World media from Maine to Singapore leaped on a story in January that linked farmed salmon to much higher levels of suspected carcinogens than wild salmon. The report, which appeared in the latest issue of Science Magazine released Jan. 8, recommended consumers restrict their intake of wild salmon according to its region of origin and the levels of contaminants it contains.

Maine salmon was ranked fourth out of six, with 30 parts per billion (PPB) of PCBs and dioxin, slightly better than Scotland, the UK and the Faroe Islands.

News media response to the report was so swift, in fact, one critic said he thought some news sources might be running press releases issued by the magazine itself. The Science story was a report on a study led by scientist Ronald A. Hites, controversial not only for its findings, but for its funding source: the Pew Charitable Trusts. Many fishermen and fish farmers believe that Pew, a big funder of many environmental projects, is on a mission to end commercial fishing and fish farming.

Much of the reaction was predictable – agencies from countries where salmon farming is a major industry quickly blasted information contained in the report as old news, pointing out that even the highest levels are far below acceptable levels designated by the U.S. Federal Drug Administration.

Reaction was loudest from the U.K., with food agencies condemning the report as “scaremongering” and “misleading.” Agencies did not dispute the findings of researchers as to the levels of contaminants, just their advice to consumers to severely restrict intake of farmed salmon. Salmon is the third-most-popular type of seafood in the U.S., after canned tuna and shrimp. Americans eat more than 207,000 metric tons of the fish every year.

According to the United Nations, more than 58 percent of salmon consumed in the world comes from farms. Scottish Quality Salmon (SQS), the body that represents 65 percent of salmon producers in that country, said levels of pollutants found in the fish were well below thresholds set by the European Union and the U.K.’s Food Standards Agency (FSA). The
SQS also said the study raised no new concerns since the levels of contaminants have long been known.

One Scottish food scientist said, “Oh, dear! Another report!” calling the finding of organic contaminants in farmed salmon “an annual event.” The FSA said the health benefits derived from eating farmed salmon outweigh the possible risk from the contaminants. PCBs have long been considered carcinogenic but no direct link between their ingestion and cancer in humans has ever been proven.

However, harvesters of wild salmon on the west coast welcomed the report. One told a California newspaper, “This just confirms many things we have long suspected… I think it’s about time farmed fish get their just rewards.”

Authors of the report analyzed 700 salmon samples including farmed Atlantic salmon from six salmon-producing regions and compared it to wild Pacific salmon from Alaska and British Columbia. For the study, researchers purchased their farm-raised Atlantic salmon from retailers in London, Frankfurt, Edinburgh, Oslo, Paris, Toronto, Vancouver, Boston, Chicago, Denver, Los Angeles, New York, San Francisco, Seattle and Washington, D.C. as well as wholesalers in North America, Chile and Europe. Samples of five species of wild Pacific salmon – Chinook, Coho, Chum, pink and sockeye – were purchased for comparison.

The authors advised consumers eat no more than a quarter of a serving of farmed salmon from Northern Europe each month, half a serving monthly from farms in Canada and Maine and one monthly serving from farms in Chile or Washington state. But most media accounts failed to make the point that many consumers – especially in the U.S. – may not be purchasing salmon grown in their region or even their country.

On average, the report found a more than sevenfold difference in PCB levels between farmed and wild salmon, an average of 36.63 PPB for farmed and 4.75 PPB on average for wild. The Hites report indicated that salmon farmed in Scotland proved highest in pollutants – 51 parts per billion (PPB), while Faroe Islands and other United Kingdom salmon ranked second with 48 PPB, followed by western Canada with 34 PPB and Maine with 30 PPB. Chile and Washington State came in with the lowest levels at 18 PPB each.

What critics say the report omitted is that PCBs (polychlorinated biphenyls, a family of compounds banned in the 1970s) are found throughout the industrialized world, so it is not surprising to find higher levels of pollutants in nations, which have been industrialized for longer periods than others.

The Science report was co-authored by David Carpenter, who heads the Institute for Health and the Environment at the State University of New York at Albany. Carpenter says all salmon should be clearly labeled as wild or farmed, and its country of origin should be displayed. The US and Canadian researchers urged consumers to “significantly reduce” their consumption of farmed salmon, claiming that eating such fish led to “unacceptable cancer risks.”