The Subcommittee on Domestic Policy held a hearing entitled “Reducing Dental Mercury Emissions Installing Amalgam Separators and Achieving Compliance.” This hearing will examine existing state and local government initiatives and regulations aimed at reducing dental mercury emissions, evaluate their success, and document the lessons learned. This hearing follows up on concerns raised during the Subcommittee’s first hearing on environmental risks of and regulatory responses to mercury dental fillings, in November 2007.
Elemental mercury and most of its compounds are extremely toxic substances that can causechronic and acute poisoning in human beings who come into contact with them. Mercury iscategorized as an exogenous neurotoxin, because it acts specifically on the brain and nervoussystem when ingested. The health problems that are most commonly associated with mercurypoisoning include oral lesions, birth defects, chronic illnesses, mental disorders, autoimmunedisorders, neurodegenerative diseases, erythrism, and multiple sclerosis. Young children andunborn fetuses are particularly susceptible to mercury poisoning.
Today, in addition to direct air emissions, the improper disposal of mercury-containing wastes byindustries, clinics and others who use it has greatly contributed to dangerously highcontamination levels in many of the country’s water bodies. Once in wastewater, mercury isfurther diffused in the environment in several ways: it enters the atmosphere when mercury-laden biosolids are incinerated; it penetrates the land when it is used as fertilizer or deposited inlandfills, and it pollutes fresh water bodies when inadequately treated wastewater is dischargedinto wastewater treatment plant effluent or when untreated wastewater is discharged fromcombined from sewer outfalls during high flow storm events.The dental industry is by far the largest contributor of mercury found in municipal wastewater.Dental offices nationwide contribute approximately 40 to 50% of mercury in wastewater, nearlythree times as much as the next largest contributor.
A widely used technology that prevents mercury solids, and in some cases dissolved mercury as well, from entering dental wastewater discharge is an amalgam separator unit. An amalgam separator unit is a device that removes 95to 99% of the mercury from dental wastewater primarily through filtration or settling. The separator is typically installed into the dental vacuum pump system where it catches the amalgam particles that are disposed of through the suction drains in dental offices. Localities that haverequired the installation of separators have effectively reduced mercury levels in their municipal wastewaters from 50 to 70%.State and local governments have several options available to them when considering how to ensure that all dental offices – even those that no longer implant new mercury amalgams –effectively limit their mercury releases to wastewater. These include adopting either a voluntary or a mandatory program to install amalgam separators, or creating a permitting program where dental offices are given the choice to test their discharge periodically for mercury or to install anamalgam separator.
The Domestic Policy Subcommittee Majority Staff conducted a national survey of state and localefforts to reduce dental mercury emissions and found that nine states and at least twelve localgovernments have taken action. Based on that sample, Subcommittee Majority Staff has foundthat the mandatory program, or the voluntary program underpinned with the threat of amandatory provision, is the most effective model for achieving the desired reduction in mercury releases.Additionally, our findings reveal several helpful lessons for other state and local governments considering programs to limit dental mercury emissions. They include:
1) The importance of working with local and state dental societies to help educate dentists about the environmental impacts of waste amalgam and to achieve compliance;
2) Authority may already exist for state and local governments considering implementing a mandatory program;
3) Mandating that separators meet the ISO 11143 standard;
4) Potentially incorporating oversight and certification to ensure the efficacy of the separators;
5) Using common clauses and exemptions adopted nationally in statutes, regulations, and ordinances;
6) Establishing appropriate compliance deadlines; and
7) Addressing common concerns about dental mercury emissions reduction programs.
The report below concludes with a list of additional resources.