Researchers at Indiana University and five other research centers say increased toxin levels in farm-raised salmon may pose health risks to people who eat the economically important fish. Their study, which appears in this week's (Jan. 9) Science, is the most comprehensive analysis to date of salmon toxin concentrations.
"We think it's important for people who eat salmon to know that farmed salmon have higher levels of toxins than wild salmon from the open ocean," said IU School of Public and Environmental Affairs Distinguished Professor Ronald Hites, who led the study.
The researchers applied U.S. Environmental Protection Agency fish consumption advisory methods to determine consumption recommendations. Farmed salmon purchased for the study from supermarkets in Frankfurt, Edinburgh, Paris, London, Oslo, Boston, San Francisco, and Toronto triggered consumption recommendations of one-half to one meal of salmon per month. (A meal is defined as 8 oz. of uncooked meat.) Farmed salmon from supermarkets in Los Angeles, Washington, D.C., Seattle, Chicago, New York and Vancouver triggered a recommendation of no more than two salmon meals per month. Farmed salmon from Denver and New Orleans supermarkets both triggered a consumption recommendation of two meals of salmon per month. With very few exceptions, farmed salmon samples tested significantly exceeded the containment levels of wild salmon, which could be consumed at levels as high as eight meals per month.
The production of farmed salmon has increased 40-fold over the last two decades, thanks in large part to the world's salmon farms. Over half the salmon sold globally are raised in Northern Europe, Chile and North America.