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Beware of this fishy health study

When two little-known groups in Washington, D.C., announced recently that pregnant and breastfeeding mothers could safely eat more fish, mercury content aside — more seafood than the federal government and most states recommend — a few eyebrows were raised in the public health world.

"Initially my thought was, 'Where is this coming from?'" said Pat McCann, a research scientist with the Minnesota Department of Health and coordinator of the state's fish advisory program. "What did they base their decision on?"

But when the report listed the American Academy of Pediatrics, the March of Dimes and the Center for Disease Control as group members, it had the sheen of legitimacy.

Or not so much.

As it happened, the "Maternal Nutrition Group" and the "National Healthy Babies, Healthy Mothers Coalition" were funded to the tune of $76,000 by a seafood industry group that supports — surprise! — eating more fish. That sponsorship was ignored in much media coverage, which showed up as far away as India.

Displeased with coverage

Some coalition members were not happy with the publicity. "We are members of the coalition, but we were not informed of this announcement in advance, and we do not support it," was the word from a spokeswoman for the U.S. Department of Health and Human Services. In the confusion that followed, the Food and Drug Administration and the Environmental Protection Agency said they were sticking with their guidelines.

"We were just shocked to see such baseless findings being so widely reported in the mainstream press," said Sonya Lunder, a senior researcher with the Environmental Working Group, a Washington, D.C.-based environmental organization. "The guidance is very clear about what is safe to eat during pregnancy. There is no controversy."

Mercury, which occurs as an element in the environment as well as in industrial compounds, builds up in fish and is toxic to the human nervous system. It has long been known as a neurotoxin — Lewis Carroll's "Mad Hatter" was based on an occupational illness of 19th-century hat-makers who rubbed mercury into felt hat brims to preserve them. It is particularly harmful to the developing nervous systems of fetuses and infants.

"Mercury affects a child's ability to learn and process information," McCann said. The early signs of mercury poisoning are tingling in the fingertips, toes and lips, she said. Blood and hair samples are taken to test for its presence. Your body will eventually exorcise it — in the way that you might think — but outflow needs to be greater than input for recovery.

A primary source of mercury in the atmosphere is through industrial emissions, including the burning of high-sulfur coal and other fossil fuels. Mercury and mercury compounds are also used in labs, hospitals and various manufacturing processes.

The federal government issued consumer advisories for seafood in 2001 and 2004 and they may have had an adverse effect on consumption; one recent study from the Medical University of South Carolina showed that pregnant women are now eating less fish.

Given the dangers of mercury and other industrial pollutants, how much fish is safe to eat?

Experts agree that consuming fish is good for you and you are probably not taking in enough. "People should eat two meals of fish per week, but make smart choices," McCann said, including selecting species high in omega-3 fatty acids and low in mercury. (A 1990s EPA study estimated that the average American eats one meal of fish about every six weeks.)

Differing guidelines

Minnesota guidelines for some species are stricter than federal standards — one meal of walleye fillets per month for pregnant women, women who may become pregnant and children under 15, for example. The Department of Health provides site-specific fish advisories as well as statewide guidelines.

The federal guideline is 12 ounces per week, which is about two hearty meals of fish with all the trimmings. And the feds, who are more concerned with commercial fish than game fish, say some ocean-goers — swordfish, shark, king mackerel, tilefish — should not be eaten at all because they typically contain high levels of mercury. Other seafood, including light tuna, salmon, catfish and shrimp, are safer for you because they aren't exposed to or don't store mercury as efficiently as a swordfish and are high in healthy oils. Slicing off the fatty parts of the fish during food preparation does not affect its mercury content because mercury — unlike PCBs, for example — bonds to muscle tissue all over the fish, not just in the belly fat.

Fish and fishing have been important in Minnesota since forever and the state has a relatively long history of research in this area. Minnesota scientists began analyzing fish for mercury in the 1960s; fish advisories were first released to the press in the mid-1970s. By 1985, the state was producing a small booklet with consumption recommendations. (The last booklet was published in 2000, when the information was shifted to the Web.)

The fish advisory program is one of those instances of inter-agency cooperation that politicians like to talk about. The Minnesota Department of Health, the Department of Natural Resources, the Department of Agriculture and the Pollution Control Agency all play a part in putting the program together.

So you're probably better off listening to Minnesota public health experts than to reports funded by the seafood industry.

One general rule: The farther up the fish food chain you go, the more danger from pollutants. "Predators are higher in mercury," McCann said. That's good news for lovers of perch, sunnies, crappies—and even bullheads.

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Comments (1)

It's refreshing to see a fish contaminants story in the health category where it belongs. The piece sheds light on an important subject. Keep up the good work.