PCB congeners, DDE, dieldrin and mercury in eggs from an expanding colony of cormorants (Phalacrocorax carbo)

PCB congeners, DDE, dieldrin and Hg were determined in 21 eggs and a young chick from an expanding colony of cormorants in eastern England. Levels of all contaminants were lower than most published values for this and closely related species, indicating a declining trend in environmental concentrations. The most abundant PCB congeners were 153, 138, 180 and 118. All contaminants were strongly correlated and there were significant but weak correlations between egg shell thickness and DDE, dieldrin, total PCB and several PCB congeners.