Photo: Close-up of tuna carcasses

Frozen tuna are unloaded on a dock in the Fiji Islands. Over 70 percent of the world's fish species are exploited or depleted, and consumer favorites like tuna are in the most danger, according to the U.N. Food and Agriculture Organization.

Photograph by James L. Stanfield

By P.W. McRandle

Republished from the pages of The Green Guide

Samples of supermarket swordfish and tuna steaks from 22 states show that these seafood products still contain mercury levels unsafe for growing children and pregnant women. In September the Environmental Protection Agency (EPA) announced that women living on the East and West Coasts had twice as much mercury in their blood (5.9 parts per billion, or ppb) than inland women (2.4 ppb). Levels higher than 3.5 ppb may pose a threat to the woman or fetus.

"I don't think that the FDA's [U.S. Food and Drug Administration's] tuna standards are protective enough of children," says Luz Claudio, Ph.D., associate professor of community medicine at the Mount Sinai School of Medicine. "Despite FDA warnings about mercury in tuna, mercury levels are high enough in 16 percent of women of childbearing age to harm fetuses," Claudio says, referring to the risk of brain damage and learning deficits the neurotoxin poses.

"The best way to get people to make informed fish choices is to post mercury information in the stores," says Jackie Savitz, director of Oceana's Seafood Contamination Campaign, which cosponsored the supermarket study. After prominently displaying mercury-warning posters in May 2003 in their seafood departments, Wild Oats saw no decline in overall seafood sales, according to Sonja Tuitele, director of corporate communications. Safeway also has agreed to put up signs.

Good news: A September 2005 study at Oregon State University's Seafood Laboratory found that troll-caught Pacific albacore have less than half the mercury of deep-sea albacore and about as much as chunk light tuna. "Albacore also has higher amounts of omega-3s than other varieties of tuna," notes Michael Morrissey, Ph.D., a professor of food science at Oregon State. A study by the Harvard Medical School (with National Institutes of Health funding), published in the October 2005 Environmental Health Perspectives, found that before birth and during early childhood the high omega-3 fatty acid content in fish could raise children's intelligence. Rather than avoid all fish, the researchers advised, women who are pregnant or of childbearing age and children should eat fish low in mercury (no more than 12 ounces [340.2 grams] per week).

Share

How to Feed Our Growing Planet

  • hub_tease2.jpg

    Feed the World

    National Geographic explores how we can feed the growing population without overwhelming the planet in our food series.

See blogs, stories, photos, and news ยป »

@NatGeoGreen on Twitter

The Great Energy Challenge

  • Photo: Aerial view of a city at night

    What Is It?

    An initiative to help you understand our current energy situation.

  • ec-100.jpg

    Personal Energy Meter

    See how you measure up against others, and how changes at home could do tons to protect the planet.

Step Up to the Challenge »