Mercury in Dental Amalgam
- Best management practices for environmentally responsible dentistry
- Environmentally Responsible Dentistry Teaching Module
- Dental Amalgam Waste Collections and Recycling Campaign for Dentists
Information about Dental Amalgam from Other U.S. Government Agencies
Using Dental Amalgam
- What is dental amalgam?
- Are dental amalgam fillings safe?
- Are there alternatives to using dental amalgam fillings?
- How much mercury is used in dental amalgam?
Mercury Pollution from Amalgam Waste
- How does amalgam waste affect the environment?
- How much mercury contamination in wastewater comes from dental sources?
What Dentists Can Do To Prevent Mercury Pollution
EPA, State, Tribal, and Community Actions
Using Dental Amalgam
What is Dental Amalgam?
Dental amalgam, sometimes referred to as “silver filling,” is a silver-colored material used to fill (restore) teeth that have cavities. Dental amalgam is made of two nearly equal parts: liquid mercury and a powder containing silver, tin, copper, zinc and other metals. Amalgam is one of the most commonly used tooth fillings, and is considered to be a safe, sound, and effective treatment for tooth decay.
Are Dental Amalgam Fillings Safe?
When amalgam fillings are placed in or removed from teeth, they can release a small amount of mercury vapor. Amalgam can also release small amounts of mercury vapor during chewing, and people can absorb these vapors by inhaling or ingesting them. High levels of mercury vapor exposure are associated with adverse effects in the brain and the kidneys.
Since the 1990s, several federal agencies have reviewed the scientific literature looking for links between dental amalgam and health problems. According to the Centers for Disease Control and Prevention (CDC), there is little scientific evidence that the health of the vast majority of people with dental amalgam is compromised, nor that removing amalgam fillings has any beneficial effect on health.
A 2004 review of the scientific literature conducted for the U.S. Public Health Service found “insufficient evidence of a link between dental mercury and health problems, except in rare instances of allergic reaction.” View a CDC factsheet that presents more information on dental amalgam use, benefits and health issues.
FDA Classification of Dental Amalgam as a Medical Device
Dental amalgam is considered to be a medical device, and is regulated by the Food and Drug Administration (FDA). FDA is responsible for ensuring that dental amalgam is reasonably safe and effective, and that, among other things, the product labeling seen by dentists has adequate directions for use and includes any appropriate warnings.
In 2008, FDA reviewed the best available scientific evidence to determine whether the low levels of mercury vapor associated with dental amalgam fillings are a cause for concern. Based on this evidence, FDA considers dental amalgam fillings safe for adults and children ages six and above. FDA recommends that patients in specific populations who might be more vulnerable to mercury (pregnant women and their fetuses, and children under the age of six, including those who are breastfed), speak with their dentists about any concerns they have about the potential effects of using dental amalgam.Learn more about the potential benefits and risks of dental amalgam at US FDA's website.
Are There Alternatives to Using Dental Amalgam Fillings?
Presently, there are five other types of restorative materials for tooth decay:
- resin composite,
- glass ionomer,
- resin ionomer,
- porcelain, and
- gold alloys.
The choice of dental treatment rests with dental professionals and their patients, so talk with your dentist about available dental treatment options. The American Dental Association provides a brochure for dental patients (PDF) (6 pp, 133K, about PDF) on the advantages and disadvantages of various types of dental fillings.
How Much Mercury Is Used in Dental Amalgam?
The Interstate Mercury Education and Reduction Clearinghouse (IMERC), managed by the Northeast Waste Management Officials’ Association, reports that the total mercury sold in dental amalgam in 2004 was 30.4 tons (26% of mercury in all products). This total is based on data submitted to IMERC by five dental amalgam manufacturers who represent the entire U.S. market for dental amalgam capsules. More detailed information can be found in the online IMERC fact sheet, Mercury Use in Dental Amalgam, and its 2008 report, Trends in Mercury Use in Products (PDF) (30 pp., 2.8 MB, about PDF)
The amount of mercury used in consumer products dropped 83% between 1980 and 1997, largely as a result of federal legislation and state regulatory limits on mercury usage in batteries and EPA’s regulatory ban on mercury in paint.
Amalgam use in the U.S. is slowly declining because the incidence of dental decay is decreasing and because improved substitute materials are now available for certain applications. The decreasing cost of non-mercury substitutes has also contributed to a decline in consumer demand for amalgam.
Mercury Pollution from Amalgam Waste
How Does Amalgam Waste Affect The Environment?
If improperly managed by dental offices, dental amalgam waste can be released into the environment. Dentists should use dental amalgam separators to catch and hold the excess amalgam waste coming from office spittoons. Without dental amalgam separators, the excess amalgam waste will be released to the sewers via drains in the dental offices. While Publicly-Owned Treatment Works (POTWs) have around a 90% efficiency rate of removing amalgam from wastewaters, a small amount of waste amalgam is discharged from POTWs into surface waters around the plants.
At the treatment plant, the amalgam waste settles out as a component of sewage sludge that is then disposed:
- in landfills,
- through incineration, or
- by applying the sludge to agricultural land as fertilizer.
If the amalgam waste is sent to a landfill, the mercury may be released into the groundwater or air. If the mercury is incinerated, mercury may be emitted to the air from the incinerator stacks. And finally, if mercury-contaminated sludge is used as an agricultural fertilizer, some of the mercury used as fertilizer may also evaporate to the atmosphere. Through precipitation, this airborne mercury eventually gets deposited onto water bodies, land and vegetation. Some dentists throw their excess amalgam into special medical waste (“red bag”) containers, believing this to be an environmentally safe disposal practice. If waste amalgam solids are improperly disposed in medical red bags, however, the amalgam waste may be incinerated and mercury may be emitted to the air from the incinerator stacks. This airborne mercury is eventually deposited into water bodies and onto land.
Mercury amalgam also accumulates on dental supplies, such as cotton swabs and gauze, and these materials are usually deposited in the regular trash. In local areas where trash is incinerated, the mercury in this trash can be released via air emissions.
How Much Mercury Contamination in Wastewater Comes From Dental Sources?
Mercury from dental offices contributes significantly to the overall mercury contamination in wastewater. In an August 2008 report (PDF) (76 pp., 1.0 MB, about PDF) on the dental industry, EPA estimated that in 2008 there were approximately 122,000 dental offices (approximately 160,000 dentists) that used or removed dental amalgam in the U.S., and that those offices discharged approximately 3.7 tons of mercury each year to POTWs. Dental offices were found in 2003 to have been the source of 50 percent of all mercury pollution entering POTWs.
A 2002 study by the New York Academy of Sciences, Pollution Prevention and Management Strategies for Mercury in the New York/New Jersey Harbor (PDF) (116 pp., 799K, about PDF) , indicated that as much as 40 percent of total mercury loadings in the New York/New Jersey harbor and watershed may have come from dental offices. In another study in 2002, Mercury Source Control & Pollution Prevention Program Evaluation (PDF) (62 pp., 240K, about PDF), the National Association of Clean Water Agencies (NACWA) estimated that nearly 40 percent of the mercury in the nation’s wastewater system came from dental offices, and that mercury discharged from dental offices far exceeded all other commercial and residential sources, each of which was below ten percent.
EPA, State, Tribal and Community Actions
Effluent Guideline Rulemaking
EPA regulates the discharge of pollutants to wastewater by establishing national regulations known as "effluent guidelines" and "pretreatment standards." These regulations reduce pollutant discharges from specific industries that discharge either directly to surface waters or indirectly through POTWs. EPA announced in September 2010 the start of regulatory development (called an effluent guideline rulemaking) to reduce discharges of mercury from dental offices.
The new regulation will establish requirements for the discharge of dental amalgam and mercury, based on the application of the best technology capable of removing the amalgam. EPA intends to focus its technology assessment on amalgam separators.
Dental amalgam waste settles out as a component of sewage sludge at wastewater treatment plants. In February 2011, EPA issued a new rule that limits air emissions for mercury and eight other hazardous air pollutants from publicly owned incinerators that burn sewage sludge. This rule, published in the Federal Register on March 21, 2011 (PDF) (83pp., 579K, about PDF) , is a major step toward keeping mercury releases from dental amalgam waste out of the environment. Learn more about the rule at EPA's Emission Standards for Boilers and Process Heaters and Commercial/Industrial Soild Waste Incinerators site.
The Environmentally Responsible Dentist – Dental Amalgam Recycling: Principles, Pathways and Practice (NOTE: registration required to view document) - EPA and Marquette University's School of Dentistry developed a teaching module to educate dental students on proper amalgam waste management. The module aims to raise dental students' awareness of the dental amalgam waste issue and to provide the students with practical steps to reduce the release of amalgam waste to the environment. The module highlights four actions to properly manage amalgam waste. These actions are abbreviated as GRIT: "Gray Bag It," "Recycle It," "Install It," and "Teach It." The GRIT steps highlight ADA's best management practices for amalgam waste and encourage dental students to practice environmentally responsible dentistry.
EPA has worked with dental amalgam manufacturers to encourage proper dental amalgam waste management as a public education effort under section 8001 of the Solid Waste Disposal Act. The Agency developed inserts to be included in dental amalgam packages for distribution to dentists. The insert encourages dentists to collect mercury amalgam waste using gray bags and amalgam separators, and to send the waste for recycling at a RCRA-permitted mercury retorter or recycler.
Dental amalgam waste is a significant contributor of mercury discharges to municipal wastewater treatment facilities, often referred to as “publicly-owned treatment works” (POTWs). While POTWs have a high efficiency rate of removing amalgam from wastewaters (around 90%), a small amount of waste amalgam is discharged from POTWs into surface waters around the plants. Approximately 50% of mercury entering POTWs comes from dental amalgam waste. Dental offices discharge approximately 3.7 tons of mercury each year to POTWs.
EPA highly encourages dental amalgam manufacturers to use an EPA-provided insert in their dental amalgam packaging. The insert can be pressed into the lid, placed in the packaging, or adhered as a sticker.
Dental amalgam manufacturers should keep these conditions in mind if they choose to use these inserts in their dental amalgam products:
EPA cannot and does not endorse any particular product or service.
Companies cannot use the EPA seal, identifier or logo for their own promotional purposes.
The insert templates cannot be altered in any way, such as adding a company logo.
Many state and tribal environmental agencies require local wastewater treatment facilities to meet very low mercury effluent limits in response to three key factors:
- EPA's water quality criterion for human health of 0.3 milligrams of methylmercury per kilogram of fish tissue. The criterion is the maximum advisable concentration of methylmercury in freshwater and estuarine fish and shellfish tissue that is protective of consumers of fish and shellfish.
- The increasing number of mercury-related fish consumption advisories being issued across the country.
- The availability of more sensitive analytical techniques that allow wastewater treatment agencies and regulatory agencies to better measure discharges of mercury from POTWs.
Some state and local governments have implemented mandatory and voluntary programs to reduce dental mercury discharges. More information can be found in EPA’s Health Services Industry Detailed Study: Dental Amalgam (August 2008) (PDF) (76 pp, 1.0 MB, about PDF). The National Conference of State Legislatures lists state legislature internet links , including links to information on state laws requiring dentists to install amalgam separators.
Increasing numbers of local POTW pretreatment programs are beginning to require dental offices to reduce their discharges of mercury. The NACWA has published information for local wastewater treatment agencies on the issue of mercury contamination of wastewater. In 2006, NACWA published a paper titled Controlling Mercury in Wastewater Discharges from Dental Clinics (PDF) (January 2006) (14 pp, 232K, about PDF) to help POTWs and other organizations understand some of the technical issues associated with the generation of dental clinic wastewater, and to provides introductory information for those communities considering formal programs requiring the installation of amalgam separators.
The Quicksilver Caucus (QSC), a coalition of state government associations, has published its “Dental Mercury Amalgam Waste Management White Paper” (PDF) (April 2008) (24 pp, 100K, about PDF to help states determine how to reduce sources of dental mercury amalgam released to the environment from the dental sector. The paper provides information on successful state and local amalgam separator requirements, amalgam alternatives, and innovative approaches to reducing mercury amalgam releases. The QSC has also published Case Studies of Five Dental Mercury Amalgam Separator Programs (PDF) (May 2008) (20 pp, 87K, about PDF).
What Dentists Can Do to Prevent Mercury Pollution
How Can Dentists Capture and Recycle Dental Amalgam Waste?
Some states have mandatory dental amalgam program requirements, including installation of amalgam separators. Specifics on state requirements can be found at EPA's August 2008 Health Services Industry Detailed Study: Dental Amalgam (PDF) (76 pp, 1 MB, about PDF) Additionally, the National Conference of State Legislatures lists state legislature internet links, including links to information on state laws requiring dentists to install amalgam separators
Best Management Practices
Most dental offices currently use some type of basic filtration system to reduce the amount of mercury solids passing into the sewer system. The installation of amalgam separators, which generally have a removal efficiency of 95%, can further reduce discharges to wastewater. In October 2007, the American Dental Association (ADA) adopted its new Best Management Practices for Amalgam Waste (PDF) (8 pp, 118K, about PDF) , which recommends two very important and effective “best practices”:
- the use of dental amalgam separators, and
- the recycling or retorting of captured amalgam solid waste.
The G.R.I.T. actions below highlight the American Dental Association’s (ADA’s) best management practices for amalgam waste. EPA encourages both dentists and dental students to employ the GRIT actions in their practices to prevent mercury pollution.
“G”: Gray Bag It – Discard amalgam wastes into a gray bag.
"R": Recycle It – Select a responsible dental amalgam recycler who can manage your waste amalgam safely from the list of recyclers below.
“I”: Install It — Install an amalgam separator to capture up to 95% of the mercury going down the drain. This is the KEY to success.
“T”: Teach It – Educate and train staff about the proper management of dental amalgam.
See the box below for a list of these facilities; the American Dental Association also has a directory of dental waste recyclers (PDF).
Facilities Permitted under the Resource Conservation and Recovery Act (RCRA) to Accept Dental Amalgam Waste
Drawing upon information received from recovery facilities related to their 2007 RCRA Biennial Report forms, EPA has compiled the following list of RCRA-permitted mercury retorters that accept dental amalgam waste.
PLEASE NOTE: This list is based upon information submitted directly by the facilities and is for informational purposes only. The list may not be comprehensive or up-to-date. For additional information, please contact your state hazardous waste authority. Inclusion on the list does not confer any rights or benefits, nor does it imply any governmental sanction or endorsement whatsoever by the U.S. EPA or the federal government.
Bethlehem Apparatus Company, Inc.
890 Front Street
Hellertown, PA 18055
Mercury Waste Solutions, Inc.
21211 Durand Avenue
Union Grove, WI 53182
Advanced Environmental Recycling Company, LLC (Corporate
2591 Mitchell Avenue
Allentown, PA 18103
Veolia ES Technical Solutions, LLC (Corporate Office)
700 East Butterfield Road
Lombard, IL 60148