News Coverage
Mercury advisory becomes hooked to other concerns
Published April 17, 2004
Political struggles over the Bush administration's air pollution regulations and the fate of Pacific sea turtles are drawing attention again to the problem of mercury in fish, as the federal Food and Drug Administration finally amended its longstanding consumer advisory to include canned tuna. One thread in all of this is longline fishing, in which the hooks used to catch tuna, swordfish and other large species sometimes snag sea turtles as well. Moreover, the fish caught by longliners store mercury in their tissues, and sources of that potentially harmful element include coal-burning power plants.
In late March, the FDA announced that expectant and nursing mothers, women who may become pregnant, and young children should eat no more than one six-ounce can of albacore tuna per week to limit their exposure to mercury in fish.
That advisory was the upshot from years of debate over whether canned tuna should be included on the mercury advisory list. The decision didn't sit well with environmental groups, who sought an even more conservative warning.
"It's been three solid years, and we're hearing no substantive improvements. ... They've fallen so far short of what the public needs," complained Jane Houlihan, vice president for research with the Environmental Working Group, a Washington, D.C.-based activist organization that's critical of the mercury standard.
FDA officials say their mercury limits still give an eightfold margin of safety for the population most sensitive to the organic traces of mercury, called methylmercury, that are found in some fish. Mercury can have harmful effects on the neurological development of fetuses and young children, and the FDA recommends that mothers and children avoid altogether swordfish,shark, tilefish and king mackerel.
The dispute is really over how wide the margin of safety should be set, said Randi Thomas of the U.S. Tuna Foundation, a tuna industry association. The government's reference point is set "for the most sensitive part of the population," Thomas said.
Other groups contend the albacore limit should be one can a month - or none at all - to widen the margin.
"Six ounces of albacore is probably pushing it," but it's a long-needed improvement to the health advisory, said Dr. Michael Gochfeld, a mercury researcher at the Environmental and Occupation Health Sciences Institute in Piscataway.
In a report published in December, Gochfeld and professor Joanna Burger of Rutgers University found canned albacore white tuna they obtained from a central New Jersey supermarket contained mean mercury levels of 0.407 parts per million.
In comparison, canned light tuna contained a mean mercury level of 0.132 ppm. The simple lesson, Gochfeld said, is for mothers and children to "choose light over white."
Some organizations, such as the Environmental Working Group and Environmental Defense, have created their own online "seafood calculators" on their Web sites to show consumers how to determine even more restrictive fish intake based on their weight, sex and other personal factors.
Mercury in the food chain
Warnings on tuna present a public health dilemma: Fish is a prime, low-fat source of protein, omega-3 oils, minerals and vitamins, and eating more of it is one way Americans can stave off obesity and cardiovascular disease,dietary experts say.
In its pure state, mercury is a silvery, liquid metal. Uncontained, it will bead and roll across a laboratory countertop, a testimony to its ancient name: quicksilver. In the environment, mercury emitted from nature's volcanoes and humanity's coal-burning power plants falls into oceans and lakes.
Once in the water, mercury is converted by bacteria into an organic form called methylmercury, a more toxic form. As bacteria are eaten by grazing organisms, which are eaten by other animals, and big fish eat little fish,methylmercury becomes more concentrated as it moves up aquatic food chains. Although mercury traces in the water are minute, the bioaccumulation process multiplies methylmercury many times over in the tissues of top-end predators, whether they're Atlantic swordfish or Pine Barrens pickerel,according to state and federal studies.
Studies of human health effects have yielded mixed results, but they tend to reassure federal food regulators that their mercury limits are adequate. A University of Rochester study tracked a group of mothers and children in the Seychelles, an island nation in the Indian Ocean where swordfish is nearly as much a staple as canned tuna is in America. Despite elevated mercury levels in the women, the scientists reported they could not link the mercury to any neurological ill effects in their children.
A competing study of families on the Faroe Islands far north of Scotland documented some below-average results among children on neurological tests. Environmental activists tend to cite that study more, while critics have questioned its statistical correlations and possible confounding factors such as polychlorinated biphenyls (PCBs), another chemical contaminant in whale meat consumed by Faroese.
"If everyone was eating 15 pounds of swordfish a year, there might be a problem," said Gef Flimlin, an agent with the Rutgers Cooperative Extension Service who works with commercial fishermen and shellfish growers. "If you look at how many kinds of fish you can buy in New Jersey, there's probably 80 or more. If you wanted fish for dinner all the time, you could eat something different every night and not eat the same thing for months." Still, "people react very negatively. I think they overreact to negative discussions about seafood," said Flimlin, who is organizing a seafood safety conference in June at Rutgers University to bring together scientists, nutrition and health experts and the news media.
Different agendas pushed
The tuna debate is tied into other environmental issues, said Thomas of the tuna industry foundation.
"All of these issues are mixed up. It's not just the fishing issues. It's the air pollution coming from utilities. These (activist) groups go round and round and keep building it up," she said.
The federal Environmental Protection Agency has been battered by accusations that its own scientists' advice on limiting mercury emissions from power plants was trumped by political pressure from the utilities industry. Mercury from American power plants is just a part of worldwide mercury emissions, so skeptics question how much it contributes to mercury contamination in the ocean environment, which also has a number of natural sources such as volcanic vents.
But the state Department of Environmental Protection says domestic air emissions are directly linked to mercury levels in freshwater lakes and streams; mercury levels are particularly elevated in Pine Barrens chain pickerel, for example. DEP officials have gone to court seeking to limit what drifts here from Midwestern power generator stacks.
Under terms of an earlier lawsuit settlement with the Natural Resources Defense Council, the federal EPA must meet a court-ordered deadline for new air regulations before the end of this year. It proposes a system that it says would reduce mercury emissions 70 percent by 2018, while allowing utilities to trade air pollution limits between newer and older plants. However, EPA advisers in January told agency Administrator Mike Leavitt that "the cap and trade program, as proposed, may not address existing hot spots and may create new local hot spots for mercury, disproportionately impacting local communities."
Meanwhile, the mercury issue has been taken up by sea turtle preservationists, who picket and even sue California supermarkets over point-of-sale mercury warnings at fish counters. On its Web site at www.seaturtles.org, the Sea Turtle Restoration Project ties its goal of stopping longline fishing to getting consumers to buy less swordfish and tuna.
That has some in the fishing industry saying the long-running mercury issue has been subordinated to other agendas.
"It seems to be a multipronged attack on the fishing industry in general,and longlining in particular, out there," said Nils Stolpe of the Garden State Seafood Alliance, a New Jersey commercial fishing industry group. Some environmental groups oppose the fishing gear used to catch swordfish and tuna, and when recent publicity campaigns tied those fish to mercury,"it's the same organizations behind it," Stolpe said. "With the exception of king mackerel, the other fish are species that the enviros have big problems with."
The seafood industry had always lobbied against adding canned tuna to the advisory, arguing that the risk for mercury exposure was relatively low, but the risk high that Americans would be turned off from eating fish altogether. New Jersey fishermen have not detected any direct effect on their sales from the recent flurry of contaminant reports, Stolpe said. "The steak tuna market is different because people don't eat enough of it to be affected. Swordfish is different. People don't eat a lot of it, and the price moves around a lot," Stolpe said. "People don't eat tuna steaks the way they eat canned tuna, which is more of a staple."
Over the past decade, government advisories on mercury gradually have become more conservative. The agency's current position is that pregnant women and women who may become pregnant should avoid eating certain kinds of larger,long-lived fish that tend to accumulate higher methylmercury levels in their tissue than other species.
Swordfish, shark, king mackerel and tilefish should be avoided by childbearing women, and that caution should extend too for women who are nursing infants, and to very young children whose central nervous systems are still developing, the FDA says.
As for other fish, the FDA recommends that women and children in the risk group eat on average up to 12 ounces per week - or two to three servings a week, based on typical serving sizes.
The advisory also cautions about eating fish caught from local freshwater streams and lakes. In some states, including New Jersey, elevated mercury levels in freshwater fish such as pickerel have led state health authorities to issue their own health advisories about consuming those catches. Commercially farm-raised freshwater fish, such as tilapia, trout and catfish, can be included in the basic guideline for 12 ounces per week, the FDA says.
"One food does not a diet make. The key with all these advisories is not to eat one thing to the exclusion of others," said Don Schaffner, a food science professor at Rutgers University's Cook College in New Brunswick.