High Mercury Levels Are Found in Tuna Sushi
Recent laboratory tests found so much mercury in tuna sushi from 20 Manhattan stores and restaurants that at most of them, a regular diet of six pieces a week would exceed the levels considered acceptable by the Environmental Protection Agency.
Sushi from 5 of the 20 places had mercury levels so high that the Food and Drug Administration could take legal action to remove the fish from the market. The sushi was bought by The New York Times in October.
“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, N.J.
Dr. Gochfeld analyzed the sushi for The Times with Dr. Joanna Burger, professor of life sciences at Rutgers University. He is a former chairman of the New Jersey Mercury Task Force and also treats patients with mercury poisoning.
The owner of a restaurant whose tuna sushi had particularly high mercury concentrations said he was shocked by the findings. “I’m startled by this,” said the owner, Drew Nieporent, a managing partner of Nobu Next Door. “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.”
Although 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 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 women who might become pregnant and children 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. Most of the tuna sushi in the Times samples 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, did not comment on the findings in the Times sample but said the agency was reviewing its seafood mercury warnings. Because it has been four years since the advisory was issued, Dr. Bolger said, “we have had a study under way to take a fresh look at it.”
No government agency regularly tests seafood for mercury.
Tuna samples from the Manhattan restaurants Nobu Next Door, Sushi Seki, Sushi of Gari and Blue Ribbon Sushi and the food store Gourmet Garage all had mercury above one part per million, the “action level” at which the F.D.A. can take food off the market. (The F.D.A. has rarely, if ever, taken any tuna off the market.) The highest mercury concentration, 1.4 parts per million, was found in tuna from Blue Ribbon Sushi. The lowest, 0.10, was bought at Fairway.
When told of the newspaper’s findings, Andy Arons, an owner of Gourmet Garage, said: “We’ll look for lower-level-mercury fish. Maybe we won’t sell tuna sushi for a while, until we get to the bottom of this.” Mr. Arons said his stores stocked yellowfin, albacore and bluefin tuna, depending on the available quality and the price.
At Blue Ribbon Sushi, Eric Bromberg, an owner, said he was aware that bluefin tuna had higher mercury concentrations. For that reason, Mr. Bromberg said, the restaurant typically told parents with small children not to let them eat “more than one or two pieces.”
Koji Oneda, a spokesman for Sushi Seki, said the restaurant would talk to its fish supplier about the issue. A manager at Sushi of Gari, Tomi Tomono, said it warned pregnant women and regular customers who “love to eat tuna” about mercury levels. Mr. Tomono also said the restaurant would put warning labels on the menu “very soon.”
Scientists who performed the analysis for The Times ran the tests several times to be sure there was no mistake in the levels of methylmercury, the form of mercury found in fish tied to health problems.
The work was done at the Environmental and Occupational Health Sciences Institute, in Piscataway, a partnership between Rutgers and the Robert Wood Johnson Medical School.
Six pieces of sushi from most of the restaurants and stores would contain more than 49 micrograms of mercury. That is the amount the Environmental Protection Agency deems acceptable for weekly consumption over a period of several months by an adult of average weight, which the agency defines as 154 pounds. People weighing less are advised to consume even less mercury. The weight of the fish in the tuna pieces sampled by The Times were 0.18 ounces to 1.26 ounces.
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, which accumulates mercury from the fish it eats. Mercury enters the environment as an industrial pollutant.
In the Times survey, 10 of the 13 restaurants said at least one of the two tuna samples bought was bluefin. (It is 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 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,” Dr. Bolger of the F.D.A. said. “A couple of months ago F.D.A. became aware of bluefin tuna as a species Americans are eating.”
A number of studies have found high blood mercury levels in 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 higher than the national average. The report found especially high levels among Asian New Yorkers, especially foreign-born Chinese, and people with high incomes. The report noted that Asians tend to eat more seafood, and it speculated that wealthier people favored fish, like swordfish and bluefin tuna, that happen to have higher mercury levels.
The city has warned women who are pregnant or breast-feeding and children not to eat fresh tuna, Chilean sea bass, swordfish, shark, grouper and other kinds of fish it describes as “too high in mercury.” (Cooking fish has no effect on the mercury level.)
Dr. Kate Mahaffey, a senior research scientist in the office of science coordination and policy at the E.P.A. 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,” Dr. Mahaffey 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 F.D.A. is insufficient,” said Dr. Philippe Grandjean, adjunct professor of environmental health at the Harvard School of Public Health and chairman 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 sounded the alarm. Environmental Defense, the advocacy group, says no one, no matter his or her age, should eat bluefin tuna. Dr. Gochfeld said: “I like to think of tuna sushi as an occasional treat. A steady diet is certainly problematic. There are a lot of other sushi choices.”