# 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 7 th 

## 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!

75,000 lbs of Dental Hg Usage 539,000 lbs Total 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 1990 1



### .

– 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 mercury

containing 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 alone 1



### – 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. 

# G rey 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. 

# R ecycle 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. 

# I nstall 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. 

# T each 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