A 2005 study published in the Journal of Nutrition compared
the health benefits of farmed salmon to health risks. The study found
that consumers, especially young children and women of child-bearing
age, concerned about health impairments—such as reduction in IQ and
other cognitive and behavioral effects—can minimize their exposure to
cancer causing contaminants by choosing wild salmon or by selecting
other sources of omega-3.
Research
published in the Journal of the American Medical Association in October
2006, encourages the overall consumption of seafood for its health
benefits. However, the study still provides evidence showing wild
salmon as a less contaminated source of omega-3 than farmed salmon. A 2004 study in Environmental Science & Technology concluded
that frequently eating farmed salmon is more likely than
wild to boost levels of dangerous chemicals, including PCBs, in
people’s bodies. (Polychlorinated Biphenyls, or PCBs, are persistent, cancer-causing
chemicals that were widely used from the 1930s to the 1970s and are now
banned from North America.) The study, A
Global Assessment of Organic Contaminants in Farmed vs. Wild Salmon:
Geographical Differences and Health Risks, found that farmed
salmon have up to 10 times higher levels of PCBs and dioxins than
wild salmon. While a great deal of research on chemical contaminants in farmed
salmon has isolated a single persistent organic pollutant (i.e.,
PCBs), consumers also need to be concerned about interactions between
chemicals. In the study, 13 persistent organic pollutants were found.
Each
of these 13 chemicals measured 10 times greater in farmed salmon than in
their wild counterparts with some regional variations. These include:
PCBs, dieldrins, toxaphenes, dioxins and chlorinated pesticides.
Almost all of the contaminants found in farmed salmon are known as
“probable” or “possible” human carcinogens according to the U.S. Environmental Protection Agency (EPA). The researchers concluded that, in spite of the heart healthy benefits
of omega-3 fatty acids in all salmon, frequent consumption of farmed
salmon is more likely than wild to boost the levels of toxic chemicals
that are increasingly found in people's bodies.
Another groundbreaking study published in the esteemed journal Science found that in most cases, consuming more than one serving of farmed salmon per month could pose unacceptable cancer risks. The article reported that concentrations of contaminants are significantly higher in farmed salmon than in wild, and that eating farmed Atlantic salmon may pose health risks that detract from the positive effects of seafood consumption. The Science article was published in 2004 and is regarded as the most thorough analysis of farmed and wild salmon to date.
Utilizing the U.S. Environmental Protection Agency's consumption advisory for cancer, the following consumption restrictions for the general public are advised for farmed salmon produced in the following regions:
- North America - one serving every 2.5 months
- South America - one serving per month
- Europe - one serving every five months.
