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Public Radio's Environmental News Magazine (follow us on Google News)

Mercury in Sea Food: How Much is Too Much

Air Date: Week of

Recent research shows that pregnant women who consume mercury tainted sea food could have children with subtle mental deficits. The federal FDA advises potential and actual moms to limit consumption of certain fish. But some health activists and state regulators say the federal agency is not doing enough. Living On Earth’s Dan Grossman reports.


KNOY: Most health experts will tell you that fish is a tasty low-fat source of protein that can help lower the risk of heart disease. They will also tell you that while most fish is safe, you may want to avoid eating some species, especially those which contain high levels of industrial pollutants, including mercury. Government advisories warn pregnant women and children to severely limit their consumption of contaminated species. But as Living on Earth's Daniel Grossman reports, some fish-eaters are still ingesting dangerous amount of mercury.

(Woman on guitar: "I've been walkin' in my sleep, countin' troubles 'stead of countin' sheep...")

GROSSMAN: Artist and amateur musician Marilyn Winston is singing a song of sorrows. The singer's had troubles of her own.

WINSTON: A couple years ago I thought something is happening to my energy. My muscle tone was getting worse instead of better. My workouts were getting harder instead of easier.

GROSSMAN: She developed a tremor, was losing hair, and was getting hard of hearing. Her doctors was perplexed at first. Then he analyzed as ample of Marilyn Winston's hair.

WINSTON: The hair analysis came back with these scary results, which showed that I was high in mercury.

GROSSMAN: A specialist told Ms. Winston the toxin was probably coming from fish, the leading source of mercury exposure. The silvery metal is released into the air by industrial smokestacks, primarily at coal-fired power plants and incinerators, and is washed into lakes and streams. The doctor said predator species at the top of the aquatic food chain, for example, freshwater large-mouth bass and ocean swordfish, are the most dangerous. Marilyn Winston was having about 4 fish meals a week, and swordfish was her favorite.

WINSTON: Then he said that a lot of this is reversible, maybe all of it is reversible. And as soon as I would stop eating the offending fish, it would start leaving my body.

(Doors open, shut)

GROSSMAN: On a recent evening, Marilyn Winston went out to eat Malaysian food.

(Milling voices, music)

WINSTON: And then, for the main dish, the hokan charmie.

GROSSMAN: She orders less fish now and has completely cut out the high-mercury species.

WINSTON: My hearing has gotten better. My energy levels have returned to, I would say, almost normal.

GROSSMAN: Others are not so fortunate. Dr. Philippe Grandjean is studying the effects of mercury on people who eat contaminated whale meat on the Fero Islands in the northern Atlantic. Dr. Grandjean is a professor of environmental medicine at Boston University. His research shows that the children of women who had the greatest mercury exposure developed subtle mental deficits. Compared with other kids, they had slower reaction time, trouble learning new words, and difficulty retrieving old ones.

GRANDJEAN: The doubling of mercury of exposure corresponds to a developmental delay of 1 to 2 months. And at age 6 or 7, when the brain develops very rapidly, a 1 to 2 month delay is quite substantial. And clearly, if you have a couple of doublings in mercury exposure, then that child may not be ready to start school at age 7. There's a definite risk that these kids are not capable of catching up.

GROSSMAN: This research is 1 of only 2 long-term studies of the health effects of mercury found in food. The other study has not confirmed Dr. Grandjean’s findings. Health experts are puzzled by the disparity, but many agree with Dr. Grandjean that it's better to be safe than sorry.

GRANDJEAN: The best advice is to refrain from eating contaminated fish during the whole of pregnancy. And any woman in the fertile age groups must be regarded as potentially pregnant.

GROSSMAN: Some of the most tainted species are freshwater fish, like large- mouth bass, walleye, and chain pickerel, though conditions vary from place to place. Nearly every state issues advisories warning freshwater anglers. But the Federal Food and Drug Administration oversees commercial fish. Most of these come from the ocean. The agency says 2 species, swordfish and shark, are tainted with enough mercury to be a concern. It advises women of childbearing age to eat these fish no more than once a month. But some think the FDA should do more.

HETTENBACH: We feel that the FDA has a lot of room for improvement.

GROSSMAN: Policy analyst Todd Hettenbach is writing an evaluation of Federal mercury policies for the Environmental Working Group in Washington, DC.

HETTENBACH: If people follow the FDA's advice alone, then they will still be taking a chance with the brains of their children.

GROSSMAN: Mr. Hettenbach says there are other problem seafoods, and he says the FDA's once a month advice is not restrictive enough. He prefers advice dispensed by New Jersey, one of several states bucking Federal policies. Alan Stern is a toxicologist in the New Jersey Department of Environmental Protection.

STERN: Women who are pregnant or likely to become pregnant are advised that it's safe to eat up to 8 ounces of canned tuna per week, providing that they don't eat any other meals of high mercury-containing fish during that week. And we also advise them to eat shark and swordfish no more than once every 2 months during that high-risk period.

GROSSMAN: Tuna has only moderate amounts of mercury, but it's the nation’s favorite fish. And Americans consume about 3 pounds of the flaky meat each year. New Jersey has recommendations for children as well. Youngsters under 7 are advised not to eat any shark and swordfish, and to limit consumption of tuna to about 2 sandwiches a week. This advice makes David Birney, director of the US Tuna Foundation, bristle.

BIRNEY: Tuna is a very safe food product. And in regards to mercury, there is absolutely no concern.

GROSSMAN: Toxicologist Alan Stern is concerned. He says these fish maybe causing damage too subtle to detect. His case is bolstered by a recent Environmental Protection Agency analysis. It estimates that about 600,000 actual or potential moms in the US and nearly 1 million young children eat 3 times what's safe. FDA officials insist nobody in the US consumes too much mercury from fish, though they refused to be interviewed on the subject.

(Voices in a market)

GROSSMAN: Some mercury specialists complain that no one is telling women about the problem. My friend Laura, who's 8 months pregnant, offered to take me shopping at an open air market to see what fish mongers tell customers.

LAURA: This looks very good, too. I think I'll get a steak of swordfish.

MAN: Small steak?

GROSSMAN: And when it comes to health advice, Laura comes up empty-handed.

LAURA: I'm pregnant. I'm wondering, is this the kind of fish that I should be careful of?

MAN: I don't know very much about that.

GROSSMAN: The fish seller pleads ignorance. Laura's obstetrician likewise said nothing about avoiding mercury in fish. Nevertheless, FDA officials insist the agency's once a month recommendation for swordfish and shark is getting out. They say women with questions about fish can consult the FDA Internet site. Many health officials worry that people hearing about the mercury problem will overreact and cut fish from their diet completely. Fish is a nutritious source of protein which, among other things, reduces the risk of heart disease, and ironically aids in fetal brain development. Others argue women and children can get good nutrition with little mercury risk simply by learning about and avoiding the most contaminated species. For Living on Earth, this is Daniel Grossman.



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