Disposition and metabolic fate of benzo[a]pyrene in the common carp

The biological fate of intraperitoneally administered benzo[a]pyrene (BP) was investigated in the wild strain of common carp (Cyprinus carpio) maintained in flowing water. The tissue distribution of BP-derived radioactivity was determined at 24 and 72 h after treatment. Bile contained high concentrations of BP-derived radioactivity (7.9 μg BP equivalents g bile at 72 h), which amounted to 25% of the radioactivity found in the fish at this time point. The major components of bile collected at 72 h were glucuronides (54%), sulfates (12%) and unmetabolized BP (14%). The potentially genotoxic metabolite BP-7,8-dihydrodiol and its glucuronide represented 0.7 and 20%, respectively, of the radioactivity of the bile at 72 h. High concentrations of BP-derived radioactivity were also present in liver and gonads (1,060 and 843 ng equivalents of BP g tissue at 24 h, respectively). Muscle contained 10% of the BP-derived radioactivity found in the fish (46 ng eq g at 24 h). No significant change was found between 24 and 72 h in the concentrations or proportional amounts of BP-derived radioactivity except in liver, in which the proportional amount decreased from 19 to 10% of the total found in the fish. In muscle, unmetabolized BP represented 95% of the radioactivity that could be extracted with ethyl acetate and characterized by HPLC. At 24 h BP-7,8-diol represented 0.6% of this extractable radioactivity in muscle and 1.0% of the extractable (0.4% of the total) radioactivity in liver. These data indicate that carp tissues produce significant amounts of BP-7,8-diol and its glucuronide, potentially capable of being converted (after hydrolysis of the glucuronide) to active metabolites capable of alkylating DNA and other macromolecules. However, only relatively small amounts of covalently bound radioactivity were found (amounting to 4% and 7% of the total radioactivity present in muscle and liver, respectively).