Bioaccumulation of selected PCBs in zebrafish, three-spined stickleback, and Arctic char after three different routes of exposure

The uptake and elimination of 20 structurally diverse tetra- to heptachlori nated biphenyls were studied in zebrafish (Danio rerio), three-spined stick leback (Gasterosteus aculeatus), and Arctic char (Salvelinus alpinus). The polychlorinated biphenyls (PCBs) were administered to the fish through food , intraperitoneal injection of peanut oil, or intraperitoneal implantation of silicone capsules. The retention of the PCBs in fish exposed through the ir diet was related with the substitution patterns of the compounds. Ortho- substituted congeners with no unsubstituted meta-para positions had high bi omagnification potential. PCBs with low biomagnification all had adjacent v icinal hydrogens, indicating that congeners with this feature may have been metabolically eliminated. The retention characteristics of the PCBs in the diet-exposed and the injected zebrafish were similar. The pattern of conge ners in Arctic char indicates that they have a lower capacity to metabolize PCBs compared to three-spined sticklebacks and zebrafish. The levels in th e fish exposed to the PCBs through a silastic implant were negatively corre lated with the hydrophobicity of the congeners. Most probably congener-spec ific release rates of the PCBs from the implants mask their retention chara cteristics. It is suggested that food, mimicking the natural intake route, should be used in PCB exposure studies to validate extrapolations to natura l situations.