Proposal Targets Dental Amalgam

A new Clean Water Act proposal would cut discharges of mercury-containing dental amalgam to waterways. Dental amalgam is a mixture of mercury and other metals including silver, copper, and tin that is used to fill cavities. When amalgam fillings are removed in dental offices, the mixture of metals is often rinsed down the drain. Wastewater treatment does not remove the metals, which are discharged to waterways. Under the EPA proposal, dentists would have to install amalgam separators in equipment attached to drainpipes. In addition, dentists would have to report their compliance through annual certification and record keeping. A dozen states already have amalgam separator requirements for dental offices. EPA estimates that adherence to the proposed rule would cut yearly metal discharge to public wastewater treatment plants by at least 8.8 tons, half of which EPA attributes to mercury. The agency is concerned about human exposure to mercury through eating fish that have absorbed toxic methylmercury from aquatic environments.