Is Farmed Salmon Safe to Eat?
The rapid growth of salmon farming has led to wider availability and lower prices of salmon, so that more people are now eating salmon instead of beef. One study advises restricting consumption of farmed salmon because of possible chemical contaminants in fish food. A more recent study published in Science (using Analytica) shows that the substantial known health benefits of salmon relative to beef overwhelm any possible slight increase in risks of farmed salmon compared to wild salmon.
This work was performed by Jouni Tuomisto and his colleagues at KTL — the National Public Health Institute of Finland (initials in Finnish). With about 850 employees, KTL does research, risk analysis, health monitoring, education, and training for public health. It also supports open source policy modeling by making the Analytica model on which it was based publicly available for download, review, and use.
A 2004 study on cancer-causing chemical contaminants in farmed salmon received widespread media coverage and raised major public concern. R. A. Hites and co-workers analyzed wild and farmed salmon samples from North and South America and Europe for organic pollutants (Science, 9 Jan. 2004, p. 226). They therefore recommended that farmed salmon should not be eaten more often than once every one to four months.
Since farmed salmon is an increasingly common part of the diet in Finland and elsewhere, Jouni Tuomisto and his research team at KTL realized that these recommendations might have a large impact on public health. The net effect requires assessment of both negative and positive effects. Farmed salmon has substantial health benefits that were ignored in the initial study by Hites et al. — including the benefits of omega-3 fatty acids. So, the KTL team decided to expand this analysis to benefits as well as risks.
KTL extends Analytica’s influence diagram notation as a Pyrkilo diagram: This adds node types to display argument structure, key issues and conclusions.
Contact: Jouni Tuomisto, tel. +358-17-201305
Full article: Tuomisto JT, Tuomisto J, Tainio M, Niittynen M, Verkasalo P, Vartiainen T, Kiviranta H, Pekkanen J. “Risk-benefit analysis of eating farmed salmon”, Science. 2004 Jul 23;305(5683):476-7
R. A. Hites et al. “Global assessment of organic contaminants in farmed salmon” Science, 9 Jan. 2004, p. 22