Dental Amalgam Recycling

Pathways, Principles, & Practice

The Marquette University School of Dentistry

The Environmental Protection Agency

Marquette University School of Dentistry Dental Amalgam Recycling
WELCOME!

Gary L. Stafford DMD

Assistant Professor

Program Director for General Dentistry

Marquette University School of Dentistry

Marquette University School of Dentistry Dental Amalgam Recycling
WELCOME!

David J. Carver

Chemical Engineer

Office of Solid Waste 

Environmental Protection Agency

Marquette University School of Dentistry Dental Amalgam Recycling
BE THE DIFFERENCE!

To Teach, Build and Highlight Responsible Dentistry

Marquette University School of Dentistry Dental Amalgam Recycling
Presentation Topics

• Brief history of amalgam

• Extent of amalgam use in the US 

• Current government regulation

• Environmental fate and transport mechanisms of amalgam 

• Amalgam (Hg) bias by the general population

• Professional and environmentally responsible amalgam 

management techniques

Marquette University School of Dentistry Dental Amalgam Recycling
HISTORY OF AMALGAM

To Teach, Build and Highlight Responsible Dentistry

Marquette University School of Dentistry Dental Amalgam Recycling
History of Amalgam

Marquette University School of Dentistry Dental Amalgam Recycling

• A Chinese medical text 

mentions using a “silver 

paste”, a type of 

amalgam, to fill teeth in 

the 7th century.1
History of Amalgam

• b. 1678 – d. 1761

• The Age of Enlightenment

• Between 1650 and 1800 

the Science of Modern 

Dentistry developed

• Le Chirurgien Dentiste 

published in 1728

• He advocated the use of 

lead (plombagel) to fill 

cavities.

Marquette University School of Dentistry Dental Amalgam Recycling
History of Amalgam

Joseph Fox 

• b. 1775 – d. 1816 

• one of the most highly regarded English Dentists of his time.

• In 1803 he created “Fusible Metal”. 

• This metallic liquid filling material (bismuth, lead, and tin) 

when put into the cavity form and cooled, would solidify and 

replicate the shape of the cavity.

• The problem was the relatively high melting point 

– equivalent to that of water 

– a less than favorable experience. 

Marquette University School of Dentistry Dental Amalgam Recycling
History of Amalgam

• Thomas Bell

– b. 1792 – d. 1880 

– Fox’s successor at Guy’s 

Hospital

– Around 1826 he invented an 

amalgam of coin silver and 

mercury which had a much 

lower melting point than Fox’s 

metal. (Frenchman August 

Taveau also came up with a 

similar discovery around the 

same time). 

– It remained soft during the 

procedure and was much more 

comfortable to the patient.

Marquette University School of Dentistry Dental Amalgam Recycling
History of Amalgam

• Crawcour brothers 

– In 1833 introduced Taveau’s amalgam in New York

• They went from town to town 

placing Royal Mineral 

Succadaneum (Taveau’s

Amalgam) for all of the people 

who could not afford the Royal 

Mineral (Gold).

• They did a remarkable job of 

advertising.

– As well as of not removing decay 

before they filled the teeth.

• Most of the fillings fell out or the 

teeth split apart from the 

expansion of the amalgam a few 

days after they left the town.

Marquette University School of Dentistry Dental Amalgam Recycling
History of Amalgam

• The Amalgam War

– Local dentists organized to fight the use of this “execrable material by 

swindling villains”

– Crawcour brothers forced to flee America

• In 1843, the American Society of Dental Surgeons (ASDS) 

began a crusade to fight the use of amalgam

• In 1845, the ASDS passed a resolution compelling every 

member not to use amalgam

• In 1850, the ASDS rescinds its pledge requirement

• In 1855, the ASDS disbands

– If you can’t beat them, join them

Marquette University School of Dentistry Dental Amalgam Recycling
History of Amalgam

• What ended the Amalgam War?

– Professional and consumer demand 

– Amalgam was here to stay.

• In 1859, the leaders of the profession regrouped to form the 

American Dental Association.

• Between 1860 and 1890 many experiments were done to 

improve Amalgam filling materials.

Marquette University School of Dentistry Dental Amalgam Recycling
History of Amalgam

• G.V. Black developed a 

“good and workable” 

amalgam in 1895

– He believed amalgam should 

consist of 67% silver, 27% tin, 

5% copper, and 1% zinc 

• Use of amalgam gradually 

won acceptance as a cost 

effective way to restore 

teeth

Marquette University School of Dentistry Dental Amalgam Recycling
Amalgam Composition

• Modern day dental 

amalgam

– usually referred to as a 

“silver filling” by patients 

– manufactured product 

containing two nearly equal 

parts by weight. 

• First part 

– a powder containing silver, 

tin, copper, zinc and other 

metals

• Second part

– liquid mercury (Hg). 

Marquette University School of Dentistry Dental Amalgam Recycling
Amalgam Composition

Marquette University School of Dentistry Dental Amalgam Recycling
GOVERNMENT REGULATION

To Teach, Build and Highlight Responsible Dentistry

Marquette University School of Dentistry Dental Amalgam Recycling
Amalgam: An FDA Regulated 

Medical Device

• Dental amalgam is a dental device regulated by the Food and Drug 

Administration (FDA).

– Specifically, it is regulated by the Center for Devices and Radiological 

Health (CDRH). 

• Since the early 90’s, the use of amalgam has been reviewed by the 

FDA, CDC, and NIH looking for a link between amalgam and health 

problems.

– To date, there are no studies that show it is harmful to adults or children.

Marquette University School of Dentistry Dental Amalgam Recycling
Amalgam: An FDA Regulated 

Medical Device

• In September 2006, an FDA Advisory Committee met to discuss and make recommendations 

to FDA on its draft white paper regarding the potential adverse health risks associated with 

exposure to mercury in dental amalgam. 

• The panel deliberated on a series of questions that FDA had posed on its draft white paper 

review of the amalgam literature.

– The majority of the panel believed that no conclusion could be drawn because the evidence was 

often contradictory and that conclusions based on a limited search should not be made.

– Some believed that the paper was limited and scope and had knowledge gaps particularly regarding 

exposure limits 

– Lack of knowledge concerning effects on pregnant women, children, and those who are sensitive to 

Hg.

• The joint committee concluded with personal recommendations by the members. They 

included the following:

– Consider informed consent for patients receiving amalgam 

– Consider labeling changes restricting its use in pregnant woman and children 

– Do not make any rash decisions by having the pubic remove their amalgams because it appears that 

this problem may affect only a small segment of the population. 
Amalgam Waste: An EPA

Regulated Product

• The Environmental Protection Agency (EPA) regulates any 

waste generated from amalgam preparation and use. 

• At the federal level, the EPA is not seeking to eliminate the 

future use of dental amalgam. 

• Their goal:

– to teach and encourage the proper management of wastes generated 

from its use. 

Marquette University School of Dentistry Dental Amalgam Recycling
Amalgam Waste: An EPA

Regulated Product

• Examples of amalgam waste: 

– Non contact amalgam

• Excess left over after procedure

– Contact amalgam

• Has been in contact with human....extracted teeth, carving scrap, 

traps, filters

– Chairside traps

– Vacuum pump filters

– Amalgam sludge

• Mix of liquid and solid collected within filters and traps

– Amalgam capsules

• Used and unused 

Marquette University School of Dentistry Dental Amalgam Recycling
EXTENT OF AMALGAM USE IN THE 

UNITED STATES

To Teach, Build and Highlight Responsible Dentistry

Marquette University School of Dentistry Dental Amalgam Recycling
Decline of Hg Containing Products

• Since 1980 mercury usage in products has continued to 

decline substantially over the years – a decrease of 83%.

 

• This reduction in use was due in large part to legislation and 

regulatory standards for mercury usage in batteries and to 

EPA’s regulatory ban on mercury in paint. 

• Mercury use in products accounted for an estimated 245 

metric tons in 2001. Mercury usage in the form of dental 

equipment and supplies was 34 metric tons or 14% of the 

total.

Marquette University School of Dentistry Dental Amalgam Recycling
Decline of Hg Containing Products

245 Metric Tons 

Norfolk & Western Y6b

34 Metric Tons 

US Army HMMWV

Marquette University School of Dentistry Dental Amalgam Recycling

x 14! 

539,000 lbs Total Hg Usage 75,000 lbs of Dental Hg Usage
Extent of Amalgam Use In The US and 

Its Impact on Water Bodies

• The use of dental amalgam has declined in the past two 

decades, however, it continues to be placed.

• US dentists placed 200 million restorations in 19901.

– 96 million were amalgam restorations

– 38% reduction from 1979

• Decrease in caries rate

• Improved substitute materials

• US dentists placed 66 million amalgam restorations in 1999. 

• There are currently 201,604 licensed dentists in the U.S.2

– One would assume most place and/or remove amalgam restorations

Marquette University School of Dentistry Dental Amalgam Recycling
Extent of Hg Use In The US and 

Its Impact on Water Bodies

• The EPA estimates that the average dentist contributes 0.1 to 0.3 

grams of mercury in the form of amalgam per day to 

wastewater. 

• Amount of amalgam waste is .45 mg per procedure.1 

– Total of non contact scrap and waste from carving.

• A report released in 2002 by the National Association of Clean 

Water Agencies (NACWA) indicated that dental clinics are the 

largest single source of mercury in wastewater.2

Marquette University School of Dentistry Dental Amalgam Recycling
Extent of Hg Use In The US and 

Its Impact on Water Bodies

• Products containing Hg sold in U.S.

– Switches & Relays – 55.1%

– Dental Amalgam – 30.7%

– Lamps – 18.4%

– Thermostats – 14.3%

– Measuring Devices – 4.9%

– Other – 3.5%

– Batteries – 2.6%

– Laboratory & Chemical Uses – 1.01%

Marquette University School of Dentistry Dental Amalgam Recycling
Extent of Hg Use In The US and 

Its Impact on Water Bodies

• Among these products containing mercury, dental amalgam is a 

focus of concern. 

• Relative to other sectors, dentists use large quantities of the 

metal in fillings, and they generate large amounts of mercurycontaining waste. 

• This waste is easy to capture

– inexpensive collection systems can collect up to 99 percent of dental 

mercury. 

– In the United States, relatively few dental offices use these systems.

Marquette University School of Dentistry Dental Amalgam Recycling
Why Is Dental Amalgam Still 

Being Used?

• Relatively easy to place

• Low cost

• Good resistance to compressive forces especially 

for posterior teeth.

• Insurance plans have traditionally covered 

placement procedure

• No current, adequate substitute

– If amalgam were banned, US dental costs would rise 

$8.2 billion in the first yr alone1

– 10% of all current dental expenditures

Marquette University School of Dentistry Dental Amalgam Recycling
Past Management Practices = More 

Pressure on Dentists Today

• Despite its continued use, management of amalgam waste 

has created substantial environmental contamination and has 

created more pressure on the industry to recycle amalgam to 

prevent it from getting into the environment.

• In 2003, half of the state legislatures in the country as well as 

the United States Congress introduced bills to protect the 

public from mercury.1

• Many states have already mandated the use of specific 

technologies to control the amount of amalgam reaching the 

environment from the dental office.

Marquette University School of Dentistry Dental Amalgam Recycling
Best Management Practices

• In March 2004, the 

American Dental 

Association released “Best 

Management Practices for 

Amalgam Waste” 

– A set of guidelines about 

recycling amalgam wastes. 

– Stresses recycling of amalgam 

collected in the dental office.

– No mention of installing 

amalgam separators to 

remove amalgam particles 

from wastewater.

Marquette University School of Dentistry Dental Amalgam Recycling
Best Management Practices

• In October 2007, the American Dental Association revised “Best 

Management Practices for Amalgam Waste” 

– Essentially the same except it mentions:

• Amalgam separators 

– Select an amalgam separator that complies with ISO 11143. 

– Follow the manufacturer’s recommendations for maintenance and recycling 

procedures. 

• For information on amalgam separators see: 

– “Laboratory evaluation of amalgam separators” 2002:133;577-89. 

– “Evaluating amalgam separators using an international standard” 

2006:137;999-1005. 

– “Purchasing, installing and operating dental amalgam separators: Practical 

issues” 2003 134: 1054-65. 

Marquette University School of Dentistry Dental Amalgam Recycling
States Requiring Separators

• One manufacturer tallies its 

separator sales in those 

states that don’t require 

them: (2003 data)

– Wisconsin – 2 

– Texas – 1

– New York – 2

– New Jersey – 0.1

• Its sales in Connecticut 

which does require them:

– exceed 600.

Marquette University School of Dentistry Dental Amalgam Recycling
States Requiring Separators

 Connecticut, Maine, Massachusetts, New 

Hampshire, New York, Vermont, Rhode Island 

(eastern half of state), Vermont

 VT and CT include separators in BMPs and require 

dentists to implement BMPs

 King County Washington (soon to be the entire 

state)

 New Jersey is working on a requirement for 

separators

 Majority of Wisconsin – mandating by 12.31.08

Marquette University School of Dentistry Dental Amalgam Recycling
AMALGAM BIAS

To Teach, Build and Highlight Responsible Dentistry

Marquette University School of Dentistry Dental Amalgam Recycling
Major Studies Show Impact on 

Water Quality From Dental Amalgam 

• Recent studies by the New York Academy of Sciences indicate as much as 

40% of the New York/New Jersey Harbor mercury loadings are from dental 

offices with an input of nearly 4000 Kg/yr. (Pollution Prevention and Management 

Strategies For Mercury in the New York/New Jersey Harbor, May 14, 2002. Allison L. C. de 

Cerreño, Marta Panero, and Susan Boehme. New York Academy of Sciences. New York, New 

York) 

• The National Association of Clean Water Agencies (NACWA) estimated 

that 36 percent of mercury entering publicly owned treatment works 

(POTWs) is discharged from dental offices due to mercury from its waste 

amalgam. 

• Mercury discharges from dental offices far exceeded all other commercial 

and residential sources, each of which was below 10 percent. 

Marquette University School of Dentistry Dental Amalgam Recycling
The Problem with Mercury

• Mercury is persistent, bio-accumulative, and toxic and is 

responsible for significant environmental degradation around 

the world.

• Although its use in most product applications does not 

present a risk, the subsequent disposal of any product 

containing mercury does.

– Amalgam is no different. 

Marquette University School of Dentistry Dental Amalgam Recycling
The Problem with Mercury

Three types of Mercury:

• Elemental Hg

– Heavy, odorless, silver colored liquid

– Inhalation is the main source of toxicity

• Hg well absorbed by lungs

– Need long term exposure or one large exposure

• Inorganic Hg

– Known as Mercuric salts...i.e. mercuric chloride, mercuric iodide, cinnabar

– Found in many folk medicines

– Corrosive and damage the kidneys

– Long term use can cause skin irritation, staining, and nerve damage

• Organic Hg

Marquette University School of Dentistry Dental Amalgam Recycling
The Problem with Mercury

• Organic Hg

– Found in fungicides and antibacterials (mercurichrome)

– The main source of Hg poisoning is ingestion

• Small ingestions rarely cause problems

• Large ingestions or long term ingestions are

• Hg primarily found in fish

– Organic concentrations can be 1000x higher in the fish 

than in the surrounding water

– Very damaging compounds that can attack all body 

systems

Marquette University School of Dentistry Dental Amalgam Recycling
Methylmercury: More Risky In 

The Environment

• The EPA is most concerned about methylmercury in the 

environment.

– It is a form of mercury which is more potent and more 

bioaccumulative than other forms of mercury. 

– Methylmercury is also the form to which humans are primarily 

exposed.

• Inorganic Hg has a high affinity for particles,

– therefore, the fate of most inorganic mercury in aquatic systems is 

sedimentation.

• ......Methylmercury, in contrast, tends to be more soluble

because of its affinity for organic compounds.

Marquette University School of Dentistry Dental Amalgam Recycling
Methylmercury: How Is It Formed?

• When dental amalgam is released to the environment, the 

mercury component is transformed into methylmercury by 

microbial action.

• Methylation is a product of very complex processes that 

transform mercury into more reactive species. 

Marquette University School of Dentistry Dental Amalgam Recycling
Methylmercury: How Is It Formed?

Marquette University School of Dentistry Dental Amalgam Recycling
The Impact of Methylmercury 

In The Environment

• Once formed, this new 

mercury compound is taken 

up more readily by aquatic 

organisms such as fish, 

particularly in waters higher 

in acidity. 

• Methylmercury uptake by 

fish leads to fish advisories of 

which there are 41 

nationwide. 

Marquette University School of Dentistry Dental Amalgam Recycling
ENVIRONMENTAL FATE & 

TRANSPORT MECHANISMS

To Teach, Build and Highlight Responsible Dentistry

Marquette University School of Dentistry Dental Amalgam Recycling
How Does Amalgam Waste 

Reach the Environment?

• From POTW’s connected to the dental office which receive 

amalgam through office piping and sewer discharges....

• From medical waste companies who pick up red bags at 

dental offices containing amalgam waste and subsequently 

treat the medical waste in incinerators.....

• From landfills which receive amalgam waste from disposal 

companies which take waste from dentists who place it in 

office municipal trash....

Marquette University School of Dentistry Dental Amalgam Recycling
Publically Owned Treatment Works

• Dental Amalgam Waste

– Into Vacuum line

– Not captured by office traps

– Released to the sewer 

– Into (POTWs) 

• Mercury removal in POTWs is 

about 90.16%.* Thus, because 

removal is not 100%, a fraction of 

mercury is discharged to rivers and 

streams.

*(EPA. 1982. Effluent Guidelines 

Division. Fate of Priority Pollutants 

in Publicly Owned Treatment 

Works. EPA 440/1-82/303. 

Washington, DC.)

Marquette University School of Dentistry Dental Amalgam Recycling
Medical Waste Incinerators 

• Dental Amalgam Waste

– Into red medical bags 

– Treated by medical waste 

companies by incinerators 

which are not designed to 

handle the mercury 

component of amalgam.

– Hg emitted to the atmosphere 

through the stacks. 

– Airborne Hg deposited into 

water bodies. 

– Thus, your amalgam waste 

from your office will be blown 

into the air if you place it in red 

medical red for disposal.

Marquette University School of Dentistry Dental Amalgam Recycling
Landfills

• Dental Amalgam Waste

– Into garbage

– Goes to landfill

– Landfill leachate enters 

groundwater

– Thus, your amalgam waste 

could reach groundwater if you 

dispose of it in the trash.

Marquette University School of Dentistry Dental Amalgam Recycling
ENVIRONMENTALLY RESPONSIBLE 

PRACTICES

To Teach, Build and Highlight Responsible Dentistry

Marquette University School of Dentistry Dental Amalgam Recycling
Strategies For Proper Amalgam Waste 

Management in Your Office

At a minimum, EPA recommends four specific actions to manage your amalgam 

waste. The first letters of each action form the acronym G.R.I.T.

1. Grey Bag It.....Discard any amalgam wastes into a grey bag. Never dispose of 

dental amalgam wastes in medical red bags or in your office trash containers. 

2. Recycle It.....Select a responsible dental amalgam recycler who will manage your 

waste amalgam safely to limit the amount of mercury which can go back into the 

environment.

3. Install It......Install an amalgam water separator in the office to capture up to 99% of 

the mercury leaving a dental office through drains. This is the KEY to success.

4.Teach It.....Educate and train staff about the proper management of dental 

amalgam in the office.

Marquette University School of Dentistry Dental Amalgam Recycling
Grey Bag It....

Marquette University School of Dentistry Dental Amalgam Recycling

• Environmentally 

responsible amalgam 

waste control begins in 

the dental office.

• The ADA, EPA, and 

industry leaders (Sept 

2006) developed a 

volunteer standard thru 

ANSI (American National 

Standards Institute)

• The EPA refers to this as 

“Grey Bag” collection
Grey Bag It....

For Amalgam Waste For Amalgam Capsules

Marquette University School of Dentistry Dental Amalgam Recycling
Recycle It

• Most important step:

– Selection of a responsible company to manage your waste once you 

have properly controlled it in your office. 

• It makes no sense to handle your waste properly and then 

turn it over to someone who can’t properly manage Hg 

waste.

• Mercury cannot be destroyed, so waste managers must rely 

on various methods to treat or recover it, depending on:

– the mercury species present

– its concentration

– the waste matrix or media involved. 

Marquette University School of Dentistry Dental Amalgam Recycling
Recycle It 

• Select a company which is subject to regulatory oversight 

established through a formal Subpart B permit process under 

the Resource Conservation and Recovery Act.

• One of the most effective processes to handle mercury wastes 

is called “retorting.” 

– Process especially designed to capture the mercury in waste amalgam. 

– Retorting operations separate the mercury from the rest of the waste 

stream and condense it for recovery. 

• All major retorters in this country have Subpart B permits as 

hazardous waste treatment and storage facilities. 

Marquette University School of Dentistry Dental Amalgam Recycling
Recycle It 

• Bottom Line:

– The end point to responsible waste management 

is ensuring that mercury is not released to the 

environment during or after treatment has 

occurred. 

Marquette University School of Dentistry Dental Amalgam Recycling
Install It

Installing An Amalgam Separator

 Removes amalgam from dental 

wastewater discharges prior to it 

leaving the office.

 It has been estimated that ~40% 

of Hg load to wastewater 

treatment plants comes from the 

dental office

 using separators will have an big impact on water quality.

 Separators vary in complexity, cost and efficiency. 

 Select one which will provide adequate removal based on the 

number of operatories in your 

practice. 

 Even “low tech” systems appear to be effective....

Marquette University School of Dentistry Dental Amalgam Recycling
Teach It

• Educate and train your staff.

• You can know everything 

about proper amalgam 

management....but does your 

staff? 

– Who throws amalgam capsules 

away? 

– Who prepares amalgam for 

placement?

• It is the responsibility of 

everyone to manage 

amalgam properly.

Marquette University School of Dentistry Dental Amalgam 

Recycling
The Environmentally Aware Dentist Knows.....

• ....why

– dental amalgam (Hg) is a hazard to the environment.

• ....how

– dental amalgam waste reaches the environment.

• ....what

– you can do to minimize its release to the environment.

Marquette University School of Dentistry Dental Amalgam Recycling
THANK YOU!

Gary L. Stafford DMD

Program Director for General Dentistry

Marquette University School of Dentistry

gary.stafford@mu.edu

Marquette University School of Dentistry Dental Amalgam Recycling