Mouse germ cell mutation tests in genetic risk evaluation of chemical mutagens.

That certain environmental chemicals can induce transmissible mutations in germ cells of experimental mammal is clear. The assumption that under certain conditions these chemicals are also likely to be mutagenic to human germ cells is not detectable. However, it is a difficult challenge to determine the level of human exposure at which such chemicals can be produced and used economically without significantly harming human health. Data on transmitted genetic effects in mice are necessary, not only as a measure of endpoints that are considered directly in genetic risk assessment, but also as the standard for evaluating the usefulness of non-germ-cell effects as predictors in genetic risk assessment. To carry out a "real world" genetic risk assessment exercise, in vivo mouse data are being obtained for two model chemicals--ethylene oxide and acrylamide. Both chemicals are capable of inducing transmissible genetic effects in mice; their production and use involve measurable human exposures; and, because they are socially and economically important, they are not likely to be banned altogether despite their mutagenicity. For both chemicals, data are not sufficient for accurate low-dose and low-dose-rate extrapolations.