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Advocacy Alert 14-21


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To: Members & Affiliates
From: National Office
Date: October 22, 2014
Reference: AA 14-21


EPA’s proposed Dental Amalgam Separator rule pdf button, published in the October 22 Federal Register, would establish pretreatment standards for the over 100,000 dental offices that place or removal amalgam fillings, substantially affecting publicly owned treatment works (POTWs) with pretreatment programs. The proposal requires all dental offices to install and maintain dental amalgam separators that achieve a 99 percent reduction of total mercury, follow best management practices (BMPs), and submit annual certification reports to their POTW or other pretreatment control authority.

Since the number of dental offices subject to national pretreatment standards is about ten times the number of Categorical Industrial Users that currently have pretreatment standards, EPA proposes changing the General Pretreatment Regulations to establish a Dental Industrial User (DIU) category. This DIU category would result in less oversight responsibility for POTWs, as long as the dental office remains in compliance with all requirements.

This Advocacy Alert provides a summary of the requirements proposed by EPA for dental offices and POTWs, as well as the financial and environmental impacts of the proposal. Comments on the proposal are due by December 22, but NACWA and the American Dental Association (ADA) will be jointly requesting an extension of the comment deadline. NACWA plans to provide extensive comments to EPA on this proposal and will be working with its Pretreatment and Pollution Prevention Committee to review the rule and determine what information is needed from NACWA members. Please contact This e-mail address is being protected from spambots. You need JavaScript enabled to view it with any input on the proposed rule.


Dental amalgam is approximately 50% mercury, 35% silver, 9% tin, and 6% copper, with small amounts of zinc, indium, and palladium. Amalgam is discharged at dental offices during the placement of a filling, when excess amalgam is used so that it can be carved out to the shape of the tooth. Amalgam is also discharged when fillings are removed or replaced. Use of dental amalgam for fillings has been decreasing from 157 million restorations in 1979 to 52.5 million restorations in 2005, and over half of dentists no longer use dental amalgam for fillings. EPA estimates that 4.4 tons of mercury is currently discharged to POTWs from dental offices each year. Twelve states and at least 19 localities have already established mandatory dental amalgam separator programs, requiring dentists to install separators and follow BMPs, and other localities have voluntary programs.

EPA first began considering pretreatment standards for dental amalgam in its Preliminary 2006 Effluent Guidelines (ELG) Plan when it identified the Health Services Industry for a detailed study, with a focus on dental amalgam and unused pharmaceutical disposal. In the Final 2008 ELG Plan, EPA did not identify dental facilities for ELG rulemaking, stating that the Agency would “continue to examine the percentage of dentists using amalgam separators and their effectiveness at recovering dental amalgam.” EPA, NACWA, and ADA signed a Memorandum of Understanding (MOU) in 2008 to encourage the voluntary use of dental amalgam separators and establish methods of tracking their use.

EPA changed course on dental amalgam separators with its 2010 ELG Plan. The Preliminary 2010 Plan, published in December 2009, reaffirmed EPA’s decision not to pursue a rulemaking for dental amalgam. However, the Final 2010 Plan, published in October 2011, stated that “given the human health and aquatic-life impacts associated with mercury, the level of stakeholder interest, and the availability of a technological solution, EPA decided to initiate rulemaking to develop pretreatment standards for dental mercury to more thoroughly and expeditiously address this water pollution problem.” The Final 2010 Plan announced a schedule of October 2011 for the proposed rule and October 2012 for the final rule. EPA communicated in 2012 to NACWA and other stakeholders that the rule had been drafted, but that it had raised some concerns during informal interagency review with the White House’s Office of Management and Budget (OMB). The Preliminary 2012 ELG plan listed the schedule for publication of the rule as “to be determined.”

NACWA has repeatedly stated to EPA that a national dental amalgam rule is not necessary, since successful state and local amalgam separator programs have been established where they are needed, while utilities without mercury issues can better use their resources on other environmental problems. NACWA met with EPA on several occasions to discuss the difficulties associated with establishing pretreatment standards for over 100,00 dental offices, and in commentspdf button on the Preliminary 2012 ELG Plan, NACWA asked that EPA either drop the rule from consideration or formally propose it. EPA formally submitted the rule to the White House Office of Management and Budget (OMB) in May 2014, and NACWA met with OMB in August 2014 to explain its concerns with an amalgam separator rule.

Proposed Rule

EPA proposed a pretreatment standard that requires dental offices to install dental amalgam separators, follow BMPs, and certify that they have met all requirements. POTWs and other pretreatment control authorities must provide oversight of the dental offices. EPA proposes revisions to the General Pretreatment Regulations to reduce these oversight requirements, as long as dental offices remain in compliance. EPA proposes a compliance date of three years after the effective date of the final rule, the maximum length of time allowed by the Clean Water Act.

Pretreatment Standards for Dental Offices

The proposed pretreatment standard would establish the following requirements for dental offices:

    • At least 99.0% of total mercury must be removed from amalgam process wastewater, based on the best available technology. This requirement may be met by installation and operation of at least one dental amalgam separator certified to achieve a 99% reduction of total mercury according to the 2008 ISO 11143 standard.
    • Two BMPs must be used by dental offices:
      • Scrap amalgam (including from chair-side traps, screens, vacuum pump filters, and dental tools) must not be flushed down the drain; and
      • Chair side traps must be cleaned at least weekly with non-bleach, non-chlorine cleaners that have a pH between 6 and 8.
    • Dental offices must prepare a one-time baseline report and initial compliance report, and then provide an annual certification statement to the proper Control Authority (see below for more information on Control Authorities).
    • Dental offices that have already installed dental amalgam separators may continue using their existing separators, if they comply with the BMPs and recordkeeping requirements, until ten years from the effective date of the final rule unless the separator needs to be replaced before then.
    • Dental offices that do not apply or remove dental amalgam are required to report baseline information and certify that they do not and will not install or remove amalgam. These offices do not need to install dental amalgam separators or follow BMPs.

Responsibilities of Control Authorities

The Control Authority is the POTW if the POTW has an approved Pretreatment Program. Approximately 1,500 POTWs have approved pretreatment programs, while 13,500 small POTWs do not. If the POTW does not have a Pretreatment Program, then the Control Authority is the state if the state has an approved state Pretreatment Program, or the EPA region for that state if the state does not have an approved state Pretreatment Program. An approved state Pretreatment Program or EPA region may assume local responsibilities for POTWs that have dental offices but no pretreatment program. EPA “anticipates” that the states will do this rather than require a POTW to develop a full pretreatment program solely to regulate dental offices, but there is no requirement that states or EPA regions assume this responsibility.

Under current regulations, the Control Authority must provide oversight of all categorical industrial users (CIUs), and for CIUs classified as significant industrial users (SIUs), this oversight includes conducting annual inspections and sampling of effluent, as well as issuing a permit or other control mechanism. Given the over 100,000 dental offices that would require oversight by Control Authorities – ten times more than the current number of CIUs – EPA proposes to revise the General Pretreatment Regulations to establish a new classification of CIU. Dental offices would be classified as “Dental Industrial Users” (DIUs), which would not be subject to the oversight requirements for SIUs.

DIUs must maintain compliance to keep their DIU status, otherwise Control Authorities must treat the dental office as an SIU. A DIU would be in significant noncompliance if it was 45 days late with its annual certification, which would trigger a Control Authority enforcement initiative. If compliance was achieved within 90 days, which would include an inspection and verification by the Control Authority, then the dental office would remain a DIU. If compliance was not achieved within 90 days, the Control Authority would be required to provide full oversight of the dental office as an SIU. The proposal does not explain if or when a dental office that became classified as an SIU could again become a DIU.

Environmental and Financial Impacts of Proposed Rule

EPA estimates that the average annual cost to a dental office for a dental amalgam separator is $700. EPA estimates that Control Authorities as a whole would spend an average of 17,400 hours and $960,000 each year to review the information submitted by dentists to certify that they meet the requirements of the proposed rule. The proposal states that “EPA estimates the annual cost of the proposed rule would be $44 to $49 million.”

EPA makes several assumptions and estimates to determine the reduction of mercury discharges that would be achieved by the proposal:

    • The 12 states that require amalgam separators are assumed to have 100% compliance. For states without mandatory programs, EPA assumes that 20% of dentists have voluntarily installed amalgam separators. This results in approximately 65,000 dental offices currently without separators and 44,000 offices with separators already installed.
    • EPA assumes that all dental offices have chair side traps or a combination of chair side traps and vacuum filters that result in 68% and 78% collection of dental amalgam, respectively.
    • EPA estimates that 4.4 tons of mercury are discharged to POTWs annually from dental offices from placement and removal of fillings.
    • EPA estimates that POTWs remove 90% of total mercury from wastewater, based on the 1982 50 POTW Study.

With these assumptions, EPA calculates that 880 lbs of mercury from dental amalgam are discharged into surface waters by POTWs annually, and this would be reduced to 14 lbs of mercury annually with nationwide dental amalgam separator use. According to EPA, this results in discharges of mercury to waters of the U.S. being reduced by 860 lbs per year as a result of the proposed rule.

NACWA is still reviewing the Technical and Economic Development Documentpdf button for the proposal to determine how EPA calculated these financial and environmental impacts. However, using EPA’s stated minimum cost of $44 million annual cost of the proposed rule to reduce mercury discharges by 860 lbs results in an annual cost of over $50,000 per pound of mercury removed. NACWA believes that this calculated cost per pound may be too low for several reasons. First, EPA’s estimate of $960,000 for Control Authorities to review the certification information submitted by dental offices is likely too low, and costs to POTWs to identify and communicate with dental offices, especially when the rule first goes into effect, will likely be much higher. Second, the 90% removal efficiency of mercury by POTWs from the outdated 1982 50 POTW Study is likely much too low. Finally, EPA may have overestimated the number of fillings placed each year by using information from 2005, since dentists continue to move away from using dental amalgam.

NACWA Response to Proposal

NACWA and ADA will be jointly submitting a request for an extension of the comment period of the rule, given the tremendous potential impact of this proposed rule on dental offices and POTWs and the need to collect information to fully evaluate the impact of the rule. NA CWA is also discussing these issues with organizations representing the states as well as with ADA to get their input on the proposal.

NACWA’s Pretreatment and Pollution Prevention Committee will be holding a conference call on November 6, 2:00 pm Eastern, to discuss the proposal. Further information about this call will be sent to the Committee and announced in the October 31 Clean Water Current. NACWA will be requesting data and information from member agencies soon. Initial comments and any relevant information may be sent to Cynthia Finley at This e-mail address is being protected from spambots. You need JavaScript enabled to view it .



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