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Farmed salmon more contaminated than wild

Farmed salmon more contaminated than wild

作者:李赅  时间:2019-03-03 03:09:01  人气:

By Rob Edwards Farmed salmon have significantly higher levels of toxic contaminants than salmon from the wild, US scientists have found. Contamination by PCBs, dioxins and pesticides is on average 10 times higher in farmed salmon. The consequent health risks, such as a raised risk of cancer, could detract from the known health benefits of eating oily fish, the scientists warn. The pollutants, widely used by industry and agriculture in the past, are now ubiquitous in fish. They accumulate in the fat of farmed salmon because the fish are fed a diet of concentrated fish oils and meal. But the salmon farming industry has always argued that the levels are too low to pose any danger. Now that assurance is facing its first serious challenge as a result of a major investigation by environmental experts at universities in Indiana, Michigan and New York. “I and my family do not eat farmed salmon,” says Jeffrey Foran, a toxicologist from the University of Michigan and one of the team. “My hope is that public health agencies will look at our study and issue advice encouraging people to eat less contaminated fish.” Ensuring fish is labelled as farmed or wild allows consumers make a better choice, the scientists say. People are currently encouraged to eat hundreds of grams of oily fish like salmon every month. This because it contains omega-3 fatty acids known to reduce the risk of death from heart attack. The scientists acknowledge that the risk/benefit analysis is complicated, but conclude: “Consumption of farmed Atlantic salmon may pose health risks that detract from the beneficial effects of fish consumption.” However, the salmon farming industry takes the opposite view, insisting that the study shows its produce is safe because the contamination did not exceed US Food and Drug Administration safety limits. “Consumers should be reassured by this research, despite its rather obvious attempt to stir anti-fish farming headlines,” says John Webster from Scottish Quality Salmon. The chairman of the UK Food Standards Agency, Sir John Krebs, agrees: “This study shows that the levels of dioxins and PCBs in salmon are within internationally recognised safety limits. We advise that the known benefits of eating one portion of oily fish outweigh any possible risks.” Webster points out that salmon farmers are already trying to minimise the levels of PCBs and dioxins by using less contaminated fish feeds. They are also investigating the possibility of introducing plant oils to feed the salmon. Salmon was once a rare and expensive delicacy. But in the past 20 years, fish farming has boosted production by 40 times, mainly in northern Europe, North America and Chile. Studies in 2002 suggested that farmed salmon might be more contaminated than wild salmon, but they were dismissed by the industry because they were based on small samples. The new investigation analysed 700 farmed and wild salmon from all over the world. The scientists compared farmed Atlantic salmon with wild salmon from the Pacific, because wild Atlantic salmon are now scarce. They discovered that concentrations of 13 organochlorine chemicals were much higher in the farmed salmon. Many of the chemicals present, including PCBs (polychlorinated biphenyls), dioxins, dieldrin, DDT and toxaphene, are thought to threaten the immune or reproductive systems and to trigger cancers. The most contaminated salmon analysed was farmed in Scotland and the Faroes. The scientists argue that risk estimates for cancer used by the US Environment Protection Agency suggest that people should eat no more than 55 grams of such fish a month, just quarter of a normal portion. Their calculated limit for farmed salmon from Canada and the US state of Maine is half a portion a month, and from Chile or Washington State, one portion a month. In contrast,