Dose- and time-dependent formation of biliary benzo[a]pyrene metabolites in the marine flatfish dab (Limanda limanda)

Polycyclic aromatic hydrocarbons (PAHs) are abundant pollutants, and many P AHs are carcinogenic, but only after metabolic activation. Benzo[a]pyrene ( BaP) is among the most carcinogenic PAHs. The dose and time response of two enzymes involved in BaP metabolism and the amounts of BaP metabolites excr eted into the bile were evaluated in an experiment with: dab (Limanda liman da). Ninety dab were exposed orally to one of five doses of BaP (0, 0.08, 0 .4, 2, or 10 mg/kg) and sampled at 3, 6, or 12 d after exposure. None of th e doses studied caused significant induction of either microsomal ethoxyres orufin-O-deethylase (EROD), which reflects cytochrome P450 1A (CYP1A) activ ity, or cytosolic glutathione-S-transferase activity (GST). Concentrations of biliary BaP metabolites significantly increased with dose and significan tly decreased with time after exposure. It is concluded that biliary BaP me tabolites provide a much more sensitive method than EROD (CYP1A) or GST act ivity to monitor recent exposure to PAHs in dab.