Transfer of benzo(a)pyrene into mouse embryos and fetuses.

The distribution of radioactive material within maternal and embryonic/fetal mouse tissue was studied over a period of 2 days following a single dose of 14C-benzo(a)pyrene (B(a)P) orally on days 11, 12, 13 or 18 of pregnancy. B(a)P poorly penetrated into the embryo/fetus, and 14C-radioactivity was found in embryonic tissues at concentrations one to two orders of magnitude lower than in maternal organs. If the compound was administered for 3 consecutive days at the same dose the expected cumulation was compensated for by an accelerated elimination of the substance, which is probably due to enzyme induction.