Water Quality—Mercury
Dental Mercury
Mercury is used in making dental amalgam, which is a filling material for teeth. Amalgam contains approximately 45-50% mercury, with the remainder consisting of silver, copper, and tin. When dentists remove and place amalgam fillings, small particles of amalgam enter the waste stream and are released to wastewater treatment facilities. Mercury that reaches wastewater treatment facilities is concentrated in the biosolids, which can then be released to the environment when biosolids are incinerated, land-filled, or beneficially re-used.
Amalgam separators can remove most of the amalgam from dental wastewater. In 1999, the International Standardization Organization (ISO) developed a standard for dental amalgam separators (ISO 11143) that included a laboratory test method for determining amalgam removal efficiency of separators and established a minimum amalgam removal efficiency of 95%.
In New England, four states – Connecticut, Maine, New Hampshire, and Vermont – have laws that require installation of amalgam separators. Massachusetts and Rhode Island have voluntary programs. All of the states have developed Best Management Practices for dental offices.