An endangered population of killer whales in Washington state and southern British Columbia is accumulating extremely high levels of PCB’s, DDT, dioxins, pesticides, and other pollutants because it feeds mainly on Chinook salmon tainted from industrial activity, according to a new study. 
Peter Ross, a researcher at Canada’s Institute of Ocean Sciences, said Chinook salmon ingest the chemical compounds as they feed in polluted near-shore waters of the Pacific Ocean. As a result, the endangered southern population of killer whales — which feeds around Washington’s Puget Sound and Vancouver Island — has levels of PCB’s 6.6 times higher than levels in a killer whale population in less polluted waters 200 miles to the north, according to the study, published in Environmental Toxicology and Chemistry. The southern population now consists of only 83 whales, and its members have the highest concentrations of PCB’s ever recorded in an animal in the wild. Such levels have been shown to suppress the immune systems of marine mammals and may be playing a role in the decline of the killer whales, Ross said.
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