BETHESDA -- There is no hard evidence that the mercury in dental fillings poses any health threat despite concerns raised last year by a Canadian study and a report on "60 Minutes," a government-sponsored panel of experts said yesterday.
While chewing releases mercury vapor from amalgam fillings, the kind found in the mouths of 200 million Americans, the amounts are tiny "and do not cause verifiable adverse effects on human beings," said a statement issued yesterday by the 14-member panel, meeting at the National Institutes of Health campus.
Panel Chairman William D. McHugh, director of the Eastman Dental Center at the University of Rochester, said there was no reason for patients to have their amalgam fillings removed -- as many sought to do after the airing of the "60 Minutes" report on the controversy in December. And panel members said patients, including pregnant women, had no need to fear having new or replacement amalgam fillings installed.
"I had two amalgam fillings [renewed] last week and I've been fine, up to now," Dr. McHugh said during a news conference.
But not enough research has been done, the panel also said, into the possible health risks tied to the use of amalgams and other less commonly used filling materials, including gold, ceramics and plastics. All those materials, or compounds containing them, can leach minuscule amounts of toxic substances.
Dr. Gordon B. Shelton, a dentist with offices near Towson, welcomed the panel's chief finding, saying that he talked about two dozen of his patients out of having their amalgam fillings removed and replaced with non-amalgam materials after seeing "60
"They created a terrible panic," he said. "It was really a disservice to the public in general."
Yesterday's statement came at the end of a three-day technology assessment conference sponsored by the NIH and the National Institute of Dental Research.
The conference panel unanimously approved the final report. But Dr. Michael Kashgarian, a panelist and professor of pathology at Yale, stressed the need for more research into all dental filling materials, and sounded more cautious than most of his colleagues. "We should probably take another look. We should not just assume on the basis of history that these things are safe."
The panel also recommended that the manufacturers disclose the ingredients in dental filling materials and that the information be referred to in each patient's dental records. The Food and Drug Administration should also create a program for reporting and investigating cases of "adverse reactions" to dental materials, the panel said.
Medical specialists agree that mercury poisoning can cause a wide variety of symptoms, including arthritis and depression, and a variety of neurological and autoimmune disorders, including multiple sclerosis. The question is whether minuscule doses, such as those given off by fillings, can trigger such symptoms.
A small number of dentists and researchers think they can. Health officials in Sweden recently called for a halt to the use of amalgam, calling it "toxic and unsuitable." But most dental specialists in this country don't think fillings pose any threat to health.
Panel members, for example, noted that people are exposed to more mercury from other sources, including fish, cosmetics and medicine. A tuna fish sandwich, one researcher has estimated, contains at least 25 micrograms of mercury, while someone with amalgam fillings breathes in about 20 micrograms a day.
Dr. McHugh said that studies of dental workers, who risk greater exposure to mercury than their patients, show that they don't suffer higher rates of kidney disease, birth defects or other ailments.
He criticized the "60 Minutes" piece, which showed patients with multiple sclerosis and arthritis claiming that their symptoms eased within weeks of having their amalgam fillings removed.
Removal of amalgam fillings, Dr. McHugh said, has been shown to accelerate the release of mercury for up to two weeks. So those rapid recoveries, he said, could not be linked to reduced mercury.
"These people have tragic, chronic ailments, and they're grasping at straws," he said. "Unfortunately, some people are throwing straws their way."