Confession: I’m a nutritional Girl Scout, the kind of shopper who stands in the aisle squinting at food labels. When I was pregnant, I knew I was supposed to limit my intake of certain kinds of fish—no shark, swordfish, mackerel, or tuna—because they contain higher levels of mercury, which can harm developing fetuses.
So when I interviewed actress Daphne Zuniga about her battle with mercury poisoning (“From Anger to Activism,” March), it elicited my sympathy but not surprise. She was a pescatarian and ate tuna nearly every day before her diagnosis, exposing herself to high levels of mercury.
But then she mentioned something else. “Oh, and mercury can be in your dental fillings, too.” I had a mouthful of metal fillings placed over the course of 30 years. By sheer coincidence, one of my teeth cracked a few weeks after the interview, dislodging part of my filling with it. It wasn’t until I was getting the tooth fixed that it occurred to me: Was that broken filling something to worry about? Had mercury been released into my system?
Mercury is a naturally occurring element found in vapors emitted by volcanoes (heads up, Iceland!), incinerators, factories, and coal-burning plants. From there it enters our water and food supply. For the last century, it’s been used as a preservative, such as Thimerosal, found in some vaccines, and as an antifungal in paint and pesticides.
What makes mercury especially nasty is that it’s a neurotoxin. When it enters the body, it attacks the brain and nervous system, targeting and killing certain neurons, which can result in headaches, blurred vision, fatigue, forgetfulness, depression, and changes in personality, such as irritability and sudden shyness.
Usually, warnings about mercury in fish are targeted to pregnant women—the metal crosses the placental barrier, showing up in the brains of developing fetuses and, eventually, in breast milk and young children. A recent study conducted in Spain confirmed the link between consuming large amounts of mercury-infected fish to memory and language problems in kids. In adults, long-term mercury exposure impairs immunity, and kills beneficial bacteria, leading to yeast overgrowth and digestive problems. It also displaces essential minerals, causing everything from anemia to irregular heartbeat. And it’s been linked to lowered progesterone levels, which can result in miscarriage and infertility. Even scarier? Mercury toxicity is cumulative. Once the metal gets in your system, symptoms can build over time, as levels gradually increase.
Even if I didn’t consider myself a “sick” person, I did have mercury fillings, and I had spent a lifetime indulging in spicy tuna rolls and Niçoise salads. I couldn’t help wonder: Was my body humming at its best or being dogged by a lifetime of exposure to a heavy metal?
Where mercury lurks
For Americans, the most common sources of mercury exposure are fish and dental amalgam—or “silver”—fillings, which contain between 40 percent and 50 percent mercury.
Mercury released into the atmosphere works its way into our water system through rain and snow runoff, and it bio-accumulates as it works its way up the food chain. That’s why the biggest predatory fish, like sharks and tuna, have the highest levels: They’ve eaten thousands of contaminated fish that have eaten thousands of contaminated fish.
Then it hits our plate. The Environmental Protection Agency (EPA) has set the maximum daily intake of mercury at 0.1 mcg/kg of body weight. That’s roughly equivalent to eating one can of white albacore tuna every 10 days. More than that and you may be at risk for serious health issues.
“I call it ‘fish fog,’ ” says Jane Hightower, MD, author of Diagnosis: Mercury: Money, Politics, and Poison (Island Press, 2008). “I’ve literally had hundreds of patients come into my office knowing they’re not feeling right but not knowing what’s wrong.”
Although the EPA and FDA can’t agree on “safe” mercury levels, neither considers moderate chunk light–tuna consumption risky for healthy adults—a claim that’s come under fire in light of high-profile cases of mercury poisoning in celebrities like Jeremy Piven and Daphne Zuniga, who point to fish intake as the source of their exposure.
Fish my have gotten all the publicity, but amalgam dental fillings—which contain mercury as a bonding agent—are a major potential source of exposure. A study of autopsies done by the Karolinska Institute in Sweden showed that people with amalgam fillings had higher levels of mercury in their brains and kidneys.
Approximately 85 percent of the American public has one or more amalgam fillings. And more than 100 million new fillings are placed each year. The American Dental Association and FDA argue they’re safe. Anti-amalgam dentists say they aren’t. According to amalgam opponents, mercury vapors can be released into to the body during filling placement or removal, or when fillings are cracked (like mine), heated, abraded, or frequently exposed to acidic juice or hot coffee (guilty of that, too).
Despite studies to the contrary and the recent ban of amalgams in Norway, Denmark, and Sweden, the FDA stated in July 2009 that the levels of mercury vapor released “are not high enough to cause harm in patients.” The agency maintains that only a small percentage of the population is mercury sensitive to the point of experiencing severe fatigue, weight loss, or sleeplessness after a filling is put in.
“We know it harms people, and it always has,” Hightower says. “It penetrates every cell in the body. There is no safe level.”
Ready for the silver lining? Use of amalgams has dropped 50 percent in the last seven years, in large part due to advances in the durability and affordability of alternatives like resin composites. But for those of us with older amalgams still intact, the issue is confusing: Should we have them removed?
According to California dentist Tom McGuire, DDS, the answer is yes. “Your immune system will be stronger without mercury in your body,” says McGuire author of The Poison in Your Teeth (Mercury Free Publications, 2008). “Mercury makes it more difficult for the body to function normally. It’s a cumulative poison. If you don’t remove the source, it’s going to negatively affect your health.”
Steps to reduce mercury exposure
- Assess the risk. The more fillings you have and the longer you’ve had them, the greater your potential exposure. The same goes for fish—the more you eat, the more mercury can accumulate. If you think you might be exposed, look for mercury toxicity’s more subtle symptoms: headaches, memory loss, stomach upset, a metallic taste in your mouth, joint and muscle aches, and fatigue.
- Get tested. If you have several risk factors, your general practitioner, internist, or naturopath can determine how much mercury is in your system with a urine, hair, blood, or stool test. Most healthcare practitioners opt for a combination of the four, in addition to a patient history, examination, and exploration of alternative diagnoses.
- Focus on fish. If you eat fish often, switch to low-mercury sources, such as wild salmon, domestic crab, anchovies, and tilapia. Restrict your intake of large predators like albacore tuna and mackerel to three times or less per month. Download a portable, wallet-size card with safe fish picks from the Natural Resources Defense Council (nrdc.org).
- Rethink your fillings. Amalgam fillings present a trickier fix. It’s important to ask your dentist about a safe amalgam removal protocol, and insist he use a rubber dam during removal to isolate the tooth and any mercury particulates, as well as secondary suction and supplemental oxygen, so you are not breathing in mercury vapors. If your dentist isn’t open to discussing his philosophies and procedures regarding amalgams, find another dentist who is. Try the International Association of Mercury Safe Dentists or McGuire’s comprehensive website, which has a searchable database of practitioners (dentalwellness4u.com).
- Detoxify. Severe mercury poisoning may require pharmaceutical chelation therapy—the administering of a man-made amino acid called ethylene diamine tetraacetic acid (EDTA), which binds, or chelates, to the heavy metal so it can be excreted through urine. But EDTA can cause kidney failure, bone marrow depression, cardiac arrhythmias, respiratory arrest, and shock. Also, add natural chelators to your diet. Cilantro binds heavy metals, and the sea vegetable chlorella moves the resulting substance out of the body, says Brenda Watson, CNC, author of The Detox Strategy (Free Press, 2009). Because any kind of chelation triggers a loss of critical amino acids and minerals, consult your healthcare provider before starting a regimen. Dietrich Klinghardt, MD, a neurobiologist at The Comprehensive Medical Center in Kirkland, Washington, recommends eating protein, minerals, fatty acids, essential amino acids, and fluids to help replenish what the body loses excreting mercury (see “Natural Detox Essentials,” above).
- Speak up. Become a voice for toxin-free dentistry and an advocate for clean air and water. Choose a dentist who practices mercury-free dentistry, make sure that your seafood choices support healthy fisheries, and take steps in your everyday life to help combat pollution.
As for me? Although I haven’t been tested, I’ve taken commonsense steps. I choose tuna as a treat, not a staple, and instead, rely on wild-caught salmon (occasionally) for healthy protein and omega-3s. I’ve also made an appointment with a dentist to gradually replace all those old silver fillings, because for me, having mercury in my mouth is a little too close for comfort.
By Cara McDonald