PCBS, DDE, DDT AND TCDD-EQ IN 2 SPECIES OF ALBATROSS ON SAND ISLAND, MIDWAY ATOLL, NORTH PACIFIC-OCEAN

Concentrations of total polychlorinated biphenyls (PCBs) and organochl orine insecticides, including the 1,1,1-trichloro-2, 2'-bis-p-chloroph enyl-ethane (DDT) complex, were measured in the plasma of chicks and a dults and in eggs of Laysan albatrosses (Diomedea immutabilis) and bla ck-footed albatrosses (Diomedea nigripes) in a remote area of the cent ral North Pacific Ocean. Significant differences in total concentratio ns of PCBs, DDT, and 1,1-dichloro-2,2'-bis-p-chlorophenyl-ethylene (DD E) in the plasma were detected between species and among sampling peri ods. Current concentrations of DDE in eggs of Laysan albatrosses are w ell below the threshold for eggshell thinning, based on the sensitivit ies of other fish-eating birds, whereas concentrations of DDE in eggs of black-footed albatrosses were approximately one-half of the thresho ld concentrations necessary for eggshell thinning. The shells of Laysa n and black-footed albatross eggs are not currently exhibiting signifi cant thinning that is resulting in population-level effects. Current c oncentrations of PCBs are near those that could be having subtle popul ation-level effects in the black-footed albatross, but not in the Lays an albatross. The hazard posed to the albatrosses by current concentra tions of PCBs was assessed by calculating a hazard quotient (HQ), base d on composite dose-response relationships for other species. Dioxin e quivalents (TEq) based on mammalian toxic equivalency factors resulted in the greatest HQ, which was near the concentration when embryo leth ality and deformities are observed in fish-eating colonial waterbirds of the North American Great Lakes. Current concentrations of both PCBs and the DDT complex were similar to those in some species of piscivor ous birds of the North American Great Lakes region.