Levels of polychlorinated biphenyls, organochlorine pesticides, mercury, cadmium, copper, selenium, arsenic, and zinc in the harbour seal, Phoca vitulina, in Norwegian waters

Abstract

Residue levels of the chlorinated hydrocarbons polychlorinated biphenyls (PCBs), total DDT, α-, β- and γ-hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), and oxychlordane in blubber, and the elements mercury, cadmium, copper, selenium, arsenic, and zinc in liver, of 82 harbour seals, Phoca vitulina, were determined. The seals were found dead or dying in Norwegian waters during the disease outbreak caused by a morbilli virus in 1988. Of the chlorinated hydrocarbons, the highest concentrations were found of PCBs, which were 2–4 times higher than the total DDT concentrations. P,p′-DDE was the main contributor to the total DDT, and constituted about 80%. The PCB and total DDT concentrations ranged from 0·4–38 and 0·1–8·8 mg kg −1, respectively. The mercury concentrations ranged from 0·1–89 mg kg −1. Significantly higher mean levels of PCBs (13 mg kg −1 and mercury (16 mg kg −1) were found in blubber and liver, respectively, of seals from the Southern coast of Norway, as compared to the corresponding mean levels in seals from the Oslofjord (8·8 and 4·1 mg kg −1), and at the Northwestern coast (5·8 and 7·9 mg kg −1), respectively. A significant positive correlation was found between the concentrations of selenium and mercury. When the seals were grouped according to sex and age, females of ageclass >1 and pups of both sexes had significantly lower PCB and total DDT levels than males ageclass >1. Significantly higher hepatic mercury levels were found in seals ageclass >1 as compared to pups. Only low levels of the other organochlorines, cadmium and arsenic, were found. Copper and zinc were considered to be present at normal physiological levels. The present organochlorine and heavy metal concentrations gave no support to suggestions that organochlorines and heavy metal pollution may be directly involved in the observed seal deaths.