Calculation of benchmark doses for reproductive and developmental toxicity observed after exposure to isopropanol

Reproductive, including developmental, toxicity risk assessment has typically relied on estimation of toxicity criteria values derived from no-observed-adverse-effect levels (NOAELs). The benchmark dose (BMD) approach has been proposed as an alternative that avoids problems with NOAELs. In this analysis of the reproductive and developmental toxicity observed in a multigeneration study of rats exposed to isopropanol, the BMD approach has been applied to all effects exhibiting significant dose-response relationships. The BMD estimates were very consistent across models and across end points; they were within the range of doses (100 to 500 mg/kg/day) that has been suggested as being the NOAEL. The use of the BMD approach for analysis of isopropanol reproductive toxicity is shown to avoid the experiment-specific argument of whether a particular treatment has induced statistically significant differences, compared to controls, in favor of the estimation of experiment-independent doses corresponding to risk levels of interest. The consistency of the BMD estimates, with values of about 420 mg/kg/day, suggests that, for isopropanol, the available multigeneration study data may provide a suitable basis for considering safe exposure.