Dental Effluent Guidelines

EPA has promulgated pretreatment standards to reduce discharges of mercury from dental offices into publicly owned treatment works (POTWs).

Dental offices discharge mercury present in amalgam used for fillings. Amalgam separators are a practical, affordable and readily available technology for capturing mercury and other metals before they are discharged into sewers that drain to POTWs. Once captured by a separator, mercury can be recycled.

EPA expects compliance with this final rule will annually reduce the discharge of mercury by 5.1 tons as well as 5.3 tons of other metals found in waste dental amalgam to POTWs.

Mercury is a potent neurotoxin that bioaccumulates in fish and shellfish. Mercury pollution is widespread and a global concern that originates from many diverse sources such as air deposition from municipal and industrial incinerators and combustion of fossil fuels.


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Key facts about dental clinics and mercury:

  • Dental clinics are the main source of mercury discharges to POTWs.
  • EPA estimates about 103,000 dental offices use or remove amalgam in the United States; almost all of these send their wastewater to POTWs.
  • Dentists discharge approximately 5.1 tons of mercury each year to POTWs; most of this mercury is subsequently released to the environment.

Mercury-containing amalgam wastes may find their way into the environment when new fillings are placed or old mercury-containing fillings are drilled out and waste amalgam materials that are flushed into chair-side drains enter the wastewater stream. Mercury entering POTWs frequently partitions into the sludge, the solid material that remains after wastewater is treated. Mercury from waste amalgam therefore can make its way into the environment from the POTW through the incineration, landfilling, or land application of sludge or through surface water discharge


Compliance:

Dental offices that place or remove amalgam must operate and maintain an amalgam separator and must not discharge scrap amalgam or use certain kinds of line cleaners. The effective date of the rule is July 14, 2017. The compliance date for new dental offices ("new sources") is the effective date of the rule. Existing dental offices must comply by July 14, 2020.

  • Existing amalgam separators may be operated for their lifetime or ten years, whichever comes first.
  • When a separator needs replacement, or the ten-year period has ended and the separator does not meet the standard of the final rule, a dental office must replace it with one that meets the requirements of the final rule