Tuna Surprise: New study finds over one third of mercury exposure is from tuna

By April 21, 2010Got Mercury?


San Francisco, CA – 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 U.S. today at just under 3 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% 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 GotMercury.org, based in Forest Knolls, CA.

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,” 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 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.  

To view an abstract of Dr. Groth’s paper and also his chart grouping 51 fish varieties into six categories by mercury content, visit:  


About GotMercury.org: The Gotmercury.org works to protect people and the environment from mercury. Because of the ubiquitous nature of mercury in the environment and because federal and state public health agencies are not doing enough to raise public awareness and protect the public from mercury, GotMercury.org developed the free online mercury-in-fish calculators that have received millions of hits since 2002. For more information visit: www.gotmercury.org or www.gotmercury.mobi 

All Rights Reserved for calculator and contents of GotMercury.Org.