EPA recently finalized technology-based pretreatment standards under the Clean Water Act to reduce discharges of mercury and other metals from dental offices into municipal wastewater treatment plants, also known as publicly owned treatment works (POTWs). The United States Environmental Protection Agency (U.S. EPA) determined that dental practices discharge over five tons of mercury every year into POTWs. Mercury-containing amalgam wastes enter the environment when new fillings are placed, old mercury-containing fillings are drilled out, or when waste amalgam materials are flushed into chair-side drains that are connected to the wastewater stream. When mercury enters a POTW, it can partition into the sludge, which is ultimately incinerated, landfilled, applied to the land, or discharged to surface waters. EPA estimates over 100,000 dental offices use or remove amalgam in the United States and almost all of these practices discharge their wastewater to POTWs.
The Final Rule, published in the Federal Register on June 14, 2017 and effective on July 14, 2017, requires all dental practices, dental schools, and dental clinics that discharge wastewater to a POTW, and that regularly place or remove amalgam, to install an approved amalgam separator or other approved removal device no later than July 14, 2020. An amalgam separator is a device designed to remove solids, including mercury and other metals, from dental office wastewater. Once captured by the separator, these metals can be recycled.
Under the Final Rule, newly established practices will be required to install ISO 11143 compliant amalgam separators or other removal devices prior to July 14, 2020. Currently operating practices with existing amalgam separators can continue to operate that separator for its lifetime or for 10 years, whichever comes first. When the separator requires replacement or the 10-year period has ended, existing practices will need to replace the amalgam separator with one that is ISO 11143 compliant. In addition, the Final Rule prohibits the discharge of waste (scrap) amalgam into the wastewater stream and prohibits the use of line cleaners that are oxidizing or acidic and that have a pH higher than 8 or lower than 6 such as bleach, chlorine, iodine, and peroxide. All affected practices are also subject to amalgam separator inspection and one-time reporting requirements.
The Final Rule does not apply to mobile units or offices where the practice of dentistry consists only of oral pathology, oral and maxillofacial radiology, oral and maxillofacial surgery, orthodontics, periodontics, or prosthodontics. These specialty practices are not expected to engage in the practice of amalgam restorations or removals, and are thus not expected to have any wastewater discharges containing dental amalgam. In addition, dental dischargers that do not place dental amalgam, and do not remove dental amalgam except in limited emergency or unplanned, unanticipated circumstances, are exempt from any further requirements as long as they certify such in their One-Time Compliance Report.