Influence of the mode of exposure on the low-dose carcinogenic risk assessment of benzo[a]pyrene in micea Reproduced from Chou TC, “Comparison of Dose-Effect Relationships Following Low-Dose Chronic Exposure and High-Dose Single Injection: An Analysis by the Median-Effect Principle,” Carcinogenesis, 1980, volume 1, pp 203-213, by permission of Oxford University Press. Table also used by permission of Oxford University Press in Chou and Talalay (1987).
| Parameters of the Median-Effect Plotb | Acute Experimentsb,c | Chronic Experimentsb,d |
|---|---|---|
| m | 1.3879 ± 0.0455 | 4.5693 ± 0.0630 |
| D m | 98.857 (μg/mouse) | 1578.8e (μg) |
| r | 0.9973 | 0.9981 |
| For a Given Dose (in Dm) | Acute Experiments | Chronic Experiments | ||
|---|---|---|---|---|
| Calculated Dose | Calculated Risk fa | Calculated Cumulative Dose | Calculated Risk fa | |
| μg/mouse | μg | |||
| 0.0988 | 1.85 × 10–5 | 1.579 | 1.96 × 10–14 | |
| 0.988 | 1.67 × 10–3 | 15.79 | 7.28 × 10–10 | |
| 9.886 | 3.93 × 10–2 | 157.9 | 2.70 × 10–5 | |
| 49.43 | 2.77 × 10–1 | 789.5 | 4.03 × 10–2 | |
| 98.86 | 0.50 | 1578.8 | 0.50 | |
| 197.71 | 0.7234 | 4736.3 | 0.9596 | |
↵ a Risk (fa) at a given dose was calculated from eq. 9: fa = 1/[1 + (Dm/D)m]
↵ b Parameters calculated are given in Table 12
↵ c Data from Bryan and Shimkin (1943) are used. C3h male mice were injected subcutaneously with a single dose of benzo[a]pyrene. Tumor incidence at the site of injection was histologically confirmed, spindle-cell sarcoma. Statistically calculated values reported by the original authors are used. Tumor incidence of 100% and <1% has been excluded from analysis
↵ d Data from Peto et al. (1975) are used. Benzo[a]pyrene (20 μg) in 0.25 ml of acetone, twice a week, was applied to the skin of Swiss albino female mice at 10 weeks old, treated for 100 weeks. Mice with epithelial tumors exceeding 10 mm in diameter were killed for histological examinations. The raw tumor incidence data were refined by the original authors in accordance with the life-table procedure
↵ e The total cumulated doses over a period of 39.469 weeks as calculated previously (Chou, 1980, 1981) (i.e., 20 μg/wk × 2 × 39.469 weeks = 1578.8 μg)