LIFE-CYCLE BIOMAGNIFICATION STUDY IN FISH

A life-cycle biomagnification model is presented for the bioaccumulation of polychlorinated biphenyls (PCBs) in fish; the model includes biotransformation, life stage, sex, and growth of the fish. Biomagnification of PCBs was studied in the guppy (Poecilia reticulata). Juvenile guppies (first generation) were fed PCB-contaminated food for 30 weeks. Thereafter, elimination was studied for 2 years. Second-generation guppies which were born in the period of elimination were also analyzed for PCBs. Low absorption efficiencies of the PCBs in juvenile guppies were found during their first life stage but efficiencies increased with age. Elimination of the PCBs can be described with pseudo-first-order kinetics. The processes that caused the decrease in the concentrations of the PCBs were growth, biotransformation, and mother-to-young transfer. In the case of the higher chlorinated biphenyls, growth dilution was the only important process. Biotransformation was the most important factor for congeners with all ortho positions substituted with chlorine and at least one pair of adjacent unsubstituted places. Second-generation guppies and their parents contained similar PCB concentrations at the same time. This may be caused by a vitellogenin-mediated transport from mother to young. Decachlorobiphenyl is probably eliminated via the offspring only.