POLYCHLORINATED BIPHENYL CONGENER PATTERNS IN TISSUES FROM A SELECTION OF BRITISH BIRDS

A large selection of polychlorinated biphenyl (PCB) congeners was dete rmined in tissues from several British bird species including three se a birds, four birds of prey, and herons (Ardea cinerea). The congener ''signatures'' were consistent between different tissues of the same i ndividual, but varied within and between species. Congeners 138, 153, and 180 were dominant in most samples. Nevertheless, SIGMAPCB values w ere wide ranging (0.02-105 mug/g wet weight) and also differed conside rably in subsamples of different tissues from individual birds. Applyi ng recently reported toxicity equivalency factors (TEFs) for non-ortho , mono-ortho, and di-ortho substituted PCBs to liver concentrations of such congeners, it appears that the mono-ortho congeners 105 and 118 make a high contribution to TEFs when their toxicities are weighted by concentration. The study highlights that caution is needed when inter preting data on contaminants in wildlife, but suggests that careful sa mpling will reduce the many variables which can give rise to differing congener patterns and SIGMAPCB values.