Question

Give me the cancer slope factor(CSF) of Benzo(a)anthracene and Lead. I also need the links for websites you got these answers from.

Answer 1

Oral slope factors derived from rat bioassay data varied by gender and tumor site (Table 2-7). Values ranged from 0.04 per mg/kg-day, based on kidney tumors in males, to 0.4 per mg/kgday,based on alimentary tract tumors in males. Slope factors based on liver tumors in male and female rats (0.2 per mg/kg-day) were only slightly lower than slope factors based on alimentary tract tumors (0.2-0.3 per mg/kg-day). The oral slope factor for alimentary tract tumors in female mice was highest at 1 per mg/kg-day (Table 2-7), which was approximately fourfold higher than the oral slope factor derived from the alimentary tract tumors in male rats.
Although the time-to-tumor modeling helps to account for competing risks associated with decreased survival times and other causes of death including other tumors, considering the tumor sites individually still does not convey the total amount of risk potentially arising from the sensitivity of multiple sites—that is, the risk of developing any combination of the increased tumor types, not just the risk of developing all simultaneously. A method involving the assumption that the variability in the slope factors could be characterized by a normal distribution is detailed in Appendix C of the Supplemental Information. The resulting composite slope factor for all tumor types for male rats was 0.5 per mg/kg-day, about 25% higher than the slope factor based on the most sensitive tumor site, oral cavity and forestomach, while for female rats, the composite slope factor was equivalent to that for the most sensitive site (Table 2-7; see Appendix C of Supplemental Information for composite slope factor estimates). The overall risk estimates from rats and mice spanned about a threefold range. As there are no data to support any one result as most relevant for extrapolating to humans, the most sensitive result was used to derive the oral slope factor. The recommended slope factor for assessing human cancer risk associated with chronic oral exposure to benzo[a]pyrene is 1 per mg/kg-day, based on the alimentary tract tumor response in female B6C3F1 mice.

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