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

The biological half-life of 31 dichloro- to decachloro-biphenyl congeners were monitored for 105 d in adult rainbow trout (Salmo gairdneri) that were exposed to a single oral dose. In whole fish increased from 5 d to no apparent elimination as the number of chlorines on the biphenyl increased. This structure–activity relationship was not as evident in muscle where ranged from < 5 to 127 d. We suggest the decline in muscle resulted from decreasing lipid levels and the redistribution of congeners within the fish. From structure–activity analysis of in whole fish we conclude that elimination is enhanced for those congeners with lower chlorine content, with no chlorine substitutions in the ortho positions, and those with two unsubstituted carbons that are adjacent (vicinal) on the biphenyl. A significant decline in total PCB content in whole fish, equivalent to a of 219 d, was partly due to the composition of the PCB mixture administered, and the selective elimination of the lower chlorinated biphenyls.