Disposition and cellular binding of H-3-benzo(a)pyrene at subzero temperatures: studies in an aglomerular arctic teleost fish - the polar cod (Boreogadus saida)

Autoradiography at different levels of resolution was used to study the dis position of the polycyclic aromatic hydrocarbon benzo(a)pyrene (H-3-BaP) in juvenile and sexually mature polar cod (Boreogadus saida). Exposure took p lace via the water or after intragastric administration at subzero temperat ures. In water-exposed fish, high total tissue levels were found in the gil ls, olfactory organ, anterior kidney, liver, skin and intestinal wall. Only traces of radioactivity were present in the muscle, brain and gonads. No m ajor differences in tissue levels or in general distribution pattern betwee n males, females or juvenile fish were observed. The gills appeared to be t he absorption site for exposure via water. After oral administration, tissu e levels of H-3-BaP-derived radioactivity were negligible. Following both a dministration routes, levels of radioactivity were highest in the bile and intestinal contents while only traces were observed in the urine, indicatin g biliary excretion as the major excretory pathway in this aglomerular spec ies. Tape-section autoradiography of fish exposed via water revealed tissue -bound residues of H-3-BaP in the olfactory organs, gills, kidney, liver, s kin and intestinal mucosa. Light-microscopy autoradiography demonstrated th at the bound residues in the olfactory organ, gills and anterior kidney wer e localized in epithelial cells, while those in liver and intestinal mucosa were evenly distributed. In conclusion, the present study shows that BaP i s absorbed from the water via the gills at subzero temperatures, that tissu e levels are considerably higher after water exposure than after dietary ex posure, that biliary excretion is predominant and, finally, that site-speci fic tissue binding in the olfactory organs, gills and anterior kidney is co nfined to epithelial cells.