Quotes of the Day

A couple of weeks ago I took a pair of scissors and clipped a thatch of hair from the back of my head. I did not do this lightly — much like petroleum, my hair is an increasingly scarce resource, and I'm doing my best to conserve it. But I was taking part in a Sierra Club–sponsored test for mercury contamination in people, and levels of the toxic metal can be detected through hair. So I taped the small sample I could spare inside an envelope and sent it off to the University of Georgia, which was doing the actual testing. And then I pretty much forgot about it.

So I was more than a bit surprised when an express letter arrived at my home from the University of Georgia a few days later, with a message from Lisa Liguori, the scientist who runs the testing lab there. It turned out that my mercury levels were more than twice the government-recommended safety limit. I wasn't exactly a walking thermometer, but I had a surprising amount of the stuff in my blood and body.

Fortunately, for a man, mercury contamination isn't considered a significant health risk — and my levels are still well below the point at which harm would likely occur. But women who are pregnant or want to get pregnant, as well as very young children, are a different story; those groups are more vulnerable to mercury contamination. The reason is that mercury is a neurotoxin that impairs brain development in young children, either directly or through a pregnant or nursing mother. According to the Environmental Protection Agency (EPA), as many as 1 in 12 American women have enough mercury in their bodies to put a baby at risk, which means that as many as 300,000 infants a year may face an increased risk of learning disabilities associated with in utero exposure to mercury. "For kids that young, their brains are developing and vulnerable to this," Liguori says.

But here's what I want to know: How was I exposed to mercury? I don't exactly handle the metal in my job, so I probably wouldn't be directly exposed to it. But I do eat seafood — a lot. I probably have a tuna sandwich twice a week for lunch, and I eat sushi — a habit I picked up during my reporting stint in Japan — almost as often. I always thought those choices were healthy — and indeed, fish like tuna are a valuable source of protein and omega-3 fatty acids, which are good for the heart. But those same fish can have high mercury levels. "Seafood is the main route of exposure for Americans," says Liguori.

But don't blame the beleaguered fish directly for the problem. We may be exposed to mercury via some seafood, but beyond naturally occurring mercury in the environment, much of the pollution begins with coal, which can contain mercury. Nearly every lump of coal we burn for energy releases some of its mercury into the atmosphere — and since we burn a lot of coal, we release a lot of the toxin. (Between 1999 and 2005 — the most recent years for data — mercury emissions from power plants increased more than 8%, from 49 tons to 53 tons.) From there, some of the mercury ends up in the aquatic environment — rivers, lakes or oceans — where bacteria transform it into organic methylmercury, which is digestible by animals but also more toxic. The methylmercury steadily moves up the food chain, bioaccumulating in large predatory fish or in especially long-lived species — which is why big hunters like the tuna or swordfish tend to have higher levels. In 2008, there were 16.8 million acres of lakes and 1.3 million miles of river under advisory for mercury levels, an increase of 19% and 42%, respectively, since 2006. "The big fish accumulate the mercury from the little fish, and then it ends up on your plate," says Mary Anne Hitt, deputy director of the Sierra Club's national coal program.

Disturbingly, there's no way to remove mercury before we eat fish because it binds to their muscle. And when we digest that muscle, the mercury load stays with us. Still, the answer is not to abandon seafood because of mercury fears; that would almost certainly leave you worse off, because you'd lose the cardiovascular benefits of eating fish. "For the general population, there is convincing evidence that the cardiovascular benefits greatly outweigh the risks," says Harvard medical professor Dariush Mozaffarian, co-author of one of the most comprehensive studies on fish consumption. "Eating a variety of fish and other seafood at least twice per week, preferably oily and dark-meat fish, is a great target."

Whatever your risk tolerance, the good news is that you can rapidly reduce your mercury levels through some simple changes in your diet while still eating plenty of seafood. Instead of chunky white tuna, you can choose light tuna, which has lower mercury levels, or try seafood like salmon, pollock or shrimp. Eating lower on the marine food chain — think sardines and mussels — is a good way to minimize mercury exposure too — and it also happens to be more sustainable for sea life. "Before I got pregnant, I lowered my mercury level by 70% in approximately two months by changing my habits while still eating seafood twice a week," Liguori says.

That's a relief — though if I end up getting pregnant, I will have bigger health worries than my mercury level. But it's wrong that anyone should be put at any risk, however uncertain, simply for eating seafood. Instead, we need to stop mercury pollution at its source. That's what the EPA is finally poised to do: after years of delay, the agency recently proposed the first regulations for mercury emissions from coal plants, along with arsenic and other toxic pollutants. Those rules would cut mercury emissions by about 91%, along with emissions of arsenic, chromium and other toxic pollutants. According to the EPA, the new rules would also help limit fine particulate pollution, which would prevent some 17,000 premature deaths and 11,000 heart attacks a year, in addition to reducing mercury contamination. (Fine particulate pollution has been linked to heart disease.) The utility industry is expected to fight the regulations, which would cost about $10 billion a year to implement but could provide as much as $100 billion a year in public health benefits. "People might think that coal-plant pollution is something that only affects you if you live right next to one," says Hitt of the Sierra Club. "But the mercury issue shows we can all be affected by coal." And I've got the test results to prove it.

• Bryan Walsh
• An environmental journalist is surprised to learn that his mercury levels exceed the U.S. government-recommended safety limit