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Chinook salmon packed with PCBs
Susan Gordon
Concentrations of banned chemicals that are particularly threatening to children are at least three times higher in Puget Sound chinook salmon than in chinook from other areas.
In light of that finding by a state Department of Fish and Wildlife scientist, state Health Department officials are conducting their own research. While they say there is no cause for alarm, health officials acknowledge they might revise fish consumption warnings in a few months.
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“I don’t think the data is clear enough yet,” said Rob Duff, the Health Department’s environmental health director.
Sandie O’Neill, a state Department of Fish and Wildlife scientist, has found PCB concentrations in Puget Sound chinook are three times higher than what others have measured in chinook salmon from Alaska, British Columbia, Oregon, coastal Washington and the Columbia River.
O’Neill has studied PCBs in salmon since 1992. But comparable data from other researchers weren’t available until recently, she said.
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She first presented preliminary data to the state Fish & Wildlife Commission last October and plans to unveil more comprehensive research at the 2005 Puget Sound Georgia Basin Research Conference next week in Seattle.
O’Neill’s results underscore the persistence of dangerous contaminants in Puget Sound.
“The food chain in Puget Sound is significantly contaminated with PCBs and flame retardants,” said Jim West, another state Fish and Wildlife Department scientist.
He recently discovered both pollutants in herring, a key component of the salmon diet.
PCBs, or polychlorinated biphenyls, are banned industrial compounds found worldwide that build up in the food chain and can cause developmental and behavioral problems in children.
Although PCBs are found in meat and dairy products, some health experts believe humans are most at risk from eating contaminated fish.
However, because fish are nutritious and contain fatty acids that lower cholesterol, many experts are reluctant to suggest consumption limits based on PCBs.
“These contaminants are in every fish and every person on the planet,” Duff said.
Current state Health Department advisories warn about contaminated fish or shellfish in eight tainted locations around Puget Sound, including Tacoma’s Commencement Bay.
But that advice, which doesn’t mention salmon, is complicated and might not be sufficient, Duff said.
So Health Department researchers are testing store-bought fish for PCBs, mercury and flame retardants. The sampling list includes chinook salmon, catfish, pollack, red snapper, halibut, cod and flounder, Duff said.
After that analysis, due in about three months, state health officials could revise statewide fish consumption recommendations, Duff said.
PCBs, which cause cancer, are highly toxic compounds that can be transferred from mothers to children through breast milk. Once used to cool and insulate transformers and other electrical equipment, PCBs have been banned in the United States since 1977.
Because PCBs don’t break down over time, they persist in air, water and soil. The PCBs also build up in the food chain, so top predators harbor high concentrations. Because of PCBs, orca whales are some of the world’s most contaminated marine mammals.
In Puget Sound chinook, O’Neill measured average PCB concentrations of 53 parts per billion. That’s like a spoonful of poison in a railroad tanker car full of water, but scientists believe the toxicity of the compound makes it notable.
In Puget Sound coho, O’Neill measured average PCB concentrations of 31 parts per billion.
“These are not screamingly high levels,” Duff said.
Concentrations found in Great Lakes salmon have been many times higher.
But Puget Sound chinook, also known as king salmon, are far more contaminated than other types of salmon, such as pinks, sockeye and chum, O’Neill said. That might be because young chinook spend more time in the estuaries than other young salmon, which also feed lower on the food web.
Also, O’Neill said concentrations of PCBs in Puget Sound chinook are comparable to what others have measured in farmed Atlantic salmon from Norway and Scotland.
Confining contamination
For years, scientists have known about excessive concentrations of PCBs in bottom-dwelling Puget Sound fish, particularly those inhabiting polluted industrial areas such as Commencement Bay in Tacoma and the Seattle waterfront.
For example, state researchers have found PCBs in concentrations of 121 parts per billion in rockfish and 62 parts per billion in English sole. Both were caught in Seattle.
Harbor seals also are contaminated.
The new research suggests that efforts to confine contaminated sediments in polluted areas such as Commencement Bay might not prevent PCBs from recycling through plankton and fish, said West, O’Neill’s colleague at the Fish and Wildlife Department.
“We need to better understand the dynamic between contaminants trapped in sediments and those entrained in the (salmon) food web,” O’Neill said.
Bill Sullivan, environmental director for the Puyallup Tribe of Indians, said he wouldn’t be surprised if contaminants leak out of disposal sites.
“Obviously, we have something very wrong in the interior Puget Sound,” he said.
If state officials revamp fish consumption recommendations, Duff said special outreach efforts will be made to tribes and immigrant groups of Asians and Pacific Islanders. They often eat lots of fish and might be more vulnerable to injury than the mainstream population, he said.
Most Washington residents eat no more than two fish meals a week, and that’s probably not enough to cause harm, he said.
On the net
For state Health Department fish consumption recommendations, visit www.doh.wa.gov/ehp/oehas/EHA_fish_adv.htm.
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