Polychlorinated biphenyls and organochlorine pesticides in harbor seal pops from the inland waters of Washington State

Blubber and liver samples from eight harbor seal (Phoca vitulina) pups, found dead at Puget Sound in 1990, have been analyzed for polychlorinated biphenyl (PCB) congeners including mono-ortho and non-ortho coplanar PCBs, hexachlorobenzene (HCB), p,p'-DDE, and mirex. Four of the seals were from Smith Island in the Strait of Juan de Fuca, and four were from southern Puget Sound primary at Gertrude Island. The levels of total PCBs, p,p'-DDE, and mirex are significantly higher in the seal samples from Gertrude Island than those from Smith Island. There was no significant difference in the level of HCB in seal samples between the two locations. PCB profiles were dominated by congeners 138, 153, and 180. The new PCB toxic equivalency factors (TEF) recommended by WHO (I), and the TEF for congener 81 from Harris et al. (2) was used for calculation of the contribution to dioxin-like toxicity from the PCB congeners. PCB congener 126 was the major contributor to PCB toxic equivalents (TEQs), followed by 156. The levels of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in marine mammals from Georgia Strait/Vancouver Island (3) were presented for reference purposes. Based on our studies of PCBs and PCDD/Fs data from the literature, the overall TEQs calculated for the monitored PCBs in Smith Island seals may contribute as much if not more dioxin-like toxicity as PCDD/Fs themselves.