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Over One Third Of Mercury Exposure From Tuna


US - A new study ranking exposure risks from methylmercury finds that tuna accounts for over one third of total mercury exposure from seafood consumption in the United States.

These key findings were published in a peer-reviewed paper by Dr Edward Groth III, "Ranking the contributions of commercial fish and shellfish varieties to mercury exposure in the United States: Implications for risk communication," and appearing in the April 2010 issue of Environmental Research.

"Canned tuna is the number one fish product consumed in the US today at just under three pounds per capita per year," said Michael Bender, director of the Mercury Policy Project. "Based on these new findings, tuna is also the number one mercury exposure risk."

Tuna contributes 37 per cent of the total mercury in the seafood supply -- almost six times as much as the combined total of the four highest mercury-laden fish: swordfish, shark, king mackerel and Gulf tilefish, according to the study.

"Eating tuna can be a toxic gamble, especially for pregnant women, mothers, babies and children," said Buffy Martin Tarbox, Campaign Coordinator for, based in Forest Knolls, California.

Dr Groth's paper explains seafood varieties differ by over 120-fold in average mercury content, so which fish you choose drives your mercury exposure. For anyone who eats fish twice a week or more, not just mothers-to-be, choosing low-mercury fish is an important health strategy.

"Unfortunately," Dr Groth notes, "most consumers have no idea which fish are high in mercury and should be avoided, or which are low in mercury and are safe to consume."

Canned "light" tuna, the most popular fish in the American diet, has an above-average mercury level, and some "light" tuna has even higher levels. Canned albacore (white) tuna and tuna steaks have still higher average mercury levels. "Women who are trying to minimize their mercury exposure should avoid all forms of tuna," says Dr Groth.

Dr Groth's study also found that two-thirds of the seafood supply and nine of the 11 most consumed fish and shellfish are low or very low in mercury. So if consumers know what to pick, they can easily find low-mercury alternatives.