Chemical contamination of harbor seal pups in Puget Sound

This report summarizes the results of chemical analyses of harbor seal pups found dead at two sites in Puget Sound. The first site was Gertrude Island in southern Puget Sound and the second Smith Island in northern Puget Sound. Blubber and liver tissues were examined both for organic and trace element contaminants. A wide range of tissues were also collected and analyzed for histo-pathology.

Primary conclusions from the this study are as follows:

1) Concentrations of PCBs in the blubber of seal pups were significantly higher for Gertrude Island compared to Smith Island. Concentrations of copper, lead, and silver in the liver of seal pups, however, were significantly higher at Smith Island compared to Gertrude Island.

2) Concentrations of PCBs and DDE in seal pups from Puget Sound have declined significantly since the start of testing in 1972.

3) PCB quantification using of standard matching is not well- suited to harbor seals because the PCB congener composition does not resemble any single commercial mixture. Standard matching can provide reasonably accurate estimates of total PCBs, however, if as many peaks as possible are used in the averaging and the standard or mix of standards is carefully selected approximate the congener composition of the sample.

4) Harbor seal pups, selected to meet specific criteria as in this study, provide an extremely useful tool in monitoring trends in contaminants concentrations in the upper levels of the food chain. 


Calambokidis, J., G.H. Steiger, L.J. Lowenstine, and D.S. Becker. 1991. Chemical contamination of harbor seal pups in Puget Sound. Report EPA 910/9-91-032 to U.S. EPA, Region 10, Seattle, Washington.

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