Farm-raised salmon contains more cancer-causing PCBs than wild fish and other common foods, according to a report released Wednesday by a public health advocacy group.
The study, by the Environmental Working Group, tested 10 samples of farmed salmon bought in three U.S. cities, including Portland. Farmed salmon now makes up 80 percent of fresh salmon sold around the country.
Opinions differ about whether the risk of polychlorinated biphenyls outweighs health benefits of eating seafood.
The salmon tested by the Washington, D.C.-based group would be safe under U.S. Food and Drug Administration standards for fish sold in supermarkets.
The group applied newer limits set by the U.S. Environmental Protection Agency. The study concluded that consumers should not eat farmed salmon from some regions more than once a month.
An environmental agency spokesman said, however, that the agency's tighter standards were designed to protect sport and subsistence fishermen who may eat contaminated fish as a steady diet.
Salmon farming advocates said the Environmental Working Group used the stricter EPA standard to confuse consumers who know the health benefits of salmon and other fish rich in Omega-3 fatty acids.
"If the public listened to this, our health would be negatively affected," said Charles Santerre, a professor of food and nutrition at Purdue University. "Any small additional risk of cancer is far outweighed by the benefits of fatty acids in the fish."
The report could boost demand for wild salmon from the Northwest. Last year, the United States imported more than 200,000 tons of salmon raised off the coasts of British Columbia, Chile and elsewhere.
The Environmental Working Group tested Canadian-grown salmon from two Fred Meyer stores and a Safeway in Portland. It also tested salmon from other countries bought at stores in San Francisco and Washington, D.C.
Farmed salmon on average contained PCB concentrations of 27 parts per billion, while wild salmon averaged about 5 parts per billion, the Environmental Working Group report said.
Both fall well within the food and drug administration's limits of 2,000 parts per billion.
But the EPA recommends against eating fish more than twice a week if it contains PCB levels greater than 6 parts per billion.
The long-term risk posed by PCBs in human diets is poorly known, experts say.
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