Researchers: Farm-raised salmon pose higher health risks than wild salmon

By Blaine P. Friedlander Jr.

Consuming farm-raised salmon may pose a greater health risk than eating salmon caught in the wild, according to a group of scientists who published their research Jan. 9 in the journal Science.

"It appears that the feed used for the farm-raised salmon, concentrated fish products, is the source of the chemical contaminants, while the wild salmon get their food from disparate sources," said Barbara A. Knuth, Cornell professor of natural resources and a co-author on the study. Ronald A. Hites, professor of public and environmental affairs at Indiana University, is the study's lead author.

Knuth

Schwager

The scientists analyzed more than 2 metric tons of farmed and wild salmon, gathered from North America, South America, and Europe, to test for carcinogens.

About 600 individual salmon were purchased from wholesale distributors and filleted, while nearly 150 more fillets were purchased from retail grocers in major American, Canadian and European cities. All samples, from the farmed and the wild, were analyzed by gas chromatographic, high-resolution mass spectrometry.

Concentrations of all 14 contaminants tested were significantly higher in the farmed salmon raised in Europe than in salmon raised in North and South America, researchers found.

In the comparison of farmed salmon to wild fish, 13 of 14 organochlorine contaminants such as PCBs, dioxins, toxaphene and dieldrin, were higher. Toxaphene and dieldrin are pesticides that have long been banned in Europe and North America but persist in the environment for an extended period.

Steven J. Schwager, Cornell associate professor of biological statistics and a study co-author, said that in designing the research, he knew it would be controversial and sought to maintain the integrity of the results by gathering the data with scrupulous care.

The scientists gathered information that is representative of the salmon available to consumers. "We wanted to make the research was scientifically neutral and above reproach," said Schwager. He and his colleagues ensured the soundness of the data by obtaining salmon from a diverse group of wholesalers and retailers, while also purchasing fish from the Pacific Northwest, Europe, South American and eastern North American waters.

The research, titled "Global Assessment of Organic Contaminants in Farmed Salmon," also was authored by Jeffery Foran, University of Michigan; David O. Carpenter, University at Albany; and Coreen Hamilton, AXYS Analytical Services Ltd., British Columbia, Canada. Funding for the study came from the Pew Charitable Trusts.