DISTRIBUTION OF BENZO[A]PYRENE IN PREGNANT RATS FOLLOWING INHALATION EXPOSURE AND A COMPARISON WITH SIMILAR DATA OBTAINED WITH PYRENE

Eight pregnant rats were exposed, on the 17th day of gestation, for 95 min to a microcondensation aerosol of benzo[a]pyrene at five differen t atmospheric concentrations between 200 and 800 mg m-3 in a 'head-onl y' inhalation chamber. Five rats were killed immediately following the exposure and three were killed at 6 h post-dosing. Concentrations of the radiolabel and 'free' benzo[a]pyrene were measured in the individu al fetuses and in the maternal blood, fat, kidney, liver and lung. Dis tribution to the fetus did not appear to be related to its position on the uterine horn and the uptake of benzo[a]pyrene was non-linear with increasing exposure concentrations, which was similar to the observat ions previously reported for pyrene. The levels of benzo[a]pyrene were much higher in the fetus and, especially, the lung than those observe d in the pyrene study; so also were the levels of total metabolites in these tissues, which might, in part, account for the carcinogenic pot ency of benzo[a]pyrene.