EPA-821-R-08-014
&EPA
United
Environmental
Agency
Health Services Industry Detailed Study
Dental Amalgam
August 2008
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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
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CONTENTS (Continued)
Page
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
11
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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
iii
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LIST OF TABLES (Continued)
Page
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
IV
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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 (WIDNR, 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
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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-defmed 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 mercury-
free fillings and improved overall dental health, the use of mercury in dentistry is decreasing in
the U.S.
ES-2
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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:
1-1
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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.
1-2
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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
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
NAICS 339116 Dental Laboratories
107
16
153
58
1,011
153
80
NAICS 621210 Dental Offices
1,417
307
2,209
933
19,005
2,366
1,732
2-1
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Table 2-1. Number of Establishments by State (2005)
State
Delaware
District of Columbia
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Nebraska
Nevada
New Hampshire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
NAICS 339116 Dental Laboratories
8
2
566
247
38
59
318
139
69
55
73
97
27
108
113
208
134
47
144
38
49
73
32
219
38
469
228
10
232
71
143
216
30
63
18
128
377
117
18
177
276
NAICS 621210 Dental Offices
243
315
6,733
3,024
686
656
5,639
2,334
1,077
1,016
1,586
1,527
478
2,483
3,050
4,353
1,922
846
2,153
414
790
883
560
4,546
593
9,017
2,720
259
4,357
1,325
1,825
5258
412
1,368
267
2,110
7,597
1,418
263
2,845
3,183
2-2
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Table 2-1. Number of Establishments by State (2005)
State
West Virginia
Wisconsin
Wyoming
Total U.S.
NAICS 339116 Dental Laboratories
26
135
12
7,225
NAICS 621210 Dental Offices
573
2,023
222
122,918
Source: Census, 2005a.
Table 2-2. Number of Dental Laboratories and Offices
NAICS Code
3391 16: Dental
Laboratories
621210: Offices of
Dentists
SIC Code
8072: Dental
Laboratories
8021: Offices and
Clinics of Dentists
Number of Facilities
in 1997
7,609
114,178
Number of Facilities
in 2002
7,096
118,305
Number of Facilities
in 2005
7,225
122,918
Sources: Johnston, 2005; Census, 2005a andb.
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
3391 16: Dental
Laboratories
621210: Dental
Offices
Number of
Establishments
7,096
118,305
Revenues
($1,000)
3,361,996
71,102,922
Paid Employees
49,467
743,628
Average Revenue
($1,000)
$473.79
$601.01
Employees per
Establishment
6.97
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).
2-3
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Table 2-4. Number of Single-Unit and Multi-Unit Firms (2005)
NAICS
339116: Dental Laboratories
621210: Dental Offices
Number of Firms
6,925
113,302
Number of
Establishments
7,096
118,305
Single-Unit Firms
110,841
Multi-Unit Firms
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
3391 16: Dental
Laboratories
621210: Dental
Offices
Size Standard
500 employees
$6.5 million
Total
7,096
118,305
Definitely
Small
7,086
107,258
Possibly
Small
9,805
Best Estimate
Small
7,086
116,843
% Small
99.9%
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).l 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)
2-4
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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 vOl). 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 mPCSLoads2004_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).
2-5
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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)
NAICS
3391 16: Dental
Laboratories
621210: Dental
Offices
Revenues (SMillions)
All
1.7
0.9
$0-$1
0.8
$l-$3
2.7
0.9
$3-$5
0.7
$5-$10
0.9
$10-$25
0.8
>$25
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 sub category.)
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.
2-6
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Table 2-7. 2006 Profit Before Taxes (%)
NAICS
3391 16: Dental
Laboratories
621210: Dental
Offices
Revenues (SMillions)
All
5.0
10.4
$0-$1
11.7
$l-$3
5.8
10.4
$3-$5
7.1
$5-$10
7.7
$10-$25
6.3
>$25
6.2
Source: RMA, 2007.
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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.
3-1
-------
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., AgsSn, Ag2Hg3, SngHg) 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
Total mercury
MeHg (monomethyl mercury)
HgO (elemental mercury)
Hg+2 (ionic mercury)
HgO (elemental mercury bound to
amalgam particulate)
Measured Concentration
21.438 milligrams/liter (ppm)
277.74 nanograms/liter (ppt)
24.06 micrograms/liter (ppb)
54 micrograms/liter (ppb)
21.360 milligrams/liter (ppm)
Percent of Total Mercury
100.0%
0.001296%
0.112231%
0.251889%
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
-------
(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).
3-3
-------
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
-------
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 Bi-
national 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.
4-2
-------
EPA Office of Solid Waste Recommendations for Dental Amalgam Waste Management
G
R
I
T
Grey Bag It
Recycle It
Install It
Teach 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
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.
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.
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/1 (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 non-
acute 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 (FIERCenter, 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 ADA-
defined BMPs are recognized as the industry standard. Table 4-1 lists the ADA BMPs for
amalgam waste.
4-3
-------
Table 4-1. ADA BMPs for Dental Amalgam
Focus
Best Management Practice
Amalgam
capsules
Contact
amalgam
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.
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.
Non- Salvage, store, and recycle non-contact amalgam.
contact Do not put non-contact amalgam waste in biohazard containers, infectious waste containers (red
amalgam 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).
Chair-side
traps
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).
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 Select an amalgam separator that complies with ISO 11143.
separators Follow the manufacturer's recommendations for maintenance and recycling procedures.
Other Recycle contents retained by the vacuum pump filter, amalgam separator, or other amalgam
amalgam collection device that may be used, if they contain amalgam.
collection Do not rinse vacuum pump filters containing amalgam, amalgam separator canisters, or other
devices 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).
4-4
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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, 2007'a.
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
Requirements
Amalgam Separator
Technology
Specifications
Examples from State 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).
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).
4-5
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Table 4-2. Summary of Elements of State Requirements
Element
Operation
specifications for
amalgam separators
Method for
demonstrating
compliance
Compliance tracking
Examples from State Requirements
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).
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).
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).
4-6
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Table 4-3. Best Management Practices by State
Best Management Practice
Requirement/Guidance
ADA
G
CT
R
LA
R
MA
R
NH
R
NJ
R
NY
R
OR
R
RI
R
VT
R
WA
R
Initial Use
Use only pre-capsulated alloys and/or stock a variety of capsule sizes.
Do not use bulk mercury.
T
T
T
T
T
T
T
T
T
T
T
T
Recycling/Disposal
Manage amalgam waste through recycling as much as possible.
Recycle used disposable amalgam capsules.
Do not flush amalgam waste down the drain or toilet.
Salvage, store and recycle non-contact amalgam (scrap amalgam).
Salvage amalgam pieces from restorations after removal (contact amalgam) and recycle
amalgam waste.
Recycle teeth that contain amalgam restorations.
Do not put used disposable amalgam capsules in biohazard containers, infectious waste
containers (red bags) or regular garbage.
Do not put non-contact amalgam waste in biohazard containers, infectious waste containers
(red bags) or regular garbage.
Do not put contact amalgam waste in biohazard containers, infectious waste containers (red
bags) or regular garbage.
Do not dispose of extracted teeth that contain amalgam restorations in biohazard containers,
infectious waste containers (red bags), sharps containers or regular garbage.
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
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.
Where appropriate, disposable amalgam traps are preferable to reusable traps.
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
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Table 4-3. Best Management Practices by State
Best Management Practice
Requirement/Guidance
ADA
G
CT
R
LA
R
MA
R
NH
R
NJ
R
NY
R
OR
R
RI
R
VT
R
WA
R
Vacuum Pumps
Recycle contents retained by the vacuum pump filter or other amalgam collection device, if
they contain amalgam.
Do not rinse vacuum pump filters containing amalgam or other amalgam collection devices
over drains or sinks.
Use line cleaners that minimize the dissolution of amalgam.
Do not use bleach or chlorine-containing cleaners to flush wastewater lines.
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
Amalgam Separators
Install and use amalgam separators.
T
T
T
T
T
T
T
T
T
T
T
Other
Any dental practice using mercury should maintain a mercury spill kit on site and train all
staff on mercury spill cleanup response procedure.
Do not disinfect teeth or any item that contains amalgam using heat.
T
T
T
T
T
T
T
T
T
oo
Sources: ADA, 2007a; CTDEP, 2006; MassDEP, 2007; NHDES, 2002; NJR, 2007; NYDEC, 2007; RIDEM, 2007; VTDEC, 2006; and Lamperti, 2007.
G Guidance.
R Requirement.
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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 Bay-
De 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.
4-9
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Table 4-4. Voluntary BMPs by State
Best Management Practice
ADA
DC
FL
ID
MN
WAa
Initial Use
Use only pre-capsulated alloys and/or stock a variety of capsule sizes.
Do not use bulk mercury.
T
T
T
T
T
T
T
T
Recycling/Disposal
Manage amalgam waste through recycling as much as possible.
Recycle used disposable amalgam capsules.
Do not flush amalgam waste down the drain or toilet.
Salvage, store, and recycle non-contact amalgam (scrap amalgam).
Salvage amalgam pieces from restorations after removal (contact amalgam) and recycle amalgam waste.
Recycle teeth that contain amalgam restorations.
Do not put used disposable amalgam capsules in biohazard containers, infectious waste containers (red bags), or regular
garbage.
Do not put non-contact amalgam waste in biohazard containers, infectious waste containers (red bags), or regular
garbage.
Do not put contact amalgam waste in biohazard containers, infectious waste containers (red bags), or regular garbage.
Do not dispose of extracted teeth that contain amalgam restorations in biohazard containers, infectious waste containers
(red bags), sharps containers, or regular garbage.
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
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.
Where appropriate, disposable amalgam traps are preferable to reusable traps.
T
T
T
T
T
T
T
T
T
T
T
T
T
T
Vacuum Pumps
Recycle contents retained by the vacuum pump filter or other amalgam collection device, if they contain amalgam.
Do not rinse vacuum pump filters containing amalgam or other amalgam collection devices over drains or sinks.
Use line cleaners that minimize the dissolution of amalgam.
Do not use bleach or chlorine-containing cleaners to flush wastewater lines.
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
Amalgam Separators
Install and use amalgam separators.
T
T
T
T
-------
Table 4-4. Voluntary BMPs by State
Best Management Practice
ADA
DC
FL
ID
MN
WAa
Other
Any dental practice using mercury should maintain a mercury spill kit on site and train all staff on mercury spill
cleanup response procedure.
Do not disinfect teeth or any item that contains amalgam using heat.
T
T
T
Sources: ADA, 2007a; FLDEP, 2001; ISO A, 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 4.2.1 of this report.
-------
Table 4-5. Summary of Elements of Local Requirements
Element
Requirements
Exemptions
Technology specifications
Method for demonstrating
compliance
Compliance tracking
Examples from Local 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 $l,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).
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).
Meet ISO Standard 1 1 1 143 (King County, Madison, East Bay).
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).
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).
4-12
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Table 4-6. Best Management Practices by Municipality
Best Management Practice
Requirement/Guidance
Municipality
ADA
G
East Bay,
Oakland,
CA
R
King
County,
WA
R
Milwaukee and
Madison, WI a
R
Narragansett
Bay,RI
R
NE Ohio,
Cleveland,
OH
R
Palo
Alto,
CA
R
Initial Use
Use only pre-capsulated alloys and/or stock a variety of capsule sizes.
Do not use bulk mercury.
T
T
T
T
T
T
T
T
T
T
Recycling/Disposal
Manage amalgam waste by recycling as much as possible.
Recycle used disposable amalgam capsules.
Do not flush amalgam waste down the drain or toilet.
Salvage, store, and recycle non-contact amalgam (scrap amalgam).
Salvage amalgam pieces from restorations after removal (contact
amalgam) and recycle amalgam waste.
Recycle extracted teeth that contain amalgam restorations.
Do not put used disposable amalgam capsules in biohazard
containers, infectious waste containers (red bags), or regular garbage.
Do not put non-contact amalgam waste in biohazard containers,
infectious waste containers (red bags), or regular garbage.
Do not put contact amalgam waste in biohazard containers, infectious
waste containers (red bags), or regular garbage.
Do not dispose of extracted teeth that contain amalgam restorations in
biohazard containers, infectious waste containers (red bags), sharps
containers, or regular garbage.
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
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.
Where appropriate, disposable amalgam traps are preferable to
reusable traps.
T
T
T
T
T
T
T
T
T
T
T
T(G)
T
T
T(G)
T
T
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Table 4-6. Best Management Practices by Municipality
Best Management Practice
Requirement/Guidance
Municipality
ADA
G
East Bay,
Oakland,
CA
R
King
County,
WA
R
Milwaukee and
Madison, WIa
R
Narragansett
Bay, RI
R
NE Ohio,
Cleveland,
OH
R
Palo
Alto,
CA
R
Vacuum Pumps
Recycle contents retained by the vacuum pump filter or other
amalgam collection device, if they contain amalgam.
Do not rinse vacuum pump filters containing amalgam or other
amalgam collection devices over drains or sinks.
Use line cleaners that minimize the dissolution of amalgam.
Do not use bleach or chlorine-containing cleaners to flush wastewater
lines.
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T(G)
T(G)
T
T
T
T
Other
Any dental practice using mercury should maintain a mercury spill kit
on site and train all staff on mercury spill cleanup response procedure.
Install and use amalgam separators.
T
T
T
T
T
T
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.
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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.
-------
Table 4-7. Summary of Voluntary Programs for Reducing Dental Amalgam Releases to Wastewater
State (Jurisdiction)
Date
Description
Participation Rate
Verification of Participation
California
(Palo Alto, San
Francisco, and
Central Contra
Costa)
No
information
Voluntary installation of amalgam separators and
implementation of BMPs.
65%
Survey conducted by sanitation
districts in 2000.
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 information.
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 information.
Minnesota
(MN Dental
Association)
2001
Voluntary installation of amalgam separators
85% of dentists have committed
to installing separators.
No information.
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%
Sanitation district paid for and
oversaw the installation of all
amalgam separators.
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 information.
-------
Table 4-7. Summary of Voluntary Programs for Reducing Dental Amalgam Releases to Wastewater
State (Jurisdiction)
Date
Description
Participation Rate
Verification of Participation
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 a follow-up survey to the
254 members of the local dental
society.
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 information.
Washington
(WA Dental
Association)
August
2003
Voluntary installation of amalgam separators and
implementation of other BMPs.
80% and anticipates an
additional 16%
No information.
Washington
(Seattle and King
County)
No
information
Significant outreach to dental offices on proper
management of scrap amalgam, proper use of chair-
side 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 County:
Made unannounced visits to 212
dental offices.
Contacted separator vendors to
obtain lists of dental office
customers.
Contacted waste haulers and mail-
away firms to obtain lists of
dental office customers.
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 local dentists to
determine how many clinics use
and/or remove amalgam and how
many had installed amalgam
separators.
Sources: AMSA, 2002; MassDEP, 2007; MU Extension, 2007; Walsh, 2007; KCWTD, 2007; and MMSD, 2008.
-------
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.
4-18
-------
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 mail-
away firms.
4-19
-------
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:
4^20
-------
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.
4-21
-------
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.
4-22
-------
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,
4-23
-------
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:
4-24
-------
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
Method for
demonstrating
compliance
Compliance
tracking
Examples from State Programs
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
of mercury removed by the separator (ME).
DEP inspections (CT).
Web form for providing proof of compliance
(RI).
Examples from Local Programs
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).
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).
4-25
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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).
4-26
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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
-------
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.
5-2
-------
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
A 1000 b
A 1300 a
Amalgam Boss a
Amalgam Collector a
ARU-10 e
Asdexb
Avprox AS-9 e
BullfroHg b
BullfroHg e
Durr 7800/780 lb
ECO II a
Guardian Amalgam
Collector e
Hg Separator e
Hg5a
Hg5 with Effluent Flow
Restrictor a
Hg5 HV a
HglOb
Merc II a
MRUb
MRU lOc a
MSS 1000 a
MSS 2000 b
Purevac Hg a
Manufacturer
Air Techniques
Air Techniques
Hygenitek
R & D Services
Hygenitek
Avprox
American Dental
Accessories
DRNA Dental Recycling
Dental Recycling North
America
Air Techniques
Pure Water Development
Air Techniques
SolmeteX
SolmeteX
SolmeteX
SolmeteX
SolmeteX
Bio-Sym Medical
DRNA Dental Recycling
DRNA/ ADA Technologies
Maximum Separation
Systems
Maximum Separation
Systems
Sultan Healthcare
Treatment Technology
Sedimentation
Sedimentation
Sedimentation, filtration, ion
exchange
Sedimentation
Sedimentation, filtration, ion
Exchange
Filtration
Sedimentation, filtration
Sedimentation, filtration
Sedimentation
Centrifugation
Sedimentation
Sedimentation
Sedimentation, filtration, ion
exchange
Sedimentation, filtration, ion
exchange
Sedimentation, filtration, ion
exchange
Sedimentation, filtration, ion
exchange
Sedimentation, filtration, ion
exchange
Sedimentation, filtration, ion
exchange
Sedimentation, filtration, ion
exchange
Sedimentation, filtration, ion
exchange
Sedimentation, filtration
Sedimentation, filtration
Sedimentation
Percentage of Amalgam
Removal Efficiency d
96.22% c
99.27%
99.17%
99.40%
99.99%
99.23% c
95%-99%
99.13%c
98.3%-99.6%
97.86% c
97.05%
>95%
>98%
98.53%
98.03%
98.88%
99.99% c
98.06%
99.96% c
99.97%
99.54%
99.3% c
99.91%
5-3
-------
Table 5-1. Effectiveness of Amalgam Separators
Model
Rasch 890- 1000 a
Rasch 890-4000 b
Rasch 890-6000 a
REBe
RME 2000 b
Manufacturer
AB Dental Trends
AB Dental Trends
AB Dental Trends
Rebec Simple Solutions
Rebec
Treatment Technology
Sedimentation, filtration, ion
exchange
Sedimentation, filtration, ion
exchange
Sedimentation, filtration, ion
exchange
Sedimentation
Sedimentation
Average
Percentage of Amalgam
Removal Efficiency d
98.94% c
99.92% c
98.3 1%C
96.90%
99.67% c
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:
5-4
-------
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
gray water) and hospitals (AMSA, 2002).
-------
Table 5-2. Impact of BMPs on Mercury Discharged to POTW
BMP Program
California Dental
Association
Corvallis, OR
Springfield, MO
Springfield, MO
Madison, WI
EBMUD
Wichita, KS
Milwaukee, WI
Duluth, MN
Palo Alto, CA
Narragansett Bay,
RI
MCES
Metropolitan
Wastewater
Treatment Plant
MCES
Hastings
Wastewater
Treatment Plant
Description
Voluntary installation of amalgam
separators.
Voluntary installation of amalgam
separators.
BMP outreach program.
BMP outreach program
Voluntary installation of amalgam
separators.
Required installation of amalgam
separators.
Voluntary installation of amalgam
separators.
Required installation of amalgam
separators.
St. Louis River Beneficiary Group
provided a grant to purchase amalgam
separators for all offices.
Required installation of amalgam
separators.
Voluntary installation of amalgam
separators.
Voluntary installation of amalgam
separators.
Community-wide study. MCES
established a baseline, installed the
amalgam separators at dental offices,
conducted sampling, and then removed
the amalgam separators.
Percent of Dentists Using Amalgam
Separators
Before Program
No information
No information
No information
No information
No information
No information
60%
No information
No information
No information
No information
No information
0%
After Program
No information
No information
No information
No information
22% (as of 2005)
96%
99%
No information
100%
96%
No information
No information
100%
(6 facilities total)
Percent Mercury Load
Reduction
78% of amalgam to POTW
79% of POTW influent
34% of POTW influent A a
96% of POTW Influent B b
No trend in POTW influent
No trend in POTW influent
No trend in POTW influent
Decrease in POTW influent
Decrease in POTW sludge
No trend in POTW influent
No trend in POTW influent
50.6% of POTW influent
44% of POTW influent
Source
Condrin. 2004
Lamperti, 2007
MU Extension,
2007
MU Extension,
2007
Walsh, 2007
Walsh, 2007
Walsh, 2007
Walsh, 2007
Walsh, 2007
Walsh, 2007
Walsh, 2007
Nelson, 2007
Nelson, 2007
-------
Table 5-2. Impact of BMPs on Mercury Discharged to POTW
BMP Program
MCES Cottage
Grove Wastewater
Treatment Plant
King County, WA
POTW "A"
POTW "B"
POTW "C"
POTWs "D" and
"E"
POTW "F"
POTW "G"
POTW "H"
POTW "I"
POTWs "F and
"K"
Description
Community-wide study. MCES
established a baseline, installed the
amalgam separators at dental offices,
conducted sampling, and then removed
the amalgam separators.
Voluntary installation of amalgam
separators and mandatory
implementation of BMPs.
Required facilities to either install
amalgam separators or demonstrate
compliance with a mercury limit of
0.005 ppm.
Mandatory BMP program began in
2002. Installation of amalgam separators
was not required.
BMP program began in 2002. Some
BMPs were mandatory. Installation of
amalgam separators was voluntary.
Program required implementation of
BMPs by 2004 and installation of
amalgam separators by 2008.
Voluntary amalgam separator program
began in 1997.
Voluntary installation of amalgam
separators.
Voluntary amalgam separator program
began in 2002.
Mandatory amalgam separator program
began in 2001.
Mandatory program required dentists to
meet a limit of 0.2 mg/L by July 2003.
Percent of Dentists Using Amalgam
Separators
Before Program
0%
No information
0%
5%
6%
0.6%
0%
44%
60%
94%
94%
After Program
87.5%
(7 out of 8 facilities)
95%
100%
9% (out of 2 19
facilities)
6% (out of 18
facilities)
38% (total number of
facilities unknown)
20% (total number of
facilities unknown)
100% (100 facilities
total)
98% (out of -200
facilities)
98% (total number of
facilities unknown)
98% (total number of
facilities unknown)
Percent Mercury Load
Reduction
29% of POTW influent
50% of POTW biosolids
(concentration-basis)
No trend in POTW influent
56.4% of POTW influent
43% of POTW influent
60.5% of influent to POTW
"D";
22.0% of influent to POTW "E"
38.0% of POTW influent
90% increase to POTW influent
No trend in POTW influent
27.5% of POTW influent
8.9% increase to POTW "J";
44. 1% reduction to POTW "K"
Source
Nelson, 2007
King County,
2008
NACWA, 2007a
NACWA, 2007a
NACWA, 2007a
NACWA, 2007a
NACWA, 2007a
NACWA, 2007a
NACWA, 2007a
NACWA, 2007a
NACWA, 2007a
-------
Table 5-2. Impact of BMPs on Mercury Discharged to POTW
BMP Program
POTW "L"
Description
POTW recommends installation of
amalgam separators to dentists.
Percent of Dentists Using Amalgam
Separators
Before Program
No information
After Program
11% (total number of
facilities unknown)
Percent Mercury Load
Reduction
50.6% of POTW influent
Source
NACWA, 2007a
a Northwest Treatment Plant.
b Southwest Treatment Plant.
oo
-------
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
San Francisco, CA
San Francisco, CA
Palo Alto, CA
Palo Alto, CA
Western Lake Superior
District, MN
Salem, OR
Salem, OR
Oregon State
Oregon State
Oregon State
Description
Brochure/fact sheets + distribution
Site visits
Brochure/fact sheets + distribution
Outreach/advisory group
Outreach
Staff labor
Inspection or other form of contact
All costs in 2004
All costs in 2005
All costs in 2006
Total Cost
($2008)
$80,600
$16,100
$16,100
$13,400
$40,300
$8,330
$4,880
$3,950
$1,420
$6,380
Number of
Participants
900
35 visits
500
500
100
109
109
53
26
36
Source
AMSA, 2002
AMSA, 2002
AMSA, 2002
AMSA, 2002
AMSA, 2002
ACWA, 2007
ACWA, 2007
ACWA, 2007
ACWA, 2007
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.
5-9
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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.
' Mention of product and vendor names does not constitute an endorsement by EPA.
5-10
-------
Table 5-4. Cost of Purchasing, Operating and Maintaining Amalgam Separators ($2008)
Model
A1000
A110
A1200
A1300
A1400
Amalgam
Collector
ARU-10
Avprox Asdex
Avprox AS-9
BullfroHg
Catch Hg 400
Series
Manufacturer
Air Techniques
Air Techniques
Air Techniques
Air Techniques
Air Techniques
R & D Services
Hygenitek
American
Dental
Accessories
American
Dental
Accessories
Dental
Recycling
North America
Rebec
MSRP
$1,010
$2,020
$2,020
$4,030
$4,340
$470-$ 1,680
$671-$928
Lease: $52/mo
$289
$309
Purchase: $934
Lease: $134/mo
(2 -year minimum)
$1,320
Maintenance
Replace collecting
containers every 6 months
Replace collecting
containers every 6 months
Replace collecting
containers every 6 months
Replace collecting
containers every 6 months
Replace collecting
containers every 6 months
Conduct weekly
maintenance and decant
treated wastewater
Replace unit every 9 to 12
months
Sludge removal every 2 to
5 years
Replace canister every 6
months
Replace sedimentation tank
every 6-24 months
Replace canister every 4-6
weeks
Replace filter every 3-8
months
Replace separator annually
Annual recycling required
Replacement Parts
Filter: $672
Replacement kit: $1,010
Replacement kit: $1,010
Replacement kit: $1,010
Replacement kit: $1,010
Unknown
Filter canister: $133-$202
Sedimentation tank: $79-
$101
Canister: $47
Filter: $106
Unknown
Included in lease
Annual recycling: $531
Recycling?
Not
included
Included
Included
Included
Included
Not
included
Included
Not
included
Not
included
$605 /year
Included
First Year
Cost
$1,010
$2,020
$2,020
$4,030
$4,340
$470-$ 1,680
$977-$ 1,3 80
$697-$901
$468-$734
$1,540
$1,860
Other
Year Costs
$672
$1,010
$1,010
$1,010
$1,010
Unknown
$306-$605
$408-$612
$159-$425
$605
$531
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Table 5-4. Cost of Purchasing, Operating and Maintaining Amalgam Separators ($2008)
Model
Catch Hg 1000
Series
Durr System
7800/7801
ECO II
Guardian
Amalgam
Collector
Hg5
HglO
Merc II
MSS Model
1000
MSS Model
2000
REB 1000
REB 5000
REB 7000
REB 9000
Rasch 890-
1000
Manufacturer
Rebec
Air Techniques
Pure Water
Development
Air Techniques
Solmtex
Solmtex
Bio-Sym
Medical
Maximum
Separation
Systems
Maximum
Separation
Systems
Rebec Simple
Solutions
Rebec Simple
Solutions
Rebec Simple
Solutions
Rebec Simple
Solutions
AB Dental
Trends
MSRP
$2,550-$4,030
$5,380
Purchase: $739
Lease: $73/mo
$2,020-$4,380
$934
(1-10 chairs)
$10,010
(>10 chairs)
$1,200-$ 1,740
$1300-$1,880
$4,030
$2,550
$2,550
$2,550
$4,030
$1,600
Maintenance
Annual recycling required
Replace cassette once per
year
Apply recommended
cleanser daily
Replace separator annually
Replace collection
container every 6 to 12
months
Replace cartridge every 6
months
Replace cartridge every 6
months
Replace unit annually
Replace settling tank
annually
Replace settling tank
annually
Annual recycling required
Annual recycling required
Annual recycling required
Annual recycling required
Replace canister every 12-
18 months
Replacement Parts
Annual recycling: $531-
$665
Cassette: $128
Cleanser: $101
Replacements are included
under the lease
Replacement kit: $1010
Resin cartridge: $202-$370
Filter: $101-$202
Resin cartridge: $202-$370
Filter: $101-$202
Replacement unit installation
and disposal: $665
Settling tank: $222
Tank recycling: $249
Cleanser: $101
Settling tank: $222
Tank recycling: $249
Cleanser: $101
Replacement parts: $531
Replacement parts: $531
Replacement parts: $665
Replacement parts: $531
Canister: $801
Recycling?
Included
Included
Included
Included
Not
included
Not
included
Included
Not
included
Not
included
Included
Included
Included
Included
Included
First Year
Cost
$3,080-$4,690
$5,380
$840
$2,020-$4,380
$1,240-$1,510
$10,300-
$10,590
$1,200-$ 1,740
$1,300-$1,400
$4,030
$2,550
$2,550
$2,550
$4,030
$1,600
Other
Year Costs
$531-$665
$128
$101
$1,010
$605-
$1,140
$605-
$1,140
$665
$571
$571
$531
$531
$665
$531
$801
-------
Table 5-4. Cost of Purchasing, Operating and Maintaining Amalgam Separators ($2008)
Model
Rasch 890-
4000
Rasch 890-
6000
Average
Manufacturer
AB Dental
Trends
AB Dental
Trends
MSRP
$2,220
$895
$2,320
Maintenance
Replace canister every 12-
18 months
Replace canister every 12-
18 months
Replacement Parts
Canister: $1,010
Canister: $801
Recycling?
Included
Included
First Year
Cost
$2,220
$895
$2,550
Other
Year Costs
$1,008
$801
$657
Table adapted from EBMUD, 2002 and 2004; McManus and Fan, 2003. Journal of the American Dental Association. Purchasing, Installing and Operating
Dental Amalgam Separators. Volume 134, August 2003 (pp. 1054-1059).
-------
Table 5-5. Estimated Purchase, Installation, and O&M Costs of Amalgam Separator
($2008)
Source
Metropolitan Council Environmental Services
and the Minnesota Dental Association (MCES,
2001)
Association of Metropolitan Sewerage Agencies
(AMSA, 2002)
King County (WA) Department of Natural
Resources and Parks (King County, 2005)
Palo Alto (CA) Regional Water Quality Control
Plant (RWQCP), Amalgam Recovery Program
(Palo Alto, 2007)
Binational Toxics Strategy Mercury Workgroup,
Great Lakes National Program Office, U.S. EPA
(EPA, 2003)
Vandeven and McGinnis a (Vandeven and
McGinnis, 2004)
Bates (Bates, 2006)
U.S. EPA (EPA, 2003)
Journal of the California Dental Association
(Condrin, 2004)
(Behm, 2008)
Average b
Purchase Cost
Low
$221
$134
$171
$181
$393
$1,200
$600
$283
High
$4,840
$4,030
$2,280
$2,410
$3,930
$2,410
$1,500
$3,170
Installation Cost
Low
$228
$60
$262
$200
$188
High
$571
$1,204
$262
$600
$659
O&M Cost
Low
$415
$565
$228
$301
$748
$98
$361
$388
High
$691
$3,230
$799
$722
$1,070
$983
$602
$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
Average cost of purchase (Table 5-4)
Average cost of purchase range (Table 5-5)
Average annual cost of O&M (Table 5-4)
Average annual cost of O&M range (Table 5-5)
Cost ($2008)
$2,320
$283-$3,170
$657
$388-$!, 160
5-14
-------
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)
Purchase
Installation
Maintenance
Replacement
Estimated annual cost
Small (1-4 Chairs)
$228-$l,370
$114-$228
$0-$228
$57-$856
$211-$1,073
Medium (5-12 Chairs)
$760-$2,510
$143-$297
$0-$228
$86-$856
$293-$!, 110
Large (+12 Chairs)
$2,850-$ 10,000
$228-$!, 140
$0-$228
$571-$2,400
$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 costsincluding recyclingrange 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).
5-15
-------
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 assuminglOO 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.
6-1
-------
Table 6-1. Estimate of Total Number of Dentists
Description
Total number of active dentists
Number of general dentists
Number of specialists
Number of specialists in fields
that use amalgam
Total number of dental facilities
Value
162,181
129,745
32,436
11,353
122,918
Type
Data
Estimation
Estimation
Estimation
Data
Calculation
None
80% of total dentists
20% of total dentists
35% of specialists that work in
fields that use amalgam
None
Source/Notes
ADA, 2007b
ADA, 2007b
ADA, 2007b
Vandevin &
McGuiness, 2005
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
Number of total restorations
performed in US in 1999
Mercury content of amalgam
capsule
Amount of mercury used for
restoration
Amount of mercury disposed
of as non-contact scrap
amalgam
Amount of mercury used per
restoration that is discharged
to wastewater
Total amount of mercury
discharged to wastewater
from restorations
Value
71,000,000
450 mg
340 mg
HOmg
31 mg
2.40 tons
Type
Data
Data
Data
Data
Estimation
Result
Calculation
None
None
None
None
9% of the amount of mercury used
for restorations
Product of number of restorations
performed (71,000,000) and
amount of mercury used per
restoration that is discharged to
wastewater (31 mg)
Source
Vandeven and
McGinnis, 2005
Vandeven and
McGinnis, 2005
Vandeven and
McGinnis, 2005
Vandeven and
McGinnis, 2005
Vandeven and
McGinnis, 2005
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
Total number of removals
per general dentist per year
Total number of removals
per specialist per year
Value
710
440
Type
Data
Data
Calculation
None
None
Source
Vandeven and McGinnis,
2005
Vandeven and McGinnis,
2005
6-2
-------
Table 6-3. Determining the Total Mercury Discharge from Amalgam Removals
Description
Total number of removals by
general dentists
Total number of removals by
specialists
Total number of removals
Mercury content of amalgam
removed
Amount of mercury per
removal that is discharged to
wastewater
Total amount of mercury
discharges to wastewater
from amalgam removals
Value
92,118,808
4,995,175
97,113,983
300 mg
270 mg
27.4 tons
Type
Estimation
Estimation
Estimation
Data
Assumption
Result
Calculation
Product of removals by
general dentists (710)
and number of general
dentists (129,745)
Product of removals by
specialist (440) and
number of specialists
who work in fields that
use amalgam (11,353)
Sum the number of
removals by performed
by general dentists and
specialists
None
90% of mercury content
of amalgam removed
Product of amount of
mercury per removal
that is discharged to
wastewater (270 mg)
and total number of
removals (97,113,983)
Source
See Table 6-1
See Table 6-1
Vandeven and McGinnis,
2005 a
Vandeven and McGinnis,
2005
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.
6-3
-------
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
Number of facilities using
only chair-side traps
Number of facilities using
chair-side traps and vacuum
pump filters
Number of facilities using
chair-side traps, vacuum
pump filters, and amalgam
separators
Removal efficiency of chair-
side trap
Removal efficiency of chair-
side trap + vacuum pump
filter
Removal efficiency of chair-
side trap, vacuum pump
filter, and amalgam separator
Mercury discharges from
facilities using only chair-
side traps
Mercury discharges from
facilities using only chair-
side traps and vacuum pump
filters
Value
24,584
49,167
49,167
0.680
0.810
0.991
2.00 tons
2.38 tons
Type
Assumption
Assumption
Assumption
Data
Data
Data
Estimation
Estimation
Calculation
20% of all dental facilities
use only chair-side traps
40% of dental facilities use
only chair-side traps and
vacuum pump filters
40% of dental facilities use
amalgam separators, vacuum
pump filters, and chair-side
traps
None
None
None
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
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
Source
Vandeven and McGinnis,
2005
Vandeven and McGinnis,
2005
See Table 6-8
Vandeven and McGinnis,
2005
Vandeven and McGinnis,
2005
Median of amalgam
separator efficiencies in
Table 5-1 of Section 5.1
See Table 6-1 and Section
6.2
See Table 6-1 and Section
6.2
6-4
-------
Table 6-4. Determining the Baseline Mercury Discharge to Wastewater
Description
Mercury discharges from
facilities using chair-side
traps, vacuum pump filters,
and amalgam separators
Total baseline mercury
discharges to POTWs
POTW removal efficiency
Total baseline mercury
discharges to receiving
streams
Value
0.11 tons
4.50 tons
0.90
0.45 tons
Type
Estimation
Result
Data
Result
Calculation
Product of the ratio of the
number of facilities using
amalgam separators, chair-
side 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
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)
None
Amount of mercury
discharged to receiving
stream after POTW
removal (4.50(1-0.9))
Source
See Table 6-1 and Section
6.2
Median POTW removal
efficiency (EPA, 1982)
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
Total baseline mercury
discharges to POTWs for
facilities that do not operate
amalgam separators
Number of additional
facilities that would install
99.2 percent efficiency
amalgam separators
Value
4.38 tons
73,751
Type
Estimation
Estimation
Calculation
Sum of discharges from facilities
that use only chair-side traps (2.00
tons) and vacuum pump filters
(2.38 tons)
Sum of facilities that use only
chair-side traps (24,584) and
vacuum pump filters (49,167)
Source
See Table 6-4
See Table 6-4
6-5
-------
Table 6-5. Potential Reductions of Mercury to POTWs from Mandatory Installation of
Amalgam Separators
Description
Mercury discharges after
installation of amalgam
separators at these facilities
Reduction of mercury
discharges to POTWs
Total mercury discharges to
POTWs following
mandatory installation of
Amalgam Separators
POTW removal efficiency
Total discharges to
receiving stream
Total reductions to
receiving stream
Value
0.175 tons
4.21 tons
0.29 tons
0.90
0.029 tons
0.421 tons
Type
Estimation
Estimation
Result
Estimation
Result
Result
Calculation
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.
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)
Sum of mercury dischargers
after installation of amalgam
separators (0.175 tons) and from
current facilities using chair-
side traps, vacuum pump filters,
and amalgam separators (0.11
tons).
Amount of mercury discharged
to receiving stream after POTW
removal (0.29(1-0.9))
Difference of total baseline
mercury discharges to receiving
stream (0.45 tons) and total
discharges to receiving stream
(0.029 tons)
Source
See Table 6-1,
Table 6-4, and
Section 6.2
See Table 6-4
Median POTW
removal efficiency
(EPA, 1982)
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.
6-6
-------
Table 6-6. Calculation of Cost
Description
First year cost of amalgam separator
unit
Annual cost for amalgam separator
after first year
Lifetime of separator (years)
Interest rate
Capital recovery factor
Annualized capital investment cost
Total annualized cost
Cost ($2008)
$2,550.00
$657.00
10
0.07
0.14
$363.06
$1,020.06
Reference
Average cost from Table 5-4
Average cost from Table 5-4
Vandeven and McGinnis, 2005
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
Tons of mercury discharged to POTW from dental
facilities
Tons of mercury discharged to surface water a
Mercury TWPE discharged to surface water (Ib-eq)
Reduction of mercury discharges to POTWs (tons)
Reduction of mercury discharges to receiving
stream (tons)
Reduction of mercury TWPE to receiving stream
(lb-eq)b
Number of facilities to install amalgam separators °
Cost to industry ($2008) (assumes 1 separator per
facility)
Baseline
4.50
0.45
105,000
0
0
0
0
$0.00
100% Amalgam Separator
Installation
0.29
0.029
6,790
4.21
0.421
98,200
73,800
$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.
6-7
-------
Table 6-8. Number of Dental Facilities and Amalgam Separator Use by State
State
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut b
Delaware
District of Columbia
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine b
Maryland
Massachusetts b
Michigan
Minnesota °
Mississippi
Missouri
Montana
Nebraska
Nevada
New Hampshire b
New Jersey b
New Mexico
New York b
North Carolina
North Dakota
Ohio
Oklahoma
Oregon b
Pennsylvania
Rhode Island b
South Carolina
NAICS 621210 Dental
Offices
478
560
263
3,050
412
1,732
9,017
4,546
5,258
4,357
2,334
5,639
4,353
2,023
1,922
1,077
2,153
259
267
790
1,016
243
2,483
315
2,845
573
2,720
1,368
3,024
6,733
1,586
2,110
1,417
846
933
1,527
1,325
7,597
414
656
222
Assumed Percent
Operating Amalgam
Separators a
0.2
0.2
0.2
0.2
0.2
0.2
1
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
1
0.2
1
0.2
0.85
0.2
0.2
0.2
0.2
0.2
1
1
0.2
1
0.2
0.2
0.2
0.2
1
0.2
1
0.2
Estimated Number
Operating Amalgam
Separators
96
112
53
610
82
346
9,017
909
1,052
871
467
1,128
871
405
384
215
431
52
53
790
203
243
497
268
569
115
544
274
605
6,733
1,586
422
1,417
169
187
305
265
7,597
83
656
44
6-8
-------
Table 6-8. Number of Dental Facilities and Amalgam Separator Use by State
State
South Dakota
Tennessee
Texas
Utah
Vermont b
Virginia
Washington0
West Virginia
Wisconsin
Wyoming
Total U.S.
NAICS 621210 Dental
Offices
2,366
593
2,209
1,418
883
3,183
1,825
19,005
307
686
122,918
Assumed Percent
Operating Amalgam
Separators a
0.2
0.2
0.2
0.2
1
0.2
0.8
0.2
0.2
0.2
Percent of Total Dental Offices
Estimated Number
Operating Amalgam
Separators
473
119
442
284
883
637
1,460
3,801
61
137
49,021
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.
6-9
-------
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Bacteria That Methylate Mercury Thrive in Wastewater Found Downstream from Dental Traps."
Environmental Science & Technology Online News. 12 March.
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ACWA. 2007. Oregon Association of Clean Water Agencies. "EPA Comment Letter Docket
ID No. EPA-HQ-OW-2006-0771." December.
ADA. 2007a. American Dental Association. Best Management Practices for Amalgam Waste.
Updated July 2007. DCN 04244.
ADA. 2007b. American Dental Association. Survey and Economic Research on Dentistry,
Frequently Asked Questions: How Many Dentists Are There in the U.S. ?
http://www.ada.org/ada/prod/survey/faq.asp#howmany. DCN 05992.
ALISON. 2007. Alabama Legislative Information System Online. Regular Session 2004.
http://alisdb.legislature.state.al.us/acas/ACASLogin.asp. DCN 05993.
AMSA. 2002. Association for Metropolitan Sewerage Agencies. Mercury Source Control and
Pollution Prevention Program Evaluation, Final Report. EPA-HQ-OW-2006-0771-0849[1].9.
July. DCN: 04225.
Anderson, N. 2007. Statement of Norris Anderson, Ph.D., Director, Office of Science and Health
Coordination, FDA. November 14. http://www.fda.gov/ola/2007/dentalmercurylll407.html.
DCN 05979.
APHA, AWWA, and WEF: Standard Methods for the Examination of Water and Wastewater,
1998. Washington, DC. DCN 06113.
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