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Mercury Dental Filling Toxicity

FDA to reexamine use of mercury in dental fillings

Prodded by activists, the agency is reviewing the evidence used to declare that the amount of mercury in dental amalgam is ‘not high enough to cause harm’ to patients.

An advisory panel of outside experts will meet next week to reexamine the basis of the FDA’s conclusions in the latest chapter of a lengthy battle with groups who believe the agency is understating possible links between the mercury in dental amalgam and neurological and other health problems.

The review is “not being taken because of new data,” and “at this time, the FDA is not modifying its existing guidance” that mercury fillings are safe, Nancy Stade, deputy director for policy in the FDA’s Center for Devices and Radiological Health, said in a press briefing Thursday.

But questions about the rigor of the FDA’s science, contained in four petitions to the agency, justify a second look at the evidence, Stade said.

Restrictions on amalgam, which has been used in hundreds of millions of people over the last 150 years, are opposed by the American Dental Assn., which says decisions about use of the substance should remain between patients and their dentists.

The FDA’s current position on mercury fillings followed a lawsuit by anti-amalgam groups that sought to have the substance placed in an FDA classification scheme for medical devices as a first step toward restricting and eventually banning its use.

In settling the suit, the FDA in July 2009 classified amalgam as a moderate-risk item that released levels of mercury “not high enough to cause harm in patients.”

The FDA chose not to require warnings about possible harm to young children and women of childbearing age, said Charles Brown, an attorney for Consumers for Dental Choice, one of the groups that sued the FDA and petitioned the agency to revisit the issue.

Documents released ahead the advisory panel’s meetings next Tuesday and Wednesday indicate that “they’re certainly digging into the science,” Brown said. “But I just don’t know if they can stand up and say to the FDA staff that you’ve been wrong for the last 25 years.”

The advisory committee will not vote on specific recommendations, but will discuss a series of technical questions about how exposure to mercury is measured, whether safe levels of exposure have been set correctly and the reliability of studies of mercury on humans.

The issue is potentially thorny because if the FDA determined that amalgam fillings posed a risk, millions of people would have to decide whether to have them removed, and if so, how to pay for that.

Dental amalgam is a mixture of metals, composed of liquid mercury and a powdered amalgam alloy made up mainly of silver, copper and tin, according to the FDA. Amalgam releases mercury vapor, which can be absorbed by the body. High levels of mercury vapor are associated with brain and kidney disorders.

Advocates of a ban argue that harm from amalgam has been overlooked because mercury builds up in the body over many years, obscuring its link to illness.

Amalgam is silver-colored and the cheapest and longest-lasting dental filling. But its use has been falling in recent years because of the concerns about mercury and a consumer preference for composite resin fillings which can be matched to the color of surrounding teeth.

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