Effects of Feeding Benzo[a]pyrene on Fertility, Embryos, and Young Mice2

Mice fed rations containing 0.25, 0.5, and 1.0 mg of benzo[a]pyrene per g of food absorb this hydrocarbon and develop a blue fluorescence. Benzo[a]pyrene was demonstrated spectrophotometrically in the kidney of some of these mice but not in the embryos. Apparently the maximum amount of benzo[a]pyrene that is absorbed is metabolized. A metabolite is responsible for the blue fluorescence. This blue fluorescence decreases rapidly when the benzopyrene-containing ration is discontinued. Mice do not like rations containing benzo[a]pyrene after they have been fed standard laboratory pellets. Their weight decreases and the weight curve correlates with the amount of food consumed. Mice fed the ration containing 1.0 mg of benzo[a]pyrene from weaning readily eat it and gain at the same rate as mice fed laboratory pellets. In time mice will adjust to eating food containing this hydrocarbon; however, cannibalism frequently occurs when the higher concentrations of benzo[a]pyrene are fed. This hydrocarbon in the concentrations fed these mice had no injurious effect on fertility or on the developing embryos. Mice fed 1.0 mg of benzopyrene per g of food for their entire lives reproduce. No malformations were observed and, if resorption of any embryos did occur, it was not evident.