A Method for Quantitative Assessment of Reproductive Risks to the Human Male

There is a need for quantitative assessment of reproductiverisks following human exposure to toxic agents. Current methodsonly estimate exposure levels that are unlikely to produce appreciable risk; they do not address the magnitude of risk. Thequantitative reproductive risk estimation (QRRE) approach presentedhere enables calculation of the increased incidence of infertilityin a human population resulting from exposure of males to atoxic agent. The four steps involve (A) obtaining a dose-responsecurve in experimental animals for the effect of a toxicant ona measure of reproductive function; (B) applying an interspeciesextrapolation factor (IEF) derived for a similar toxicant torelate doses in animals and humans that produce equivalent reproductivetoxicity; (C) using human exposure and uptake levels, alongwith the IEF and the dose-response curve, to calculate impairmentof the measure in humans; and (D) computing the increase inhuman infertility caused by that impairment. The QRRE methodis used to compute reproductive risks from dibromochloropropaneexposure.