LIANE HANSEN, host:
Dentists have long used silver fillings, or amalgams, to restore decayed teeth. An amalgam filling is about half mercury and half other metals. The Food and Drug Administration says there's no evidence that they're harmful, but some people are concerned about the health effects from fillings that include mercury. Nancy Cohen from member station WNPR reports that a Connecticut law intended to reduce mercury in the environment could lead to the first state ban on silver fillings.
NANCY COHEN reporting:
The law bans the sale of many items that contain mercury, such as some light switches and thermometers, because of its toxicity in the environment. But Connecticut has yet to decide whether the ban includes amalgam fillings.
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COHEN: A public hearing on the issue was held last May. Among the speakers was 60-year-old Freya Koss. She held up a photograph of herself with one eye half closed, taken after she had one amalgam filling removed and replaced with another.
Ms. FREYA KOSS (Consumers for Dental Choice): For three years, my eyelids drooped, I lost my equilibrium and I had double vision. And through my own research, I discovered that I was acutely poisoned by mercury during the dental process.
COHEN: Koss says neurologists diagnosed her with various autoimmune diseases, including multiple sclerosis. She believes her fillings were the cause and had them removed. Koss now works for the Washington, DC-based group Consumers for Dental Choice, which is lobbying to get amalgams banned in the US.
Frederick Eichmiller directs a research center for the American Dental Association. He says the mercury in amalgams--which is bonded to silver along with copper, tin and zinc--should not be compared to an equivalent amount of elemental mercury.
Mr. FREDERICK EICHMILLER (Research Center Director, American Dental Association): Well, mercury, when it's combined with these other metals, has entirely different properties than mercury as it stands alone or as you'd know it in a thermometer. That's why we can use it as a safe filling material.
COHEN: Like elemental mercury, amalgams do emit mercury vapor. Eichmiller says it's absorbed into the body and can be measured in the urine, but those mercury levels are low.
Mr. EICHMILLER: Well below, far below, any of the levels that we know will elicit any type of adverse response. You know, it's been estimated that it would take almost 500 fillings to be able to elicit the smallest response out of the most sensitive patients.
COHEN: A 2004 government-sponsored review of past studies on amalgam found a correlation between the amount of mercury in a person's urine and the amount of amalgam fillings in the mouth. A similar correlation was found when measuring the amount of mercury in the placenta of pregnant women with amalgams. But the review did not found an association between health risks and exposure to mercury from fillings.
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COHEN: Connecticut dentist Mark Breiner, who's on the board of Consumers for Dental Choice, is placing a composite filling in a patient's mouth, a tooth-colored filling made of plastic and glass.
Dr. MARK BREINER (Board Member, Consumers for Dental Choice): Bite and rub. How's that feel?
Unidentified Patient: Good.
COHEN: Breiner hasn't put an amalgam filling in a patient's mouth in 30 years. He says studies done on animals--including one done at the University of Calgary, which placed amalgams in sheep--shows they're unsafe.
Dr. BREINER: That mercury from the fillings went to all the tissues and organs.
COHEN: The American Dental Association refutes the relevance of this study to people; Breiner disagrees. He says any amount of mercury, including the amount from amalgams, is poisonous to humans.
Dr. BREINER: Mercury comes out in an extremely toxic form as a vapor, comes off of the fillings. It really can cause almost anything because of its lethality.
COHEN: Four years ago, Connecticut's Department of Public Health threatened to take Breiner's license away. The department claims he told patients that removing amalgams would alleviate disease. Breiner says he never gives this type of advice, but he has agreed to have patients sign a form stating there's insufficient scientific evidence to support that view.
Toxicologist Tom Clarkson, of the University of Rochester School of Medicine, says mercury from amalgams is absorbed into the bloodstream and can get into most tissues, including the brain. But, he says, epidemiological studies have found no evidence that exposure to mercury vapor from amalgams will cause or exacerbate disease.
Mr. TOM CLARKSON (University of Rochester School of Medicine): We're able to say, with a high level of confidence, is that most people will not show any toxic effects. There is one effect of amalgam that we do know about, and that is that a limited number of people are allergic to mercury. So when the first amalgam filling is placed in the mouth, these people react immediately. And that's the only, as far as I'm concerned, clear-cut established effect of amalgam.
COHEN: Mark Breiner says Connecticut has banned some products that contain mercury because it's dangerous to the environment. He says what's toxic to the environment doesn't belong in the mouth.
Dr. BREINER: You don't even have to have any science; all you have to have is common sense. If I take a filling out of a patient's mouth, that filling has to be treated as hazardous waste. I cannot throw that in the garbage. I can be fined and arrested, you know. And before it goes in the mouth, it's treated as a toxic substance, so I mean, it makes no sense.
COHEN: Scientists are continuing to investigate the safety of amalgams, including Tom Clarkson, who's part of a research team investigating whether amalgams pose a risk to children.
Mr. CLARKSON: Just as a member of this team itself, I cannot emphatically say that they're are no health risks. If there are health risks, they're very low, but we're trying to find them, if they exist at all.
COHEN: Some countries have recommended against placing amalgams in certain patients. No state restricts the use of amalgams. For NPR News, I'm Nancy Cohen in Hartford.
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