(19-02-08) MERCURY AND OTHER TRACE ELEMENTS IN FARMED AND WILD SALMON FROM BRITISH COLUMBIA, CANADA.

Kelly B, Ikonomou M, Higgs D, Oakes J, Dubetz C.

The present study reports measured levels of mercury and other trace elements in commercial salmon feed, farmed Atlantic, coho and chinook salmon (n=110) and wild coho, chinook, chum, sockeye, and pink salmon (n=91). Metal concentrations in farmed and wild salmon from British Columbia (BC) were relatively low and below human health consumption guidelines. Methylmercury (MeHg) in all salmon samples (range: 0.03-0.1 mug/g wet wt) were below the 0.5 mug/g guideline set by Health Canada. Negligible differences in metal concentrations were observed between the various species of farmed and wild salmon. Metal concentrations were generally higher in commercial salmon feed compared to farmed salmon. Mercury showed slight bioaccumulation potential in farmed salmon, with biomagnification factors (BMFs) ranging between 0.8-1.9. Other metals such as Cd, Pb and Ni exhibit biodilution, with BMFs << 1. The relatively low degree of biomagnification of metals observed in farmed salmon is likely due to the combination of low gastrointestinal absorption efficiency, negligible transfer to muscle tissue relative to other compartments and a high degree of growth dilution in these fish. Human dietary exposure calculations indicate intakes of Hg, Cd, Pb, Cu, As and Ni via farmed and wild BC salmon are a relatively small percentage of total intakes (0.05-32%) compared to other foodstuffs such as fruits, vegetables, chicken and beef (68-99%). Although total dietary exposure of Cd, Pb and Cu approached World Health Organization (WHO)-Provisional Tolerable Daily Intake (PTDI) levels, the contribution from BC salmon was < 2%. Our findings indicate farmed and wild BC salmon remain a safe source of omega-3 highly unsaturated fatty acid (n-3 HUFAs) intakes for cardio-protective and possibly other health benefits.

Source: Environ Toxicol Chem. 2008 Jan 22;:1

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