I am what I ate
By Katharine Mieszkowski
Salon Magazine online
Nov. 17, 2004
Too bad Superfund is bankrupt, because I recently discovered that I'm a toxic waste dump. Yes, I'm a walking, talking contamination site, liable at any moment to freak out my friends, colleagues and acquaintances by announcing that my mercury pollution level exceeds federal health guidelines for women my age.
In fact, trace amounts of the neurotoxin are in the very fingernails that I'm using to type these words. And you too, may be swimming with mercury, depending on how much tuna or other big carnivorous fish you like to gobble.
Curious? You can find out your own mercury levels by sending a few strands of your hair to a testing lab. A few weeks before the presidential election, environmental advocates at Greenpeace offered to test me as part of a study on mercury contamination conducted by the Environmental Quality Institute at the University of North Carolina-Asheville.
I agreed, and shortly thereafter my own mercury test kit arrived in the mail. I enlisted a colleague to play the role of medical assistant/hair stylist. She donned the enclosed plastic gloves to cut a sample from the back of my head close to the scalp. I managed to cough up an adequate sample under her scissors, despite worrying about what it would do to my look -- because the inch or so of hair necessary for the test has to come from the part of your coiffure closest to the scalp. That's so the hair tested will measure more recent mercury exposure, unlike the older hair at the tips of your locks.
A few weeks later I found out I was contaminated. And I'm not alone. In preliminary results, the study found that 21 percent of potentially child-bearing women exhibited mercury levels that exceed Environmental Protection Agency guidelines.
Scientists for the EPA estimate that some 600,000 kids born each year are at risk because of their mothers' mercury levels, since mercury levels in a newborn's umbilical cord were found to be 1.7 times the level in the mother's blood.
The largest manmade source of mercury pollution is the coal-fired power plant, which puts the toxin squarely in the middle of energy politics. Environmental groups tried to make mercury pollution in fish an issue in swing states during the presidential election. MoveOn.org ran an ad criticizing the Bush administration's lax approach to curbing mercury pollution. Meanwhile, the tuna industry seized on recent data from the Centers for Disease Control that suggest overall contamination levels of American women could be lower than previously measured, and proclaimed there is nothing to worry about.
But women in their reproductive years aren't likely to put much trust in the self-interested propaganda of the tuna industry. Mercury can put a developing fetus or nursing child at risk for brain damage. Children born with high levels of mercury can have learning disabilities, lower IQ scores, and behavioral problems like sluggishness. The expectant mom need not have any of symptoms
In August, the EPA announced that 48 out of 50 states have issued advisories about eating fish caught in their rivers and lakes because of pollution from mercury and other toxins. Over 75 percent of those fish advisories are due to mercury. According to the EPA, most mercury in American adults comes from eating contaminated fish, whether it's caught locally or bought in the supermarket.
We're not talking anchovies and sardines here. It's the big carnivorous fish, like tuna, high on the food chain, that "bioaccumulate" a substance known as methyl mercury in the course of eating loads of smaller fish.
Mercury pollution thus has a dual-pronged effect. Poor people who fish for their own food in mercury-laden waters are at risk, but so are the wealthy who aren't price sensitive when it comes to what they perceive as a healthy diet rich in sushi, halibut, ahi tuna, swordfish and seabass. This leads to a paradox: The better off you are, the worse off you are.
"Higher economic status and education level appear to be risk factors," Dr. Jane M. Hightower and biostatistician Dan Moore of California Pacific Medical Center wrote in a study of affluent people in the San Francisco Bay Area, some of whom complained of symptoms like fatigue, inability to concentrate and memory loss.
Personally, I don't eat all that much fish. When I sent off for the mercury test, I just thought it would be intriguing to see what was there. I also thought it amusing that all that was necessary for the test was a lock of my hair.
But hair apparently is a trusty barometer: "With your hair growing, it's basically tracking the chemicals in your body continuously," explains Michael W. Murray, a scientist with the National Wildlife Federation. "Once you eat a fish meal, a little bit of it is going to be removed with time, and some of it is going to come out in your hair. Hair analysis seems to work pretty well for mercury."
"Technically, what you're measuring is the amount of mercury that your body has been able to get rid of in the last three or four months," explains Richard Maas, the director of the Environmental Quality Institute, which did the testing on my hair sample. "When that came in there's no way to say."
"You may not think of your hair as being dead cells, but it really is," adds Kathryn Mahaffey at the EPA, who has conducted analysis of methyl mercury transfer from mother to child. "These are simply excretion products in the body, if you're speaking metabolically, although it may not make the stylists happy. It's just a natural phenomenon. For example, birds get rid of mercury by putting it in their feathers, bears in their fur."
Although I was sure I was going to end up with an ugly bald patch on the back of my skull, which I planned to blame on the coal industry or environmental hysteria, depending on my test results, cutting my hair for the sample didn't noticeably change my look, and after I mailed it to the lab just before the election, I promptly forgot about it. I really wasn't worried.
But a week after President George W. Bush had been ushered back into office with larger Republican majorities in both the House and Senate, all but assuring the continuation of his laissez-faire pollution policies, I received a letter at home informing me that I am in fact over the limit that the EPA and National Academy of Sciences recommend. My results came back as 1.08 micrograms of mercury per gram of hair, just over the threshold of 1 part per million that's considered safe.
"If your laboratory results are between 1 and 11 [micrograms of mercury per gram of hair] your mercury hair level is above the recommended limit," the enclosed Interpreting Mercury Hair Results sheet informed me. "You could be at elevated risk if you are pregnant, planning to become pregnant or nursing a baby. We recommend that you avoid fish that may contain elevated levels of mercury and also reduce consumption of fish with low to moderate levels of mercury (please see attached list)."
When I decided to throw myself into this highly politicized morass as a test subject, I had no special reason to believe that I had any more of this toxin in my body than the rest of you sushi-eating, ahi-tuna-steak-scarfing types. I am not a habitual angler, casting my fly into waters hot with the contaminant. I don't think I even eat enough fish to meet the American Heart Association's recommendation of eating fish twice a week to build a healthy heart. If the government announced there was mercury in peanut butter, I'd be willing to believe I'm aglow with the stuff. But tilefish and shark? I don't think that I've ever eaten either of those.
The Bush administration, flush with the glow of a new term, is poised to issue new guidelines for regulating mercury pollution in March 2005. Environmentalists are not sanguine about the prospect. If a track record is any prediction of future behavior, this administration, they believe, is far more likely to listen to its close friends in the coal industry, who are fighting any increased regulation, instead of the record-breaking 600,000 public comments that the government has received about the proposed rule.
Rationalizing that I was just .08 over the limit, so it wasn't really that big a deal, I called Maas, of the Environmental Quality Institute, which did the testing. But he told me: "If you have a level above 1, it's definitely a cause for concern."
He explained that it's statistically probable that my contamination came from fish, although there are other possible, if less likely, sources, such as the silver amalgam filling I have in one tooth, or the traces of mercury used as a preservative in some medical shots, such as flu shots. But the most probable source is fish, and therefore the easiest way to try to lower my level is to change the fish I eat.
Here's how the toxin gets into fish: When coal burns, it releases mercury that gets turned into gas, Maas says. As it cools, the mercury turns into aerosol droplets, which can travel hundreds of miles before settling onto the ground or water. In water, it settles into the sediment at the bottom of rivers and lakes.
"The bacteria in the sediment methylate this mercury and turn it into methyl mercury to make it less toxic to themselves," Maas says. "That's a problem, because methyl mercury is fat soluble." That makes it harder for creatures that consume it to excrete it, according to Maas, since the mercury gets stored in lipid and muscle tissue.
What happens next is the process that makes methyl mercury more concentrated in a shark than, say, a worm. "When burrowing worms or insect larvae consume sediments, they get that methyl mercury in them, and then it gets biomagnified up the food chain. Then, maybe a crawfish eats that insect larva, and a small fish eats that crawfish, and a larger fish eats the small fish," Maas says. "Each time all the methyl mercury is passed up the food chain. Each trophic level will then have a methyl mercury level 10 times higher than the one below it. That's why by the time you get to the sports fish and large fish that we actually consume, those levels are quite high."
The state of California requires grocery stores to post warnings about mercury contamination in the fish they sell, although they don't always comply.
But all the estimates, recommendations and warnings are based on averages and approximation. You never know exactly what level is in the sample on the end of your fork. I may not think that I eat a lot of fish, but the fish that I happened to eat during the months represented by the hair sample could have been especially contaminated, leading to my high reading:
"There's a bit of a Russian-roulette element here. You may go to a sushi bar, and get a fairly decent slab of tuna, and you may get a hot mercury-rich piece," says Kert Davies, a spokesperson for Greenpeace.
Mercury pollution from power plants is not regulated at the federal level, although some states like Massachusetts, New Jersey and Wisconsin have imposed their own measures. But federal regulations are now being formed. The National Wildlife Federation and the Public Interest Research Group argue that under the Clean Air Act, 90 percent of the mercury pollution from those plants should be cleaned up by 2008. Under the same law, the government is already successfully implementing cuts on mercury pollution from waste incinerators. Environmentalists say only corporate self-interest is preventing the same thing from happening with power plants
Under the legislation the Bush administration calls Clear Skies, only 70 percent of that mercury would be cleaned up, and it might take as long as until 2025.
"We're expecting them to reintroduce Clear Skies as soon as the new Congress comes in, in January, because of the election results," says Olivia Campbell, national campaign coordinator for the National Wildlife Federation. Sen. James M. Inhofe, R-Okla., known for calling "manmade global warming" "the greatest hoax ever perpetrated on the American people" on the floor of the Senate, plans to reintroduce the bill. With a friendlier Senate, it has a better chance of passing, and the EPA is expected to release its mercury regulations by March. Although mercury does occur naturally from geological formations, like volcanos, some 70 percent of the emissions in the United States, according to the Ocean Conservancy, come from burning coal.
To be fair, the methyl mercury that apparently was speared by my fork or chopsticks can't all be pinned on Bush, given the global nature of the fish supply. We might have to clean up the whole world to make it safe for future mothers to eat swordfish and shark again. But the Bush administration has opposed attempts by European delegates to the United Nations to create a global protocol to control mercury.
So, instead of trying to regulate methyl mercury out of the food supply, we're stuck with trying to avoid the pollution at an individual level. The Environmental Protection Agency offers these guidelines for what women of reproductive age should and shouldn't eat. (They offer no guidelines for men, the traditional logic being that if you protect the hypothetical unborn fetus, which can tolerate only the lowest levels, it's likely that everyone else in a given family is getting safe levels, too.)
The EPA guidelines suggest that if you're concerned about mercury, you leave big predatory fish, like shark, swordfish and tilefish, out of your diet completely. You're also supposed to limit your intake of other fish and shellfish to those that eat lower on the food chain and are therefore lower in mercury, such as salmon and shrimp, to about 12 ounces -- about two average meals -- a week.
Albacore tuna is typically higher in mercury than light canned tuna, so limiting albacore to once a week is also advised. But environmental watchdog groups challenge those guidelines as not aggressive enough, suggesting that they subject women and their fetuses and young children to too much risk, while pandering to the tuna industry. Environmental groups offer their own, more conservative, recommendations.
The gross irony of all this wrangling over which fish has more or less mercury is that government scientists are fearful that consumers, grossed out by mercury pollution, may just shun fish in general. Why are they alarmed? Because, when fish is not subtly poisoning you, it's very good for you.
"If your level is higher than you consider desirable, reduce the amount of mercury you're taking in your diet by changing the types of fish that you're eating," Mahaffey from the EPA told me, diplomatically. "We do think that fish is good for you overall, so we really recommend that people select fish that are lower in mercury." But she admits that it's a hard message for consumers to understand: "It's a complicated risk message because for years we've been telling people that fish are good for you. They're recommended to help in the prevention of coronary heart diseases, and also a lot of weight-reduction diets have recommended these. Yet, as we learn more about the levels of contamination it's pretty clear that we have to be selective in the types of fish you eat."
Some studies even suggest that the well-known heart-health benefits of the omega-3 fatty acids in fish can be canceled out by mercury. "If you're eating fish every day, you're not really getting much benefit from the fatty acids," says the National Wildlife Federation's Murray. "The effects of the contaminants seem to really overtake the benefits that you're getting at those higher levels."
Mahaffey recommends salmon, anchovies and shrimp, which all have "decent amounts" of omega-3 fatty acids and relatively low mercury levels. And she tells consumers to eat less "steaklike" fish. In other words, eating fish that themselves eat lower on the food chain is your best bet.
The good news, from my perspective, is that subjects who cut their fish intake in some studies, like Hightower's, have seen drops in their measurable mercury levels in just a few months. I'll get back to you with my next set of test results. Let's hope I can report I'm out of the toxic zone and still have some hair left by the end of this.
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