Farm-raised salmon could pose increased health risks

05/05/05 Consumption of farm-raised salmon poses greater health risks from dioxin and dioxin-like compounds than does the consumption of wild salmon, according to a study published in the May 2005 issue of the peer-reviewed journal Environmental Health Perspectives. Dioxins, pollutants associated with numerous adverse health effects (most notably cancer but also extending to suppression of the immune system, learning disabilities, increased risk of cardiovascular disease, impaired prostate development, and endometriosis), have been reported to be present at higher levels in farmed salmon, possibly resulting from the levels of dioxin-like compounds (DLCs) and other organic contaminants in the feed.

Although the study authors acknowledge recommendations from the National Academy of Sciences Institute of Medicine and the American Heart Associations that frequent consumption of fish is beneficial, the authors suggest that the risk of cancer and other health effects may outweigh the benefits that some types of seafood offer. Women who become pregnant may be at increased risk due to the effect of the toxicants on developing fetuses.

To reduce the risk associated with consumption of most farm-raised salmon based on the WHO’s guidelines, the study recommends that consumers limit consumption to less than 10 meals per month (based on one-half pound servings). For salmon from northern European farms, meal frequencies should be less than four meals per month. These consumption rates assume that exposure to DLCs is from farmed salmon only and does not account for exposure from other food and environmental sources. When analyzed using the EPA methods for dioxin risk assessment, the study concluded that consumption of farmed Atlantic salmon must be even further reduced.

Some limited food preparation practices might help to reduce the risk of consumption of salmon, according to sources cited in the study. The authors write that, “…removal of skin (and associated fat, lateral line, and belly flap) and some cooking methods do, in some cases, reduce contaminant levels in the fish. However, the amount of contaminant reduction is highly variable within species, among species, and among contaminants.”

Despite education efforts, particularly around the Great Lakes, most consumers remain unaware of these best practices. The authors "point to the urgent need for methods that are consistent among national and international agencies to develop consumption advice for contaminated fish".

The lead author of the study was Jeffery A. Foran of the Midwest Center for Environmental Science and Public Policy, Milwaukee. Other authors included David O. Carpenter, M. Coreen Hamilton, Barbara A. Knuth, and Steven J. Schwager. The research was initiated and supported by the Environmental Division of the Pew Charitable Trusts.