EPA-821-R-08-014 

Health Services Industry Detailed Study 

Dental Amalgam 

August 2008 
i

CONTENTS 

Page 

EXECUTIVE SUMMARY............................................................................................................... ES-1 

1. INTRODUCTION .................................................................................................................1-1 

2. PROFILE OF DENTAL INDUSTRY ........................................................................................2-1 

2.1 Number of Facilities ............................................................................................2-1 

2.2 Revenues and Employees ....................................................................................2-3 

2.3 Number of Companies .........................................................................................2-3 

2.4 Number of Small Businesses ...............................................................................2-4 

2.5 Ownership............................................................................................................2-5 

2.6 Discharge Information .........................................................................................2-5 

2.7 Financial Characteristics......................................................................................2-6 

2.7.1 Liquidity...................................................................................................2-6 

2.7.2 Profit Before Taxes..................................................................................2-6 

3. DENTAL MERCURY SOURCES AND ENVIRONMENTAL IMPACTS ........................................3-1 

3.1 Sources of Dental Amalgam in Wastewater from Dental Facilities....................3-2 

3.2 Environmental Impacts of Dental Mercury Discharges.......................................3-2 

3.3 Dental Mercury Treatment at POTWs.................................................................3-3 

4. CURRENT NATIONAL, STATE, AND LOCAL DENTAL MERCURY PROGRAMS......................4-1 

4.1 National Dental Amalgam Requirements and Guidance.....................................4-1 

4.1.1 Federal Requirements and Guidance .......................................................4-1 

4.1.2 American Dental Association Guidance..................................................4-3 

4.2 State Dental Amalgam Requirements and Guidance...........................................4-5 

4.2.1 State Mandatory Programs.......................................................................4-5 

4.2.2 State Dental Amalgam Guidance.............................................................4-9 

4.3 Local Dental Amalgam Requirements and Guidance..........................................4-9 

4.3.1 Local Dental Amalgam Requirements.....................................................4-9 

4.3.2 Local Dental Amalgam Voluntary Programs ........................................4-15 

4.4 Common Elements Found in State and Local Programs ...................................4-22 

5. EFFECTIVENESS AND COSTS OF DENTAL BMPS, INCLUDING AMALGAM 

SEPARATORS.....................................................................................................................5-1 

5.1 Treatment Efficiencies and Standards for Amalgam Separators .........................5-1 

5.1.1 Standards for Amalgam Separators .........................................................5-1 

5.1.2 Treatment Efficiencies.............................................................................5-2 

5.2 Impacts of Dental BMPs, Including Amalgam Separators, on POTW 

Influent.................................................................................................................5-4 

5.2.1 Summary of Dental BMPs.......................................................................5-4 

5.2.2 Summary of Case Studies ........................................................................5-5 

5.2.3 Considerations for Determining Impacts of BMPs on POTW 

Influent Mercury Levels ..........................................................................5-5 
CONTENTS (Continued) 

Page 

ii

5.3 Costs of Dental BMPs..........................................................................................5-9 

5.3.1 BMP Program Costs to State and Local Agencies...................................5-9 

5.3.2 Costs to Facilities.....................................................................................5-9 

5.3.3 Amalgam Recycling...............................................................................5-15 

6. DENTAL MERCURY PASS-THROUGH ANALYSIS................................................................6-1 

6.1 Number of Dentists..............................................................................................6-1 

6.2 Mercury Discharge from Amalgam Restorations and Amalgam Removal .........6-2 

6.3 Determining Baseline Mercury Discharge to POTWs.........................................6-3 

6.4 Potential Reduction from Installation of Amalgam Separators ...........................6-5 

6.5 Annualized Costs for Amalgam Separators.........................................................6-6 

6.6 Summary and Costs .............................................................................................6-7 

7. REFERENCES .....................................................................................................................7-1 
iii

LIST OF TABLES 

Page 

2-1 Number of Establishments by State (2005) ..................................................................... 2-1 

2-2 Number of Dental Laboratories and Offices.................................................................... 2-3 

2-3 Nationwide Summary by NAICS (2002)......................................................................... 2-3 

2-4 Number of Single-Unit and Multi-Unit Firms (2005) ..................................................... 2-4 

2-5 Small Businesses (2005).................................................................................................. 2-4 

2-6 2006 Current Ratio of Assets to Liability (Liquidity) ..................................................... 2-6 

2-7 2006 Profit Before Taxes (%).......................................................................................... 2-7 

3-1 Mean Concentrations of Mercury Species in Dental Wastewater ................................... 3-2 

4-1 ADA BMPs for Dental Amalgam.................................................................................... 4-4 

4-2 Summary of Elements of State Requirements ................................................................. 4-5 

4-3 Best Management Practices by State ............................................................................... 4-7 

4-4 Voluntary BMPs by State .............................................................................................. 4-10 

4-5 Summary of Elements of Local Requirements .............................................................. 4-12 

4-6 Best Management Practices by Municipality ................................................................ 4-13 

4-7 Summary of Voluntary Programs for Reducing Dental Amalgam Releases to 

Wastewater..................................................................................................................... 4-16 

4-8 Non-Dental Mercury Sources ........................................................................................ 4-23 

4-9 Compliance Requirements from State and Local Mandatory Programs ....................... 4-25 

5-1 Effectiveness of Amalgam Separators............................................................................. 5-3 

5-2 Impact of BMPs on Mercury Discharged to POTW........................................................ 5-6 

5-3 Cost of BMP Program to State and Local Agencies........................................................ 5-9 

5-4 Cost of Purchasing, Operating and Maintaining Amalgam Separators ($2008) a ......... 5-11 

5-5 Estimated Purchase, Installation, and O&M Costs of Amalgam Separator ($2008)..... 5-14 

5-6 Summary of Cost Estimates........................................................................................... 5-14 
LIST OF TABLES (Continued) 

Page 

iv

5-7 Estimated Annual Cost for Amalgam Separators by Size of Dental Office ($2008) .... 5-15 

6-1 Estimate of Total Number of Dentists ............................................................................. 6-2 

6-2 Determining the Total Mercury Discharge from Amalgam Restorations ....................... 6-2 

6-3 Determining the Total Mercury Discharge from Amalgam Removals ........................... 6-2 

6-4 Determining the Baseline Mercury Discharge to Wastewater......................................... 6-4 

6-5 Potential Reductions of Mercury to POTWs from Mandatory Installation of 

Amalgam Separators........................................................................................................ 6-5 

6-6 Calculation of Cost .......................................................................................................... 6-7 

6-7 Summary of Calculations................................................................................................. 6-7 

6-8 Number of Dental Facilities and Amalgam Separator Use by State................................ 6-8 
ES-1 

EXECUTIVE SUMMARY

 Across the United States, many States and municipal wastewater treatment plants 

(publicly owned treatment works (POTWs)) are working toward the goal of reducing discharges 

of mercury to POTWs. Many studies have been conducted in an attempt to identify the sources 

of mercury entering these POTWs. According to the 2002 Mercury Source Control and Pollution 

Prevention Program Final Report prepared for the National Association of Clean Water 

Agencies (NACWA), dental clinics are the main source of mercury discharges to POTWs. A 

study funded by the American Dental Association (ADA) estimated in 2003 that 50 percent of 

mercury entering POTWs was contributed by dental offices (Vandeven and McGinnis, 2005). 

EPA estimates that dentists discharge approximately 3.7 tons of mercury each year to POTWs 

(see Section 6 of this document). 

 Sources of amalgam in dental wastewater include the placement of and removal of 

amalgam fillings (restorations). Of the dental amalgam constituents, mercury is of greatest 

concern to human health because it is a persistent bioaccumulative toxic chemical. Mercury can 

bioaccummulate three to ten times across each trophic level of the food chain. The major route 

for human exposure to mercury in wastewater discharges is through the consumption of 

mercury-contaminated fish. 

 Mercury discharged in dental wastewater is present in many forms, including elemental 

mercury bound to amalgam particulate, inorganic (ionic) mercury, elemental mercury, and 

organic mercury (monomethyl mercury (MeHg)) (Stone, 2002). The vast majority (>99.6 

percent) of dental mercury discharges are in solid form (elemental mercury bound to amalgam 

particulate). While dissolved mercury composes a small portion of total mercury in dental office 

wastewater, some studies have indicated high levels of dissolved mercury in dental wastewater, 

and that dissolved mercury concentrations can be high enough to violate local mercury discharge 

limits (Stone, 2004). 

 Dissolved mercury is a concern because it can be converted to MeHg by bacteria, such as 

Desulfobacteraceae and Desulfovibrionaceae that are present in wastewater (ACS, 2008). 

Researchers have detected concentrations of MeHg in dental wastewater that are orders of 

magnitude higher than background MeHg concentrations measured in environmental samples 

(i.e., open oceans, lakes, and rainfall) (Stone, 2002). Although the MeHg concentrations are 

small compared to total mercury concentrations in dental wastewater, MeHg is particularly toxic 

to humans due to its ability to bioaccumulate in fish (WI DNR, 1997). 

 EPA estimates there are approximately 120,000 dental offices that use or remove 

amalgam in the United States – almost all of which discharge their wastewater exclusively to 

POTWs. Most dental offices currently use some type of basic filtration system to reduce the 

amount of mercury solids passing into the sewer system. However, best management practices 

and the installation of amalgam separators, which generally have a removal efficiency of at least 

95 percent, have been shown to reduce discharges even further. A 2002 study funded by the 

National Association of Clean Water Agencies (NACWA) (See: DCN: 04225) concluded that 

the use of amalgam separators results in reductions in POTW influent concentrations and 

biosolids mercury concentrations. However, the NACWA study found that the use of amalgam 

separators does not always result in reductions in POTW effluent. Since the mercury in dental 

amalgam often reaches POTWs as larger particulates, it is likely to be removed in the grit 
ES-2 

chambers or with the biosolids and not be discharged with the effluent. Thus, reductions in 

dental office amalgam discharges may result in reductions in the mercury content of POTW 

sludges (grit and biosolids), and may not result in reductions in mercury concentrations in 

POTW effluent. 

 ADA provides guidance documents for its members and the general public for the 

management and disposal of dental amalgam and amalgam waste. These include information 

regarding proper recycling of amalgam waste and practical guidelines for integrating best 

management practices (BMPs) into dental practices. On October 2, 2007, the ADA updated its 

BMPs to include the use of amalgam separators. ADA also provides advice for successful 

integration of BMPs into practices and offices, a directory of national dental waste recyclers, 

recommendations for safe preparation and placement of amalgam restorations, safety 

information for managing mercury spills, and advice on the purchase, installation and operation 

of amalgam separators (ADA, 2007). The ADA-defined BMPs are recognized as the industry 

standard. Table 4-1 of this document lists the ADA BMPs for amalgam waste. 

 State and local governments have implemented mandatory and voluntary programs to 

reduce dental mercury discharges. Specifically, 11 States and at least 19 localities have 

mandatory pretreatment programs that require the use of dental mercury amalgam separators. 

Additionally, at least four States and six POTWs have voluntary programs to reduce mercury 

discharges from dental offices though success rates for the voluntary programs vary greatly. 

 In this document, EPA has compiled information on current mercury discharges from 

dental offices, best management practices (BMPs), and amalgam separators. For amalgam 

separators, EPA has looked at the frequency with which they are currently used; their 

effectiveness in reducing discharges to POTWs; and the capital and annual costs associated with 

their installation and operation. EPA has also conducted a POTW pass-through analysis on 

mercury for the industry. 

 EPA does not think national, categorical pretreatment standards for dental mercury 

discharges are appropriate at this time. While this is a possibility for the future, EPA has 

identified a number of successful voluntary programs demonstrating that there are opportunities 

for pollution prevention and adoption of BMPs without federal regulation. Moreover, the dental 

industry is working towards voluntarily reducing its mercury discharges. Also, due to mercuryfree fillings and improved overall dental health, the use of mercury in dentistry is decreasing in 

the U.S. 
1-1 

1. INTRODUCTION

 Under the Clean Water Act (CWA), EPA establishes national regulations (called effluent 

limitations guidelines and standards) to reduce discharges of pollutants from industries to surface 

waters and publicly owned treatment works (POTWs). Section 304(g) and 307(b) of the CWA 

requires EPA to review industries consisting entirely or almost entirely of indirect discharging 

facilities that are not currently subject to pretreatment standards to identify potential candidates 

for pretreatment standards development. This includes pretreatment standards for categories of 

dischargers that discharge pollutants not susceptible to treatment by POTWs or that would 

interfere with the operation of POTWs. Using available data, EPA reviews the types of pollutants 

in an industry’s wastewater. Then, EPA reviews the likelihood of those pollutants to pass 

through a POTW and finally considers whether the pollutant discharges are already adequately 

controlled by general pretreatment standards and/or local pretreatment limits. 

 Every other year EPA publishes a final Effluent Guidelines Program Plan as required by 

CWA Section 304(m). The plan addresses both categories with large numbers of direct 

discharging facilities and categories consisting entirely or almost entirely of indirect discharging 

facilities. EPA publishes a draft plan to give the public an opportunity to comment on the plan 

before it is final. EPA selected the health services industry for further analysis in the 2006 Plan 

(EPA, 2006), based in part on public comments concerning the discharge of mercury from dental 

offices and dental laboratories. EPA’s study addresses the following questions: 

• What are the current industry practices for disposing of dental mercury, to what 

extent are each of these practices applied, and what factors affect the use of these 

practices? 

• What are the federal, state, or local requirements or guidance for disposal of 

dental mercury? 

• How are control authorities currently limiting dental mercury discharges? 

• Do POTWs report pass-through or interference problems related to dental 

mercury discharges? 

• What technologies are available (1) as alternatives to wastewater disposal and (2) 

to control discharges? How effective are these technologies? 

• What best management practices (BMPs) are used as alternatives to wastewater 

disposal and/or to control discharges? How effective are these practices? 

• What are the costs of the identified technologies and/or BMPs? 

 This report describes EPA’s analysis of dental mercury discharges and is organized into 

the following sections: 
1-2 

• Section 2 provides a preliminary profile of the dental industry that includes the 

number of dental offices and laboratories, the number of small businesses, 

discharge information, and financial characteristics; 

• Section 3 discusses sources of dental mercury and environmental impacts; 

• Section 4 describes national, state, and local mandatory and voluntary programs 

to reduce mercury wastewater discharges from dental offices; 

• Section 5 describes the effectiveness and costs for dental mercury BMPs and 

amalgam separators; and 

• Section 6 describes EPA’s estimate of the potential reductions in dental mercury 

discharges to receiving streams following installation of amalgam separators. 
2-1 

2. PROFILE OF DENTAL INDUSTRY

 This section presents industry profile information using the North American Industry 

Classification System (NAICS) codes and the Standard Industrial Classification (SIC) codes. The 

U.S. Census Bureau classifies information by NAICS codes and EPA classifies discharge 

information (TRI and PCS database information) by SIC code. 

 Dental laboratories fall under NAICS 339116, with the definition: 

“This U.S. industry comprises establishments primarily engaged in manufacturing 

dentures, crowns, bridges, and orthodontic appliances customized for individual 

application.” http://www.census.gov/epcd/ec97/def/339116.TXT

There is 100 percent correspondence between NAICS 339116 and SIC 8072 (Census, 2007a). 

 Offices of dentists fall under NAICS 621210, with the definition: 

“This industry comprises establishments of health practitioners having the degree of 

D.M.D. (Doctor of dental medicine), D.D.S. (Doctor of dental surgery), or D.D.Sc. 

(Doctor of dental science) primarily engaged in the independent practice of general or 

specialized dentistry or dental surgery. These practitioners operate private or group 

practices in their own offices (e.g., centers, clinics) or in the facilities of others, such as 

hospitals or HMO medical centers. They can provide either comprehensive preventive, 

cosmetic, or emergency care, or specialize in a single field of dentistry.” 

http://www.census.gov/epcd/ec97/def/621210.TXT

There is 100 percent correspondence between NAICS 621210 and SIC 8021 (Census, 2007b). 

2.1 Number of Facilities

Table 2-1 provides a comprehensive listing of establishments by state for NAICS 339116 

(Dental Laboratories) and 621210 (Dental Offices). Based on 2005 County Business Patterns 

data, there are 7,225 dental laboratories and 122,918 dental offices operating nationwide 

(Census, 2005a). According to the 2002 Census, there were 7,096 dental laboratories and 

118,305 dental offices. According to the 1997 Census, there were 7,609 dental laboratories and 

114,178 dental offices (Johnston, 2005). Table 2-2shows the industry changes over time. 

Table 2-1. Number of Establishments by State (2005) 

State NAICS 339116 Dental Laboratories NAICS 621210 Dental Offices 

Alabama 107 1,417 

Alaska 16 307 

Arizona 153 2,209 

Arkansas 58 933 

California 1,011 19,005 

Colorado 153 2,366 

Connecticut 80 1,732 
2-2 

Table 2-1. Number of Establishments by State (2005) 

State NAICS 339116 Dental Laboratories NAICS 621210 Dental Offices 

Delaware 8 243 

District of Columbia 2 315 

Florida 566 6,733 

Georgia 247 3,024 

Hawaii 38 686 

Idaho 59 656 

Illinois 318 5,639 

Indiana 139 2,334 

Iowa 69 1,077 

Kansas 55 1,016 

Kentucky 73 1,586 

Louisiana 97 1,527 

Maine 27 478 

Maryland 108 2,483 

Massachusetts 113 3,050 

Michigan 208 4,353 

Minnesota 134 1,922 

Mississippi 47 846 

Missouri 144 2,153 

Montana 38 414 

Nebraska 49 790 

Nevada 73 883 

New Hampshire 32 560 

New Jersey 219 4,546 

New Mexico 38 593 

New York 469 9,017 

North Carolina 228 2,720 

North Dakota 10 259 

Ohio 232 4,357 

Oklahoma 71 1,325 

Oregon 143 1,825 

Pennsylvania 216 5258 

Rhode Island 30 412 

South Carolina 63 1,368 

South Dakota 18 267 

Tennessee 128 2,110 

Texas 377 7,597 

Utah 117 1,418 

Vermont 18 263 

Virginia 177 2,845 

Washington 276 3,183 
2-3 

Table 2-1. Number of Establishments by State (2005) 

State NAICS 339116 Dental Laboratories NAICS 621210 Dental Offices 

West Virginia 26 573 

Wisconsin 135 2,023 

Wyoming 12 222 

Total U.S. 7,225 122,918 

Source: Census, 2005a. 

Table 2-2. Number of Dental Laboratories and Offices 

NAICS Code SIC Code 

Number of Facilities 

in 1997 

Number of Facilities 

in 2002 

Number of Facilities 

in 2005 

339116: Dental 

Laboratories 

8072: Dental 

Laboratories 

7,609 7,096 7,225 

621210: Offices of 

Dentists 

8021: Offices and 

Clinics of Dentists 

114,178 118,305 122,918 

Sources: Johnston, 2005; Census, 2005a and b. 

2.2 Revenues and Employees

Table 2-3 lists the number of establishments, total revenues, total number of paid 

employees, average revenue, and average number of employees per establishment based on the 

2002 Census data. Average revenue and the average number of paid employees were determined 

by dividing total revenue and total paid employees by the total number of establishments, 

respectively. 

Table 2-3. Nationwide Summary by NAICS (2002) 

NAICS 

Number of 

Establishments 

Revenues 

($1,000) Paid Employees

Average Revenue 

($1,000) 

Employees per 

Establishment

339116: Dental 

Laboratories 

7,096 3,361,996 49,467 $473.79 6.97 

621210: Dental 

Offices 

118,305 71,102,922 743,628 $601.01 6.29 

Sources: Census, 2004 and 2005b. 

2.3 Number of Companies

Table 2-4 shows the number of establishments, total firms, and single- and multi-unit 

firms. For dental offices, the 2,461 multi-unit firms comprise 7,464 total establishments; 

specifically, there are 1,542 firms with two establishments, 402 firms with three to four 

establishments, 96 firms with five to nine establishments, and 41 firms with 10 or more 

establishments (Census, 2005c). 
2-4 

Table 2-4. Number of Single-Unit and Multi-Unit Firms (2005) 

NAICS Number of Firms 

Number of 

Establishments Single-Unit Firms Multi-Unit Firms

339116: Dental Laboratories 6,925 7,096 — — 

621210: Dental Offices 113,302 118,305 110,841 2,461 

Sources: Census, 2004 and 2005c. 

2.4 Number of Small Businesses

Table 2-5 lists the Small Business Administration (SBA) size standard for each NAICS 

industry and the number of establishments that meet these criteria. Dental laboratories have a 

size standard of 500 employees, while dental offices have a size standard of $6.5 million in 

average annual receipts (SBA, 2006). 

Table 2-5. Small Businesses (2005) 

NAICS Size Standard Total 

Definitely 

Small 

Possibly 

Small 

Best Estimate 

Small % Small 

339116: Dental 

Laboratories 

500 employees 7,096 7,086 — 7,086 99.9% 

621210: Dental 

Offices 

$6.5 million 118,305 107,258 9,805 116,843 98.8% 

Sources: Census, 2004 and 2005b. 

For dental laboratories, 2004 Census data list 7,086 establishments with fewer than 500 

employees and three establishments with more than 500 employees (Census, 2004).1 Thus, EPA 

determined that 7,086 firms are below the SBA threshold. Therefore, 99.9 percent of dental 

laboratories (NAICS 339116) qualify as small businesses. 

 EPA used year 2005 census reporting of receipts/revenue size of firms for dental offices. 

EPA classified an establishment in the “definitely small” category if it operated for the entire 

year and was in a revenue group where the upper limit was less than $6.5 million. The SBA size 

standard of $6.5 million falls within the range of the $5 million to $9.99 million revenue group. 

As a result, some but not all of the 149 establishments in that revenue group are small. EPA 

assumed that the companies were evenly distributed within the revenue group and prorated the 

company count accordingly. EPA estimated the number of “possibly small” establishments by 

multiplying 149 establishments by the ratio of the number of revenue units below the SBA 

threshold to the total number of revenue units in the range — 

($6.5 million - $5 million) ÷ ($9.99 million - $5 million) = 0.30 

 

1

 The discrepancy in the total number of establishments can be attributed to the fact that “some payroll and sales 

data for small single-establishment companies with up to 20 employees (cutoff varied by industry) were obtained 

from administrative records of other Government agencies rather than from census report forms. These data were 

then used in conjunction with industry averages to estimate statistics for these small establishments. This technique 

was also used for a small number of other establishments whose reports were not received at the time data were 

tabulated.” (Census, 2004) 
2-5 

— for a total of 45 establishments. EPA also included the number of companies that did not 

operate for all of 2005 (9,656) in the “possibly small” category in order not to underestimate the 

number of small entities. EPA assumed that the proportion of establishments that did not operate 

for an entire year and also qualified as small was equal to the proportion of establishments that 

qualified as small in the overall population: 98.8 percent, or 9,540 establishments (Census, 

2005b). 

 Based on the census information presented in this section, dental laboratories and dental 

offices are nearly all small businesses. 

2.5 Ownership

 Among the 118,305 total dental office establishments, 2002 Census data list 62,821 

corporations, 50,638 individual proprietorships, 4,778 partnerships, and 68 other forms of legal 

organization for dental offices. Ownership data for dental laboratories are not available at this 

time (Census, 2005d). 

2.6 Discharge Information

 Based on information contained in the TRI and PCS databases, dental facilities are small 

establishments, and few, if any, dental laboratories or dental offices/clinics are direct dischargers. 

No dental laboratories (SIC 8072) or dental offices/clinics (SIC 8021) reported releasing toxic 

chemicals to any media to TRI for 2004 (TRIReleases2004_v01). A facility is exempt from TRI 

reporting if it has less than 10 employees or if its chemical releases are below the TRI reporting 

thresholds; the TRI reporting threshold for mercury and mercury compounds is 10 pounds per 

year. 

 EPA’s PCSLoads2004_v02 database does not include pollutant loads for dental 

laboratories or dental offices/clinics. EPA reviewed PCS data contained on EPA’s Envirofacts 

Web page to verify that discharges from dental offices and dental laboratories were not reported 

to PCS. EPA identified nine dental offices/clinics that report to PCS (2007 Envirofacts 

information). Seven of these facilities were classified as minor dischargers. Permitting 

authorities are not required to report discharge information for minor facilities to PCS; therefore 

discharges for these seven facilities were not included in PCSLoads2004_v02. Two of the 

facilities that report to PCS were classified as major dischargers. However, the facilities did not 

have permit limits; therefore PCS does not contain measurement data for those facilities. EPA 

also identified one dental laboratory in PCS (2007 Envirofacts information). However, this 

facility is classified as a minor discharger with no discharge data in PCS, and therefore is not 

included in PCSLoads2004_v02. 

 The lack of information in TRI and PCS about dental industry wastewater discharges 

confirms that nearly all dental facilities are small, indirect dischargers. These results are 

consistent with EPA’s 2005 review of the dental industry, which also found little information for 

dental laboratories or dental offices in the 2000 TRI and PCS databases (Johnston, 2005). 
2-6 

2.7 Financial Characteristics

 This subsection describes the financial characteristics of the dental industry as measured 

by liquidity and profit before taxes. 

2.7.1 Liquidity 

Liquidity measures the ability of an industry to meet current financial obligations without 

having to convert assets to cash with a loss in value. A current ratio is calculated as total current 

assets divided by total current liabilities. Table 2-6 summarizes the current ratio for dental 

offices and dental laboratories for 2006 (RMA, 2007). Several differences between the groups 

are evident. With the exception of dental offices with sales in excess of $25 million, dental 

offices are illiquid. The overall current ratio for the industry in 2006 is 0.9 and the current ratio 

of dental offices with less than $25 million in revenues ranges from 0.7 to 0.9. This indicates 

that, at the time the balance sheet was constructed, the dental office owed more to its creditors 

than it had in assets. The historical data in RMA (2007) report a ratio of 0.8 in 2004. In contrast, 

the 2007 edition Almanac Financial of Business and Industrial Ratios indicates that dental 

offices are liquid and have sufficient assets to cover their current debts with a small cushion, and 

reports a ratio of 1.2 in 2004 (Troy, 2007). The 2007 Almanac is based on a sample of 62,347 

enterprises while RMA (2007) is based on 763 income statements. 

Table 2-6. 2006 Current Ratio of Assets to Liability (Liquidity) 

Revenues ($Millions) 

NAICS All $0–$1 $1–$3 $3–$5 $5–$10 $10–$25 >$25 

339116: Dental 

Laboratories 

1.7 — 2.7 — — — — 

621210: Dental 

Offices 

0.9 0.8 0.9 0.7 0.9 0.8 1.1 

Source: RMA, 2007. 

RMA (2007) has data for dental laboratories, while the Almanac (2007) does not. Dental 

laboratories show a much healthier current ratio of 1.7, indicating a greater ability to meet 

current obligations. (RMA does not show data when there are fewer than 10 annual statements in 

the subcategory.) 

2.7.2 Profit Before Taxes 

 Profit before taxes is calculated from an income statement, which is a one-year summary 

of costs and revenues. Table 2-7 shows a 10.4 percent profit before taxes for dental offices and a 

5.0 percent profit for dental laboratories. 
2-7 

Table 2-7. 2006 Profit Before Taxes (%) 

Revenues ($Millions) 

NAICS All $0–$1 $1–$3 $3–$5 $5–$10 $10–$25 >$25 

339116: Dental 

Laboratories 

5.0 — 5.8 — — — — 

621210: Dental 

Offices 

10.4 11.7 10.4 7.1 7.7 6.3 6.2 

Source: RMA, 2007. 
3-1 

3. DENTAL MERCURY SOURCES AND ENVIRONMENTAL IMPACTS

 The EPA Office of Compliance’s Sector Notebook for the Healthcare Industry identified 

mercury as the major pollutant of concern (POC) for wastewater discharges from dental facilities 

(see EPA-HQ-OW-2004-0032-0729). Sources of amalgam in dental wastewater include the 

placement of amalgam fillings and removal of amalgam during restorations. Other constituents 

of dental amalgam include metals such as silver, tin, copper, zinc, indium, and palladium. Of the 

dental amalgam constituents, mercury is of greatest concern to human health because it is a 

persistent, bioaccumulative, toxic chemical and can bioaccumulate three to ten times across each 

trophic level of the food chain. For wastewater mercury discharges, the major route for human 

exposure is the consumption of mercury-contaminated fish. 

 While mercury used in U.S. dental offices accounts for only a small percentage of the 

total mercury discharged to air and water each year, mercury in the form of dental amalgam is 

among the largest sources of mercury found in wastewater influent reaching POTWs. The 

American Dental Association (ADA) estimates that up to 50 percent of the mercury entering 

POTWs originates in dental offices (Vandeven and McGinnis, 2005). Recent data compiled from 

across the country indicate that varying amounts of the mercury in wastewater reaching POTWs 

originates from dental offices: 

• The East Bay Municipal Utility District (EBMUD) of Oakland, CA, estimates that 

dental offices account for 34 percent of the mercury influent loading to 

wastewater treatment plants (EBMUD, 2007); 

• Dental clinics contribute 11 to 14 percent of the mercury loading to local sanitary 

districts in Seattle, WA (Stone, 2004); 

• Dental clinics account for almost 50 percent of the mercury in wastewater in Palo 

Alto, CA (Palo Alto, 2007); and 

• A study by the Association of Metropolitan Sewerage Agencies (AMSA) — now 

the National Association of Clean Water Agencies (NACWA) — found that 

dental offices account for an average of 35 percent of the mercury influent to 

POTWs (AMSA, 2002). 

 Due to the increased concern regarding mercury in the environment, several U.S. 

industries have significantly decreased mercury usage since the 1980s (Vandeven and McGinnis, 

2005). Although dentists have also reduced their mercury use, as of 1999, amalgam was still 

widely used for restorations (66 million amalgam restorations in 1999) (Stone, 2004). ADA 

predicts that use of amalgam will continue to decrease due to various factors such as the 

introduction of improved filling material, overall decrease in tooth decay and earlier detection of 

tooth decay (EPA, 2007a). In 2007, TheWealthyDentist.com, a website and weekly newsletter 

for dentists, surveyed dentists to determine amalgam use. The survey found that 52 percent of 

dentists do not place amalgam fillings (The Wealthy Dentist, 2007). 

 The remainder of this section describes the wastewater sources of amalgam, 

environmental impacts of dental mercury, and treatment of dental mercury at POTWs. 
3-2 

3.1 Sources of Dental Amalgam in Wastewater from Dental Facilities

 Amalgam used in dental practices is typically 50 percent mercury mixed with a powder 

of silver, tin, copper, and sometimes zinc, indium, or palladium. Raw materials for dental 

amalgam are liquid mercury and a metal powder mixture, often supplied in capsules. In these 

capsules, the mercury and metal powders are kept separate until the dentist is ready to complete a 

restoration. When the dentist mixes (triturates) the mercury and powder, the mercury dissolves 

the powdered metals and a series of intermetallic compounds (e.g., Ag3Sn, Ag2Hg3, Sn8Hg) are 

formed (Vandewall, 2007). 

 Sources of amalgam in dental wastewater include waste amalgam from fillings and 

amalgam removed during restorations. When filling a cavity, dentists will always overfill the 

tooth cavity so they can carve the filling into proper shape (Columbia, 2005). The excess 

amalgam is typically rinsed into a chair-side drain. In addition to filling new cavities, dentists 

also remove old restorations that are worn or damaged. Removed restorations are also rinsed into 

the chair-side drain. 

3.2 Environmental Impacts of Dental Mercury Discharges

 Mercury discharged in dental wastewater is present in many forms, including elemental 

mercury bound to amalgam particulate, inorganic (ionic) mercury, elemental mercury, and 

organic mercury (monomethyl mercury, or MeHg) (Stone et al., 2002). Table 3-1 presents the 

mean concentrations of mercury species measured in wastewater samples collected at the chair. 

The vast majority (>99.6 percent) of dental mercury discharges are in solid form (elemental 

mercury bound to amalgam particulate). 

Table 3-1. Mean Concentrations of Mercury Species in Dental Wastewater 

Mercury Form Measured Concentration Percent of Total Mercury

Total mercury 21.438 milligrams/liter (ppm) 100.0% 

MeHg (monomethyl mercury) 277.74 nanograms/liter (ppt) 0.001296% 

Hg0 (elemental mercury) 24.06 micrograms/liter (ppb) 0.112231% 

Hg+2 (ionic mercury) 54 micrograms/liter (ppb) 0.251889% 

Hg0 (elemental mercury bound to 

amalgam particulate) 

21.360 milligrams/liter (ppm) 99.636160% 

Source: Stone, 2004.

 While dissolved mercury makes up a small portion of the total mercury in dental office 

wastewater, there is increasing interest in the causes of dissolution and the extent to which 

dissolved mercury is present in dental office wastewater. Some studies have indicated high levels 

of dissolved mercury in dental wastewater, and that dissolved mercury concentrations can be 

high enough to violate local mercury discharge limits (Stone, 2004). 

 Dissolved mercury is a concern because it can be converted to MeHg by bacteria, such as 

Desulfobacteraceae and Desulfovibrionaceae, that are present in wastewater (ACS, 2008). 

Researchers have detected concentrations of MeHg in dental wastewater that are orders of 

magnitude higher than background MeHg concentrations measured in environmental samples 
3-3 

(i.e., open oceans, lakes, and rainfall). Concentrations of MeHg in dental wastewater ranged 

from 0.90 to 26.77 mg/L, while concentrations in environmental samples ranged from 0.05 to 

10.0 ng/L (Stone et al., 2002). Researchers have concluded that sulfate-reducing bacteria are 

responsible for the presence of methylmercury in dental wastewater. However, it is not clear 

whether methylation occurs in the patient’s mouth or in the discharge stream (ACS, 2008). 

Although the MeHg concentrations are small compared to total mercury concentrations in dental 

wastewater, MeHg is particularly toxic to humans due to its ability to bioaccumulate in fish. 

When humans consume MeHg, it targets the nervous system and can hinder a person’s ability to 

walk, talk, see, and hear. Extreme cases of MeHg poisoning can result in coma or death (WI 

DNR, 1997). 

3.3 Dental Mercury Treatment at POTWs

 The composition of mercury discharged from dental offices is important to POTWs 

because it can affect the POTWs’ ability to remove mercury from influent wastewater. Solid 

mercury particles will likely settle out of solution and adsorb to the wastewater treatment sludge. 

However, dissolved mercury can pass through treatment operations and enter surface waters. 

EPA’s 50 POTW Study (EPA, 1982) estimates that POTWs can effectively remove 90 percent of 

total mercury (solid and dissolved) from wastewater. However, other studies conducted by 

Metropolitan Council Environmental Services (MCES) in 1995 and NACWA from 2002 through 

2006 have shown total mercury removals of 95 to 99 percent (Vandeven and McGinnis, 2005; 

AMSA, 2002; NACWA, 2007). 

 Mercury that partitions to wastewater sludge may be incinerated or disposed of in a 

landfill. Unbound mercury is highly volatile and can easily evaporate into the atmosphere. 

However, because the majority of dental mercury is bound to solid particles, it will not likely 

volatilize to the atmosphere unless the wastewater sludge is incinerated. Once in the atmosphere, 

mercury can be deposited into lakes and streams via precipitation (WI DNR, 1997). 
4-1 

4. CURRENT NATIONAL, STATE, AND LOCAL DENTAL MERCURY PROGRAMS

 This section discusses national, state, and local programs to reduce discharges of dental 

mercury. Currently, there are no federal regulatory requirements that specifically address 

discharges of dental mercury to wastewater. There are, however, federal requirements to control 

dangers of exposure to dental mercury. The ADA has recently adopted BMP guidance that 

includes the recommendation that dentists use amalgam separators. Requirements for controlling 

discharges of dental mercury to wastewater are set at the state and local level. Currently 11 states 

have established mandatory state-wide programs. EPA has also reviewed requirements for 19 

local mandatory programs spanning 6 states. The remainder of this section is organized into the 

following subsections: 

• Section 4.1 discusses national programs; 

• Section 4.2 summarizes state programs; 

• Section 4.3 summarizes local programs; and 

• Section 4.4 summarizes common elements found in state and local programs. 

4.1 National Dental Amalgam Requirements and Guidance

 This subsection summarizes national programs, including federal regulations and federal 

and non-federal guidance, for the use and disposal of dental amalgam. 

4.1.1 Federal Requirements and Guidance 

 Federal agencies that have established regulations for dental amalgam include the 

Occupational Safety and Health Administration (OSHA) and the Food and Drug Administration 

(FDA). Both federal regulations, however, focus on aspects of dental amalgam related to 

employee and consumer exposure and do not address discharges of dental amalgam to 

wastewater. This subsection also discusses EPA’s guidance and other efforts to reduce releases 

of mercury to the environment, including discharges of dental amalgam. EPA has not established 

national regulations for dental amalgam. 

Occupational Safety and Health Administration 

 OSHA’s authority regarding dental amalgam is limited to employee exposure resulting 

from handling or use of hazardous chemicals in the workplace. Dental amalgam is considered 

non-hazardous to consumers who receive dental restorations because the amalgam is considered 

benign once it is installed. However, workers handling amalgam have a greater potential for 

exposure than consumers, because dental workers handle liquid mercury while they prepare 

mercury amalgam restorations. For that reason, dental amalgam is classified as a hazardous 

chemical under OSHA’s Hazard Communication Standard. Workers who handle amalgam alloy 

are entitled to protection under this standard, including the receipt of training and hazard 

information. OSHA’s focus on dental amalgam is unrelated to the disposal of spent amalgam 

(OSHA, 1997). 

Food and Drug Administration 

 FDA regulates dental amalgam under the Federal Food, Drug, and Cosmetic Act 

(FFDCA). The FFDCA classifies dental mercury as a Class I medical device and amalgam alloy 
4-2 

as a Class II medical device (see Title 21, Code of Federal Regulations, sections 872.3700 and 

872.3050). Class I medical devices are subject to extensive safety regulations for use. Class II 

medical devices are subject to additional special controls for use (Anderson, 2007). FDA’s and 

CDC’s focus on dental amalgams is on the health risks to dentists, dental workers, and patients 

rather than the disposal of spent amalgam. According to FDA, dental amalgams contain mercury, 

which may have neurotoxic effects on the nervous systems of developing children and fetuses 

(FDA, 2008). 

U.S. Environmental Protection Agency 

 There are no federal effluent limitations guidelines for mercury discharges from dental 

offices and dental laboratories, but EPA and its regional offices work closely with states and 

communities to develop strategies for reducing effluent discharges of mercury, including 

discharges from dental facilities. For example, EPA’s Environmental Technology Verification 

Program studied amalgam separators to determine effectiveness (Grubbs, 2003). In addition, 

EPA regional offices participate in seminars and workshops with local organizations and other 

federal agencies to evaluate risks, develop recommendations, disseminate information, and 

communicate with the public regarding a wide range of mercury-associated issues. For example, 

EPA Region 4 participated in the Project Team on Consumption Advisories for Mercury in Gulf 

of Mexico Marine Fish. Also, EPA Regions 5 and 8 as well as EPA Headquarters have 

participated in the activities listed below to limit mercury discharge from dental facilities. 

• Region 5. EPA and Environment Canada, working through the Great Lakes Binational Toxics Strategy, created a Mercury Workgroup that promotes activities 

that will reduce mercury releases to the Great Lakes Basin. In addition to 

Environment Canada EPA’s Region 5, this workgroup includes representative 

states, environmental organizations, and the Council of Great Lakes Industries. 

The Workgroup’s review of mercury releases in the Great Lakes area has focused 

on air emissions. As a result, the Workgroup has not collected trend data on 

mercury releases to water. The Workgroup has reviewed information on BMPs 

and successful voluntary and regulatory approaches used in state and local 

programs, including dental amalgam reduction programs in King County, WA; 

Toronto, ON; Duluth, MN; and Cleveland, OH (EPA, 2003). In addition, the 

Workgroup has not quantified reductions in mercury use or reductions in 

discharge of dental amalgam to wastewater. 

• Region 8. EPA Region 8 developed a draft Mercury Control Strategy to help 

POTWs control mercury pollution problems from commercial, non-significant 

industrial users, including dental facilities. This draft Strategy includes detailed 

information on the development of BMPs, amalgam separators, and other removal 

and filtration devices, as well as other background information regarding dental 

amalgam control approaches (EPA, 2005). 

• EPA Headquarters (Office of Solid Waste)(OSW). OSW recommends four 

specific actions to manage amalgam waste at dental facilities. The first letters of 

each action form the acronym G.R.I.T.
4-3 

EPA Office of Solid Waste Recommendations for Dental Amalgam Waste Management 

G 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 

R 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. 

I 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. 

T Teach It Educate and train staff about the proper management of dental amalgam in the office. 

Source: David Carver, EPA/OSW 

 Disposal of mercury-containing waste is regulated under the Resource Conservation and 

Recovery Act (RCRA). A mercury-containing waste can be considered hazardous in two ways: 

1) as a listed waste; or 2) as a characteristic waste. There are some source-specific hazardous 

wastes that are listed due to mercury; however, dental amalgam wastes are not listed in 40 CFR 

Part 261 Subpart D. A waste can be defined as a characteristic hazardous waste if it exhibits the 

toxicity characteristics for mercury. This can occur when a sample of a waste contains enough 

mercury to exceed the regulatory threshold of 0.2 mg/l (or 0.2 ppm) when subjected to specific 

leach test known as the TCLP (Toxicity Characteristic Leaching Procedure; see 40 CFR 

§261.24). Persons who generate hazardous waste, such as a waste that exhibits the hazardous 

characteristics for mercury, are subject to specific requirements for the proper management and 

disposal of that waste. The federal RCRA regulations differ depending upon how much 

hazardous waste is generated per site per month. Most dentists generate less than 100 kg of nonacute hazardous waste per month and less than 1 kg of acute hazardous waste per month, and are 

therefore classified as “Conditionally Exempt Small Quantity Generators” (CESQGs). CESQGs 

are not subject to most of the RCRA hazardous waste requirements, provided the waste is 

otherwise managed properly. However, some states have additional requirements for CESQGs or 

do not exempt CESQGs from all requirements (HERCenter, 2008). 

4.1.2 American Dental Association Guidance 

 The most widely known national voluntary program is the “Best Management Practices 

for Amalgam Waste” developed and approved by the ADA Board of Trustees. This program was 

first published in January 2003 and updated in 2007 to include amalgam separators. All state and 

local voluntary programs are based on or derived from the guidance provided in the ADA BMPs. 

 ADA provides guidance documents for its members and the general public for the 

management and disposal of dental amalgam and amalgam waste. These include information 

regarding proper recycling of amalgam waste and practical guidelines for integrating BMPs into 

dental practices. ADA also provides advice for successful integration of BMPs into practices and 

offices, a directory of national dental waste recyclers, recommendations for safe preparation and 

placement of amalgam restorations, safety information for managing mercury spills, and advice 

on the purchase, installation, and operation of amalgam separators (ADA, 2007a). The ADAdefined BMPs are recognized as the industry standard. Table 4-1 lists the ADA BMPs for 

amalgam waste. 
4-4 

Table 4-1. ADA BMPs for Dental Amalgam 

Focus Best Management Practice 

General • Manage amalgam waste through recycling as much as possible. 

• Do not flush amalgam waste down the drain or toilet. 

• Use line cleaners that minimize the dissolution of amalgam. 

• Do not use bleach or chlorine-containing cleaners to flush wastewater lines. 

• Because amalgam waste may be mixed with body fluids or other potentially infectious material, 

use protective equipment such utility gloves, masks, and protective eyewear when handling it. 

• Check with city, county, or local waste authorities to get in touch with an amalgam waste recycler 

for any special requirements that may exist in the area for collecting, storing, and transporting 

amalgam waste. 

• Store amalgam waste in a covered plastic container labeled “Amalgam for Recycling” or as 

directed by the recycler. 

• Store different types of amalgam (e.g., contact and non-contact) in separate containers for 

recycling. 

Amalgam 

capsules 

• Do not use bulk elemental mercury, also referred to as liquid or raw mercury. 

• Recommend use of pre-capsulated alloys and stock a variety of capsule sizes since 1984. 

• Recycle used disposable amalgam capsules. 

• Do not put disposable amalgam capsules in biohazard containers, infectious waste containers (red 

bags), or regular garbage. 

Noncontact 

amalgam 

• Salvage, store, and recycle non-contact amalgam. 

• Do not put non-contact amalgam waste in biohazard containers, infectious waste containers (red 

bags), or regular garbage. 

• Place unused non-contact amalgam in a silver or gray storage container or a storage container with 

silver or gray label (keep containers sealed at all times). 

Contact 

amalgam 

• Salvage amalgam pieces from restorations after removal and recycle the amalgam waste. 

• Do not put contact amalgam waste in biohazard containers, infectious waste containers (red bags), 

or regular garbage. 

• Recycle teeth that contain amalgam restorations after confirming with the recycler that they will 

accept extracted teeth with amalgam restorations. 

• Do not dispose of extracted teeth that contain amalgam restorations in biohazard containers, 

infections waste containers (red bags), sharps containers, or regular garbage. 

• Do appropriately disinfect extracted teeth that contain amalgam restorations (e.g., 10 minutes in a 

1:10 bleach-to-water solution). 

• Place unused contact amalgam in a silver or gray storage container or a storage container with 

silver or gray label (keep containers sealed at all times). 

Chair-side 

traps 

• Use chair-side traps to retain amalgam and recycle the content. 

• Do not rinse chair side traps containing amalgam over drains or sinks. 

• Disposable traps from dental units dedicated strictly to hygiene may be placed in with the regular 

garbage. 

• Place disposable chair-side traps and the contents of reusable chair-side traps in a silver or gray 

storage container or a storage container with a silver or gray label (keep containers sealed at all 

times). 

Amalgam 

separators 

• Select an amalgam separator that complies with ISO 11143. 

• Follow the manufacturer’s recommendations for maintenance and recycling procedures. 

Other 

amalgam 

collection 

devices 

• Recycle contents retained by the vacuum pump filter, amalgam separator, or other amalgam 

collection device that may be used, if they contain amalgam. 

• Do not rinse vacuum pump filters containing amalgam, amalgam separator canisters, or other 

amalgam collection devices that may be used over drains or sinks. 

• Change the filter according to the manufacturer’s recommended schedule. 

• Place disposable vacuum pump filters and the contents of reusable vacuum pump filters in a silver 

or gray storage container or a storage container with silver or gray label (keep containers sealed at 

all times). 
4-5 

Table 4-1. ADA BMPs for Dental Amalgam 

Focus Best Management Practice 

Bulk 

elemental 

mercury 

• Recycle bulk mercury. 

• Check with licensed recycler to determine if they accept it. 

• Do not pour bulk mercury waste in the garbage, into a red bag, or down the drain. 

• Check with state regulatory agency and municipality to find out if a collection program is 

available. 

Source: ADA, 2007a.

4.2 State Dental Amalgam Requirements and Guidance

 This subsection describes state mandatory and voluntary programs for amalgam 

discharges from dental facilities. 

4.2.1 State Mandatory Programs 

 EPA identified the following 11 states as having mandatory program requirements for 

dental facilities: 

• Connecticut; 

• Louisiana; 

• Maine; 

• Massachusetts; 

• New Hampshire; 

• New Jersey; 

• New York; 

• Oregon; 

• Rhode Island; 

• Vermont; and 

• Washington. 

 States typically use the voluntary BMPs developed by ADA described above as the basis 

for their dental mercury discharge regulations. As a result, the state requirements share several 

common elements. Table 4-2 summarizes the elements of the various state regulations, including 

the types of requirements included and the methods used to demonstrate compliance with the 

regulations. Table 4-3 compares the state BMP requirements to the ADA BMPs. 

Table 4-2. Summary of Elements of State Requirements 

Element Examples from State Requirements 

Requirements • Install amalgam separators (CT, LA, MA, ME, NH, NJ, NY, OR, VT, WA, and only new 

offices in RI) 

• Follow state BMPs (CT, LA, MA, NH, NJ, NY, OR, RI, VT, WA). 

• Prohibits use of bulk mercury (LA, NJ, NY, OR). 

Amalgam Separator 

Technology 

Specifications 

• Meet ISO Standard 111143 (CT, ME, NH, NJ, NY, OR, RI, VT). 

• Operate at 95% efficiency (MA, ME, NY, VT) a. 

• Operate at 98% efficiency (MA if new, ME if after 3/20/03). 

• Operate at 99% efficiency (NY if new, RI). 
4-6 

Table 4-2. Summary of Elements of State Requirements 

Element Examples from State Requirements 

Operation 

specifications for 

amalgam separators 

• Must be operated at all times when dental procedures are performed (CT). 

• Must service every chair at practice where amalgam waste is generated (MA). 

• New offices must have separators installed prior to opening (OR). 

Method for 

demonstrating 

compliance 

• Submit separator certification to state environmental agency (CT, MA, ME, NJ). 

• Provide certification of compliance with BMPs (CT, MA, NH, NJ). 

• Maintain maintenance and servicing records and be able to provide upon request (CT, 

ME). 

• Provide written notice of method of disposing mercury removed by the separator (ME). 

Compliance tracking • DEP inspections (CT). 

• Web form for providing proof of compliance (RI). 

Sources: (CTDEP, 2006; MassDEP, 2007; ); (MEDEP, 2005); (MADEP, 2007); (NHDES, 2002); (NYDEC, 2007); 

(Oregon, 2007); (RIDEM, 2007); (VTDEC, 2006); (Walsh, 2007). 

a — In several states, if a facility has an amalgam separator in operation prior to implementation of the state law, 

then the state will allow the facility to continue operating that separator at its current efficiency. Only newly 

installed separators are required to meet operating efficiencies of 98 and 99 percent. 

In addition to the state requirements summarized in Table 4-2 and 4-3, New Mexico and 

Minnesota have proposed legislation for dental mercury controls and are awaiting approval. The 

bills would require all dental offices to install amalgam separators (Walsh, 2007). As of August 

2008, EPA has not found any information indicating that these bills have been enacted. 

 Bills for dental mercury controls were proposed but not passed in the following states: 

• Alabama. In 2004, the Alabama state legislature began debate on two bills 

designed to regulate the use of mercury in dental offices: HB 495, Mercury 

Amalgam Filling, and HB 665, Bill to Require Dentists to Provide Information 

about Mercury or Mercury Amalgam to Patients. It appears that both of these bills 

failed to clear the House and were tabled in the House Health Committee 

(ALISON, 2007). 

• Arkansas. The Mercury Poisoning Reduction Act of 2003 required the Arkansas 

Department of Environmental Quality to develop a plan for reducing mercury 

pollution from dental procedures and implement a mandatory program for dental 

offices by July 1, 2004 (Arkansas, 2003). However, EPA could not find 

information to determine if this Act had been either enacted or enforced. 

• California. In 2005, Assembly Bill 966, which would establish standards related 

to amalgam in dental and related services, passed the state Senate by a vote of 51 

to 28 but was vetoed by the governor’s office (California Legislative Counsel, 

2005). 
4-7 

Table 4-3. Best Management Practices by State 

Best Management Practice ADA CT LA MA NH NJ NRequirement/Guidance G R R R R R R Initial Use Use only pre-capsulated alloys and/or stock a variety of capsule sizes. Τ Τ Τ Τ Τ Τ Do not use bulk mercury. Τ Τ Τ Τ Recycling/Disposal Manage amalgam waste through recycling as much as possible. Τ Τ Τ Τ Τ Τ Τ Recycle used disposable amalgam capsules. Τ Τ Τ Τ Τ Do not flush amalgam waste down the drain or toilet. Τ Τ Τ Τ Τ Τ Salvage, store and recycle non-contact amalgam (scrap amalgam). Τ Τ Τ Τ Τ Τ Τ Salvage amalgam pieces from restorations after removal (contact amalgam) and recycle amalgam waste. 

Τ Τ Τ Τ Τ Τ Τ 

Recycle teeth that contain amalgam restorations. Τ Τ Τ Τ Τ Do not put used disposable amalgam capsules in biohazard containers, infectious waste containers (red bags) or regular garbage. 

Τ Τ Τ Τ Τ Τ 

Do not put non-contact amalgam waste in biohazard containers, infectious waste containers (red bags) or regular garbage. 

Τ Τ Τ Τ Τ Τ Τ 

Do not put contact amalgam waste in biohazard containers, infectious waste containers (red bags) or regular garbage. 

Τ Τ Τ Τ Τ Τ Τ 

Do not dispose of extracted teeth that contain amalgam restorations in biohazard containers, infectious waste containers (red bags), sharps containers or regular garbage. 

Τ Τ Τ Τ Τ Τ 

Chair-Side Traps Use chair-side traps to retain amalgam and recycle the content. Τ Τ Τ Τ Τ Τ Do not rinse chair-side traps containing amalgam over drains or sinks. Τ Τ Τ Τ Τ Τ Τ Where appropriate, disposable amalgam traps are preferable to reusable traps. Τ Τ Τ 
4-8 

Table 4-3. Best Management Practices by State 

Best Management Practice ADA CT LA MA NH NJ N

Requirement/Guidance G R R R R R R 

Vacuum Pumps Recycle contents retained by the vacuum pump filter or other amalgam collection device, if Τ Τ Τ Τ Τ Τ 

they contain amalgam. Do not rinse vacuum pump filters containing amalgam or other amalgam collection devices Τ Τ Τ Τ Τ Τ Τ 

over drains or sinks. Use line cleaners that minimize the dissolution of amalgam. Τ Τ Τ Τ 

Do not use bleach or chlorine-containing cleaners to flush wastewater lines. Τ Τ Τ Τ Τ Τ 

Amalgam Separators Install and use amalgam separators. Τ Τ Τ Τ Τ Τ Τ 

Other Any dental practice using mercury should maintain a mercury spill kit on site and train all Τ Τ Τ 

staff on mercury spill cleanup response procedure. Do not disinfect teeth or any item that contains amalgam using heat. Τ Τ Τ 

Sources: ADA, 2007a; CTDEP, 2006; MassDEP, 2007; NHDES, 2002; NJR, 2007; NYDEC, 2007; RIDEM, 2007; VTDEC, 2006; and G — Guidance. R — Requirement. 
4-9 

4.2.2 State Dental Amalgam Guidance 

 EPA has reviewed guidance from five states that provide voluntary guidelines and BMPs 

to dental offices: Florida, Idaho, Minnesota, Washington, and the District of Columbia. Table 4-4

summarizes the state BMPs and compares them to ADA’s BMPs. 

4.3 Local Dental Amalgam Requirements and Guidance

 This subsection summarizes mandatory and voluntary local programs for minimizing the 

discharge of dental mercury to wastewater. In addition, this subsection attempts to evaluate the 

effectives of local voluntary programs. EPA notes this subsection is not intended to be an 

exhaustive list of local programs. 

4.3.1 Local Dental Amalgam Requirements 

 EPA identified and reviewed mandatory program requirements for the following 9 

localities: 

• King County Wastewater Treatment Division (KCWTD), WA; 

• East Bay Municipal Utility District (EBMUD), Oakland, CA; 

• Palo Alto Regional Water Quality Control Plant (RWQCP), CA; 

• Northeast Ohio Regional Sewer District (NEORSD), Cleveland, OH; 

• Several Wisconsin sewerage districts: Madison, Milwaukee, Neenah-Menasha, 

Oshkosh, GrandChute and Menasha West, Wausau, Fond du Lac and Green BayDe Pere, Waukesha, Watertown, Beloit, and La Crosse (Behm, 2008); 

• Fort Collins and Boulder, CO; 

• San Francisco, CA; 

• Solon, OH; and 

• Narragansett Bay, RI. 

 Many elements included in the local requirements are similar to the state requirements 

described in Section 4.2.1. Table 4-5 summarizes the elements of the local requirements to 

control discharges of dental mercury. Table 4-6 compares the lists of local BMPs to ADA’s 

BMPs. 
4-10 

Table 4-4. Voluntary BMPs by State 

Best Management Practice ADA DC 

Initial Use Use only pre-capsulated alloys and/or stock a variety of capsule sizes. Τ Τ Do not use bulk mercury. Τ Τ Recycling/Disposal Manage amalgam waste through recycling as much as possible. Τ Τ Recycle used disposable amalgam capsules. Τ Τ Do not flush amalgam waste down the drain or toilet. Τ Τ Salvage, store, and recycle non-contact amalgam (scrap amalgam). Τ Τ Salvage amalgam pieces from restorations after removal (contact amalgam) and recycle amalgam waste. Τ Τ Recycle teeth that contain amalgam restorations. Τ Do not put used disposable amalgam capsules in biohazard containers, infectious waste containers (red bags), or regular garbage. 

Τ Τ 

Do not put non-contact amalgam waste in biohazard containers, infectious waste containers (red bags), or regular garbage. 

Τ Τ 

Do not put contact amalgam waste in biohazard containers, infectious waste containers (red bags), or regular garbage. Τ Τ Do not dispose of extracted teeth that contain amalgam restorations in biohazard containers, infectious waste containers 

(red bags), sharps containers, or regular garbage. 

Τ 

Chair-Side Traps Use chair-side traps to retain amalgam and recycle the content. Τ Τ Do not rinse chair-side traps containing amalgam over drains or sinks. Τ Τ Where appropriate, disposable amalgam traps are preferable to reusable traps. Τ Vacuum Pumps Recycle contents retained by the vacuum pump filter or other amalgam collection device, if they contain amalgam. Τ Τ Do not rinse vacuum pump filters containing amalgam or other amalgam collection devices over drains or sinks. Τ Τ Use line cleaners that minimize the dissolution of amalgam. Τ Τ Do not use bleach or chlorine-containing cleaners to flush wastewater lines. Τ Amalgam Separators Install and use amalgam separators. Τ 
4-11 

Table 4-4. Voluntary BMPs by State 

Best Management Practice ADA DC 

Other Any dental practice using mercury should maintain a mercury spill kit on site and train all staff on mercury spill 

cleanup response procedure. 

Τ 

Do not disinfect teeth or any item that contains amalgam using heat. 

Sources: ADA, 2007a; FLDEP, 2001; ISDA, 2008; MDA, 2003; WA Department of Ecology, 2006. a — According to sources at Quicksilver Caucus, the Washington program is currently a mandatory program. It is also listed in Section 
4-12 

Table 4-5. Summary of Elements of Local Requirements 

Element Examples from Local Requirements 

Requirements • Meet a mercury discharge limit of 0.2 ppm (King County) if a separator is not 

installed. 

• Install amalgam separators (East Bay, Palo Alto, Wisconsin, Fort Collins, San 

Francisco, Solon, Narragansett Bay). 

• Alternative to installing an amalgam separator: 

− Facility must pay a fee of $1,770/yr and be subject to inspections and testing 

(East Bay). 

− Facility must obtain a discharge permit and monitor wastewater (San 

Francisco). 

− Follow local BMPs (King County, Palo Alto, NE Ohio, Milwaukee, 

Narragansett Bay). 

Exemptions • Facilities that remove amalgam no more than three days per year (King County). 

• Certain specialty fields (King County). 

• Facilities that had installed separators prior to regulation (Palo Alto). 

Technology specifications • Meet ISO Standard 111143 (King County, Madison, East Bay). 

Method for demonstrating 

compliance 

• Provide certification for separator (East Bay, Palo Alto, Madison, Milwaukee). 

• Provide certification of compliance with BMPs (East Bay, Palo Alto, NE Ohio, 

Madison, Milwaukee). 

• Provide documentation of mercury waste hauling (East Bay, Palo Alto, NE 

Ohio). 

Compliance tracking • Enforcement protocol including notice of violation, compliance schedule, and 

penalties for noncompliance (King County). 

• Inspections performed by local POTW (East Bay, Palo Alto, Madison, 

Milwaukee). 

Sources: EBMUD, 2005; KCWTD, 2007; MMSD, 2008; NEORSD, 2007; Palo Alto, 2007; Walsh, 2007). 
4-13 

Table 4-6. Best Management Practices by Municipality 

Municipality 

Best Management Practice ADA 

East Bay, 

Oakland, 

CA 

King 

County, 

WA 

Milwaukee and 

Madison, WI a 

Narragan

Bay, R

Requirement/Guidance G R R R R 

Initial Use Use only pre-capsulated alloys and/or stock a variety of capsule sizes. Τ Τ Τ Τ Do not use bulk mercury. Τ Τ Recycling/Disposal Manage amalgam waste by recycling as much as possible. Τ Τ Τ Recycle used disposable amalgam capsules. Τ Τ Τ Do not flush amalgam waste down the drain or toilet. Τ Τ Τ Τ Τ Salvage, store, and recycle non-contact amalgam (scrap amalgam). Τ Τ Τ Τ Τ Salvage amalgam pieces from restorations after removal (contact amalgam) and recycle amalgam waste. 

Τ Τ Τ Τ Τ 

Recycle extracted teeth that contain amalgam restorations. Τ Τ ΤDo not put used disposable amalgam capsules in biohazard containers, infectious waste containers (red bags), or regular garbage. 

Τ Τ Τ Τ 

Do not put non-contact amalgam waste in biohazard containers, infectious waste containers (red bags), or regular garbage. 

Τ Τ Τ Τ 

Do not put contact amalgam waste in biohazard containers, infectious waste containers (red bags), or regular garbage. 

Τ Τ Τ Τ Τ 

Do not dispose of extracted teeth that contain amalgam restorations in biohazard containers, infectious waste containers (red bags), sharps containers, or regular garbage. 

Τ Τ Τ 

Chair-Side Traps Use chair-side traps to retain amalgam and recycle the content. Τ Τ Τ Τ Τ Do not rinse chair-side traps containing amalgam over drains or sinks. Τ Τ Τ Τ Τ Where appropriate, disposable amalgam traps are preferable to reusable traps. 

Τ Τ(G) 
4-14 

Table 4-6. Best Management Practices by Municipality 

Best Management Practice 

Municipality 

ADA 

East Bay, 

Oakland, 

CA 

King 

County, 

WA 

Milwaukee and 

Madison, WI a 

Narragan

Bay, R

Requirement/Guidance G R R R R 

Vacuum Pumps Recycle contents retained by the vacuum pump filter or amalgam collection device, if they contain amalgam. 

other Τ Τ Τ Τ Τ 

Do not rinse vacuum pump filters containing amalgam or other amalgam collection devices over drains or sinks. 

Τ Τ Τ Τ Τ 

Use line cleaners that minimize the dissolution of amalgam. Τ Τ Τ Do not use bleach or chlorine-containing cleaners to lines. 

flush wastewater Τ Τ Τ Τ 

Other Any dental practice using mercury should maintain a mercury spill kit on site and train all staff on mercury spill cleanup response procedure.

Τ Τ 

Install and use amalgam separators. T T T T T 

Sources: ADA, 2007a; EBMUD, 2005; KCWTD, 2007; NEORSD, 2007; Palo Alto, 2007; Uva, 2007; WDA, 2004. a — The Milwaukee and Madison programs reference BMPs developed by the Wisconsin Dental Association (WDA, 2004). G — Guidance. R — Requirement.
4-15 

4.3.2 Local Dental Amalgam Voluntary Programs 

 This section summarizes voluntary local programs that provided information to EPA on 

the participation rates for their programs. All of the programs involve outreach to dentists to 

educate them on BMPs and use of amalgam separators. The level of interaction between the 

program partners and local dentists varies greatly from program to program. Follow-up activities 

to verify participation include surveys, visits to dental offices, and contacting amalgam separator 

vendors and waste haulers for lists of customers. In some cases, the available information did not 

give EPA enough details to determine how the participation rates were verified. Table 4-7

summarizes the voluntary programs and presents the participation rates for the programs. This 

table also contains some state voluntary program participation rates for comparison purposes. 

4.3.2.1 Examples of Voluntary Programs with High Participation Rates 

 This subsection describes case studies of three voluntary programs that achieved 

participation rates greater than 90 percent or exceeded their goals for participation rates. It 

includes both local and state programs. 

 The Duluth program attributed its success to the following: 

• High level of cooperation from local dental societies; 

• One-on-one interaction with dentists; and 

• Providing financial incentives to dentists. 

 Kansas and Massachusetts each took a two-phase approach to their programs. Phase 1 

encouraged early installation of amalgam separators. Both states’ programs included specific 

goals and deadlines for participation. The second phase of the program implemented mandatory 

requirements for installation of amalgam separators at dental offices. Both states reported 

participation rates exceeding 50 percent for the voluntary phase. Based on the success of its 

voluntary program, Kansas decided not to implement mandatory requirements. Massachusetts 

decided to continue to implement mandatory requirements under phase 2; however, the state 

rewarded the dental offices that voluntarily installed amalgam separators during phase 1 by 

allowing them to operate amalgam separators at a lower efficiency than the separators required 

under phase 2. 

Duluth, Minnesota 

 In 1992, the Western Lake Superior Sanitary District (“WLSSD,” i.e., Duluth) and the 

Northeast District Dental Society formed a public-private partnership that taught dentists how to 

recycle amalgam waste, made presentations at local dental society meetings, and prepared and 

distributed written materials. As an incentive, the WLSSD purchased and installed separators at 

51 dental offices, but left the largest long-term cost (recycling the amalgam) to be paid by the 

dentists (Walsh, 2007). ADA attributed the success of the program to the leadership of the local 

dental society, peer-to-peer interaction with area dentists (including explaining the need to 

properly manage amalgam waste to prevent mercury from entering the environment and 

demonstrating the proper methods for doing so), financial incentives to install amalgam 

separators, and a discount waste disposal option through WLSSD’s “Clean Shop” Program. 

Currently, all 52 of the dental offices have installed amalgam separators. 
4-16 

Table 4-7. Summary of Voluntary Programs for Reducing Dental Amalgam Releases to Was

State (Jurisdiction) Date Description Participation Rate Verifi

California (Palo Alto, San Francisco, and Central Contra Costa) 

No 

information 

Voluntary installation of amalgam separators and implementation of BMPs. 

65% Survey c

districts 

Kansas (City of Wichita) 

April 2000 Developed a Mercury Code of Management Practices 

(CMP). Encouraged dentists to use technologies beyond chair side trap and vacuum filter (e.g. amalgam separator). Wichita planned to require mandatory installation of amalgam separators if participation in the voluntary program had been low, but found that a mandatory requirement was not necessary. 

98% (out of 200 offices) No infor

Massachusetts (MA Dental Society) 

2004 Goals were to have 50% of dentists install amalgam 

separators by January 2005, 90% participation by 2006, and 100% participation by 2007. MA later implemented mandatory requirements for amalgam separators. 

April 2005 — 75% No infor

Minnesota (MN Dental Association) 

2001 Voluntary installation of amalgam separators 85% of dentists have committed 

to installing separators. 

No infor

Minnesota (City of Duluth) 

2001-2003 Sanitation district purchased and installed amalgam 

separators in dental offices. Dentists are responsible for cost of recycling. The sanitation district and local dental society also provided education on how to recycle amalgam waste, trained dental offices, prepared written materials, and made presentations at dental society meetings. 

100% Sanitatio

oversaw amalgam 

Minnesota (Minneapolis, St. Paul) 

2003 Voluntary installation of amalgam separators. 

700 clinics participated in program. The voluntary program was accompanied by a threat of eventual regulation and an industrial permit requirement. 

99% of the clinics eligible for the program installed separators

No infor
4-17 

Table 4-7. Summary of Voluntary Programs for Reducing Dental Amalgam Releases to Was

State (Jurisdiction) Date Description Participation Rate Verifi

Missouri (Springfield)

2006 University of Missouri conducted a study to

determine whether voluntary BMPs could

significantly reduce mercury discharges from dental

offices. 

Offered a half-day training course on BMPs.Also sent outreach materials via mail to local 

members of the dental society. 

Collected wastewater samples to determine mercury 

reductions (see Section 5.2.2).

254 members in the local dental

society. 

54 (21%) local dentists attended

the half-day training session on

BMPs. 

76 (30%) dentists indicated that

they had implemented BMPs as 

a result of outreach. 

Very few dentists installed

amalgam separators. 

UM sent 

254 memsociety. 

Oregon (City of Corvallis) 

2003 Voluntary installation of amalgam separators and 

implementation of BMPs. 

Corvallis was awarded EPA’s 2006 National First 

Place Clean Water Act Recognition Award for Pretreatment Program Excellence. 

100%. No infor

Washington(WA Dental 

Association) 

August 

2003

Voluntary installation of amalgam separators and 

implementation of other BMPs. 

80% and anticipates an

additional 16%

No infor

Washington(Seattle and King

County) 

No

information

Significant outreach to dental offices on proper 

management of scrap amalgam, proper use of chairside trap and pump filter waste, and amalgam

separators. 

Participation rate was so low that King County 

decided to implement a mandatory program.

<50% managed scrap amalgam

properly. 

25% installed amalgam

separators. 

10% contracted with waste 

haulers. 

King CoMade un

dental of

Contacte

obtain li

custome

Contacte

away firdental of

Wisconsin (Madison) 

1997 Encouraged use of amalgam separators through 

outreach to dentists. 

Section 4.2.1 describes the mandatory program that

will be implemented in December 2008. 

23 of 103 dentists in the area 

(22%). 

Surveyed 

determinand/or re

many ha

separato

Sources: AMSA, 2002; MassDEP, 2007; MU Extension, 2007; Walsh, 2007; KCWTD, 2007; and MMSD, 2008. 
4-18 

Wichita, Kansas 

 In April 2000, the Wichita Department of Water and Sewer initiated a Mercury Code of 

Management Practices (CMP) for Wichita, Kansas. The CMP requires dental offices in Wichita, 

Kansas, to be equipped with devices to reduce the amount of amalgam discharged into the public 

waste streams. Phase 1 was an effort to encourage voluntary use of technologies beyond the 

chair-side trap and vacuum filter, e.g., a separator. Phase 2 of the program would have required 

mandatory separators if the voluntary effort was not successful. Phase 2 of the program was 

never implemented because 60 percent of dental community complied voluntarily. According to 

ADA, 98 percent of the 200 dental offices in the city complied with the Mercury CMP Program 

without a mandatory separator requirement (Walsh, 2007). 

Massachusetts 

 In 2004, the Massachusetts Department of Environmental Protection (MassDEP) worked 

with the Massachusetts Dental Society to establish a voluntary program for dentists to install 

amalgam separators. The program used a two-phase approach: 

• First, MassDEP implemented a voluntary program that encouraged dental offices 

to install and use amalgam separators. The program called for 50 percent 

participation by January 2005, 90 percent by January 2006, and 100 percent by 

January 2007. 

• Second, MassDEP implemented mandatory requirements, described in Section 

4.2.1, for operating amalgam separators, recycling amalgam waste, and certifying 

compliance. 

The voluntary portion of the program reported a 75 percent participation rate for the first year, 

exceeding MassDEP’s goals. In April 2006, MassDEP promulgated regulations mandating that 

most dental facilities install separators. Dentists who had complied with the voluntary program 

were rewarded with an exemption from the regulation (i.e. record keeping and reporting) until 

2007 or 2010, depending on how early the dentist complied. In addition, dentists who installed 

separators under the voluntary program were permitted to continue operating their separators at 

95 percent efficiency. The regulation required all newly installed of amalgam separators to 

operate at 98 percent efficiency (MassDEP, 2007). 

4.3.2.2 Examples of Voluntary Programs with Low Participation Rates 

 This section describes case studies for two voluntary programs that had participation rates 

below 50 percent. These programs, similar to the programs with high participation rates, 

conducted extensive outreach to local dentists to educate the dentists on BMPs and the use of 

amalgam separators. Despite this effort, one of the two programs discussed in this section 

decided to implement mandatory requirements for BMPs and amalgam separators due to the low 

level of participation in the voluntary program. 
4-19 

Seattle and King County 

 In 1995, the Seattle–King County Dental Society set up a standing committee to work 

with the King County government. These partners met several times a year and pursued a 

number of activities, including (EPA, 2004): 

• Developing a poster and a handbook for dentists; 

• Writing articles for a dental journal; 

• Mailing information to all members; 

• Co-sponsoring a free waste pick-up event; and 

• Presenting a “Green Dentistry” session at two Pacific Northwest Dental 

Conferences. 

 Other efforts undertaken independently by King County include: 

• Advertisements seeking to educate dentists; 

• Outreach to dental supply houses; 

• Outreach to vocational/technical programs for dental assistants; 

• Cash rebates for purchase of amalgam separators (up to $500); 

• Technical assistance visits to dental offices; and 

• Promotion of dentists as “EnviroStars.” 

 The Seattle-King County Dental Society won a regional environmental achievement 

award for its efforts to educate its members concerning mercury in dental wastewater. 

 During the fall of 1999 and spring of 2000, King County evaluated its voluntary dental 

program by conducting random visits to 212 dental offices and collecting data on the disposal of 

amalgam scrap, trap amalgam, pump filter sludge, and fixer. King County also contacted 

separator vendors to obtain lists of dental offices that had purchased and installed separators, and 

waste haulers and mail-away firms to obtain lists of dental offices with waste management 

contracts. 

 King County’s evaluation showed that the six-year voluntary program achieved the 

following results (EPA, 2004): 

• Less than half of dentists in the King County service area properly managed scrap 

amalgam. 

• Less than 25 percent of dentists properly managed chair-side trap and pump filter 

waste. 

• Only 25 dental offices installed amalgam separators (2.5 percent of those 

estimated to place and/or remove amalgam). 

• About 10 percent of dental offices contracted with waste haulers and/or mailaway firms. 
4-20 

• Hundreds of pounds of mercury from dental amalgams were still being disposed 

of annually to garbage, “red bags,” sewers, and “unknown” places. 

• The costs for King County’s voluntary program totaled over $250,000. During 

1995–2001, an estimated $4,500 was spent on advertisements, $24,000 on the 

production of a poster and handbook, $65,000 on equipment rebates, $63,500 on 

field visits, and $100,000 for staff time. 

 Due to the lack of immediate success of this voluntary program, King County began a 

mandatory program as of July 2003. The mandatory regulations are described in Section 4.3.1

(KCWTD, 2007). 

Springfield, Missouri 

 The Springfield program included extensive outreach to local dentists and was very 

successful in getting dentists to follow voluntary BMPs. However, the program was unsuccessful 

in getting dentists to install amalgam separators. The program staff concluded that amalgam 

separators were not installed because they are not required. 

 In 2006, the University of Missouri (MU Extension) began a study to determine whether 

dental offices could significantly reduce their mercury discharges though voluntary BMPs. 

Springfield was selected for the pilot study based on interest and commitment of staff resources 

from the Springfield Public Works Department and the Greater Springfield Dental Society 

(GSDS) (MU Extension, 2007). The discussion of this study presented in this section focuses on 

participation rates for the voluntary program. Effectiveness of BMPs on reducing mercury 

concentrations at POTWs is discussed in Section 5.2. 

 MU distributed a questionnaire to Springfield dentists in February 2006 to collect 

baseline data on amalgam use and management practices. The questionnaire was sent to 123 

dentists and there were 48 responses (39 percent). MU then offered area dentists a half-day 

training course on BMPs for dental amalgam. Eighty dentists and dental office staff representing 

54 local dental offices attended the training. Participants received a DVD, a wall poster with 

BMPs, a brochure of other available resources, and other written materials including: 

• Dental mercury hygiene recommendations; 

• ADA Guidelines on Amalgam Accumulations in Dental Office Plumbing; 

• Summary of Recent Study of Dental Amalgam in Wastewater; 

• The Missouri Department of Natural Resources’ determination of status and 

options for various types of dental waste; and 

• A list of amalgam recyclers. 

MU also sent training materials via mail to dentists who did not attend the course. 

 One year later, MU distributed a follow-up questionnaire to 254 members of the GSDS to 

measure any changes in management practices that resulted from MU’s education efforts. The 

response rate was 76 dental offices (30 percent). The comparison of responses on reported dental 

amalgam management practices before and after intervention showed that the BMP training and 

education efforts may have succeeded in changing some practices: 
4-21 

• Dental amalgam use decreased 5 percent from the previous year. 

• Improper disposal of capsules in regular waste decreased after the training and 

education, while the number of dentists reporting setting amalgam capsules aside 

for pickup by an amalgam recycler increased significantly. 

• The collection and recycling of scrap amalgam increased significantly after BMP 

training while the improper disposal decreased. 

• The amount of amalgam scrap disposed of as medical waste after the BMP 

training increased slightly. This finding may indicate a need for additional 

education for dental office staff and better labeling and instruction from medical 

waste management companies. 

• Use of chair-side traps increased from the year before; the practice of disposing of 

trap contents with regular waste decreased. 

• More of the dentists who use pump filters reported placing filter contents in a 

container with medical waste; also reported was a slight increase in placing filter 

contents in a container for pickup by an amalgam recycler. Fewer dentists 

reported that they place filter contents in regular office waste. 

• More dentists reported that they disinfected extracted teeth with amalgam 

restorations and set them aside for an amalgam recycler. 

• More dentists reported using an amalgam recycler and that their recycler also 

picks up medical waste. However, the majority of dentists reported that they were 

unable to recycle amalgam waste because they could not locate a recycler in their 

area, locate a recycler to pick up small quantities of dental amalgam waste, find a 

method for shipping waste, or afford recycling amalgam. 

 According to the results of the survey, the education efforts by MU were extremely 

successful in educating dentists on BMPs. However, the majority of the dentists in the 

Missouri/Springfield area did not use amalgam separators prior to outreach and did not install 

amalgam separators after MU conducted its outreach. MU concluded that very few dentists use 

amalgam separators because they are not required in Missouri or Springfield (MU Extension, 

2007). 

4.3.2.3 Summary 

 Participation rates in voluntary programs are highly variable, ranging from as high as 100 

percent of dentists in a community to as low as around 20 percent. Several programs that 

experienced low participation rates conducted extensive outreach and had frequent interaction 

with dentists. Therefore, the level of participation does not necessarily correspond to the level of 

outreach and education. 
4-22 

 The highest participation percentages were seen for voluntary programs that included the 

threat of a mandatory second phase. Examples of the mandatory second phase requirements 

include more stringent requirements for reporting or the requirement for higher amalgam 

separator efficiency standards. To avoid the more stringent mandatory requirements, dental 

facilities usually opted to comply with the voluntary requirements. Often, the mandatory second 

phase of the program was not ultimately implemented. Also, voluntary control programs that 

directly purchased amalgam separators for the dentists to install were very successful. 

 The level of interaction between the program partners and local dentists varies greatly 

from program to program. Follow-up activities to verify participation include conducting 

surveys, visiting dental offices, and contacting amalgam separator vendors and waste haulers for 

lists of customers. 

 According to an evaluation conducted by NACWA in 2002, participation rates in 

voluntary programs are highly variable, ranging from 100 percent to as low as 38 percent. 

NACWA also noted that during the first year of implementation regulatory programs will have 

higher participation rates than voluntary programs. However, over time (five to 10 years), 

participation rates for well-implemented voluntary programs will be similar to participation rates 

for mandatory programs (AMSA, 2002). 

4.4 Common Elements Found in State and Local Programs 

 This subsection attempts to summarize commonalities of state and local dental mercury 

programs discussed earlier in this section. These programs encourage the use of (1) BMPs at 

dental facilities to reduce the amount of mercury waste generated and (2) wastewater treatment 

technologies to capture and recycle the mercury that is present in discharges. 

Element 1 — Identify All Mercury Sources. 

 Several state and local programs attempt to characterize all sources of mercury in their 

influent. For example, East Bay implemented a program to sample wastewater at the POTW to 

establish baseline mercury concentrations in the influent, effluent, and biosolids. East Bay then 

used these data to calculate the percent contributions to the influent mercury load from 

residential and industrial sources (EBMUD, 2007). Similarly, King County conducted a dental 

office waste stream characterization study to determine baseline mercury discharges (King 

County, 1991). 

Table 4-8 lists potential non-dental mercury sources in POTW influent. 
4-23 

Table 4-8. Non-Dental Mercury Sources 

Commercial Activities Residential Sources

Hospitals 

Laboratories 

Universities 

Secondary schools 

Medical clinics 

Vehicle service facilities 

Industrial activities 

Human waste (amalgam) 

Human waste (dietary) 

Laundry graywater 

Household products 

Improper disposal of mercury thermometers 

Atmospheric deposition from coal-fired utilities 

Naturally occurring elemental mercury

Source: (EPA, 2005). 

Element 2 — Design the Program. 

 State and local programs develop criteria for participation, a list of BMPs for dental 

facilities, incentives for participation, and goals for the program. 

 The usual recommended criterion for including dental facilities in a mercury reduction 

program is whether the dental office conducts any placement or removal of amalgam fillings. 

Some programs exclude dental facilities using a de minimis amount of amalgam. The King 

County program exempts certain specialty fields and facilities that remove amalgam no more 

than three days per year (KCWTD, 2007). 

 The ISO standards for amalgam separators are generally employed (see Section 5.1.1). 

Requirements beyond the ISO standards require substantial effort. Programs in King County and 

Narragansett Bay have also contacted separator manufacturers and suppliers for their expertise in 

separator selection and the development of maintenance requirements for BMPs (Chaimberlain 

et al, 2005 and Uva, 2007). 

 During the design stage, state and local officials decide on the mechanism they would use 

to impose standards on the dental community. The size of the community has sometimes been a 

key factor for selecting the appropriate control mechanism. Larger communities sometimes 

found that a more formal program was necessary; smaller communities found that outreach and 

education was more manageable. 

 Some programs establish specific goals for the level of participation and a timeframe for 

implementing BMPs. For example, the Madison, WI program set goals of 100 percent 

compliance with BMPs and installation of amalgam separators by December 31, 2008 (MMSD, 

2008). 

 To provide incentives for participation, some programs issue awards recognizing positive 

action and subsidies for installing separators or recycling. Awards and subsidies successfully 

maintain rapport and speed progress. Mandatory programs also have required reporting and 

generally include penalties for facilities that do not comply with the requirements. 

 Finally, some programs have investigated opportunities to coordinate their amalgam 

work with other environmental or health programs. For example, amalgam management can be 

consolidated with work regarding lead foil, X-ray film development chemicals, radiation safety, 
4-24 

or medical waste (UW, 2008). The East Bay program included measures to control mercury from 

other industries in addition to dental facilities. (EBMUD, 2007). 

Element 3 — Outreach and Education

 A crucial element of any state or local program examined was effective outreach and 

education. Some examples are: 

• Identifying all dental facilities, using sources such as: local dental society 

membership lists, yellow pages, state licenses, and occupancy permits (UW, 

2008). 

• Issuing a survey or visiting conducting site visits to local dental offices to identify 

current practices (program baseline) and to increase awareness of the program. 

Prior to implementing its program, Palo Alto visited 43 percent of dental facilities 

in its service area and determined baseline BMP and amalgam separator use (Palo 

Alto, 2007). 

• Speaking to the local dental societies to introduce them to the program and to 

identify any work that has already been done to reduce mercury discharges. East 

Bay and Madison worked with their local dental societies to develop their dental 

programs (EBMUD, 2007 and MMSD, 2008). 

• Speaking to dental and technical schools about the program. 

• Maintaining a central database during the implementation of the program to track 

the program’s progress and document other changes to the local dentist 

population. The Madison Municipal Sewer District developed an in-house 

database to track to track the mercury program. The database is designed to 

manage contact data, facility identification and practices, survey data, and report 

generation (MMSD, 2008). 

Element 4 – Monitor Reductions/Measure Program Success

 For voluntary programs: One method for measuring the success of a voluntary program 

is looking at participation rates. To do this local programs have surveyed participants at local 

dental society meetings and mailed out surveys to measure participation rates. The University of 

Missouri (MU) conducted a study to evaluate the effectiveness of a voluntary program in 

Springfield, MO. MU issued a survey to dental society members to measure changes in BMP use 

among dentists in the area. This also had the added benefit of increasing awareness of the 

voluntary program (MU Extension, 2007). 

 For mandatory programs: Mandatory programs usually have more formal reporting and 

monitoring to ensure that requirements are being met. The following is a list of methods used by 

mandatory programs: 
4-25 

• Reporting wastewater monitoring, certification, and/or reporting. Dentists 

discharging to King County’s wastewater treatment division who elect not to 

install amalgam separators must demonstrate compliance with a 0.2 ppm mercury 

limit (KCWTD, 2007). 

• Reporting the dates, locations, and amount of mercury waste recycled. 

• Monitoring POTW influent/effluent/biosolids. East Bay monitors and analyzes 

mercury levels in its influent to measure the effectiveness of its program 

(EBMUD, 2007). King County uses biosolids monitoring data as an indicator of 

mercury levels in its treatment system (King County, 2008). 

• Conducting inspections of dental offices. King County conducts surprise 

inspections at dental facilities in its service area (KCWTD, 2007). 

• Requiring demonstration of amalgam separator installation. East Bay requires 

dentists to self certify installation of amalgam separators (EBMUD, 2007). 

• Requiring demonstration/certification of adherence to other BMPs. East Bay also 

requires dentists to self certify adherence to BMPs (EBMUD, 2007). 

• Collecting customer information from amalgam separator vendors (many 

manufacturers keep track for maintenance, parts replacement, and mercury 

recycling programs offered to their customers). King County contact amalgam 

separator vendors to obtain customer lists to evaluate participation rates for its 

voluntary program (KCWTD, 2007). 

Table 4-9 presents more specific examples of how mandatory programs have monitored 

compliance in state and local mercury control programs. 

Table 4-9. Compliance Requirements from State and Local Mandatory Programs 

Element Examples from State Programs Examples from Local Programs 

Submit separator certification to state 

environmental agency (CT, MA, ME, NJ). 

Provide certification for separator (East Bay, 

Palo Alto, Madison, Milwaukee). 

Provide certification of compliance with BMPs 

(CT, MA, NH, NJ).

Provide certification of compliance with BMPs 

(East Bay, Palo Alto, NE Ohio, Madison, 

Milwaukee). 

Maintain maintenance and servicing records 

and be able to provide upon request (CT, ME). 

Method for 

demonstrating 

compliance 

Provide written notice of method of disposing 

of mercury removed by the separator (ME). 

Provide documentation of mercury waste 

hauling (East Bay, Palo Alto, NE Ohio). 

DEP inspections (CT). Enforcement protocol including notice of 

violation, compliance schedule, and penalties 

for noncompliance (King County). 

Compliance 

tracking 

Web form for providing proof of compliance 

(RI). 

Inspections performed by local POTW (East 

Bay, Palo Alto, Madison, Milwaukee). 

Sources: EBMUD, 2005; KCWTD, 2007; MMSD, 2008; NEORSD, 2007; Palo Alto, 2007; Walsh, 2007). 
4-26 

 Finally, according to NACWA, sampling will be needed on a regular basis over a longer 

period of time to provide necessary trend information. This is because mercury concentrations 

will likely decrease slowly. For example, sewer cleaning may affect mercury concentrations, and 

there may be mercury deposits accumulated in the dental facility piping (NACWA, 2007a). 

Tracking the change in mercury concentration in the influent, effluent, and biosolids have been 

used to monitor mercury reductions and evaluate program success. East Bay determined that 

mercury levels in its influent decreased 78 percent from 1998 to 2006 and 96 percent of 

permitted dental facilities have installed separators (EBMUD, 2007). King County’s biosolids 

data showed a 50 percent decrease in mercury from 2000 to 2006 (King County, 2008). 
5-1 

5. EFFECTIVENESS AND COSTS OF DENTAL BMPS, INCLUDING AMALGAM SEPARATORS

 This section discusses the effectiveness and costs of reducing dental wastewater mercury 

discharges by implementing BMPs, including amalgam separators, at dental facilities. It also 

presents several case studies on influent and effluent POTW mercury concentrations following 

implementation of dental BMPs. 

 The remainder of this section is organized into the following subsections: 

• Section 5.1 discusses standards and treatment efficiencies for amalgam separators; 

• Section 5.2 presents case studies designed to demonstrate the impact of BMPs, 

including amalgam separators, on mercury levels in wastewater; and 

• Section 5.3 discusses costs of dental BMPs. 

5.1 Treatment Efficiencies and Standards for Amalgam Separators

 All BMPs, including chair-side traps and vacuum filters, can reduce amalgam discharges. 

The use of amalgam separators as a BMP is intended to further reduce amalgam discharges. The 

configuration, office size, and operation of the dental office can significantly affect the choice of 

separator. The choice can also be affected by the operation and maintenance requirements of the 

selected amalgam separator. The following section describes standards for amalgam separators 

and separator treatment efficiencies. 

5.1.1 Standards for Amalgam Separators 

 Two standards are used to evaluate treatment efficiencies of amalgam separators: 

• The International Organization for Standardization (ISO) Standard 11143 and 

• The U.S. Environmental Protection Agency’s Environmental Technologies 

Verification (ETV) program. 

ISO Standard 11143 

 The standard by which separators are most commonly evaluated is ISO Standard 11143 

for Amalgam Separators. This standard requires that an amalgam separator remove at least 95 

percent of amalgam particles by weight when subjected to a specific test method as specified in 

the Standard. The ISO test for removal efficiency uses 10.00 grams of amalgam particles that are 

composed of three portions of different sizes (ISO, 1999): 

• 60 percent of the particles are 3.15 millimeters or smaller and larger than 0.5 mm; 

• 10 percent of the particles are 0.5 mm or smaller and larger than 0.1 mm; and 

• 30 percent of the particles are 0.1 mm or smaller. 

 It is important to note that certification under this Standard is based not on total mercury 

concentration in effluent wastewater, but on particle removal. To test the efficiency of an 

amalgam separator, a slurry of water and amalgam is poured into the amalgam separator and 

effluent water is collected. This effluent wastewater is filtered through a series of pre-weighted 

filters, the filters are dried and weighed, and the final weight of the filters is then compared 
5-2 

against the original weight (Batchu et al., 2006). By this method, an ISO Standard 11143–

compliant amalgam separator will remove at least 95 percent, or 9.5 grams, of amalgam particles 

during laboratory testing. 

EPA/ETV Standard 

 The EPA/ETV program has developed a standard more rigorous than ISO 11143. The 

EPA/ETV standard, “Protocol for the Verification of Hg Amalgam Removal Technologies,” uses 

a concentration-based criterion and measures efficiency as a function of mercury concentration 

as opposed to particulate removal (NSF, 2001). EPA/ETV protocol recommends using Standard 

Methods 3500-Hg for sample collection, preservation, analysis, and storage. Standard Methods 

3500-Hg, is a cold vapor atomic absorption method for determining the concentration on 

mercury in potable water (APHA, 1998). The EPA/ETV standard protocol is not used nearly as 

widely as the ISO Standard likely due to a larger cost and time required for analyzing samples 

for the mercury content. See: http://www.epa.gov/etv/pubs/04_vp_mercury.pdf

5.1.2 Treatment Efficiencies 

 Studies have demonstrated the ability of amalgam separators to significantly reduce the 

amount of mercury amalgam in dental office wastewater. 

• A 1998 study tested three commercially available amalgam separators that used 

different separation technologies including gravity settling, settling/filtration, and 

mechanical centrifuge. The mercury removal efficiencies for the three 

technologies ranged from 95 to 99.9 percent. However, the study also noted that 

an effluent concentration of 0.2 parts per million could not be consistently met 

without chemical treatment (Boston University, 1998). 

• A 2001 study found that amalgam separators were able to remove 91 to 99 

percent of amalgam particles, with an average removal efficiency of 95 percent 

(MCES, 2001). 

• EPA Region 8 has reported that a properly installed amalgam separator will 

achieve removal efficiencies ranging from 95 to 99.99 percent of particulate 

mercury (EPA, 2005). 

 In dental offices, amalgam separators are commonly used in conjunction with chair-side 

traps and vacuum pump filters. Most chair-side traps can filter particles as small as 0.7 mm and 

vacuum filter traps can capture particles as small as 0.4 mm, resulting in a combined removal 

rate of 40 to 80 percent of amalgam particles. When chair-side traps and vacuum pump filters are 

used upstream of amalgam separators, the combined treatment system can achieve removal rates 

exceeding 99 percent (Fan et al., 2002). 

Table 5-1 provides a non-inclusive list of 28 commercially available amalgam separators, 

including manufacturer name, the type of particulate separation technologies used, and the 

amalgam removal efficiency based on ISO testing in a laboratory setting.2

 As illustrated, all 

 

2

 Mention of product and vendor names does not constitute an endorsement by EPA. 
5-3 

separators exceeded the ISO Standard of 95 percent efficiency, 25 separators exceeded 97 

percent efficiency, and 15 separators exceeded 99 percent efficiency of amalgam particle 

removal. The separators described in Table 5-1 achieved an average efficiency of 98.94 percent 

and a median efficiency of 98.7 percent. 

Table 5-1. Effectiveness of Amalgam Separators 

Model Manufacturer Treatment Technology 

Percentage of Amalgam 

Removal Efficiency d

A 1000 b Air Techniques Sedimentation 96.22% c

A 1300 a Air Techniques Sedimentation 99.27% 

Amalgam Boss a Hygenitek Sedimentation, filtration, ion 

exchange 

99.17% 

Amalgam Collector a R & D Services Sedimentation 99.40% 

ARU-10 e Hygenitek Sedimentation, filtration, ion 

Exchange 

99.99% 

Asdex b Avprox Filtration 99.23% c

Avprox AS-9 e American Dental 

Accessories 

Sedimentation, filtration 95%–99% 

BullfroHg b DRNA Dental Recycling Sedimentation, filtration 99.13% c

BullfroHg e Dental Recycling North 

America 

Sedimentation 98.3%–99.6% 

Durr 7800/7801 b Air Techniques Centrifugation 97.86% c

ECO II a Pure Water Development Sedimentation 97.05% 

Guardian Amalgam 

Collector e

Air Techniques Sedimentation >95% 

Hg Separator e SolmeteX Sedimentation, filtration, ion 

exchange 

>98% 

Hg5 a SolmeteX Sedimentation, filtration, ion 

exchange 

98.53% 

Hg5 with Effluent Flow 

Restrictor a

SolmeteX Sedimentation, filtration, ion 

exchange 

98.03% 

Hg5 HV a SolmeteX Sedimentation, filtration, ion 

exchange 

98.88% 

Hg10 b SolmeteX Sedimentation, filtration, ion 

exchange 

99.99% c

Merc II a Bio-Sym Medical Sedimentation, filtration, ion 

exchange 

98.06% 

MRU b DRNA Dental Recycling Sedimentation, filtration, ion 

exchange 

99.96% c

MRU 10c a DRNA/ADA Technologies Sedimentation, filtration, ion 

exchange 

99.97% 

MSS 1000 a Maximum Separation 

Systems 

Sedimentation, filtration 99.54% 

MSS 2000 b Maximum Separation 

Systems 

Sedimentation, filtration 99.3% c

Purevac Hg a Sultan Healthcare Sedimentation 99.91% 
5-4 

Table 5-1. Effectiveness of Amalgam Separators 

Model Manufacturer Treatment Technology

Percentage of Amalgam

Removal Efficiency d

Rasch 890-1000 a AB Dental Trends Sedimentation, filtration, ion

exchange 

98.94% c

Rasch 890-4000 b AB Dental Trends Sedimentation, filtration, ion

exchange 

99.92% c

Rasch 890-6000 a AB Dental Trends Sedimentation, filtration, ion

exchange 

98.31% c

REB e Rebec Simple Solutions Sedimentation 96.90% 

RME 2000 b Rebec Sedimentation 99.67% c

Average 98.7%

a — Results according to Batchu et al., 2006. 

b — Results according to Fan et al., 2002. 

c — Percentage of amalgam removal efficiency is calculated as the average of mean efficiency of empty separator 

and mean efficiency of full separator. 

d — This efficiency is based on the percentage of mercury in the form of dental amalgam removed by weight, as 

instructed in ISO Standard 11143. 

e — Results according to McManus and Fan, 2003. 

 As listed in Table 5-1, sedimentation, either alone or in conjunction with filtration and/or 

ion exchange, is used in the majority of amalgam separators. The high specific gravity of 

amalgam causes it to settle readily from suspension in water which allows the dental wastewater 

to be effectively treated by sedimentation (Fan et al., 2002). Although none of the separators 

listed in Table 5-1 used added chemicals, chemical and polymer additions can enhance 

sedimentation treatment and have demonstrated effectiveness in precipitating at least some 

portion of dissolved mercury out of dental wastewater. Some amalgam separator systems 

incorporate ion-exchange to remove dissolved mercury. 

5.2 Impacts of Dental BMPs, Including Amalgam Separators, on POTW Influent

 This subsection summarizes case studies demonstrating the impact of BMPs, including 

amalgam separators, on dental mercury discharges to POTWs. Most case studies show a 

decrease in the amount of mercury discharged to POTWs following installation of amalgam 

separators in dental offices. However, it is difficult to predict with any certainty the impact on 

POTW influent of the use of amalgam separators due, in part, to other mercury sources at 

POTWs. Also, other dental BMPS implemented at the same time as amalgam separators reduce 

mercury discharges to POTWs. 

5.2.1 Summary of Dental BMPs 

 Most state and local BMPs for dental facilities are based on the ADA BMPs developed in 

2003. Additionally, some municipalities require dental facilities to implement BMPs, while 

others have introduced voluntary BMP programs. Section 4 describes mandatory and voluntary 

programs. 

 To manage and recycle dental amalgam waste, ADA BMPs (ADA, 2007a) include the 

following: 
5-5 

• Using precapsulated alloys and stocking a variety of capsule sizes; 

• Recycling used disposable amalgam capsules; 

• Salvaging, storing and recycling non-contact amalgam; 

• Salvaging (contact) amalgam pieces from restorations after removal and recycling 

the amalgam waste; 

• Using chair-side traps, vacuum pump filters and amalgam separators to retain 

amalgam and recycle their contents; 

• Recycling teeth that contain amalgam restorations; 

• Managing amalgam waste through recycling as much as possible; and 

• Not using bleach or chlorine-containing cleaners to flush wastewater lines. 

 Using bleach or chlorine-containing cleaners can mobilize mercury from amalgam that 

has settled in plumbing fixtures and potentially cause the dissolution of mercury from amalgam 

waste (EPA, 2003 and Batchu et al, 2006a). Also, some BMPs encourage dentists to use 

approved suction line cleaners instead of oxidizing cleaners. Some BMPs recommend avoiding 

the use of heat to disinfect teeth or other items that contain amalgam to minimize air releases of 

mercury. 

5.2.2 Summary of Case Studies 

Table 5-2 summarizes dental BMP effectiveness on mercury discharged to POTWs, 

based on several studies. The City of Corvallis, OR, believes that the implementation of BMPs is 

highly effective in reducing the daily mass load of mercury in the influent to the Corvallis 

Wastewater Reclamation Plant (Lamperti, 2007). However, a study conducted by the National 

Association of Clean Water Agencies (NACWA) from 2003 to 2006 concluded that influent 

mercury loads at POTWs were highly variable. As a result, it was difficult to collect a 

representative sample. Although reductions were observed for some of the POTWs included in 

the study, NACWA concluded that the ability of POTW influent mercury loads to measure the 

impact of mercury control technologies at dental offices is limited (NACWA, 2007a). 

5.2.3 Considerations for Determining Impacts of BMPs on POTW Influent Mercury 

Levels 

 Although most of these studies show mercury reductions in POTW influent following the 

introduction of BMPs in dental offices, some studies show an increase in mercury 

concentrations. Thus, it is apparent that other factors can influence mercury levels and the 

measure of BMP effectiveness. As a result, there is uncertainty about the effectiveness of BMPs 

at reducing mercury at POTWs. Therefore, a POTW cannot predict with certainty that amalgam 

separators will decrease mercury concentrations in the influent wastewater without also 

exploring the other potential contributors (NACWA, 2007b). The following are examples of 

additional criteria that affected the mercury levels in the NACWA 2007 case studies. 

• Many programs are voluntary, making BMP participation rates hard to determine. 

• Dental offices are not the only source of mercury to POTWs. The next largest 

sources are domestic sources (human waste, household products, and laundry 

graywater) and hospitals (AMSA, 2002). 
5-6 

Table 5-2. Impact of BMPs on Mercury Discharged to POTW 

Percent of Dentists Using Amalgam 

Separators 

BMP Program Description Before Program After Program 

Percent Mercury Loa

Reduction 

California Dental Association 

Voluntary installation of amalgam separators. 

No information No information 78% of amalgam to POTW 

Corvallis, OR Voluntary installation of amalgam 

separators. 

No information No information 79% of POTW influent 

Springfield, MO BMP outreach program. No information No information 34% of POTW influent A Springfield, MO BMP outreach program No information No information 96% of POTW Influent B Madison, WI Voluntary installation of amalgam 

separators. 

No information 22% (as of 2005) No trend in POTW influen

EBMUD Required installation of amalgam 

separators. 

No information 96% No trend in POTW influen

Wichita, KS Voluntary installation of amalgam 

separators. 

60% 99% No trend in POTW influen

Milwaukee, WI Required installation of amalgam 

separators. 

No information No information Decrease in POTW influen

Duluth, MN St. Louis River Beneficiary Group 

provided a grant to purchase amalgam separators for all offices. 

No information 100% Decrease in POTW sludge 

Palo Alto, CA Required installation of amalgam 

separators. 

No information 96% No trend in POTW influen

Narragansett Bay, RI 

Voluntary installation of amalgam separators. 

No information No information No trend in POTW influen

MCES — Metropolitan Wastewater Treatment Plant 

Voluntary installation of amalgam separators. 

No information No information 50.6% of POTW influent 

MCES — Hastings Wastewater Treatment Plant 

Community-wide study. MCES established a baseline, installed the amalgam separators at dental offices, conducted sampling, and then removed the amalgam separators. 

0% 100% 

(6 facilities total) 

44% of POTW influent 
5-7 

Table 5-2. Impact of BMPs on Mercury Discharged to POTW 

Percent of Dentists Using Amalgam 

Separators Percent Mercury Loa

BMP Program Description Reduction 

Before Program After Program 

MCES — Cottage Community-wide study. MCES 0% 87.5% 29% of POTW influent Grove Wastewater established a baseline, installed the (7 out of 8 facilities) Treatment Plant amalgam separators at dental offices, 

conducted sampling, and then removed the amalgam separators. 

King County, WA Voluntary installation of amalgam No information 95% 50% of POTW biosolids 

separators and mandatory (concentration-basis) implementation of BMPs. 

POTW “A” Required facilities to either install 0% 100% No trend in POTW influen

amalgam separators or demonstrate compliance with a mercury limit of 0.005 ppm. 

POTW “B” Mandatory BMP program began in 5% 9% (out of 219 56.4% of POTW influent 

2002. Installation of amalgam separators facilities) was not required. 

POTW “C” BMP program began in 2002. Some 6% 6% (out of 18 43% of POTW influent 

BMPs were mandatory. Installation of facilities) amalgam separators was voluntary. 

POTWs “D” and Program required implementation of 0.6% 38% (total number of 60.5% of influent to POTW 

“E” BMPs by 2004 and installation of facilities unknown) “D”; 

amalgam separators by 2008. 22.0% of influent to POTW 

POTW “F” Voluntary amalgam separator program 0% 20% (total number of 38.0% of POTW influent 

began in 1997. facilities unknown) 

POTW “G” Voluntary installation of amalgam 44% 100% (100 facilities 90% increase to POTW in

separators. total) 

POTW “H” Voluntary amalgam separator program 60% 98% (out of ~200 No trend in POTW influen

began in 2002. facilities) 

POTW “I” Mandatory amalgam separator program 94% 98% (total number of 27.5% of POTW influent 

began in 2001. facilities unknown) 

POTWs “J” and Mandatory program required dentists to 94% 98% (total number of 8.9% increase to POTW “J

“K” meet a limit of 0.2 mg/L by July 2003. facilities unknown) 44.1% reduction to POTW 
5-8 

Table 5-2. Impact of BMPs on Mercury Discharged to POTW 

BMP Program Description 

Percent of Dentists Using Amalgam 

Separators Percent Mercury Loa

Reduction 

Before Program After Program 

POTW “L” POTW recommends installation of No information 11% (total number of 50.6% of POTW influent 

amalgam separators to dentists. facilities unknown) 

a — Northwest Treatment Plant. b — Southwest Treatment Plant. 
5-9 

• The time required to flush accumulated amalgam particles from the collection 

system is not known. 

• The time needed for mercury reductions at POTWs to be measurable after BMPs 

are implemented is not known. 

5.3 Costs of Dental BMPs

 The cost of a BMP program includes costs to state and local agencies to implement the 

program and costs to individual dental facilities to participate. The costs to local agencies include 

development of the program and costs for outreach to dentists. Depending on the program, the 

costs to individual dental offices will generally encompass purchasing, installing, and 

maintaining an amalgam separator; recycling the collected amalgam; and other costs, such as 

time spent educating their employees. The California Dental Association indicates that “the 

numerical cost of BMP implementation is low” (Condrin, 2004), and according to Bates, BMPs 

would cost approximately $300 per facility per year if implemented in New Jersey (Bates, 2006). 

5.3.1 BMP Program Costs to State and Local Agencies 

Table 5-3 shows the costs of several pollution prevention program elements estimated by 

AMSA and the Oregon Association of Clean Water Agencies (ACWA). These cost estimates are 

based on the cost of pollution prevention programs and the cost to develop pollution prevention 

programs in the past. All the pollution prevention/voluntary programs presented in Table 5-3

addressed only dentists. 

Table 5-3. Cost of BMP Program to State and Local Agencies 

Program Description 

Total Cost 

($2008) 

Number of 

Participants Source 

San Francisco, CA Brochure/fact sheets + distribution $80,600 900 AMSA, 2002

San Francisco, CA Site visits $16,100 35 visits AMSA, 2002

Palo Alto, CA Brochure/fact sheets + distribution $16,100 500 AMSA, 2002

Palo Alto, CA Outreach/advisory group $13,400 500 AMSA, 2002

Western Lake Superior 

District, MN 

Outreach $40,300 100 AMSA, 2002

Salem, OR Staff labor $8,330 109 ACWA, 2007

Salem, OR Inspection or other form of contact $4,880 109 ACWA, 2007

Oregon State All costs in 2004 $3,950 53 ACWA, 2007

Oregon State All costs in 2005 $1,420 26 ACWA, 2007

Oregon State All costs in 2006 $6,380 36 ACWA, 2007

5.3.2 Costs to Facilities 

 The major costs to dental offices for implementing mandatory or voluntary BMP 

programs are the costs to purchase and maintain an amalgam separator and the costs to collect 

and recycle amalgam waste. This subsection describes these costs. 
5-10 

Amalgam Separator Costs 

 Most BMP programs recommend, if not require, dental offices to install amalgam 

separators. Dentists have three options for obtaining amalgam separators: 

• Purchase the unit and maintain it themselves; 

• Purchase the unit and contract a company to maintain it; or 

• Lease the unit, with maintenance service inclusive in the fee. 

 Amalgam separator life-cycle costs can include (PACE, 2007): 

• Purchase or lease cost; 

• Installation cost; 

• Additional equipment costs; 

• Maintenance costs; 

• Replacement cost; 

• Shipping costs; and 

• Recycling costs. 

 Manufacturer suggested retail prices (MSRP) range from $215 to $7,450 (depending on 

the size of the dental office), and certain models can be installed and operated under lease 

arrangements for $39 to $100 per month. Table 5-4 provides a summary of costs of 

commercially available amalgam separator systems (non-inclusive), including specific operating 

and maintenance costs for each model in 2008 dollars.3 

To verify the manufacturer estimates in Table 5-4, Table 5-5 presents amalgam separator 

purchase, installation, operation, and maintenance costs from information provided in other 

studies. 

 

3

 Mention of product and vendor names does not constitute an endorsement by EPA. 
5-11 

Table 5-4. Cost of Purchasing, Operating and Maintaining Amalgam Separators ($2008

Model Manufacturer MSRP Maintenance Replacement Parts Recycling?

F

A1000 Air Techniques $1,010 Replace collecting 

containers every 6 months 

Filter: $672 Not 

included 

A110 Air Techniques $2,020 Replace collecting 

containers every 6 months 

Replacement kit: $1,010 Included 

A1200 Air Techniques $2,020 Replace collecting 

containers every 6 months 

Replacement kit: $1,010 Included 

A1300 Air Techniques $4,030 Replace collecting 

containers every 6 months 

Replacement kit: $1,010 Included 

A1400 Air Techniques $4,340 Replace collecting 

containers every 6 months 

Replacement kit: $1,010 Included 

Amalgam Collector 

R & D Services $470–$1,680 Conduct weekly 

maintenance and decant treated wastewater Replace unit every 9 to 12 months Sludge removal every 2 to 5 years 

Unknown Not 

included 

$4

ARU-10 Hygenitek $671–$928 

Lease: $52/mo 

Replace canister every 6 months Replace sedimentation tank every 6–24 months 

Filter canister: $133–$202 Sedimentation tank: $79–$101 

Included $9

Avprox Asdex American 

Dental Accessories 

$289 Replace canister every 4–6 

weeks 

Canister: $47 Not 

included 

$

Avprox AS-9 American 

Dental Accessories 

$309 Replace filter every 3–8 

months 

Filter: $106 Not 

included 

$

BullfroHg Dental 

Recycling North America 

Purchase: $934 

Lease: $134/mo 

(2-year minimum)

Replace separator annually Unknown 

Included in lease 

$605 / year 

Catch Hg 400 Series 

Rebec $1,320 Annual recycling required Annual recycling: $531 Included 
5-12 

Table 5-4. Cost of Purchasing, Operating and Maintaining Amalgam Separators ($2008

F

Model Manufacturer MSRP Maintenance Replacement Parts Recycling? 

Catch Hg 1000 Rebec $2,550–$4,030 Annual recycling required Annual recycling: $531– Included $3,

Series $665 Durr System Air Techniques $5,380 Replace cassette once per Cassette: $128 Included 7800/7801 year ECO II Pure Water Purchase: $739 Apply recommended Cleanser: $101 Included 

Development Lease: $73/mo cleanser daily Replacements are included 

Replace separator annually under the lease 

Guardian Air Techniques $2,020–$4,380 Replace collection Replacement kit: $1010 Included $2,Amalgam container every 6 to 12 Collector months Hg5 Solmtex $934 Replace cartridge every 6 Resin cartridge: $202–$370 Not $1,

(1–10 chairs) months Filter: $101–$202 included 

Hg10 Solmtex $10,010 Replace cartridge every 6 Resin cartridge: $202–$370 Not 

(>10 chairs) months Filter: $101–$202 included 

Merc II Bio-Sym $1,200–$1,740 Replace unit annually Replacement unit installation Included $1,

Medical and disposal: $665 

MSS Model Maximum $1300–$1,880 Replace settling tank Settling tank: $222 Not $1,

1000 Separation annually Tank recycling: $249 included 

Systems Cleanser: $101 

MSS Model Maximum $4,030 Replace settling tank Settling tank: $222 Not 

2000 Separation annually Tank recycling: $249 included 

Systems Cleanser: $101 

REB 1000 Rebec Simple $2,550 Annual recycling required Replacement parts: $531 Included 

Solutions 

REB 5000 Rebec Simple $2,550 Annual recycling required Replacement parts: $531 Included 

Solutions 

REB 7000 Rebec Simple $2,550 Annual recycling required Replacement parts: $665 Included 

Solutions 

REB 9000 Rebec Simple $4,030 Annual recycling required Replacement parts: $531 Included 

Solutions 

Rasch 890- AB Dental $1,600 Replace canister every 12– Canister: $801 Included 

1000 Trends 18 months 
5-13 

Table 5-4. Cost of Purchasing, Operating and Maintaining Amalgam Separators ($2008

Model Manufacturer MSRP Maintenance Replacement Parts Recycling?

F

Rasch 890-4000 

AB Dental Trends 

$2,220 Replace canister every 12–

18 months 

Canister: $1,010 Included 

Rasch 890-6000 

AB Dental Trends 

$895 Replace canister every 12–

18 months 

Canister: $801 Included 

Average $2,320 

Table adapted from EBMUD, 2002 and 2004; McManus and Fan, 2003. Journal of the American Dental Association. Purchasing, InstaDental Amalgam Separators. Volume 134, August 2003 (pp. 1054-1059). 
5-14 

Table 5-5. Estimated Purchase, Installation, and O&M Costs of Amalgam Separator 

($2008) 

Purchase Cost Installation Cost O&M Cost 

Source Low High Low High Low High 

Metropolitan Council Environmental Services 

and the Minnesota Dental Association (MCES, 

2001) 

$221 $4,840 $415 $691 

Association of Metropolitan Sewerage Agencies 

(AMSA, 2002) 

$134 $4,030 $565 $3,230 

King County (WA) Department of Natural 

Resources and Parks (King County, 2005) 

$171 $2,280 $228 $571 $228 $799 

Palo Alto (CA) Regional Water Quality Control 

Plant (RWQCP), Amalgam Recovery Program 

(Palo Alto, 2007) 

$181 $2,410 $60 $1,204 $301 $722 

Binational Toxics Strategy Mercury Workgroup, 

Great Lakes National Program Office, U.S. EPA 

(EPA, 2003) 

$393 $3,930 $262 $262 

Vandeven and McGinnis a (Vandeven and 

McGinnis, 2004) 

$1,200 $2,410 

Bates (Bates, 2006) $748 $1,070 

U.S. EPA (EPA, 2003) $98 $983 

Journal of the California Dental Association 

(Condrin, 2004) 

$361 $602 

 (Behm, 2008) $600 $1,500 $200 $600 

Average b $283 $3,170 $188 $659 $388 $1,160 

a — The range of prices includes both the cost of purchase and installation. 

b — Does not include Vandeven and McGinnis costs. 

 A key component in amalgam separator installation costs is labor for plumbers, pipe 

fitters, and steamfitters. According to the 2006 Occupational Employment and Wage survey and 

consistent with a MCES study, the mean hourly wage for plumbers, pipe fitters, and steamfitters 

is $22.03, not including benefits (BLS, 2006a). Based on the studies described above and the 

average MSRP for separator models included in Table 5-4 ($1,580), a conservative estimate for 

the cost of purchasing and installing an amalgam separator is about $2,000. Table 5-7 below 

shows that the average MSRP and annual O&M costs provided by manufacturers in Table 5-4

that fall within the average high- and low-cost range determined in Table 5-5 from nine regional 

studies. 

Table 5-6. Summary of Cost Estimates 

Type of Cost Cost ($2008) 

Average cost of purchase (Table 5-4) $2,320 

Average cost of purchase range (Table 5-5) $283–$3,170 

Average annual cost of O&M (Table 5-4) $657 

Average annual cost of O&M range (Table 5-5) $388–$1,160 
5-15 

 Cost of amalgam separators can vary, but are relative to the size of the dental operation. 

Table 5-7 lists prices based on information gathered by Partners for a Clean Environment 

(PACE) from manufacturers in September 2005. The number of amalgam separators to be 

installed depends on the number of chairs in an office and the amalgam separator model. The 

wastewater flow rate determines how often filters and traps need to be cleaned/replaced (Walsh, 

2007). The costs for small dental offices are close to itemized and annual costs estimated in 

Tables 5-4 and 5-5. 

Table 5-7. Estimated Annual Cost for Amalgam Separators by Size of Dental Office 

($2008) 

Small (1–4 Chairs) Medium (5–12 Chairs) Large (+12 Chairs) 

Purchase $228–$1,370 $760–$2,510 $2,850–$10,000 

Installation $114–$228 $143–$297 $228–$1,140 

Maintenance $0–$228 $0–$228 $0–$228 

Replacement $57–$856 $86–$856 $571–$2,400 

Estimated annual cost $211–$1,073 $293–$1,110 $1,990–$4,630 

Source: Walsh, 2007. 

5.3.3 Amalgam Recycling 

 For 11 of the 15 separators examined (see Table 5-4), costs included recycling services 

and the replacement of used amalgam canisters. This recycling service included either: 

• The recycler picking up amalgam waste at dental offices or 

• The recycler providing packaging material, shipping labels and shipping 

manifests to the dentist so they can ship the collected amalgam to the recycler 

Annual service and maintenance costs—including recycling—range from $95 to $750 per year. 

The ADA estimated a conservative (low) cost of using a recycling service to be $450 per year 

(Walsh, 2007). EPA estimates recycling costs are less than $600 per year (Singer, 2007b). 
6-1

6. DENTAL MERCURY PASS-THROUGH ANALYSIS

 This section describes EPA’s analysis of the potential for dental mercury discharges to 

pass through POTWs. EPA determined the potential for pass-through by comparing the 

percentage of mercury removed by well-operated POTWs achieving secondary treatment 

(“baseline discharges”) with the percentage of pollutant removed assuming100 percent 

participation in an amalgam separator program. EPA typically determines pass-through by 

comparing the baseline discharges with the limits for Best Available Technology Economically 

Achievable (BAT) for the category. EPA has not set national categorical regulations for the 

health services industry, however, so BAT limits do not exist for comparison. The following 

subsections describe EPA’s assumptions and calculations for this analysis: 

• Section 6.1 presents the number of dentists using amalgam; 

• Section 6.2 presents calculations for mercury discharges from amalgam 

restorations and amalgam removals; 

• Section 6.3 summarizes the baseline mercury discharge to POTWs; 

• Section 6.4 presents estimates of potential reductions from the installation of 

amalgam separators; 

• Section 6.5 summarizes the annualized costs for amalgam separators; and 

• Section 6.6 summarizes the results for the assumed participation rates and 

associated costs. 

6.1 Number of Dentists

 This subsection summarizes the data and assumptions that EPA used to estimate the 

number of dentists in the United States who potentially install or remove amalgam restorations. 

A 2007 ADA survey reported a total of 163,181 active dentists in the United States in 2004 

(ADA, 2007b). Although only a portion of these dentists install amalgam restorations (e.g., a 

2005 study by VanDeven and McGuiness estimates that 75 percent of general dentists install 

amalgam restorations), all dentists have the potential to remove old amalgam when installing 

new, non-mercury restorations. Therefore EPA assumed that all active general dentists and 

specialists who work in fields that use amalgam may remove old amalgam fillings. Similarly, it 

was assumed that all U.S. dental offices (122,918) would be subject to mandatory amalgam 

separator installation programs because all offices have the potential to discharge mercury from 

amalgam removals even if they do not install amalgam restorations. 

 Calculations that use assumptions based on the number of dentists or dental offices 

include the mass of mercury discharged from amalgam removals and the number of facilities 

using chair-side traps, vacuum pump filters, and amalgam separators. The mass of mercury 

discharged from amalgam removals (see Table 6-3) is based on the total number of dentists. For 

this calculation, EPA used the estimated number of specialists in fields that use amalgam 

(11,353) and the number of general dentists (129,745) from Table 6-1. To calculate the baseline 

use of chair-side traps, vacuum pump filters, and amalgam separators (see Table 6-4), EPA used 

assumptions based on the number of dental offices. For these calculations, EPA used the total 

number of dental offices (122,918) from Table 6-1. 
6-2

Table 6-1. Estimate of Total Number of Dentists 

Description Value Type Calculation Source/Notes 

Total number of active dentists 162,181 Data None ADA, 2007b 

Number of general dentists 129,745 Estimation 80% of total dentists ADA, 2007b 

Number of specialists 32,436 Estimation 20% of total dentists ADA, 2007b 

Number of specialists in fields 

that use amalgam 

11,353 Estimation 35% of specialists that work in 

fields that use amalgam 

Vandevin & 

McGuiness, 2005 

Total number of dental facilities 122,918 Data None ADA, 2007b 

6.2 Mercury Discharge from Amalgam Restorations and Amalgam Removal 

 This subsection summarizes the calculations used to determine the tons of mercury 

discharged from amalgam restorations and amalgam removals. Table 6-2 shows detailed 

calculations used in this analysis to determine the total amount of mercury discharged to POTWs 

from amalgam restorations. 

Table 6-2. Determining the Total Mercury Discharge from Amalgam Restorations 

Description Value Type Calculation Source 

Number of total restorations 

performed in US in 1999 

71,000,000 Data None Vandeven and 

McGinnis, 2005 

Mercury content of amalgam 

capsule 

450 mg Data None Vandeven and 

McGinnis, 2005 

Amount of mercury used for 

restoration 

340 mg Data None Vandeven and 

McGinnis, 2005 

Amount of mercury disposed 

of as non-contact scrap 

amalgam 

110 mg Data None Vandeven and 

McGinnis, 2005 

Amount of mercury used per 

restoration that is discharged 

to wastewater 

31 mg Estimation 9% of the amount of mercury used 

for restorations 

Vandeven and 

McGinnis, 2005 

Total amount of mercury 

discharged to wastewater 

from restorations 

2.40 tons Result Product of number of restorations 

performed (71,000,000) and 

amount of mercury used per 

restoration that is discharged to 

wastewater (31 mg) 

 

Table 6-3 shows detailed calculations used to determine the total amount of mercury 

discharged to POTWs from amalgam removals. 

Table 6-3. Determining the Total Mercury Discharge from Amalgam Removals 

Description Value Type Calculation Source 

Total number of removals 

per general dentist per year 

710 Data None Vandeven and McGinnis, 

2005 

Total number of removals 

per specialist per year 

440 Data None Vandeven and McGinnis, 

2005 
6-3

Table 6-3. Determining the Total Mercury Discharge from Amalgam Removals 

Description Value Type Calculation Source 

Total number of removals by 

general dentists 

92,118,808 Estimation Product of removals by 

general dentists (710) 

and number of general 

dentists (129,745) 

See Table 6-1

Total number of removals by 

specialists 

4,995,175 Estimation Product of removals by 

specialist (440) and 

number of specialists 

who work in fields that 

use amalgam (11,353) 

See Table 6-1

Total number of removals 97,113,983 Estimation Sum the number of 

removals by performed 

by general dentists and 

specialists 

 

Mercury content of amalgam 

removed 

300 mg Data None Vandeven and McGinnis, 

2005 a

Amount of mercury per 

removal that is discharged to 

wastewater 

270 mg Assumption 90% of mercury content 

of amalgam removed 

Vandeven and McGinnis, 

2005 

Total amount of mercury 

discharges to wastewater 

from amalgam removals 

27.4 tons Result Product of amount of 

mercury per removal 

that is discharged to 

wastewater (270 mg) 

and total number of 

removals (97,113,983) 

 

a — Accounts for decay and deterioration of amalgam filling over time. 

 According to Tables 6-2 and 6-3, EPA estimates the total mercury mass present in 

untreated dental wastewater due to both installing and removing amalgam restorations to be 31.3 

tons. This is the mass prior to any removals from chair-side traps, vacuum filters, or amalgam 

separators. 

6.3 Determining Baseline Mercury Discharge to POTWs

 This subsection summarizes the calculations used to determine the baseline mercury 

discharged to POTWs. The mercury discharge is calculated for each group of dental facilities 

using the same type of amalgam treatment system. For estimation of baseline loads, EPA 

assumed that some dental facilities already had treatment in place. EPA assumed that 100 

percent of dental offices had chair-side traps and that 80 percent of facilities also used vacuum 

filters. These assumptions are consistent with ADA’s analysis (Vandeven and McGinnis, 2005). 

To estimate the number of dental facilities with amalgam separators installed, EPA used the 

following assumptions using 2005 census data for the number of dental facilities by state 

(presented in Table 6-8 located at the end of this section): 

• 100 percent of facilities in each state have the potential to remove amalgam 

fillings from their patients. 
6-4

• If the state had a mandatory program that required the use of amalgam separators, 

then 100 percent of the dental offices used amalgam separators. 

• If the state had no program, then EPA assumed that 20 percent of the dental 

offices used amalgam separators. (EPA assumed 20 percent to account for dentists 

that might have installed an amalgam separator on their own and to account for 

local amalgam separator programs.) 

Table 6-4 describes in detail the calculation used to determine the total baseline mercury 

discharged to POTWs. 

Table 6-4. Determining the Baseline Mercury Discharge to Wastewater 

Description Value Type Calculation Source 

Number of facilities using 

only chair-side traps 

24,584 Assumption 20% of all dental facilities 

use only chair-side traps 

Vandeven and McGinnis, 

2005 

Number of facilities using 

chair-side traps and vacuum 

pump filters 

49,167 Assumption 40% of dental facilities use 

only chair-side traps and 

vacuum pump filters 

Vandeven and McGinnis, 

2005 

Number of facilities using 

chair-side traps, vacuum 

pump filters, and amalgam 

separators 

49,167 Assumption 40% of dental facilities use 

amalgam separators, vacuum 

pump filters, and chair-side 

traps 

See Table 6-8

Removal efficiency of chairside trap 0.680 Data None Vandeven and McGinnis, 

2005 

Removal efficiency of chairside trap + vacuum pump 

filter 

0.810 Data None Vandeven and McGinnis, 

2005 

Removal efficiency of chairside trap, vacuum pump 

filter, and amalgam separator 

0.991 Data None Median of amalgam 

separator efficiencies in 

Table 5-1 of Section 5.1

Mercury discharges from 

facilities using only chairside traps 

2.00 tons Estimation Product of the ratio of the 

number of facilities using 

only chair-side traps to the 

total number of facilities; the 

total estimated mercury 

discharge; and 68% removal 

efficiency of chair-side traps 

See Table 6-1 and Section 

6.2

Mercury discharges from 

facilities using only chairside traps and vacuum pump 

filters 

2.38 tons Estimation Product of the ratio of the 

number of facilities using 

chair-side traps and vacuum 

pumps to the total number of 

facilities; the total estimated 

mercury discharge; and 81% 

removal efficiency for the 

vacuum pump and chair-side 

traps 

See Table 6-1 and Section 

6.2
6-5

Table 6-4. Determining the Baseline Mercury Discharge to Wastewater 

Description Value Type Calculation Source 

Mercury discharges from 

facilities using chair-side 

traps, vacuum pump filters, 

and amalgam separators 

0.11 tons Estimation Product of the ratio of the 

number of facilities using 

amalgam separators, chairside traps and vacuum pumps 

to the total number of 

facilities; the total estimated 

mercury discharge; and 

99.1% removal efficiency for 

the combined treatment 

system 

See Table 6-1 and Section 

6.2

Total baseline mercury 

discharges to POTWs 

4.50 tons Result Sum of mercury discharge 

from facilities using only 

chair-side traps (2.00 tons); 

using chair-side traps and 

vacuum pump filter (2.38 

tons); and using chair-side 

traps, vacuum pump filters, 

and amalgam separators 

(0.11 tons) 

 

POTW removal efficiency 0.90 Data None Median POTW removal 

efficiency (EPA, 1982) 

Total baseline mercury 

discharges to receiving 

streams 

0.45 tons Result Amount of mercury 

discharged to receiving 

stream after POTW 

removal (4.50(1-0.9)) 

 

6.4 Potential Reduction from Installation of Amalgam Separators

This subsection presents EPA’s estimates of the potential mercury reductions due to new 

installations of amalgam separators. Table 6-5 shows the potential mercury reductions in 

discharge to POTWs as a result of a mandatory amalgam separator installation programs. This 

assumes that 100 percent of dental facilities will install amalgam separators. 

Table 6-5. Potential Reductions of Mercury to POTWs from Mandatory Installation of 

Amalgam Separators 

Description Value Type Calculation Source 

Total baseline mercury 

discharges to POTWs for 

facilities that do not operate 

amalgam separators 

4.38 tons Estimation Sum of discharges from facilities 

that use only chair-side traps (2.00 

tons) and vacuum pump filters 

(2.38 tons) 

See Table 6-4

Number of additional 

facilities that would install 

99.2 percent efficiency 

amalgam separators 

73,751 Estimation Sum of facilities that use only 

chair-side traps (24,584) and 

vacuum pump filters (49,167) 

See Table 6-4
6-6

Table 6-5. Potential Reductions of Mercury to POTWs from Mandatory Installation of 

Amalgam Separators 

Description Value Type Calculation Source 

Mercury discharges after 

installation of amalgam

separators at these facilities 

0.175 tons Estimation Product of the ratio of the number 

of facilities that would install 

amalgam separators to the total 

number of facilities; the total 

estimated mercury discharge; and

99.1% removal efficiency for the 

combined treatment system. 

See Table 6-1, 

Table 6-4, and 

Section 6.2

Reduction of mercury

discharges to POTWs 

4.21 tons Estimation Difference of baseline mercury 

discharges to POTWs for facilities 

that do not operate amalgam

separators (4.38 tons) and mercury

discharges after installation of 

amalgam separators (0.175 tons) 

 

Total mercury discharges to 

POTWs following

mandatory installation of 

Amalgam Separators 

0.29 tons Result Sum of mercury dischargers

after installation of amalgam 

separators (0.175 tons) and from

current facilities using chairside traps, vacuum pump filters, 

and amalgam separators (0.11

tons). 

See Table 6-4

POTW removal efficiency 0.90 Estimation Median POTW

removal efficiency

(EPA, 1982)

Total discharges to 

receiving stream 

0.029 tons Result Amount of mercury discharged 

to receiving stream after POTW 

removal (0.29(1-0.9)) 

 

Total reductions to

receiving stream 

0.421 tons Result Difference of total baseline 

mercury discharges to receiving 

stream (0.45 tons) and total 

discharges to receiving stream 

(0.029 tons) 

See Table 6-4

6.5 Annualized Costs for Amalgam Separators

Table 6-6 summarizes the average annualized cost of installing an amalgam separators 

based on calculations for the first year of purchase and all subsequent years for the lifetime of the 

separator. 
6-7

Table 6-6. Calculation of Cost 

Description Cost ($2008) Reference 

First year cost of amalgam separator 

unit 

$2,550.00 Average cost from Table 5-4

Annual cost for amalgam separator 

after first year 

$657.00 Average cost from Table 5-4

Lifetime of separator (years) 10 Vandeven and McGinnis, 2005 

Interest rate 0.07 

Capital recovery factor 0.14 

Annualized capital investment cost $363.06 

Total annualized cost $1,020.06 

6.6 Summary and Costs

 This subsection summarizes the potential reductions in mercury discharges expressed in 

both tons and toxic-weighted pound equivalents (TWPE). Table 6-7 presents these reductions 

and the costs of installing amalgam separators to demonstrate the economic impact to the dental 

industry. 

Table 6-7. Summary of Calculations 

Calculation Baseline 

100% Amalgam Separator 

Installation 

Tons of mercury discharged to POTW from dental 

facilities 

4.50 0.29 

Tons of mercury discharged to surface water a 0.45 0.029 

Mercury TWPE discharged to surface water (lb-eq) 105,000 6,790 

Reduction of mercury discharges to POTWs (tons) 0 4.21 

Reduction of mercury discharges to receiving 

stream (tons) 

0 0.421 

Reduction of mercury TWPE to receiving stream 

(lb-eq) b

0 98,200 

Number of facilities to install amalgam separators c 0 73,800 

Cost to industry ($2008) (assumes 1 separator per 

facility) 

$0.00 $75,200,000 

a — EPA assumed a POTW removal efficiency of 90 percent. 

b — Toxic weighting factor for Hg is 117. 

c — For baseline, EPA assumed that 122,918 dental facilities in the U.S. c (see Section 6.1) and that 40 percent of 

these dental facilities use amalgam separators (see Section 6.3). 

Table 6-8 presents the 2005 census data used to determine the percent of dental facilities 

that currently have amalgam separators installed in the United States. 
6-8

Table 6-8. Number of Dental Facilities and Amalgam Separator Use by State 

State 

NAICS 621210 Dental 

Offices 

Assumed Percent 

Operating Amalgam 

Separators a

Estimated Number 

Operating Amalgam 

Separators 

Alabama 478 0.2 96 

Alaska 560 0.2 112 

Arizona 263 0.2 53 

Arkansas 3,050 0.2 610 

California 412 0.2 82 

Colorado 1,732 0.2 346 

Connecticut b 9,017 1 9,017 

Delaware 4,546 0.2 909 

District of Columbia 5,258 0.2 1,052 

Florida 4,357 0.2 871 

Georgia 2,334 0.2 467 

Hawaii 5,639 0.2 1,128 

Idaho 4,353 0.2 871 

Illinois 2,023 0.2 405 

Indiana 1,922 0.2 384 

Iowa 1,077 0.2 215 

Kansas 2,153 0.2 431 

Kentucky 259 0.2 52 

Louisiana 267 0.2 53 

Maine b 790 1 790 

Maryland 1,016 0.2 203 

Massachusetts b 243 1 243 

Michigan 2,483 0.2 497 

Minnesota c 315 0.85 268 

Mississippi 2,845 0.2 569 

Missouri 573 0.2 115 

Montana 2,720 0.2 544 

Nebraska 1,368 0.2 274 

Nevada 3,024 0.2 605 

New Hampshire b 6,733 1 6,733 

New Jersey b 1,586 1 1,586 

New Mexico 2,110 0.2 422 

New York b 1,417 1 1,417 

North Carolina 846 0.2 169 

North Dakota 933 0.2 187 

Ohio 1,527 0.2 305 

Oklahoma 1,325 0.2 265 

Oregon b 7,597 1 7,597 

Pennsylvania 414 0.2 83 

Rhode Island b 656 1 656 

South Carolina 222 0.2 44 
6-9

Table 6-8. Number of Dental Facilities and Amalgam Separator Use by State 

State 

NAICS 621210 Dental 

Offices 

Assumed Percent 

Operating Amalgam 

Separators a

Estimated Number 

Operating Amalgam 

Separators 

South Dakota 2,366 0.2 473 

Tennessee 593 0.2 119 

Texas 2,209 0.2 442 

Utah 1,418 0.2 284 

Vermont b 883 1 883 

Virginia 3,183 0.2 637 

Washington c 1,825 0.8 1,460 

West Virginia 19,005 0.2 3,801 

Wisconsin 307 0.2 61

Wyoming 686 0.2 137 

Total U.S. 122,918 49,021 

Percent of Total Dental Offices 40%

Source: Census, 2005. 

a — Assumes 100 percent compliance with mandatory programs, uses Table 4-7 in Section 4 for state voluntary 

program participation rates, and assumes 20% for states with no information. 

b — State requires amalgam separators. 

c — State has voluntary program for installation of amalgam separators with information on participation rates in 

Section 4. 
7-1

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