Mercury Rising

Vogue Magazine, May 2009

Seafood is a staple of a healthy diet, but determining what’s safe (and green) to eat is getting trickier.  By Bronwyn Garrity.

The Whole Foods fish guy is idling, his gloved hands poised for action above rows of fish with lovely, unwieldy descriptions like MSC-CERTIFIED, CHILEAN SEA BASS, FILET, WILD, FIJI.  While my eight-month-old wriggles around in the grocery cart, I’m scanning the labels, attempting to translate each ID into a concept I can understand: safe to eat or not safe to eat.

Like other supermarkets, Whole Foods doesn’t provide mercury concentrations in the fish they sell.  They do post the warning that young women and children should avoid shark, swordfish, king mackerel, and tilefish, but I already know to skip those mercury-laden species.  It’s choosing among the 37 other available options, from clams to grouper, that concerns (and confuses) me.  I have a three-year-old daughter, a baby who’s still breast-feeding, and the amped-up anxiety level of a new mom.

As I pause to lament today’s absence of wild salmon – my go-to-fish that is low in mercury but high in beneficial omega fatty acids – the fishmonger steers me towards LAKE TROUT, FRESH, WILD, GREAT LAKES.  He describes it as “oily, like salmon.”  Oily equals omegas, I think, and the Great Lakes sound pristine.  I also remember seeing trout listed as a lower-mercury fish on the Food and Drug Administration’s fish-advisory Web site.  I order up half a pound.

But at dinner later, Carys, my three-year-old, happily munches on the fish, I start to feel panicky.  This trout is so big, so fleshy.  Size was a variable I forgot at the store – bigger fish typically contain more mercury.  Now, on her dainty plate, it’s impossible to ignore.  I tell her to wait while I run upstairs, I Google MERCURY, LAKE TROUT, GREAT LAKES to panic-inducing results.  Lake trout is apparently not the same trout I remember from the government’s list.  I spot one page on the Environmental Protection Agency’s Web site discussing the “endocrine-disrupting effects of mercury in lake trout project,” while another delves into the “subcellular distribution of mercury in liver of lake trout.”  In a flash, I am back downstairs, scraping our dinner into the trash.

I can’t help feeling a little rattled.  Even accounting for maternal overprotectiveness, the avalanche of evidence about the dangers of mercury in seafood is undeniably scary.  Every new study links it to something I don’t want: joint pain, hearing and vision problems, memory loss, fertility problems, immune disorders, gum disease, gastrointestinal disorders, lowered IQ and developmental problems in children, and even heart attacks – the number one killer of American women.  Yet while it has long been my right as an American shopper to know the precise amount of riboflavin in my breakfast cereal, I am left to play craps with the level of neurotoxins in my fish.

Every new study links mercury to something  I don't want... immune and gastrointestinal disorders, developmental problems...

Unfortunately, that level may be increasing.  Emissions from the world’s coal-fired power plants and other human pollution – along with smaller releases from natural sources like volcanoes – work in sync with mercury’s persistent nature to make an otherwise perfect food depressingly flawed.  Once released, mercury cycles through the environment – evaporating and then drifting back down, much of it landing in oceans and lakes, where it is absorbed by small plants and animals.  In a process known as biomagnification, fish accumulate mercury more rapidly than they excrete it, and every fish up the aquatic food chain contains more than the one it just ate.  According to the EPA, long-lived predators like tuna, pike, bass, shark, and swordfish can have levels of mercury up to 10 million times greater than the surrounding water.  And when we make them part of our regular diet, we contain even more.

Several recent investigations point to a startling spike in the amount of mercury in tuna, the most popular fish in America.  One 2008 study, by Oceana and the Mercury Policy Project, found levels in fresh and frozen tuna steaks to be nearly double the FDA’s averages, lifting tuna into the range of the Do Not Eat club.  Shockingly, a full third of sushi tuna samples tested from restaurants around the country exceeded the FDA’s “action level,” at which point the fish can be yanked from the market (that level is currently one part per million, or 1ppm).  Even reliably lower-mercury fish, like tilapia, may have higher concentrations than FDA data show.  Oceana’s study found the farm-raised fish still tested low (0.8ppm), but eight times higher than the 0.01 cited by the FDA.

Horrifying.  But what finally tips me into paralysis is the fact that for every study detailing the ravages of mercury, I find one recommending fish, especially to women in their childbearing years.  Even with mercury’s dangers, many experts continue to believe that the benefits of some fish make the risks worth taking.  Like mercury’s good twin, long-chain fatty acids from oily cold-water fish like salmon, anchovies, albacore, some sardines, and yes, lake trout are our most potent natural source of the fatty acids DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid), which appear to be nothing short of biological gold.  N-3s, as they’re known in scientific circles, have the ability to penetrate nearly every cell in our bodies, offering protection against heart disease and depression.  They also have the opposite effect of mercury in babies, boosting neurological development.

For every study detailing the ravages of mercury, I find one recommending fish to women in their childbearing years

So what, exactly, is a health-conscious fish lover to do?  The government is of frustratingly little help.  The FDA and EPA published a joint advisory in 2004, “What You Need to Know About Mercury in Fish and Shellfish,” which endorses eating up to twelve ounces of “lower”-mercury fish each week, identifying shrimp, canned light tuna, salmon, pollack, and catfish as popular choices. (The advisory notes that six of the twelve ounces can be canned albacore).  Unfortunately, with the exception of the albacore and salmon, these fish are all relatively low in n-3s.  More important, the recommendations are based on the rosy assumption that mercury levels in fish have been static.  Commonly eaten fish like anchovies, American lobster, skate, and herring were last tested in the late seventies.  Even FDA levels of mercury in skipjack tuna – a species often found in “canned light,” – are based on tests from fifteen years ago.  Nor, it seems, can you count on the government – or the fishmongers – to toss out the catch of the day if it exceeds the FDA’s “action level.”

But while the people I’ve trusted to make sure my food is safe can’t be relied on to test the food I eat for mercury, I soon learn there is a way to answer the question of how much mercury I’ve consumed – and, potentially, to help me avoid any more mid-dinner Google-fueled freakouts.  My breakthrough comes after a friend refers me to Soram Singh Khalsa, M.D., an internist known for his interest in environmental contaminants, particularly the health effects of mercury.  Three weeks after the trout scare, I arrive in his posh Beverly Hills office.  A Yale grad and associate physician in the Division of Internal Medicine at Cedars-Sinai Medical Center in Los Angeles, Khalsa explains that there is currently no practical way for a fish lover like me to test how much mercury is in every fillet I buy.  But, he adds, it is quite easy to test how much mercury is in me.  For the cost of a pound of good ahi ($25), I can add a mercury test to my regular blood work and see, definitively, whether all the time and energy scrutinizing descriptions and studies and government Web sites is actually doing any good.

Just how much mercury it's safe to have floating around in your bloodstream has long been the subject of debate.  There was even a time when doctors believed the heavy metal promoted health.  Abraham Lincoln took daily mercury tablets (flavored with rose petals and honey), and over the years, it has been used to treat such maladies as syphilis and diaper rash.  But in modern times, ever since mercury was conclusively identified as a neurotoxin that attacks the brain and central nervous system, the amount considered safe to have in our bloodstream has come down and down.

While I’m waiting to hear back about my own blood mercury, I call the EPA and ask spokesman Dale Kemery what the agency currently considers a safe level for women of childbearing age.  The answer: “EPA doesn’t set a safe blood level.”  Instead, they provide consumption guidelines to determine the amount of mercury a person can ingest every day for the rest of her life “without expectation of adverse effect.”  Kemery explains that eating up to twelve ounces of fish weekly (about two restaurant-size meals) with mercury levels no higher than .12ppm will keep me in the EPA’s range.  If I go by the FDA’s recorded mercury levels, I can eat up to twelve ounces of cod (.095), clams (below 0.01), spiny lobster (.09), and Pollack (.041), but should modify my servings of bass (.219), snapper (.189), halibut (.252), Northern/American lobster (.310), grouper (.465), Chilean sea bass (.386), and the infamous lake trout (.3) among other, higher-mercury species.

EPA doesn't set a safe blood level... instead they provide consumption guidelines

I eventually do get to a number – though no one will use the word safe.  Blood mercury is measured in “micrograms per liter.”  And the government figures I’d wind up with a level of no more than 5.8 if I followed EPA recommendations of eating twelve ounces of fish like salmon and canned tuna.  (It also assumes that the government estimates of how much mercury those fish contain are accurate, not understated.)

But, as I discover when I go out with friends, it’s easy to find people with blood mercury levels well above the EPA’s limit of 5.8.  Everyone seems to know someone -  in fact, the greater your income and level of education, the higher your risk for elevated mercury.  Margot Schupf, a 37-year-old New Yorker and associate publisher at HarperCollins, was eating tuna sushi twice a week as well as tuna salads once or twice a week, when she found her level to be 11, or almost twice the EPA’s number.  And Ann Dynes, a 62-year-old retired lawyer, reached a blood mercury level of 48 by eating swordfish and ahi steaks once a week and tuna salads for lunch.

Kathryn Mahaffey, Ph.D., formerly the EPA’s leading mercury scientist but now retired, explains to me that eating “even a little bit of the big four” (swordfish, shark, tilefish, king mackerel) will get you “quite a dose of mercury.”  But she is quick to point out that you can get just as much from other fish if you eat a lot more of them.  “It’s not just a case that you worry about a few fish.  You worry about a quantity eaten overall,” she cautions.  Philippe Grandjean, Ph.D., a Harvard University and University of Southern Denmark environmental-health professor on whose research the EPA set is recommendations, agrees.  “Perhaps some people are more sensitive than others.  But better safe than sorry… and you can get lots of great seafood with only traces of mercury. “  Grandjean recommends eating small (and ideally younger) low-mercury fish like salmon, haddock, and shrimp just once or twice a week.

Grandjean’s conservative advice reflects a growing belief among some scientists that the EPA’s level of 5.8 is too high, especially if you are considering becoming pregnant.  The current dose was set in 2001, when the scientific community believed a fetus’s mercury level matched that of its mother.  Studies have since shown that mercury concentrations in fetal blood are, on average, 70 percent higher than in the mother’s – meaning a woman with a blood level higher than 3.4 is putting her baby at an increased risk of neurological problems.  According to Mahaffey, one in ten young American women has a blood level in this range.

The findings have sparked Harvard’s Grandjean to argue for stricter rules.  “If you use the best current science, then you end up with a limit that is 50 percent below what the EPA says,” he tells me.  For now, the EPA stands by its recommendations, though the agency says it will review them when more evidence is available. 

In the meantime, the Obama Administration is likely to take a tougher line on mercury exposure than we’ve seen in years.  As a senator, Obama introduced a bill to ban the export of mercury from the United States, and in February, the administration reversed two Bush-era policies by calling for a treaty to slow global pollution and seeking new regulations on emissions from U.S. power plants.  Daniel Reifsnyder, the deputy assistant secretary of State for environmental and sustainable development, called mercury “the most important global chemical issue facing us today that calls for immediate action.”

It turns out that eating lower-mercury fish is one way to keep your own environmental footprint lighter, too.  As Laura Pagano, an attorney with the Ocean’s Program at the National Resources Defense Council (NRDC) sees it: “We are not hunting down and eating the Siberian tiger anymore, and we really shouldn’t be eating the magnificent top predators in the ocean.”  Look for the Marine Stewardship Council (MSC) icon, a blue circle with a check through it (and the mysterious mark on the aforementioned sea bass).  “It is the only symbol we have to tell us“ our food is being harvested sustainably, says Pagano, though the MSC does not rate farms, which produce one in three fish on the market.

A few weeks later, Khalsa phones with my blood results.  I am shocked – and relieved.  It’s just one microgram per liter, well below EPA recommendations.  Was it higher a few month ago when I was eating seafood several times a week?  Almost certainly – mercury’s half-life in the blood is 70 days just 42 for nursing moms like me), and I’ve cut way back in the last few months.  Regardless, the test results, backed up by weeks of research (Googling and otherwise), has given me a sense of confidence at the fish counter – which I admit I’m visiting less frequently these days.  Regardless of my dinner choice, I get my omegas through molecularly distilled fish oil (EPA and DHA) supplements.  And when I do eat seafood, I ask whether the whole fish – when it was still swimming – could fit on my plate.  The little guys don’t live long enough to accumulate many contaminants.  And turning them into dinner once a week won’t put too much of a dent in the dwindling fish populations.  It’s a solid rule of thumb courtesy of Jane Hightower, M.D., another doctor pushing for greater awareness of mercury in seafood.  As she says: “If it’s bigger than something you can drag in on a line, you might want to contemplate letting it live.”