Predicting rodent carcinogenicity using potency measures of the in vitro sister chromatid exchange and chromosome aberration assays

In vitro sister chromatid exchange (SCE) and chromosome aberration (ABS) te sts have been extensively used to identify potential rodent carcinogens. A number of measures of potency were developed to describe in vitro SCE and A BS test results: the dose needed to induce a unit increase over the control ; the lowest effective dose; the slope of the ordinary linear regression; t he maximum observed slope; and the maximum fold increase over background. T he ability of these potency measures to predict the qualitative and quantit ative carcinogenicity of chemicals was compared to the predictivity of the qualitative in vitro responses. The results of the analyses showed that the quantitative measures of the SCE or ABS responses only minimally increased the predictivity of carcinogenesis when compared to the predictivity using the qualitative responses. (C) 1999 Wiley-Liss, Inc.