New Regulations for Mercury and Metallic Discharges from Dental Amalgam Services - Articles

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Posted by: Jarod Word on Mar 15, 2018
When dentists remove old amalgam fillings from cavities or place a new filling, mercury from the amalgam enters the wastewater of the dental office. These dental office wastewater discharges are the main source of mercury into wastewater treatment facilities and subsequent release to the environment. Mercury is a potent neurotoxin that can have a wide range of health effects, and mercury pollution is a global concern. Mercury tends to bioaccumulate in fish and shellfish, meaning it concentrates in tissue and thus can move up the food chain, posing a risk to humans and other higher vertebrates.  Eating such fish and shellfish is the main source of human exposure to methylmercury (a highly toxic form of mercury) in the United States.
The Environmental Protection Agency (EPA) has promulgated new wastewater effluent standards to reduce the discharge of mercury and other metals from dental offices. These “pretreatment” standards were codified in 40 CFR Part 411, with the Final Rule effective as of July 14, 2017. Existing dental dischargers have until July 14, 2020, to come into compliance with the regulations; new discharges immediately after the effective date must be in compliance. EPA expects compliance with the rule to reduce the discharge of metals by at least 10.2 tons per year, about half of which is mercury.
The regulations apply to offices, including institutions such as dental schools and clinics, where dentistry is practiced and that discharge to a wastewater treatment facility. It does not apply to mobile units, non-discharge offices or to a list of specific dental specialties that do not perform filling operations.  Applicable offices are required to either end their discharge or to operate and maintain an amalgam separator or equivalent technology for removal of mercury and metals from their discharges. The separators are expected to impose a cost of about $800 annually per office, and the EPA projects the annual cost of the rule nationally will be $59 million to $61 million. The separated mercury is available for recycling.
Like other wastewater pretreatment standards, compliance with this rule is administered by the local “Control Authority,” typically the local or state wastewater agency. Under the rule, the City of Memphis’s Industrial Monitoring & Pretreatment Program is responsible for the evaluation and administration of approximately 600 dentists at more than 300 offices, including in Germantown and Bartlett. In addition to the installation of amalgam separators, regulated offices are also required to implement a set of best management practices to ensure compliance and to meet certain reporting requirements.
In order to reduce the burden of compliance and reporting on both the offices and Control Authorities, the final rule establishes that dental dischargers are not Significant Industrial Users, as defined in 40 CFR 403, and are not Categorical Industrial Users or “industrial users subject to categorical pretreatment standards,” unless designated such by the Control Authority. The rule does not require Control Authorities to implement the traditional suite of oversight requirements in the General Pretreatment Regulations that become applicable upon the promulgation of categorical pretreatment standards for an industrial category. For reporting, the regulation was designed to require submittal of a simple one-time compliance report. This regulatory approach also eliminates the additional oversight requirements for Control Authorities that are typically associated with SIUs, such as permitting and annual inspections of individual dental offices, although the Control Authority retains the right to inspect, evaluate and permit facilities as it judges necessary.
Offices choosing to capture mercury waste should be aware that they may now be generating a hazardous waste under the Resource Conservation and Recovery Act (RCRA), depending on the volumes captured and how the materials are recycled or otherwise disposed of, and may be subject to RCRA’s hazardous waste regulations and reporting. The EPA generally does not expect dental offices collecting amalgam waste to be above the “Very Small Quantity Generators” threshold. VSQGs are exempt from most RCRA requirements.   

— Ben Day is a senior environmental specialist with Tioga Environmental Consultants in Memphis. He can be contacted at and (901) 791-2432.