WHO Calls for 'Phase Down' of Dental Amalgam

October 24, 2011 -- A World Health Organization (WHO) committee this month called for a worldwide reduction in the use of dental amalgam to cut the flow of mercury into the natural environment.

"In an environmental perspective, it is desirable that the use of dental amalgam is reduced," Poul Erik Petersen, DDS, DrOdontSci, responsible officer of the Global Oral Health Programme, told Medscape Medical News.

Dr. Petersen chaired a 2-day conference on amalgam as part of a United Nations effort to organize a worldwide treaty on mercury. The WHO released a report of the proceedings on October 11.

At a meeting in Geneva, Switzerland, from November 16 to 17, 2009, 29 experts from 15 countries concluded that the use of dental amalgam results in 180 to 240 metric tons of mercury being discharged into the atmosphere, soil, and water every year. In contrast, 80 to 100 metric tons are recycled, sequestered, or disposed of securely, the report said. However, the report concludes, amalgam should not be banned outright because alternative filling materials are more expensive and not as reliable.

The report calls for research to improve filling materials and said the use of all dental filling materials should be reduced through measures that prevent caries.

The report drew praise from an antimercury activist group, World Alliance for Mercury-Free Dentistry, which released a statement calling the report a "road map for the end of amalgam."

However, a spokesman for the American Dental Association said it is not necessary to reduce the use of dental amalgam at all. "There is no reason per se to phase down amalgam," Rodway Mackert, DMD, PhD, a professor of dentistry at Georgia Health Sciences University in Augusta, told Medscape Medical News. "The effect of doing that on the amount of mercury going into the environment is negligible."

Dental caries are becoming an increasing problem in middle- and low-income countries as they adopt Western lifestyles, including high consumption of sugars, but have not yet begun widespread preventive programs, such as fluoridation, the report says. As a result, the need for filling materials is expected to grow in these countries.

Already, dental amalgam is releasing "a significant amount" of mercury into the environment, the report found. This pollution results from amalgam made for dental use but diverted to other purposes, from poor disposal practices, and from cremation, the report said.

It laid out "best management practices," including bulk mercury collection, chair-side traps, amalgam separators, vacuum collection, recycling, and commercial waste disposal to prevent mercury from being released into the environment. It cited a US Environmental Protection Agency estimate that 3.7 tons of mercury are discharged into the environment from US dental practices each year.

Dr. Mackert said this is trivial compared with the 1500 tons generated by mining and other industrial uses in the United States, and he cited an US Environmental Protection Agency report saying that human activity only accounts for a third of the total mercury released into the environment. "Most of the mercury in tuna and things like that comes from natural sources like undersea volcanic vents," he said. "Reducing man-generated mercury is so much silliness."

He said the American Dental Association supports best management practices because if mercury gets into sewage sludge, then waste management companies cannot sell the sludge. However, amalgam has clear advantages over other restorative materials, so it should remain available to US dentists, Dr. Mackert said.

The WHO report considered the merits of amalgam vs other restorative materials. It cites a study finding that the repair rate for composite resin restorations was 7 times greater than for amalgams in posterior primary and permanent teeth.

On the hotly contested issue of toxic effects from amalgam, the report quoted a study by the Norwegian Dental Biomaterials Adverse Reaction Unit, finding that "the majority of side-effects of dental filling materials are linked with dental amalgam." Most of these are skin reactions and pain occurring within a week after treatment.

The report noted that amalgam surfaces release mercury vapor into the mouth and lungs, but stopped short of attributing any health effects to this phenomenon, and pointed out that other restorative materials may also cause adverse reactions.

So far, only Norway has completely banned amalgam, but some other Scandinavian countries have policies for reducing its use. The report noted that wealthy countries are better able to avoid amalgam because they have been able to institute caries prevention programs, and because patients can afford more expensive materials.

Less-wealthy countries and indigent people living inside wealthy countries should not be deprived of access to amalgam restorations until better alternatives emerge, the report concludes.

Dr. Mackert has served as an expert witness for dental supply companies sued for producing amalgam. Dr. Petersen has disclosed no relevant financial relationships.