Concentrations of Polychlorinated Biphenyls (PCB’s), Chlorinated Pesticides, and Heavy Metals and Other Elements in Tissues of Belugas, Delphinapterus leucas, from Cook Inlet, Alaska

Tissues from Cook Inlet beluga whales, Delphinapterus leucas, that were collected as part of the Alaska Marine Mammal Tissue Archival Project were ana­ lyzed for polychlorinated biphenyls (PCB’s), chlorinated pesticides, and heavy metals and other elements. Concentrations of total PCB’s (∑PCB’s), total DDT (∑DDT), chlor­ dane compounds, hexachlorobenzene (HCB), dieldrin, mirex, toxaphene, and hexachlor­ ocyclohexane (HCH) measured in Cook Inlet beluga blubber were compared with those reported for belugas from two Arctic Alaska locations (Point Hope and Point Lay), Greenland, Arctic Canada, and the highly contaminated stock from the St. Law­ rence estuary in eastern Canada. The Arctic and Cook Inlet belugas had much lower concentrations (∑PCB’s and ∑DDT were an order of magnitude lower) than those found in animals from the St. Lawrence estuary. The Cook Inlet belugas had the lowest concentrations of all (∑PCB’s averaged 1.49 ± 0.70 and 0.79 ± 0.56 mg/kg wet mass, and ∑DDT averaged 1.35 ± 0.73 and 0.59 ± 0.45 mg/kg in males and females, respectively). Concentrations in the blub­ ber of the Cook Inlet males were signifi­ cantly lower than those found in the males of the Arctic Alaska belugas (∑PCB’s and ∑DDT were about half). The lower levels in the Cook Inlet animals might be due to dif­ ferences in contaminant sources, food web differences, or different age distributions among the animals sampled. Cook Inlet males had higher mean and median con­ centrations than did females, a result attrib­ utable to the transfer of these compounds from mother to calf during pregnancy and during lactation. Liver concentrations of cadmium and mercury were lower in the Cook Inlet belugas (most cadmium values were <1 mg/kg and mercury values were 0.704–11.42 mg/kg wet mass), but copper levels were significantly higher in the Cook Inlet animals (3.97–123.8 mg/kg wet mass) than in Arctic Alaska animals and similar to those reported for belugas from Hudson Bay. Although total mercury levels were the lowest in the Cook Inlet population, methylmercury concentrations were similar among all three groups of the Alaska ani­ mals examined (0.34–2.11 mg/kg wet mass). As has been reported for the Point Hope and Point Lay belugas, hepatic concentra­ tions of silver were relatively high in the Cook Inlet animals and positively corre­ lated with mercury and selenium concen­ trations in the liver.