Toxic Mercury Levels Surging in Tuna

Consumer Reports is sounding the alarm about mercury in tuna, following a new study showing levels of the toxic heavy metal in tuna have increased dramatically over the last 15 years.

That means current federal dietary guidelines for Americans may be advising consumers to eat more than they should — particularly pregnant women and children. Consumer Reports is challenging federal health officials’ position that the benefits of eating tuna outweigh the risks.

Using the current safety limits set by the Environmental Protection Agency, a new analysis by the magazine's health experts indicates that a 48-pound child who eats more than 1.4 ounces of tuna per week — about one-third of a can, or the amount in a single sandwich — could be at risk for brain-damaging mercury exposure.

A woman weighing about 140 pounds would exceed it by eating more than 4.5 ounces weekly.

“We believe the [Food and Drug Administration] should advise stricter limits on tuna consumption and educate people about other fish that have health benefits without the risks,” says Jean Halloran, director of food policy initiatives for Consumers Union, the policy and advocacy arm of the nonprofit Consumer Reports organization.

“It isn’t simple, but that’s no excuse for the FDA to throw up its hands and give no help to pregnant women who may have a toddler to feed and a family to cook for.”

Canned tuna is the second most popular seafood in the U.S. (shrimp is No. 1) and is responsible for about 37 percent of Americans’ dietary mercury exposure.

For a decade, federal health officials have recommended that women of childbearing age and young children limit weekly consumption of albacore (white) tuna because it contains three times more mercury than canned light tuna. Even a few tuna sandwiches per week can expose some people to too much mercury, which can damage the brain and nervous system.

But now a federal committee reviewing the nation’s dietary guidelines is suggesting that that warning be eliminated — something Consumer Reports experts strongly oppose. The committee’s report is part of the government’s development of new 2015 dietary guidelines for Americans, due later this year. Its suggestion is based on a 2011 report that concluded the benefits of eating tuna outweigh the risks.

Philippe Grandjean, M.D., a leading Harvard University expert on mercury in fish, argues that panel’s report is not based on the latest research findings on tuna safety.

“The committee’s advice about tuna is based on a flawed benefit-risk calculation that overlooks a substantial body of evidence about the dangers of prenatal mercury exposure,” he said.

Earlier this year, University of Michigan researchers reported that mercury levels in yellowfin tuna had increased at an annual rate of almost 4 percent from 1998 through 2008. Rising mercury levels in oceans are tied to pollution from coal-fired power plants and other industrial sources, they suggested.

The findings echoed those of a 2009 study by the U.S. Geological Survey and Harvard University that determined mercury measured in the waters of the northern Pacific Ocean had risen 30 percent over 20 years.

Consumer Reports experts argue these new studies provide compelling evidence that federal policies need to be changed to protect consumers. But until that happens, they advise consumers to take active steps on their own to stay safe.

Among them:

Limit tuna in your diet: Pregnant women should avoid tuna entirely. Three other vulnerable groups should also limit how much they eat: women of childbearing age (no more than 4.5 ounce), young children, and people who now eat 24 ounces or more of any fish per week.

Choose canned light tuna: Mercury levels are lower in canned light tuna than in canned albacore.

Cut back on tuna sushi: Ahi tuna (yellowfin and bigeye) is very high in mercury. People in vulnerable groups should avoid it altogether; others should eat it sparingly.

Make safer seafood choices: Fish with lowest mercury levels include shrimp, scallops, sardines, wild and Alaskan salmon, oyster, squid, and tilapia. (A 132-pound person can safely eat 36 ounces per week; a 44-pound child 18 ounces). Varieties with low levels: sole, haddock, pollock, flounder, crawfish, catfish, trout, Atlantic mackerel, crab, and mullet. (A 132-pound person can eat 18 ounces per week; a 44-pound child, six).

Avoid these fish entirely: If you are a frequent consumer of any type of fish — 24 ounces or more per week — Consumer Reports recommends avoiding the following: Swordfish, shark, king mackerel, Gulf tilefish, marlin, and orange roughy.

Limit consumption of these fish: Grouper, Chilean sea bass, bluefish, halibut, sablefish (black cod), and Spanish mackerel have moderately high levels of mercury.

Eat a variety of fish: This will help minimize pollutant exposures and maximize the benefits of fish, which are a good low-calorie source of protein and omega-3 fatty acids. For most healthy adults, the American Heart Association and FDA say the benefits outweigh the risks of eating two 3.5-ounce services of fish twice a week.

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