CONGENER-SPECIFIC DETERMINATION OF PCBS IN CRABS FROM A POLLUTED FJORD REGION

Congener specific determination of polychlorinated biphenyls (PCBs) including non-ortho substituted PCBs, was carried out on crabs from a fjord area in Southern Norway which is contaminated by organochlorine compounds from a magnesium production plant. A reduction of total PCBs by 30 % from 1990 to 1992 is observed in crabs from the sampling site closest to the source. The crab PCB levels at sites further away from the source have not changed significantly during the two year period. The toxic potential of non- and mono-ortho PCBs expressed as toxic equivalents, has been calculated and compared to earlier obtained data on polychlorinated dibenzo-p-dioxins and dibenzofurans. Among the non-ortho PCBs, PCB-126 contributed most to the toxic equivalents. The corresponding contribution from the mono-ortho PCBs was much less, The dominating part, however, was from the presence of the dioxins and furans.