For Kerry Davies ’11, fish is no longer a staple in her diet. Not being much of a frequent fish eater, Davies has not consumed seafood in months.
“I don’t think I’ve eaten any fish in about six months or so,” said Davies. “I’ve never really been a fan of fish. I’ve definitely never been a fan of tuna. I think the last thing I ate was fillet of sole.”
Yet what Davies, and many others, may not realize is that despite the fact she ate that fish nearly six months ago, remnants of her meal will still be swimming through her bloodstream up to three years later.
“Mercury stays in the body for two to three years after eating contaminated fish,” said David Brown, professor of environmental ethics. “The biggest problem with mercury is that it has such a long half life.” When someone eats contaminated fish, Brown said, it takes about three months for half of what has been released into the bloodstream to clear out of the system. After another three months, half of that remaining amount will have cleared out. “Multiply the three months by nine and that will give you a good estimate of when your blood mercury levels should be safe again,” said Brown.
Dr. James Biardi, assistant professor of biology, explained that mercury has a half-life, which is why it remains in the bloodstream so long.
“Between one and 10 percent of the initial ingested dose would be found in the bloodstream, and therefore potentially expose a fetus,” said Biardi. “Half life is about 50 days, meaning that half the dose would be cleared by then, three-quarters by 100 days and seven-eighths by 200 days.”
“Certainly mercury in excess is problematic, in particular in pregnant women,” said Gary Nelson, Director of the Student Health Center. “I believe in general, the recommendation is to try to limit one’s intake of fish which potentially have high mercury content which tend to be the bigger fishes, like tuna.” Bryan Davis, general manager of Sodexho Dining Services, said that precautions are being taken both at the Stag and the cafeteria to make sure no harmful fish is being consumed by the campus community.
The FDA and EPA, however, continue to emphasize the benefits of fish as part of a healthy, balanced diet. The advisory recommends varieties such as shrimp, canned light tuna, salmon and catfish, which contain the least amount of mercury.
According to the EPA, fish and shellfish are low in saturated fat and contain omega-3 fatty acids, which could contribute to a child’s proper growth and development while maintaining heart health.
According to a 2004 press release from the Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA), daily or frequent intake of fish and shellfish may be harmful to one’s health, especially for women.
The FDA and EPA announced in a joint consumer advisory on methlymercury in fish and shellfish that they encourage women who may become pregnant, pregnant women, nursing mothers, and young children to reduce their intake of such fish.
“The FDA and EPA want to emphasize the benefits of eating fish – consumers should know that fish and shellfish can be important parts of a healthy and balanced diet,” said the advisory. “They are good sources of high quality protein and other essential nutrients; however, as a matter of prudence, women might wish to modify the amount and type of fish they consume if they are planning to become pregnant, pregnant, nursing, or feeding a young child.”
“I rarely eat fish here at school,” said Carolyn Marino ’11. “But when I’m at home I eat it quite often. Since my mom is a nurse, I’m aware of the levels of mercury in fish, which is why we try to limit ourselves to two meals a week, because while there is this potential threat, it’s still good for you because of the omega-3.”
Dr. Jessica Davis, assistant professor of chemistry, also reinforces the fact that one can still safely eat fish each week. “For most people the risk is not great – there are great benefits to eating fish, and pretty much all fish contains some mercury,” said Davis. “Two servings of fish a week is the FDA recommendation.” However, a high level of mercury could be harmful to an unborn baby or young child’s developing nervous system.
“Recently, in my maternity class, we learned about the mercury risks in newborns and the possible effects on their neurological development,” said Emily Verger ’09, a nursing major. “Specifically how pregnant and breast feeding women need to stay away from big fish, especially tuna.” “For women of childbearing years,” said Davis, “it is recommended to take a break from certain types of fish one year before becoming pregnant to allow the level that accumulates in the body to lower naturally as mercury can cause nervous system defects, including the brain, in the developing fetus or child.”
In a recent consumer report, the FDA explained that mercury is release into the atmosphere annually by naturally degassing from the Earth’s crust and ocean or by human activity, making mercury vapor easily transported and deposited on land and water.
“Fish absorb methyl mercury from water as it passes over their gills and as they feed on aquatic organisms,” said the FDA. “Larger predator fish are exposed to higher levels of methyl mercury from their prey.” “Methyl mercury binds tightly to the proteins in fish tissue, including muscle. Cooking does not appreciably reduce the methyl mercury content of the fish,” according to the report.
“New England is the most concentrated, contaminated area on the planet when it comes to mercury,” said Brown. “Mercury falls from the air, depositing itself on the leaf litter. When it rains or the snow melts, the residue from the leaves is washed away to the rivers where it becomes part of the sediment.”
According to a report done by PBS in February 2004, a new analysis by the Environmental Protection Agency revealed that ‘about 630,000 children are born each year at risk for lowered intelligence and learning problems caused by exposure to high levels of mercury in the womb,’ nearly doubling the previous EPA estimate.
Yet most women do not realize that the more mercury they take in now, the more likely their consumption is to still have an effect on children they may want to have in the future.
“With such a long half life, a young woman could eat fish today and then two to three years down the road decide to have a baby, and that child may still feel the effects of the mercury in the mother’s system,” said Brown.
“I had no idea about any of this until now,” said Verger. “I guess I’m going to have a problem with all that tuna I used to eat [in high school]. Good thing I’ve stopped.”
“I think that people know there are issues surrounding tuna and mercury but I think a lot of people don’t really know what,” Verger continued. “If the problems associated with mercury were publicized more, it may give people more incentive to watch what they eat.”
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