NEW YORK: Recent laboratory tests performed for The New York Times found so much mercury in tuna sushi that a regular diet of even two or three pieces a week at some restaurants could be a health hazard for the average adult, based on guidelines set out by the Environmental Protection Agency.
Eight of the 44 pieces of sushi The Times purchased from local restaurants and stores in October had mercury levels so high that the Food and Drug Administration could take legal action to remove the fish from the market.
Although all the samples were gathered in New York City, experts believe similar results would be observed elsewhere. "Mercury levels in bluefin are likely to be very high, regardless of location," said Tim Fitzgerald, a marine scientist for Environmental Defense, an advocacy group that works to protect the environment and improve human health. Most of the stores and restaurants in the survey said the tuna The Times had sampled was bluefin.
In 2004, the Food and Drug Administration joined with the Environmental Protection Agency to warn children and women who may become pregnant to limit their consumption of certain varieties of canned tuna because the mercury it contained might damage the developing nervous system. Fresh tuna was not included in the advisory. The tuna sushi in The Times sample contained far more mercury than is typically found in canned tuna.
Over the past several years, studies have suggested that mercury may also cause health problems for adults, including an increased risk of cardiovascular disease and neurological symptoms.
Dr. P. Michael Bolger, a toxicologist who is head of the chemical hazard assessment team at the Food and Drug Administration, said the agency was reviewing its seafood mercury warnings. Because it has been four years since the advisory was issued, he said, "we have had a study under way to take a fresh look at it."
Tuna samples from the restaurants Nobu Next Door, Sushi Seki, Sushi of Gari and Blue Ribbon and the food store Gourmet Garage all had mercury in excess of one part per million, the "action level" at which the FDA can take food off the market. (In recent years, the FDA has rarely, if ever, taken any tuna off the market.)
The European Union can take tuna and other predatory and long-lived fish off the market at the same mercury concentration, one part per million.
Both Drew Nieporent, a managing partner of Nobu Next Door and Andy Arons, an owner of Gourmet Garage, were shocked by the Times' findings.
"I'm startled by this," said Nieporent. "Anything that might endanger any customer of ours, we'd be inclined to take off the menu immediately and get to the bottom of it."
Arons, whose stores stock yellowfin, albacore and bluefin, depending on the available quality and price, said, "We'll look for lower-level-mercury fish. Maybe we won't sell tuna sushi for awhile, until we get to the bottom of this."
At Blue Ribbon Sushi, Eric Bromberg, an owner, said he was aware that bluefin tuna had higher mercury concentrations. For that reason, he said, the restaurant typically tells parents with small children not to let them eat "more than one or two pieces."
Scientists who performed the analysis for The New York Times said they had been "frankly surprised" at the results and had run the tests several times to be sure there was no mistake in the levels of methylmercury, a form of mercury tied to health problems.
"No one should eat a meal of tuna with mercury levels like those found in the restaurant samples, more than about once every three weeks," said Dr. Michael Gochfeld, professor of Environmental and Occupational Medicine at the Robert Wood Johnson Medical School in Piscataway, New Jersey, who analyzed the sushi for the Times with Dr. Joanna Burger, professor of life sciences at Rutgers University.
The work was done at the Environmental and Occupational Health Sciences Institute, in Piscataway, New Jersey, a partnership between Rutgers and the Robert Wood Johnson Medical School. Gochfeld is a former chairman of the New Jersey Mercury Task Force. He also treats patients with mercury poisoning.
More than half of the restaurants and stores surveyed sold sushi with so much mercury that eating just six pieces a week would exceed the amount the Environmental Protection Agency says can be safely consumed by an adult of average weight, which the agency defines as 154 pounds, 70 kilograms. People weighing less are advised to consume even less mercury.
In general, tuna sushi from food stores was much lower in mercury. These findings reinforce results in other studies showing that more expensive tuna usually contains more mercury because it is more likely to come from a larger species that accumulates mercury from the fish it eats.
In the Times survey, 10 of the 13 restaurants said at least one of the two tuna samples purchased had been bluefin. (Itis hard for anyone but experts to tell whether a piece of tuna sushi is bluefin by looking at it.) By contrast, other species, like yellowfin, bigeye and albacore, generally have much less mercury. Several of the stores in the Times sample said the tuna in their sushi was yellowfin.
"It is very likely bluefin will be included in next year's testing," said Dr. Bolger of the FDA. "A couple of months ago, FDA became aware of blue fin tuna as a species Americans are eating."
Studies have found high blood mercury levels among people eating a diet rich in seafood. According to a 2007 survey by the New York City Department of Health and Mental Hygiene, the average level of mercury in New Yorkers' blood is three times as high as the national average. The report found especially high levels among Asian New Yorkers, especially foreign-born Chinese, and people with higher incomes.
The report noted that Asians tended to eat more seafood and speculated that wealthier people favored certain fish, like swordfish and bluefin tuna, with higher mercury levels.
The city has warned children and women who are pregnant or breastfeeding not to eat any fresh tuna or Chilean sea bass or several other fish it describes as "too high in mercury."
Kate Mahaffey, a senior research scientist in the office of science coordination and policy at EPA who studies mercury in fish, said she was not surprised by reports of high concentrations.
"We have seen exposures occurring now in the United States that have produced blood mercury a lot higher than anything we would have expected to see," she said. "And this appears to be related to consumption of larger amounts of fish that are higher in mercury than we had anticipated."
Many experts believe the government's warnings on mercury in seafood do not go far enough. "The current advice from the FDA is insufficient," said Dr. Philippe Grandjean, adjunct professor of environmental health at the Harvard School of Public Health and head of the Department of Environmental Medicine at the University of Southern Denmark. "In order to maintain reasonably low mercury exposure you have to eat fish low in the food chain, the smaller fish, and they are not saying that."
Some environmental groups have already sounded the alarm. Environmental Defense, the advocacy group, says no one should eat bluefin tuna.
Others take a less absolute position. "I like to think of tuna sushi as an occasional treat," Gochfeld said. "A steady diet is certainly problematic. There are a lot of other sushi choices."
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