Thanks to shoddy policing by the U.S. government and the influence of the fishing industry, mercury contamination in seafood is so bad that even tuna-fish sandwiches can be risky to eat.
A Tribune investigation has shown that canned tuna presents a far greater health hazard to American consumers than what the federal government and the tuna industry have led people to believe.
The government, for example, has stated repeatedly that canned light tuna is low in mercury and a nutritious choice for pregnant mothers and children.
What they don’t tell you is that tens of millions of those cans actually contain tuna that is high in mercury. And you would never know which can is less safe from reading the labels.
A 161-pound woman–the average weight of women ages 18-45–who ate a couple of sandwiches a week of that kind of light tuna would exceed the Environmental Protection Agency’s guidelines for mercury exposure.
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The tuna in cans mainly comes from three different kinds: skipjack, yellowfin and albacore. Skipjack has the lowest level of mercury–the average woman could eat almost three cans a week without consuming risky amounts of mercury.
Albacore and yellowfin have higher levels–she could eat no more than a can a week without risk.
Albacore, also called “chunk white,” is typically labeled as such on the can.
Cans labeled as “light tuna,” however, can be made with either skipjack (a smaller fish with low mercury levels) or yellowfin (a larger fish with three times the level of mercury). Some light-tuna cans are labeled as “yellowfin” or “gourmet,” signaling to shoppers that they may contain fish that generally has higher mercury levels. Many other light-tuna cans offer no hint whether the tuna inside is skipjack or yellowfin.
Consumers, therefore, have no way of knowing which cans contain fish with higher levels of mercury.
The Food and Drug Administration, which polices the safety of commercial seafood, said it had no knowledge of these industry practices.
“We do not have information on what is put in canned light tuna,” said David Acheson, the FDA’s chief medical officer. But he said the agency stands behind its position that canned light tuna is a good choice for at-risk groups concerned about mercury exposure.
No one knows how many people have been harmed by mercury in fish.
But a recent government study estimated 410,000 babies born each year in the U.S. are at risk for mercury poisoning because of high levels in their mother’s body.
And almost all the mercury that people are exposed to comes from the fish they eat.
The canned tuna industry said mercury risks are overblown and there is no credible evidence that anyone has been harmed from eating tuna.
“There are no Americans at risk,” said John Stiker, who until recently was an executive vice president of Bumble Bee Seafoods, a leading canned tuna company.
Medical experts agree that, on balance, eating fish is good for most people.
Seafood is a low-fat source of protein, and some fish are rich in omega-3 fatty acids, which are thought to help prevent heart disease.
Still, a growing body of research shows the hazards of consuming fish contaminated with mercury.
Adults can experience memory loss, lack of concentration, tremors and dizziness. Men also face an increased risk of heart attacks, some studies suggest.
Children exposed to mercury can suffer subtle delays in walking and talking as well as decreases in attention span and memory.
Because mercury passes easily through the placenta and can harm the developing central nervous system, fetuses and small children are most vulnerable to its effects.
Many experts now believe that tuna-fish sandwiches can be risky for children.
People should consult their physician if they are concerned. Blood and hair tests can measure the amount of mercury in a person’s body.
“The fact that we poisoned our air and our oceans to such an extent that we can’t eat a damn tuna sandwich is just diabolical,” said Ayelet Waldman, a noted novelist whose daughter was diagnosed with mercury poisoning at age 5 after regularly eating tuna just once a week.
Mercury does not stay in the body forever.
It takes about six months to a year to leave the bloodstream once you stop eating the fish.
Documents and interviews show that the FDA has repeatedly failed to tell Americans about the true risks of all varieties of canned tuna, at times after heavy lobbying by the fishing industry.
For instance, when the FDA issued a mercury warning for seafood in 2001, it excluded canned tuna because, the agency said, people did not eat enough to cause harm–even though at the time canned tuna was the No. 1 consumed seafood in America. Shrimp has since become No. 1.
Last year, the FDA and EPA jointly warned pregnant women, nursing mothers, women of childbearing age and young children not to eat more than 12 ounces of fish a week, including no more than 6 ounces of canned albacore tuna.
But when the FDA updated its warning last year, it arbitrarily classified canned light tuna as low in mercury to “keep market share at a reasonable level,” one agency official told an FDA advisory panel, according to transcripts of the meeting.
One scientist on that panel quit because he thought the FDA was downplaying the risk of canned tuna.
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In interviews with the Tribune, the FDA denied it gives special treatment to the industry, saying public health decisions are based on the best scientific evidence available at the time.
“You spend so much time as a parent making the world safe for your children,” Waldman said.
“We strap 75 different kinds of helmets on our kids, and here I was exposing [her to a] neurotoxin in the food I was giving her because I thought it was healthier.”
Sushi safer?
Cooking does not remove mercury from fish because the metal is bound to the meat. For example, a piece of tuna will have the same amount of mercury whether it is eaten raw as sushi or cooked on the grill.
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Find more online
Today’s story is part of a 3-day Tribune investigative series. Read all 3 parts at chicagotribune.com/mercury, plus:
Calculator: Use the Tribune’s fish mercury calculator to determine how much of your favorite seafood is safe to eat.
Live chat: Ask reporters questions at 1 p.m. Tuesday.
Photo gallery: See where the fish you eat comes from.
Survey: Tell us about your fish-eating habits.