Dentists Biggest Mercury Polluters, New Study Finds
Health: The metal is widely used in fillings and ends up in the nation's waste water.
By ELIZABETH SHOGREN
TIMES STAFF WRITER
June 6, 2002
WASHINGTON - Coal-fired power plants are notorious for being the biggest source of mercury pollution in the air. But now, new attention is being directed at another, much less known source of mercury contamination in water--dentists.
A new report shows that dentists are the largest single source of mercury pollution in waste water funneled into the nation's treatment plants.
Mercury is a potent toxin that can damage the human brain, spinal cord, kidney and liver, and is especially dangerous for unborn children. While many other sources of mercury pollution have drastically cut their use of the heavy metal, dentists continue to use it widely in fillings.
"Pretty much all the mercury they're using gets released into the environment. Why aren't they doing more to reduce that use?" said Michael Bender, director of the Mercury Policy Project, a foundation-funded group that was one of the authors of the study.
Power plants emit mercury into the air and it falls into streams and rivers. Many dentists flush it down their drains and it goes directly into waste-water treatment plants, which do not effectively filter it from the water.
In a statement responding to the report, the American Dental Assn. said it was aware that some particles from fillings end up in waste water, and it urges dentists to follow proper procedures for handling and recycling the composite used for fillings, which they refer to as "amalgam." But the association argued that the mercury from their fillings remains in a form that is not harmful to humans.
"However, a 1996 study found that when amalgam particles were subjected to simulated waste-water treatment processes, no soluble mercury was detected, even at a concentration of 1 part per billion," according to the statement.
The group stressed that it was currently implementing a new plan to address the problem.
The new report's authors said that dentists, through voluntary or mandatory measures, should trap their waste mercury before it flows into plumbing fixtures that have been contaminated with mercury for years.
The report referred to a 2001 study by the Assn. of Metropolitan Sewerage Agencies that evaluated seven major municipal waste-water treatment plants and determined that dental uses were "by far" the greatest contributors to the mercury reaching their facilities. They were responsible for 40% of the load, three times more than the next largest contributor.
Several other countries regulate releases of dental mercury. In Canada, a new standard requires dentists to trap the pieces of filling before they go down the drain. The goal is to reduce releases by 95% by 2005.
In May, the New Hampshire Legislature became the first in the nation to pass legislation governing disposal methods for dental mercury.
The California Assembly considered a measure to phase out the use of mercury in fillings but did not adopt it.
The report suggests that mercury in dentistry has become the exception while other major users of mercury have changed their practices.
In 1985 dental facilities used 3% of all the mercury used nationwide. Last year, although dentists used less mercury, their use accounted for 20% of all uses. Only two other industries--wiring devices and switches and chloralkali--used more.
Gina Solomon, a physician who focuses on the health effects of mercury for the Natural Resources Defense Council, said that there was still controversy about whether the fillings put dental patients at risk. And she stressed that those who have such fillings should not get them removed, because taking them out heightens the chance of exposure.
However, she said the science is clear that the mercury that goes down the drain can end up in the food chain.
"There is scientific consensus that mercury that ends up in the waste water and water bodies will accumulate in the fish and pose a direct human health problem to people who eat the fish; that is uncontroversial and is something that can be fixed," Solomon said.
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Copyright 2002 Los Angeles Times