Bioaccumulation and toxic potential of extremely hydrophobic polychlorinated biphenyl congeners in biota collected at a superfund site contaminated with Aroclor 1268

Aroclor 1268, a highly chlorinated technical PCB mixture composed of primarily hexa-through decachlorobiphenyls, was used to lubricate high voltage process equipment at a chlor-alkali facility in coastal southeastern Georgia. Disposal of process wastes has resulted in extensive contamination of environmental media at the nearby intertidal marsh. In this study, congener distribution, bioaccumulation properties, and toxic potential of superhydrophobic PCBs were examined in blue crab, fish,terrapin, and birds collected at this site. Lipid-normalized mean concentrations of total PCBs in blue crab, striped mullet, yellowtail, sea trout, diamondback terrapin, red-winged blackbird, boat-tailed grackle, mottled duck, and clapper rail were 197, 283, 203, 56, 14, 385, 76, 135, and 10 mu g/g, respectively. Hepta-, octa-, and nonachlorobiphenyls collectively accounted for 85-93% of the total PCB concentrations. The PCB congener profile in biota resembled that of Aroclor 1268, although the relative proportions of nona- and decachlorobiphenyls were less. Bioaccumulation of superhydrophobic congeners in biota, including terrapins and birds, was less than would be predicted from K-ow, which supports the hypothesis that these compounds have restricted membrane permeability. Superhydrophobic PCB congeners were less efficiently transferred in the food web. The concentrations of non-ortho coplanar congeners in blue crab were 7-8 orders of magnitude less than the total PCB concentrations. Despite notable concentrations of total PCBs, the 2,3,7,8-TCDD toxic equivalents (TEQs) estimated for non-and mono-ortho-PCBs in biota were minimal. The toxic effects of higher chlorinated PCBs, including di-ortho-substituted PCBs, need further investigation.