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TDMS Study 88070-04 Pathology Tables

NTP                                        STATISTICAL ANALYSIS OF PRIMARY TUMORS                              REPORT: PEIRPT08
LAB: Battelle Northwest                                        ISOBUTENE                                       DATE: 06/19/97

EXPERIMENT: 88070 TEST: 04                                                                                     TIME: 12:22:01
TEST TYPE:  CHRONIC                             CAGES FROM 0000 TO LAST CAGE                                   PAGE:
CONT: N01-ES-15313                              ROUTE: RESPIRATORY EXPOSURE WHOLE BODY                         NTP C#: C88070
PATHOLOGIST: MILLER, R.                                                                                        CAS: 115-11-0007
            

Mice(B6C3F1)
-----------------------------
FOR ALL DOSES THE TUMOR RATES IN THE FOLLOWING TISSUES/ORGANS ARE BASED ON NUMBER OF TISSUES EXAMINED.
IN OTHER TISSUES/ORGANS, RATES ARE BASED ON NUMBER OF ANIMALS NECROPSIED.

                                                 ----------------
                                                 Adrenal Gland
                                                 Adrenal Medulla
                                                 Bone Marrow
                                                 Brain
                                                 Clitoral Gland
                                                 Clitoral/Preputial Gland
                                                 Epididymis
                                                 Heart
                                                 Islets, Pancreatic
                                                 Kidney
                                                 Liver
                                                 Lung
                                                 Nose
                                                 Ovary
                                                 Pancreas
                                                 Parathyroid Gland
                                                 Pituitary Gland
                                                 Preputial Gland
                                                 Prostate
                                                 Salivary Glands
                                                 Spleen
                                                 Testes
                                                 Thymus
                                                 Thyroid Gland
                                                 Urinary Bladder
NTP                                        STATISTICAL ANALYSIS OF PRIMARY TUMORS                              REPORT: PEIRPT08   
LAB: Battelle Northwest                                        ISOBUTENE                                       DATE: 06/19/97     
EXPERIMENT: 88070 TEST: 04                                                                                     TIME: 12:22:01     
TEST TYPE:  CHRONIC                             CAGES FROM 0000 TO LAST CAGE                                   PAGE:              
CONT: N01-ES-15313                              ROUTE: RESPIRATORY EXPOSURE WHOLE BODY                         NTP C#: C88070     
PATHOLOGIST: MILLER, R.                                                                                        CAS: 115-11-0007   



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

Male Mice
------------
Organ                                 Morphology
-----                                 ----------
Lung                                   Alveolar/Bronchiolar Adenoma
All Organs                             Benign Tumors
===============================================================
       Date:  06/19/97                           EXPERIMENT: 88070 TEST: 04                                            Page 1
                     Statistical Analysis of Primary Tumors in Mice(B6C3F1)        -                ISOBUTENE
                                         Terminal Sacrifice at 104 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Adrenal Cortex                                                                                                                   |
|     Adenoma                                                                                                                     |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     2/49 (4%)    3/49 (6%)    1/50 (2%)    3/49 (6%)   |0/49 (0%)    2/50 (4%)    0/49 (0%)    1/50 (2%)    |
|POLY-3 ADJUSTED (b)|     4.9%         7.0%         2.5%         7.8%        |0.0%         4.6%         0.0%         2.2%         |
|TERMINAL (d)       |     2/28 (7%)    3/32 (9%)    1/27 (4%)    3/28 (11%)  |0/32 (0%)    2/31 (7%)    0/39 (0%)    1/33 (3%)    |
|FIRST INCIDENCE    |     733 (T)      733 (T)      733 (T)      733 (T)     |---          735 (T)      ---          735 (T)      |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.435      P=0.561      P=0.513N     P=0.500     |P=0.641      P=0.231      (e)          P=0.506      |
|POLY 3             |     P=0.432      P=0.520      P=0.511N     P=0.474     |P=0.649      P=0.242      (e)          P=0.515      |
|POLY 1.5           |     P=0.440      P=0.513      P=0.504N     P=0.481     |P=0.646      P=0.243      (e)          P=0.512      |
|POLY 6             |     P=0.427      P=0.528      P=0.519N     P=0.471     |P=0.649      P=0.237      (e)          P=0.517      |
|LOGISTIC REGRESSION|     P=0.435      P=0.561      P=0.513N     P=0.500     |(e)          P=0.231      (e)          P=0.506      |
|COCH-ARM / FISHERS |     P=0.461      P=0.500      P=0.492N     P=0.500     |P=0.637      P=0.253      (e)          P=0.505      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Adrenal Medulla                                                                                                                  |
|     Pheochromocytoma Benign                                                                                                     |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/49 (0%)    1/49 (2%)    1/50 (2%)    2/49 (4%)   |0/48 (0%)    1/49 (2%)    2/49 (4%)    2/49 (4%)    |
|POLY-3 ADJUSTED (b)|     0.0%         2.3%         2.5%         5.2%        |0.0%         2.3%         4.4%         4.4%         |
|TERMINAL (d)       |     0/28 (0%)    1/32 (3%)    1/27 (4%)    1/28 (4%)   |0/32 (0%)    0/31 (0%)    2/39 (5%)    2/33 (6%)    |
|FIRST INCIDENCE    |     ---          733 (T)      733 (T)      633         |---          639          735 (T)      735 (T)      |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.201      P=0.527      P=0.493      P=0.237     |P=0.275      P=0.505      P=0.283      P=0.245      |
|POLY 3             |     P=0.197      P=0.509      P=0.494      P=0.226     |P=0.292      P=0.509      P=0.257      P=0.255      |
|POLY 1.5           |     P=0.201      P=0.506      P=0.498      P=0.229     |P=0.285      P=0.508      P=0.252      P=0.251      |
|POLY 6             |     P=0.197      P=0.512      P=0.489      P=0.226     |P=0.299      P=0.507      P=0.263      P=0.258      |
|LOGISTIC REGRESSION|     P=0.194      P=0.527      P=0.493      P=0.231     |P=0.283      P=0.469      P=0.283      P=0.245      |
|COCH-ARM / FISHERS |     P=0.213      P=0.500      P=0.505      P=0.247     |P=0.270      P=0.505      P=0.253      P=0.253      |
|=================================================================================================================================|
       Date:  06/19/97                           EXPERIMENT: 88070 TEST: 04                                            Page 2
                     Statistical Analysis of Primary Tumors in Mice(B6C3F1)       -                ISOBUTENE
                                         Terminal Sacrifice at 104 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Adrenal Medulla                                                                                                                  |
|     Pheochromocytoma: Benign, Complex, Malignant, NOS                                                                           |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/49 (0%)    2/49 (4%)    1/50 (2%)    2/49 (4%)   |0/48 (0%)    1/49 (2%)    2/49 (4%)    3/49 (6%)    |
|POLY-3 ADJUSTED (b)|     0.0%         4.7%         2.5%         5.2%        |0.0%         2.3%         4.4%         6.7%         |
|TERMINAL (d)       |     0/28 (0%)    2/32 (6%)    1/27 (4%)    1/28 (4%)   |0/32 (0%)    0/31 (0%)    2/39 (5%)    3/33 (9%)    |
|FIRST INCIDENCE    |     ---          733 (T)      733 (T)      633         |---          639          735 (T)      735 (T)      |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.322      P=0.268      P=0.493      P=0.237     |P=0.106      P=0.505      P=0.283      P=0.126      |
|POLY 3             |     P=0.322      P=0.247      P=0.494      P=0.226     |P=0.116      P=0.509      P=0.257      P=0.133      |
|POLY 1.5           |     P=0.326      P=0.244      P=0.498      P=0.229     |P=0.112      P=0.508      P=0.252      P=0.130      |
|POLY 6             |     P=0.322      P=0.251      P=0.489      P=0.226     |P=0.120      P=0.507      P=0.263      P=0.136      |
|LOGISTIC REGRESSION|     P=0.313      P=0.268      P=0.493      P=0.231     |P=0.115      P=0.469      P=0.283      P=0.126      |
|COCH-ARM / FISHERS |     P=0.340      P=0.247      P=0.505      P=0.247     |P=0.105      P=0.505      P=0.253      P=0.125      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Harderian Gland                                                                                                                  |
|     Adenoma                                                                                                                     |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |     #            #            #            #           |#            #            #            #            |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     3/50 (6%)    3/50 (6%)    4/50 (8%)    2/50 (4%)   |1/50 (2%)    1/50 (2%)    1/50 (2%)    1/50 (2%)    |
|POLY-3 ADJUSTED (b)|     7.2%         6.9%         10.0%        5.1%        |2.4%         2.3%         2.2%         2.2%         |
|TERMINAL (d)       |     2/28 (7%)    3/32 (9%)    1/27 (4%)    2/28 (7%)   |0/32 (0%)    1/31 (3%)    1/39 (3%)    1/33 (3%)    |
|FIRST INCIDENCE    |     610          733 (T)      631          733 (T)     |723          735 (T)      735 (T)      735 (T)      |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.423N     P=0.607N     P=0.473      P=0.505N    |P=0.681N     P=0.753      P=0.723N     P=0.757N     |
|POLY 3             |     P=0.434N     P=0.643N     P=0.480      P=0.527N    |P=0.667N     P=0.757N     P=0.744N     P=0.744N     |
|POLY 1.5           |     P=0.421N     P=0.650N     P=0.487      P=0.520N    |P=0.672N     P=0.755N     P=0.749N     P=0.748N     |
|POLY 6             |     P=0.442N     P=0.638N     P=0.475      P=0.531N    |P=0.664N     P=0.761      P=0.740N     P=0.742N     |
|LOGISTIC REGRESSION|     P=0.425N     P=0.635N     P=0.487      P=0.522N    |P=0.659N     P=0.759      P=0.738N     P=0.743N     |
|COCH-ARM / FISHERS |     P=0.390N     P=0.661N     P=0.500      P=0.500N    |P=0.683      P=0.753N     P=0.753N     P=0.753N     |
|=================================================================================================================================|
       Date:  06/19/97                           EXPERIMENT: 88070 TEST: 04                                            Page 3
                     Statistical Analysis of Primary Tumors in Mice(B6C3F1)       -                ISOBUTENE
                                         Terminal Sacrifice at 104 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Harderian Gland                                                                                                                  |
|     Carcinoma                                                                                                                   |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |     #            #            #            #           |#            #            #            #            |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     1/50 (2%)    0/50 (0%)    0/50 (0%)    2/50 (4%)   |1/50 (2%)    1/50 (2%)    0/50 (0%)    1/50 (2%)    |
|POLY-3 ADJUSTED (b)|     2.4%         0.0%         0.0%         5.1%        |2.4%         2.3%         0.0%         2.2%         |
|TERMINAL (d)       |     1/28 (4%)    0/32 (0%)    0/27 (0%)    2/28 (7%)   |0/32 (0%)    1/31 (3%)    0/39 (0%)    0/33 (0%)    |
|FIRST INCIDENCE    |     733 (T)      ---          ---          733 (T)     |723          735 (T)      ---          715          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.164      P=0.473N     P=0.507N     P=0.500     |P=0.676      P=0.753      P=0.473N     P=0.751N     |
|POLY 3             |     P=0.161      P=0.490N     P=0.509N     P=0.483     |P=0.680      P=0.757N     P=0.486N     P=0.744N     |
|POLY 1.5           |     P=0.165      P=0.493N     P=0.505N     P=0.487     |P=0.675      P=0.755N     P=0.490N     P=0.748N     |
|POLY 6             |     P=0.158      P=0.485N     P=0.512N     P=0.482     |P=0.683      P=0.761      P=0.482N     P=0.741N     |
|LOGISTIC REGRESSION|     P=0.164      (e)          (e)          P=0.500     |P=0.686      P=0.759      P=0.482N     P=0.746N     |
|COCH-ARM / FISHERS |     P=0.175      P=0.500N     P=0.500N     P=0.500     |P=0.668      P=0.753N     P=0.500N     P=0.753N     |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Harderian Gland                                                                                                                  |
|     Carcinoma or Adenoma                                                                                                        |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |     #            #            #            #           |#            #            #            #            |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     4/50 (8%)    3/50 (6%)    4/50 (8%)    4/50 (8%)   |2/50 (4%)    2/50 (4%)    1/50 (2%)    2/50 (4%)    |
|POLY-3 ADJUSTED (b)|     9.6%         6.9%         10.0%        10.2%       |4.7%         4.6%         2.2%         4.4%         |
|TERMINAL (d)       |     3/28 (11%)   3/32 (9%)    1/27 (4%)    4/28 (14%)  |0/32 (0%)    2/31 (7%)    1/39 (3%)    1/33 (3%)    |
|FIRST INCIDENCE    |     610          733 (T)      631          733 (T)     |723          735 (T)      735 (T)      715          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.492      P=0.434N     P=0.613      P=0.641     |P=0.622      P=0.682      P=0.445N     P=0.682N     |
|POLY 3             |     P=0.477      P=0.477N     P=0.624      P=0.612     |P=0.635      P=0.688N     P=0.475N     P=0.667N     |
|POLY 1.5           |     P=0.492      P=0.485N     P=0.631      P=0.620     |P=0.628      P=0.686N     P=0.482N     P=0.674N     |
|POLY 6             |     P=0.466      P=0.470N     P=0.620      P=0.607     |P=0.641      P=0.694      P=0.469N     P=0.663N     |
|LOGISTIC REGRESSION|     P=0.483      P=0.463N     P=0.627      P=0.618     |P=0.635N     P=0.689      P=0.464N     P=0.665N     |
|COCH-ARM / FISHERS |     P=0.529      P=0.500N     P=0.643N     P=0.643N    |P=0.613      P=0.691N     P=0.500N     P=0.691N     |
|=================================================================================================================================|
       Date:  06/19/97                           EXPERIMENT: 88070 TEST: 04                                            Page 4
                     Statistical Analysis of Primary Tumors in Mice(B6C3F1)       -                ISOBUTENE
                                         Terminal Sacrifice at 104 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Kidney: Renal Tubule                                                                                                             |
|     Adenoma                                                                                                                     |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     1/50 (2%)    0/49 (0%)    2/50 (4%)    0/50 (0%)   |0/49 (0%)    0/50 (0%)    0/49 (0%)    0/50 (0%)    |
|POLY-3 ADJUSTED (b)|     2.4%         0.0%         5.1%         0.0%        |0.0%         0.0%         0.0%         0.0%         |
|TERMINAL (d)       |     1/28 (4%)    0/32 (0%)    2/27 (7%)    0/28 (0%)   |0/32 (0%)    0/31 (0%)    0/39 (0%)    0/33 (0%)    |
|FIRST INCIDENCE    |     733 (T)      ---          733 (T)      ---         |---          ---          ---          ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.451N     P=0.473N     P=0.487      P=0.500N    |(e)          (e)          (e)          (e)          |
|POLY 3             |     P=0.463N     P=0.494N     P=0.484      P=0.510N    |(e)          (e)          (e)          (e)          |
|POLY 1.5           |     P=0.455N     P=0.498N     P=0.491      P=0.507N    |(e)          (e)          (e)          (e)          |
|POLY 6             |     P=0.469N     P=0.489N     P=0.478      P=0.510N    |(e)          (e)          (e)          (e)          |
|LOGISTIC REGRESSION|     P=0.451N     (e)          P=0.487      (e)         |(e)          (e)          (e)          (e)          |
|COCH-ARM / FISHERS |     P=0.434N     P=0.505N     P=0.500      P=0.500N    |(e)          (e)          (e)          (e)          |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Liver                                                                                                                            |
|     Hemangiosarcoma                                                                                                             |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     1/50 (2%)    0/50 (0%)    2/50 (4%)    2/49 (4%)   |0/47 (0%)    0/50 (0%)    0/50 (0%)    0/50 (0%)    |
|POLY-3 ADJUSTED (b)|     2.4%         0.0%         5.0%         5.2%        |0.0%         0.0%         0.0%         0.0%         |
|TERMINAL (d)       |     0/28 (0%)    0/32 (0%)    1/27 (4%)    2/28 (7%)   |0/32 (0%)    0/31 (0%)    0/39 (0%)    0/33 (0%)    |
|FIRST INCIDENCE    |     664          ---          559          733 (T)     |---          ---          ---          ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.271      P=0.484N     P=0.472      P=0.497     |(e)          (e)          (e)          (e)          |
|POLY 3             |     P=0.252      P=0.491N     P=0.487      P=0.474     |(e)          (e)          (e)          (e)          |
|POLY 1.5           |     P=0.261      P=0.494N     P=0.492      P=0.478     |(e)          (e)          (e)          (e)          |
|POLY 6             |     P=0.247      P=0.488N     P=0.482      P=0.472     |(e)          (e)          (e)          (e)          |
|LOGISTIC REGRESSION|     P=0.273      P=0.510N     P=0.508      P=0.476     |(e)          (e)          (e)          (e)          |
|COCH-ARM / FISHERS |     P=0.284      P=0.500N     P=0.500      P=0.492     |(e)          (e)          (e)          (e)          |
|=================================================================================================================================|
       Date:  06/19/97                           EXPERIMENT: 88070 TEST: 04                                            Page 5
                     Statistical Analysis of Primary Tumors in Mice(B6C3F1)       -                ISOBUTENE
                                         Terminal Sacrifice at 104 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Liver                                                                                                                            |
|     Hepatoblastoma                                                                                                              |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/50 (0%)    0/50 (0%)    1/50 (2%)    0/49 (0%)   |0/47 (0%)    2/50 (4%)    0/50 (0%)    0/50 (0%)    |
|POLY-3 ADJUSTED (b)|     0.0%         0.0%         2.5%         0.0%        |0.0%         4.6%         0.0%         0.0%         |
|TERMINAL (d)       |     0/28 (0%)    0/32 (0%)    1/27 (4%)    0/28 (0%)   |0/32 (0%)    1/31 (3%)    0/39 (0%)    0/33 (0%)    |
|FIRST INCIDENCE    |     ---          ---          733 (T)      ---         |---          695          ---          ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.780N     (e)          P=0.493      (e)         |P=0.374N     P=0.233      (e)          (e)          |
|POLY 3             |     P=0.787N     (e)          P=0.491      (e)         |P=0.387N     P=0.244      (e)          (e)          |
|POLY 1.5           |     P=0.784N     (e)          P=0.495      (e)         |P=0.385N     P=0.247      (e)          (e)          |
|POLY 6             |     P=0.789N     (e)          P=0.488      (e)         |P=0.392N     P=0.239      (e)          (e)          |
|LOGISTIC REGRESSION|     (e)          (e)          P=0.493      (e)         |P=0.378N     P=0.242      (e)          (e)          |
|COCH-ARM / FISHERS |     P=0.776N     (e)          P=0.500      (e)         |P=0.384N     P=0.263      (e)          (e)          |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Liver                                                                                                                            |
|     Hepatocellular Adenoma                                                                                                      |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     20/50 (40%)  24/50 (48%)  18/50 (36%)  17/49 (35%) |20/47 (43%)  22/50 (44%)  19/50 (38%)  20/50 (40%)  |
|POLY-3 ADJUSTED (b)|     46.9%        51.8%        43.6%        42.6%       |46.3%        49.2%        40.8%        43.1%        |
|TERMINAL (d)       |     14/28 (50%)  17/32 (53%)  12/27 (44%)  13/28 (46%) |16/32 (50%)  17/31 (55%)  17/39 (44%)  16/33 (49%)  |
|FIRST INCIDENCE    |     592          522          584          330         |621          611          543          596          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.270N     P=0.466      P=0.504N     P=0.361N    |P=0.430N     P=0.370      P=0.234N     P=0.517N     |
|POLY 3             |     P=0.299N     P=0.400      P=0.468N     P=0.432N    |P=0.389N     P=0.474      P=0.379N     P=0.462N     |
|POLY 1.5           |     P=0.263N     P=0.348      P=0.448N     P=0.412N    |P=0.404N     P=0.497      P=0.389N     P=0.467N     |
|POLY 6             |     P=0.340N     P=0.459      P=0.483N     P=0.451N    |P=0.377N     P=0.442      P=0.364N     P=0.461N     |
|LOGISTIC REGRESSION|     P=0.289N     P=0.338      P=0.506N     P=0.440N    |P=0.349N     P=0.429      P=0.365N     P=0.438N     |
|COCH-ARM / FISHERS |     P=0.203N     P=0.273      P=0.418N     P=0.368N    |P=0.431N     P=0.525      P=0.401N     P=0.480N     |
|=================================================================================================================================|
       Date:  06/19/97                           EXPERIMENT: 88070 TEST: 04                                            Page 6
                     Statistical Analysis of Primary Tumors in Mice(B6C3F1)       -                ISOBUTENE
                                         Terminal Sacrifice at 104 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Liver                                                                                                                            |
|     Hepatocellular Carcinoma                                                                                                    |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     13/50 (26%)  13/50 (26%)  14/50 (28%)  14/49 (29%) |5/47 (11%)   8/50 (16%)   7/50 (14%)   11/50 (22%)  |
|POLY-3 ADJUSTED (b)|     28.6%        27.4%        31.9%        31.7%       |11.7%        17.7%        15.0%        22.9%        |
|TERMINAL (d)       |     2/28 (7%)    4/32 (13%)   5/27 (19%)   4/28 (14%)  |4/32 (13%)   3/31 (10%)   5/39 (13%)   4/33 (12%)   |
|FIRST INCIDENCE    |     399          405          389          330         |610          567          600          527          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.382      P=0.498N     P=0.433      P=0.450     |P=0.125      P=0.283      P=0.499      P=0.122      |
|POLY 3             |     P=0.401      P=0.541N     P=0.453      P=0.464     |P=0.133      P=0.315      P=0.442      P=0.132      |
|POLY 1.5           |     P=0.405      P=0.557N     P=0.472      P=0.462     |P=0.122      P=0.316      P=0.433      P=0.121      |
|POLY 6             |     P=0.405      P=0.530N     P=0.433      P=0.472     |P=0.148      P=0.315      P=0.457      P=0.146      |
|LOGISTIC REGRESSION|     P=0.491N     P=0.440      P=0.570      P=0.587N    |P=0.076      P=0.342      P=0.421      P=0.086      |
|COCH-ARM / FISHERS |     P=0.436      P=0.590N     P=0.500      P=0.475     |P=0.106      P=0.318      P=0.424      P=0.108      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Liver                                                                                                                            |
|     Hepatocellular Carcinoma or Hepatoblastoma                                                                                  |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     13/50 (26%)  13/50 (26%)  14/50 (28%)  14/49 (29%) |5/47 (11%)   10/50 (20%)  7/50 (14%)   11/50 (22%)  |
|POLY-3 ADJUSTED (b)|     28.6%        27.4%        31.9%        31.7%       |11.7%        22.0%        15.0%        22.9%        |
|TERMINAL (d)       |     2/28 (7%)    4/32 (13%)   5/27 (19%)   4/28 (14%)  |4/32 (13%)   4/31 (13%)   5/39 (13%)   4/33 (12%)   |
|FIRST INCIDENCE    |     399          405          389          330         |610          567          600          527          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.382      P=0.498N     P=0.433      P=0.450     |P=0.193      P=0.141      P=0.499      P=0.122      |
|POLY 3             |     P=0.401      P=0.541N     P=0.453      P=0.464     |P=0.206      P=0.158      P=0.442      P=0.132      |
|POLY 1.5           |     P=0.405      P=0.557N     P=0.472      P=0.462     |P=0.190      P=0.159      P=0.433      P=0.121      |
|POLY 6             |     P=0.405      P=0.530N     P=0.433      P=0.472     |P=0.226      P=0.159      P=0.457      P=0.146      |
|LOGISTIC REGRESSION|     P=0.491N     P=0.440      P=0.570      P=0.587N    |P=0.130      P=0.174      P=0.421      P=0.086      |
|COCH-ARM / FISHERS |     P=0.436      P=0.590N     P=0.500      P=0.475     |P=0.169      P=0.160      P=0.424      P=0.108      |
|=================================================================================================================================|
       Date:  06/19/97                           EXPERIMENT: 88070 TEST: 04                                            Page 7
                     Statistical Analysis of Primary Tumors in Mice(B6C3F1)       -                ISOBUTENE
                                         Terminal Sacrifice at 104 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Liver                                                                                                                            |
|     Hepatocellular Carcinoma or Hepatocellular Adenoma                                                                          |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     30/50 (60%)  32/50 (64%)  28/50 (56%)  29/49 (59%) |23/47 (49%)  28/50 (56%)  22/50 (44%)  28/50 (56%)  |
|POLY-3 ADJUSTED (b)|     64.2%        65.7%        62.4%        64.9%       |52.7%        60.0%        46.4%        58.1%        |
|TERMINAL (d)       |     15/28 (54%)  19/32 (59%)  15/27 (56%)  16/28 (57%) |18/32 (56%)  18/31 (58%)  18/39 (46%)  19/33 (58%)  |
|FIRST INCIDENCE    |     399          405          389          330         |610          567          543          527          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.517      P=0.489N     P=0.541N     P=0.550N    |P=0.356      P=0.203      P=0.224N     P=0.300      |
|POLY 3             |     P=0.549      P=0.528      P=0.516N     P=0.563     |P=0.399      P=0.309      P=0.348N     P=0.377      |
|POLY 1.5           |     P=0.540N     P=0.492      P=0.476N     P=0.573     |P=0.372      P=0.309      P=0.366N     P=0.350      |
|POLY 6             |     P=0.533      P=0.552      P=0.558N     P=0.555     |P=0.426      P=0.316      P=0.323N     P=0.408      |
|LOGISTIC REGRESSION|     P=0.462N     P=0.386      P=0.433N     P=0.556N    |P=0.359      P=0.269      P=0.369N     P=0.330      |
|COCH-ARM / FISHERS |     P=0.461N     P=0.418      P=0.420N     P=0.548N    |P=0.330      P=0.311      P=0.388N     P=0.311      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Liver                                                                                                                            |
|     Hepatocellular Carcinoma, Hepatocellular Adenoma,                                                                           |
|     or Hepatoblastoma                                                                                                           |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     30/50 (60%)  32/50 (64%)  28/50 (56%)  29/49 (59%) |23/47 (49%)  28/50 (56%)  22/50 (44%)  28/50 (56%)  |
|POLY-3 ADJUSTED (b)|     64.2%        65.7%        62.4%        64.9%       |52.7%        60.0%        46.4%        58.1%        |
|TERMINAL (d)       |     15/28 (54%)  19/32 (59%)  15/27 (56%)  16/28 (57%) |18/32 (56%)  18/31 (58%)  18/39 (46%)  19/33 (58%)  |
|FIRST INCIDENCE    |     399          405          389          330         |610          567          543          527          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.517      P=0.489N     P=0.541N     P=0.550N    |P=0.356      P=0.203      P=0.224N     P=0.300      |
|POLY 3             |     P=0.549      P=0.528      P=0.516N     P=0.563     |P=0.399      P=0.309      P=0.348N     P=0.377      |
|POLY 1.5           |     P=0.540N     P=0.492      P=0.476N     P=0.573     |P=0.372      P=0.309      P=0.366N     P=0.350      |
|POLY 6             |     P=0.533      P=0.552      P=0.558N     P=0.555     |P=0.426      P=0.316      P=0.323N     P=0.408      |
|LOGISTIC REGRESSION|     P=0.462N     P=0.386      P=0.433N     P=0.556N    |P=0.359      P=0.269      P=0.369N     P=0.330      |
|COCH-ARM / FISHERS |     P=0.461N     P=0.418      P=0.420N     P=0.548N    |P=0.330      P=0.311      P=0.388N     P=0.311      |
|=================================================================================================================================|
       Date:  06/19/97                           EXPERIMENT: 88070 TEST: 04                                            Page 8
                     Statistical Analysis of Primary Tumors in Mice(B6C3F1)       -                ISOBUTENE
                                         Terminal Sacrifice at 104 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Lung                                                                                                                             |
|     Alveolar/Bronchiolar Adenoma                                                                                                |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     12/50 (24%)  7/50 (14%)   5/50 (10%)   3/50 (6%)   |2/49 (4%)    2/50 (4%)    2/50 (4%)    2/50 (4%)    |
|POLY-3 ADJUSTED (b)|     28.7%        16.1%        12.5%        7.6%        |4.7%         4.6%         4.4%         4.4%         |
|TERMINAL (d)       |     9/28 (32%)   6/32 (19%)   4/27 (15%)   3/28 (11%)  |1/32 (3%)    1/31 (3%)    2/39 (5%)    1/33 (3%)    |
|FIRST INCIDENCE    |     592          698          583          733 (T)     |653          639          735 (T)      701          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.031N*    P=0.091N     P=0.068N     P=0.013N*   |P=0.607N     P=0.684      P=0.633N     P=0.667N     |
|POLY 3             |     P=0.031N*    P=0.125N     P=0.060N     P=0.013N*   |P=0.609N     P=0.686N     P=0.670N     P=0.668N     |
|POLY 1.5           |     P=0.028N*    P=0.135N     P=0.057N     P=0.013N*   |P=0.615N     P=0.684N     P=0.675N     P=0.673N     |
|POLY 6             |     P=0.032N*    P=0.116N     P=0.064N     P=0.013N*   |P=0.604N     P=0.693N     P=0.664N     P=0.666N     |
|LOGISTIC REGRESSION|     P=0.032N*    P=0.106N     P=0.067N     P=0.014N*   |P=0.617N     P=0.689N     P=0.672N     P=0.681N     |
|COCH-ARM / FISHERS |     P=0.024N*    P=0.154N     P=0.054N     P=0.011N*   |P=0.628N     P=0.684N     P=0.684N     P=0.684N     |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Lung                                                                                                                             |
|     Alveolar/Bronchiolar Carcinoma                                                                                              |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     6/50 (12%)   6/50 (12%)   4/50 (8%)    6/50 (12%)  |4/49 (8%)    2/50 (4%)    2/50 (4%)    1/50 (2%)    |
|POLY-3 ADJUSTED (b)|     14.2%        13.8%        10.1%        15.3%       |9.3%         4.6%         4.4%         2.2%         |
|TERMINAL (d)       |     4/28 (14%)   6/32 (19%)   4/27 (15%)   6/28 (21%)  |1/32 (3%)    1/31 (3%)    2/39 (5%)    1/33 (3%)    |
|FIRST INCIDENCE    |     580          733 (T)      733 (T)      733 (T)     |639          639          735 (T)      735 (T)      |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.504      P=0.537N     P=0.397N     P=0.612     |P=0.192N     P=0.355N     P=0.279N     P=0.165N     |
|POLY 3             |     P=0.490      P=0.601N     P=0.411N     P=0.571     |P=0.193N     P=0.331N     P=0.311N     P=0.161N     |
|POLY 1.5           |     P=0.508      P=0.606N     P=0.394N     P=0.586     |P=0.197N     P=0.326N     P=0.316N     P=0.164N     |
|POLY 6             |     P=0.477      P=0.597N     P=0.432N     P=0.559     |P=0.189N     P=0.343N     P=0.307N     P=0.161N     |
|LOGISTIC REGRESSION|     P=0.489      P=0.581N     P=0.400N     P=0.588     |P=0.200N     P=0.330N     P=0.321N     P=0.174N     |
|COCH-ARM / FISHERS |     P=0.549      P=0.620N     P=0.370N     P=0.620N    |P=0.204N     P=0.329N     P=0.329N     P=0.175N     |
|=================================================================================================================================|
       Date:  06/19/97                           EXPERIMENT: 88070 TEST: 04                                            Page 9
                     Statistical Analysis of Primary Tumors in Mice(B6C3F1)       -                ISOBUTENE
                                         Terminal Sacrifice at 104 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Lung                                                                                                                             |
|     Alveolar/Bronchiolar Carcinoma or Alveolar/Bronchiolar                                                                      |
|     Adenoma                                                                                                                     |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     17/50 (34%)  13/50 (26%)  9/50 (18%)   9/50 (18%)  |6/49 (12%)   4/50 (8%)    4/50 (8%)    3/50 (6%)    |
|POLY-3 ADJUSTED (b)|     39.7%        29.8%        22.5%        22.9%       |13.8%        9.1%         8.8%         6.5%         |
|TERMINAL (d)       |     12/28 (43%)  12/32 (38%)  8/27 (30%)   9/28 (32%)  |2/32 (6%)    2/31 (7%)    4/39 (10%)   2/33 (6%)    |
|FIRST INCIDENCE    |     580          698          583          733 (T)     |639          639          735 (T)      701          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.107N     P=0.141N     P=0.070N     P=0.056N    |P=0.246N     P=0.391N     P=0.285N     P=0.218N     |
|POLY 3             |     P=0.119N     P=0.227N     P=0.070N     P=0.077N    |P=0.248N     P=0.360N     P=0.338N     P=0.215N     |
|POLY 1.5           |     P=0.107N     P=0.235N     P=0.062N     P=0.068N    |P=0.254N     P=0.354N     P=0.342N     P=0.219N     |
|POLY 6             |     P=0.130N     P=0.225N     P=0.081N     P=0.086N    |P=0.244N     P=0.376N     P=0.336N     P=0.217N     |
|LOGISTIC REGRESSION|     P=0.116N     P=0.180N     P=0.069N     P=0.066N    |P=0.257N     P=0.359N     P=0.340N     P=0.229N     |
|COCH-ARM / FISHERS |     P=0.084N     P=0.257N     P=0.055N     P=0.055N    |P=0.266N     P=0.357N     P=0.357N     P=0.233N     |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Mammary Gland                                                                                                                    |
|     Carcinoma                                                                                                                   |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |     #            #            #            #           |#            #            #            #            |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/50 (0%)    0/50 (0%)    0/50 (0%)    0/50 (0%)   |2/50 (4%)    0/50 (0%)    2/50 (4%)    0/50 (0%)    |
|POLY-3 ADJUSTED (b)|     0.0%         0.0%         0.0%         0.0%        |4.6%         0.0%         4.4%         0.0%         |
|TERMINAL (d)       |     0/28 (0%)    0/32 (0%)    0/27 (0%)    0/28 (0%)   |0/32 (0%)    0/31 (0%)    2/39 (5%)    0/33 (0%)    |
|FIRST INCIDENCE    |     ---          ---          ---          ---         |541          ---          735 (T)      ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     (e)          (e)          (e)          (e)         |P=0.278N     P=0.245N     P=0.643N     P=0.224N     |
|POLY 3             |     (e)          (e)          (e)          (e)         |P=0.274N     P=0.236N     P=0.673N     P=0.224N     |
|POLY 1.5           |     (e)          (e)          (e)          (e)         |P=0.280N     P=0.234N     P=0.678N     P=0.227N     |
|POLY 6             |     (e)          (e)          (e)          (e)         |P=0.267N     P=0.242N     P=0.669N     P=0.224N     |
|LOGISTIC REGRESSION|     (e)          (e)          (e)          (e)         |P=0.306N     P=0.270N     P=0.680      P=0.294N     |
|COCH-ARM / FISHERS |     (e)          (e)          (e)          (e)         |P=0.290N     P=0.247N     P=0.691N     P=0.247N     |
|=================================================================================================================================|
       Date:  06/19/97                           EXPERIMENT: 88070 TEST: 04                                            Page 10
                     Statistical Analysis of Primary Tumors in Mice(B6C3F1)       -                ISOBUTENE
                                         Terminal Sacrifice at 104 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Ovary                                                                                                                            |
|     Cystadenoma                                                                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |                                                        |0/48 (0%)    3/50 (6%)    1/48 (2%)    2/50 (4%)    |
|POLY-3 ADJUSTED (b)|                                                        |0.0%         6.8%         2.3%         4.4%         |
|TERMINAL (d)       |                                                        |0/32 (0%)    1/31 (3%)    1/38 (3%)    2/33 (6%)    |
|FIRST INCIDENCE    |                                                        |---          572          735 (T)      735 (T)      |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |                                                        |P=0.471      P=0.127      P=0.534      P=0.245      |
|POLY 3             |                                                        |P=0.486      P=0.125      P=0.509      P=0.255      |
|POLY 1.5           |                                                        |P=0.482      P=0.126      P=0.506      P=0.252      |
|POLY 6             |                                                        |P=0.488      P=0.122      P=0.514      P=0.257      |
|LOGISTIC REGRESSION|                                                        |P=0.476      P=0.126      P=0.534      P=0.245      |
|COCH-ARM / FISHERS |                                                        |P=0.472      P=0.129      P=0.500      P=0.258      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Ovary                                                                                                                            |
|     Granulosa Cell Tumor Benign                                                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |                                                        |1/48 (2%)    2/50 (4%)    0/48 (0%)    0/50 (0%)    |
|POLY-3 ADJUSTED (b)|                                                        |2.4%         4.6%         0.0%         0.0%         |
|TERMINAL (d)       |                                                        |1/32 (3%)    2/31 (7%)    0/38 (0%)    0/33 (0%)    |
|FIRST INCIDENCE    |                                                        |735 (T)      735 (T)      ---          ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |                                                        |P=0.232N     P=0.489      P=0.466N     P=0.494N     |
|POLY 3             |                                                        |P=0.234N     P=0.509      P=0.491N     P=0.484N     |
|POLY 1.5           |                                                        |P=0.234N     P=0.513      P=0.494N     P=0.487N     |
|POLY 6             |                                                        |P=0.236N     P=0.501      P=0.486N     P=0.483N     |
|LOGISTIC REGRESSION|                                                        |P=0.232N     P=0.489      (e)          (e)          |
|COCH-ARM / FISHERS |                                                        |P=0.236N     P=0.515      P=0.500N     P=0.490N     |
|=================================================================================================================================|
       Date:  06/19/97                           EXPERIMENT: 88070 TEST: 04                                            Page 11
                     Statistical Analysis of Primary Tumors in Mice(B6C3F1)       -                ISOBUTENE
                                         Terminal Sacrifice at 104 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Pituitary Gland: Pars Distalis or Unspecified Site                                                                               |
|     Adenoma                                                                                                                     |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/50 (0%)    0/48 (0%)    0/49 (0%)    0/48 (0%)   |8/49 (16%)   13/49 (27%)  12/49 (24%)  12/49 (24%)  |
|POLY-3 ADJUSTED (b)|     0.0%         0.0%         0.0%         0.0%        |18.8%        29.8%        26.7%        26.2%        |
|TERMINAL (d)       |     0/28 (0%)    0/32 (0%)    0/27 (0%)    0/28 (0%)   |6/32 (19%)   10/31 (32%)  11/39 (28%)  8/33 (24%)   |
|FIRST INCIDENCE    |     ---          ---          ---          ---         |709          615          709          672          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     (e)          (e)          (e)          (e)         |P=0.435      P=0.147      P=0.385      P=0.275      |
|POLY 3             |     (e)          (e)          (e)          (e)         |P=0.462      P=0.171      P=0.265      P=0.279      |
|POLY 1.5           |     (e)          (e)          (e)          (e)         |P=0.435      P=0.171      P=0.252      P=0.261      |
|POLY 6             |     (e)          (e)          (e)          (e)         |P=0.492      P=0.166      P=0.281      P=0.298      |
|LOGISTIC REGRESSION|     (e)          (e)          (e)          (e)         |P=0.479      P=0.153      P=0.312      P=0.286      |
|COCH-ARM / FISHERS |     (e)          (e)          (e)          (e)         |P=0.387      P=0.162      P=0.226      P=0.226      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Pituitary Gland: Pars Distalis or Unspecified Site                                                                               |
|     Carcinoma or Adenoma                                                                                                        |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/50 (0%)    0/48 (0%)    0/49 (0%)    0/48 (0%)   |8/49 (16%)   13/49 (27%)  13/49 (27%)  12/49 (24%)  |
|POLY-3 ADJUSTED (b)|     0.0%         0.0%         0.0%         0.0%        |18.8%        29.8%        28.4%        26.2%        |
|TERMINAL (d)       |     0/28 (0%)    0/32 (0%)    0/27 (0%)    0/28 (0%)   |6/32 (19%)   10/31 (32%)  11/39 (28%)  8/33 (24%)   |
|FIRST INCIDENCE    |     ---          ---          ---          ---         |709          615          477          672          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     (e)          (e)          (e)          (e)         |P=0.450      P=0.147      P=0.303      P=0.275      |
|POLY 3             |     (e)          (e)          (e)          (e)         |P=0.476      P=0.171      P=0.206      P=0.279      |
|POLY 1.5           |     (e)          (e)          (e)          (e)         |P=0.449      P=0.171      P=0.191      P=0.261      |
|POLY 6             |     (e)          (e)          (e)          (e)         |P=0.506      P=0.166      P=0.224      P=0.298      |
|LOGISTIC REGRESSION|     (e)          (e)          (e)          (e)         |P=0.475      P=0.153      P=0.199      P=0.286      |
|COCH-ARM / FISHERS |     (e)          (e)          (e)          (e)         |P=0.401      P=0.162      P=0.162      P=0.226      |
|=================================================================================================================================|
       Date:  06/19/97                           EXPERIMENT: 88070 TEST: 04                                            Page 12
                     Statistical Analysis of Primary Tumors in Mice(B6C3F1)       -                ISOBUTENE
                                         Terminal Sacrifice at 104 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Skin                                                                                                                             |
|     Fibroma, Fibrosarcoma, Sarcoma, Myxoma, Myxosarcoma,                                                                        |
|     or Fibrous Histiocytoma                                                                                                     |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |     #            #            #            #           |#            #            #            #            |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/50 (0%)    0/50 (0%)    1/50 (2%)    1/50 (2%)   |2/50 (4%)    5/50 (10%)   1/50 (2%)    3/50 (6%)    |
|POLY-3 ADJUSTED (b)|     0.0%         0.0%         2.5%         2.5%        |4.7%         11.3%        2.2%         6.5%         |
|TERMINAL (d)       |     0/28 (0%)    0/32 (0%)    0/27 (0%)    0/28 (0%)   |0/32 (0%)    3/31 (10%)   0/39 (0%)    1/33 (3%)    |
|FIRST INCIDENCE    |     ---          ---          512          508         |667          611          692          709          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.330      (e)          P=0.496      P=0.491     |P=0.570N     P=0.217      P=0.458N     P=0.524      |
|POLY 3             |     P=0.330      (e)          P=0.494      P=0.494     |P=0.578N     P=0.228      P=0.476N     P=0.532      |
|POLY 1.5           |     P=0.334      (e)          P=0.497      P=0.494     |P=0.583N     P=0.228      P=0.482N     P=0.524      |
|POLY 6             |     P=0.328      (e)          P=0.493      P=0.495     |P=0.576N     P=0.223      P=0.469N     P=0.536      |
|LOGISTIC REGRESSION|     P=0.515      (e)          P=0.532      P=0.589     |P=0.597N     P=0.219      P=0.501N     P=0.528      |
|COCH-ARM / FISHERS |     P=0.348      (e)          P=0.500      P=0.500     |P=0.601N     P=0.218      P=0.500N     P=0.500      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Skin                                                                                                                             |
|     Fibrosarcoma                                                                                                                |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |     #            #            #            #           |#            #            #            #            |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/50 (0%)    0/50 (0%)    0/50 (0%)    0/50 (0%)   |0/50 (0%)    2/50 (4%)    1/50 (2%)    1/50 (2%)    |
|POLY-3 ADJUSTED (b)|     0.0%         0.0%         0.0%         0.0%        |0.0%         4.6%         2.2%         2.2%         |
|TERMINAL (d)       |     0/28 (0%)    0/32 (0%)    0/27 (0%)    0/28 (0%)   |0/32 (0%)    2/31 (7%)    0/39 (0%)    0/33 (0%)    |
|FIRST INCIDENCE    |     ---          ---          ---          ---         |---          735 (T)      692          729          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     (e)          (e)          (e)          (e)         |P=0.669      P=0.231      P=0.526      P=0.512      |
|POLY 3             |     (e)          (e)          (e)          (e)         |P=0.678      P=0.242      P=0.515      P=0.515      |
|POLY 1.5           |     (e)          (e)          (e)          (e)         |P=0.672      P=0.243      P=0.511      P=0.511      |
|POLY 6             |     (e)          (e)          (e)          (e)         |P=0.682      P=0.237      P=0.520      P=0.517      |
|LOGISTIC REGRESSION|     (e)          (e)          (e)          (e)         |P=0.675      P=0.231      P=0.498      P=0.518      |
|COCH-ARM / FISHERS |     (e)          (e)          (e)          (e)         |P=0.654      P=0.247      P=0.500      P=0.500      |
|=================================================================================================================================|
       Date:  06/19/97                           EXPERIMENT: 88070 TEST: 04                                            Page 13
                     Statistical Analysis of Primary Tumors in Mice(B6C3F1)       -                ISOBUTENE
                                         Terminal Sacrifice at 104 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Skin                                                                                                                             |
|     Fibrosarcoma, Sarcoma, Myxosarcoma, or Fibrous Histiocytoma                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |     #            #            #            #           |#            #            #            #            |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/50 (0%)    0/50 (0%)    1/50 (2%)    1/50 (2%)   |2/50 (4%)    5/50 (10%)   1/50 (2%)    3/50 (6%)    |
|POLY-3 ADJUSTED (b)|     0.0%         0.0%         2.5%         2.5%        |4.7%         11.3%        2.2%         6.5%         |
|TERMINAL (d)       |     0/28 (0%)    0/32 (0%)    0/27 (0%)    0/28 (0%)   |0/32 (0%)    3/31 (10%)   0/39 (0%)    1/33 (3%)    |
|FIRST INCIDENCE    |     ---          ---          512          508         |667          611          692          709          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.330      (e)          P=0.496      P=0.491     |P=0.570N     P=0.217      P=0.458N     P=0.524      |
|POLY 3             |     P=0.330      (e)          P=0.494      P=0.494     |P=0.578N     P=0.228      P=0.476N     P=0.532      |
|POLY 1.5           |     P=0.334      (e)          P=0.497      P=0.494     |P=0.583N     P=0.228      P=0.482N     P=0.524      |
|POLY 6             |     P=0.328      (e)          P=0.493      P=0.495     |P=0.576N     P=0.223      P=0.469N     P=0.536      |
|LOGISTIC REGRESSION|     P=0.515      (e)          P=0.532      P=0.589     |P=0.597N     P=0.219      P=0.501N     P=0.528      |
|COCH-ARM / FISHERS |     P=0.348      (e)          P=0.500      P=0.500     |P=0.601N     P=0.218      P=0.500N     P=0.500      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Skin                                                                                                                             |
|     Sarcoma                                                                                                                     |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |     #            #            #            #           |#            #            #            #            |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/50 (0%)    0/50 (0%)    1/50 (2%)    1/50 (2%)   |2/50 (4%)    2/50 (4%)    0/50 (0%)    2/50 (4%)    |
|POLY-3 ADJUSTED (b)|     0.0%         0.0%         2.5%         2.5%        |4.7%         4.5%         0.0%         4.4%         |
|TERMINAL (d)       |     0/28 (0%)    0/32 (0%)    0/27 (0%)    0/28 (0%)   |0/32 (0%)    0/31 (0%)    0/39 (0%)    1/33 (3%)    |
|FIRST INCIDENCE    |     ---          ---          512          508         |667          611          ---          709          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.330      (e)          P=0.496      P=0.491     |P=0.612      P=0.690      P=0.214N     P=0.673N     |
|POLY 3             |     P=0.330      (e)          P=0.494      P=0.494     |P=0.604      P=0.683N     P=0.223N     P=0.669N     |
|POLY 1.5           |     P=0.334      (e)          P=0.497      P=0.494     |P=0.600      P=0.683N     P=0.227N     P=0.675N     |
|POLY 6             |     P=0.328      (e)          P=0.493      P=0.495     |P=0.607      P=0.687N     P=0.219N     P=0.666N     |
|LOGISTIC REGRESSION|     P=0.515      (e)          P=0.532      P=0.589     |P=0.564      P=0.674      P=0.235N     P=0.679N     |
|COCH-ARM / FISHERS |     P=0.348      (e)          P=0.500      P=0.500     |P=0.590      P=0.691N     P=0.247N     P=0.691N     |
|=================================================================================================================================|
       Date:  06/19/97                           EXPERIMENT: 88070 TEST: 04                                            Page 14
                     Statistical Analysis of Primary Tumors in Mice(B6C3F1)       -                ISOBUTENE
                                         Terminal Sacrifice at 104 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Spleen                                                                                                                           |
|     Hemangiosarcoma                                                                                                             |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/50 (0%)    1/49 (2%)    0/50 (0%)    1/48 (2%)   |3/49 (6%)    0/50 (0%)    0/50 (0%)    1/50 (2%)    |
|POLY-3 ADJUSTED (b)|     0.0%         2.3%         0.0%         2.6%        |7.1%         0.0%         0.0%         2.2%         |
|TERMINAL (d)       |     0/28 (0%)    0/32 (0%)    0/27 (0%)    1/28 (4%)   |2/32 (6%)    0/31 (0%)    0/39 (0%)    1/33 (3%)    |
|FIRST INCIDENCE    |     ---          715          ---          733 (T)     |709          ---          ---          735 (T)      |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.462      P=0.525      (e)          P=0.500     |P=0.519N     P=0.132N     P=0.095N     P=0.291N     |
|POLY 3             |     P=0.463      P=0.507      (e)          P=0.486     |P=0.524N     P=0.115N     P=0.106N     P=0.280N     |
|POLY 1.5           |     P=0.464      P=0.503      (e)          P=0.487     |P=0.527N     P=0.114N     P=0.109N     P=0.285N     |
|POLY 6             |     P=0.463      P=0.511      (e)          P=0.486     |P=0.519N     P=0.118N     P=0.103N     P=0.276N     |
|LOGISTIC REGRESSION|     P=0.458      P=0.510      (e)          P=0.500     |P=0.504N     P=0.122N     P=0.102N     P=0.273N     |
|COCH-ARM / FISHERS |     P=0.470      P=0.495      (e)          P=0.490     |P=0.528N     P=0.117N     P=0.117N     P=0.301N     |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Thyroid Gland: Follicular Cell                                                                                                   |
|     Adenoma                                                                                                                     |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/50 (0%)    0/50 (0%)    1/50 (2%)    0/49 (0%)   |1/48 (2%)    4/50 (8%)    3/49 (6%)    2/50 (4%)    |
|POLY-3 ADJUSTED (b)|     0.0%         0.0%         2.5%         0.0%        |2.4%         9.2%         6.6%         4.4%         |
|TERMINAL (d)       |     0/28 (0%)    0/32 (0%)    0/27 (0%)    0/28 (0%)   |1/32 (3%)    3/31 (10%)   3/39 (8%)    2/33 (6%)    |
|FIRST INCIDENCE    |     ---          ---          636          ---         |735 (T)      695          735 (T)      735 (T)      |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.786N     (e)          P=0.489      (e)         |P=0.515N     P=0.172      P=0.378      P=0.511      |
|POLY 3             |     P=0.787N     (e)          P=0.493      (e)         |P=0.499N     P=0.187      P=0.330      P=0.527      |
|POLY 1.5           |     P=0.784N     (e)          P=0.496      (e)         |P=0.505N     P=0.190      P=0.324      P=0.523      |
|POLY 6             |     P=0.789N     (e)          P=0.491      (e)         |P=0.495N     P=0.180      P=0.338      P=0.530      |
|LOGISTIC REGRESSION|     P=0.762N     (e)          P=0.509      (e)         |P=0.487N     P=0.173      P=0.378      P=0.511      |
|COCH-ARM / FISHERS |     P=0.776N     (e)          P=0.500      (e)         |P=0.518N     P=0.194      P=0.316      P=0.515      |
|=================================================================================================================================|
       Date:  06/19/97                           EXPERIMENT: 88070 TEST: 04                                            Page 15
                     Statistical Analysis of Primary Tumors in Mice(B6C3F1)       -                ISOBUTENE
                                         Terminal Sacrifice at 104 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Thyroid Gland: Follicular Cell                                                                                                   |
|     Carcinoma or Adenoma                                                                                                        |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |                                                        |                                                    |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     0/50 (0%)    0/50 (0%)    1/50 (2%)    0/49 (0%)   |1/48 (2%)    4/50 (8%)    4/49 (8%)    3/50 (6%)    |
|POLY-3 ADJUSTED (b)|     0.0%         0.0%         2.5%         0.0%        |2.4%         9.2%         8.8%         6.6%         |
|TERMINAL (d)       |     0/28 (0%)    0/32 (0%)    0/27 (0%)    0/28 (0%)   |1/32 (3%)    3/31 (10%)   4/39 (10%)   3/33 (9%)    |
|FIRST INCIDENCE    |     ---          ---          636          ---         |735 (T)      695          735 (T)      735 (T)      |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.786N     (e)          P=0.489      (e)         |P=0.535      P=0.172      P=0.243      P=0.315      |
|POLY 3             |     P=0.787N     (e)          P=0.493      (e)         |P=0.558      P=0.187      P=0.200      P=0.334      |
|POLY 1.5           |     P=0.784N     (e)          P=0.496      (e)         |P=0.549      P=0.190      P=0.194      P=0.330      |
|POLY 6             |     P=0.789N     (e)          P=0.491      (e)         |P=0.565      P=0.180      P=0.207      P=0.336      |
|LOGISTIC REGRESSION|     P=0.762N     (e)          P=0.509      (e)         |P=0.566      P=0.173      P=0.243      P=0.315      |
|COCH-ARM / FISHERS |     P=0.776N     (e)          P=0.500      (e)         |P=0.532      P=0.194      P=0.187      P=0.324      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Tooth                                                                                                                            |
|     Odontoma                                                                                                                    |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |     #            #            #            #           |#            #            #            #            |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     1/50 (2%)    3/50 (6%)    2/50 (4%)    2/50 (4%)   |0/50 (0%)    0/50 (0%)    0/50 (0%)    0/50 (0%)    |
|POLY-3 ADJUSTED (b)|     2.4%         6.8%         5.1%         5.1%        |0.0%         0.0%         0.0%         0.0%         |
|TERMINAL (d)       |     0/28 (0%)    1/32 (3%)    2/27 (7%)    2/28 (7%)   |0/32 (0%)    0/31 (0%)    0/39 (0%)    0/33 (0%)    |
|FIRST INCIDENCE    |     527          649          733 (T)      733 (T)     |---          ---          ---          ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.580      P=0.334      P=0.484      P=0.489     |(e)          (e)          (e)          (e)          |
|POLY 3             |     P=0.575      P=0.323      P=0.479      P=0.478     |(e)          (e)          (e)          (e)          |
|POLY 1.5           |     P=0.585      P=0.316      P=0.488      P=0.484     |(e)          (e)          (e)          (e)          |
|POLY 6             |     P=0.568      P=0.332      P=0.470      P=0.474     |(e)          (e)          (e)          (e)          |
|LOGISTIC REGRESSION|     P=0.597      P=0.264      P=0.502      P=0.501     |(e)          (e)          (e)          (e)          |
|COCH-ARM / FISHERS |     P=0.611      P=0.309      P=0.500      P=0.500     |(e)          (e)          (e)          (e)          |
|=================================================================================================================================|
       Date:  06/19/97                           EXPERIMENT: 88070 TEST: 04                                            Page 16
                     Statistical Analysis of Primary Tumors in Mice(B6C3F1)       -                ISOBUTENE
                                         Terminal Sacrifice at 104 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|Uterus                                                                                                                           |
|     Polyp Stromal                                                                                                               |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |     #            #            #            #           |#            #            #            #            |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |                                                        |3/50 (6%)    1/50 (2%)    1/50 (2%)    0/50 (0%)    |
|POLY-3 ADJUSTED (b)|                                                        |7.0%         2.3%         2.2%         0.0%         |
|TERMINAL (d)       |                                                        |2/32 (6%)    1/31 (3%)    1/39 (3%)    0/33 (0%)    |
|FIRST INCIDENCE    |                                                        |709          735 (T)      735 (T)      ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |                                                        |P=0.131N     P=0.323N     P=0.247N     P=0.115N     |
|POLY 3             |                                                        |P=0.132N     P=0.298N     P=0.280N     P=0.106N     |
|POLY 1.5           |                                                        |P=0.135N     P=0.297N     P=0.287N     P=0.109N     |
|POLY 6             |                                                        |P=0.129N     P=0.305N     P=0.274N     P=0.104N     |
|LOGISTIC REGRESSION|                                                        |P=0.124N     P=0.311N     P=0.265N     P=0.105N     |
|COCH-ARM / FISHERS |                                                        |P=0.139N     P=0.309N     P=0.309N     P=0.121N     |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|All Organs                                                                                                                       |
|     Hemangiosarcoma                                                                                                             |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |     #            #            #            #           |#            #            #            #            |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     1/50 (2%)    1/50 (2%)    2/50 (4%)    2/50 (4%)   |3/50 (6%)    1/50 (2%)    3/50 (6%)    1/50 (2%)    |
|POLY-3 ADJUSTED (b)|     2.4%         2.3%         5.0%         5.1%        |7.0%         2.3%         6.5%         2.2%         |
|TERMINAL (d)       |     0/28 (0%)    0/32 (0%)    1/27 (4%)    2/28 (7%)   |2/32 (6%)    1/31 (3%)    2/39 (5%)    1/33 (3%)    |
|FIRST INCIDENCE    |     664          715          559          733 (T)     |709          735 (T)      618          735 (T)      |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.384      P=0.737N     P=0.472      P=0.497     |P=0.331N     P=0.323N     P=0.584N     P=0.291N     |
|POLY 3             |     P=0.376      P=0.750N     P=0.487      P=0.481     |P=0.323N     P=0.298N     P=0.625N     P=0.280N     |
|POLY 1.5           |     P=0.386      P=0.754N     P=0.492      P=0.486     |P=0.331N     P=0.297N     P=0.636N     P=0.286N     |
|POLY 6             |     P=0.369      P=0.747N     P=0.482      P=0.478     |P=0.314N     P=0.305N     P=0.614N     P=0.276N     |
|LOGISTIC REGRESSION|     P=0.394      P=0.761N     P=0.508      P=0.483     |P=0.321N     P=0.311N     P=0.639N     P=0.273N     |
|COCH-ARM / FISHERS |     P=0.410      P=0.753N     P=0.500      P=0.500     |P=0.346N     P=0.309N     P=0.661N     P=0.309N     |
|=================================================================================================================================|
       Date:  06/19/97                           EXPERIMENT: 88070 TEST: 04                                            Page 17
                     Statistical Analysis of Primary Tumors in Mice(B6C3F1)       -                ISOBUTENE
                                         Terminal Sacrifice at 104 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|All Organs                                                                                                                       |
|     Hemangiosarcoma or Hemangioma                                                                                               |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |     #            #            #            #           |#            #            #            #            |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     1/50 (2%)    1/50 (2%)    3/50 (6%)    2/50 (4%)   |3/50 (6%)    2/50 (4%)    4/50 (8%)    1/50 (2%)    |
|POLY-3 ADJUSTED (b)|     2.4%         2.3%         7.5%         5.1%        |7.0%         4.6%         8.7%         2.2%         |
|TERMINAL (d)       |     0/28 (0%)    0/32 (0%)    2/27 (7%)    2/28 (7%)   |2/32 (6%)    2/31 (7%)    3/39 (8%)    1/33 (3%)    |
|FIRST INCIDENCE    |     664          715          559          733 (T)     |709          735 (T)      618          735 (T)      |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.418      P=0.737N     P=0.283      P=0.497     |P=0.248N     P=0.519N     P=0.591      P=0.291N     |
|POLY 3             |     P=0.405      P=0.750N     P=0.291      P=0.481     |P=0.236N     P=0.492N     P=0.543      P=0.280N     |
|POLY 1.5           |     P=0.417      P=0.754N     P=0.297      P=0.486     |P=0.245N     P=0.490N     P=0.530      P=0.286N     |
|POLY 6             |     P=0.396      P=0.747N     P=0.286      P=0.478     |P=0.228N     P=0.501N     P=0.557      P=0.276N     |
|LOGISTIC REGRESSION|     P=0.424      P=0.761N     P=0.303      P=0.483     |P=0.234N     P=0.510N     P=0.535      P=0.273N     |
|COCH-ARM / FISHERS |     P=0.446      P=0.753N     P=0.309      P=0.500     |P=0.262N     P=0.500N     P=0.500      P=0.309N     |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|All Organs                                                                                                                       |
|     Histiocytic Sarcoma                                                                                                         |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |     #            #            #            #           |#            #            #            #            |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     1/50 (2%)    0/50 (0%)    1/50 (2%)    1/50 (2%)   |2/50 (4%)    4/50 (8%)    2/50 (4%)    0/50 (0%)    |
|POLY-3 ADJUSTED (b)|     2.4%         0.0%         2.5%         2.5%        |4.7%         9.1%         4.3%         0.0%         |
|TERMINAL (d)       |     0/28 (0%)    0/32 (0%)    0/27 (0%)    1/28 (4%)   |2/32 (6%)    2/31 (7%)    1/39 (3%)    0/33 (0%)    |
|FIRST INCIDENCE    |     653          ---          708          733 (T)     |735 (T)      615          628          ---          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.538      P=0.495N     P=0.737      P=0.751     |P=0.080N     P=0.327      P=0.633N     P=0.231N     |
|POLY 3             |     P=0.534      P=0.491N     P=0.750      P=0.749     |P=0.077N     P=0.354      P=0.664N     P=0.221N     |
|POLY 1.5           |     P=0.542      P=0.494N     P=0.754      P=0.752     |P=0.079N     P=0.352      P=0.673N     P=0.225N     |
|POLY 6             |     P=0.528      P=0.488N     P=0.746      P=0.747     |P=0.075N     P=0.351      P=0.654N     P=0.218N     |
|LOGISTIC REGRESSION|     P=0.549      P=0.515N     P=0.760      P=0.755     |P=0.087N     P=0.344      P=0.680N     (e)          |
|COCH-ARM / FISHERS |     P=0.563      P=0.500N     P=0.753N     P=0.753N    |P=0.087N     P=0.339      P=0.691N     P=0.247N     |
|=================================================================================================================================|
       Date:  06/19/97                           EXPERIMENT: 88070 TEST: 04                                            Page 18
                     Statistical Analysis of Primary Tumors in Mice(B6C3F1)       -                ISOBUTENE
                                         Terminal Sacrifice at 104 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|All Organs                                                                                                                       |
|     Malignant Lymphoma And Histiocytic Sarcoma                                                                                  |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |     #            #            #            #           |#            #            #            #            |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     5/50 (10%)   2/50 (4%)    6/50 (12%)   6/50 (12%)  |18/50 (36%)  13/50 (26%)  19/50 (38%)  19/50 (38%)  |
|POLY-3 ADJUSTED (b)|     11.9%        4.6%         14.8%        15.1%       |40.4%        29.0%        39.9%        40.7%        |
|TERMINAL (d)       |     2/28 (7%)    2/32 (6%)    1/27 (4%)    4/28 (14%)  |14/32 (44%)  9/31 (29%)   13/39 (33%)  14/33 (42%)  |
|FIRST INCIDENCE    |     611          733 (T)      631          667         |378          506          543          583          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.236      P=0.179N     P=0.456      P=0.487     |P=0.343      P=0.221N     P=0.418N     P=0.563      |
|POLY 3             |     P=0.220      P=0.202N     P=0.475      P=0.460     |P=0.332      P=0.178N     P=0.567N     P=0.573      |
|POLY 1.5           |     P=0.233      P=0.207N     P=0.484      P=0.470     |P=0.317      P=0.175N     P=0.570      P=0.556      |
|POLY 6             |     P=0.213      P=0.199N     P=0.470      P=0.455     |P=0.346      P=0.191N     P=0.528N     P=0.581      |
|LOGISTIC REGRESSION|     P=0.234      P=0.201N     P=0.486      P=0.469     |P=0.319      P=0.181N     P=0.532      P=0.574      |
|COCH-ARM / FISHERS |     P=0.269      P=0.218N     P=0.500      P=0.500     |P=0.282      P=0.194N     P=0.500      P=0.500      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|All Organs                                                                                                                       |
|     Malignant Lymphoma: Histiocytic, Lymphocytic, Mixed,                                                                        |
|     NOS, or Undifferentiated Cell Type                                                                                          |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |     #            #            #            #           |#            #            #            #            |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     4/50 (8%)    2/50 (4%)    5/50 (10%)   5/50 (10%)  |16/50 (32%)  9/50 (18%)   17/50 (34%)  19/50 (38%)  |
|POLY-3 ADJUSTED (b)|     9.6%         4.6%         12.3%        12.6%       |35.9%        20.4%        36.0%        40.7%        |
|TERMINAL (d)       |     2/28 (7%)    2/32 (6%)    1/27 (4%)    3/28 (11%)  |12/32 (38%)  7/31 (23%)   12/39 (31%)  14/33 (42%)  |
|FIRST INCIDENCE    |     611          733 (T)      631          667         |378          506          543          583          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.279      P=0.283N     P=0.465      P=0.492     |P=0.127      P=0.096N     P=0.441N     P=0.402      |
|POLY 3             |     P=0.266      P=0.318N     P=0.481      P=0.469     |P=0.119      P=0.079N     P=0.582      P=0.398      |
|POLY 1.5           |     P=0.278      P=0.325N     P=0.487      P=0.476     |P=0.110      P=0.075N     P=0.557      P=0.386      |
|POLY 6             |     P=0.261      P=0.313N     P=0.478      P=0.468     |P=0.131      P=0.090N     P=0.564N     P=0.403      |
|LOGISTIC REGRESSION|     P=0.277      P=0.312N     P=0.487      P=0.471     |P=0.113      P=0.078N     P=0.525      P=0.395      |
|COCH-ARM / FISHERS |     P=0.312      P=0.339N     P=0.500      P=0.500     |P=0.094      P=0.083N     P=0.500      P=0.338      |
|=================================================================================================================================|
       Date:  06/19/97                           EXPERIMENT: 88070 TEST: 04                                            Page 19
                     Statistical Analysis of Primary Tumors in Mice(B6C3F1)       -                ISOBUTENE
                                         Terminal Sacrifice at 104 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|All Organs                                                                                                                       |
|     Benign Tumors                                                                                                               |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |     #            #            #            #           |#            #            #            #            |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     30/50 (60%)  32/50 (64%)  27/50 (54%)  23/50 (46%) |29/50 (58%)  35/50 (70%)  33/50 (66%)  32/50 (64%)  |
|POLY-3 ADJUSTED (b)|     68.5%        68.6%        63.6%        56.5%       |65.0%        74.8%        70.8%        68.4%        |
|TERMINAL (d)       |     21/28 (75%)  24/32 (75%)  17/27 (63%)  19/28 (68%) |21/32 (66%)  24/31 (77%)  30/39 (77%)  26/33 (79%)  |
|FIRST INCIDENCE    |     527          522          583          330         |449          572          543          596          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.116N     P=0.454N     P=0.465N     P=0.127N    |P=0.472N     P=0.152      P=0.455N     P=0.448      |
|POLY 3             |     P=0.115N     P=0.591      P=0.394N     P=0.167N    |P=0.490N     P=0.205      P=0.351      P=0.450      |
|POLY 1.5           |     P=0.082N     P=0.523      P=0.375N     P=0.144N    |P=0.503N     P=0.194      P=0.336      P=0.429      |
|POLY 6             |     P=0.168N     P=0.535N     P=0.396N     P=0.203N    |P=0.504N     P=0.206      P=0.349      P=0.443      |
|LOGISTIC REGRESSION|     P=0.093N     P=0.540      P=0.453N     P=0.154N    |P=0.366N     P=0.182      P=0.441      P=0.541      |
|COCH-ARM / FISHERS |     P=0.049N*    P=0.418      P=0.343N     P=0.115N    |P=0.539      P=0.149      P=0.268      P=0.341      |
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|All Organs                                                                                                                       |
|     Malignant Tumors                                                                                                            |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |     #            #            #            #           |#            #            #            #            |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     21/50 (42%)  19/50 (38%)  23/50 (46%)  23/50 (46%) |29/50 (58%)  29/50 (58%)  30/50 (60%)  31/50 (62%)  |
|POLY-3 ADJUSTED (b)|     45.0%        39.7%        50.8%        50.9%       |60.9%        60.7%        60.8%        63.2%        |
|TERMINAL (d)       |     7/28 (25%)   9/32 (28%)   9/27 (33%)   12/28 (43%) |15/32 (47%)  17/31 (55%)  20/39 (51%)  18/33 (55%)  |
|FIRST INCIDENCE    |     399          405          389          330         |322          506          477          527          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.250      P=0.317N     P=0.356      P=0.391     |P=0.493      P=0.531      P=0.351N     P=0.532      |
|POLY 3             |     P=0.237      P=0.376N     P=0.363      P=0.362     |P=0.440      P=0.577N     P=0.581N     P=0.489      |
|POLY 1.5           |     P=0.258      P=0.387N     P=0.385      P=0.379     |P=0.422      P=0.565N     P=0.562      P=0.475      |
|POLY 6             |     P=0.222      P=0.377N     P=0.345      P=0.345     |P=0.451      P=0.566      P=0.561N     P=0.492      |
|LOGISTIC REGRESSION|     P=0.408      P=0.525N     P=0.460      P=0.471     |P=0.311      P=0.559      P=0.436      P=0.365      |
|COCH-ARM / FISHERS |     P=0.315      P=0.419N     P=0.420      P=0.420     |P=0.374      P=0.580N     P=0.500      P=0.419      |
|=================================================================================================================================|
       Date:  06/19/97                           EXPERIMENT: 88070 TEST: 04                                            Page 20
                     Statistical Analysis of Primary Tumors in Mice(B6C3F1)       -                ISOBUTENE
                                         Terminal Sacrifice at 104 weeks 
|=================================================================================================================================|
|                   |                                                        |                                                    |
|                   |                              Males                     |                       Females                      |
|Dose               |     CONTROL      500 PPM      2000 PPM     8000 PPM    |CONTROL      500 PPM      2000 PPM     8000 PPM     |
|                   |                                                        |                                                    |
|=================================================================================================================================|
|                                                                                                                                 |
|All Organs                                                                                                                       |
|     Malignant and Benign Tumors                                                                                                 |
|                                                                                                                                 |
|                                                                                                                                 |
|---------------------------------------------------------------------------------------------------------------------------------|
|TUMOR RATES        |     #            #            #            #           |#            #            #            #            |
|-----------        |                                                        |                                                    |
|OVERALL (a)        |     41/50 (82%)  41/50 (82%)  36/50 (72%)  38/50 (76%) |43/50 (86%)  45/50 (90%)  44/50 (88%)  44/50 (88%)  |
|POLY-3 ADJUSTED (b)|     85.0%        83.6%        78.4%        83.1%       |87.7%        91.3%        89.2%        89.1%        |
|TERMINAL (d)       |     22/28 (79%)  27/32 (84%)  20/27 (74%)  24/28 (86%) |26/32 (81%)  28/31 (90%)  34/39 (87%)  29/33 (88%)  |
|FIRST INCIDENCE    |     399          405          389          330         |322          506          477          527          |
|-------------------|                                                        |                                                    |
|STATISTICAL TESTS  |                                                        |                                                    |
|-------------------|                                                        |                                                    |
|LIFE TABLE         |     P=0.542N     P=0.302N     P=0.389N     P=0.433N    |P=0.424N     P=0.390      P=0.200N     P=0.493N     |
|POLY 3             |     P=0.530N     P=0.537N     P=0.281N     P=0.516N    |P=0.568N     P=0.397      P=0.534      P=0.541      |
|POLY 1.5           |     P=0.447N     P=0.547N     P=0.226N     P=0.437N    |P=0.561N     P=0.411      P=0.544      P=0.551      |
|POLY 6             |     P=0.533      P=0.558N     P=0.347N     P=0.612N    |P=0.582      P=0.375      P=0.512      P=0.511      |
|LOGISTIC REGRESSION|     P=0.390N     P=0.595N     P=0.195N     P=0.383N    |P=0.556N     P=0.402      P=0.543      P=0.542      |
|COCH-ARM / FISHERS |     P=0.296N     P=0.602N     P=0.171N     P=0.312N    |P=0.568      P=0.380      P=0.500      P=0.500      |
|=================================================================================================================================|

(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).