Chemical flame retardants found in farmed salmon

BLOOMINGTON, Indiana, August 10, 2004 (ENS): Farmed salmon are contaminated with much higher levels of chemical flame retardants than most wild salmon, new research demonstrates.

Ronald Hites, distinguished professor at Indiana University and lead researcher on the study, studied polybrominated diphenyl ethers (PBDEs), a group of flame retardant chemicals used in electronics, upholstery, and other consumer products. He determined that the contamination is linked to the high fat diet that farmed salmon are fed.

Wild salmon eat a diverse diet of aquatic organisms, but farmed salmon are fed a high fat diet of ground up fish and fish oil. Since chemical contaminants fish are exposed to during their lives are stored in their fat, the high fat food carries more contaminants to the farmed salmon.

"PBDEs are structurally similar to PCBs, which have been linked to cancer and to reproductive, neurological, and developmental effects in humans," said Hites. "Even though no quantitative risk estimates have been done for PBDEs, public health experts are concerned because the concentrations of these substances in people have been increasing so rapidly."

The Pew Charitable Trusts sponsored the study. Pew has sponsored major research on fisheries, including a number of widely reported recent studies on the deterioration of the marine environment.

The study published this week in the journal "Environmental Science and Technology" concludes that, in spite of the heart healthy benefits of omega-3 fatty acids in all salmon, frequent consumption of farmed salmon is more likely than wild to boost levels of PBDEs.

The amounts of PBDEs detected in people and wildlife appear to have doubled in North America every four to five years since the 1970s, a pace unmatched by any other contaminant. Electronics companies including Sony and Toshiba and at least one major furniture maker, Ikea, have phased out PBDEs from their products.

The data on PBDE concentrations in farmed and wild salmon come out of the world's largest scientific sampling of salmon yet published in a recognized peer-reviewed journal.

The study analyzed fillets from about 700 farmed Atlantic salmon and wild Pacific salmon. The farmed salmon was produced in each of the eight major farmed salmon producing regions in the world or purchased in 16 large cities in North America and Europe. The study's authors, six U.S. and Canadian researchers representing fields from toxicology to biology to statistics, selected salmon samples to be representative of the salmon typically available to consumers.

While wild salmon as a group were generally the least contaminated with PBDEs, PBDE concentrations were highest in wild Chinook from British Columbia and in farmed salmon from Scotland and Western Canada.

The lowest concentrations of PBDEs were found in the other wild salmon and in farmed salmon from Chile and Washington State. The level of PBDEs in the salmon appear to be related to what the fish eat.

One unusual finding involved the relatively high PBDE concentrations in the wild Chinook samples. The authors found significant and unexpected differences in PBDE concentrations among the different species of wild salmon suggesting that different feeding behavior - for example, chinook tend to feed higher on the food chain - and other biological differences among the species could account for these differences.

The British Columbia Salmon Farmers Association says the levels of flame retardant are so low, people who eat farmed salmon are not in danger. "While PBDEs are present in many fish in North America, there is no evidence to suggest any harm to humans from eating fish with the very low levels reported," the association said Monday.

"The difference in levels found in wild or farmed fish is recorded in parts per billion and the levels reported are very low." said Mary Ellen Walling, executive director of the B.C. Salmon Farmers Association.

"There are two important things for consumers to know," Walling said. "First and most importantly, both wild and farmed salmon are a healthy and nutritious food with significant health benefits. And secondly, even though wild B.C. Chinook had the highest levels reported, there is no meaningful difference between the levels found in wild and farmed salmon. Both are safe."

Fresh water fish such as striped bass and mountain whitefish were found to generally have higher levels of the flame retardant chemicals than salt-water species, Walling said.

The salmon farmers' association has a lot to lose if consumers begin to believe that farmed salmon are not safe food. British Columbia, Canada's largest aquaculture producing province, generated sales of C$329.6 million in 2002, up 12.3 percent from 2001.

The findings released this week expand on a January study published in the journal "Science" which found that farmed salmon contained higher levels of cancer causing PCBs, dioxins, and some pesticides than did wild salmon.

That study concluded that concentrations of some contaminants were so high that more than one meal of farmed salmon per month could pose unacceptable cancer risks. The majority of salmon served in restaurants and found on grocery store shelves is farmed rather than wild.

Beginning next month, U.S. supermarkets will be required to label salmon farmed or wild along with country of origin under a 2002 law. Salmon purchased in restaurants and fish markets are not covered by this law.

Consumers should be aware that the word "Fresh" on the label does not mean the salmon is wild-caught from the ocean. And any salmon labeled "Atlantic" in the U.S. is almost always farmed because wild Atlantic salmon are rare and endangered.

Copyright Environment News Service (ENS) 2004. All Rights Reserved.

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