Biological Half-lives of Polychlorinated Biphenyl (PCB) Congeners in Whole Fish and Muscle of Rainbow Trout (Salmo gairdneri)

Abstract

The biological half-life (t1/2) of 31 dichloro- to decachloro-biphenyl congeners were monitored for 105 days in adult rainbow trout (S. gairdneri) that were exposed to a single oral dose. In whole fish t1/2 increased from 5 days to no apparent elimination as the number of Cl on the biphenyl increased. This structure-activity relationship was not as evident in muscle where t1/2 ranged from < 5-127 days. The decline in muscle resulted from decreasing lipid levels and the redistribution of congeners within the fish. From structure-activity analysis of t1/2 in whole fish, it was concluded that elimination was enhanced for those congeners with lower Cl content, with no Cl substitutions in the o-positions and those with 2 unsubstituted C that were adjacent (vicinal) on the biphenyl. A significant decline in total PCB [polychlorinated biphenyl] content in whole fish, equivalent to a t1/2 of 219 days, was partly due to the composition of the PCB mixture administered, and the selective elimination of the lower chlorinated biphenyls.