The Environmental Protection Agency wants to reduce the amount of mercury from dentistry that gets into waterways.
The agency said Thursday that dental offices are responsible for about half of the mercury that gets into public water treatment facilities.
The metal comes from alloys used for dental fillings and can be toxic to fish and humans.
“This is a common sense rule that calls for capturing mercury at a relatively low cost before it is dispersed into the [water treatment facilities],” Kenneth Kopocis, the EPA’s deputy assistant administrator for water, said in a statement.
“The rule would strengthen human health protection by requiring removals based on the use of a technology and practices that approximately 40 percent of dentists across the country already employ,” he said, crediting the American Dental Association, and state and local authorities with deployment of mercury removal technology.
Under the proposed rule, certain dental offices would be required to use equipment known as amalgam separators to remove mercury from wastewater, or use other technology that achieves a similar result.
In addition to the benefits to fish and humans, the EPA said the rule would help the U.S. to meet its responsibilities under the Minamata Convention on Mercury, drafted last year to reduce mercury internationally in the environment.
The rule would cut at least 8.8 tons of metal discharged into public water treatment facilities each year, the EPA estimated.