SEATTLE (AP) Traces of industrial-strength fire retardant have turned up in wild and farm-raised salmon around the world, a study released Tuesday said.
The research, published in the journal Environment Science and Technology, was the latest blow to the nutritious reputation of salmon, which is packed with heart-healthy omega-3 fatty acids. A prior study by the same researchers recently found troubling levels of PCBs, a known carcinogen, in farm-raised salmon.
On average, wild fish were less contaminated with the fire retardant chemicals than farmed salmon, with two exceptions: chinook from Oregon and British Columbia, which tested at more than 2 parts per billion and 4 parts per billion, respectively.
The toxicity of the chemicals, called polybrominated diphenyl ethers or PBDEs, isn't fully understood. But the fish-contamination study concerns health officials and environmentalists.
''The bottom line here is pointing out ... we have a problem with PBDEs,'' said Rob Duff, director of the Washington Health Department's Office of Environmental Health Assessment. ''The levels are getting up there.''
PBDEs can harm neurological development and function in babies and young children just like mercury and PCBs, Duff said. People will generally be protected from the retardants if they follow federal and state dietary guidelines for mercury and PCBs, he said.
PCBs, or polychlorinated biphenyls, have been banned for decades, but PBDEs are still in production around the world. Bans in Europe, California and Maine will kick in over the next few years, and U.S. manufacturers voluntarily are stopping production of some forms of the fire retardant.
For now, PBDEs are still being added to a long list of common household and workplace items from computers and other electronic gear to foam seat cushions and synthetic fabrics.
The researchers analyzed 2 tons of salmon caught in the Pacific Northwest, Europe, Canada, the East Coast and Chile. They used the same fish in their PCB and PBDE studies.
Besides chinook, other Washington state wild salmon coho, chum, sockeye and pink generally had lower levels of the fire retardant than their farmed counterparts, according to the study.
Among the farm-raised salmon tested, Washington fish were the least contaminated, with concentrations of the chemicals at slightly more than 1 part per billion. The highest levels were in Scotland, where the fish tested at almost 4 ppb.
It's unclear exactly how the PBDEs leach out of products, but they've have been turning up in everything from household dust to women's breast milk.
''Add this study to the mounting evidence that shows the PBDEs are in the environment and moving up the food chain,'' said Ivy Sager-Rosenthal of People for Puget Sound, an environmental group.
The study's lead author, Indiana University professor Ronald Hites, said it ''was a real surprise to us'' to learn that some wild salmon in the Pacific Northwest had levels as high or higher than farmed fish. Studies of Puget Sound chinook and coho also have shown levels of PCBs on par with farmed fish.
Besides Hites, the study involved researchers from Cornell University, the University at Albany, the Midwest Center for Environmental Science and Public Policy and AXYS Analytical Services.
The source of PBDE contamination is likely the salmon's food. Farmed fish eat a fish meal made from ground-up smaller fish, and chinook also eat smaller fish. The other salmon species generally eat lower on the food chain, feeding on jellyfish and plankton. Pollutants such as PBDEs, PCBs and mercury tend to build up in animals, concentrating in organisms higher on the food chain, such as orcas and people. Unlike other pollutants, there are no dietary recommendations restricting how much PBDE is safe for people to eat.
Health authorities and scientists urged people to continue eating salmon, which is a good source of protein and fatty acids.
PBDEs and PCBs concentrate in the fatty tissue of the fish, so removing the skin and using cooking methods that allow fat to drip off can reduce exposure.
Next month, the state Ecology Department plans to release a draft version of a plan to reduce PBDEs.
''These things shouldn't be out in the environment when we don't know what their effects are,'' Sager-Rosenthal said.
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