red light. farmed salmon has more PCBs than wild salmon, but scientists do not agree on how much is safe to eat.
the largest survey yet of pollutants in salmon, reported in the January 9 issue of science , found that farmed fish have levels higher polychlorinated biphenyls (PCBs) and other chlorinated organic compounds that are the only wild caught salmon. The authors argue that eating more than one portion of farmed salmon per month can walk the risk of cancer. Other experts say that the risk is outweighed by the health benefits of farmed salmon consumption.
Salmon is a good source of protein, vitamin D, and heart-friendly fats. To find out what else is in farmed salmon, the Pew Environment program funded Charitable Trusts six scientists to collect about 700 salmon from around the world and analyzed for more than 50 contaminants. The biggest difference between farmed and wild was organochlorines. Farmed salmon in Europe had the highest levels, followed by those from North America, while the Chilean salmon was the cleanest. The source of the compounds, the researchers found, was the oil and meal fed to salmon.
To determine how much is safe to eat, the team took a look more closely at the PCB and two other persistent pesticides called dieldrin and toxaphene, which have been correlated with the risk liver and other cancers. The researchers used the EPA guidelines for calculating the maximum amount of salmon that can be consumed before strengthening cancer risk of at least 1 in 100,000. For all farmed salmon, this limit was 227 grams (raw weight) every month. For some types of wild salmon from Alaska and British Columbia, the monthly consumption eight times this high was deemed safe.
A more serious problem than cancer, the team and other scientists say, are development effects. Member of the team David Carpenter, a public health physician at the University of New York, Albany, Rensselaer, recommends that premenopausal women avoid farmed salmon, because the compounds accumulate in body fat and persist for decades - where they can be transmitted to the fetus of a woman during pregnancy or passes into breast milk.
others disagree. "I think ... we should eat more farmed salmon," says Charles Santerre toxicologist at Purdue University in West Lafayette, Indiana, consultant for the salmon industry group of the Americas, based in Princeton, New Jersey. He said that contaminant levels are not high enough to pose real dangers, while omega-3 fatty acids in salmon reduce the risk of sudden cardiac death after a heart attack and are important to brain development.
At this point, it is difficult to accurately weigh the risks and benefits, especially for pregnant women, said Cutberto Garza nutritionist at Cornell University. The standard nutritional advice still contains "Vary your diet as much as possible," he said. "Include fish, but not only salmon."
Related Sites
National Academy Study: Dioxin in food supply
The website Santerre, which includes links to fish advisories EPA
of information on farmed salmon from an industry group and an environmental group
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