Health Risks and Health Benefits Associated with Eating Farmed and Wild Salmon
CALS Impact Statement
Beginning in 2004, the research team published a series of articles reporting findings about chemical contaminants in farmed Atlantic salmon and wild Pacific salmon, and suggested policy responses to address the problem. Later work in 2005 provided quantitative comparisons of health risks from potential contaminant exposure with probable health benefits associated with the omega-3 fatty acids in these fish. The team`s work provides insights to consumers about making informed choices about fish consumption to meet individual health goals.
The annual production of farmed Atlantic salmon has increased by a factor of 40 during the past two decades, and now stands at about 1 million metric tons a year. Atlantic salmon from farms in northern Europe, North America, and Chile are now available widely year-round at relatively low prices. Salmon farms have been criticized for their ecological effects, but the potential human health risks of farmed salmon consumption have not been examined rigorously. The health benefits of eating fish such as salmon have been well documented, focusing particulary on the benefits associated with omega-3 fatty acids. However, salmon are relatively fatty carnivorous fish that feed high in the food web, and as such, they bioaccumulate contaminants. The potential risks of eating contaminated farmed salmon have not been well evaluated, nor compared with the potential health benefits of salmon consumption. Contaminants of concern include a variety of organochlorines, including PCBs, dioxins, toxaphene, and dieldrin, which have been associated with a variety of cancer and non-cancer health effects, the latter including adverse neurobehavioral and immune effects. Previous studies examining contaminants in farmed Atlantic salmon are inconclusive because of their very small sample sizes and narrow geographic representation. More information is needed regarding the extent of contaminants in farmed Atlantic salmon so that consumers may make informed purchasing decisions, and policy makers may direct their efforts to critical issues associated with the quality of the food supply and of the environment generally.
Cornell faculty participated with colleagues at other universities in a global comparison of contaminant levels in farmed Atlantic salmon vs. wild Pacific salmon, an analysis of farmed salmon feed, and a comparison of omega-3 fatty acids in these fish. We measured organochlorine contaminants and omega-3 fatty acids in approximately 700 farmed and wild salmon (totaling about 2 metric tons) collected from around the world. We assessed the variation in contaminant loads between farmed Atlantic and wild Pacific salmon, and among geographic regions, and we calculated the human health risks and health benefits associated with salmon consumption. Concentrations of the contaminants we analyzed were significantly higher in farmed Atlantic salmon than in wild Pacific salmon. European-raised farmed salmon had significantly greater contaminant loads than those raised in North and South America, indicating the need for further investigation into the sources of contamination. These general contaminant trends held true for contaminant levels within salmon feed. Risk analysis indicated that consumption of farmed Atlantic salmon may pose health risks that detract from the beneficial effects of fish consumption. Our findings suggest issues that should be considered by the farmed salmon industry, salmon consumers, fish markets and grocers, and food safety policy makers. These issues include developing more vegetable-based fish feed products, labeling salmon as farmed or wild, labeling fish with the country of origin, and re-examining current food contaminant standards. Risk-benefit analysis suggested that for persons with a history of cardiac disease, the health benefits of salmon consumption associated with omega-3 fatty acid intake may outweigh the health risks associated with exposure to chemical contaminants. The results further suggest that this benefit-risk equation can be maximized by selecting farmed Atlantic salmon from less-contaminated regions (e.g., Chile). The
Hundreds of media articles (newspaper, magazine) and shows (radio, television) throughout the United States, Canada, and Europe have focused on our global assessment of contaminants in farmed vs. wild salmon since it was published in Science in January, 2004, and the later studies further examining contaminant details, and comparisons of benefits and risks. Our study has prompted dozens of hearings and policy inquiries throughout Northern Europe and the United States. Coincidentally, at the time the article was first published, I was teaching an environmental policy course in Washington, D.C. at the Cornell Center. Students read the media articles as they appeared, and observed me conducting interviews with reporters and journalists, enabling me to incorporate into the course content timely concepts related to the interface of science and public policy, and the importance of scientists and scientific discoveries to be visible to the public. Our study has been noted in outlets as diverse as The New York Times and Family Circle magazine. Discover magazine named our work the 38th most importance science story of 2004, worldwide. The findings from the story continue to be covered in environmental, nutrition, and policy-related journals and popular publications. My involvement in this work grew from almost two decades of research and outreach focusing on risk management and risk communication associated with contaminants in fish (featured in previous years' impact statements).