (e)          |
|POLY 3             |     P=0.310N     P=0.642      P=0.295N     P=0.323N    |P=0.450N     P=0.497      P=0.226      (e)          |
|POLY 1.5           |     P=0.300N     P=0.650      P=0.296N     P=0.313N    |P=0.436N     P=0.498      P=0.228      (e)          |
|POLY 6             |     P=0.323N     P=0.638      P=0.292N     P=0.336N    |P=0.467N     P=0.496      P=0.225      (e)          |
|LOGISTIC REGRESSION|     P=0.293N     P=0.663      P=0.297N     P=0.314N    |P=0.412N     P=0.503      P=0.228      (e)          |
|COCH-ARM / FISHERS |     P=0.288N     P=0.651N     P=0.301N     P=0.301N    |P=0.411N     P=0.500      P=0.247      (e)          |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 12
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Kidney                                                                                                                           |
|     Infarct                                                                                                                     |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/49 (0%)    2/50 (4%)    1/50 (2%)    2/50 (4%)   |0/50 (0%)    3/50 (6%)    1/50 (2%)    1/49 (2%)    |
|POLY-3 ADJUSTED (b)|     0.0%         5.8%         2.6%         5.6%        |0.0%         7.6%         2.7%         2.9%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    0/13 (0%)   |0/19 (0%)    0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     ---          574          601          547         |---          497          678          702          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.379      P=0.230      P=0.520      P=0.250     |P=0.667N     P=0.111      P=0.465      P=0.445      |
|POLY 3             |     P=0.369      P=0.228      P=0.510      P=0.233     |P=0.628N     P=0.117      P=0.489      P=0.471      |
|POLY 1.5           |     P=0.375      P=0.231      P=0.507      P=0.236     |P=0.614N     P=0.118      P=0.492      P=0.480      |
|POLY 6             |     P=0.365      P=0.226      P=0.516      P=0.231     |P=0.645N     P=0.118      P=0.489      P=0.461      |
|LOGISTIC REGRESSION|     P=0.387      P=0.239      P=0.499      P=0.250     |P=0.586N     P=0.123      P=0.493      P=0.459      |
|COCH-ARM / FISHERS |     P=0.383      P=0.253      P=0.505      P=0.253     |P=0.591N     P=0.121      P=0.500      P=0.495      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Kidney                                                                                                                           |
|     Mineralization                                                                                                              |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     5/49 (10%)   4/50 (8%)    5/50 (10%)   4/50 (8%)   |0/50 (0%)    0/50 (0%)    0/50 (0%)    1/49 (2%)    |
|POLY-3 ADJUSTED (b)|     13.3%        11.6%        13.0%        11.2%       |0.0%         0.0%         0.0%         2.9%         |
|TERMINAL (d)       |     0/13 (0%)    1/13 (8%)    1/15 (7%)    0/13 (0%)   |0/19 (0%)    0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     590          660          654          605         |---          ---          ---          712          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.553N     P=0.549N     P=0.579N     P=0.566N    |P=0.181      (e)          (e)          P=0.415      |
|POLY 3             |     P=0.516N     P=0.551N     P=0.617N     P=0.530N    |P=0.237      (e)          (e)          P=0.471      |
|POLY 1.5           |     P=0.505N     P=0.528N     P=0.617N     P=0.513N    |P=0.242      (e)          (e)          P=0.480      |
|POLY 6             |     P=0.531N     P=0.578N     P=0.616N     P=0.551N    |P=0.230      (e)          (e)          P=0.460      |
|LOGISTIC REGRESSION|     P=0.518N     P=0.533N     P=0.612N     P=0.506N    |P=0.217      (e)          (e)          P=0.450      |
|COCH-ARM / FISHERS |     P=0.493N     P=0.487N     P=0.617N     P=0.487N    |P=0.253      (e)          (e)          P=0.495      |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 13
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Kidney                                                                                                                           |
|     Nephropathy                                                                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     48/49 (98%)  49/50 (98%)  50/50 (100%) 50/50 (100%)|48/50 (96%)  47/50 (94%)  47/50 (94%)  45/49 (92%)  |
|POLY-3 ADJUSTED (b)|     99.2%        100.0%       100.0%       100.0%      |99.7%        98.9%        99.2%        97.6%        |
|TERMINAL (d)       |     13/13 (100%) 13/13 (100%) 15/15 (100%) 13/13 (100%)|19/19 (100%) 17/17 (100%) 21/21 (100%) 11/11 (100%) |
|FIRST INCIDENCE    |     338          306          394          310         |497          497          310          215          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.339      P=0.350      P=0.453N     P=0.334     |P=0.051      P=0.439      P=0.514N     P=0.084      |
|POLY 3             |     P=0.981      P=0.948      P=0.941      P=0.941     |P=0.343N     P=0.950N     P=0.997N     P=0.493N     |
|POLY 1.5           |     P=0.811      P=0.791      P=0.723      P=0.723     |P=0.274N     P=0.638N     P=0.788N     P=0.328N     |
|POLY 6             |     P=1.000      P=1.000      P=1.000      P=1.000     |P=0.958N     P=1.000N     P=1.000N     P=0.991N     |
|LOGISTIC REGRESSION|     P=0.495      P=0.500      P=0.511      P=0.447     |P=0.601      (e)          P=0.646      P=0.659N     |
|COCH-ARM / FISHERS |     P=0.434      P=0.747      P=0.495      P=0.495     |P=0.336N     P=0.500N     P=0.500N     P=0.329N     |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Kidney: Renal Tubule                                                                                                             |
|     Hyperplasia                                                                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     2/49 (4%)    1/50 (2%)    4/50 (8%)    2/50 (4%)   |2/50 (4%)    1/50 (2%)    1/50 (2%)    2/49 (4%)    |
|POLY-3 ADJUSTED (b)|     5.5%         2.9%         10.6%        5.7%        |5.0%         2.6%         2.7%         5.9%         |
|TERMINAL (d)       |     1/13 (8%)    0/13 (0%)    3/15 (20%)   1/13 (8%)   |0/19 (0%)    0/17 (0%)    1/21 (5%)    2/11 (18%)   |
|FIRST INCIDENCE    |     671          647          702          618         |642          700          734 (T)      734 (T)      |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.645      P=0.533N     P=0.400      P=0.669     |P=0.354      P=0.497N     P=0.521N     P=0.555      |
|POLY 3             |     P=0.621N     P=0.519N     P=0.352      P=0.685     |P=0.449      P=0.514N     P=0.525N     P=0.635      |
|POLY 1.5           |     P=0.616N     P=0.511N     P=0.350      P=0.691     |P=0.466      P=0.507N     P=0.517N     P=0.655      |
|POLY 6             |     P=0.628N     P=0.525N     P=0.356      P=0.680     |P=0.428      P=0.521N     P=0.532N     P=0.609      |
|LOGISTIC REGRESSION|     P=0.642N     P=0.523N     P=0.368      P=0.678     |P=0.426      P=0.504N     P=0.517N     P=0.626      |
|COCH-ARM / FISHERS |     P=0.612N     P=0.492N     P=0.349      P=0.684N    |P=0.493      P=0.500N     P=0.500N     P=0.684      |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 14
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Larynx                                                                                                                           |
|     Hyperplasia                                                                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     3/50 (6%)    8/50 (16%)   4/49 (8%)    11/50 (22%) |3/50 (6%)    1/50 (2%)    0/50 (0%)    1/49 (2%)    |
|POLY-3 ADJUSTED (b)|     8.1%         22.4%        10.6%        29.2%       |7.5%         2.6%         0.0%         2.9%         |
|TERMINAL (d)       |     1/13 (8%)    2/13 (15%)   1/15 (7%)    2/13 (15%)  |2/19 (11%)   0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     684          590          654          523         |506          613          ---          631          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.026 *    P=0.093      P=0.540      P=0.024 *   |P=0.629N     P=0.334N     P=0.114N     P=0.426N     |
|POLY 3             |     P=0.025 *    P=0.082      P=0.511      P=0.017 *   |P=0.562N     P=0.317N     P=0.132N     P=0.362N     |
|POLY 1.5           |     P=0.025 *    P=0.086      P=0.500      P=0.018 *   |P=0.553N     P=0.312N     P=0.128N     P=0.344N     |
|POLY 6             |     P=0.026 *    P=0.083      P=0.530      P=0.019 *   |P=0.574N     P=0.321N     P=0.134N     P=0.382N     |
|LOGISTIC REGRESSION|     P=0.023 *    P=0.075      P=0.527      P=0.017 *   |P=0.534N     P=0.301N     P=0.120N     P=0.315N     |
|COCH-ARM / FISHERS |     P=0.029 *    P=0.100      P=0.489      P=0.020 *   |P=0.539N     P=0.309N     P=0.121N     P=0.316N     |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Larynx                                                                                                                           |
|     Inflammation Chronic                                                                                                        |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     4/50 (8%)    3/50 (6%)    4/49 (8%)    12/50 (24%) |4/50 (8%)    5/50 (10%)   3/50 (6%)    3/49 (6%)    |
|POLY-3 ADJUSTED (b)|     10.7%        8.7%         10.6%        31.5%       |10.0%        12.9%        8.0%         8.6%         |
|TERMINAL (d)       |     1/13 (8%)    1/13 (8%)    1/15 (7%)    2/13 (15%)  |2/19 (11%)   3/17 (18%)   2/21 (10%)   1/11 (9%)    |
|FIRST INCIDENCE    |     590          621          654          523         |589          687          646          631          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.002 **   P=0.536N     P=0.598N     P=0.031 *   |P=0.617      P=0.469      P=0.491N     P=0.631      |
|POLY 3             |     P<0.001 **   P=0.543N     P=0.642N     P=0.022 *   |P=0.482N     P=0.476      P=0.537N     P=0.580N     |
|POLY 1.5           |     P<0.001 **   P=0.529N     P=0.641      P=0.023 *   |P=0.460N     P=0.487      P=0.526N     P=0.555N     |
|POLY 6             |     P<0.001 **   P=0.555N     P=0.632N     P=0.025 *   |P=0.508N     P=0.465      P=0.546N     P=0.607N     |
|LOGISTIC REGRESSION|     P<0.001 **   P=0.543N     P=0.631N     P=0.024 *   |P=0.502N     P=0.477      P=0.530N     P=0.561N     |
|COCH-ARM / FISHERS |     P=0.002 **   P=0.500N     P=0.631      P=0.027 *   |P=0.421N     P=0.500      P=0.500N     P=0.511N     |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 15
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Larynx                                                                                                                           |
|     Metaplasia                                                                                                                  |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     1/50 (2%)    2/50 (4%)    2/49 (4%)    10/50 (20%) |10/50 (20%)  5/50 (10%)   7/50 (14%)   11/49 (22%)  |
|POLY-3 ADJUSTED (b)|     2.7%         5.8%         5.4%         26.6%       |24.5%        12.9%        17.8%        30.0%        |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    1/15 (7%)    2/13 (15%)  |6/19 (32%)   3/17 (18%)   2/21 (10%)   2/11 (18%)   |
|FIRST INCIDENCE    |     684          621          671          523         |497          660          547          476          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P<0.001 **   P=0.493      P=0.525      P=0.006 **  |P=0.038 *    P=0.177N     P=0.296N     P=0.215      |
|POLY 3             |     P<0.001 **   P=0.478      P=0.504      P=0.003 **  |P=0.110      P=0.149N     P=0.324N     P=0.385      |
|POLY 1.5           |     P<0.001 **   P=0.484      P=0.499      P=0.004 **  |P=0.121      P=0.141N     P=0.322N     P=0.413      |
|POLY 6             |     P<0.001 **   P=0.476      P=0.514      P=0.004 **  |P=0.104      P=0.157N     P=0.312N     P=0.369      |
|LOGISTIC REGRESSION|     P<0.001 **   P=0.479      P=0.514      P=0.005 **  |P=0.108      P=0.144N     P=0.319N     P=0.390      |
|COCH-ARM / FISHERS |     P<0.001 **   P=0.500      P=0.492      P=0.004 **  |P=0.150      P=0.131N     P=0.298N     P=0.479      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Larynx                                                                                                                           |
|     Mineralization                                                                                                              |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     1/50 (2%)    0/50 (0%)    3/49 (6%)    1/50 (2%)   |0/50 (0%)    0/50 (0%)    0/50 (0%)    0/49 (0%)    |
|POLY-3 ADJUSTED (b)|     2.7%         0.0%         7.9%         2.9%        |0.0%         0.0%         0.0%         0.0%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    0/13 (0%)   |0/19 (0%)    0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     720          ---          654          715         |---          ---          ---          ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.689      P=0.541N     P=0.339      P=0.738     |(e)          (e)          (e)          (e)          |
|POLY 3             |     P=0.654N     P=0.515N     P=0.315      P=0.751     |(e)          (e)          (e)          (e)          |
|POLY 1.5           |     P=0.651N     P=0.510N     P=0.306      P=0.754     |(e)          (e)          (e)          (e)          |
|POLY 6             |     P=0.657N     P=0.518N     P=0.331      P=0.748     |(e)          (e)          (e)          (e)          |
|LOGISTIC REGRESSION|     P=0.667N     P=0.517N     P=0.307      P=0.752     |(e)          (e)          (e)          (e)          |
|COCH-ARM / FISHERS |     P=0.650N     P=0.500N     P=0.301      P=0.753N    |(e)          (e)          (e)          (e)          |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 16
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Larynx: Epiglottis                                                                                                               |
|     Hyperplasia                                                                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/50 (0%)    6/50 (12%)   4/49 (8%)    5/50 (10%)  |4/50 (8%)    2/50 (4%)    0/50 (0%)    3/49 (6%)    |
|POLY-3 ADJUSTED (b)|     0.0%         17.1%        10.6%        13.9%       |9.7%         5.2%         0.0%         8.7%         |
|TERMINAL (d)       |     0/13 (0%)    2/13 (15%)   1/15 (7%)    1/13 (8%)   |1/19 (5%)    1/17 (6%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     ---          621          654          605         |497          688          ---          631          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.256      P=0.019 *    P=0.080      P=0.029 *   |P=0.361      P=0.355N     P=0.074N     P=0.624N     |
|POLY 3             |     P=0.278      P=0.012 *    P=0.062      P=0.027 *   |P=0.428      P=0.366N     P=0.073N     P=0.592N     |
|POLY 1.5           |     P=0.283      P=0.013 *    P=0.060      P=0.028 *   |P=0.441      P=0.354N     P=0.069N     P=0.563N     |
|POLY 6             |     P=0.280      P=0.011 *    P=0.066      P=0.027 *   |P=0.413      P=0.380N     P=0.076N     P=0.623N     |
|LOGISTIC REGRESSION|     P=0.270      P=0.013 *    P=0.066      P=0.030 *   |P=0.463      P=0.330N     P=0.049N*    P=0.490N     |
|COCH-ARM / FISHERS |     P=0.297      P=0.013 *    P=0.056      P=0.028 *   |P=0.466      P=0.339N     P=0.059N     P=0.511N     |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Larynx: Epiglottis                                                                                                               |
|     Inflammation Chronic                                                                                                        |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/50 (0%)    1/50 (2%)    2/49 (4%)    4/50 (8%)   |4/50 (8%)    1/50 (2%)    1/50 (2%)    0/49 (0%)    |
|POLY-3 ADJUSTED (b)|     0.0%         2.9%         5.3%         11.2%       |10.0%        2.6%         2.7%         0.0%         |
|TERMINAL (d)       |     0/13 (0%)    1/13 (8%)    0/15 (0%)    2/13 (15%)  |2/19 (11%)   1/17 (6%)    1/21 (5%)    0/11 (0%)    |
|FIRST INCIDENCE    |     ---          733 (T)      654          605         |589          734 (T)      734 (T)      ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.037 *    P=0.500      P=0.260      P=0.058     |P=0.212N     P=0.206N     P=0.177N     P=0.121N     |
|POLY 3             |     P=0.045 *    P=0.486      P=0.242      P=0.055     |P=0.156N     P=0.192N     P=0.201N     P=0.083N     |
|POLY 1.5           |     P=0.046 *    P=0.490      P=0.237      P=0.057     |P=0.149N     P=0.186N     P=0.194N     P=0.075N     |
|POLY 6             |     P=0.045 *    P=0.482      P=0.251      P=0.054     |P=0.165N     P=0.199N     P=0.207N     P=0.094N     |
|LOGISTIC REGRESSION|     P=0.042 *    P=0.500      P=0.235      P=0.057     |P=0.166N     P=0.188N     P=0.196N     P=0.079N     |
|COCH-ARM / FISHERS |     P=0.048 *    P=0.500      P=0.242      P=0.059     |P=0.141N     P=0.181N     P=0.181N     P=0.061N     |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 17
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Larynx: Epiglottis                                                                                                               |
|     Metaplasia                                                                                                                  |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/50 (0%)    0/50 (0%)    0/49 (0%)    3/50 (6%)   |4/50 (8%)    6/50 (12%)   1/50 (2%)    3/49 (6%)    |
|POLY-3 ADJUSTED (b)|     0.0%         0.0%         0.0%         8.4%        |10.0%        15.6%        2.7%         8.6%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    1/13 (8%)   |2/19 (11%)   5/17 (29%)   1/21 (5%)    0/11 (0%)    |
|FIRST INCIDENCE    |     ---          ---          ---          602         |589          660          734 (T)      631          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.008 **   (e)          (e)          P=0.118     |P=0.597      P=0.301      P=0.167N     P=0.638      |
|POLY 3             |     P=0.008 **   (e)          (e)          P=0.112     |P=0.487N     P=0.345      P=0.199N     P=0.575N     |
|POLY 1.5           |     P=0.008 **   (e)          (e)          P=0.114     |P=0.470N     P=0.356      P=0.193N     P=0.553N     |
|POLY 6             |     P=0.008 **   (e)          (e)          P=0.112     |P=0.504N     P=0.334      P=0.203N     P=0.596N     |
|LOGISTIC REGRESSION|     P=0.009 **   (e)          (e)          P=0.119     |P=0.531N     P=0.341      P=0.198N     P=0.562N     |
|COCH-ARM / FISHERS |     P=0.009 **   (e)          (e)          P=0.121     |P=0.441N     P=0.370      P=0.181N     P=0.511N     |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Liver                                                                                                                            |
|     Angiectasis                                                                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/50 (0%)    2/50 (4%)    0/50 (0%)    5/50 (10%)  |2/50 (4%)    2/50 (4%)    5/50 (10%)   3/50 (6%)    |
|POLY-3 ADJUSTED (b)|     0.0%         5.9%         0.0%         13.8%       |5.0%         5.2%         13.2%        8.6%         |
|TERMINAL (d)       |     0/13 (0%)    2/13 (15%)   0/15 (0%)    2/13 (15%)  |1/19 (5%)    0/17 (0%)    3/21 (14%)   1/11 (9%)    |
|FIRST INCIDENCE    |     ---          733 (T)      ---          523         |677          660          630          677          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.006 **   P=0.235      (e)          P=0.033 *   |P=0.383      P=0.667      P=0.220      P=0.347      |
|POLY 3             |     P=0.006 **   P=0.220      (e)          P=0.028 *   |P=0.497      P=0.686      P=0.194      P=0.440      |
|POLY 1.5           |     P=0.007 **   P=0.226      (e)          P=0.029 *   |P=0.525      P=0.689      P=0.200      P=0.462      |
|POLY 6             |     P=0.006 **   P=0.216      (e)          P=0.028 *   |P=0.464      P=0.684      P=0.192      P=0.414      |
|LOGISTIC REGRESSION|     P=0.007 **   P=0.235      (e)          P=0.033 *   |P=0.482      P=0.684      P=0.190      P=0.403      |
|COCH-ARM / FISHERS |     P=0.008 **   P=0.247      (e)          P=0.028 *   |P=0.573      P=0.691N     P=0.218      P=0.500      |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 18
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Liver                                                                                                                            |
|     Basophilic Focus                                                                                                            |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     21/50 (42%)  23/50 (46%)  21/50 (42%)  15/50 (30%) |38/50 (76%)  36/50 (72%)  38/50 (76%)  34/50 (68%)  |
|POLY-3 ADJUSTED (b)|     52.1%        60.5%        51.5%        41.6%       |82.4%        81.8%        85.8%        82.0%        |
|TERMINAL (d)       |     10/13 (77%)  10/13 (77%)  10/15 (67%)  9/13 (69%)  |17/19 (90%)  15/17 (88%)  20/21 (95%)  10/11 (91%)  |
|FIRST INCIDENCE    |     534          548          562          602         |497          422          339          422          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.103N     P=0.353      P=0.427N     P=0.170N    |P=0.091      P=0.529      P=0.545N     P=0.143      |
|POLY 3             |     P=0.102N     P=0.287      P=0.567N     P=0.232N    |P=0.531N     P=0.584N     P=0.437      P=0.598N     |
|POLY 1.5           |     P=0.080N     P=0.326      P=0.576N     P=0.191N    |P=0.408N     P=0.492N     P=0.490      P=0.448N     |
|POLY 6             |     P=0.154N     P=0.262      P=0.540N     P=0.301N    |P=0.537      P=0.560      P=0.385      P=0.498      |
|LOGISTIC REGRESSION|     P=0.075N     P=0.262      P=0.529N     P=0.195N    |P=0.507N     P=0.481N     P=0.438      P=0.547N     |
|COCH-ARM / FISHERS |     P=0.064N     P=0.420      P=0.580N     P=0.149N    |P=0.234N     P=0.410N     P=0.592N     P=0.252N     |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Liver                                                                                                                            |
|     Clear Cell Focus                                                                                                            |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     6/50 (12%)   3/50 (6%)    6/50 (12%)   9/50 (18%)  |5/50 (10%)   7/50 (14%)   8/50 (16%)   2/50 (4%)    |
|POLY-3 ADJUSTED (b)|     16.4%        8.8%         16.0%        25.4%       |12.6%        17.7%        20.7%        5.7%         |
|TERMINAL (d)       |     6/13 (46%)   3/13 (23%)   6/15 (40%)   8/13 (62%)  |4/19 (21%)   5/17 (29%)   4/21 (19%)   1/11 (9%)    |
|FIRST INCIDENCE    |     733 (T)      733 (T)      733 (T)      540         |699          478          534          534          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.044 *    P=0.209N     P=0.521N     P=0.231     |P=0.192N     P=0.313      P=0.299      P=0.426N     |
|POLY 3             |     P=0.083      P=0.273N     P=0.608N     P=0.252     |P=0.099N     P=0.376      P=0.256      P=0.266N     |
|POLY 1.5           |     P=0.089      P=0.265N     P=0.614N     P=0.266     |P=0.086N     P=0.378      P=0.258      P=0.248N     |
|POLY 6             |     P=0.075      P=0.277N     P=0.595N     P=0.239     |P=0.118N     P=0.376      P=0.265      P=0.289N     |
|LOGISTIC REGRESSION|     P=0.058      P=0.209N     P=0.521N     P=0.223     |P=0.089N     P=0.356      P=0.236      P=0.296N     |
|COCH-ARM / FISHERS |     P=0.095      P=0.243N     P=0.620N     P=0.288     |P=0.067N     P=0.380      P=0.277      P=0.218N     |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 19
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Liver                                                                                                                            |
|     Degeneration Cystic                                                                                                         |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     9/50 (18%)   9/50 (18%)   10/50 (20%)  10/50 (20%) |0/50 (0%)    0/50 (0%)    0/50 (0%)    1/50 (2%)    |
|POLY-3 ADJUSTED (b)|     23.1%        25.4%        25.9%        26.9%       |0.0%         0.0%         0.0%         2.9%         |
|TERMINAL (d)       |     3/13 (23%)   4/13 (31%)   5/15 (33%)   3/13 (23%)  |0/19 (0%)    0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     566          590          604          523         |---          ---          ---          709          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.442      P=0.539      P=0.589      P=0.457     |P=0.193      (e)          (e)          P=0.428      |
|POLY 3             |     P=0.467      P=0.517      P=0.490      P=0.451     |P=0.239      (e)          (e)          P=0.473      |
|POLY 1.5           |     P=0.475      P=0.546      P=0.494      P=0.469     |P=0.246      (e)          (e)          P=0.483      |
|POLY 6             |     P=0.463      P=0.485      P=0.483      P=0.435     |P=0.232      (e)          (e)          P=0.462      |
|LOGISTIC REGRESSION|     P=0.443      P=0.541      P=0.526      P=0.472     |P=0.221      (e)          (e)          P=0.453      |
|COCH-ARM / FISHERS |     P=0.484      P=0.602N     P=0.500      P=0.500     |P=0.257      (e)          (e)          P=0.500      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Liver                                                                                                                            |
|     Eosinophilic Focus                                                                                                          |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     6/50 (12%)   4/50 (8%)    5/50 (10%)   4/50 (8%)   |2/50 (4%)    3/50 (6%)    3/50 (6%)    1/50 (2%)    |
|POLY-3 ADJUSTED (b)|     15.9%        11.3%        13.3%        11.1%       |5.1%         7.7%         8.0%         2.9%         |
|TERMINAL (d)       |     2/13 (15%)   0/13 (0%)    3/15 (20%)   1/13 (8%)   |2/19 (11%)   2/17 (12%)   2/21 (10%)   1/11 (9%)    |
|FIRST INCIDENCE    |     645          590          702          547         |734 (T)      585          646          734 (T)      |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.480N     P=0.445N     P=0.433N     P=0.433N    |P=0.469N     P=0.452      P=0.532      P=0.690N     |
|POLY 3             |     P=0.447N     P=0.409N     P=0.501N     P=0.395N    |P=0.334N     P=0.492      P=0.477      P=0.548N     |
|POLY 1.5           |     P=0.441N     P=0.399N     P=0.500N     P=0.386N    |P=0.313N     P=0.496      P=0.482      P=0.530N     |
|POLY 6             |     P=0.454N     P=0.416N     P=0.504N     P=0.404N    |P=0.361N     P=0.491      P=0.477      P=0.569N     |
|LOGISTIC REGRESSION|     P=0.461N     P=0.409N     P=0.459N     P=0.394N    |P=0.354N     P=0.482      P=0.470      P=0.690N     |
|COCH-ARM / FISHERS |     P=0.435N     P=0.370N     P=0.500N     P=0.370N    |P=0.280N     P=0.500      P=0.500      P=0.500N     |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 20
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Liver                                                                                                                            |
|     Fatty Change                                                                                                                |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     5/50 (10%)   8/50 (16%)   8/50 (16%)   7/50 (14%)  |12/50 (24%)  19/50 (38%)  11/50 (22%)  12/50 (24%)  |
|POLY-3 ADJUSTED (b)|     12.9%        21.7%        19.9%        18.8%       |28.3%        43.7%        25.9%        30.6%        |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    0/13 (0%)   |1/19 (5%)    2/17 (12%)   0/21 (0%)    1/11 (9%)    |
|FIRST INCIDENCE    |     544          350          443          539         |588          497          339          418          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.505      P=0.246      P=0.328      P=0.334     |P=0.537      P=0.111      P=0.556N     P=0.363      |
|POLY 3             |     P=0.536      P=0.235      P=0.296      P=0.348     |P=0.430N     P=0.098      P=0.496N     P=0.505      |
|POLY 1.5           |     P=0.547      P=0.248      P=0.287      P=0.359     |P=0.389N     P=0.097      P=0.502N     P=0.535      |
|POLY 6             |     P=0.527      P=0.227      P=0.312      P=0.342     |P=0.480N     P=0.105      P=0.490N     P=0.470      |
|LOGISTIC REGRESSION|     P=0.580      P=0.319      P=0.259      P=0.417     |P=0.250N     P=0.100      P=0.426N     P=0.560N     |
|COCH-ARM / FISHERS |     P=0.566      P=0.277      P=0.277      P=0.380     |P=0.318N     P=0.097      P=0.500N     P=0.592N     |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Liver                                                                                                                            |
|     Hepatodiaphragmatic Nodule                                                                                                  |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     1/50 (2%)    2/50 (4%)    3/50 (6%)    2/50 (4%)   |3/50 (6%)    3/50 (6%)    3/50 (6%)    4/50 (8%)    |
|POLY-3 ADJUSTED (b)|     2.7%         5.8%         7.9%         5.7%        |7.5%         7.7%         8.0%         11.4%        |
|TERMINAL (d)       |     1/13 (8%)    1/13 (8%)    1/15 (7%)    2/13 (15%)  |1/19 (5%)    2/17 (12%)   2/21 (10%)   1/11 (9%)    |
|FIRST INCIDENCE    |     733 (T)      625          601          733 (T)     |582          422          639          677          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.599      P=0.484      P=0.342      P=0.500     |P=0.247      P=0.629      P=0.659      P=0.352      |
|POLY 3             |     P=0.602      P=0.479      P=0.319      P=0.482     |P=0.356      P=0.651      P=0.632      P=0.425      |
|POLY 1.5           |     P=0.610      P=0.484      P=0.312      P=0.489     |P=0.381      P=0.657      P=0.641      P=0.452      |
|POLY 6             |     P=0.593      P=0.477      P=0.331      P=0.476     |P=0.329      P=0.644      P=0.626      P=0.394      |
|LOGISTIC REGRESSION|     P=0.599      P=0.469      P=0.317      P=0.500     |P=0.381      P=0.659N     P=0.643      P=0.434      |
|COCH-ARM / FISHERS |     P=0.618      P=0.500      P=0.309      P=0.500     |P=0.426      P=0.661N     P=0.661N     P=0.500      |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 21
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Liver                                                                                                                            |
|     Inflammation Granulomatous                                                                                                  |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     1/50 (2%)    0/50 (0%)    0/50 (0%)    0/50 (0%)   |3/50 (6%)    1/50 (2%)    0/50 (0%)    1/50 (2%)    |
|POLY-3 ADJUSTED (b)|     2.7%         0.0%         0.0%         0.0%        |7.5%         2.6%         0.0%         2.9%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    0/13 (0%)   |1/19 (5%)    0/17 (0%)    0/21 (0%)    1/11 (9%)    |
|FIRST INCIDENCE    |     647          ---          ---          ---         |621          687          ---          734 (T)      |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.701N     P=0.522N     P=0.487N     P=0.546N    |P=0.642N     P=0.324N     P=0.130N     P=0.444N     |
|POLY 3             |     P=0.661N     P=0.516N     P=0.497N     P=0.512N    |P=0.558N     P=0.320N     P=0.132N     P=0.362N     |
|POLY 1.5           |     P=0.660N     P=0.511N     P=0.498N     P=0.507N    |P=0.547N     P=0.313N     P=0.128N     P=0.339N     |
|POLY 6             |     P=0.663N     P=0.521N     P=0.495N     P=0.517N    |P=0.574N     P=0.327N     P=0.136N     P=0.391N     |
|LOGISTIC REGRESSION|     P=0.661N     P=0.504N     P=0.501N     P=0.501N    |P=0.571N     P=0.308N     P=0.124N     P=0.350N     |
|COCH-ARM / FISHERS |     P=0.660N     P=0.500N     P=0.500N     P=0.500N    |P=0.531N     P=0.309N     P=0.121N     P=0.309N     |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Liver                                                                                                                            |
|     Mixed Cell Focus                                                                                                            |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     1/50 (2%)    0/50 (0%)    0/50 (0%)    0/50 (0%)   |10/50 (20%)  9/50 (18%)   6/50 (12%)   2/50 (4%)    |
|POLY-3 ADJUSTED (b)|     2.7%         0.0%         0.0%         0.0%        |24.1%        22.8%        15.6%        5.8%         |
|TERMINAL (d)       |     1/13 (8%)    0/13 (0%)    0/15 (0%)    0/13 (0%)   |4/19 (21%)   3/17 (18%)   3/21 (14%)   1/11 (9%)    |
|FIRST INCIDENCE    |     733 (T)      ---          ---          ---         |590          548          534          704          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.668N     P=0.500N     P=0.471N     P=0.500N    |P=0.066N     P=0.548N     P=0.218N     P=0.065N     |
|POLY 3             |     P=0.662N     P=0.514N     P=0.495N     P=0.510N    |P=0.028N*    P=0.550N     P=0.251N     P=0.029N*    |
|POLY 1.5           |     P=0.660N     P=0.510N     P=0.498N     P=0.506N    |P=0.022N*    P=0.527N     P=0.237N     P=0.021N*    |
|POLY 6             |     P=0.666N     P=0.518N     P=0.491N     P=0.513N    |P=0.040N*    P=0.579N     P=0.267N     P=0.042N*    |
|LOGISTIC REGRESSION|     P=0.668N     (e)          (e)          (e)         |P=0.024N*    P=0.521N     P=0.226N     P=0.025N*    |
|COCH-ARM / FISHERS |     P=0.660N     P=0.500N     P=0.500N     P=0.500N    |P=0.016N*    P=0.500N     P=0.207N     P=0.014N*    |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 22
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Liver                                                                                                                            |
|     Necrosis                                                                                                                    |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     2/50 (4%)    0/50 (0%)    4/50 (8%)    1/50 (2%)   |1/50 (2%)    1/50 (2%)    4/50 (8%)    2/50 (4%)    |
|POLY-3 ADJUSTED (b)|     5.3%         0.0%         10.3%        2.8%        |2.5%         2.6%         10.2%        5.7%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    0/13 (0%)   |0/19 (0%)    0/17 (0%)    1/21 (5%)    1/11 (9%)    |
|FIRST INCIDENCE    |     590          ---          590          621         |660          606          310          554          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.502N     P=0.265N     P=0.372      P=0.532N    |P=0.501      P=0.745      P=0.178      P=0.401      |
|POLY 3             |     P=0.467N     P=0.258N     P=0.350      P=0.522N    |P=0.527      P=0.756      P=0.172      P=0.456      |
|POLY 1.5           |     P=0.465N     P=0.251N     P=0.343      P=0.513N    |P=0.549      P=0.758      P=0.174      P=0.472      |
|POLY 6             |     P=0.470N     P=0.266N     P=0.362      P=0.531N    |P=0.500      P=0.754      P=0.173      P=0.436      |
|LOGISTIC REGRESSION|     P=0.463N     P=0.213N     P=0.331      P=0.476N    |P=0.644N     P=0.759N     P=0.229      P=0.496      |
|COCH-ARM / FISHERS |     P=0.466N     P=0.247N     P=0.339      P=0.500N    |P=0.589      P=0.753N     P=0.181      P=0.500      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Liver                                                                                                                            |
|     Regeneration                                                                                                                |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     1/50 (2%)    4/50 (8%)    5/50 (10%)   0/50 (0%)   |2/50 (4%)    1/50 (2%)    0/50 (0%)    0/50 (0%)    |
|POLY-3 ADJUSTED (b)|     2.7%         11.2%        13.1%        0.0%        |5.1%         2.6%         0.0%         0.0%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    2/15 (13%)   0/13 (0%)   |1/19 (5%)    0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     729          566          566          ---         |716          590          ---          ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.089N     P=0.173      P=0.136      P=0.500N    |P=0.388N     P=0.529N     P=0.234N     P=0.369N     |
|POLY 3             |     P=0.090N     P=0.167      P=0.108      P=0.510N    |P=0.320N     P=0.507N     P=0.250N     P=0.269N     |
|POLY 1.5           |     P=0.086N     P=0.169      P=0.105      P=0.506N    |P=0.312N     P=0.504N     P=0.247N     P=0.257N     |
|POLY 6             |     P=0.094N     P=0.171      P=0.115      P=0.514N    |P=0.331N     P=0.508N     P=0.252N     P=0.284N     |
|LOGISTIC REGRESSION|     P=0.086N     P=0.177      P=0.111      P=0.506N    |P=0.320N     P=0.506N     P=0.247N     P=0.315N     |
|COCH-ARM / FISHERS |     P=0.083N     P=0.181      P=0.102      P=0.500N    |P=0.302N     P=0.500N     P=0.247N     P=0.247N     |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 23
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Liver                                                                                                                            |
|     Vacuolization Cytoplasmic Focal                                                                                             |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     1/50 (2%)    0/50 (0%)    0/50 (0%)    0/50 (0%)   |3/50 (6%)    0/50 (0%)    2/50 (4%)    0/50 (0%)    |
|POLY-3 ADJUSTED (b)|     2.7%         0.0%         0.0%         0.0%        |7.4%         0.0%         5.3%         0.0%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    0/13 (0%)   |0/19 (0%)    0/17 (0%)    1/21 (5%)    0/11 (0%)    |
|FIRST INCIDENCE    |     726          ---          ---          ---         |581          ---          547          ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.664N     P=0.529N     P=0.500N     P=0.514N    |P=0.280N     P=0.143N     P=0.512N     P=0.185N     |
|POLY 3             |     P=0.662N     P=0.514N     P=0.495N     P=0.510N    |P=0.240N     P=0.128N     P=0.531N     P=0.149N     |
|POLY 1.5           |     P=0.660N     P=0.510N     P=0.498N     P=0.506N    |P=0.229N     P=0.124N     P=0.522N     P=0.137N     |
|POLY 6             |     P=0.665N     P=0.518N     P=0.491N     P=0.514N    |P=0.255N     P=0.133N     P=0.539N     P=0.166N     |
|LOGISTIC REGRESSION|     P=0.668N     P=0.515N     P=0.485N     P=0.508N    |P=0.204N     P=0.117N     P=0.484N     P=0.110N     |
|COCH-ARM / FISHERS |     P=0.660N     P=0.500N     P=0.500N     P=0.500N    |P=0.213N     P=0.121N     P=0.500N     P=0.121N     |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Liver: Bile Duct                                                                                                                 |
|     Hyperplasia                                                                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     28/50 (56%)  27/50 (54%)  32/50 (64%)  30/50 (60%) |15/50 (30%)  12/50 (24%)  7/50 (14%)   13/50 (26%)  |
|POLY-3 ADJUSTED (b)|     64.0%        65.8%        71.0%        70.4%       |36.0%        29.1%        17.9%        34.6%        |
|TERMINAL (d)       |     7/13 (54%)   7/13 (54%)   9/15 (60%)   7/13 (54%)  |7/19 (37%)   3/17 (18%)   1/21 (5%)    1/11 (9%)    |
|FIRST INCIDENCE    |     534          524          450          520         |506          497          603          519          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.361      P=0.505      P=0.465      P=0.358     |P=0.163      P=0.414N     P=0.067N     P=0.380      |
|POLY 3             |     P=0.377      P=0.525      P=0.308      P=0.334     |P=0.342      P=0.330N     P=0.053N     P=0.543N     |
|POLY 1.5           |     P=0.397      P=0.560      P=0.288      P=0.360     |P=0.377      P=0.328N     P=0.052N     P=0.499N     |
|POLY 6             |     P=0.372      P=0.512      P=0.351      P=0.335     |P=0.312      P=0.330N     P=0.051N     P=0.579N     |
|LOGISTIC REGRESSION|     P=0.387      P=0.565      P=0.279      P=0.362     |P=0.372      P=0.339N     P=0.055N     P=0.541N     |
|COCH-ARM / FISHERS |     P=0.425      P=0.500N     P=0.270      P=0.420     |P=0.448      P=0.326N     P=0.045N*    P=0.412N     |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 24
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Liver: Bile Duct                                                                                                                 |
|     Inflammation Acute                                                                                                          |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/50 (0%)    0/50 (0%)    2/50 (4%)    0/50 (0%)   |0/50 (0%)    0/50 (0%)    0/50 (0%)    0/50 (0%)    |
|POLY-3 ADJUSTED (b)|     0.0%         0.0%         5.3%         0.0%        |0.0%         0.0%         0.0%         0.0%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    0/13 (0%)   |0/19 (0%)    0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     ---          ---          590          ---         |---          ---          ---          ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.574N     (e)          P=0.254      (e)         |(e)          (e)          (e)          (e)          |
|POLY 3             |     P=0.565N     (e)          P=0.245      (e)         |(e)          (e)          (e)          (e)          |
|POLY 1.5           |     P=0.564N     (e)          P=0.241      (e)         |(e)          (e)          (e)          (e)          |
|POLY 6             |     P=0.566N     (e)          P=0.252      (e)         |(e)          (e)          (e)          (e)          |
|LOGISTIC REGRESSION|     P=0.565N     (e)          P=0.236      (e)         |(e)          (e)          (e)          (e)          |
|COCH-ARM / FISHERS |     P=0.564N     (e)          P=0.247      (e)         |(e)          (e)          (e)          (e)          |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Liver: Centrilobular                                                                                                             |
|     Necrosis                                                                                                                    |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     13/50 (26%)  14/50 (28%)  16/50 (32%)  13/50 (26%) |6/50 (12%)   13/50 (26%)  8/50 (16%)   17/50 (34%)  |
|POLY-3 ADJUSTED (b)|     31.4%        34.0%        37.3%        33.4%       |14.5%        30.0%        19.9%        42.3%        |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    1/15 (7%)    0/13 (0%)   |0/19 (0%)    0/17 (0%)    0/21 (0%)    2/11 (18%)   |
|FIRST INCIDENCE    |     506          306          513          533         |506          497          354          418          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.510N     P=0.418      P=0.410      P=0.503     |P=0.007 **   P=0.071      P=0.338      P=0.004 **   |
|POLY 3             |     P=0.553N     P=0.493      P=0.365      P=0.519     |P=0.008 **   P=0.070      P=0.362      P=0.004 **   |
|POLY 1.5           |     P=0.512N     P=0.493      P=0.347      P=0.545     |P=0.010 *    P=0.066      P=0.366      P=0.004 **   |
|POLY 6             |     P=0.559      P=0.493      P=0.397      P=0.500     |P=0.007 **   P=0.079      P=0.369      P=0.003 **   |
|LOGISTIC REGRESSION|     P=0.414N     P=0.524N     P=0.306      P=0.564N    |P=0.026 *    P=0.067      P=0.434      P=0.011 *    |
|COCH-ARM / FISHERS |     P=0.448N     P=0.500      P=0.330      P=0.590N    |P=0.016 *    P=0.062      P=0.387      P=0.008 **   |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 25
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Lung                                                                                                                             |
|     Hyperplasia Atypical                                                                                                        |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/50 (0%)    2/49 (4%)    5/50 (10%)   18/50 (36%) |0/50 (0%)    0/50 (0%)    9/50 (18%)   16/50 (32%)  |
|POLY-3 ADJUSTED (b)|     0.0%         5.9%         13.0%        46.7%       |0.0%         0.0%         23.9%        43.1%        |
|TERMINAL (d)       |     0/13 (0%)    2/13 (15%)   2/15 (13%)   9/13 (69%)  |0/19 (0%)    0/17 (0%)    7/21 (33%)   6/11 (55%)   |
|FIRST INCIDENCE    |     ---          733 (T)      590          519         |---          ---          674          476          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P<0.001 **   P=0.235      P=0.046 *    P<0.001 **  |P<0.001 **   (e)          P=0.003 **   P<0.001 **   |
|POLY 3             |     P<0.001 **   P=0.220      P=0.033 *    P<0.001 **  |P<0.001 **   (e)          P<0.001 **   P<0.001 **   |
|POLY 1.5           |     P<0.001 **   P=0.224      P=0.032 *    P<0.001 **  |P<0.001 **   (e)          P<0.001 **   P<0.001 **   |
|POLY 6             |     P<0.001 **   P=0.216      P=0.036 *    P<0.001 **  |P<0.001 **   (e)          P<0.001 **   P<0.001 **   |
|LOGISTIC REGRESSION|     P<0.001 **   P=0.235      P=0.035 *    P<0.001 **  |P<0.001 **   (e)          P<0.001 **   P<0.001 **   |
|COCH-ARM / FISHERS |     P<0.001 **   P=0.242      P=0.028 *    P<0.001 **  |P<0.001 **   (e)          P<0.001 **   P<0.001 **   |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Lung                                                                                                                             |
|     Inflammation Chronic                                                                                                        |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     3/50 (6%)    43/49 (88%)  50/50 (100%) 50/50 (100%)|11/50 (22%)  46/50 (92%)  49/50 (98%)  50/50 (100%) |
|POLY-3 ADJUSTED (b)|     8.1%         93.5%        100.0%       100.0%      |26.7%        96.9%        99.8%        100.0%       |
|TERMINAL (d)       |     2/13 (15%)   12/13 (92%)  15/15 (100%) 13/13 (100%)|5/19 (26%)   17/17 (100%) 21/21 (100%) 11/11 (100%) |
|FIRST INCIDENCE    |     567          393          394          310         |506          310          198          215          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P<0.001 **   P<0.001 **   P<0.001 **   P<0.001 **  |P<0.001 **   P<0.001 **   P<0.001 **   P<0.001 **   |
|POLY 3             |     P<0.001 **   P<0.001 **   P<0.001 **   P<0.001 **  |P<0.001 **   P<0.001 **   P<0.001 **   P<0.001 **   |
|POLY 1.5           |     P<0.001 **   P<0.001 **   P<0.001 **   P<0.001 **  |P<0.001 **   P<0.001 **   P<0.001 **   P<0.001 **   |
|POLY 6             |     P<0.001 **   P<0.001 **   P<0.001 **   P<0.001 **  |P<0.001 **   P<0.001 **   P<0.001 **   P<0.001 **   |
|LOGISTIC REGRESSION|     P<0.001 **   P<0.001 **   P<0.001 **   P<0.001 **  |P<0.001 **   P<0.001 **   P<0.001 **   P<0.001 **   |
|COCH-ARM / FISHERS |     P<0.001 **   P<0.001 **   P<0.001 **   P<0.001 **  |P<0.001 **   P<0.001 **   P<0.001 **   P<0.001 **   |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 26
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Lung                                                                                                                             |
|     Metaplasia                                                                                                                  |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/50 (0%)    0/49 (0%)    1/50 (2%)    2/50 (4%)   |0/50 (0%)    0/50 (0%)    2/50 (4%)    1/50 (2%)    |
|POLY-3 ADJUSTED (b)|     0.0%         0.0%         2.7%         5.7%        |0.0%         0.0%         5.3%         2.9%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    1/15 (7%)    2/13 (15%)  |0/19 (0%)    0/17 (0%)    1/21 (5%)    0/11 (0%)    |
|FIRST INCIDENCE    |     ---          ---          733 (T)      733 (T)     |---          ---          678          677          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.116      (e)          P=0.529      P=0.235     |P=0.471      (e)          P=0.231      P=0.466      |
|POLY 3             |     P=0.125      (e)          P=0.505      P=0.225     |P=0.500      (e)          P=0.225      P=0.474      |
|POLY 1.5           |     P=0.127      (e)          P=0.502      P=0.230     |P=0.516      (e)          P=0.228      P=0.483      |
|POLY 6             |     P=0.122      (e)          P=0.509      P=0.220     |P=0.484      (e)          P=0.224      P=0.463      |
|LOGISTIC REGRESSION|     (e)          (e)          P=0.529      P=0.235     |P=0.506      (e)          P=0.223      P=0.479      |
|COCH-ARM / FISHERS |     P=0.130      (e)          P=0.500      P=0.247     |P=0.546      (e)          P=0.247      P=0.500      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Lung                                                                                                                             |
|     Mineralization                                                                                                              |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     4/50 (8%)    5/49 (10%)   3/50 (6%)    7/50 (14%)  |1/50 (2%)    0/50 (0%)    0/50 (0%)    1/50 (2%)    |
|POLY-3 ADJUSTED (b)|     10.6%        14.3%        7.9%         19.5%       |2.5%         0.0%         0.0%         2.9%         |
|TERMINAL (d)       |     0/13 (0%)    1/13 (8%)    1/15 (7%)    2/13 (15%)  |0/19 (0%)    0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     590          621          660          605         |703          ---          ---          712          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.153      P=0.451      P=0.460N     P=0.235     |P=0.423      P=0.508N     P=0.517N     P=0.679      |
|POLY 3             |     P=0.154      P=0.452      P=0.495N     P=0.226     |P=0.480      P=0.507N     P=0.512N     P=0.730      |
|POLY 1.5           |     P=0.164      P=0.463      P=0.497N     P=0.240     |P=0.489      P=0.504N     P=0.509N     P=0.742      |
|POLY 6             |     P=0.143      P=0.442      P=0.491N     P=0.214     |P=0.469      P=0.510N     P=0.515N     P=0.716      |
|LOGISTIC REGRESSION|     P=0.151      P=0.455      P=0.491N     P=0.227     |P=0.459      P=0.507N     P=0.513N     P=0.714      |
|COCH-ARM / FISHERS |     P=0.179      P=0.487      P=0.500N     P=0.262     |P=0.503      P=0.500N     P=0.500N     P=0.753N     |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 27
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Lung                                                                                                                             |
|     Proteinosis                                                                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/50 (0%)    22/49 (45%)  50/50 (100%) 49/50 (98%) |1/50 (2%)    24/50 (48%)  47/50 (94%)  49/50 (98%)  |
|POLY-3 ADJUSTED (b)|     0.0%         55.3%        100.0%       98.6%       |2.5%         57.4%        96.1%        99.3%        |
|TERMINAL (d)       |     0/13 (0%)    6/13 (46%)   15/15 (100%) 13/13 (100%)|1/19 (5%)    11/17 (65%)  20/21 (95%)  11/11 (100%) |
|FIRST INCIDENCE    |     ---          393          394          310         |734 (T)      559          198          215          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P<0.001 **   P<0.001 **   P<0.001 **   P<0.001 **  |P<0.001 **   P<0.001 **   P<0.001 **   P<0.001 **   |
|POLY 3             |     P<0.001 **   P<0.001 **   P<0.001 **   P<0.001 **  |P<0.001 **   P<0.001 **   P<0.001 **   P<0.001 **   |
|POLY 1.5           |     P<0.001 **   P<0.001 **   P<0.001 **   P<0.001 **  |P<0.001 **   P<0.001 **   P<0.001 **   P<0.001 **   |
|POLY 6             |     P<0.001 **   P<0.001 **   P<0.001 **   P<0.001 **  |P<0.001 **   P<0.001 **   P<0.001 **   P<0.001 **   |
|LOGISTIC REGRESSION|     P<0.001 **   P<0.001 **   P<0.001 **   P<0.001 **  |P<0.001 **   P<0.001 **   P<0.001 **   P<0.001 **   |
|COCH-ARM / FISHERS |     P<0.001 **   P<0.001 **   P<0.001 **   P<0.001 **  |P<0.001 **   P<0.001 **   P<0.001 **   P<0.001 **   |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Lung                                                                                                                             |
|     Thrombosis                                                                                                                  |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     1/50 (2%)    0/49 (0%)    0/50 (0%)    2/50 (4%)   |0/50 (0%)    1/50 (2%)    0/50 (0%)    0/50 (0%)    |
|POLY-3 ADJUSTED (b)|     2.7%         0.0%         0.0%         5.6%        |0.0%         2.6%         0.0%         0.0%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    0/13 (0%)   |0/19 (0%)    0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     684          ---          ---          520         |---          563          ---          ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.153      P=0.509N     P=0.500N     P=0.481     |P=0.693N     P=0.482      (e)          (e)          |
|POLY 3             |     P=0.161      P=0.516N     P=0.496N     P=0.492     |P=0.678N     P=0.497      (e)          (e)          |
|POLY 1.5           |     P=0.161      P=0.512N     P=0.498N     P=0.494     |P=0.673N     P=0.498      (e)          (e)          |
|POLY 6             |     P=0.162      P=0.520N     P=0.493N     P=0.492     |P=0.683N     P=0.496      (e)          (e)          |
|LOGISTIC REGRESSION|     P=0.171      P=0.516N     P=0.494N     P=0.534     |P=0.633N     P=0.501      (e)          (e)          |
|COCH-ARM / FISHERS |     P=0.161      P=0.505N     P=0.500N     P=0.500     |P=0.669N     P=0.500      (e)          (e)          |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 28
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Lung: Alveolar Epithelium                                                                                                        |
|     Hyperplasia                                                                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     12/50 (24%)  16/49 (33%)  21/50 (42%)  21/50 (42%) |14/50 (28%)  9/50 (18%)   17/50 (34%)  14/50 (28%)  |
|POLY-3 ADJUSTED (b)|     31.8%        43.8%        49.9%        53.7%       |34.1%        22.7%        42.7%        37.7%        |
|TERMINAL (d)       |     6/13 (46%)   9/13 (69%)   6/15 (40%)   9/13 (69%)  |6/19 (32%)   4/17 (24%)   10/21 (48%)  3/11 (27%)   |
|FIRST INCIDENCE    |     567          532          566          422         |581          559          534          506          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.096      P=0.203      P=0.108      P=0.043 *   |P=0.100      P=0.241N     P=0.352      P=0.223      |
|POLY 3             |     P=0.106      P=0.192      P=0.068      P=0.033 *   |P=0.319      P=0.184N     P=0.281      P=0.460      |
|POLY 1.5           |     P=0.112      P=0.202      P=0.053      P=0.036 *   |P=0.361      P=0.177N     P=0.291      P=0.505      |
|POLY 6             |     P=0.102      P=0.190      P=0.113      P=0.035 *   |P=0.279      P=0.194N     P=0.280      P=0.413      |
|LOGISTIC REGRESSION|     P=0.076      P=0.148      P=0.049 *    P=0.022 *   |P=0.287      P=0.191N     P=0.258      P=0.407      |
|COCH-ARM / FISHERS |     P=0.122      P=0.232      P=0.044 *    P=0.044 *   |P=0.446      P=0.171N     P=0.333      P=0.588N     |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Lung: Alveolar Epithelium                                                                                                        |
|     Metaplasia                                                                                                                  |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/50 (0%)    2/49 (4%)    34/50 (68%)  41/50 (82%) |0/50 (0%)    1/50 (2%)    36/50 (72%)  41/50 (82%)  |
|POLY-3 ADJUSTED (b)|     0.0%         5.8%         78.9%        90.9%       |0.0%         2.6%         82.7%        94.5%        |
|TERMINAL (d)       |     0/13 (0%)    1/13 (8%)    14/15 (93%)  13/13 (100%)|0/19 (0%)    1/17 (6%)    19/21 (91%)  11/11 (100%) |
|FIRST INCIDENCE    |     ---          548          443          422         |---          734 (T)      310          476          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P<0.001 **   P=0.237      P<0.001 **   P<0.001 **  |P<0.001 **   P=0.478      P<0.001 **   P<0.001 **   |
|POLY 3             |     P<0.001 **   P=0.223      P<0.001 **   P<0.001 **  |P<0.001 **   P=0.494      P<0.001 **   P<0.001 **   |
|POLY 1.5           |     P<0.001 **   P=0.226      P<0.001 **   P<0.001 **  |P<0.001 **   P=0.497      P<0.001 **   P<0.001 **   |
|POLY 6             |     P<0.001 **   P=0.222      P<0.001 **   P<0.001 **  |P<0.001 **   P=0.492      P<0.001 **   P<0.001 **   |
|LOGISTIC REGRESSION|     P<0.001 **   P=0.233      P<0.001 **   P<0.001 **  |P<0.001 **   P=0.478      P<0.001 **   P<0.001 **   |
|COCH-ARM / FISHERS |     P<0.001 **   P=0.242      P<0.001 **   P<0.001 **  |P<0.001 **   P=0.500      P<0.001 **   P<0.001 **   |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 29
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Lung: Artery, Mediastinum                                                                                                        |
|     Mineralization                                                                                                              |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     4/50 (8%)    3/49 (6%)    2/50 (4%)    5/50 (10%)  |0/50 (0%)    0/50 (0%)    0/50 (0%)    1/50 (2%)    |
|POLY-3 ADJUSTED (b)|     10.6%        8.7%         5.3%         14.0%       |0.0%         0.0%         0.0%         2.9%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    1/13 (8%)   |0/19 (0%)    0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     590          660          660          605         |---          ---          ---          712          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.243      P=0.546N     P=0.313N     P=0.442     |P=0.181      (e)          (e)          P=0.415      |
|POLY 3             |     P=0.261      P=0.548N     P=0.331N     P=0.466     |P=0.239      (e)          (e)          P=0.473      |
|POLY 1.5           |     P=0.270      P=0.535N     P=0.334N     P=0.479     |P=0.246      (e)          (e)          P=0.483      |
|POLY 6             |     P=0.252      P=0.563N     P=0.325N     P=0.455     |P=0.232      (e)          (e)          P=0.462      |
|LOGISTIC REGRESSION|     P=0.258      P=0.538N     P=0.334N     P=0.471     |P=0.218      (e)          (e)          P=0.450      |
|COCH-ARM / FISHERS |     P=0.281      P=0.511N     P=0.339N     P=0.500     |P=0.257      (e)          (e)          P=0.500      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Lymph Node, Mandibular                                                                                                           |
|     Infiltration Cellular Plasma Cell                                                                                           |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     2/46 (4%)    1/43 (2%)    1/46 (2%)    3/44 (7%)   |0/43 (0%)    0/45 (0%)    0/45 (0%)    0/47 (0%)    |
|POLY-3 ADJUSTED (b)|     5.7%         3.3%         2.9%         9.6%        |0.0%         0.0%         0.0%         0.0%         |
|TERMINAL (d)       |     0/12 (0%)    0/11 (0%)    0/14 (0%)    0/10 (0%)   |0/16 (0%)    0/17 (0%)    0/17 (0%)    0/9 (0%)     |
|FIRST INCIDENCE    |     506          548          674          310         |---          ---          ---          ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.232      P=0.519N     P=0.484N     P=0.466     |(e)          (e)          (e)          (e)          |
|POLY 3             |     P=0.232      P=0.546N     P=0.503N     P=0.450     |(e)          (e)          (e)          (e)          |
|POLY 1.5           |     P=0.239      P=0.538N     P=0.502N     P=0.463     |(e)          (e)          (e)          (e)          |
|POLY 6             |     P=0.224      P=0.556N     P=0.503N     P=0.435     |(e)          (e)          (e)          (e)          |
|LOGISTIC REGRESSION|     P=0.298      P=0.441N     P=0.508N     P=0.622     |(e)          (e)          (e)          (e)          |
|COCH-ARM / FISHERS |     P=0.246      P=0.526N     P=0.500N     P=0.479     |(e)          (e)          (e)          (e)          |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 30
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Mammary Gland                                                                                                                    |
|     Galactocele                                                                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     1/41 (2%)    2/42 (5%)    1/42 (2%)    3/40 (8%)   |1/50 (2%)    0/50 (0%)    2/50 (4%)    0/50 (0%)    |
|POLY-3 ADJUSTED (b)|     3.3%         6.9%         3.0%         10.2%       |2.5%         0.0%         5.3%         0.0%         |
|TERMINAL (d)       |     0/11 (0%)    1/9 (11%)    1/14 (7%)    0/12 (0%)   |0/19 (0%)    0/17 (0%)    1/21 (5%)    0/11 (0%)    |
|FIRST INCIDENCE    |     544          574          733 (T)      557         |716          ---          646          ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.235      P=0.469      P=0.731N     P=0.262     |P=0.507N     P=0.518N     P=0.500      P=0.614N     |
|POLY 3             |     P=0.230      P=0.485      P=0.742N     P=0.291     |P=0.436N     P=0.506N     P=0.482      P=0.528N     |
|POLY 1.5           |     P=0.231      P=0.494      P=0.747N     P=0.291     |P=0.423N     P=0.503N     P=0.486      P=0.517N     |
|POLY 6             |     P=0.234      P=0.470      P=0.736N     P=0.296     |P=0.452N     P=0.509N     P=0.481      P=0.540N     |
|LOGISTIC REGRESSION|     P=0.239      P=0.525      P=0.754      P=0.313     |P=0.439N     P=0.508N     P=0.479      P=0.555N     |
|COCH-ARM / FISHERS |     P=0.235      P=0.509      P=0.747N     P=0.298     |P=0.400N     P=0.500N     P=0.500      P=0.500N     |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Mesentery: Artery                                                                                                                |
|     Mineralization                                                                                                              |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     3/5 (60%)    2/10 (20%)   2/14 (14%)   2/7 (29%)   |0/6 (0%)     0/14 (0%)    0/6 (0%)     0/11 (0%)    |
|POLY-3 ADJUSTED (b)|     67.4%        27.6%        18.5%        35.6%       |0.0%         0.0%         0.0%         0.0%         |
|TERMINAL (d)       |     0/0 (0%)     0/2 (0%)     0/2 (0%)     0/1 (0%)    |0/1 (0%)     0/6 (0%)     0/4 (0%)     0/1 (0%)     |
|FIRST INCIDENCE    |     647          660          660          605         |---          ---          ---          ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.595N     P=0.535N     P=0.454N     P=0.528N    |(e)          (e)          (e)          (e)          |
|POLY 3             |     P=0.690N     P=0.216N     P=0.077N     P=0.353N    |(e)          (e)          (e)          (e)          |
|POLY 1.5           |     P=0.672      P=0.193N     P=0.072N     P=0.337N    |(e)          (e)          (e)          (e)          |
|POLY 6             |     P=0.677N     P=0.241N     P=0.089N     P=0.376N    |(e)          (e)          (e)          (e)          |
|LOGISTIC REGRESSION|     P=0.647      P=0.216N     P=0.093N     P=0.343N    |(e)          (e)          (e)          (e)          |
|COCH-ARM / FISHERS |     P=0.641      P=0.167N     P=0.084N     P=0.311N    |(e)          (e)          (e)          (e)          |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 31
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Mesentery: Fat                                                                                                                   |
|     Necrosis                                                                                                                    |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     3/5 (60%)    7/10 (70%)   11/14 (79%)  5/7 (71%)   |6/6 (100%)   13/14 (93%)  6/6 (100%)   11/11 (100%) |
|POLY-3 ADJUSTED (b)|     63.0%        84.9%        83.9%        73.5%       |100.0%       92.9%        100.0%       100.0%       |
|TERMINAL (d)       |     0/0 (0%)     2/2 (100%)   2/2 (100%)   1/1 (100%)  |1/1 (100%)   5/6 (83%)    4/4 (100%)   1/1 (100%)   |
|FIRST INCIDENCE    |     621          566          560          523         |588          478          462          478          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.467N     P=0.312      P=0.101      P=0.460     |P=0.026 *    P=0.298      (e)          (e)          |
|POLY 3             |     P=0.578N     P=0.406      P=0.376      P=0.601     |P=0.623      P=0.666N     (e)          (e)          |
|POLY 1.5           |     P=0.618N     P=0.473      P=0.395      P=0.588     |P=0.623      P=0.666N     (e)          (e)          |
|POLY 6             |     P=0.529N     P=0.346      P=0.345      P=0.626     |P=0.623      P=0.666N     (e)          (e)          |
|LOGISTIC REGRESSION|     P=0.666      P=0.424      P=0.438      P=0.595     |(e)          (e)          (e)          (e)          |
|COCH-ARM / FISHERS |     P=0.660      P=0.566      P=0.397      P=0.576     |P=0.627      P=0.700N     (e)          (e)          |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Nose                                                                                                                             |
|     Inflammation                                                                                                                |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     10/50 (20%)  5/48 (10%)   10/49 (20%)  8/50 (16%)  |3/50 (6%)    4/50 (8%)    9/49 (18%)   3/49 (6%)    |
|POLY-3 ADJUSTED (b)|     25.8%        14.5%        24.9%        21.6%       |7.5%         10.2%        23.6%        8.8%         |
|TERMINAL (d)       |     2/13 (15%)   2/13 (15%)   2/15 (13%)   1/13 (8%)   |0/19 (0%)    1/17 (6%)    4/21 (19%)   1/11 (9%)    |
|FIRST INCIDENCE    |     534          590          513          520         |589          590          534          688          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.539      P=0.189N     P=0.535N     P=0.463N    |P=0.543N     P=0.466      P=0.069      P=0.476      |
|POLY 3             |     P=0.568N     P=0.178N     P=0.568N     P=0.435N    |P=0.412N     P=0.486      P=0.044 *    P=0.587      |
|POLY 1.5           |     P=0.557N     P=0.167N     P=0.592N     P=0.422N    |P=0.375N     P=0.492      P=0.047 *    P=0.612      |
|POLY 6             |     P=0.576N     P=0.197N     P=0.527N     P=0.444N    |P=0.458N     P=0.481      P=0.044 *    P=0.557      |
|LOGISTIC REGRESSION|     P=0.557N     P=0.166N     P=0.576      P=0.422N    |P=0.380N     P=0.496      P=0.048 *    P=0.589      |
|COCH-ARM / FISHERS |     P=0.540N     P=0.150N     P=0.579      P=0.398N    |P=0.316N     P=0.500      P=0.056      P=0.651      |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 32
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Nose                                                                                                                             |
|     Thrombosis                                                                                                                  |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     4/50 (8%)    8/48 (17%)   8/49 (16%)   7/50 (14%)  |2/50 (4%)    7/50 (14%)   4/49 (8%)    6/49 (12%)   |
|POLY-3 ADJUSTED (b)|     10.5%        21.6%        20.3%        18.6%       |5.0%         17.4%        10.6%        16.4%        |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    1/15 (7%)    0/13 (0%)   |0/19 (0%)    0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     567          548          513          520         |607          509          603          476          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.482      P=0.163      P=0.226      P=0.246     |P=0.229      P=0.082      P=0.301      P=0.095      |
|POLY 3             |     P=0.510      P=0.158      P=0.189      P=0.251     |P=0.275      P=0.077      P=0.309      P=0.102      |
|POLY 1.5           |     P=0.516      P=0.155      P=0.179      P=0.253     |P=0.290      P=0.078      P=0.312      P=0.110      |
|POLY 6             |     P=0.510      P=0.168      P=0.209      P=0.258     |P=0.259      P=0.079      P=0.314      P=0.095      |
|LOGISTIC REGRESSION|     P=0.563      P=0.175      P=0.162      P=0.290     |P=0.355      P=0.083      P=0.331      P=0.162      |
|COCH-ARM / FISHERS |     P=0.531      P=0.159      P=0.168      P=0.262     |P=0.322      P=0.080      P=0.329      P=0.128      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Nose: Olfactory Epithelium                                                                                                       |
|     Atrophy                                                                                                                     |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     1/50 (2%)    2/48 (4%)    1/49 (2%)    2/50 (4%)   |0/50 (0%)    0/50 (0%)    0/49 (0%)    2/49 (4%)    |
|POLY-3 ADJUSTED (b)|     2.7%         5.8%         2.7%         5.7%        |0.0%         0.0%         0.0%         5.8%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    0/13 (0%)   |0/19 (0%)    0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     688          614          642          605         |---          ---          ---          554          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.481      P=0.477      P=0.737N     P=0.509     |P=0.026 *    (e)          (e)          P=0.180      |
|POLY 3             |     P=0.489      P=0.476      P=0.760N     P=0.486     |P=0.038 *    (e)          (e)          P=0.208      |
|POLY 1.5           |     P=0.496      P=0.479      P=0.760      P=0.491     |P=0.040 *    (e)          (e)          P=0.217      |
|POLY 6             |     P=0.484      P=0.475      P=0.755N     P=0.484     |P=0.036 *    (e)          (e)          P=0.200      |
|LOGISTIC REGRESSION|     P=0.497      P=0.474      P=0.760      P=0.487     |P=0.047 *    (e)          (e)          P=0.238      |
|COCH-ARM / FISHERS |     P=0.507      P=0.485      P=0.747      P=0.500     |P=0.044 *    (e)          (e)          P=0.242      |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 33
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Nose: Olfactory Epithelium                                                                                                       |
|     Degeneration Hyaline                                                                                                        |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     18/50 (36%)  26/48 (54%)  32/49 (65%)  25/50 (50%) |39/50 (78%)  38/50 (76%)  33/49 (67%)  32/49 (65%)  |
|POLY-3 ADJUSTED (b)|     43.8%        64.6%        70.8%        56.8%       |82.1%        80.4%        72.5%        73.7%        |
|TERMINAL (d)       |     7/13 (54%)   9/13 (69%)   7/15 (47%)   3/13 (23%)  |14/19 (74%)  13/17 (77%)  12/21 (57%)  7/11 (64%)   |
|FIRST INCIDENCE    |     534          524          394          422         |302          422          310          418          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.424      P=0.075      P=0.049 *    P=0.132     |P=0.291      P=0.481      P=0.277N     P=0.352      |
|POLY 3             |     P=0.470N     P=0.037 *    P=0.006 **   P=0.151     |P=0.278N     P=0.523N     P=0.186N     P=0.227N     |
|POLY 1.5           |     P=0.516N     P=0.040 *    P=0.004 **   P=0.129     |P=0.229N     P=0.516N     P=0.187N     P=0.190N     |
|POLY 6             |     P=0.401N     P=0.038 *    P=0.016 *    P=0.205     |P=0.339N     P=0.523N     P=0.177N     P=0.268N     |
|LOGISTIC REGRESSION|     P=0.548      P=0.043 *    P=0.003 **   P=0.127     |P=0.163N     P=0.507N     P=0.173N     P=0.160N     |
|COCH-ARM / FISHERS |     P=0.552      P=0.054      P=0.003 **   P=0.113     |P=0.138N     P=0.500N     P=0.168N     P=0.119N     |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Nose: Olfactory Epithelium                                                                                                       |
|     Metaplasia Respiratory                                                                                                      |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     2/50 (4%)    2/48 (4%)    1/49 (2%)    2/50 (4%)   |0/50 (0%)    2/50 (4%)    2/49 (4%)    1/49 (2%)    |
|POLY-3 ADJUSTED (b)|     5.3%         5.8%         2.7%         5.7%        |0.0%         5.2%         5.4%         2.9%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    0/13 (0%)   |0/19 (0%)    0/17 (0%)    1/21 (5%)    1/11 (9%)    |
|FIRST INCIDENCE    |     534          614          642          605         |---          660          646          734 (T)      |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.579      P=0.666      P=0.481N     P=0.689     |P=0.647      P=0.225      P=0.244      P=0.391      |
|POLY 3             |     P=0.587      P=0.665      P=0.503N     P=0.675     |P=0.670N     P=0.232      P=0.222      P=0.470      |
|POLY 1.5           |     P=0.595      P=0.669      P=0.505N     P=0.682     |P=0.654N     P=0.234      P=0.224      P=0.480      |
|POLY 6             |     P=0.580      P=0.661      P=0.498N     P=0.670     |P=0.681      P=0.231      P=0.223      P=0.459      |
|LOGISTIC REGRESSION|     P=0.609      P=0.685      P=0.513N     P=0.688N    |P=0.678N     P=0.232      P=0.223      P=0.391      |
|COCH-ARM / FISHERS |     P=0.607      P=0.676      P=0.508N     P=0.691N    |P=0.626N     P=0.247      P=0.242      P=0.495      |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 34
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Ovary                                                                                                                            |
|     Cyst                                                                                                                        |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |                                                        |7/50 (14%)   8/50 (16%)   10/50 (20%)  5/49 (10%)   |
|POLY-3 ADJUSTED (b)|                                                        |17.2%        20.5%        26.3%        14.0%        |
|TERMINAL (d)       |                                                        |2/19 (11%)   4/17 (24%)   7/21 (33%)   0/11 (0%)    |
|FIRST INCIDENCE    |                                                        |581          628          609          554          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |                                                        |P=0.478N     P=0.445      P=0.319      P=0.583N     |
|POLY 3             |                                                        |P=0.269N     P=0.464      P=0.236      P=0.471N     |
|POLY 1.5           |                                                        |P=0.250N     P=0.481      P=0.256      P=0.445N     |
|POLY 6             |                                                        |P=0.290N     P=0.447      P=0.218      P=0.500N     |
|LOGISTIC REGRESSION|                                                        |P=0.285N     P=0.473      P=0.247      P=0.414N     |
|COCH-ARM / FISHERS |                                                        |P=0.211N     P=0.500      P=0.298      P=0.394N     |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Pancreas                                                                                                                         |
|     Atrophy                                                                                                                     |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     24/49 (49%)  29/49 (59%)  25/50 (50%)  27/50 (54%) |15/50 (30%)  13/50 (26%)  21/50 (42%)  14/49 (29%)  |
|POLY-3 ADJUSTED (b)|     58.8%        71.8%        58.8%        62.0%       |35.7%        31.9%        49.3%        36.5%        |
|TERMINAL (d)       |     8/13 (62%)   12/13 (92%)  9/15 (60%)   4/13 (31%)  |6/19 (32%)   4/17 (24%)   8/21 (38%)   3/11 (27%)   |
|FIRST INCIDENCE    |     566          532          450          519         |506          497          339          418          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.393      P=0.181      P=0.488N     P=0.306     |P=0.296      P=0.507N     P=0.182      P=0.291      |
|POLY 3             |     P=0.498N     P=0.137      P=0.593N     P=0.470     |P=0.520N     P=0.449N     P=0.139      P=0.561      |
|POLY 1.5           |     P=0.559N     P=0.157      P=0.569      P=0.418     |P=0.490N     P=0.431N     P=0.138      P=0.587      |
|POLY 6             |     P=0.374N     P=0.117      P=0.573N     P=0.576     |P=0.548N     P=0.470N     P=0.149      P=0.539      |
|LOGISTIC REGRESSION|     P=0.454      P=0.121      P=0.570      P=0.343     |P=0.449N     P=0.428N     P=0.140      P=0.570N     |
|COCH-ARM / FISHERS |     P=0.512      P=0.209      P=0.540      P=0.383     |P=0.417N     P=0.412N     P=0.149      P=0.526N     |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 35
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Pancreas                                                                                                                         |
|     Basophilic Focus                                                                                                            |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     3/49 (6%)    3/49 (6%)    2/50 (4%)    3/50 (6%)   |4/50 (8%)    3/50 (6%)    1/50 (2%)    1/49 (2%)    |
|POLY-3 ADJUSTED (b)|     8.2%         8.7%         5.3%         8.5%        |10.0%        7.7%         2.7%         2.9%         |
|TERMINAL (d)       |     2/13 (15%)   2/13 (15%)   1/15 (7%)    2/13 (15%)  |2/19 (11%)   2/17 (12%)   1/21 (5%)    0/11 (0%)    |
|FIRST INCIDENCE    |     566          660          660          519         |607          422          734 (T)      556          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.551      P=0.643      P=0.451N     P=0.654     |P=0.352N     P=0.533N     P=0.176N     P=0.290N     |
|POLY 3             |     P=0.570      P=0.634      P=0.485N     P=0.650     |P=0.265N     P=0.513N     P=0.200N     P=0.225N     |
|POLY 1.5           |     P=0.578      P=0.643      P=0.488N     P=0.658     |P=0.254N     P=0.506N     P=0.194N     P=0.210N     |
|POLY 6             |     P=0.561      P=0.626      P=0.479N     P=0.643     |P=0.279N     P=0.523N     P=0.206N     P=0.244N     |
|LOGISTIC REGRESSION|     P=0.562      P=0.629      P=0.479N     P=0.652     |P=0.243N     P=0.501N     P=0.197N     P=0.199N     |
|COCH-ARM / FISHERS |     P=0.588      P=0.661N     P=0.490N     P=0.651N    |P=0.234N     P=0.500N     P=0.181N     P=0.187N     |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Pancreas                                                                                                                         |
|     Hyperplasia                                                                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     4/49 (8%)    3/49 (6%)    2/50 (4%)    1/50 (2%)   |3/50 (6%)    0/50 (0%)    1/50 (2%)    0/49 (0%)    |
|POLY-3 ADJUSTED (b)|     11.1%        8.7%         5.3%         2.9%        |7.6%         0.0%         2.7%         0.0%         |
|TERMINAL (d)       |     2/13 (15%)   1/13 (8%)    2/15 (13%)   1/13 (8%)   |2/19 (11%)   0/17 (0%)    1/21 (5%)    0/11 (0%)    |
|FIRST INCIDENCE    |     713          660          733 (T)      733 (T)     |699          ---          734 (T)      ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.209N     P=0.536N     P=0.287N     P=0.183N    |P=0.357N     P=0.135N     P=0.289N     P=0.215N     |
|POLY 3             |     P=0.207N     P=0.528N     P=0.318N     P=0.187N    |P=0.272N     P=0.124N     P=0.327N     P=0.147N     |
|POLY 1.5           |     P=0.201N     P=0.519N     P=0.323N     P=0.182N    |P=0.265N     P=0.121N     P=0.321N     P=0.138N     |
|POLY 6             |     P=0.214N     P=0.533N     P=0.309N     P=0.192N    |P=0.282N     P=0.126N     P=0.330N     P=0.159N     |
|LOGISTIC REGRESSION|     P=0.203N     P=0.547N     P=0.292N     P=0.178N    |P=0.320N     P=0.125N     P=0.321N     P=0.178N     |
|COCH-ARM / FISHERS |     P=0.193N     P=0.500N     P=0.329N     P=0.175N    |P=0.254N     P=0.121N     P=0.309N     P=0.125N     |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 36
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Pancreas: Artery                                                                                                                 |
|     Inflammation                                                                                                                |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     2/49 (4%)    0/49 (0%)    0/50 (0%)    1/50 (2%)   |0/50 (0%)    0/50 (0%)    0/50 (0%)    0/49 (0%)    |
|POLY-3 ADJUSTED (b)|     5.5%         0.0%         0.0%         2.9%        |0.0%         0.0%         0.0%         0.0%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    1/13 (8%)   |0/19 (0%)    0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     684          ---          ---          733 (T)     |---          ---          ---          ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.637      P=0.268N     P=0.233N     P=0.526N    |(e)          (e)          (e)          (e)          |
|POLY 3             |     P=0.653      P=0.251N     P=0.229N     P=0.514N    |(e)          (e)          (e)          (e)          |
|POLY 1.5           |     P=0.655      P=0.246N     P=0.231N     P=0.506N    |(e)          (e)          (e)          (e)          |
|POLY 6             |     P=0.651      P=0.256N     P=0.226N     P=0.525N    |(e)          (e)          (e)          (e)          |
|LOGISTIC REGRESSION|     P=0.643      P=0.254N     P=0.223N     P=0.521N    |(e)          (e)          (e)          (e)          |
|COCH-ARM / FISHERS |     P=0.656      P=0.247N     P=0.242N     P=0.492N    |(e)          (e)          (e)          (e)          |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Pancreas: Artery                                                                                                                 |
|     Mineralization                                                                                                              |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     3/49 (6%)    2/49 (4%)    1/50 (2%)    1/50 (2%)   |0/50 (0%)    0/50 (0%)    0/50 (0%)    0/49 (0%)    |
|POLY-3 ADJUSTED (b)|     8.2%         5.9%         2.6%         2.9%        |0.0%         0.0%         0.0%         0.0%         |
|TERMINAL (d)       |     0/13 (0%)    1/13 (8%)    0/15 (0%)    0/13 (0%)   |0/19 (0%)    0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     647          708          660          715         |---          ---          ---          ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.403N     P=0.532N     P=0.288N     P=0.356N    |(e)          (e)          (e)          (e)          |
|POLY 3             |     P=0.379N     P=0.532N     P=0.292N     P=0.321N    |(e)          (e)          (e)          (e)          |
|POLY 1.5           |     P=0.371N     P=0.521N     P=0.295N     P=0.312N    |(e)          (e)          (e)          (e)          |
|POLY 6             |     P=0.389N     P=0.548N     P=0.288N     P=0.333N    |(e)          (e)          (e)          (e)          |
|LOGISTIC REGRESSION|     P=0.382N     P=0.537N     P=0.291N     P=0.323N    |(e)          (e)          (e)          (e)          |
|COCH-ARM / FISHERS |     P=0.360N     P=0.500N     P=0.301N     P=0.301N    |(e)          (e)          (e)          (e)          |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 37
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Parathyroid Gland                                                                                                                |
|     Hyperplasia                                                                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     13/47 (28%)  13/48 (27%)  17/47 (36%)  16/48 (33%) |0/47 (0%)    3/42 (7%)    3/47 (6%)    3/46 (7%)    |
|POLY-3 ADJUSTED (b)|     34.3%        36.7%        43.6%        42.9%       |0.0%         9.5%         8.6%         9.4%         |
|TERMINAL (d)       |     2/12 (17%)   5/13 (39%)   3/14 (21%)   5/13 (39%)  |0/18 (0%)    0/12 (0%)    2/19 (11%)   1/10 (10%)   |
|FIRST INCIDENCE    |     534          306          394          519         |---          700          660          677          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.312      P=0.520      P=0.371      P=0.294     |P=0.204      P=0.124      P=0.121      P=0.064      |
|POLY 3             |     P=0.344      P=0.513      P=0.270      P=0.293     |P=0.332      P=0.091      P=0.108      P=0.094      |
|POLY 1.5           |     P=0.357      P=0.552      P=0.262      P=0.315     |P=0.351      P=0.094      P=0.111      P=0.101      |
|POLY 6             |     P=0.331      P=0.468      P=0.289      P=0.271     |P=0.314      P=0.088      P=0.107      P=0.088      |
|LOGISTIC REGRESSION|     P=0.354      P=0.567      P=0.258      P=0.324     |P=0.308      P=0.087      P=0.108      P=0.083      |
|COCH-ARM / FISHERS |     P=0.373      P=0.566N     P=0.254      P=0.353     |P=0.387      P=0.101      P=0.121      P=0.117      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Pituitary Gland                                                                                                                  |
|     Angiectasis                                                                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/49 (0%)    1/49 (2%)    0/50 (0%)    1/50 (2%)   |0/50 (0%)    0/50 (0%)    2/50 (4%)    1/49 (2%)    |
|POLY-3 ADJUSTED (b)|     0.0%         2.9%         0.0%         2.9%        |0.0%         0.0%         5.3%         2.9%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    1/13 (8%)   |0/19 (0%)    0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     ---          524          ---          733 (T)     |---          ---          609          674          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.485      P=0.492      (e)          P=0.500     |P=0.513      (e)          P=0.216      P=0.480      |
|POLY 3             |     P=0.487      P=0.493      (e)          P=0.494     |P=0.498      (e)          P=0.227      P=0.471      |
|POLY 1.5           |     P=0.492      P=0.495      (e)          P=0.498     |P=0.512      (e)          P=0.229      P=0.480      |
|POLY 6             |     P=0.482      P=0.493      (e)          P=0.491     |P=0.484      (e)          P=0.228      P=0.462      |
|LOGISTIC REGRESSION|     P=0.504      P=0.570      (e)          P=0.500     |P=0.535      (e)          P=0.240      P=0.479      |
|COCH-ARM / FISHERS |     P=0.500      P=0.500      (e)          P=0.505     |P=0.540      (e)          P=0.247      P=0.495      |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 38
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Pituitary Gland: Pars Distalis                                                                                                   |
|     Angiectasis                                                                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/49 (0%)    0/49 (0%)    0/50 (0%)    0/50 (0%)   |0/50 (0%)    0/50 (0%)    0/50 (0%)    2/49 (4%)    |
|POLY-3 ADJUSTED (b)|     0.0%         0.0%         0.0%         0.0%        |0.0%         0.0%         0.0%         5.9%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    0/13 (0%)   |0/19 (0%)    0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     ---          ---          ---          ---         |---          ---          ---          703          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     (e)          (e)          (e)          (e)         |P=0.018 *    (e)          (e)          P=0.153      |
|POLY 3             |     (e)          (e)          (e)          (e)         |P=0.037 *    (e)          (e)          P=0.205      |
|POLY 1.5           |     (e)          (e)          (e)          (e)         |P=0.039 *    (e)          (e)          P=0.215      |
|POLY 6             |     (e)          (e)          (e)          (e)         |P=0.034 *    (e)          (e)          P=0.195      |
|LOGISTIC REGRESSION|     (e)          (e)          (e)          (e)         |P=0.026 *    (e)          (e)          P=0.177      |
|COCH-ARM / FISHERS |     (e)          (e)          (e)          (e)         |P=0.044 *    (e)          (e)          P=0.242      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Pituitary Gland: Pars Distalis                                                                                                   |
|     Hyperplasia                                                                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     17/49 (35%)  12/49 (24%)  15/50 (30%)  12/50 (24%) |5/50 (10%)   3/50 (6%)    7/50 (14%)   9/49 (18%)   |
|POLY-3 ADJUSTED (b)|     42.6%        32.0%        36.4%        31.2%       |11.8%        7.5%         18.2%        24.0%        |
|TERMINAL (d)       |     6/13 (46%)   4/13 (31%)   5/15 (33%)   3/13 (23%)  |0/19 (0%)    0/17 (0%)    2/21 (10%)   2/11 (18%)   |
|FIRST INCIDENCE    |     566          548          394          523         |302          422          534          215          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.368N     P=0.276N     P=0.321N     P=0.267N    |P=0.038 *    P=0.379N     P=0.360      P=0.110      |
|POLY 3             |     P=0.301N     P=0.225N     P=0.360N     P=0.200N    |P=0.054      P=0.383N     P=0.312      P=0.126      |
|POLY 1.5           |     P=0.288N     P=0.213N     P=0.370N     P=0.189N    |P=0.062      P=0.373N     P=0.331      P=0.145      |
|POLY 6             |     P=0.316N     P=0.241N     P=0.348N     P=0.214N    |P=0.045 *    P=0.392N     P=0.302      P=0.107      |
|LOGISTIC REGRESSION|     P=0.282N     P=0.209N     P=0.381N     P=0.186N    |P=0.136      P=0.303N     P=0.433      P=0.329      |
|COCH-ARM / FISHERS |     P=0.271N     P=0.188N     P=0.388N     P=0.172N    |P=0.079      P=0.357N     P=0.380      P=0.183      |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 39
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Preputial Gland                                                                                                                  |
|     Hyperplasia                                                                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     1/50 (2%)    0/49 (0%)    3/50 (6%)    4/49 (8%)   |                                                    |
|POLY-3 ADJUSTED (b)|     2.7%         0.0%         7.7%         11.3%       |                                                    |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    2/13 (15%)  |                                                    |
|FIRST INCIDENCE    |     636          ---          394          605         |                                                    |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.073      P=0.534N     P=0.317      P=0.159     |                                                    |
|POLY 3             |     P=0.078      P=0.522N     P=0.324      P=0.163     |                                                    |
|POLY 1.5           |     P=0.078      P=0.516N     P=0.316      P=0.167     |                                                    |
|POLY 6             |     P=0.079      P=0.528N     P=0.334      P=0.160     |                                                    |
|LOGISTIC REGRESSION|     P=0.077      P=0.503N     P=0.286      P=0.166     |                                                    |
|COCH-ARM / FISHERS |     P=0.077      P=0.505N     P=0.309      P=0.175     |                                                    |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Preputial Gland                                                                                                                  |
|     Inflammation Chronic                                                                                                        |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     4/50 (8%)    4/49 (8%)    8/50 (16%)   3/49 (6%)   |                                                    |
|POLY-3 ADJUSTED (b)|     10.8%        11.7%        20.5%        8.6%        |                                                    |
|TERMINAL (d)       |     1/13 (8%)    1/13 (8%)    2/15 (13%)   1/13 (8%)   |                                                    |
|FIRST INCIDENCE    |     647          587          601          645         |                                                    |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.314N     P=0.593      P=0.243      P=0.551N    |                                                    |
|POLY 3             |     P=0.302N     P=0.601      P=0.195      P=0.531N    |                                                    |
|POLY 1.5           |     P=0.296N     P=0.608      P=0.186      P=0.524N    |                                                    |
|POLY 6             |     P=0.313N     P=0.601      P=0.214      P=0.539N    |                                                    |
|LOGISTIC REGRESSION|     P=0.303N     P=0.587      P=0.193      P=0.538N    |                                                    |
|COCH-ARM / FISHERS |     P=0.294N     P=0.631      P=0.178      P=0.511N    |                                                    |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 40
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Prostate                                                                                                                         |
|     Hyperplasia                                                                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     12/50 (24%)  9/48 (19%)   11/50 (22%)  7/50 (14%)  |                                                    |
|POLY-3 ADJUSTED (b)|     31.6%        25.2%        27.9%        19.9%       |                                                    |
|TERMINAL (d)       |     6/13 (46%)   4/13 (31%)   3/15 (20%)   6/13 (46%)  |                                                    |
|FIRST INCIDENCE    |     621          548          590          621         |                                                    |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.215N     P=0.372N     P=0.389N     P=0.168N    |                                                    |
|POLY 3             |     P=0.214N     P=0.360N     P=0.457N     P=0.185N    |                                                    |
|POLY 1.5           |     P=0.192N     P=0.357N     P=0.479N     P=0.171N    |                                                    |
|POLY 6             |     P=0.251N     P=0.362N     P=0.418N     P=0.206N    |                                                    |
|LOGISTIC REGRESSION|     P=0.201N     P=0.391N     P=0.451N     P=0.178N    |                                                    |
|COCH-ARM / FISHERS |     P=0.165N     P=0.350N     P=0.500N     P=0.154N    |                                                    |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Prostate                                                                                                                         |
|     Inflammation Chronic                                                                                                        |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     3/50 (6%)    1/48 (2%)    6/50 (12%)   2/50 (4%)   |                                                    |
|POLY-3 ADJUSTED (b)|     8.1%         2.9%         15.4%        5.7%        |                                                    |
|TERMINAL (d)       |     1/13 (8%)    0/13 (0%)    1/15 (7%)    1/13 (8%)   |                                                    |
|FIRST INCIDENCE    |     684          532          601          668         |                                                    |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.453N     P=0.325N     P=0.299      P=0.516N    |                                                    |
|POLY 3             |     P=0.440N     P=0.326N     P=0.265      P=0.523N    |                                                    |
|POLY 1.5           |     P=0.431N     P=0.324N     P=0.253      P=0.514N    |                                                    |
|POLY 6             |     P=0.450N     P=0.327N     P=0.288      P=0.530N    |                                                    |
|LOGISTIC REGRESSION|     P=0.440N     P=0.329N     P=0.257      P=0.531N    |                                                    |
|COCH-ARM / FISHERS |     P=0.415N     P=0.324N     P=0.243      P=0.500N    |                                                    |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 41
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Seminal Vesicle                                                                                                                  |
|     Mineralization                                                                                                              |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     2/45 (4%)    1/47 (2%)    1/48 (2%)    0/50 (0%)   |                                                    |
|POLY-3 ADJUSTED (b)|     5.9%         3.0%         2.8%         0.0%        |                                                    |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    1/15 (7%)    0/13 (0%)   |                                                    |
|FIRST INCIDENCE    |     647          708          733 (T)      ---         |                                                    |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.276N     P=0.536N     P=0.469N     P=0.281N    |                                                    |
|POLY 3             |     P=0.250N     P=0.504N     P=0.476N     P=0.230N    |                                                    |
|POLY 1.5           |     P=0.245N     P=0.497N     P=0.476N     P=0.223N    |                                                    |
|POLY 6             |     P=0.257N     P=0.515N     P=0.476N     P=0.239N    |                                                    |
|LOGISTIC REGRESSION|     P=0.255N     P=0.508N     P=0.467N     P=0.231N    |                                                    |
|COCH-ARM / FISHERS |     P=0.237N     P=0.484N     P=0.476N     P=0.222N    |                                                    |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Skin                                                                                                                             |
|     Hyperkeratosis                                                                                                              |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     1/50 (2%)    0/49 (0%)    2/50 (4%)    0/50 (0%)   |0/50 (0%)    0/50 (0%)    0/50 (0%)    0/50 (0%)    |
|POLY-3 ADJUSTED (b)|     2.7%         0.0%         5.3%         0.0%        |0.0%         0.0%         0.0%         0.0%         |
|TERMINAL (d)       |     1/13 (8%)    0/13 (0%)    2/15 (13%)   0/13 (0%)   |0/19 (0%)    0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     733 (T)      ---          733 (T)      ---         |---          ---          ---          ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.408N     P=0.500N     P=0.551      P=0.500N    |(e)          (e)          (e)          (e)          |
|POLY 3             |     P=0.400N     P=0.517N     P=0.508      P=0.510N    |(e)          (e)          (e)          (e)          |
|POLY 1.5           |     P=0.398N     P=0.513N     P=0.504      P=0.506N    |(e)          (e)          (e)          (e)          |
|POLY 6             |     P=0.403N     P=0.519N     P=0.516      P=0.513N    |(e)          (e)          (e)          (e)          |
|LOGISTIC REGRESSION|     P=0.408N     (e)          P=0.551      (e)         |(e)          (e)          (e)          (e)          |
|COCH-ARM / FISHERS |     P=0.398N     P=0.505N     P=0.500      P=0.500N    |(e)          (e)          (e)          (e)          |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 42
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Skin                                                                                                                             |
|     Inflammation Chronic                                                                                                        |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/50 (0%)    0/49 (0%)    3/50 (6%)    2/50 (4%)   |0/50 (0%)    0/50 (0%)    0/50 (0%)    0/50 (0%)    |
|POLY-3 ADJUSTED (b)|     0.0%         0.0%         7.8%         5.7%        |0.0%         0.0%         0.0%         0.0%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    1/15 (7%)    1/13 (8%)   |0/19 (0%)    0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     ---          ---          443          621         |---          ---          ---          ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.287      (e)          P=0.138      P=0.226     |(e)          (e)          (e)          (e)          |
|POLY 3             |     P=0.311      (e)          P=0.126      P=0.227     |(e)          (e)          (e)          (e)          |
|POLY 1.5           |     P=0.312      (e)          P=0.123      P=0.231     |(e)          (e)          (e)          (e)          |
|POLY 6             |     P=0.312      (e)          P=0.132      P=0.225     |(e)          (e)          (e)          (e)          |
|LOGISTIC REGRESSION|     P=0.312      (e)          P=0.116      P=0.226     |(e)          (e)          (e)          (e)          |
|COCH-ARM / FISHERS |     P=0.311      (e)          P=0.121      P=0.247     |(e)          (e)          (e)          (e)          |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Spleen                                                                                                                           |
|     Fibrosis                                                                                                                    |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     13/50 (26%)  12/50 (24%)  17/50 (34%)  12/50 (24%) |4/50 (8%)    6/50 (12%)   5/50 (10%)   1/49 (2%)    |
|POLY-3 ADJUSTED (b)|     32.8%        33.1%        42.9%        33.2%       |10.1%        15.1%        13.1%        2.9%         |
|TERMINAL (d)       |     4/13 (31%)   3/13 (23%)   9/15 (60%)   7/13 (54%)  |2/19 (11%)   2/17 (12%)   2/21 (10%)   0/11 (0%)    |
|FIRST INCIDENCE    |     506          574          566          605         |677          523          605          730          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.457N     P=0.545N     P=0.372      P=0.541N    |P=0.153N     P=0.329      P=0.492      P=0.350N     |
|POLY 3             |     P=0.475N     P=0.589      P=0.235      P=0.585     |P=0.099N     P=0.368      P=0.474      P=0.228N     |
|POLY 1.5           |     P=0.434N     P=0.574N     P=0.244      P=0.566N    |P=0.087N     P=0.369      P=0.479      P=0.211N     |
|POLY 6             |     P=0.537N     P=0.572      P=0.227      P=0.536     |P=0.118N     P=0.371      P=0.479      P=0.249N     |
|LOGISTIC REGRESSION|     P=0.451N     P=0.578N     P=0.281      P=0.570N    |P=0.086N     P=0.358      P=0.463      P=0.270N     |
|COCH-ARM / FISHERS |     P=0.393N     P=0.500N     P=0.257      P=0.500N    |P=0.069N     P=0.370      P=0.500      P=0.187N     |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 43
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Spleen                                                                                                                           |
|     Hematopoietic Cell Proliferation                                                                                            |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     4/50 (8%)    2/50 (4%)    6/50 (12%)   1/50 (2%)   |5/50 (10%)   2/50 (4%)    6/50 (12%)   1/49 (2%)    |
|POLY-3 ADJUSTED (b)|     10.5%        5.7%         15.4%        2.8%        |12.0%        5.1%         15.2%        2.9%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    0/13 (0%)   |0/19 (0%)    1/17 (6%)    1/21 (5%)    0/11 (0%)    |
|FIRST INCIDENCE    |     566          534          621          645         |497          422          448          684          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.184N     P=0.387N     P=0.412      P=0.225N    |P=0.187N     P=0.247N     P=0.468      P=0.163N     |
|POLY 3             |     P=0.158N     P=0.370N     P=0.383      P=0.200N    |P=0.168N     P=0.240N     P=0.464      P=0.152N     |
|POLY 1.5           |     P=0.151N     P=0.360N     P=0.376      P=0.192N    |P=0.149N     P=0.229N     P=0.474      P=0.133N     |
|POLY 6             |     P=0.168N     P=0.380N     P=0.400      P=0.211N    |P=0.193N     P=0.256N     P=0.456      P=0.178N     |
|LOGISTIC REGRESSION|     P=0.145N     P=0.293N     P=0.370      P=0.174N    |P=0.090N     P=0.201N     P=0.569      P=0.084N     |
|COCH-ARM / FISHERS |     P=0.146N     P=0.339N     P=0.370      P=0.181N    |P=0.120N     P=0.218N     P=0.500      P=0.107N     |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Spleen                                                                                                                           |
|     Hemorrhage                                                                                                                  |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/50 (0%)    0/50 (0%)    0/50 (0%)    0/50 (0%)   |0/50 (0%)    0/50 (0%)    1/50 (2%)    2/49 (4%)    |
|POLY-3 ADJUSTED (b)|     0.0%         0.0%         0.0%         0.0%        |0.0%         0.0%         2.7%         5.8%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    0/13 (0%)   |0/19 (0%)    0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     ---          ---          ---          ---         |---          ---          701          631          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     (e)          (e)          (e)          (e)         |P=0.104      (e)          P=0.483      P=0.217      |
|POLY 3             |     (e)          (e)          (e)          (e)         |P=0.107      (e)          P=0.489      P=0.208      |
|POLY 1.5           |     (e)          (e)          (e)          (e)         |P=0.112      (e)          P=0.492      P=0.216      |
|POLY 6             |     (e)          (e)          (e)          (e)         |P=0.102      (e)          P=0.488      P=0.200      |
|LOGISTIC REGRESSION|     (e)          (e)          (e)          (e)         |P=0.113      (e)          P=0.488      P=0.226      |
|COCH-ARM / FISHERS |     (e)          (e)          (e)          (e)         |P=0.124      (e)          P=0.500      P=0.242      |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 44
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Spleen                                                                                                                           |
|     Inflammation Granulomatous                                                                                                  |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     2/50 (4%)    0/50 (0%)    0/50 (0%)    0/50 (0%)   |0/50 (0%)    0/50 (0%)    0/50 (0%)    0/49 (0%)    |
|POLY-3 ADJUSTED (b)|     5.4%         0.0%         0.0%         0.0%        |0.0%         0.0%         0.0%         0.0%         |
|TERMINAL (d)       |     1/13 (8%)    0/13 (0%)    0/15 (0%)    0/13 (0%)   |0/19 (0%)    0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     506          ---          ---          ---         |---          ---          ---          ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.434N     P=0.247N     P=0.228N     P=0.244N    |(e)          (e)          (e)          (e)          |
|POLY 3             |     P=0.427N     P=0.257N     P=0.235N     P=0.252N    |(e)          (e)          (e)          (e)          |
|POLY 1.5           |     P=0.426N     P=0.250N     P=0.236N     P=0.246N    |(e)          (e)          (e)          (e)          |
|POLY 6             |     P=0.429N     P=0.262N     P=0.232N     P=0.257N    |(e)          (e)          (e)          (e)          |
|LOGISTIC REGRESSION|     P=0.426N     P=0.223N     P=0.242N     P=0.225N    |(e)          (e)          (e)          (e)          |
|COCH-ARM / FISHERS |     P=0.429N     P=0.247N     P=0.247N     P=0.247N    |(e)          (e)          (e)          (e)          |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Spleen                                                                                                                           |
|     Necrosis                                                                                                                    |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/50 (0%)    1/50 (2%)    5/50 (10%)   0/50 (0%)   |0/50 (0%)    1/50 (2%)    1/50 (2%)    0/49 (0%)    |
|POLY-3 ADJUSTED (b)|     0.0%         2.9%         12.6%        0.0%        |0.0%         2.6%         2.7%         0.0%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    0/13 (0%)   |0/19 (0%)    0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     ---          642          513          ---         |---          631          603          ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.264N     P=0.472      P=0.042 *    (e)         |P=0.532N     P=0.483      P=0.500      (e)          |
|POLY 3             |     P=0.241N     P=0.488      P=0.037 *    (e)         |P=0.537N     P=0.496      P=0.491      (e)          |
|POLY 1.5           |     P=0.239N     P=0.491      P=0.034 *    (e)         |P=0.526N     P=0.498      P=0.493      (e)          |
|POLY 6             |     P=0.243N     P=0.486      P=0.043 *    (e)         |P=0.549N     P=0.495      P=0.491      (e)          |
|LOGISTIC REGRESSION|     P=0.237N     P=0.498      P=0.029 *    (e)         |P=0.490N     P=0.503      P=0.520      (e)          |
|COCH-ARM / FISHERS |     P=0.243N     P=0.500      P=0.028 *    (e)         |P=0.508N     P=0.500      P=0.500      (e)          |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 45
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Stomach, Forestomach                                                                                                             |
|     Hyperplasia                                                                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/49 (0%)    0/50 (0%)    1/50 (2%)    0/50 (0%)   |0/50 (0%)    1/50 (2%)    1/50 (2%)    2/50 (4%)    |
|POLY-3 ADJUSTED (b)|     0.0%         0.0%         2.6%         0.0%        |0.0%         2.6%         2.7%         5.6%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    0/13 (0%)   |0/19 (0%)    0/17 (0%)    1/21 (5%)    0/11 (0%)    |
|FIRST INCIDENCE    |     ---          ---          642          ---         |---          478          734 (T)      519          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.770N     (e)          P=0.512      (e)         |P=0.197      P=0.500      P=0.520      P=0.211      |
|POLY 3             |     P=0.744N     (e)          P=0.510      (e)         |P=0.225      P=0.498      P=0.488      P=0.213      |
|POLY 1.5           |     P=0.742N     (e)          P=0.507      (e)         |P=0.235      P=0.499      P=0.491      P=0.221      |
|POLY 6             |     P=0.745N     (e)          P=0.515      (e)         |P=0.215      P=0.497      P=0.487      P=0.205      |
|LOGISTIC REGRESSION|     P=0.741N     (e)          P=0.503      (e)         |P=0.297      P=0.482      P=0.520      P=0.278      |
|COCH-ARM / FISHERS |     P=0.741N     (e)          P=0.505      (e)         |P=0.254      P=0.500      P=0.500      P=0.247      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Stomach, Forestomach                                                                                                             |
|     Mineralization                                                                                                              |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     2/49 (4%)    2/50 (4%)    2/50 (4%)    2/50 (4%)   |0/50 (0%)    0/50 (0%)    0/50 (0%)    1/50 (2%)    |
|POLY-3 ADJUSTED (b)|     5.5%         5.8%         5.3%         5.7%        |0.0%         0.0%         0.0%         2.9%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    0/13 (0%)   |0/19 (0%)    0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     647          660          660          605         |---          ---          ---          712          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.610      P=0.645      P=0.664N     P=0.646     |P=0.181      (e)          (e)          P=0.415      |
|POLY 3             |     P=0.642      P=0.676      P=0.680N     P=0.685     |P=0.239      (e)          (e)          P=0.473      |
|POLY 1.5           |     P=0.647      P=0.683      P=0.683N     P=0.691     |P=0.246      (e)          (e)          P=0.483      |
|POLY 6             |     P=0.636      P=0.670      P=0.674N     P=0.680     |P=0.232      (e)          (e)          P=0.462      |
|LOGISTIC REGRESSION|     P=0.642      P=0.672      P=0.683N     P=0.686     |P=0.218      (e)          (e)          P=0.450      |
|COCH-ARM / FISHERS |     P=0.647N     P=0.684N     P=0.684N     P=0.684N    |P=0.257      (e)          (e)          P=0.500      |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 46
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Stomach, Forestomach                                                                                                             |
|     Necrosis                                                                                                                    |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     7/49 (14%)   10/50 (20%)  9/50 (18%)   11/50 (22%) |4/50 (8%)    7/50 (14%)   3/50 (6%)    4/50 (8%)    |
|POLY-3 ADJUSTED (b)|     18.4%        25.9%        22.4%        28.2%       |9.9%         17.2%        7.8%         11.4%        |
|TERMINAL (d)       |     1/13 (8%)    0/13 (0%)    1/15 (7%)    1/13 (8%)   |0/19 (0%)    0/17 (0%)    0/21 (0%)    1/11 (9%)    |
|FIRST INCIDENCE    |     544          393          560          520         |607          497          462          631          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.255      P=0.235      P=0.453      P=0.203     |P=0.600      P=0.248      P=0.540N     P=0.463      |
|POLY 3             |     P=0.286      P=0.303      P=0.440      P=0.225     |P=0.552N     P=0.262      P=0.525N     P=0.562      |
|POLY 1.5           |     P=0.289      P=0.300      P=0.425      P=0.224     |P=0.516N     P=0.262      P=0.519N     P=0.593      |
|POLY 6             |     P=0.288      P=0.318      P=0.466      P=0.235     |P=0.598N     P=0.265      P=0.529N     P=0.523      |
|LOGISTIC REGRESSION|     P=0.310      P=0.366      P=0.406      P=0.248     |P=0.447N     P=0.269      P=0.473N     P=0.582      |
|COCH-ARM / FISHERS |     P=0.296      P=0.314      P=0.410      P=0.232     |P=0.459N     P=0.262      P=0.500N     P=0.643N     |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Stomach, Glandular                                                                                                               |
|     Mineralization                                                                                                              |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     8/49 (16%)   6/49 (12%)   8/50 (16%)   8/50 (16%)  |2/50 (4%)    1/50 (2%)    2/50 (4%)    3/49 (6%)    |
|POLY-3 ADJUSTED (b)|     21.4%        17.2%        20.5%        22.1%       |5.0%         2.6%         5.3%         8.7%         |
|TERMINAL (d)       |     2/13 (15%)   2/13 (15%)   2/15 (13%)   2/13 (15%)  |1/19 (5%)    1/17 (6%)    1/21 (5%)    1/11 (9%)    |
|FIRST INCIDENCE    |     590          621          590          605         |660          734 (T)      630          534          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.434      P=0.447N     P=0.535N     P=0.546     |P=0.175      P=0.536N     P=0.686N     P=0.340      |
|POLY 3             |     P=0.469      P=0.437N     P=0.574N     P=0.586     |P=0.272      P=0.513N     P=0.675      P=0.438      |
|POLY 1.5           |     P=0.483      P=0.419N     P=0.582N     P=0.600     |P=0.286      P=0.507N     P=0.679      P=0.457      |
|POLY 6             |     P=0.457      P=0.458N     P=0.558N     P=0.575     |P=0.256      P=0.520N     P=0.673      P=0.416      |
|LOGISTIC REGRESSION|     P=0.448      P=0.443N     P=0.570N     P=0.569     |P=0.268      P=0.514N     P=0.677      P=0.451      |
|COCH-ARM / FISHERS |     P=0.500      P=0.387N     P=0.590N     P=0.590N    |P=0.311      P=0.500N     P=0.691N     P=0.490      |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 47
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Stomach, Glandular                                                                                                               |
|     Necrosis                                                                                                                    |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     4/49 (8%)    9/49 (18%)   13/50 (26%)  13/50 (26%) |3/50 (6%)    6/50 (12%)   2/50 (4%)    4/49 (8%)    |
|POLY-3 ADJUSTED (b)|     10.8%        23.4%        30.4%        31.9%       |7.3%         14.7%        5.3%         11.2%        |
|TERMINAL (d)       |     1/13 (8%)    0/13 (0%)    0/15 (0%)    1/13 (8%)   |0/19 (0%)    0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     534          393          450          519         |506          497          603          418          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.096      P=0.109      P=0.034 *    P=0.020 *   |P=0.494      P=0.230      P=0.520N     P=0.421      |
|POLY 3             |     P=0.113      P=0.121      P=0.028 *    P=0.020 *   |P=0.515      P=0.237      P=0.535N     P=0.424      |
|POLY 1.5           |     P=0.105      P=0.116      P=0.022 *    P=0.018 *   |P=0.538      P=0.240      P=0.524N     P=0.448      |
|POLY 6             |     P=0.132      P=0.133      P=0.042 *    P=0.027 *   |P=0.487      P=0.236      P=0.542N     P=0.397      |
|LOGISTIC REGRESSION|     P=0.124      P=0.153      P=0.015 *    P=0.025 *   |P=0.569N     P=0.252      P=0.448N     P=0.587      |
|COCH-ARM / FISHERS |     P=0.100      P=0.116      P=0.017 *    P=0.017 *   |P=0.576      P=0.243      P=0.500N     P=0.489      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Testes                                                                                                                           |
|     Atrophy                                                                                                                     |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     1/50 (2%)    2/50 (4%)    5/50 (10%)   5/50 (10%)  |                                                    |
|POLY-3 ADJUSTED (b)|     2.7%         5.7%         12.8%        13.7%       |                                                    |
|TERMINAL (d)       |     1/13 (8%)    1/13 (8%)    1/15 (7%)    0/13 (0%)   |                                                    |
|FIRST INCIDENCE    |     733 (T)      306          394          614         |                                                    |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.144      P=0.498      P=0.130      P=0.094     |                                                    |
|POLY 3             |     P=0.156      P=0.484      P=0.113      P=0.096     |                                                    |
|POLY 1.5           |     P=0.156      P=0.489      P=0.108      P=0.097     |                                                    |
|POLY 6             |     P=0.165      P=0.482      P=0.123      P=0.100     |                                                    |
|LOGISTIC REGRESSION|     P=0.163      P=0.550      P=0.102      P=0.096     |                                                    |
|COCH-ARM / FISHERS |     P=0.158      P=0.500      P=0.102      P=0.102     |                                                    |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 48
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Testes: Artery                                                                                                                   |
|     Inflammation Chronic                                                                                                        |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     3/50 (6%)    4/50 (8%)    5/50 (10%)   4/50 (8%)   |                                                    |
|POLY-3 ADJUSTED (b)|     8.0%         11.4%        12.9%        11.0%       |                                                    |
|TERMINAL (d)       |     1/13 (8%)    1/13 (8%)    0/15 (0%)    0/13 (0%)   |                                                    |
|FIRST INCIDENCE    |     544          594          562          557         |                                                    |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.531      P=0.458      P=0.402      P=0.454     |                                                    |
|POLY 3             |     P=0.573      P=0.463      P=0.372      P=0.479     |                                                    |
|POLY 1.5           |     P=0.579      P=0.473      P=0.364      P=0.486     |                                                    |
|POLY 6             |     P=0.570      P=0.459      P=0.389      P=0.478     |                                                    |
|LOGISTIC REGRESSION|     P=0.585      P=0.492      P=0.354      P=0.516     |                                                    |
|COCH-ARM / FISHERS |     P=0.586      P=0.500      P=0.357      P=0.500     |                                                    |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Testes: Interstitial Cell                                                                                                        |
|     Hyperplasia                                                                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     2/50 (4%)    3/50 (6%)    2/50 (4%)    6/50 (12%)  |                                                    |
|POLY-3 ADJUSTED (b)|     5.3%         8.3%         5.1%         15.6%       |                                                    |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    0/13 (0%)   |                                                    |
|FIRST INCIDENCE    |     566          393          443          422         |                                                    |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.068      P=0.468      P=0.688N     P=0.129     |                                                    |
|POLY 3             |     P=0.070      P=0.482      P=0.682N     P=0.136     |                                                    |
|POLY 1.5           |     P=0.069      P=0.486      P=0.687N     P=0.134     |                                                    |
|POLY 6             |     P=0.073      P=0.481      P=0.677N     P=0.142     |                                                    |
|LOGISTIC REGRESSION|     P=0.066      P=0.663      P=0.697      P=0.196     |                                                    |
|COCH-ARM / FISHERS |     P=0.068      P=0.500      P=0.691N     P=0.134     |                                                    |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 49
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Thyroid Gland: C-Cell                                                                                                            |
|     Hyperplasia                                                                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     26/46 (57%)  28/46 (61%)  33/49 (67%)  29/50 (58%) |41/50 (82%)  41/49 (84%)  38/48 (79%)  33/49 (67%)  |
|POLY-3 ADJUSTED (b)|     65.1%        70.5%        75.7%        66.0%       |87.2%        87.0%        86.0%        76.1%        |
|TERMINAL (d)       |     9/13 (69%)   10/13 (77%)  13/15 (87%)  8/13 (62%)  |18/19 (95%)  13/17 (77%)  19/21 (91%)  7/11 (64%)   |
|FIRST INCIDENCE    |     338          524          443          310         |497          478          339          418          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.413      P=0.357      P=0.312      P=0.314     |P=0.331      P=0.409      P=0.377N     P=0.349      |
|POLY 3             |     P=0.371N     P=0.383      P=0.184      P=0.561     |P=0.062N     P=0.616N     P=0.563N     P=0.121N     |
|POLY 1.5           |     P=0.389N     P=0.379      P=0.181      P=0.538     |P=0.045N*    P=0.588      P=0.525N     P=0.102N     |
|POLY 6             |     P=0.336N     P=0.404      P=0.201      P=0.603N    |P=0.083N     P=0.548N     P=0.618N     P=0.136N     |
|LOGISTIC REGRESSION|     P=0.469N     P=0.372      P=0.202      P=0.515     |P=0.058N     P=0.500      P=0.555N     P=0.139N     |
|COCH-ARM / FISHERS |     P=0.418N     P=0.416      P=0.191      P=0.524     |P=0.026N*    P=0.518      P=0.460N     P=0.074N     |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Tooth                                                                                                                            |
|     Developmental Malformation                                                                                                  |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     2/2 (100%)   1/1 (100%)   0/0 (0%)     3/3 (100%)  |0/1 (0%)     0/0 (0%)     1/1 (100%)   0/0 (0%)     |
|POLY-3 ADJUSTED (b)|     100.0%       100.0%       0.0%         100.0%      |0.0%         0.0%         100.0%       0.0%         |
|TERMINAL (d)       |     1/1 (100%)   0/0 (0%)     0/0 (0%)     0/0 (0%)    |0/1 (0%)     0/0 (0%)     1/1 (100%)   0/0 (0%)     |
|FIRST INCIDENCE    |     590          647          ---          310         |---          ---          734 (T)      ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     (e)          (e)          (e)          (e)         |P=1.000      (e)          P=0.500      (e)          |
|POLY 3             |     (e)          (e)          (e)          (e)         |(e)          (e)          P=1.000N     (e)          |
|POLY 1.5           |     (e)          (e)          (e)          (e)         |(e)          (e)          P=1.000      (e)          |
|POLY 6             |     (e)          (e)          (e)          (e)         |(e)          (e)          P=1.000N     (e)          |
|LOGISTIC REGRESSION|     (e)          (e)          (e)          (e)         |(e)          (e)          P=0.250      (e)          |
|COCH-ARM / FISHERS |     (e)          (e)          (e)          (e)         |P=1.000      (e)          P=0.500      (e)          |
|=================================================================================================================================|
       Date:  02/17/99                           EXPERIMENT: 05180 TEST: 06                                            Page 50
                     Statistical Analysis of Non-neoplastic Lesions in       Rats(FISCHER 344)  -                  GALLIUM ARSENIDE
                                         Terminal Sacrifice at 105 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Trachea                                                                                                                          |
|     Mineralization                                                                                                              |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     2/49 (4%)    0/50 (0%)    2/49 (4%)    3/50 (6%)   |0/50 (0%)    0/50 (0%)    0/50 (0%)    1/49 (2%)    |
|POLY-3 ADJUSTED (b)|     5.5%         0.0%         5.3%         8.5%        |0.0%         0.0%         0.0%         2.9%         |
|TERMINAL (d)       |     0/13 (0%)    0/13 (0%)    0/15 (0%)    0/13 (0%)   |0/19 (0%)    0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     647          ---          654          645         |---          ---          ---          712          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.192      P=0.275N     P=0.664N     P=0.440     |P=0.181      (e)          (e)          P=0.415      |
|POLY 3             |     P=0.232      P=0.251N     P=0.684N     P=0.486     |P=0.237      (e)          (e)          P=0.471      |
|POLY 1.5           |     P=0.234      P=0.245N     P=0.689N     P=0.494     |P=0.242      (e)          (e)          P=0.480      |
|POLY 6             |     P=0.229      P=0.258N     P=0.676N     P=0.478     |P=0.230      (e)          (e)          P=0.460      |
|LOGISTIC REGRESSION|     P=0.217      P=0.251N     P=0.689N     P=0.477     |P=0.217      (e)          (e)          P=0.450      |
|COCH-ARM / FISHERS |     P=0.234      P=0.242N     P=0.691N     P=0.510     |P=0.253      (e)          (e)          P=0.495      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      0.01         0.1          1.0         |CONTROL      0.01         0.1          1.0          |
|                   |                  MG/M3        MG/M3        MG/M3       |             MG/M3        MG/M3        MG/M3        |
|=================================================================================================================================|
|                                                                                                                                 |
|Urinary Bladder                                                                                                                  |
|     Hemorrhage                                                                                                                  |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|LESION RATES       |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/48 (0%)    2/50 (4%)    0/50 (0%)    0/50 (0%)   |0/50 (0%)    1/50 (2%)    0/50 (0%)    0/49 (0%)    |
|POLY-3 ADJUSTED (b)|     0.0%         5.7%         0.0%         0.0%        |0.0%         2.6%         0.0%         0.0%         |
|TERMINAL (d)       |     0/13 (0%)    1/13 (8%)    0/15 (0%)    0/13 (0%)   |0/19 (0%)    0/17 (0%)    0/21 (0%)    0/11 (0%)    |
|FIRST INCIDENCE    |     ---          204          ---          ---         |---          585          ---          ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.447N     P=0.240      (e)          (e)         |P=0.699N     P=0.486      (e)          (e)          |
|POLY 3             |     P=0.461N     P=0.234      (e)          (e)         |P=0.681N     P=0.497      (e)          (e)          |
|POLY 1.5           |     P=0.453N     P=0.239      (e)          (e)         |P=0.677N     P=0.498      (e)          (e)          |
|POLY 6             |     P=0.470N     P=0.230      (e)          (e)         |P=0.686N     P=0.496      (e)          (e)          |
|LOGISTIC REGRESSION|     P=0.457N     P=0.374      (e)          (e)         |P=0.648N     P=0.503      (e)          (e)          |
|COCH-ARM / FISHERS |     P=0.439N     P=0.258      (e)          (e)         |P=0.673N     P=0.500      (e)          (e)          |
|=================================================================================================================================|

(a)  Number of tumor-bearing animals /  number of animals examined at site.
(b)  Poly-3 adjusted lifetime tumor incidence.
(d)  Observed incidence at terminal kill.
(f)  Beneath the control incidence are the P-values associated with the trend 
test.  Beneath the dosed group incidence are the P-values corresponding to 
pairwise comparisons between the controls and that dosed group.  The life
table analysis regards tumors in animals dying prior to  terminal kill as
 being (directly or indirectly) the cause of death.
Logistic regression is an alternative
 method for analyzing the incidence of non-fatal tumors. The Cochran-Armitage
and Fishers exact tests compare directly the overall incidence rates
For all tests a negative trend is indicated by N
(e)  Value of Statistic cannot be computed.
(I)  Interim sacrifice
(T)  Terminal sacrifice
#   Tumor rates based on number of animals necropsied.
*   To the right of any statistical result, indicates significance at (P<=0.05).
**  To the right of any statistical result, indicates significance at (P<=0.01).