EPA’s Dental Amalgam Separator Rule: It’s Not Filling a Hole


Keeping mercury out of the environment is definitely a good thing, since it is a persistent, bioaccumulative, and toxic pollutant.  Clean water agencies have long worked to reduce their mercury discharges into the environment, and a variety of pollution prevention measures have resulted in the reduction of mercury discharges from wastewater treatment facilities.

Last year, EPA proposed a rule that would require dental amalgam separators in all dental offices that place or remove amalgam fillings, which are about half mercury.  The amalgam separators remove the amalgam particles from water before it is discharged into a sewer system, and it would be great if all dentists would install and properly maintain separators in their offices.  However, EPA’s rule would require amalgam separator installation by making it a pretreatment standard that wastewater utilities would be responsible for enforcing.  Since there are over 100,000 dental offices in the U.S., this pretreatment standard would create a huge burden for local utilities. 

Twelve states and many localities already have laws or regulations that require dental offices to install separators, and some dental offices outside of these jurisdictions have also installed separators voluntarily.  Clean water agencies have the ability, through their pretreatment programs, to set local requirements to reduce pollutant discharges to their treatment plants, and they can start their own programs to require separators if needed.  EPA estimates that 40% of dentists that place or remove amalgam have already installed separators, either voluntarily or because of state or local programs. 

In 2008, EPA, NACWA, and the American Dental Association (ADA) signed a Memorandum of Understanding (MOU) to promote additional voluntary use of separators.  However, EPA announced in 2010 that it would propose a dental amalgam separator rule, without giving the MOU a chance to work. 

There are many problems with EPA’s proposed rule, and many of these problems are described in the comments that NACWA submitted to the Agency last week.  Overall, EPA overestimated the amount of mercury that the rule would prevent from being discharged into water and greatly underestimated the cost of the rule to utilities.  EPA estimated an annual cost of only $960,000 for Control Authorities (clean water agencies and states) to implement the rule – with less than 10 minutes required to ensure compliance from each dental office.  From the experience of utilities that already have rules, this time will be much greater, averaging two hours per dental office each year.  NACWA’s annual cost estimate for Control Authorities is $12 million, plus an initial cost of $24 million for Control Authorities to develop their dental amalgam separator programs (identifying dental offices in their service areas, communicating requirements, collecting baseline reports, etc.).

EPA’s estimates result in a cost of about $55,000 per pound of mercury removed each year.  NACWA’s estimate is at least $154,000 per pound of mercury removed each year, plus the initial program development cost of $24 million.  The cost per pound of mercury is probably even greater than these estimates, because EPA uses the number of fillings placed and removed in 2005 to calculate the amount of mercury removed, and the use of dental amalgam fillings has been consistently decreasing. 

In addition to these high costs, data from utilities show that this rule is simply not needed from an environmental perspective.  NACWA conducted a survey of over 200 wastewater treatment plants, and the data submitted for the survey shows that utilities have very low concentrations of mercury in their effluent and biosolids.  Utilities are meeting all of their regulatory requirements for their discharge permits and for the use of their biosolids.  Utilities without mercury problems should be allowed to prioritize their resources for their most important environmental issues and should not be forced to establish unneeded dental amalgam separator programs. 

While requiring dental offices to use dental amalgam separators sounds like a good idea, EPA’s proposed rule is not the best way to accomplish this.  The amount of mercury discharged into the environment by utilities is tiny compared to other sources, with dental amalgam contributing only about 1 percent or less of the mercury in the environment.  If there is a demonstrated water quality need to reduce mercury dischargers, or a reason for biosolids mercury contents to be reduced, utilities should be allowed to determine the best methods for accomplishing this.  In many locations, this has resulted in the establishment of successful voluntary or mandatory dental amalgam separator programs.  EPA should withdraw this unnecessary rule, allow the ADA and utilities to increase voluntary installation of separators, and allow utilities to establish mandatory programs only if they are needed. 

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