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Pennsylvania Dentists Pledge to Purge Mercury from Their Offices

Pennsylvania dentists have partnered with the state Department of Environmental Protection to review voluntary best-management practices for mercury-bearing amalgam wastes and collect obsolete supplies of elemental mercury to prevent the material from entering the environment.

Pennsylvania Environmental Protection Secretary Kathleen A. McGinty signed a Memorandum of Understanding with Pennsylvania Dental Association Chief Executive Officer Camille Kostelac-Cherry to implement a two-pronged approach to reduce mercury discharges from dental offices.

Together, the agencies will collect stored elemental mercury from dental offices statewide for recycling and conduct a review of the voluntary use of best-management practices for reducing amalgam wastes in dental offices. The program is being launched as a three-month trial in 16 eastern Pennsylvania counties before being implemented on a statewide basis.

"This marks a major accomplishment in efforts to ensure a cleaner, healthier environment in Pennsylvania," McGinty said. "I applaud the dentists who have stepped up to work with DEP to tackle this public health and environmental concern. Removing elemental mercury and gathering data on dentists' wastewater management practices will help us improve water quality and ensure public health in Pennsylvania."

In January 2004, DEP kicked off its Mercury Reduction Initiative, a comprehensive strategy to reduce mercury in the environment. Two components of the initiative apply to dental offices: collection of elemental mercury and best management practices for mercury-bearing amalgam wastes.

Dentistry switched from elemental mercury to amalgam capsules about 25 years ago. Previously, dentists mixed the amalgam for fillings using elemental mercury. As a result, many dental offices still have containers of excess elemental mercury stored in their offices. Through surveys conducted in 2001 and 2004, PDA has identified approximately 1,062 pounds of elemental mercury ready for collection from dental offices across the state.

Although use of elemental mercury has become obsolete, mercury compounds still are commonly used in dental practices. Mercury makes up approximately 50% of the amalgam used in dental offices for fillings. Amalgam particles are a potential source of mercury not only in wastewater, but also in groundwater, streams and rivers. Pennsylvania has approximately 8,000 dentists discharging to about 920 publicly owned water treatment works.

Currently, there is little hard data in Pennsylvania to determine the amount of mercury being discharged from dental offices, and the results of national studies are so variable as to be inconclusive. One study found that 60% of mercury in water treatment works comes from dental practices, while a study conducted by the U.S. Navy determined that only 0.006% of mercury leaches out of dental amalgam particulate into the wastewater stream.

While the amount of mercury discharged by dental practices is unknown, the threat of mercury contamination is understood. Methylmercury, a form of mercury that has undergone biological processes, has been well established as a neurotoxin.

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