Experiment and Source of Data | Carcinogen | Weeks of Treatment^{a} | Cumulative Fraction of Tumorless (1 – f_{a})^{b} | Slope (m)^{c} | Median-Effect Dose (D_{m})^{c} |
---|---|---|---|---|---|
Chronic exposure (Peto et al., 1975)^{d} | |||||
Starting age: 10 weeks | Benzo[a]pyrene | 42 | 0.99216 | 4.5693 ± 0.0630 (r = 0.9981) | 39.469 weeks |
44 | 0.98425 | ||||
46 | 0.96851 | ||||
48 | 0.95276 | ||||
50 | 0.93701 | ||||
52 | 0.88977 | ||||
54 | 0.87402 | ||||
56 | 0.85040 | ||||
58 | 0.77166 | ||||
60 | 0.70867 | ||||
62 | 0.66862 | ||||
64 | 0.65212 | ||||
66 | 0.57060 | ||||
68 | 0.51354 | ||||
70 | 0.43841 | ||||
72 | 0.37033 | ||||
74 | 0.30933 | ||||
76 | 0.30037 | ||||
78 | 0.26339 | ||||
80 | 0.22507 | ||||
82 | 0.19507 | ||||
84 | 0.13265 | ||||
Starting age: 55 weeks | Benzo[a]pyrene | 42 | 0.99024 | 4.6225 ± 0.1337 (r = 0.9917) | 41.120 weeks |
44 | 0.98010 | ||||
46 | 0.97316 | ||||
48 | 0.96597 | ||||
50 | 0.95489 | ||||
52 | 0.95109 | ||||
54 | 0.92644 | ||||
56 | 0.88793 | ||||
58 | 0.84308 | ||||
60 | 0.78719 | ||||
62 | 0.71539 | ||||
64 | 0.66450 | ||||
66 | 0.60643 | ||||
68 | 0.53731 | ||||
70 | 0.46268 | ||||
72 | 0.40959 | ||||
74 | 0.36449 | ||||
76 | 0.35503 | ||||
78 | 0.28518 | ||||
80 | 0.18780 | ||||
82 | 0.17147 | ||||
84 | 0.17147 | ||||
Experiment and Source of Data | Carcinogen | Dose | Fraction Affected (f_{a})^{e} | Slope (m)^{c} | Median-Effect Dose (D_{m})^{c} |
μg/mouse | |||||
Acute (point) exposure^{f} (Bryan and Shimkin, 1943) | |||||
Starting age: 6–13 weeks | 3-Methylchoanthrene | 125 | 0.973 | 1.9330 ± 0.040 (r = 0.9992) | 20.663 μg/mouse |
62 | 0.881 | ||||
31 | 0.668 | ||||
15.6 | 0.379 | ||||
7.8 | 0.146 | ||||
3.9 | 0.036 | ||||
Dibenz [a,h]anthracene | 62.5 | 0.912 | 1.7720 ± 0.0502 (r = 0.9984) | 16.208 μg/mouse | |
31.2 | 0.748 | ||||
15.6 | 0.494 | ||||
7.81 | 0.242 | ||||
3.90 | 0.083 | ||||
1.95 | 0.019 | ||||
Benzo[a]pyrene | 2000 | 0.988 | 1.3879 ± 0.0455 (r = 0.9973) | 98.857 μg/mouse | |
1000 | 0.960 | ||||
500 | 0.888 | ||||
250 | 0.756 | ||||
125 | 0.565 | ||||
62 | 0.358 | ||||
31 | 0.186 |
↵ a Weeks of exposure minus 28 weeks (the latent period from initiation of tumor to tumor growth of 10 mm diameter) to obtain the effective exposure period of carcinogen as indicated by Peto et al (1975)
↵ b Cumulative incidence of tumorless (i.e., cumulative 1 – f_{a}) is calculated by the life-table procedure as used by Peto et al. (1975) See original study for details
↵ c The median-effect plot was carried out by plotting log [f_{a}/(1 – f_{a})] vs. log D, where m is the slope and log D_{m} is the intercept of the plot at the median-effect axis (i.e., at log [f_{a}/(1 – f_{a})] = 0). Both m and D_{m} are obtained from least-square regression analysis and D_{m} = antilog (–y-intercept/m). The range of m values is given as mean ± S.E. and r is the linear regression coefficient
↵ d Benzo[a]pyrene was applied twice weekly to skin of Swiss albino female mice. Animals with epithelial tumors of 10 mm diameter were scored
↵ e Statistically calculated values obtained by Bryan and Shimkin (1943) are used. Tumor incidences of 100% and <1% have been excluded from analysis
↵ f Carcinogenic hydrocarbons were injected s.c. into C3H male mice. Animals with spindle cell sarcoma during life-time were scored