Comparison of teratogenic and carcinogenic risks

Risk assessment for teratogens has received much less attention than carcinogens. This may be due in part to the lack of biologically based dose-response models for teratogens. Also, there appears to be a perception that cancer risks far exceed teratogenic risks for most chemicals. This perception may be due in large part to the stringent practice of using conservative procedures to restrict cancer risk estimates to one in 100,000 or lower whereas procedures used to restrict teratogens may result in much higher risks. The purpose of this paper is to compare estimates of teratogenic and carcinogenic risks for chemicals when both effects occur in the same animal species. Similar procedures are employed here to obtain teratogenic and carcinogenic risk estimates for nine chemicals. When a similar standard of risk is applied to both effects, the relative potency of teratogens to carcinogens varied from an order of magnitude lower to an order of magnitude higher for these nine chemicals.