Mercury Levels in Seafood Questioned

Mercury is poison. And yet it is on dinner plates everywhere -- in sea bass served in fancy restaurants, in tuna casserole ladled out at home.

Most of the time, there is so little mercury, it goes unnoticed. But that doesn’t mean the mercury in swordfish, shark, trout or snapper is harmless. Eat enough -- or eat enough fish from especially polluted waters -- and it can make you sick.

Too much mercury damages the nervous system, especially the brain. Too much in pregnant and breast-feeding women, or those who may become pregnant, can hurt their babies -- adversely affecting children’s intelligence, coordination and memory. Children under 7 are vulnerable too because their young brains are still forming.

But how much is too much? And are adults at risk as well?

Rising public concern about those questions, which have been in the background for years, is prompting public health officials to look more seriously at mercury and its effects. After a four-year moratorium, the U.S. Food and Drug Administration is set to decide this month whether to resume measuring mercury in fish. The Environmental Protection Agency will host a conference beginning Sunday in Burlington, Vt., to discuss cases in which people are believed to have been sickened by mercury in fish.

State and federal officials disagree over what constitutes a safe exposure level; their programs for monitoring mercury in fish are an on-again, off-again hodgepodge full of scientific holes. There are no long-term studies on Americans, and some of the studies that have been done are contradictory or involve people whose diets are far different from that of Americans.

There are those who say mercury in seafood is a menace, perhaps the biggest threat to childhood development since scientists discovered lead exposure lowers IQ. They say emissions from oil- and coal-powered plants are spreading this poison to an alarming degree.

There are others who say the threat is overblown -- that fish, loaded with protein and heart-healthy Omega 3 fatty acids, is so good for you, it outweighs any concern.

The fact is, no one knows.

“We’re all looking for the truth. I don’t think anybody knows what the truth is,” said Dr. Spencer Garrett of the National Marine Fisheries Service.

Suzie Piallat has a name for it: “fish fog.” Piallat, of Tiburon, Calif., was tired and achy and she couldn’t concentrate. Finally, she went to Dr. Jane Hightower, a San Francisco internist.

When Hightower asked Piallat if she ate a lot of fish, she said yes -- eight meals a week. And when Hightower tested her blood, she found mercury levels of 76 parts per billion, 15 times the amount considered safe by the federal Centers for Disease Control and Prevention.

“I’m a health nut; I’ve always done the healthy thing. I never heard any of the warnings,” Piallat said. “I thought eating fish was good for me.”

Piallat -- who cut back on her fish consumption and soon felt better -- can’t be faulted for missing those warnings. It is only recently that some doctors have reported that adult patients are being harmed by mercury in fish.

“I see people in my practice, sick from eating way too much commercial seafood, on a regular basis,” Hightower said.

Her peer-reviewed study of seafood consumption and high mercury levels in her patients, many of whom report symptoms such as aching joints and exhaustion, is slated for publication by the National Institutes of Health this fall.

There is no doubt that these patients feel sick, and no doubt that they have high levels of mercury in their blood. But, as of yet, no study has proven that the mercury caused their illness, although Hightower notes many of her patients’ symptoms are consistent with mercury poisoning.

There are skeptics, and there is much confusion about safe levels and whether they vary from person to person.

“It’s not an absolute, like over this level everybody dies and below this level nobody gets sick,” said Dr. Henry Anderson, medical officer at the Wisconsin Bureau of Public Health, who studied a family contaminated with mercury after eating fish meals three to four times a week.

“It’s like being on a highway; how many miles above the limit can you go without getting arrested? There are a lot of factors and some chance,” Anderson said.

Dr. Michael Gochfeld, a clinical professor of environmental and community medicine at Rutgers University in New Jersey, said he sees two or three patients a year with elevated mercury levels from eating too much mercury-laden fish.

“Ironically, these are usually health-conscious people who have shifted their diets away from red meat to fish,” he said. “Some people eat 10 fish meals a week.”

The latest FDA guidelines recommend that pregnant women and small children eat no more than two meals of fish each week.

The recommendation is based on a study conducted in the Faroe Islands, a remote archipelago in the North Atlantic between Norway and Iceland.

The Faroes researchers, from Boston University, found that children whose mothers’ diets featured whale meat or blubber during pregnancy had lower scores on a battery of tests designed to measure intelligence, coordination, memory and similar skills. Children exposed to the most mercury in utero were especially impaired in language, memory and attention.

But even children exposed to relatively low levels, comparable to the upper end of the range found in the U.S. population, had some impairment.

There are some problems with the Faroes study:

* It focuses on exposure of fetuses and embryos to mercury, while the FDA uses it to gauge safe limits for adults.

Still, it may be better than the research the EPA used until recently to set its standards -- a 1971 study of people in Iraq who mistakenly ate mercury-contaminated grain. A onetime poisonous dose of mercury -- 459 people died in that incident -- is not the same as long-term exposure to slightly elevated levels.

(The most notorious incident of mercury seafood poisoning occurred in Japan. Beginning in the 1950s, more than 1,400 people died and thousands of others were sickened or crippled from eating fish tainted by mercury in Minamata Bay.)

* The FDA guidelines use the Faroes study to establish the number of fish meals any one person could safely eat. In calculating that figure, the agency did not take into account that fish from some waters have far more mercury than the average serving of commercial seafood.

Freshwater fish sampled by states bordering the Gulf of Mexico, for example, average 3 1/2 times as much mercury as the average for commercial seafood, according to a computer-assisted analysis by the Associated Press.

Also, the Faroes results are based on people who eat whale, a mammal rather than a fish.

* A second study -- conducted in the Seychelles islands in the Indian Ocean off Africa -- found no ill effects from elevated exposure to mercury in fish during fetal development.

The University of Rochester scientists who conducted the Seychelles study, which was published in 1998, have struggled to explain why their results are so different from those of the Boston researchers. Maybe the Faroes results were skewed because of PCBs in whale blubber (the researchers deny it). Maybe it was because of differences in the ways the two studies measured children’s development.

It is also possible that high fish consumption in the Seychelles, while exposing children to relatively high levels of mercury, also improves brain development. In other words, the nutritional value of the fish itself could overwhelm any negative effect of mercury.

That would resonate with the arguments of many in the fish industry.

“Fish is good for you,” said Randy Ray of the Pacific Seafood Processors Assn. of Mercer Island, Wash. “Pretty much most of the ocean is really, really safe. You’ve got some local water bodies which are an issue and some fish at the top of the food chain that are an issue but, by and large, chow down on the shrimp.”

What is beyond dispute is this: Mercury warnings for U.S. lakes, rivers and coastal regions increased 115% from 1993 to 2001. There are almost 2,000 mercury-in-fish warnings on various water bodies in 44 states.

Mercury is a naturally occurring element found in the Earth’s crust and sometimes exposed by volcanic eruptions, mining and other disturbances. More commonly, it makes its way into the environment when oil- and coal-fired power plants burn those fossil fuels, separating the mercury from the carbon and spewing it into the atmosphere.

Rain washes the metal from the air onto land and into waterways, where it settles and is eaten by microorganisms that turn it into methylmercury. Small fish then eat the organisms, absorb the methylmercury and are eaten by larger fish.

The methylmercury accumulates, making its way up the food chain in ever-increasing concentrations until people consume it.

If there is a consensus among scientists, it is that the most vulnerable population by far is the very young, especially still-developing fetuses. Like lead, mercury can wreak havoc on the rapidly multiplying cells of a growing brain, leading later in life to decreased intelligence, lowered coordination and impaired hearing.

“It’s the chemical that can push the child over the edge,” said Dr. Philip Landrigan, chairman of the Mount Sinai medical school’s Department of Community and Preventive Medicine.

According to a National Academy of Sciences report issued in 2000, 60,000 babies born each year might be at risk of neurological damage because of mercury, and that will probably mean more kids who struggle in school and need remedial classes or special education.

Findings like these have led British authorities to recommend that pregnant women abstain from eating fish.

In Japan, where per-capita fish consumption far outpaces that in the United States, researchers are beginning to investigate the effects of chronic, low-level mercury exposure. Studies have repeatedly shown elevated mercury levels among the Japanese, as well as medical problems in some people. But a Health Ministry spokesman said the Japanese government does not issue any consumption guidelines for specific foods.

In the United States, the FDA held a three-day conference in July and suggested that pregnant women limit the canned tuna they eat to two six-ounce cans a week -- if that is the only source of fish in their diets -- and to only one can if they eat other fish. The agency zeroed in on canned tuna because it is by far the most popular seafood Americans eat. There is no evidence that it is potentially any worse than many other fish. Canned tuna has more mercury than scallops or catfish, for example, but less than fresh tuna or lobster, according to a May 2001 FDA report.

The FDA advises pregnant women not to eat swordfish, shark, king mackerel or tilefish (also known as golden or white snapper), the species known to contain the highest levels of mercury.

But this is not enough for some doctors and activists, who say that because of gaps in our knowledge about mercury, the standards are little more than educated guesses. They lament that the FDA stopped monitoring mercury in fish four years ago -- “so that it could look at all the data that had accumulated,” said spokesman Mike Herndon. He did not say why monitoring stopped during the evaluation.

“Without an adequate mercury-monitoring program for seafood, it is virtually impossible for pregnant women and women of reproductive age to make informed dietary choices,” said Dr. Ted Schettler of Physicians for Social Responsibility.

U.S. Sen. Edward M. Kennedy (D-Mass.) has also been among those pressing for a stronger FDA effort.

The Centers for Disease Control says one in 10 women have potentially dangerous levels of mercury in their blood. Wendy Moro was one of them.

Moro, 40, of Burlingame, Calif., wanted to get healthy, so she ate fish: Tuna for lunch. Crab salad for a snack. Sushi for dinner. But the more fish she ate, the sicker she felt.

For years, she visited doctors, neurologists, endocrinologists, general practitioners, even a psychologist who assured her that she wasn’t crazy -- just sick.

Finally Moro visited Hightower, the San Francisco internist who tested, among dozens of other items, the mercury levels in Moro’s blood.

What she found was three times the medically safe levels spelled out by the CDC.

“I was shocked,” Moro said. “We’re told to eat fish; we’re told it’s great for you.”

And that, to experts like Dr. Jae Hong Lee, former senior medical policy analyst at the National Center for Policy Research for Women and Families, is the crux of the problem. Not enough has been done to determine the effects of mercury or the amount of mercury in fish -- or to publicize the fact that there is reason for concern. “The public knows about the many health benefits of eating fish,” Lee said. “But few know about the risk of eating too much.”