News Coverage
Scientists worry that mercury dangers mimic deadly lead
Published January 26, 2005
Laura Pugliese believes in a healthy lifestyle. She teaches yoga, uses organic shampoos and lotions, and eats lots of fruits and vegetables.
Last summer, Pugliese, 28, who had been trying to get pregnant, had her hair tested for mercury, a toxic pollutant that interferes with brain development in the fetus. The results showed the mercury level in her body was 50 percent over the Environmental Protection Agency's safety level.
"I was trying to be healthy and stay away from all those hormones and pesticides," said Pugliese, who blames her mercury level on a high-fish, low-meat diet. "Instead, I got mercury - not such a good tradeoff."
Scientists have long known that people like Pugliese who eat lots of fish tend to have higher mercury levels in their bodies, but it's only recently that the seriousness of the public health problem has become widely recognized.
Some scientists are calling mercury "the new lead." As with lead, the more scientists study mercury, the more they find subtle damage to the brain at lower and lower levels of exposure.
It also appears that so many people carry mercury contamination in their bodies, the pollutant may be impairing the intelligence and brain functioning of the population at large. And, as with lead, brain damage from mercury is permanent.
Most at risk is the developing fetus. The EPA estimates that one in every six children born in the United States - about 630,000 children annually - is exposed in the womb to mercury levels that exceed the current safety level. This places children at risk for an average IQ loss of 1.5 points, learning disabilities and other cognitive impairments.
Even that number may be an underestimate. Dr. Philippe Grandjean, an adjunct professor at the Harvard School of Public Health who has studied the effects of prenatal mercury exposure for nearly two decades, said the EPA should consider cutting in half the amount of mercury it estimates a person can safely ingest each day.
Recent, more sophisticated analyses of data from a major mercury study in the Faroe Islands of the North Atlantic show that significantly lower levels of maternal exposure to mercury than was previously understood can cause unsafe mercury concentrations in the fetus. The Faroes study was the primary basis for the EPA's current safety level.
"The message to EPA is you used the wrong number ... the number is only half as high," said Grandjean, who led the Faroes study. "Now shouldn't you go back and reconsider your reference dose?"
Other scientists, including at least two members of a landmark National Academy of Sciences committee on mercury, also said the EPA should rethink its safety calculations.
Potential harm to the fetus isn't the only issue. Dr. Jane Hightower, who practices internal medicine in San Francisco, has documented 350 cases of adults and children who suffered hair loss, headaches, difficulty in concentrating and other symptoms. Their common link was that they ate fish frequently.
"These are people who are not deterred by the price," Hightower said. "They do not like bones in their fish, they do not like a fishy flavor, and so they eat the large predators. They were told fish was good for them, but they weren't told about the contaminants."
Meanwhile, studies indicate that low doses of mercury can have harmful cardiovascular effects in adult men.
And research by wildlife biologists with the U.S. Geological Survey has found that some bird species suffer effects such as weakened eggs and dead offspring when fed amounts of mercury that are as low as a tenth of the human dietary limit.
Agency scientists are monitoring mercury-related studies as they are published in scientific journals, but there has been no move to re-evaluate the safety level, EPA official Denise Keehner said.
The EPA's safety limit "is the most restrictive standard in the world and was designed to ensure that even pregnant women who regularly eat large quantities of fish - which is a very small number of people - are not at risk of consuming mercury levels that could harm their children," said David Burney, executive director of the U.S. Tuna Foundation.
The growing evidence of risk prompted the American Medical Association to call on the Food and Drug Administration to consider requiring stores to post mercury warnings wherever canned tuna and other fish are sold.
The FDA and the EPA warn pregnant women and children to limit their consumption of canned albacore tuna to no more than one can per week. (Canned "light" tuna is generally lower in mercury and can be eaten more frequently than albacore tuna.)
Advocacy groups such as the Environmental Working Group say their calculations show that eating more than one can of albacore per month can be risky for some women.
Several states - including Maine, Minnesota, Wisconsin and Washington - also recommend stronger limits on seafood or freshwater fish consumption than the FDA and the EPA.
The controversy has left millions of Americans like Pugliese grappling with the quandary of how to get the health benefits of eating fish - which are naturally rich in omega 3 fatty oils that are good for the heart and fetal brain development - and still protect themselves and their children from mercury.
U.S. consumption of canned tuna has dropped 15 percent in the last few years and shrimp has replaced tuna as the nation's No. 1 seafood. Restaurant chains such as Morton's Steakhouse and Red Lobster have removed such high-mercury species as swordfish from their menus.
"This is a Band-Aid approach to the real problem," said Dr. Katherine Shea, a North Carolina pediatrician and environmental health consultant for Physicians for Social Responsibility, "which is that the fish shouldn't be polluted in the first place because they are such excellent sources of important nutrients."
Mercury exists naturally in the environment, but levels have risen 200 percent to 500 percent since the start of industrialization two centuries ago, primarily because of pollution from coal-fired power plants.
Microbes at the bottom of bodies of water transform the pollution into methylmercury, the most toxic form of mercury, and the contaminant works its way up the food chain. Longer-lived predatory fish like shark, swordfish and larger species of tuna tend to have the highest mercury concentrations.
President Bush has proposed reducing mercury emissions 70 percent by 2018, although an EPA analysis indicates that the cap-and-trade portion of the plan could delay reductions until 2025. Critics say the technology exists to achieve similar or greater reductions by 2010.