United States	Office of Water	EPA-821-R-16-005
Environmental Protection	Washington, DC 20460 December 2016
Agency
<8»Efi
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*»EPA
United States
Environmental Protection
Agency
Technical and Economic Development Document
for the Final Effluent Limitations Guidelines and
Standards for the Dental Category
(40 CFR 441)
EP A-821 -R-16-005
December 2016
U.S. Environmental Protection Agency
Office of Water (4303T)
Engineering and Analysis Division
1200 Pennsylvania Avenue, NW
Washington, DC 20460
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Acknowledgements and Disclaimer
This document was prepared by the Environmental Protection Agency. Neither the United States
Government nor any of its employees, contractors, subcontractors, or their employees make any
warrant, expressed or implied, or assume any legal liability or responsibility for any third party's
use of or the results of such use of any information, apparatus, product, or process discussed in
this report, or represents that its use by such party would not infringe on privately owned rights.
Questions regarding this document should be directed to:
U.S. EPA Engineering and Analysis Division (4303T)
1200 Pennsylvania Avenue NW
Washington, DC 20460
(202) 566-1000
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Table of Contents
TABLE OF CONTENTS
Page
Chapter 1 Background	1-1
1.1	Legal Authority	1-1
1.2	Regul atory B ackground	1-1
1.2.1	Clean Water Act	1-1
1.2.2	The National Pretreatment Program, 40 CFR 403	1-4
1.3	Regulatory History Of The Dental Category	1-5
1.3.1	Detailed Study of the Dental Category	1-5
1.3.2	2008 Memorandum of Understanding on Reducing Mercury
Discharges	1-6
1.3.3	ADA Best Management Practices and Support for a National
Rulemaking	1-6
1.3.4	Proposed Rule for the Dental Category	1-6
1.3.5	State and Local Programs	1-7
1.3.6	Minamata Convention on Mercury	1-7
1.4	References	1-7
Chapter 2 Summary and Scope	2-1
2.1	Summary Of The Final Rule	2-1
2.2	Applicability Of The Final Rule	2-4
2.3	Subcategorization	2-4
2.3.1	Subcategorization Factors	2-5
2.3.2	Analysis of Subcategorization Factors	2-5
2.3.3	Office Configuration	2-6
2.4	References	2-7
Chapter 3 Data Collection Activities	3-1
3.1	Health Services Industry Detailed Study	3-1
3.2	EPA Strategies To Reduce Mercury Discharges	3-1
3.3	Literature Revi ew	3-2
3.4	Meetings With Stakeholders	3-2
3.4.1	Environmental Council of the States	3-2
3.4.2	Association of Clean Water Act Administrators	3-3
3.4.3	Environmental Organizations	3-3
3.4.4	American Dental Association (ADA)	3-3
3.4.5	National Association of Clean Water Agencies (NACWA)	3-3
3.5	Amalgam Separator Manufacturers (Vendor Contacts)	3-3
3.6	Air Force Study	3-4
3.7	References	3-4
Chapter 4 Profile of Dental Industry	4-1
4.1	Number Of Dental Offices	4-1
4.2	Specialty Practices At Dental Offices	4-3
4.3	Discharge Information	4-4
4.4	References	4-5
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Table of Contents
Chapter 5 Dental Amalgam Waste, Pollutants of Concern, and POTW Pass
Through	5-1
5.1	Sources Of Dental Amalgam In Wastewater From Dental Offices	5-1
5.2	Dental Office Configuration	5-2
5.3	Pollutants Of Concern And Pass Through	5-3
5.3.1 POTW Pass Through Analysis	5-3
5.4	References	5-5
Chapter 6 Current National, State, and Local Dental Mercury Reduction
Programs	6-7
6.1	National Dental Amalgam Requirements	6-7
6.1.1	Resource Conservation and Recovery Act (RCRA)	6-7
6.1.2	Occupational Safety and Health Administration	6-8
6.1.3	Food and Drug Administration	6-8
6.2	National Dental Amalgam Guidance	6-8
6.2.1	ADA Best Management Practices	6-9
6.2.2	ADA Nine Principles	6-10
6.2.3	ADA Health First Amalgam Recovery Program	6-11
6.3	State Dental Amalgam Requirements	6-11
6.4	Local Dental Amalgam Requirements	6-16
6.5	Voluntary Programs	6-19
6.5.1	Voluntary Programs with High Participation Rates	6-19
6.5.2	Voluntary Programs with Low Participation Rates	6-23
6.5.3	Summary of Participation Rates in Voluntary Programs	6-26
6.6	References	6-26
Chapter 7 Treatment Technologies and Best Management Practices
(BMPs)	7-1
7.1	Amalgam Separators	7-1
7.1.1	Treatment Process, Design, and Operation	7-1
7.1.2	Standards for Amalgam Separators	7-3
7.1.3	Treatment Efficiencies for Amalgam Separators	7-4
7.2	Polishing	7-7
7.3	Wastewater Retention Tanks	7-9
7.4	Best Management Practices	7-9
7.5	References	7-9
Chapter 8 Regulatory Options	8-1
8.1	Pretreatment Standards For Existing Sources (PSES)	8-1
8.2	Pretreatment Standards For New Sources (PSNS)	8-2
8.3	References	8-2
Chapter 9 Costs of Technologies	9-1
9.1	Methodology For Developing Model Dental Office Costs	9-1
9.1.1	Model Dental Offices	9-2
9.1.2	Incremental Compliance Costs for Model Dental Offices	9-2
9.2	References	9-15
in
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Table of Contents
Chapter 10 Economic Impacts for the Dental Industry	10-1
10.1	Overview Of Dental Offices Potentially Subject To Final Regulation	10-1
10.1.1	Number of Dental Offices Potentially Subject to the Final
Regulation 10-2
10.1.2	Adjustments to Account for Baseline Status	10-4
10.2	Summary Of The Final Regulation And Compliance Costs	10-5
10.2.1	Summary of Compliance Costs	10-5
10.2.2	Linking Compliance Costs By Number of Chairs to Dental Offices
by Revenue Range	10-10
10.2.3	Estimated Cost of Compliance to Dental Offices	10-14
10.3	Economic Impact Of Compliance Costs	10-14
10.3.1	Cost-to-Revenue Analysis	10-15
10.3.2	Ratio of the Final Rule's Capital Costs to Total Dental Office
Capital Assets	10-19
10.3.3	Ratio of the Final Rule's Capital Costs to Annual Dental Office
Capital Replacement Costs	10-21
10.3.4	Economic Impact for New Sources	10-25
10.4	Social Cost Of The Final Dental Amalgam Rule	10-25
10.4.1	Cost of Compliance on Social Cost Basis	10-26
10.4.2	Administrative Costs	10-26
10.4.3	Total Social Cost	10-27
10.5	Regulatory Flexibility Act Assessment	10-27
10.6	References	10-29
Chapter 11 Pollutant Reduction Estimates	11-1
11.1	National Estimate Of Annual Pollutant Loadings From Dental Offices	11-1
11.1.1	National Estimate of Annual Mercury in Dental Office Wastewater.... 11-1
11.1.2	National Estimate of Annual Baseline Mercury Discharges from
Dental Offices to POTWs	11-3
11.1.3	National Estimate of Annual Non-Mercury Amalgam Metals in
Dental Offices Wastewater	11-4
11.1.4	National Estimate of Annual Baseline Discharges of Non-Mercury
Amalgam Metals from Dental Offices to POTWs	11-5
11.1.5	Total Annual Baseline Discharges to POTWs	11-5
11.2	National Estimate Of Annual Pollutant Reductions To POTWs Associated
With The Final Dental Category Rule	11-5
11.3	National Estimate Of Annual Pollutant Reductions To Surface Waters
Associated With The Final Dental Category Rule	11-5
11.4	References	11-6
Chapter 12 Cost-Effectiveness Analysis	12-1
12.1	Total Incremental Annualized Compliance Costs	12-1
12.2	Toxic Weighting Factors	12-1
12.3	Calculation Of Annual Total Incremental Pound-Equivalents Removed To
Surface Waters	12-2
12.4	Cost-Effectiveness Results	12-3
12.5	References	12-3
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Table of Contents
Chapter 13 Environmental Impacts of Dental Mercury Discharges	13-1
13.1	Mercury In Dental Wastewater	13-1
13.2	Dental Mercury Fate And Transport	13-2
13.3	Environmental Assessment	13-2
13.3.1	Mercury in Surface Water Di scharges	13-2
13.3.2	Mercury in Biosolids	13-3
13.3.3	Environmental Benefits of the Final Rule	13-4
13.4	References	13-4
Chapter 14 Non-Water-Quality Environmental Impacts	14-1
14.1	Energy Requirements	14-1
14.2	Solid Waste Generation	14-2
14.3	Air Emissions	14-2
14.4	References	14-3
Chapter 15 Implementation	15-1
15.1	Compliance Deadline	15-1
15.2	Summary Of Dental Office Responsibilities	15-1
15.3	Control Authority Oversight/Reporting	15-4
15.4	Variances	15-5
15.5	Phase-Out Of The Rule	15-5
15.6	References	15-6
Chapter 16 Quality Assurance Activities for the Dental Category Costing
and Loading Analyses	16-1
16.1	Cost Drivers and Uncertainty with Compliance Costs	16-1
16.2	Development of Cost Calculation Spreadsheets	16-3
16.3	Activities for the Dental Category Loading Analysis	16-5
16.3.1 Development of Loadings Calculations	16-9
16.4	Sensitivity Analysis for Costs	16-9
16.4.1	Sensitivity Analysis for Amalgam Separator Purchase Costs	16-10
16.4.2	Sensitivity Analysis for Amalgam Separator Replacement Part
Costs	16-11
16.4.3	Sensitivity Analysis for Amalgam Separator Maintenance Costs	16-13
16.5	Sensitivity Analysis for Loadings	16-15
16.5.1	Sensitivity Analysis for Number of Amalgam Placements
Performed Annually by Dental Offices	16-15
16.5.2	Sensitivity Analysis for Number of Amalgam Removals Performed
Annually by Dental Offices	16-17
16.5.3	Sensitivity Analysis on the Efficiency of Chair-Side Traps and
Vacuum Filters	16-17
16.5.4	Sensitivity Analysis for Dissolved Mercury Concentration in the
Wastewater	16-19
16.6	NACWADATA	16-19
16.7	References	16-20
Chapter 17 Glossary and List of Acronyms	17-1
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List of Tables
LIST OF TABLES
Page
Table 4-1. Number of Dental Offices by State (2012)	4-2
Table 4-2. Growth in Number of Dental Offices (1997 to 2012)	4-3
Table 4-3. Dental Offices with NPDES Permits in Integrated Compliance Information
System -NPDESa	4-5
Table 6-1. ADA BMPs for Dental Amalgam	6-9
Table 6-2. Summary of Elements of State Requirements	6-12
Table 6-3. Mandatory BMPs by State and Comparison to ADA BMPs a'b	6-13
Table 6-4. Voluntary BMPs by State and Comparison to ADA BMPs	6-15
Table 6-5. Number of Dental Offices Located in States and Localities with Dental
Amalgam Control Program	6-17
Table 6-6. Summary of Voluntary Programs for Reducing Dental Amalgam Releases to
Wastewater	6-21
Table 7-1. Efficiency and Technology of 26 Amalgam Separators	7-5
Table 9-1. Cost of Purchasing, Operating, and Maintaining Amalgam Separators ($2016)	9-4
Table 9-2. Summary of One-time Incremental Compliance Costs ($2016) to Model
Dental Offices to Initially Purchase and Install Amalgam Separators	9-9
Table 9-3. Burden Estimate for One-time Compliance Report	9-10
Table 9-4. Summary of One-Time Compliance Report Costs ($2016) to Model Dental
Offices	9-10
Table 9-5. Vacuum System Labor Cost Offset for Model Dental Offices Purchasing and
Installing Amalgam Separators	9-12
Table 9-6. Summary of Annual Costs ($2016) to Model Dental Offices Purchasing and
Installing Amalgam Separators	9-13
Table 9-7. Summary of Annual Costs ($2016) to Model Dental Offices with an Amalgam
Separator in Place	9-14
Table 9-8. Summary of Annual Recordkeeping Costs ($2016) to Model Dental Offices	9-15
Table 10-1. Dental Office Establishments by Revenue Range (NAICS 621210, Offices
of Dentists)	10-3
Table 10-2. Establishments Assigned to Regulation Analysis Category	10-5
Table 10-3. Dental Office Compliance Costs by Number of Chairs, Offices with No
Technology in Place (2016$)	10-6
Table 10-4. Dental Office Compliance Costs by Number of Chairs, Offices with
Technology in Place (2016$)	10-7
Table 10-5. Summary of Annualized Compliance Costsa for Dental Office with No
Technology in Place (2016$)	10-9
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List of Tables
Table 10-6. Summary of Annualized Compliance Costs3 for Dental Office with
Technology in Place (2016$)	10-9
Table 10-7. Distribution of the Number of Chairs in Dental Offices	10-11
Table 10-8. Number of Chairs in Dental Offices by Revenue Range	10-12
Table 10-9. Annualized Costs to Complying Dental Offices by Number of Chairs	10-14
Table 10-10. Revenue Range/Number-of-Chairs Combinations for Cost Impact Analysis.... 10-15
Table 10-11. Cost-to-Revenue Analysis Impact Summary3	10-19
Table 10-12. Cost-to-Revenue Analysis Impact Summary by Number of Chairs3	10-19
Table 10-13. Initial Compliance Outlay as a Percentage of Baseline Assets	10-21
Table 10-14. Cost of Dental Equipment for Six-Chair Office by Equipment Life	10-22
Table 10-15. Initial and Annual Replacement Outlay for Startup Dental Office by
Number of Chairs (2016$)a	10-23
Table 10-16. Comparing Total Initial Compliance Outlay to Steady State Annual
Replacement Outlay by Number of Chairs (Chapter 10.3.3; 2016$)	10-24
Table 10-17. Comparing Total Initial Compliance Outlay to Initial Outlay by Number of
Chairs (Chapter 10.3.4; 2016$)	10-24
Table 10-18. Compliance Costs on a Social Cost Basis for Final Dental Amalgam Rule	10-26
Table 10-19. Summary of Social Cost for Final Dental Category Rule	10-27
Table 10-20. Cost-to-Revenue Impact Analysis for Small Entities3	10-28
Table 11-1. Mercury Waste Generation from the Restoration of Dental Amalgam	11-2
Table 11-2. Mercury Waste Generation from the Removal of Dental Amalgam	11-2
Table 11-3. Annual Untreated Mercury Generation from the Restoration and
Removal of Dental Amalgam	11-3
Table 11-4. Dental Office Use and Mercury Removal Efficiency by Treatment
Technology	11-4
Table 11-5. Calculation of Annual Untreated Non-Mercury Metal Generation from the
Restoration and Removal of Dental Amalgam	11-4
Table 12-1. Annualized Compliance Costs at Promulgation Year	12-1
Table 12-2. Toxic Weighting Factors for Pollutants in Dental Amalgam	12-2
Table 12-3. Total Incremental Pound-Equivalents Removed from Surface Water
Discharges3	12-3
Table 12-4. PSES Cost-Effectiveness Analysis	12-3
Table 13-1. Mean Concentrations of Mercury Species in Dental Wastewater	13-1
Table 15-1. Compliance Deadline for Dental Offices Subject to the Final Rule	15-1
Table 16-1. Dental Industry Cost Breakout by Component (Millions; 2016$)	16-9
Table 16-2. Range of Amalgam Separator Purchase Costs ($2016) by Model Dental
Office	16-10
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List of Tables
Table 16-3. Annualized Amalgam Separator Purchase Costs ($2016) by Model Dental
Office	16-11
Table 16-4. Range of Annual Replacement Part Costs ($2016) by Model Dental Office	16-12
Table 16-5. Total Annual Incremental Compliance Costs Based on the Range of
Replacement Part Costs by Model Dental Office	16-13
Table 16-6. Range of Annual Maintenance Costs ($2016) Based on Frequency of
Maintenance	16-14
Table 16-7. Total Annual Incremental Compliance Costs Based on the Range of
Maintenance Frequency by Model Dental Office	16-15
Table 16-8. Impact of Dental Amalgam Placements on Annual Mercury Loadings	16-16
Table 16-9. Impact of Chair-Side Trap Capture Efficiencies on Annual Mercury Loadings.. 16-18
Table 16-10. Impact of Chair-Side Trap and Vacuum Filter (Combined) Capture
Efficiencies on Annual Mercury Loadings	16-18
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List of Figures
LIST OF FIGURES
Page
Figure 5-1. Typical Amalgam Separator Plumbing Configuration in a Dental Office	5-2
IX
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Chapter 1—Background
Chapter 1
Background	
This chapter provides background information on the development of final effluent
limitations guidelines and standards (ELGs) for the dental category. Chapters 1.1 and 1.2 present
the legal authority and discuss the regulatory background for the final rule, respectively. Chapter
1.3 provides a history of activities related to the dental category rulemaking.
1.1	Legal Authority
The U.S. Environmental Protection Agency (EPA) is promulgating ELGs for the dental
category (40 CFR 441) under the authorities of sections 101, 301, 304, 306, 307, 308, and 501 of
the Clean Water Act (CWA), 33 U.S.C. 1251, 1311, 1314, 1316, 1317, 1318, 1342 and 1361 and
pursuant to the Pollution Prevention Act of 1990, 42 U.S.C. 13101 et seq.
1.2	Regulatory Background
1.2.1 Clean Water Act
Congress passed the Federal Water Pollution Control Act Amendments of 1972, also
known as the Clean Water Act (CWA), to "restore and maintain the chemical, physical, and
biological integrity of the Nation's waters." (33 U.S.C. 1251(a)). The CWA establishes a
comprehensive program for protecting our nation's waters. Among its core provisions, the CWA
prohibits the discharge of pollutants from a point source to waters of the U.S. except as
authorized under the CWA. Under section 402 of the CWA, EPA authorizes discharges by a
National Pollutant Discharge Elimination System (NPDES) permit. The CWA establishes a two-
pronged approach for these permits: technology-based controls that establish the floor of
performance for all dischargers, and water quality-based limits where the technology-based
limits are insufficient for the discharge to meet applicable water quality standards. To serve as
the basis for the technology-based controls, the CWA authorizes EPA to establish national
technology-based effluent limitations guidelines and new source performance standards for
discharges from different categories of point sources, such as industrial, commercial, and public
sources, that discharge directly into waters of the U.S.
Direct dischargers (those discharging directly to surface waters) must comply with
effluent limitations in NPDES permits. Technology-based effluent limitations in NPDES permits
for direct dischargers are derived from effluent limitations guidelines (CWA section 301 and
304) and new source performance standards (CWA section 306) promulgated by EPA, or based
on best professional judgment where EPA has not promulgated an applicable effluent guideline
or new source performance standard (CWA section 402(a)(1)(B) and 40 CFR 125.3). The
effluent guidelines and new source performance standards established by regulation for
categories of industrial dischargers are based on the degree of control that can be achieved using
various levels of pollution control technology, as specified in the Act.
EPA promulgates national effluent limitations guidelines and standards of performance
for major industrial categories for three classes of pollutants: (1) conventional pollutants (total
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Chapter 1—Background
suspended solids, oil and grease, biochemical oxygen demand, fecal coliform, and pH) as
outlined in CWA section 304(a)(4) and 40 CFR 401.16; (2) toxic pollutants (e.g., toxic metals
such as chromium, lead, mercury, nickel, and zinc) as outlined in section 307(a) of the Act, 40
CFR 401.15 and 40 CFR 423, appendix A; and (3) non-conventional pollutants, which are those
pollutants that are not categorized as conventional or toxic (e.g., ammonia-N, formaldehyde, and
phosphorus).
The CWA also authorizes EPA to promulgate nationally applicable pretreatment
standards that restrict pollutant discharges from facilities that discharge wastewater indirectly, by
sending wastewater to publicly owned treatment works (POTWs), as outlined in sections 304(g)
and 307(b), (c) of the CWA. EPA establishes national pretreatment standards for those pollutants
that may pass through, interfere with, or may otherwise be incompatible with POTW operations.
CWA sections 307(b) and (c) and 304(g). The legislative history of the 1977 CWA amendments
explains that pretreatment standards are technology-based and analogous to technology-based
effluent limitations for direct dischargers for the removal of toxic pollutants. As further
explained in the legislative history, the combination of pretreatment and treatment by the POTW
is intended to achieve the level of treatment that would be required if the industrial source were
making a direct discharge.1 As such, in establishing pretreatment standards, EPA's consideration
of pass through for national technology-based categorical pretreatment standards differs from
that described in EPA's General Pretreatment Regulations at 40 CFR 403. For categorical
pretreatment standards, EPA's approach for pass through satisfies two competing objectives set
by Congress: (1) That standards for indirect dischargers be equivalent to standards for direct
dischargers; and (2) that the treatment capability and performance of the POTWs be recognized
and taken into account in regulating the discharge of pollutants from indirect dischargers. CWA
301 (b)( 1)(A)(BPT); and 301(b)(l(E).
EPA develops ELGs that are technology-based regulations for specific categories of
dischargers. EPA bases these regulations on the performance of control and treatment
technologies. The legislative history of CWA section 304(b), which is the heart of the effluent
guidelines program, describes the need to press toward higher levels of control through research
and development of new processes, modifications, replacement of obsolete plants and processes,
and other improvements in technology, taking into account the cost of controls. Congress has
also stated that EPA need not consider water quality impacts on individual water bodies as the
guidelines are developed; see Statement of Senator Muskie (October 4, 1972), reprinted in U.S.
Senate Committee on Public Works, Legislative History of the Water Pollution Control Act
Amendments of 1972, Serial No. 93-1, at 170.
There are standards applicable to direct dischargers (dischargers to surface waters) and
standards applicable to indirect dischargers (dischargers to POTWs). The types of standards
relevant to this rulemaking are summarized below.
1 Conf. Rep. No. 95-830, at 87 (1977), reprinted in U.S. Congress. Senate. Committee on Public Works (1978), A
Legislative History of the CWA of 1977, Serial No. 95-14 at 271 (1978).
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Chapter 1—Background
1.	Best Available Technology Economically Achievable (BAT)
BAT represents the second level of stringency for controlling direct discharge of toxic
and nonconventional pollutants. In general, BAT-based effluent guidelines and new
source performance standards represent the best available economically achievable
performance of facilities in the industrial subcategory or category. Following the
statutory language, EPA considers the technological availability and the economic
achievability in determining what level of control represents BAT. CWA section
301(b)(2)(A). Other statutory factors that EPA considers in assessing BAT are the
cost of achieving BAT effluent reductions, the age of equipment and facilities
involved, the process employed, potential process changes, and non-water quality
environmental impacts, including energy requirements and such other factors as the
Administrator deems appropriate. CWA section 304(b)(2)(B). The Agency retains
considerable discretion in assigning the weight to be accorded these factors.
Weyerhaeuser Co. v. Costle, 590 F.2d 1011, 1045 (D.C. Cir. 1978).
2.	Best Available Demonstrated Control Technology (BADCTVNew Source
Performance Standards (NSPS)
New Source Performance Standards reflect effluent reductions that are achievable
based on the best available demonstrated control technology (BADCT). Owners of
new facilities have the opportunity to install the best and most efficient production
processes and wastewater treatment technologies. As a result, NSPS should represent
the most stringent controls attainable through the application of the BADCT for all
pollutants (that is, conventional, nonconventional, and toxic pollutants). In
establishing NSPS, EPA is directed to take into consideration the cost of achieving
the effluent reduction and any non-water-quality environmental impacts and energy
requirements. CWA section 306(b)(1)(B).
3.	Pretreatment Standards for Existing Sources (PSES)
Pretreatment standards apply to discharges of pollutants to POTWs; Pretreatment
Standards for Existing Sources are designed to prevent the discharge of pollutants to
POTWs that pass through, interfere with, or are otherwise incompatible with the
operation of POTWs, including sludge disposal methods of POTWs. Categorical
pretreatment standards for existing sources are technology-based and are analogous to
BAT effluent limitations guidelines, and thus the Agency typically considers the same
factors in promulgating PSES as it considers in promulgating BAT. See Natural
Resources Defense Council v. EPA, 790 F.2d 289, 292 (3rd Cir. 1986).
4.	Pretreatment Standards for New Sources (PSNS)
Like PSES, Pretreatment Standards for New Sources are designed to prevent the
discharges of pollutants that pass through, interfere with, or are otherwise
incompatible with the operation of POTWs. New indirect dischargers have the
opportunity to incorporate into their facilities the best available demonstrated control
technologies. In establishing pretreatment standards for new sources, the Agency
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Chapter 1—Background
typically considers the same factors in promulgating PSNS as it considers in
promulgating NSPS (BADCT).
5. Best Management Practices (BMPs)
Section 304(e) of the CWA authorizes the Administrator to publish regulations, in
addition to ELGs for certain toxic or hazardous pollutants, "to control plant site
runoff, spillage or leaks, sludge or waste disposal, and drainage from raw material
storage which the Administrator determines are associated with or ancillary to the
industrial manufacturing or treatment process.. .and may contribute significant
amounts of such pollutants to navigable waters." In addition, section 304(g), read in
concert with section 501(a), authorizes EPA to prescribe as wide a range of
pretreatment requirements as the Administrator deems appropriate in order to control
and prevent the discharge into navigable waters either directly or through POTWs any
pollutant which interferes with, passes through, or otherwise is incompatible with
such treatment works. (See also Citizens Coal Council v. U.S. EPA, 447 F3d 879,
895-96 (6th Cir. 2006) (upholding EPA's use of non-numeric effluent limitations and
standards); Water keeper Alliance, Inc. v. U.S. EPA, 399 F.3d 486, 496-97, 502 (2d
Cir. 2005) (EPA use of non-numerical effluent limitations in the form of BMPs are
effluent limitations under the CWA); and Natural Res. Def. Council, Inc. v. EPA, 673
F.2d 400, 403 (D.C. Cir. 1982) ("section 502(11) [of the CWA] defines 'effluent
limitation' as 'any restriction' on the amounts of pollutants discharged, not just a
numerical restriction").
1.2.2 The National Pretreatment Program, 40 CFR 403
The National Pretreatment Program requires industrial dischargers that discharge to
POTWs to comply with pretreatment standards. The General Pretreatment Regulations in 40
CFR 403 establish roles and responsibilities for entities involved in the implementation of
pretreatment standards. This chapter summarizes the roles and responsibilities of Industrial Users
(IUs), Control Authorities, and Approval Authorities. For a detailed description, see the
preamble for the proposed rule (79 FR 63279-63280; October 22, 2014).
An IU is a nondomestic source of indirect discharge into a POTW, and in this rule is the
dental discharger.2 The Control Authority may be the POTW, the state, or EPA, depending on
whether the POTW or the state is approved by EPA to administer the pretreatment program. The
Control Authority is the POTW in cases where the POTW has an approved pretreatment
program. The Control Authority is the state, where the POTW has not been approved to
administer the pretreatment program, but the state has been approved. The Control Authority is
EPA where neither the POTW nor the state have been approved to administer the pretreatment
program. The Approval Authority is the state (Director) in an NPDES authorized state with an
approved pretreatment program; or the EPA regional administrator in a non-NPDES authorized
state or NPDES state without an approved state pretreatment program.
2 EPA notes that the final rule is not determinative of the status of a dental discharger as an IU. In other words,
dental dischargers are IUs in absence of this rule.
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Chapter 1—Background
Typically, an IU is responsible for demonstrating compliance with pretreatment standards
by performing self-monitoring, submitting reports and notifications to its Control Authority, and
maintaining records of activities associated with its discharge to the POTW. The Control
Authority is the regulating authority responsible for implementing and enforcing pretreatment
standards. The General Pretreatment Regulations require certain minimum oversight of IUs by
Control Authorities. The required minimum oversight includes receipt and analysis of reports
and notifications submitted by IUs, random sampling and analyzing effluent from IUs, and
conducting surveillance activities to identify occasional and continuing non-compliance with
pretreatment standards. The Control Authority is also responsible for taking enforcement action
as necessary. For IUs that are designated as Significant Industrial Users (SIUs), Control
Authorities must inspect and sample the SIU effluent annually, review the need for a slug control
plan, and issue a permit or equivalent control mechanism. IUs subject to categorical pretreatment
standards are referred to as Categorical Industrial Users (CIUs). The General Pretreatment
Regulations define SIU to include CIUs. The Approval Authority is responsible for ensuring that
POTWs comply with all applicable pretreatment program requirements. Among other things, the
Approval Authority receives annual pretreatment reports from the Control Authority. These
reports must identify which IUs are CIUs.
1.3 Regulatory History Of The Dental Category
This chapter presents a brief history of activities related to dental category rulemaking.
Chapter 1.3.1 discusses EPA's Detailed Study of the Dental Category. Chapter 1.3.2 discusses
the 2008 memorandum of understanding to reduce mercury discharges. Chapter 1.3.3 describes
the American Dental Association's Best Management Practices and support of a national
rulemaking. Chapter 1.3.4 describes the proposed rule for the dental category, and Chapter 1.3.5
describes existing state and local programs for dental discharges. Chapter 1.3.6 discusses the
2013 Minamata Convention on Mercury.
1.3.1 Detailed Study of the Dental Category
EPA first identified the dental industry for study in its review of the health services
industry in the 2006 Effluent Guidelines Plan (71 FR 76644). EPA selected the industry based in
part on public comments about discharges of mercury from dental offices and dental laboratories.
EPA's study addressed 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?
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Chapter 1—Background
•	What technologies are available (1) as alternatives to wastewater disposal and (2) to
control discharges? How effective are these technologies?
•	What 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?
EPA documented its findings in the August 2008 technical report, Health Services
Industry Detailed Study: Dental Amalgam (EPA-821-R-08-014).
1.3.2	2008 Memorandum of Understanding on Reducing Mercury Discharges
In December 2008, EPA signed a memorandum of understanding (MOU) with the
American Dental Association (ADA) and the National Association of Clean Water Agencies
(NACWA) to establish and monitor the effectiveness of a Voluntary Dental Amalgam Discharge
Reduction Program. The purpose of the MOU is to encourage dental offices to voluntarily install
and properly maintain amalgam separators and recycle the collected amalgam waste. EPA did
not evaluate the effectiveness of the MOU, rather EPA decided that National Pretreatment
Standards for dental facilities would accomplish the goals of the MOU in a more predictable
timeframe.
1.3.3	ADA Best Management Practices and Support for a National Rulemaking
ADA encourages dentists to handle mercury and mercury amalgam in a manner that is
consistent with ADA's Best Management Practices for Amalgam Waste. ADA's BMPs are
designed to reduce the amount of mercury entering the environment. Practices encouraged by
these BMPs include reducing the volume of bulk elemental mercury in dentists' offices,
encouraging dentists to recycle amalgam to the greatest extent possible, preventing mercury from
being disposed of in medical waste bags, and preventing amalgam from entering the wastewater
stream. In 2007, ADA added the use of amalgam separators to their BMPs (ADA, 2007).
In late 2010, ADA's Board of Directors adopted nine principles upon which ADA
supported National Pretreatment Standards for dental facilities (ADA, 2010).
1.3.4	Proposed Rule for the Dental Category
EPA published proposed pretreatment standards for the dental category on October 22,
2014 (79 FR 63258), and took public comment through February 20, 2015. During the public
comment period, EPA received approximately 200 comments submitted to the Federal Data
Management System (FDMS) Docket Number: EPA-HQ-OW-2014-0693. EPA also held a
public hearing on November 10, 2014. Administrative burden was a concern of many of the
commenters on the 2014 proposed rule, particularly from regulatory authorities responsible for
oversight and enforcement of the new standard. Commenters also provided additional
information on amalgam separators (e.g., costs, models, and design) as well as information on
some other approaches to reduce pollutant discharges from dentists. Commenters also offered
ways to improve and/or clarify the proposed pretreatment standards, including the proposed
numerical efficiency and operation and maintenance requirements. See the Effluent Limitations
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Chapter 1—Background
Guidelines and Standards for the Dental Category: EPA 's Response to Public Comments (U.S.
EPA, 2016a) for these comments and EPA's responses.
1.3.5	State and Local Programs
Currently, 12 states (Connecticut, Louisiana3, Maine, Massachusetts, Michigan, New
Hampshire, New Jersey, New Mexico, New York, Rhode Island, Vermont, and Washington)
have mandatory programs to reduce dental mercury discharges. Additionally, at least 18
localities (located in California, Colorado, Ohio, and Wisconsin) similarly have mandatory
dental amalgam reduction pretreatment programs. EPA analyzed readily available information
about these programs and found commonalities (U.S. EPA, 2016b). For example, all require the
use of amalgam separators and most specify associated operating and maintenance requirements.
The majority of these programs also require some type of best management practices, and at least
a one-time compliance report to the regulating authority. See Chapters 6.3 and 6.4 of this
document for more details on these programs.
1.3.6	Minamata Convention on Mercury
On November 6, 2013, the United States joined the Minamata Convention on Mercury, a
new multilateral environmental agreement that addresses specific human activities that are
contributing to widespread mercury pollution. The agreement identifies dental amalgam as a
mercury-added product for which certain measures should be taken. Specifically, the Convention
lists nine measures for phasing down the use of mercury in dental amalgam, including promoting
the use of best environmental practices in dental offices to reduce releases of mercury and
mercury compounds to water and land. Nations that are parties to the Convention are required to
implement at least two of the nine measures to address dental amalgam. This final rule
contributes to the U.S.'s efforts to meet the measures called for in the treaty.
1.4 References
ADA. 2007. Best Management Practices for Amalgam Waste. Updated July 2007. Document
Control Number (DCN) DA00165.
ADA. 2010. ADA Principles to be used to Develop Mandatory Separator Pretreatment Rule.
Washington, DC. October 29. DCN DA00137.
U.S. EPA. 2016a. Effluent Limitations Guidelines and Standards for the Dental Category: EPA 's
Response to Public Comments. Office of Water. Washington, DC. December. DCN
DA00516.
U.S. EPA. 2016b. Interaction of Mandatory State and Local Dental Amalgam Reduction
Programs and the Dental Rule. Memorandum to the Public Record for the Dental
Category Final Rule. Office of Water. Washington, DC. December 6. DCNDA00524.
3 Louisiana state requirements do not explicitly require dental offices to install amalgam separators; dental offices
must follow BMPs recommended by the ADA in 1999. ADA did not add amalgam separators to its list of BMPs
until 2008.
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Chapter 2—Summary and Scope
Chapter 2
Summary and Scope	
The purpose of the dental category final rule is to set technology-based pretreatment
standards to reduce discharges of mercury from dental offices to municipal sewage treatment
plants, known as publicly owned treatment works (POTWs), in the United States. Across the
U.S., 12 states and at least 18 localities have established mandatory programs to reduce
discharges of mercury to POTWs. As a result of these efforts, along with outreach from the
American Dental Association (ADA) to promote voluntary actions to reduce such discharges,
approximately 40 percent of the dental offices subject to this rule have already installed amalgam
separators. Amalgam separators greatly reduce the discharge of mercury-containing amalgam to
POTWs. This rule will ensure that mercury discharges to POTWs are effectively controlled at
dental offices that discharge wastewater to POTWs.
Many studies have been conducted to identify the sources of mercury entering POTWs.
According to the 2002 Mercury Source Control and Pollution Prevention Program Evaluation
prepared for the Association for Metropolitan Sewerage Agencies (AMSA), dental practices are
the main source of mercury discharges to POTWs (Larry Walker Associates, 2002). A study
funded by the ADA published in 2005 estimated that dental offices contributed more than 50
percent of mercury entering POTWs (Vandeven and McGinnis, 2005).4 Mercury is discharged in
the form of waste dental amalgam when dentists remove old amalgam fillings from cavities, and
from excess amalgam waste when a dentist places a new amalgam filling.5
While dental offices are not a major contributor of mercury to the environment generally,
dental offices are the main source of mercury discharges to POTWs. EPA estimates that across
the United States, 5.1 tons of mercury and another 5.3 tons of other metals found in waste dental
amalgam are collectively discharged into POTWs annually (U.S. EPA, 2016a). Mercury entering
POTWs frequently partitions into the sludge, the solid material that remains after wastewater is
treated. Mercury from waste amalgam therefore can make its way into the environment from the
POTW through the incineration, landfilling, or land application of sludge or through surface
water discharge. Once released into the aquatic environment, certain bacteria can change
mercury into methylmercury, a highly toxic form of mercury that bioaccumulates in fish and
shellfish. In the U.S., consumption of fish and shellfish is the main source of methylmercury
exposure to humans. This chapter summarizes the final rule, its application, and
subcategorization.
2.1 Summary Of The Final Rule
The final rule requires dental offices to control the discharge of mercury and other metals
in dental amalgam to POTWs based on the best available technology or best available
demonstrated control technology. Specifically, the requirements are based on the use of amalgam
separators and best management practices recommended by the ADA. The BMPs are (1)
4	EPA performs a similar calculation to estimate current mercury discharges from dental offices. See Chapter 11 of
this document.
5	Other filling types, such as composite fillings, do not contain mercury or other metals.
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Chapter 2—Summary and Scope
prohibiting the discharge of waste (or "scrap") amalgam and (2) prohibition of the use of line
cleaners that are oxidizing or acidic and that have a pH higher than 8 or lower than 6. Amalgam
separators are a practical, affordable and readily available technology for capturing mercury and
other metals before they are discharged into sewers that drain to POTWs. The mercury collected
by these separators can be recycled. This final rule also includes a provision to significantly
reduce and streamline the oversight and reporting requirements in EPA's General Pretreatment
Regulations that would otherwise apply as a result of this rulemaking. EPA expects that
compliance with this final rule would reduce the transfer of metals to POTWs by 10.3 tons per
year, almost half of which (5.1 tons) is mercury (U.S. EPA, 2016a). EPA estimates the annual
cost of the final rule would be $59 to $61 million (U.S. EPA, 2016b).
The final rule requires dental offices to meet a performance standard - BMPs and the use
of an amalgam separator(s) compliant with the 2008 International Organization for
Standardization (ISO) 11143 standard (ISO, 2008), or the American National Standards Institute
(ANSI)/AD A Specification 108 for Amalgam Separators (2009) with Technical Addendum
(2011), (ANSI/AD A, 2009; ANSI/AD A, 2011), or subsequent versions so long as that version
requires amalgam separators to achieve at least a 95% removal efficiency. ISO, a voluntary
standard setting organization, established a standard for measuring amalgam separator efficiency
by evaluating the retention of amalgam solids using specified test procedures in a laboratory
setting. In order to meet the ISO standard, a separator must achieve 95 percent removal or greater
of total solids. The standard also includes requirements for instructions on the use and operation
and maintenance of amalgam separators (see Chapter 7.1.2). The final rule also includes a
provision such that the performance standard can be met with the use of an amalgam removing
technology other than an amalgam separator (equivalent device). EPA included this provision to
incorporate future technologies that achieve comparable removals of pollutants from dental
discharges as amalgam separators but that may not fall under the amalgam separator
classification. Because the rule does not include a numerical limit, the performance standards
also specify certain operation and maintenance requirements for the amalgam separator(s) or
comparable device to ensure they are operated optimally.
In addition to installing one or more amalgam separators compliant with the ISO 11143
standard (or its equivalent) and implementing the required BMPs, the pretreatment standards
specify certain operating and maintenance requirements for the amalgam separator. These
requirements include: documented amalgam separator inspection as specified by the
manufacturer's user manual to ensure the separator is performing properly and to confirm that all
amalgam process wastewater is flowing through the amalgam retaining portion of the separator;
replacement of the amalgam retaining unit of the device in accordance with the manufacturer's
schedule or when the amalgam retaining unit has reached the maximum level, whichever comes
first; repair/replacement as needed; and recycling/disposal of amalgam waste. Reporting
requirements include a One-time Compliance Report.
The final rule allows dental offices to continue to operate amalgam separators installed
prior to publication of this final rule for the equipment lifetime or ten years (whichever comes
first), as long as the dental discharger complies with the other rule requirements including the
specified BMPs, operation and maintenance, reporting, and recordkeeping requirements. Once
the separator needs to be replaced or the ten-year period has ended, whichever comes first, dental
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Chapter 2—Summary and Scope
offices will need to replace the amalgam separator with one that meets the requirements of the
final rule.
Dental offices that do not place amalgam, and do not remove dental amalgam except in
limited emergency or unplanned, unanticipated circumstances are exempt from any further
requirements as long as they certify such in their One-time Compliance Report.
In addition, the rule minimizes the administrative burden on dental offices subject to the
rule, as well as on federal, state, and local regulatory authorities responsible for oversight and
enforcement of the new standard. Administrative burden was a concern of many of the
commenters on the 2014 proposed rule and EPA has greatly reduced that burden through
streamlining the administrative requirements in this final rule.
When EPA establishes categorical pretreatment requirements, it triggers additional
oversight and reporting requirements in EPA's General Pretreatment Regulations. The General
Pretreatment Regulations specify that Control Authorities (which are often the state or POTW)
are responsible for administering and enforcing pretreatment standards, including receiving and
reviewing compliance reports. While other industries subject to categorical pretreatment
standards typically consist of tens to hundreds of facilities, the dental industry consists of
approximately 130,000 offices. Application of the default General Pretreatment Regulation
oversight and reporting requirements to such a large number of facilities would be much more
challenging. Further, dental office discharges differ from other industries for which EPA has
established categorical pretreatment standards. Both the volume of wastewater discharged and
the quantity of pollutants in the discharge on a per facility basis are significantly less than other
industries for which EPA has established categorical pretreatment standards. Accordingly, this
final rule exempts dental offices from the General Pretreatment Regulations' oversight and
reporting requirements associated with categorical pretreatment standards, reflecting EPA's
recognition that the otherwise-applicable regulatory framework for categorical dischargers would
be unlikely to have a significant positive impact on overall compliance with the rule across the
dental industry, while imposing a substantial burden on state and local regulating authorities.
In order to simplify implementation and compliance for the dental offices and the
regulating authorities, the final rule establishes that dental dischargers are not Significant
Industrial Users (SIUs) as defined in 40 CFR 403, and are not Categorical Industrial Users
(CIUs) or "industrial users subject to categorical pretreatment standards" as those terms and
variations are used in the General Pretreatment Regulations, unless designated such by the
Control Authority. While this rule establishes pretreatment standards that require dental offices
to reduce dental amalgam discharges, the rule does not require Control Authorities to implement
the traditional suite of oversight requirements in the General Pretreatment Regulations that
become applicable upon the promulgation of categorical pretreatment standards for an industrial
category. This significantly reduces the reporting requirements for dental dischargers that would
otherwise apply by instead requiring them to demonstrate compliance with the performance
standard and BMPs through a One-Time Compliance Report to their Control Authority. This
regulatory approach also eliminates the additional oversight requirements for Control Authorities
that are typically associated with SIUs, such as permitting and annual inspections of individual
dental offices. It also eliminates additional reporting requirements for the Control Authorities
typically associated with CIUs, such as identification of CIUs in their annual pretreatment
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Chapter 2—Summary and Scope
reports. At the same time, the final rule recognizes the Control Authority's discretionary
authority to treat a dental discharger as an SIU and/or CIU if, in the Control Authority's
judgement, it is necessary.
2.2	Applicability Of The Final Rule
Consistent with the proposal, dental offices that discharge to POTWs are within the scope
of this final pretreatment rule.6'7 EPA identified four dental offices that discharge wastewater
directly to waters of the United States under a National Pollutant Discharge Elimination System
(NPDES) permit (see Chapter 4.3). EPA solicited information in the proposal from the public on
its preliminary finding that, with few exceptions, dental offices do not discharge wastewater
directly to surface waters. EPA did not receive any comments containing data to contradict this
finding. Therefore, EPA is not establishing any requirements for direct wastewater discharges
from dental offices to surface waters at this time.
The final rule applies to wastewater discharges to POTWs from offices where the
practice of dentistry is performed, including large institutions such as dental schools and clinics;
permanent or temporary offices, home offices, and facilities; and including dental offices owned
and operated by federal, state, or local governments including military bases. The final rule does
not apply to wastewater discharges from dental offices where the practice of dentistry consists
exclusively of one or more of the following dental specialties: oral pathology, oral and
maxillofacial radiology, oral and maxillofacial surgery, orthodontics, periodontics, or
prosthodontics. As described in Chapter 4.2, these specialty practices are not expected to engage
in the practice of amalgam placements (restorations) or removals, and are not expected to have
any wastewater discharges containing dental amalgam.
The final rule also does not apply to wastewater discharges to POTWs from mobile units.
EPA proposed to apply the standards to mobile units (typically a specialized mobile self-
contained van, trailer, or equipment from which dentists provide services at multiple locations),
soliciting comments and data pertaining to them (79 FR 63261; October 22, 2014). However,
EPA is not establishing requirements for mobile units at this time because it has insufficient data
to do so. EPA does not have, nor did commenters provide, data on the number, size, operation, or
financial characteristics of mobile units. EPA also has minimal information on wastewater
discharges from mobile units, and/or practices employed to minimize dental amalgam in such
discharges. Therefore, any further evaluation of requirements for mobile units is not possible at
this time, and the final rule requirements do not apply to mobile units.
2.3	SUBCATEGORIZATION
In developing effluent limitations guidelines and pretreatment standards, EPA may divide
an industry category into groupings called subcategories to provide a method for addressing
6	The final rule does not apply to dental discharges to septic systems. This includes dental discharges to septic
systems that are subsequently pumped out and transported to POTWs.
7	The final rule does not apply to dental offices that collect all of their amalgam process wastewater and that transfer
it to a privately owned treatment facility (also referred to as a centralized waste treatment facility or CWT). See §
441.10(e). As a point of clarification, dental offices (or a third party) that truck their amalgam wastewater to a
POTW without first treating that wastewater at a CWT are dental dischargers subject to the rule.
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Chapter 2—Summary and Scope
variations among products, processes, and other factors, which result in distinctly different
effluent characteristics. See Texas Oil & Gas Ass'n. v. US EPA, 161 F.3d 923, 939-40 (5th Cir.
1998). In some cases, effluent limitations or pretreatment standards within a subcategory may be
different based on consideration of these same factors, which are identified in CWA section
304(b)(2)(B). The CWA requires EPA, in developing effluent guidelines and pretreatment
standards, to consider a number of different factors, which are also relevant for
subcategorization. Subcategorization, where warranted, ensures that each subcategory has a
uniform set of ELGs that takes into account technology availability and economic achievability
and other relevant factors unique to that subcategory.
This chapter presents information about factors EPA evaluated to determine whether
subcategorization is warranted in the dental category. Chapter 2.3.1 describes the factors and
Chapter 2.3.2 presents EPA's analyses of the factors.
2.3.1	Subcategorization Factors
The CWA requires EPA to consider a number of different factors when developing ELGs
for a particular industry category (section 304(b)(2)(B), 33 U.S.C. 1314(b)(2)(B)). For best
available control technology economically available (BAT), in addition to the technological
availability and economic achievability, these factors are the age of the equipment and plants, the
process employed, the engineering aspects of the application of various types of control
techniques, process changes, the cost of achieving such effluent reduction, non-water quality
environmental impacts (including energy requirements), and such other factors the Administrator
deems appropriate.
2.3.2	Analysis of Subcategorization Factors
EPA assessed age, location, office size, office type, office configuration, and office type
on the wastewaters generated at dental offices and the availability of technologies to manage
those wastewaters. EPA determined none of these factors warrants different standards. The
following chapters summarize the analyses performed as part of the subcategorization
evaluation.
2.3.2.1 Age of dental office
EPA analyzed the age of dental offices included in the scope of the rule and determined
that the age of the office by itself does not affect the wastewater characteristics or the dental
processes in place. By dental processes, EPA means those procedures at the dental office that
result in process wastewater that contains dental amalgam. For purposes of this analysis, EPA
considers dental offices that conduct placements or restorations of dental amalgam, and/or that
perform removals of dental amalgam, as dental processes. The age of the dental office does not
affect the characteristics of the amalgam process wastewater generated by these dental processes.
EPA reviewed the compliance rates in the states and localities that already have dental amalgam
programs, and did not identify where age of the dental office was a factor in the ability of the
dental office to install and operate an amalgam separator (see Chapter 6). Finally, the age of the
office does not influence whether the BMPs required under this rule (waste amalgam must not be
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Chapter 2—Summary and Scope
discharged to a POTW, and a prohibition on cleaning the dental lines with oxidizing or acidic
cleaners; see 441.40(b)), or whether different BMPs, are warranted.
2.3.2.2	Geographic location
EPA analyzed the geographic location of dental offices included in the scope of the rule.
Dental offices are located in all 50 states (see Chapter 4). EPA determined that the geographic
location by itself does not affect the wastewater characteristics, the processes in place, or the
ability to install and operate the treatment technologies evaluated as part of the final rule. EPA
reviewed the compliance rates in the states and localities that already have dental amalgam
programs, and did not identify where age of the dental office was a factor in the ability of the
dental office to install and operate an amalgam separator (see Chapter 6). EPA found that dental
offices all over the U.S. have installed amalgam separators. The BMPs have been required in
several States and localities with dental amalgam programs, and some dentists have voluntarily
adopted these BMPs as part of their adopting ADA's 9 Principles. Therefore, different
requirements are not warranted.
2.3.2.3	Size of office
EPA analyzed the size of the dental office {i.e., number of chairs) and determined that,
while a dental office with multiple chairs in which amalgam may be placed or removed may
have higher pollutant discharges (mass and volume) than an office with a single chair, the size of
the dental office by itself does not affect the ability to install the treatment technologies
evaluated as part of the final rule. Additionally, while the size of the dental office likely
influences the volume of the amalgam process wastewater, this also does not warrant different
requirements for the following reasons. EPA identified 26 amalgam separator models that meet
the requirements of the final rule. Many of the models are scaled to the size of the office. EPA
also found that very large offices (institutions and military bases) were able to scale up amalgam
separators or have custom amalgam separator units designed for the large application. Some of
these large offices have already adopted the two BMPs identified for the final rule, such as where
the BMPs are already required in States and localities with dental amalgam programs, and some
dentists have voluntarily adopted these BMPs as part of their adopting ADA's 9 Principles. As a
result of its evaluation, EPA concludes that it would not be appropriate to apply different
standards based on size of the dental office. The requirements do not include a size threshold
because the technology(ies) is readily scaled to the size of the dental office.
2.3.3 Office Configuration
EPA has identified dental offices all over the country that perform dental processes, and
has only identified one situation where the process wastewaters may vary: the use of dry pumps
instead of wet vacuums. EPA does not have any data on the frequency of the use of dry pumps,
but does note it is a relatively new practice. EPA finds that this is not a basis for
subcategorization for several reasons. First, if the dental office does not generate any amalgam
process wastewater, the rule would not apply. Second, if the office still generates amalgam
process wastewater due to cuspidors, sinks, collection equipment, washing of dental equipment,
and other office equipment used for amalgam process wastewater, then the rule would apply and
the technology basis for the rule (e.g. amalgam separators) would still be BAT. The use of dry
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Chapter 2—Summary and Scope
pumps does not change the availability or need of the two BMPs for dental amalgam. Therefore,
office configuration does not warrant different requirements.
2.3.3.1 Specialty Type
EPA analyzed the types of dental offices (e.g. specialty practices) and determined that
some dental specialties do not place or remove amalgam and are not expected to have any
wastewater discharges containing dental amalgam. The final rule does not apply to them.
2.4 References
ADA. 2007. Best Management Practices for Amalgam Waste. Updated July 2007. Document
Control Number (DCN) DA00165.
ADA. 2010. ADA Principles to be Used to Develop Mandatory Separator Pretreatment Rule.
Washington, DC. October 29. DCN DA00137.
ANSI/ADA. 2009. Specification 108 for Amalgam Separators (2009). February. DCNDA00514.
ANSI/ADA. 2011. Specification 108 for Amalgam Separators (2009) with Technical Addendum
(2011). January. DCNDA00515.
ISO. 2008. International Organization for Standardization. ISO 11143:2008 Dentistry -
Amalgam Separators Standard. July. DCNDA00138.
Larry Walker Associates. 2002. Mercury Source Control and Pollution Prevention Program
Evaluation. Prepared for Association for Metropolitan Sewerage Agencies. AMSA.
March (Updated July). DCN DA00006.
U.S. EPA. 2016a. Dental Office Cost Calculations. MS Excel® file. Office of Water.
Washington, DC. December. DCN DA00456.
U.S. EPA. 2016b. Economic Analysis for the Dental Amalgam Final Rule. MS Excel® file.
Office of Water. Washington, DC. December. DCN DA00458.
Vandeven, J., and S. McGinnis. 2005. An Assessment of Mercury in the Form of Amalgam in
Dental Wastewater in the United States. Water, Air and Soil Pollution. 164:349-366.
DCN DA00163.
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Chapter 3—Data Collection Activities
Chapter 3
Data Collection Activities	
EPA collected data from a variety of sources for the final dental category rulemaking,
including the Health Services Industry Detailed Study, stakeholder discussions, amalgam
separator manufacturer contacts, and the United States Air Force study on commonly used
amalgam separator systems. This chapter includes a description of each data source; Chapter 4
through Chapter 14 and Chapter 16 of this document include summaries and analyses of the data
collected by EPA. EPA used data from these sources to develop a profile of the industry;
describe dental mercury sources and waste characteristics; describe the environmental impacts of
mercury; identify state and local programs to reduce mercury discharges from dental offices;
characterize the effectiveness and costs of amalgam separators and best management practices
(BMPs); and develop pollutant discharge loadings estimates with and without control
technologies.
3.1	Health Services Industry Detailed Study
EPA first identified the dental industry for study in its 2006 Effluent Guidelines Plan (71
FR 76644) as part of the health services industry. In 2008, EPA published its results from the
detailed study in the technical report, Health Services Industry Detailed Study: Dental Amalgam
(U.S. EPA, 2008). For that report, EPA compiled and summarized information on mercury
discharges from dental offices, BMPs, and amalgam separators. Regarding amalgam separators,
EPA examined their frequency of use, their effectiveness in reducing mercury discharges to
publicly owned treatment works (POTWs), and the capital and annual costs of their installation
and operation. The detailed study report also includes a preliminary industry profile that provides
the number of dental offices, the number of small businesses, discharge information, financial
characteristics of the industry, and a description of the national, state, and local mandatory and
voluntary programs to reduce mercury wastewater discharges from dental offices.
3.2	EPA Strategies To Reduce Mercury Discharges
Before developing the final pretreatment standards, EPA, including its regional offices,
worked closely with states and communities to develop strategies for reducing mercury
discharges, including discharges from dental offices. For example, EPA's Environmental
Technology Verification Program studied amalgam separators to determine effectiveness
(Grubbs, 2003). In addition, EPA regional offices participated 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. In addition, EPA Regions 5 and 8, as
well as EPA Headquarters, participated in the activities listed below to limit mercury discharge
from dental offices.
• Region 5. EPA and Environment Canada, working through the Great Lakes Bi-
national Toxics Strategy, created a Mercury Workgroup that promoted activities to
reduce mercury releases to the Great Lakes Basin. This Workgroup included
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Chapter 3—Data Collection Activities
representative states, environmental organizations, and the Council of Great Lakes
Industries. The Workgroup's review of mercury releases in the Great Lakes area
focused on air emissions. As a result, the Workgroup did not collect trend data on
mercury releases to water. The Workgroup 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 (Cain and Krauel, 2004). The Workgroup did not
quantify reductions in mercury use or reductions in wastewater discharges to POTWs.
•	Region 8. EPA Region 8 developed a draft Mercury Control Strategy to help POTWs
control mercury pollution problems from commercial and smaller industrial users,
including dental offices. This draft Strategy included 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 (U.S. EPA, 2005).
3.3	Literature Review
EPA reviewed literature and collected data on various aspects of the dental industry,
amalgam separators, and mercury discharges, including:
•	Current, relevant technical publications that describe the sources and generation of
mercury wastes at dental offices and the discharge of mercury and other amalgam
filling metals (i.e., copper, silver, tin, and zinc) to POTWs.
•	Current information on possible treatment solutions (i.e., amalgam separators) for
dental offices to reduce mercury in the wastewater and their effectiveness.
•	Current implementation costs for technologies to reduce mercury and other metal
discharges at dental offices.
3.4	Meetings With Stakeholders
EPA participated in several meetings with stakeholders including the Environmental
Council of the States (ECOS), Association of Clean Water Act Administrators (ACWA),
environmental organizations, the American Dental Association (ADA), the National Association
of Clean Water Agencies (NACWA), and various environmental organizations. Chapters 3.4.1
through 3.4.5 summarize information collected during these meetings.8
3.4.1 Environmental Council of the States
EPA participated in several meetings with the Quicksilver Caucus (QSC) of the
Environmental Council of the States. From QSC, EPA collected information on implementing
mandatory amalgam separator programs at the state level, mandatory program language, and
8 EPA documented meetings conducted after publication of the proposed rule in a memorandum to the public record
entitled "Meetings Held Between EPA and Stakeholders after the Proposed Rule" (U.S. EPA, 2016).
3-2
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Chapter 3—Data Collection Activities
compliance reporting and monitoring. QSC also provided EPA with information on efficiency
standards for amalgam separators (ECOS, 2010).
3.4.2	Association of Clean Water Act Administrators
EPA participated in several meetings with the Association of Clean Water Act
Administrators. From ACWA, EPA collected information on existing state dental amalgam
reduction programs including lessons they learned while implementing these programs.
3.4.3	Environmental Organizations
EPA met with a coalition of environmental organizations, led by The Environmental Law
and Policy Center and the National Resources Defense Council (NRDC). In spring 2011, the
coalition submitted a letter listing its suggested BMPs for a dental category rulemaking (Wu,
2011). Meetings between EPA and the coalition of environmental organizations and NRDC
focused on identifying the environmental impacts of dental amalgam discharges and ways to
reduce them.
3.4.4	American Dental Association (ADA)
EPA met with ADA multiple times during this rulemaking. Among other things, ADA
provided data to EPA on their BMPs, the nine principles upon which ADA supports national
pretreatment standards for dental facilities, the number of specialty offices in the industry, the
geographic distribution of dental offices, financial characteristics of the industry, information on
the use of dental amalgam alternatives, and operating characteristics of the industry.
3.4.5	National Association of Clean Water Agencies (NACWA)
EPA met with NACWA multiple times to discuss the impact of pretreatment standards on
POTWs. NACWA provided EPA information on its members' experiences with handling
mercury wastes from dental offices, and implementing pretreatment standards for other
industries. NACWA also provided EPA with information on the burden to permitting authorities
of implementing a dental amalgam pretreatment standard under the existing requirements in Part
403.
3.5 Amalgam Separator Manufacturers (Vendor Contacts)
EPA met with, or participated in calls with, representatives of multiple amalgam
separator manufacturers. The purpose of the meetings was to gather information on the following
issues:
•	How amalgam separators work, limitations of the technology, and system capacity;
•	Treatment technology effectiveness;
•	Installation, operation, and maintenance requirements and equipment lifetime;
•	Capital costs and operating and maintenance costs;
•	Manufacturers' distribution methods;
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Chapter 3—Data Collection Activities
•	Amalgam disposal; and
•	Installation trends.
3.6	Air Force Study
In anticipation of the dental category rulemaking, the United States Air Force Dental
Evaluation and Consultation Service compiled a synopsis of commonly used amalgam separator
systems (U.S. Air Force, 2011). The purpose of this synopsis was to introduce dental clinics to
available amalgam separation system options. The Dental Evaluation and Consultation Service
focused on amalgam separators that are marketed directly to dentists (not necessarily all systems
available). The study includes tables for dentists to select the system that best meets their needs,
as well as highlighting key points, questions, and items for dentists to consider before purchasing
an amalgam separator. The study recommends that clinics actively involve their office managers
and biomedical engineering technicians in the purchasing decision to ensure compatibility of the
amalgam separator with existing office features, proper installation, future maintenance
requirements, and proper disposal of the waste.
For each system, the synopsis describes whether the separator is compliant with the ISO
11143 standard, installation requirements, design capacity, maintenance requirements, recycling
services available from the manufacturer, size, price, and warranty details. EPA incorporated
these data into the technology cost analysis.
3.7	References
ADA. 2010. ADA Principles to be Used to Develop Mandatory Separator Pretreatment Rule.
Washington, DC. October 29. Document Control Number (DCN) DA00137.
Cain, A. and R. Krauel. 2004. U.S. EPA and Environment Canada. Options for Dental Mercury
Reduction Programs: Information for State/Provincial and Local Governments. A Report
of the Binational Toxics Strategy Mercury Workgroup. August 4. DCN DA00132.
ECOS. 2010. Letter to EPA: Implementing a National Vision of Mercury. Washington, DC.
August 19. DCN DA00158.
ERG (Eastern Research Group). 2010. SolmeteX meeting minutes for 15 December 2010.
Chantilly, VA. DCN DA00081.
ERG and Air Techniques. 2011. Notes from telephone conversation between Kimberly Landick,
ERG, and Air Techniques. March 2, 2011. Subject: Amalgam Separator Questions. DCN
DA00060.
ERG and American Dental Accessories. 2011. Email correspondence between Kimberly
Landick, ERG, and American Dental Accessories. February 28, 2011. Subject: Request
for Amalgam Separator Information. DCN DA00061.
ERG and DRNA (Dental Recycling North America). 2011. Notes from telephone conversation
between Kimberly Landick, ERG, and Marc Sussman and Darwin Moreira, DRNA.
March 1, 2011. Subject: Amalgam Separator Questions. DCNDA00062.
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Chapter 3—Data Collection Activities
ERG and Rebec Solutions. 2011. Notes from telephone conversation between Kimberly Landick,
ERG, and Rebec Solutions. March 2, 2011. Subject: Amalgam Separator Questions. DCN
DA00063.
ERG and SolmeteX. 2011. Notes from telephone conversation between Kimberly Landick, ERG,
and SolmeteX, March 2, 2011: Subject Amalgam Separator Questions. DCN DA00064.
Grubbs, G. 2003. Statement of Geoffrey Grubbs, Director, Office of Science and Technology,
United State Environmental Protection Agency, before the Subcommittee on Wellness
and Human Rights of the Committee on Government Reform, United States House of
Representatives. October 8. DCNDA00174.
U.S. Air Force. 2011. Synopsis of Dental Amalgam Separators (Project #10-017). Dental
Evaluation and Consultation Service. February. DCN DA00079.
U.S. EPA. 2005. POTWMercury Control Strategy. EPA Region 8. Denver, CO. May 9. DCN
DA00180.
U.S. EPA. 2008. Health Services Industry Detailed Study: Dental Amalgam. EPA-821-R-08-014.
Office of Water. Washington, DC. August. DCN DA00057.
U.S. EPA. 2011. Information Collection Request: NationalPretreatment Program. OMB
Control No. 2040-0009, EPA ICR No. 0002.14 (Draft). Office of Wastewater
Management. March. DCN DA00144.
U.S. EPA. 2016. Dental Amalgam Pretreatment Standards - Meetings Held Between EPA and
Stakeholders After the Proposed Rule. Memorandum to the Public Record for the Dental
Category Final Rule. Office of Water. Washington, DC. December 14. DCNDA00518.
Wu, Mae. 2011. Comments from Multi-state Mercury Products Campaign, the Environmental
Law and Policy Center, and National Resources Defense Council. April 1. Washington,
DC. DCN DA00136.
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Chapter 4—Profile of Dental Industry
Chapter 4
Profile of Dental Industry
The industry category that would be affected by the dental category rulemaking is Offices
of Dentists (NAICS9 621210), which comprises establishments of health practitioners primarily
engaged in the independent practice of general or specialized dentistry or dental surgery. These
practitioners operate individual or group practices in their own offices or in the offices of others,
such as hospitals or Health Management Organization (HMO) medical centers. They can provide
either comprehensive preventive, cosmetic, or emergency care, or specialize in a single field of
dentistry. EPA used data from the U.S. Census, EPA's Toxic Release Inventory (TRI), and
discharge monitoring reports (DMR)10 to estimate the number of dental offices and to understand
how they discharge their wastewater.
TRI and the U.S. Census classify industries by NAICS codes, while DMR classifies
industries by Standard Industrial Classification (SIC) codes. There is a 100 percent correlation
between NAICS and SIC codes for the dental industry. Dental offices fall under NAICS 621210
(SIC Code 8021), 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 health management organization (HMO) medical centers. They can provide
either comprehensive preventive, cosmetic, or emergency care, or specialize in a single
field of dentistry."
4.1 Number Of Dental Offices
EPA's main source of information for the number of dental offices is the 2012 Economic
Census, which reported that there were 133,221 U.S. dental offices. Table 4-1 provides a
comprehensive listing of the dental offices by state for NAICS 621210 (Dental Offices). The
number of dental offices has increased approximately one percent each year. Table 4-2 shows the
industry changes over time. The financial profile of the dental industry is included in Chapter 10
of this document.
In addition to dental offices, dentistry can be performed at larger institutional dental
offices (e.g., clinics or dental schools). These dental offices are not included in the 2012
Economic Census data. EPA estimates that in addition to the 133,221 dental offices identified
from the Economic Census, there are 350 military clinics and 65 dental schools (U.S. EPA,
2016a).
9	North American Industry Classification System.
10	The DMR data are from EPA's Integrated Compliance Information System-National Pollutant Discharge
Elimination System (NPDES) database.
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Chapter 4—Profile of Dental Industry
Table 4-1. Number of Dental Offices by State (2012)
State
NAICS 621210: Dental Offices
Alabama
1,492
Alaska
311
Arizona
2,695
Arkansas
1,000
California
21,157
Colorado
2,791
Connecticut
1,780
Delaware
251
District of Columbia
334
Florida
7,770
Georgia
3,445
Hawaii
658
Idaho
784
Illinois
6,012
Indiana
2,376
Iowa
1,058
Kansas
1,068
Kentucky
1,567
Louisiana
1,599
Maine
479
Maryland
2,638
Massachusetts
3,196
Michigan
4,282
Minnesota
1,991
Mississippi
884
Missouri
2,113
Montana
452
Nebraska
804
Nevada
1,096
New Hampshire
611
New Jersey
4,792
New Mexico
691
New York
9,264
North Carolina
3,154
North Dakota
267
Ohio
4,323
Oklahoma
1,391
Oregon
1,934
Pennsylvania
5,200
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Chapter 4—Profile of Dental Industry
Table 4-1. Number of Dental Offices by State (2012)
State
NAICS 621210: Dental Offices
Rhode Island
395
South Carolina
1,539
South Dakota
299
Tennessee
2,204
Texas
9,446
Utah
1,664
Vermont
260
Virginia
3,243
Washington
3,558
West Virginia
552
Wisconsin
2,119
Wyoming
232
Total U.S.
133,221
Source: U.S. Census Bureau, 2012.
Table 4-2. Growth in Number of Dental Offices (1997 to 2012)
NAICS Code
SIC Code
Number of
Offices in
1997
Number of
Offices in
2002
Number of
Offices in
2005
Number of
Offices in
2007
Number of
Offices in
2012
621210:
Offices of
Dentists
8021: Offices
and Clinics of
Dentists
114,178
118,305
122,918
127,057
133,221
Sources: Johnston 2005; U.S. Census Bureau, 2007a and 2007b; U.S. Census Bureau, 2012.
4.2 Specialty Practices At Dental Offices
Dentistry includes the evaluation, diagnosis, prevention, and treatment of diseases,
disorders, and conditions of the oral cavity, maxillofacial area, and the adjacent and associated
structures. Services provided include nonsurgical and surgical or related procedures. Most dental
offices fall under the category of general dentistry. In addition to a general practice, dentists may
specialize in other areas. Dentists who typically place or remove dental amalgam are either
general dentists or specialize in pediatric dentistry. The nine areas of dentistry that EPA
specifically evaluated for inclusion within the pretreatment standards include the following
(ADA, 2011):
•	General dentistry—practice provides primary and comprehensive preventive and
therapeutic oral health care for patients.
•	Pediatric dentistry—practice provides general dentistry services (i.e., primary and
comprehensive preventive and therapeutic oral health care) for age-specific group
(i.e., infants and children through adolescence).
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Chapter 4—Profile of Dental Industry
•	Endodontics—practice encompasses the basic and clinical sciences including biology
of the normal teeth (pulp) and diseases/injuries of the teeth and associated condition
of the root.
•	Oral and maxillofacial pathology—practice focuses on diseases affecting the oral and
maxillofacial regions.
•	Oral and maxillofacial radiology—discipline concerned with the production and
interpretation of images and data produced for the diagnosis and management of
diseases, disorders, and conditions of the oral and maxillofacial region.
•	Oral and maxillofacial surgery—specialty includes the diagnosis, surgical and
adjunctive treatment of diseases, injuries, and defects involving both the functional
and esthetic aspects of the hard and soft tissues of the oral and maxillofacial region.
•	Orthodontics and dentofacial orthopedics—specialty includes the diagnosis,
prevention, interception, and correction of malocclusion (i.e., misalignment of teeth),
as well as neuromuscular and skeletal abnormalities of orofacial structures.
•	Periodontics—practice focuses on diseases of the supporting and surrounding tissues
of the teeth or their substitutes.
•	Prosthodontics—specialty service for patients with clinical conditions associated with
missing or deficient teeth and/or oral and maxillofacial tissues using biocompatible
substitutes.
Of the specialty practices listed above (i.e., all practices except general and pediatric
dentistry), EPA expects only endodontic and prosthodontic offices to place or remove amalgam.
EPA is not including wastewater discharges from dental offices where the practice does not
typically place or remove dental amalgam.
ADA compiled data on the supply of dentists from 2001 through 2015 by type practice,
including general practice and nine specialty practices (ADA, 2016). Of the 195,722 dentists
practicing in 2015, 154,719 dentists are in general practices (79 percent) and 41,003 dentists are
in specialty practices (21 percent). There are 16,163 dental offices that practice pediatric
dentistry, endodontics, or prosthodontics (39 percent of specialty practices). Therefore, EPA
estimates that over 116,000 dental offices11 would be subject to the final dental category
rulemaking.
4.3 Discharge Information
EPA currently lacks a central database on reported discharges from dental offices. Often,
EPA looks to information in TRI and DMR databases to gather information on industrial
dischargers. However, no dental office (NAICS Code 621210) reports to TRI as they are not
required to do so. Based on information contained in EPA's Envirofacts PCS-Integrated
Compliance Information System12 database, EPA identified four dental offices that have National
11	In addition to dental offices, large, institutional offices are also subject to the final rule. EPA estimates there are
415 of these large, institutional offices.
12	Permit Compliance System- Integrated Compliance Information System.
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Chapter 4—Profile of Dental Industry
Pollutant Discharge Elimination System (NPDES) permits in 2016. The dental offices were
classified as minor dischargers. Of these, none of the offices reported discharge information in
the database. Table 4-3 lists the dental offices with NPDES permits in the PCS-Integrated
Compliance Information System database.
Table 4-3. Dental Offices with NPDES Permits in Integrated Compliance Information
System -NPDES3
NAICS (SIC)
NPDESID
Office Name
Location
621210: Dental Offices
(8021: Dental Offices)
COR03N267
Perfect Teeth Commerce City
Commerce City, CO
COR03Q060
Coal Creek Oral Surgery
Lafayette, CO
MDG766085
Magothy Marinab
Annapolis, MD
MI0053902
University of Michigan13
Ann Arbor, MI
Source: U.S. EPA, 2016b.
a - The Integrated Compliance Information System-NPDES database includes two additional NPDES permits in
Michigan but not for dental offices (two localities); EPA assumed the dental offices in the localities are discharging
indirectly to POTWs. The database also identified 17 NPDES permits in Louisiana; EPA confirmed that Louisiana
used the general permit identification numbers to identify dental offices that use an amalgam separator. EPA
confirmed the 17 facilities are indirect dischargers (U.S. EPA, 2016c).
b - Dental offices may be included in combined discharges to surface waters.
The lack of discharge information is consistent with EPA's 2007 and 2005 reviews of the
dental industry. These reviews indicate that nearly all dental offices are indirect dischargers
(Johnston, 2005; U.S. EPA, 2008).
4.4 References
ADA. 2011. Definitions of Special Areas of Dental Practice, http ://www.ada.org/25 5 5.aspx#top.
DCN DA00044.
ADA. 2016. Supply of Dentists in the U.S by Practice, Research, or Administration Area: 2001 -
2015. MS Excel® file. DCN DA00460.
Johnston, C. 2005. U.S. EPA. Industry Sectors Being Evaluated Under Proposed "Health
Services Industry " Category. Memorandum to the Public Record for the 2006 Effluent
Guidelines Program Plan. 4 August. DCN DA00172.
U.S. Census Bureau. 2007a. Sector 62: Health Care and Social Assistance: Geographic Area
Series: Summary Statistics: 2007. 2007 Economic Census. Subject Series. EC0762A1.
DCN DA00046.
U.S. Census Bureau. 2007b. Sector 31: Manufacturing: Industry Series: Detailed Statistics by
Industry for the United States: 2007. 2007 Economic Census. Subject Series. EC0731I1.
DCN DA00047.
U.S. Census Bureau. 2012. 2012 Economic Census: Office of Dentists (NAICS 621210). DCN
DA00469.
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Chapter 4—Profile of Dental Industry
U.S. EPA. 2008. Health Services Industry Detailed Study: Dental Amalgam. EPA-821-R-08-014.
Washington, DC. August. DCN DA00057.
U.S. EPA. 2016a. Memo on Institutional Facilities. Memorandum to the Public Record for the
Dental Category Final Rule. Office of Water. Washington, DC. December 5. DCN
DA00511.
U.S. EPA. 2016b. Envirofacts PCS-ISIS (website). Data available at:
https://www3.epa.gov/enviro/facts/pcs-icis/search.html. Accessed September 2016. DCN
DA00483.
U.S. EPA. 2016c. Identifying Dental Direct Dischargers in Louisiana. Memorandum to the
Public Record for the Dental Category Final Rule. Office of Water. Washington, DC.
November 29. DCN DA00510.
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Chapter 5—Dental Amalgam Waste, Pollutants of Concern, and POTW Pass Through
Chapter 5
Dental Amalgam Waste, Pollutants of Concern, and POTW
Pass Through	
This chapter discusses the sources of amalgam waste from dental offices and describes a
typical office configuration. This chapter also focuses on the pollutants of concern for amalgam
waste and the pass through of these pollutants at publicly owned treatment works (POTWs).
5.1 Sources Of Dental Amalgam In Wastewater From Dental Offices
Dental amalgam used in dental offices consists of approximately 49 percent mercury, by
weight, mixed with a powder of silver, tin, copper, and zinc, and small amounts of indium or
palladium. The liquid mercury and metal powder mixture are often supplied in capsules, in
which they are kept separate until the dentist is ready to complete a restoration. When the dentist
triturates (mixes) the mercury and powder, the mercury dissolves the powdered metals and a
series of intermetallic compounds (e.g., Ag3Sn, Ag2Hg3, SnxHg) are formed (Vandewall, 2007).
Amalgam discharges generally occur in the course of two dental office activities. The
first activity is patient treatment, such as during the placement or removal of a filling. When
filling a cavity, dentists overfill the tooth and then carve the filling into proper shape (Columbia
University, 2005). The dentist then typically rinses the excess amalgam into a chair-side drain
with a cuspidor or suctions it from the patient's mouth with a vacuum system. Dentists also
remove old cavity restorations that are worn or damaged. Removed restorations are also rinsed
into the chair-side drain or suctioned out of the patient's mouth. The second activity where
amalgam discharges occur is not directly involved with the placement or removal of dental
amalgam. Preparation of dental amalgam, disposing of excess amalgam, and flushing vacuum
lines with corrosive chemicals also can result in discharge of dental amalgam mercury.
Dental amalgam traditionally has been used as a restorative material for cavities because
the malleability of newly mixed amalgam makes it easy to place into cavities and because of its
durability over time. The use of dental amalgam has decreased steadily since the late 1970s as
alternative materials such as composite resins and glass ionomers have become more widely
available. Some dental offices have also elected not to remove amalgam restorations.
Estimates show that placements of dental amalgam have decreased on average by about 2
to 3 percent per year (74 FR 38686). However, even with decreasing placements of dental
amalgam, removals of dental amalgam already placed in patient's mouths will continue into the
foreseeable future. Available data shows removals comprise the largest portion of dental
amalgam discharges from dental offices. This is further described in Chapter 11.
Another source of dental amalgam in wastewater is from the flushing of dental unit
wastewater lines and wastewater plumbing. Dental offices use disinfectants or line cleaners to
reduce odors, remove solid waste particles and biofilms in the lines, and to maintain low
microbial counts in dental unit water. When dental offices use oxidizing or acidic lines cleaners,
such as bleach, chlorine, iodine and peroxide, mercury can be released from the amalgam waste
that has collected in the system (e.g., wastewater and plumbing lines, chair-side traps, vacuum
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Chapter 5—Dental Amalgam Waste, Pollutants of Concern, and POTW Pass Through
pump filters, and amalgam separators) (Batchu et. al., 2006). Oxidizing line cleaners can also
solubilize elemental mercury bound to the amalgam.
5.2 Deni al Office Configuration
The typical plumbing configuration in a dental office consists of a chair-side trap for each
chair and a central vacuum pump with a vacuum pump filter. A cuspidor may or may not be part
of the plumbing configuration at a dental office. The chair-side traps and vacuum pump filters
remove approximately 78 percent of dental amalgam particles from the wastewater stream
(Vandeven and McGinnis, 2005). Offices with multiple chairs typically share the vacuum lines
between chairs. Accordingly, this limits the locations for installation of control and treatment
technologies. Dental offices may install controls at or near each individual chair; within the
vacuum system piping; at a central location upstream of the vacuum pump; or at the exit of the
air/water separator portion of the vacuum system. Figure 5-1 di splays a typical plumbing
configuration in a dental office and includes an amalgam separator installed at a central location
upstream of the vacuum pump. In this configuration, wastewater in the vacuum line goes through
the amalgam separator, and the cuspidor drain is connected to the central vacuum line (Dube,
2010; McManus and Fan, 2003).
Cuspidor
Cliau-side trap Cuspidoi
Chair-side trap
Dental
Operatories'
\ acuum
PumpFiltei
Air Exhaust
Basement
or Utility
Closet
Amalgam
Separator
= Vacuum line
= Wastewater to
sewer
= Air Exhaust
Vacuum
Pump c
Wastewater to
sewer
a (Flight Dental Systems, 2006)
b (Dental Equipment & Repair, 2008)
c (Dental Classifieds, 2011)
Sources: Dube, 2010; McManus and Fan. 2003.
Figure 5-1. Typical Amalgam Separator Plumbing Configuration in a Dental Office
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Chapter 5—Dental Amalgam Waste, Pollutants of Concern, and POTW Pass Through
Physical office and building configurations may pose additional installation
considerations, such as space limitations in the absence of a basement, electrical power
accessibility, and existing sewer connections. In the case of very large offices, clinics, and
medical buildings, it may be possible to combine waste flows between offices to share or reduce
costs.
5.3 Pollutants Of Concern And Pass Through
CWA section 301(b) directs EPA to eliminate the discharge of all pollutants where it is
technologically available and economically achievable (after a consideration of the factors
specified in section 304(b) of the Act). The first step in such an analysis is typically to identify
Pollutants of Concern (POCs) - or the pollutants potentially regulated in the effluent guideline.
For this rule, EPA identified the primary metals in dental amalgam as pollutants of concern:
mercury, silver, tin, copper, and zinc.
5.3.1 POTW Pass Through Analysis
Generally, in determining whether pollutants pass through a POTW when considering the
establishment of categorical pretreatment standards, EPA compares the median percentage of the
pollutant removed by POTWs achieving secondary treatment with the median percentage of the
pollutant removed by facilities meeting BAT effluent limitations. EPA deems a pollutant to pass
through a POTW when the percentage removed by POTWs is less than the percentage removed
by direct dischargers complying with BPT13/BAT effluent limitations. In this manner, EPA can
ensure that the combined treatment at indirect discharging facilities and POTWs is at least
equivalent to that obtained through treatment by a direct discharger, while also considering the
treatment capability of the POTW. In the case of the final rule for the dental category, where
EPA is only developing pretreatment standards, EPA compares the POTW removals with
removals achieved by indirect dischargers using the technology that otherwise satisfies the BAT
factors.
Historically, EPA's primary source of POTW removal data is its 1982 "Fate of Priority
Pollutants in Publicly Owned Treatment Works" (also known as the 50 POTW Study). This well
documented study presents data on the performance of 50 POTWs achieving secondary
treatment in removing toxic pollutants. As part of the development of ELGs for the Centralized
Waste Treatment (CWT) Industry promulgated in December 2000, EPA developed and
documented a methodology, including data editing criteria, to calculate POTW percent removals
for various toxic pollutants from the data collected in the study (U.S. EPA, 2000). EPA provided
the opportunity for public comment on the percent removal methodology and the resulting
percent removals in the CWT proposal. EPA similarly used and presented this methodology and
data in subsequent ELG proposals and final rules.
As part of this methodology, EPA edited the data to minimize the possibility that low
POTW removals might simply reflect low influent concentrations instead of treatment
effectiveness:
13 Best Practicable Control Technology Currently Available.
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Chapter 5—Dental Amalgam Waste, Pollutants of Concern, and POTW Pass Through
1.	Substitute the standardized pollutant-specific minimum analytical detection limit
(ML) for values reported as "not detected," "trace," "less than (followed by a
number)," or a number less than the ML.
2.	Retain pollutant influent and corresponding effluent values if the average pollutant
influent level is greater than or equal to 10 times the pollutant ML.
3.	If none of the average pollutant influent concentrations are at least 10 times the
pollutant ML, then retain average influent values greater than or equal to two times
the pollutant ML along with corresponding effluent data.
For each POTW that had data pairs that passed the editing criteria, EPA calculated its
percent removal for each pollutant based on its average influent and average effluent values. The
national POTW percent removal for each pollutant is the median value of all the POTW
pollutant-specific percent removals.
The 50 POTW Study measured pollutant reductions on the basis of total metals. Total
metals include particulate (suspended) and dissolved (soluble) forms of the metal. While
mercury is present in dental amalgam in both the particulate and dissolved form, the vast
majority (>99.6 percent) is particulate (Stone, 2004). While EPA does not have information on
the distribution of the other metals present in dental amalgam, EPA reasonably assumed the
same distribution for the other metals. Because secondary treatment technologies are not
designed to remove dissolved metals, for purposes of this pass-through analysis, EPA assumes
dissolved metals are not removed by POTWs and that the percent reductions for POTWs
represent particulate (Metcalf & Eddy, 2003). Therefore, EPA used the 50 POTW Study percent
removals to represent particulate14 reductions. For the pollutants of concern, POTWs remove the
following percentages from wastewater prior to discharge (U.S. EPA, 1982):
•	90.2 percent of mercury
•	88.3 percent of silver;
•	42.6 percent of tin;
•	84.2 percent of copper; and
•	79.1 percent of zinc.
EPA received data from targeted studies performed by NACWA that indicate a POTW
can remove as much as 95 percent of total mercury (NACWA, 2007) and POTW performance
data from a nationwide voluntary survey of NACWA members with a calculated three-year
average removal efficiency15 of 94 percent (U.S. EPA, 2016a). However, EPA finds these data
14	Particulates are specified here because data shows a small portion of mercury from dental amalgam is in dissolved
form. This introduces a small but negligible margin of error because: the vast majority (>99.6 percent) of total
mercury is particulate mercury; amalgam separators are not typically designed for removal of dissolved mercury; the
2008 ISO 11143 testing protocol is for dental amalgam solids removal; and because secondary treatment at POTWs
are not designed for dissolved mercury removal. However, to be more succinct, EPA refers to mercury removal by
amalgam separators as removal of particulate mercury.
15	EPA notes that in conducting its pass through analysis, EPA calculates and compares median percent removals
rather than average percent removals.
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Chapter 5—Dental Amalgam Waste, Pollutants of Concern, and POTW Pass Through
are not appropriate for replacing the 50 POTW data for a number of reasons; see Chapter 16 for
further discussion of these data. Consequently, EPA found that data from the 50 POTW Study
continues to represent the best data available to determine the percent removed nationwide by
well operated POTWs employing secondary treatment.
To determine the median percent removal of mercury and other pollutants of concern by
amalgam separators, EPA collected information on the efficacy of existing separators. EPA
excluded those separators that did not meet the 2008 ISO 11143 standards. Amalgam separator
efficiencies are measured as a percent reduction in mass, reflecting the dental amalgam
particulates collected by the device. EPA determined the median percent removal of particulates
by amalgam separators that meet the 2008 ISO 11143 standards is 99.3 percent (U.S. EPA,
2016b).
As discussed above, for the final rule, EPA maintained a POTW removal rate of 90.2
percent of total mercury for its nationwide pass-through analysis. The median percent removal of
particulates by amalgam separators that meet the 2008 ISO standards is 99.3 percent. Because
the median percent removal of amalgam separators exceeds the median percent removal of well-
operated POTWs employing secondary treatment for mercury, EPA determines that mercury
passes through. (Even if EPA were to use the data as reported by NACWA, the 94 percent
removal efficiency is still less than the 99.3 percent removal efficiency of amalgam separators
compliant with the 2008 ISO 11143 standards.) Similarly, because the median percent removal
of amalgam separators exceeds the median percent removal of well-operated POTWs employing
secondary treatment for the other pollutants of concern, EPA determines that these metals
contained in dental amalgam (i.e., silver, tin, copper, and zinc), also pass through.
5.4 References
Batchu, H., H.N. Chou, D. Rakowski, and P.L. Fan. 2006. The Effect of Disinfectants and Line
Cleaners on the Release of Mercury from Amalgam. Journal of the American Dental
Association, 137(10): 1419-1425. Document Control Number (DCN) DA00215.
Columbia University. 2005. October 19, 2005. Class II Amalgam Restoration.
http://www.columbia.edu/itc/hs/dental/ operative/amalgam.html. DCN DA00200
Dental Classifieds. 2011. New Tech West Dental Vacuum 2 user Pump with Recycler.
http://www.dentalclassifieds.com/listing.asp?LID=l 1184&catID=46. DCN DA00053.
Dental Equipment & Repair. 2008. Amalgam Separator.
http://dentalequipmentandrepair.com/id 122.html. DCN DA00054.
Dube, Al. 2010. SolmeteX. 12th Annual EPA New England Pretreatment Coordinators
Workshop, Amalgam Separator Inspection. October 13-14. DCNDA00056.
Flight Dental Systems. 2006. Operatory Systems > A3 Operatory System. DCNDA00065.
McManus, K.R., and P.L. Fan. 2003. Purchasing, Installing and Operating Dental Amalgam
Separators. Journal of the American Dental Association, 134:1054-1065. DCN
DA00162.
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Chapter 5—Dental Amalgam Waste, Pollutants of Concern, and POTW Pass Through
Metcalf & Eddy. 2003. Wastewater Engineering Treatment and Reuse, Fourth Edition. McGraw
Hill. DCN DA00563.
NACWA (National Association of Clean Water Agencies). 2007. An Examination of Mercury
Levels at Clean Water Agencies 2003-2006. December 18. DCN DA00108.
Stone, M.E. 2004. The Effect of Amalgam Separators on Mercury Loading to Wastewater
Treatment Plants. Journal of the California Dental Association, 32(7):593-600. DCN
DA00018.
U.S. EPA. 1982. Fate of Priority Pollutants in Publicly Owned Treatment Works. EPA-440-1-
82-303. Office of Water. Washington, DC. September. DCNDA00244.
U.S. EPA. 2000. Development Document for Effluent Limitations Guidelines and Standards for
the Centralized Waste Treatment Industry - Final. EPA 821-R-00-020. Office of Water.
Washington, DC. August. DCN DA00520.
U.S. EPA. 2016a. Memorandum to the Record on the Statistical Review and Data Editing of
POTW Data from NACWA. Office of Water. Washington, DC. DCN DA00463.
U.S. EPA. 2016b. Amalgam Separator Cost Breakdown by Chair Size. MS Excel® file. Office
of Water. Washington, DC. December. DCN DA00454.
Vandeven, J., and S. McGinnis. 2005. An Assessment of Mercury in the Form of Amalgam in
Dental Wastewater in the United States. Water, Air and Soil Pollution, 164:349-366.
DCN DA00163.
Vandewall, K.S. 2007. Dental Amalgam. USAF Dental Evaluation and Consultation Services.
September. DCN DA00199.
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Chapter 6—Current National, State, and Local Dental Mercury Reduction Programs
Chapter 6
Current National, State, and Local Dental Mercury
Reduction Programs	
National, state, and local programs have reduced discharges of dental mercury to publicly
owned treatment works (POTWs). National programs include the 2008 Memorandum of
Understanding (MOU) between EPA, the American Dental Association (ADA), and the National
Association of Clean Water Agencies (NACWA) (see Chapter 1.3.2) and best management
practices (BMP) guidance from ADA. Currently, 12 states have established mandatory state-
wide programs to control mercury discharges from dental offices. EPA also reviewed
requirements for 18 local mandatory programs in four additional states. This chapter includes the
following subchapters:
•	Chapter 6.1 discusses national dental amalgam requirements.
•	Chapter 6.2 describes national dental amalgam guidance.
•	Chapter 6.3 summarizes state programs.
•	Chapter 6.4 summarizes local programs.
•	Chapter 6.5 presents voluntary programs.
6.1 National Dental Amalgam Requirements
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 wastewater discharges to POTWs. EPA
regulates the disposal of mercury-containing waste under the Resource Conservation and
Recovery Act (RCRA).
6.1.1 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.16'17 A waste is defined as a characteristic hazardous waste
if it exhibits the toxicity characteristics for mercury, defined as containing enough mercury to
exceed the regulatory threshold of 0.2 milligrams per liter (mg/L), or 0.2 parts per million (ppm),
when subjected to a 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 regulatory requirements differ
depending upon the total amount of hazardous waste a site generates per month. Most dental
practices generate less than 100 kilograms of non-acute hazardous waste per month and less than
16	There are also some source-specific hazardous wastes that are listed due to mercury; however, dental amalgam
wastes are not listed in the hazardous-waste regulations at 40 CFR 261 Subpart D.
17	Elemental mercury found in dental amalgam is a non-acute hazardous waste. Unused elemental mercury being
discarded would be a listed hazardous waste (waste code U151).
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Chapter 6—Current National, State, and Local Dental Mercury Reduction Programs
1 kilogram of acute hazardous waste per month. Such facilities are therefore classified as "Very
Small Quantity Generators" (VSQGs). VSQGs are not subject to most of the RCRA hazardous
waste requirements, but do have restrictions on their disposal (see 40 CFR 262.14). Most states
implement the RCRA program, and many states have additional requirements for the handling of
mercury, including waste dental amalgam. Therefore, the requirements for handling mercury
waste and dental amalgam waste can vary from state to state. EPA's compliance assistance
center website provides links to state hazardous waste requirements
(https://www.epa.gov/compliance/compliance-assistance-centers). Chapter 6.3 provides details
on mandatory state programs for managing dental amalgam waste.
The Agency encourages the legitimate recycling of hazardous wastes when possible.
Scrap dental amalgam contains both mercury and silver, and recovery of its silver value may be
cost effective. Also, for generators of more than 100 kg hazardous waste per month, scrap
amalgam can be recycled under reduced requirements by following the precious metal recovery
regulations at 40 CFR 266.70. Further, waste from amalgam separators may be considered
sludge under RCRA. Characteristic sludges are not solid or hazardous wastes when legitimately
reclaimed. Likewise, any unused amalgam would be considered a commercial chemical product
(CCP). CCPs also are not solid or hazardous wastes when legitimately reclaimed.
6.1.2	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 or discharge of spent
amalgam (OSHA, 1997).
6.1.3	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 and the
Centers for Disease Control focus on the health risks of amalgams to dentists, dental workers,
and patients, rather than on the disposal or discharge of spent amalgam (FDA, 2008).
6.2 National Dental Amalgam Guidance
The ADA has developed several programs to reduce dental mercury being discharged
from dental offices. Programs include development of best management practices, a list of nine
principles, and creation of an amalgam recovery program.
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Chapter 6—Current National, State, and Local Dental Mercury Reduction Programs
6.2.1 ADA Best Management Practices
The most widely known national voluntary program for reducing dental amalgam
releases to the environment is the "Best Management Practices for Amalgam Waste" developed
and approved by the ADA Board of Trustees. ADA first published this program in January 2003
and updated it in 2007 to include amalgam separators. The ADA-deftned BMPs are recognized
as the industry standard; 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 proper
management, recycling, and disposal of amalgam waste. ADA also provides advice for
successful integration of BMPs into dental offices, a directory of national dental amalgam 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). Table 6-1 lists the ADA BMPs for dental amalgam.
Table 6-1. ADA BMPs for Dental Amalgam
Focus
Best Management Practice
General
Recycle amalgam waste 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 as utility gloves, masks, and protective eyewear when handling it.
Check with city, county, or local waste authorities for an amalgam waste recycler and for any special
requirements that may exist in the area for collecting, storing, and transporting amalgam waste.
Store amalgam waste in a covered plastic container labeled "Amalgam for Recycling" or as directed
by the recycler.
Store different types of amalgam (e.g., contact and non-contact) in separate containers for recycling.
Amalgam
capsules
Do not use bulk elemental mercury, also referred to as liquid or raw mercury.
Use pre-capsulated alloys and stock a variety of capsule sizes.
Recycle used disposable amalgam capsules.
Do not put disposable amalgam capsules in biohazard containers, infectious waste containers (red
bags), or regular garbage.
Non-
contact
amalgam
Salvage, store, and recycle non-contact amalgam.
Do not put non-contact amalgam waste in biohazard containers, infectious waste containers (red
bags), or regular garbage.
Place unused non-contact amalgam in a silver or gray storage container or a storage container with a
silver or gray label (keep containers sealed at all times).
Contact
amalgam
Salvage amalgam pieces from restorations after removal and recycle the amalgam waste.
Do not put contact amalgam waste in biohazard containers, infectious waste containers (red bags), or
regular garbage.
Recycle teeth that contain amalgam restorations after confirming with the recycler that they will
accept extracted teeth with amalgam restorations.
Do not dispose of extracted teeth that contain amalgam restorations in biohazard containers,
infectious 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).
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Chapter 6—Current National, State, and Local Dental Mercury Reduction Programs
Table 6-1. ADA BMPs for Dental Amalgam
Focus
Best Management Practice
Chair-side
traps
Use chair-side traps to retain amalgam and recycle the content.
Do not rinse chair-side traps containing amalgam over drains or sinks.
Disposable traps from dental units dedicated strictly to hygiene may be placed in with the regular
garbage.
Place disposable chair-side traps and the contents of reusable chair-side traps in a silver or gray
storage container or a storage container with a silver or gray label (keep containers sealed at all
times).
Amalgam
separators
Select an amalgam separator that complies with ISO 11143.
Follow the manufacturer's recommendations for maintenance and recycling procedures.
Other
amalgam
collection
devices
Recycle contents retained by the vacuum pump filter, amalgam separator, or other amalgam
collection device that may be used, if they contain amalgam.
Do not rinse vacuum pump filters containing amalgam, amalgam separator canisters, or other
amalgam collection devices that may be used over drains or sinks.
Change the filter according to the manufacturer's recommended schedule.
Place disposable vacuum pump filters and the contents of reusable vacuum pump filters in a silver or
gray storage container or a storage container with silver or gray label (keep containers sealed at all
times).
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.
6.2.2 ADA Nine Principles
In 2010, ADA adopted a resolution that endorses a mandatory national pretreatment
standard for dental office wastewater if it is consistent with nine principles laid out in the
resolution. The nine principles are (ADA, 2010):
1.	Any regulation should require covered dental offices to comply with BMPs patterned
on the those developed by ADA (see Table 6-1), including the installation of
International Organization for Standardization (ISO) compliant amalgam separators
or separators equally effective;
2.	Any regulation should defer to existing state or local law or regulation requiring
separators so that the regulation would not require replacement of existing separators
compliant with existing applicable law;
3.	Any regulation should exempt dental practices that do not place or remove amalgams,
or only de minimis amounts of amalgams;
4.	Any regulation should include an effective date or phase-in period of sufficient length
to permit affected dentists a reasonable opportunity to comply;
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Chapter 6—Current National, State, and Local Dental Mercury Reduction Programs
5.	Any regulation should provide for a reasonable opportunity for covered dentists to
repair or replace defective separators without being deemed in violation of the
regulation;
6.	Any regulation should minimize the administrative burden on covered dental offices
by (e.g.) primarily relying upon self certification (subject to verification or random
inspection) and not requiring dental-office specific permits;
7.	Any regulation should not include a local numerical limit set by the POTW;
8.	Any regulation should not require wastewater monitoring at the dental office,
although monitoring of the separators to assure proper operation may be required; and
9.	Any regulation should provide that compliance with it shall satisfy the requirements
of the Clean Water Act unless a more stringent local requirement is needed.
6.2.3 ADA Health First Amalgam Recovery Program
In 2013, ADA joined with HealthFirst to establish an amalgam recovery program. ADA
chose HealthFirst as its endorsed amalgam recovery service provider. Through the HealthFirst
Amalgam Recovery Program, ADA members are able to purchase an amalgam separator at a
reduced cost. HealthFirst also offers waste handling services, including arranging the shipment,
tracking, and documentation of waste to permitted waste handlers. In addition, other supplies
such as chair-side traps, filters, and ADA-approved amalgam buckets can also be purchased
through the program (ADA News, 2013; ADA Business Resources, 2014).
6.3 State Dental Amalgam Requirements
EPA identified 12 states as having mandatory program requirements for dental offices; 11
of which require amalgam separators:
•	Connecticut;
•	Louisiana;18
•	Maine;
•	Massachusetts;
•	Michigan;
•	New Hampshire;
•	New Jersey;
•	New Mexico;
•	New York;
•	Rhode Island;
18 Louisiana state requirements under the Mercury Risk Reduction Act do not specifically require dental offices to
install amalgam separators; dental offices must follow 1999 BMPs recommended by the ADA. ADA did not add
amalgam separators to its list of BMPs until 2008.
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Chapter 6—Current National, State, and Local Dental Mercury Reduction Programs
•	Vermont; and
•	Washington.
At proposal of the draft dental category rule, EPA identified Oregon as a state with a
mandatory dental amalgam control program. However, based on a follow up discussion with
Oregon's Department of Environmental Quality, EPA found that the program is handled by the
Oregon Dental Association and is voluntary (ERG, 2016).
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 6-2 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 6-3 compares the state BMP requirements to the ADA BMPs.
Table 6-2. Summary of Elements of State Requirements
Element
Examples from State Requirements
Requirements
Install amalgam separators (CT, LA, MA, ME, MI, NH, NJ, NM, NY, RI, VT, WA).
Follow state BMPs (CT, LA, MA, MI, NH, NJ, NY, RI, VT, WA).
Do not flush waste amalgam down the drain (CT, LA, MA, MI, NH, NJ, NY, RI, VT).
Use neutral (or non-oxidizing) line cleaners (CT, LA, MA, MI, NJ, NY, RI, VT)
Amalgam separator
technology
specifications
Meet ISO 11143 Standard (CT, MA, ME, MI, NH, NJ, NM, NY, RI, VT, WA).
Operate at 95% efficiency (CT, MI, NH, NM, NY, VT).a
Operate at 98% efficiency (MA, ME).a
Operate at 99% efficiency (NY if new, RI).
Method for
demonstrating
compliance
Submit certification to state enviromnental agency or Control Authority (CT, LA, MA, ME,
NH, NJ, NM, NY, WA).
Maintain maintenance and servicing records (CT, MA, ME, NM, NY, RI, VT).
Maintain amalgam recycling or disposal records (CT, LA, MA, ME, NM, RI, VT).
Sources: U.S. EPA, 2016a; ERG, 2016.
a - In several states, if an office had an amalgam separator in operation prior to implementation of the state law, then
the state allowed the office to continue operating that separator at its current efficiency.
State dental mercury control programs specifically require amalgam separators that meet
the ISO 11143 standard except for Louisiana. Louisiana does not specifically require the use of
amalgam separators. Rather, the rule requires dental offices to meet the ADA guidelines
effective June 2006. ADA did not add the use of amalgam separators to its BMPs until 2008.
The majority of state programs that do specify meeting the ISO 11143 standard do not
explicitly state the standard year. Eight state programs have initiation or compliance dates prior
to 2008 (Connecticut, Louisiana, Maine, Massachusetts, New Hampshire, New York, Vermont,
and Washington), three in 2008 (Michigan, New Jersey, and Rhode Island), and one since 2008
(New Mexico).
The majority of state programs require the following BMPs, as described by ADA BMPs:
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Chapter 6—Current National, State, and Local Dental Mercury Reduction Programs
1.	Do not flush amalgam waste down the drain or toilet, and do not rinse chair-side traps
or vacuum pump filters containing amalgam over drains or sinks.19
2.	Do not use bleach or chlorine-containing cleaners to flush wastewater lines.20
Table 6-3. Mandatory BMPs by State and Comparison to ADA BMPs a'b
Best Management Practice
ADA
CT
LA
MA
ME
MI
NH
NJ
NM
NY
RI
VT
WA
Initial Use
Use only pre-capsulated alloys and/or
stock a variety of capsule sizes.
X
X
X


X
X
X

X



Do not use bulk mercury.
X

X


X

X

X



Recycling/Disposal
Manage amalgam waste through
recycling as much as possible.
X
X
X
X


X
X

X
X


Recycle used disposable amalgam
capsules.
X

X


X
X
X

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

X
X
X

X
X
X
X
Salvage, store and recycle non-contact
amalgam (scrap, or waste, amalgam).
X
X
X
X

X
X
X

X
X
X
X
Salvage amalgam pieces from
restorations after removal (contact
amalgam) and recycle amalgam waste.
X
X
X
X

X
X
X

X
X
X

Recycle teeth that contain amalgam
restorations.
X

X
X

X
X


X

X
X
Do not put used disposable amalgam
capsules in biohazard containers,
infectious waste containers (red bags)
or regular garbage.
X
X
X


X
X
X

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

X
X
X

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

X
X
X

X
X
X

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

X
X

X
X
X

X
X
X

19 EPA included a similar BMP in the final rule: waste amalgam (contact and noncontact), including but not limited
to dental amalgam from chair-side traps, screens, vacuum pump filters, dental tools, cuspidors, or collection devices
must not be flushed to the sewage collection system.
211 EPA included a similar BMP in the final rule: chair-side traps and vacuum lines that discharge to the sewage
collection system must be cleaned with neutral cleaners that have a pH between 6 and 8.
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Chapter 6—Current National, State, and Local Dental Mercury Reduction Programs
Table 6-3. Mandatory BMPs by State and Comparison to ADA BMPs a'b
Best Management Practice
ADA
CT
LA
MA
ME
MI
NH
NJ
NM
NY
RI
VT
WA
Chair-Side Traps
Use chair-side traps to retain amalgam
and recycle the content.
X

X
X

X
X
X

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


X
X

X
X
X
X
Where appropriate, disposable
amalgam traps are preferable to
reusable traps.

X




X


X
X


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

X
X


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


X
X

X
X
X
X
Use line cleaners that minimize the
dissolution of amalgam.
X

X
X





X
X
X

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

X

X

X
X
X

Amalgam Separators
Install and use amalgam separators.
X
X
X
X
X
X
X
X
X
X
X
X
X
Other
If using mercury, maintain a mercury
spill kit on site and train all staff on
mercury spill cleanup response
procedures.

X

X


X



X
X

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



X

X
X


X



Sources: ADA, 2007; CTDEP, 2006; Lamperti, 2007; Louisiana Legislature, 2006; MassDEP, 2007; Michigan
2012; NHDES 2002; NJR, 2007; NYDEC, 2007; RIDEM, 2007; VTDEC, 2006; and WADOE, 2005.
a - Neither Maine nor New Mexico included any BMPs as part of its requirement to install amalgam separators
(Maine DEP, 2005; New Mexico, 2014).
b - Louisiana state requirements under the Mercury Risk Reduction Act do not specifically require dental offices to
install amalgam separators; however, dental offices must follow BMPs recommended by the ADA. These BMPs
include the installation of amalgam separators (Louisiana Legislature, 2006).
Three states, Maine, New Mexico, and Washington do not list the BMPs as a state
requirement or only list them as guidance. New Hampshire requires the first BMP (no flushing),
but does not require the second BMP (use of neutral cleaners).
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Chapter 6—Current National, State, and Local Dental Mercury Reduction Programs
All states administer their programs through state environmental agencies. Most require
at least one-time reporting, however EPA did not find reporting requirements for three of the
state programs (Michigan, Rhode Island, and Vermont).
In addition to states with mandatory programs, four states (Florida, Idaho, Minnesota, and
Oregon) and the District of Columbia provide voluntary guidelines and BMPs to dental offices.
Table 6-4 summarizes the BMPs for these states and district and compares them to ADA's
BMPs.
Table 6-4. Voluntary BMPs by State and Comparison to ADA BMPs
Best Management Practice
ADA
DC
FL
ID
MN
OR
Initial Use
Use only pre-capsulated alloys and/or stock a variety of capsule sizes.
X
X
X
X

X
Do not use bulk mercury.
X
X
X
X

X
Recycling/Dispo sal
Manage amalgam waste through recycling as much as possible.
X
X
X
X
X
X
Recycle used disposable amalgam capsules.
X
X

X


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

X
X
Salvage, store, and recycle non-contact amalgam (scrap, or waste,
amalgam).
X
X

X
X
X
Salvage amalgam pieces from restorations after removal (contact amalgam)
and recycle amalgam waste.
X
X
X
X
X
X
Recycle teeth that contain amalgam restorations.
X

X
X


Do not put used disposable amalgam capsules in biohazard containers,
infectious waste containers (red bags), or regular garbage.
X
X
X

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

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

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

X

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


X


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

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

X
X
Use line cleaners that minimize the dissolution of amalgam.
X



X

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


X

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Chapter 6—Current National, State, and Local Dental Mercury Reduction Programs
Table 6-4. Voluntary BMPs by State and Comparison to ADA BMPs
Best Management Practice
ADA
DC
FL
ID
MN
OR
Amalgam Separators
Install and use amalgam separators.
X


X
X
X
Other
If using mercury, maintain a mercury spill kit on site and train all staff on
mercury spill cleanup response procedures.

X
X



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




X
X
Sources: ADA, 2007; District of Columbia Water and Sewer Authority, 2012; FLDEP, 2001; ISDA, 2008; MDA,
2003; Oregon State Legislature, 2007.
6.4 Local Dental Amalgam Requirements
EPA identified and reviewed 18 mandatory dental amalgam control program
requirements for the following localities that are not located in a state with a mandatory program:
•	East Bay Municipal Utility District (EBMUD), Oakland, CA;
•	Palo Alto, CA;
•	Central Contra Costa Sanitary District, Martinez, CA;
•	San Jose, CA;
•	Castro Valley, CA;
•	San Francisco, CA;
•	City of Fort Collins, CO;
•	Boulder, CO;
•	Metropolitan Wastewater Reclamation District, Denver, CO;
•	City of Loveland, CO;
•	Northeast Ohio Regional Sewer District, Cleveland, OH;
•	Eau Claire, WI;
•	Madison, WI;
•	Milwaukee, WI;
•	Wausau, WI;
•	Green Bay-De Pere, WI;
•	Waukesha, WI; and
•	Watertown, WI.
EPA also identified programs in Rhode Island (Narragansett Bay) and Washington (King
County Wastewater Treatment Division); however, all dental offices in those localities are
covered under the state program.
Sixteen of the 18 local programs specifically require amalgam separators that meet the
ISO 11143 standard. The other two programs are Palo Alto, California, which only refers to the
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Chapter 6—Current National, State, and Local Dental Mercury Reduction Programs
ADA BMPs (and did not include amalgam separators at the time of the program initiation); and
Central Contra Costa Sanitary District in Martinez, California, which requires an amalgam
separator but does not specify meeting the ISO 11143 standard. The majority of local programs
that do specify meeting the ISO 11143 standard do not explicitly state the standard year.
The majority of local programs require the following BMPs, as described by ADA
BMPs:
1.	Do not flush amalgam waste down the drain or toilet, and do not rinse chair-side traps
or vacuum pump filters containing amalgam over drains or sinks.
2.	Do not use bleach or chlorine-containing cleaners to flush wastewater lines.
The Central Contra Costa Sanitary District in Martinez, California does not list the BMPs
as part of its program, and EPA did not find information on the program for Eau Claire,
Wisconsin (identified in comments to the proposed rule). The Northeast Ohio Regional Sewer
District, Cleveland, Ohio program does not list the second BMP to use non-oxidizing line
cleaners. Three of the programs had no flush provisions but slightly more limited wording (San
Jose, California; Fort Collins, Colorado; and Boulder, Colorado).
As part of its costing analysis (see Chapter 9), EPA determined the number of dental
offices in localities and states with mandatory dental amalgam control programs. EPA assumed
that the dental offices located in an area with a mandatory program have amalgam separators
installed. Lists the number of dental offices by state and locality.
Table 6-5. Number of Dental Offices Located in States and Localities with Dental
Amalgam Control Program
State
Dental Offices that
May Place or
Remove Amalgam a
Locality
Dental Offices in State or Local
Program b
California
18,472
East Bay Municipal Utility
District (EBMUD), Oakland
404
Palo Alto
114
Central Contra Costa Sanitary
District, Martinez
214
San Jose
744
Castro Valley
unknown
San Francisco
571
TOTAL
2,047
Colorado
2,437
City of Fort Collins
61
Boulder
VO
O
o
Metropolitan Wastewater
Reclamation District, Denver
800 c
City of Loveland
30
TOTAL
981
Connecticut
1,554
Not applicable - state
program
1,554
Louisiana
1,396
Not applicable - state
program
1,396
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Chapter 6—Current National, State, and Local Dental Mercury Reduction Programs
Table 6-5. Number of Dental Offices Located in States and Localities with Dental
Amalgam Control Program

Dental Offices that



May Place or

Dental Offices in State or Local
State
Remove Amalgam a
Locality
Program b
Maine
418
Not applicable - state
program
418
Massachusetts
2,790
Not applicable - state
program
2,790
Michigan
3,739
Not applicable - state
program
3,739
Minnesota
1,738
Voluntary program through
Minnesota Dental
Association
l,477d
New
533
Not applicable - state
533
Hampshire

program

New Jersey
4,184
Not applicable - state
program
4,184
New Mexico
603
Not applicable - state
program
603
New York
8,088
Not applicable - state
program
8,088
Ohio
3,774
Northeast Ohio Regional
Sewer District (NEORSD),
Cleveland and Solon
104
Rhode Island
345
Not applicable - state
program
345
Vermont
227
Not applicable - state
program
227
Washington
3,106
Not applicable - state
program
3,106
Wisconsin
1,850
Eau Claire
24


Green Bay-De Pere
142


Madison
110 c


Milwaukee
360


Watertown
8


Waukesha
22


Wausau
14


TOTAL
680
a - The count of dental offices is based on the number of offices in the state as reported in the 2012 Economic
Census and national percent of dental offices that are general practices and specialty practices that may place or
remove amalgam (U.S. EPA, 2016b).
b - Estimated number of dental offices that may place or removal amalgam that discharge to the locality POTW
or total in state for mandatory state programs (U.S. EPA, 2016c).
c - Number of dental offices based on comment submitted on the proposed pretreatment standards for the dental
category. Boulder: EPA-HQ-OW-2014-0693-0445; Denver: EPA-HQ-OW-2014-0693-0500; Madison: EPA-HQ-
OW-2014-0693-0428.
d - Voluntary program where 85 percent of dental offices committed to install amalgam separators (Walsh, 2007).
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Chapter 6—Current National, State, and Local Dental Mercury Reduction Programs
6.5 Voluntary Programs
Some states and localities have initiated voluntary dental mercury reduction programs.
The following two subchapters summarize 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 programs verified the
participation rates. Table 6-6 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.
6.5.1 Voluntary Programs with High Participation Rates
This subchapter describes case studies of three voluntary programs (Duluth, Minnesota;
Wichita, Kansas; and Massachusetts) that achieved participation rates greater than 90 percent or
exceeded their goals for participation rates. It includes both local and state programs.
The Duluth, Minnesota 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.
Wichita 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 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
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Chapter 6—Current National, State, and Local Dental Mercury Reduction Programs
separators, and a discount waste disposal option through WLSSD's "Clean Shop" Program. As
of 2007, all of the dental offices had installed amalgam separators.
Wichita, Kansas
In April 2000, the Wichita Department of Water and Sewer initiated a code of mercury
management practices, which requires dental offices in Wichita to be equipped with devices to
reduce the amount of amalgam discharged into POTWs. Phase 1 was an effort to encourage
voluntary use of technologies beyond the chair-side trap and vacuum filter (e.g., an amalgam
separator). Phase 2 of the program would have required mandatory separators if the voluntary
effort were not successful. Phase 2 of the program was never implemented because originally 60
percent of the dental community complied voluntarily. According to ADA, as of 2007, 98
percent of the 200 dental offices in the city have complied with the 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's goals 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 Chapter 6.3,
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 offices 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 they had 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 amalgam separators to operate
at 98 percent efficiency (MassDEP, 2007).
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Chapter 6—Current National, State, and Local Dental Mercury Reduction Programs
Table 6-6. 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 code of mercury management practices.
Encouraged dentists to use technologies beyond chair-
side trap and vacuum filter (e.g., amalgam separator).
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 personnel at 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.
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Chapter 6—Current National, State, and Local Dental Mercury Reduction Programs
Table 6-6. 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.
254 members in the local dental
society.
54 (21%) of local dentists
attended the half-day training
session on BMPs.
76 (30%) of 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 (waste) amalgam, proper use of
chair-side traps and pump filters to manage 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.
Chapter 6.5.1 describes the mandatory program
implemented by the locality.
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: Larry Walker Associates, 2002; MassDEP, 2007; MU Extension 2007; Walsh, 2007; KCWTD, 2007; MMSD, 2008.
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Chapter 6—Current National, State, and Local Dental Mercury Reduction Programs
6.5.2 Voluntary Programs with Low Participation Rates
Two voluntary programs had participation rates below 50 percent. Similar to the
programs with high participation rates, these programs conducted extensive outreach to local
dentists to educate dentists on BMPs and the use of amalgam separators. Despite this effort,
participation in the programs remained low leading one of the two programs to implement
mandatory requirements for BMPs and amalgam separators.
Seattle and Kins 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 listed below (Cain and Krauel, 2004). The Society won a regional
environmental achievement award for its efforts to educate its members concerning mercury in
dental wastewater.
•	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 included:
•	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 participating dentists as "EnviroStars."
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
scrap (waste) amalgam, amalgam from chair-side traps, and pump filter sludge. King County
also contacted separator vendors to obtain lists of dental offices that had purchased and installed
separators, and of 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 (Cain and Krauel, 2004):
•	Less than half of dentists in the King County service area properly managed waste
amalgam.
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Chapter 6—Current National, State, and Local Dental Mercury Reduction Programs
•	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).
•	Approximately 10 percent of dental offices contracted with waste haulers and/or
mail-away firms.
•	Hundreds of pounds of mercury from dental amalgams were still being disposed of
annually in garbage, "red bags," sewers, and "unknown" places.
•	The costs for King County's voluntary program totaled over $250,000. During 1995—
2001, the program spent an estimated $4,500 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 success of this voluntary program, King County began a mandatory
program as of July 2003. Table 6-6 describes the mandatory regulations (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 through 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 chapter focuses on
participation rates for the voluntary program. Chapter 7 of this document discusses effectiveness
of BMPs on reducing mercury concentrations at POTWs.
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;
•	ADA 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 amalgam waste; and
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Chapter 6—Current National, State, and Local Dental Mercury Reduction Programs
•	A list of amalgam recyclers.
MU Extension also sent training materials by mail to dentists who did not attend the
course.
One year later, MU Extension 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 30 percent (76 dental offices). 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:
•	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 waste amalgam increased significantly after BMP
training while the improper disposal decreased.
•	The amount of amalgam waste 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 used 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 picked
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, MU's efforts were successful in educating dentists
on BMPs. However, the majority of the dentists in the 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).
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Chapter 6—Current National, State, and Local Dental Mercury Reduction Programs
6.5.3 Summary of Participation Rates in Voluntary Programs
Participation rates in voluntary programs are highly variable, ranging from as high as 100
percent of dentists in a community to as low as approximately 20 percent. Several programs that
experienced low participation rates conducted extensive outreach and had frequent interaction
with dentists. Therefore, the level of participation did not necessarily correspond to the level of
outreach and education. In a study prepared for the Association of Metropolitan Sewerage
Agencies (AMSA), the author noted that during the first year of implementation, regulatory
programs have higher participation rates than voluntary programs. However, over time (5 to 10
years), participation rates for well-implemented voluntary programs are similar to participation
rates for mandatory programs (Larry Walker Associates, 2002).
Voluntary programs that included the threat of a mandatory second phase had the highest
participation percentages. Examples of the mandatory second phase requirements included more
stringent requirements for reporting, or the requirement for higher amalgam separator efficiency
standards. To avoid the more stringent mandatory requirements, dental offices usually opted to
comply with the voluntary requirements. In addition, 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.
6.6 References
ADA (American Dental Association). 2007. Best Management Practices for Amalgam Waste.
Updated July 2007. Document Control Number (DCN) DA00165.
ADA. 2010. ADA Principles to be used to Develop Mandatory Separator Pretreatment Rule.
Washington, DC. October 29. DCN DA00137.
ADA Business Resources. 2014. HealthFirst Amalgam Recovery Program. Accessed 2014. DCN
DA00246.
ADA News. 2013. ADA Business Resources endorses HealthFirst's Amalgam Recovery
Program. November 2. DCN DA00245.
Anderson, N. 2007. Statement of Norris Anderson, Ph.D., Director, Office of Science and Health
Coordination, FDA. November 14. DCNDA00204.
Cain, A. and R. Krauel. 2004. U.S. EPA and Environment Canada. Options for Dental Mercury
Reduction Programs: Information for State/Provincial and Local Governments. A Report
of the Binational Toxics Strategy Mercury Workgroup. August 4. DCN DA00132.
CTDEP. 2006. Dental Use of Mercury. December 18.
http://www.ct.gov/dep/ cwp/ view.asp?a=2708&q= 323994&depNav GID=1638. DCN
DA00188.
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Chapter 6—Current National, State, and Local Dental Mercury Reduction Programs
District of Columbia Water and Sewer Authority. 2012. Notice of Final Rulemaking Vol 59 No
6. Washington DC. February. DCN DA00254.
EBMUD (East Bay Municipal Utility District). 2005. Pollution Prevention Program. January.
DCN DA00179.
ERG. 2016. Notes on Telephone Conversations with State Dental Amalgam Control Programs.
July 18, 2016. DCN DA00521.
FDA (U.S. Food and Drug Administration). 2008. Questions and Answers on Dental Amalgam.
DCN DA00218.
FLDEP (Florida Department of Environmental Protection). 2001. Best Management Practices for
Scrap Dental Amalgam: Guidelines for Dental Offices. October. DCNDA00178.
ISDA (Idaho State Dental Association). 2008. Best Management Practices (BMPs) for Dental
Offices. DCN DA00205.
KCWTD (King County Wastewater Treatment Division). 2007. King County Regulations for
Dental Wastewater Discharged to the Sewer. May 16. DCN DA00190.
Lamperti, L. 2007. City of Corvallis' Comments on EPA's Preliminary 2008 Effluent Guidelines
Program Plan. December 21. DCN DA00235.
Larry Walker Associates. 2002. Mercury Source Control and Pollution Prevention Program
Evaluation. Prepared for AMSA. March (Updated July). DCN DA00006.
Louisiana Legislature. 2006. The Louisiana Mercury Risk Reduction Act. Act No. 126. DCN
DA00068.
Maine DEP (Department of Environmental Protection). 2005. Dental Amalgam Separator
Systems (website), http://www.maine.gov/dep/water/wd/amalgam-separators/. DCN
DA00193.
MassDEP (Massachusetts Department of Environmental Protection). 2007. Dental
Amalgam/Mercury Recycling Program. DCN DA00191.
MDA (Minnesota Dental Association). 2003. Re: Amalgam Recovery. Take Preventive Action
Now. Capture Amalgam So It Doesn't Release Mercury. March.
http://www.mndental.org/client files/documents//amalgam recovery.pdf. DCN
DA00192.
Michigan. 2012. Dentistry - General Rules. Department of Licensing and Regulatory Affairs.
November 29.
http://drna.com/201Q 002 LR Dentistry Dental Amalgam Final Rules.pdf. DCN
DA00534.
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Chapter 6—Current National, State, and Local Dental Mercury Reduction Programs
MMSD (Madison Metropolitan Sewerage District). 2008. MMSD Mercury Pollutant
Minimization Program. Madison, WI. DCN DA00220.
MU Extension (University of Missouri Extension Environmental Assistance Center). 2007.
Maximizing Voluntary Reductions in Dental Amalgam Mercury: Reduction in Mercury
Discharges. EPA#E0000127. Pl-98765101-0. November. DCN DA00223.
New Mexico. 2014. Title 16, Chapter 5, Part 58: Dental Amalgam Waste. New Mexico Board of
Dental Health Care, http://164.64.110.239/nmac/parts/titlel6/16.005.0058.htm. DCN
DA00529.
NHDES (New Hampshire Department of Environmental Services). 2002. Best Management
Practices for Dental Offices in New Hampshire. January. DCN DA00194.
NJR (New Jersey Register). 2007. Requirements for Indirect Users — Dental Facilities. 39 NJR
4117(a). October 1. DCNDA00222.
NYDEC. 2007. Managing Dental Mercury, http://www.dec.ny.gov/chemical/8513.html. DCN
DA00195.
Oregon State Legislature. 2007. Senate Bill 704: An Act Relating to Mercury in Dental
Wastewater. June.
https://olis.leg.state.or.us/liz/2007Rl/Downloads/MeasureDocument/SB704. DCN
DA00196.
OSHA (Occupational Safety and Health Administration). 1997. The Dental Industry's Concerns
Regarding Compliance with Certain Provisions of the Hazard Communication Standard
(HCS). Letter to the American Dental Trade Association. February 6. DCN DA00214.
RIDEM (Rhode Island Department of Environmental Management). 2007. Mercury in Dental
Amalgam, http://www.dem.ri.gov/topics/mercury.htm. DCN DA00207.
U.S. EPA. 2016a. Interaction ofMandatory State and Local Dental Amalgam Reduction
Programs and the Dental Rule. Memorandum to the Public Record for the Dental
Category Final Rule. Office of Water. Washington, DC. December 6. DCNDA00524.
U.S. EPA. 2016b. Dental Office Cost Calculations. MS Excel® file. Office of Water.
Washington, DC. December. DCN DA00456.
U.S. EPA. 2016c. Control Authority Cost Calculations. MS Excel® file. Office of Water.
Washington, DC. December. DCN DA00457.
VTDEC (Vermont Department of Environmental Conservation). 2006. Environmental
Management for Dental Offices. September 19. http://www.mercvt.org/dental/index.htm.
DCN DA00197.
WADOE (Washington State Department of Ecology). 2005. Manage Dental Waste.
http://www.ecv.wa.gov/mercurv/mercury dental bmps.html. DCN DA00080.
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Chapter 6—Current National, State, and Local Dental Mercury Reduction Programs
Walsh, William. 2007. The American Dental Association's (ADA) Comments on EPA's Study
of a Pretreatment Requirement for Dental Amalgam. Pepper Hamilton, LLP. December
21. DCN DA00238.
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Chapter 7—Treatment Technologies and Best Management Practices (BMPs)
Chapter 7
Treatment Technologies and Best Management Practices
(BMPs)	
Dental offices employ various technologies and approaches for reducing or eliminating
pollutant discharges. As described earlier, some dental offices do not install or remove amalgam.
For those dental offices that do place or remove amalgam, as described in Chapter 5, chair-side
traps and vacuum pump filters reduce the pollutants in dental amalgam discharges. Further
reductions can be achieved by adding amalgam separators. To reduce the dissolved portion of
metals, dental offices can incorporate polishing technologies. Dental offices can also install
wastewater retention tanks to eliminate discharges to publicly owned treatment works (POTWs).
Finally, as described in Chapter 6, best management practices (BMPs) are integral to reducing
pollutants in dental discharges.
This chapter describes amalgam separators and polishing, including information on
treatment efficiency, and wastewater retention tanks. It also discusses BMPs that EPA identified
to reduce the discharge of dental amalgam resulting from activities not directly related to
amalgam restoration or removal.
7.1 Amalgam Separators
An amalgam separator is a device designed to remove solids (including amalgam) from
dental office wastewater. Dental wastewater that goes into the chair-side cuspidors might not go
through the amalgam separator, but dental practices can connect the chair-side drain to the
vacuum system.21 The amalgam separator is placed at a point in the vacuum line before the
vacuum line intersects with plumbing in other parts of the building, and separates solids from
wastewater. Most separator designs rely on the force of the dental office's vacuum to draw
wastewater into the separator. However, the separation of solids from the wastewater and the
flow of the wastewater out of the separator will depend on the design of the separator. A typical
plumbing configuration for a dental office outfitted with an amalgam separator is shown earlier
in this document, in Figure 5-1. Prior to wastewater entering the amalgam separator, some dental
amalgam is removed by the chair-side traps and vacuum filter traps. Dentists maintain the traps
by removing the solid particles collected by them into a bucket or other storage container, then
recycling or properly disposing of the dental amalgam waste (ERG and SolmeteX, 201 la). The
wastewater flow rate determines how often filters and traps need to be cleaned/replaced (Walsh,
2007).
7.1.1 Treatment Process, Design, and Operation
The configuration, size, and operation of the dental office all affect the choice of
separator design. Amalgam separators can use sedimentation, filtration, centrifugation, ion
exchange, or a combination of some or all of these methods to remove dental amalgam (ADA,
2007). Practically all amalgam separators currently on the market today use sedimentation
processes (with or without filtration) to settle out the solids from the wastewater because of its
21 Gravity-feed amalgam separators might also be installed at dental offices.
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Chapter 7—Treatment Technologies and Best Management Practices (BMPs)
effectiveness and operational simplicity. The high specific gravity of amalgam causes it to settle
readily from suspension in wastewater, which allows the dental office wastewater to be treated
effectively by sedimentation techniques (Fan et al., 2002). Baffles or tanks can reduce the speed
of the wastewater flow, allowing more amalgam particles to settle out. After the solids settle, the
wastewater is either pumped out, decanted during servicing, or pulled through the separator.
Sedimentation-based separators are the simplest types of separators to operate.
Filtration can enhance solids removal in sedimentation-based amalgam separators, or
may function as the primary treatment process of the separator (Fan et al., 2002). EPA is aware
of at least one type of separator that uses centrifugation, in which a centrifuge-based separator
spins the water and forces the heavier amalgam particles to the sides of the separator, while the
water discharges from the separator.
A few amalgam separators combine sedimentation (with or without filtration) with ion
exchange in the same unit. Ion exchange technology removes dissolved mercury by using a
chelating agent or proprietary resin. These separators often require special cleaning or additives
to maintain their efficiency. A few dental offices operate a separate ion exchange (or polishing)
system to remove dissolved mercury after the wastewater leaves the amalgam separator. See
Chapter 7.2. None of the separators that EPA identified in the literature review added chemicals
to enhance solids removal, although chemical and polymer additions have been effective in
precipitating a portion of dissolved mercury out of dental wastewater under certain conditions
(Fan et al., 2002).
There are two common designs for amalgam separators. The first is a two-chambered
separator design that consists of a base permanently plumbed into the vacuum line and a
replaceable filtration cartridge. The removable cartridge usually attaches to the bottom of the
permanent base. As wastewater enters the top of the separator unit, gravity separates the
wastewater from the air pulling it through the vacuum. Air from the vacuum continues through
the system by exiting a bypass at or near the top of the base chamber. Wastewater then falls
through the base of the separator and enters the filtration cartridge. As additional wastewater
enters the separator, the filtration cartridge will fill to capacity, and wastewater will begin to
collect at the bottom of the base chamber. Gravity forces wastewater in the separator through a
filtration device and out of the separator through a decanting tube on the side of the unit. The
wastewater leaves its solids in the filter, then continues through the vacuum system and
eventually discharges from the dental office and then to the sewer. The second design consists of
a single chamber that requires wastewater to travel through a filtration medium before it is drawn
out of the separator. These separators may be oriented vertically so that wastewater enters the top
of the unit and remains in the separator for some time, allowing the solids to settle. For either
design, when the filtration cartridge or the separator itself reaches its capacity for retained solids,
the cartridge must be replaced and/or the separator serviced by the recycling or waste vendor
(ERG, 2010 and ERG, 201 lb).
The performance of the amalgam separator depends directly on specific operational,
maintenance, and inspection activities. Once the separator reaches solids retention capacity,
vacuum suction will begin to diminish or, more commonly, the separator will enter bypass mode.
Wastewater running through a separator in bypass mode flows through the separator without
being filtered, rendering the separator ineffective. Because many separators can enter bypass
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Chapter 7—Treatment Technologies and Best Management Practices (BMPs)
mode without any noticeable effect on vacuum suction, it is vital that the unit be checked
periodically, and serviced if necessary. Further, it is preferable for the dental office to visually
identify when an amalgam separator is approaching capacity (such as indicators for 75 or 90
percent filled), as opposed to waiting until the device is at capacity and/or an alarm sounds
indicating the device is full. Manufacturers will typically recommend the frequency of checks
and service to ensure proper operation.
Solids collected by the amalgam separator may include dental amalgam, biological
material from patients, and any other solid material sent down the vacuum line. Manufacturer
instructions for servicing amalgam separators and for handling separator waste should be
followed. Some amalgam separator manufacturers also offer waste management services.
Services provided can include ensuring that waste collected by the separator is handled
according to state and local requirements, and providing necessary compliance documentation
for the office's recordkeeping requirements. If such services are not employed, the office should
dispose of amalgam waste in accordance with state and local requirements.
7.1.2 Standards for Amalgam Separators
The vast majority of amalgam separators on the market today have been evaluated for
their ability to meet the current American National Standards Institute's (ANSI) Standard for
Amalgam Separators (ANSI/ADA Standard No. 108 for Amalgam Separators). ANSI is the
coordinator of the U.S. voluntary consensus standards system. An International Organization for
Standardization (ISO) document may be nationally adopted as an ANS as written or with
modifications to its content that reflect technical deviations to the ISO standard that have been
agreed upon through a consensus process. In other words, a consensus of U.S. experts, in an
open and due process based environment, agreed that ISO 11143 with U.S. modifications is
appropriate for adoption as an ANS. This ANSI standard incorporates the ISO Standard for
Dental Amalgam Separators
(http://www.iso.org/iso/iso catalogue/catalogue tc/catalogue detail.htm?csnumber=42288).
The current ISO standard for amalgam separators is ISO 11143. ISO established a
standard for measuring amalgam separator efficiency by evaluating the retention of amalgam
solids using specified test procedures in a laboratory setting. In order to meet the ISO standard, a
separator must achieve 95 percent removal or greater of total solids. The solids sample must be
prepared from dental amalgam as detailed in the standard, and summarized below. The ISO
standard also includes certain design requirements and requirements for instructions for proper
use and maintenance. In addition, the U.S. EPA has evaluated some amalgam separator devices
under the Environmental Technologies Verification (ETV) program.
ISO Standard 11143. ISO 11143 calls for measuring amalgam separator efficiency by
evaluating the retention of particles that contain dental amalgam. ISO Standard 11143 requires
that an amalgam separator remove at least 95 percent by weight of amalgam particles (i.e., the
mixture of mercury with other metals that constitute the amalgam filling) when subjected to a
specific test method as detailed in the standard. The test for determining the efficiency must be
carried out when the amalgam separator is under both empty and full conditions. The ISO test for
removal efficiency uses 10.00 grams of amalgam particles that are composed of three portions of
different sizes (ISO, 2008):
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Chapter 7—Treatment Technologies and Best Management Practices (BMPs)
•	60 percent of the particles are 3.15 millimeters (mm) 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.
•	30 percent of the particles are 0.1 mm or smaller.
It also includes requirements that instructional material supplied by the manufacturer
include directions for use, operation, and maintenance. The standard classifies amalgam
separator systems by the method of separation: centrifugation, sedimentation, filtration, or
combination of the first three methods.
It is important to note that compliance with 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., 2006a). ISO Standard 11143 describes the set-up of the
testing apparatus, installation of the amalgam separator, step by step procedures to perform the
efficiency testing, and how to calculate the efficiency of the amalgam separator.
The ISO Standard 11143 also requires that amalgam separators include a warning system
to indicate when the collecting container should be emptied or replaced (before maximum
fillable volume is reached). The standard also requires an alarm system to indicate when the
collecting container has reached the maximum filling level specified by the manufacturer. The
alarm signal must remain activated until the dentist empties or replaces the collecting container
and/or filter. A final alarm system is also required to indicate a malfunction of the amalgam
separator.
Other requirements of the ISO Standard 11143 include a removable filling container for
the amalgam separator that the dentist can easily and safely remove without discharging any of
the contents into the public sewage system, a maximum fillable volume of the collecting
container (4 liters), and electrical safety requirements for installing an amalgam separator.
EPA/Environmental Technology Verification (ETY) 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 International, 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 of mercury in
potable water (APHA et al., 1998). The EPA/ETV standard protocol is not used nearly as widely
as the ISO Standard, likely due to its higher cost and the longer time required for sample
analysis. See http://www.epa.gov/etv/pubs/04 vp mercury.pdf.
7.1.3 Treatment Efficiencies for Amalgam Separators
Dental offices commonly use amalgam separators in conjunction with chair-side traps
and vacuum pump filters. Most chair-side traps can filter particles as small as 0.7 millimeter
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Chapter 7—Treatment Technologies and Best Management Practices (BMPs)
(mm) and vacuum filter traps can capture particles as small as 0.4 mm (Fan et al., 2002). The
combined removal rate of a well operated chair-side trap and vacuum filter is approximately 78
percent of amalgam particles (Vandeven and McGinnis, 2005). 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).
Studies have demonstrated that amalgam separators can achieve significant reductions in
the amount of mercury discharged from dental wastewater.
•	A 1998 Boston University study tested three commercially available amalgam
separators that used different separation technologies, including gravity settling,
settling/filtration, and mechanical centrifuge. The amalgam removal, and thus the
particulate mercury removal, efficiencies for the three technologies ranged from 95 to
99.9 percent. However, the study also noted that an effluent mercury 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 (i.e., the metals that constitute the amalgam filling), 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 (U.S.
EPA, 2005).
Table 7-1 provides a non-inclusive list of 26 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.22 As illustrated, all
separators meet or exceed the ISO Standard of 95 percent (amalgam solids efficiency), 23
separators exceed 97 percent efficiency, and 19 separators meet or exceed 99 percent efficiency
of amalgam particle removal. The separators described in Table 7-1 achieved a median
efficiency of 99.3 percent.
Table 7-1. Efficiency and Technology of 26 Amalgam Separators
Model
Manufacturer
Treatment Technology
Percentage of Amalgam
Removed (by weight)a
Data
Sources
AD 1000
American Dental
Accessories
Sedimentation, filtration,
ion exchange
99.3%
2,7
Amalgam Boss
M.A.R.S. Bio-Med
Processes
Sedimentation, filtration,
ion exchange
95.0%
3
Amalgam
Collector CE18
R&D Services
Sedimentation
99.6%
1,9
22 Mention of product and vendor names does not constitute an endorsement by EPA.
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Chapter 7—Treatment Technologies and Best Management Practices (BMPs)
Table 7-1. Efficiency and Technology of 26 Amalgam Separators
Model
Manufacturer
Treatment Technology
Percentage of Amalgam
Removed (by weight)a
Data
Sources
Amalgam
Collector CE24
R&D Services
Sedimentation
>99.9%
1,10
Amalgam
Collector CHI2
R&D Services
Sedimentation
>99.9%
1,10
ARU-10
Hygenitek
Sedimentation, filtration,
ion exchange
>99.9%
5,11
Asdex AS-10
Capsule Technologies
Filtration
99.0%
1,12
Asdex AS-20
Capsule Technologies
Filtration
99.0%
1,12
Asdex AS-20
American Dental
Accessories
Sedimentation
95.0%
1,5
Asdex AS-9
American Dental
Accessories
Filtration
99.0%
7
BU10
Dental Recycling North
America
Sedimentation
>99.9%
1,8
BU30
Dental Recycling North
America
Sedimentation
>99.9%
1,8
CATCHHG 400b
Rebec Enviromnental
Sedimentation
99.3%
13
CATCHHG 1000b
Rebec Enviromnental
Sedimentation
99.3%
13
Custom system
(previously Catch
9000 series)b
Rebec Enviromnental
Sedimentation
99.3%
13
ECO II
Metasys, distributed by
Pure Water
Development
Sedimentation
97.5%
1,4,5,10
Hg5
SolmeteX
Sedimentation
99.0%
1,14
Hg5 HV
SolmeteX
Sedimentation filtration
98.5%
1,14
Hg5 Mini
SolmeteX
Sedimentation filtration
99.4%
1,14
Liberty Boss
M.A.R.S. Bio-Med
Processes
Sedimentation filtration
ion exchange
99.4%
1,6
Merc II
Bio-Sym Medical
Sedimentation filtration
ion exchange
98.2%
5,9
MRU10
Dental Recycling North
America
Sedimentation filtration
>99.9%
2,8
MRU30
Dental Recycling North
America
Sedimentation filtration
>99.9%
8
MSS 1000
Maximum Separation
Systems
Sedimentation, filtration
99.5%
2,5,9
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Chapter 7—Treatment Technologies and Best Management Practices (BMPs)
Table 7-1. Efficiency and Technology of 26 Amalgam Separators
Model
Manufacturer
Treatment Technology
Percentage of Amalgam
Removed (by weight)a
Data
Sources
MSS 2000
Maximum Separation
Systems
Sedimentation, filtration
98.9%
2,4,5
Rasch AD-1500
American Dental
Accessories
Sedimentation
95.0%
1,5
Median
99.3%

a - This efficiency is based on the percentage of mercury in the form of dental amalgam removed by weight, as
instructed in ISO Standard 11143.
b - As part of the proposed rule analysis, EPA included two models for each series number (400, 1000, and 9000)
from Rebec Solutions. Based on a review of the company website, only one model for each series is now offered
(Rebec Enviromnental, 2016). To estimate the percent removal, EPA calculated the average of the two models in the
series. The removal efficiencies for the models are documented in ERG and Rebec Solutions, 2011.
Sources: (1) U.S. Air Force, 2011; (2) MCES, 2009; (3) MMSD and University of Wisconsin-Extension, 2006; (4)
Fan et al, 2002; (5) McManus and Fan, 2003; (6) MARS Bio Med Processes, 2012; (7) ERG and American Dental
Accessories, 2011; (8) ERG and DRNA, 2011; (9) Batchu, et. al., 2006a; (10) Cain and Krauel, 2004; (11) Condrin,
2004; (12) Capsule Technologies, 2011; (13) ERG and Rebec Solutions, 2011; (14) ERG and SolmeteX, 2011b.
Removal efficiencies documented in ERG, 2014. Calculation of median percent efficiency documented in U.S. EPA,
2016.
7.2 Polishing
Mercury from dental amalgam in wastewater is present in both particulate and dissolved
form. The vast majority (>99.6 percent) is particulate (Stone, 2004). The soluble mercury can be
removed using oxidation and chelation under appropriate conditions. An additional process
(sometimes referred to as polishing) uses ion exchange to promote removal of dissolved mercury
from wastewater. In contrast to amalgam separators that contain an ion exchange component in
the same unit where solids are collected (as discussed in the previous chapter), polishing via ion
exchange refers to a separate treatment system that removes dissolved mercury from wastewater
after the wastewater has gone through the separator.
Dissolved mercury has a tendency to bind with other chemicals, resulting in a charged
complex. Ion exchange is the process that separates these charged amalgam particles from the
wastewater. Ion exchange does not rely on physical settling of particles, and is advantageous
because it removes very small amalgam and ionic mercury particles. Sedimentation (with or
without filtration) alone does not remove dissolved mercury. Ion exchange might be useful, for
instance, in municipalities that have concentration limits on mercury (McManus and Fan, 2003).
EPA is not aware of any state regulations that require ion exchange.
For ion exchange to be most effective in removing dissolved mercury, the incoming
wastewater should first have the solids removed and then be oxidized (creating a charge on the
amalgam particles) in order for the resin, or other capturing material, to capture the dissolved
mercury. Therefore, ion exchange will not be effective without first being preceded by a solids
collector and an oxidation process. Mercury (Hg) in water will speciate into many complexes
including organic complexes, non-charged species, negatively charged and positively charged
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Chapter 7—Treatment Technologies and Best Management Practices (BMPs)
species. The variability of Hg ion charges makes ion exchange ineffective as a removal
technology under these conditions. The addition of chlorine to the wastewater as an oxidant is
used to manage the different species of mercury complexes into a single species (HgCh) for
adherence to a chelating resin. This was successful in the removal of mercury in solution from
the wastewater of several medical waste incinerators (EPA-HQ-OW-2014-0693-0329).
In a pilot ion exchange installation in Virginia for the U.S. Navy, it was found that high
levels of calcium in the water materially affected the removal rates and contact times required to
remove mercury to low part per billion results. This study was done using a sulfhydryl chemistry
applied to a polymeric, high surface area resin. Contact times to precipitate mercury from
dissolved mercury in laboratory conditions required only one minute of empty bed contact time.
Similar contact times were used in other applications quite successfully other than the pilot run
in Virginia. It was also found in another application for wastewater treatment by the U.S. Navy
that an activated carbon column and sub-micron filtration following the chelating resin showed
good soluble mercury removals. The project was stopped due to the cost of mercury chelating
resin in excess of $800 per cubic foot (ft3) (EPA-HQ-OW-2014-0693-0329).
These data suggest a sequential polishing approach, in which amalgam separators and ion
exchange are separate units, is more effective than the single units described above that combine
sedimentation and ion exchange to remove both suspended and dissolved mercury. Those dental
offices needing to employ polishing would likely need to add a separate ion exchange unit to
remove additional mercury from the waste stream after it leaves the amalgam separator.
As explained above, testing for compliance with the ISO standards is based on an
evaluation of the removal of amalgam solids in a laboratory setting and does not differentiate
between the suspended and dissolved forms. In order to understand more fully the reductions in
dissolved mercury that can be achieved with the addition of ion exchange polishing, EPA
reviewed available performance data from actual installations of ion exchange units and
amalgam separators in dental offices. EPA found the use of polishing is limited to a handful of
dental offices and found just one study of polishing systems. This study evaluated the additional
efficacy provided by polishing at two dental offices that were responding to sanitation district
concerns over their mercury discharges. The two dental offices in a sanitary district in Colorado
installed polishing columns with a holding tank to allow chlorine oxidation after the amalgam
separator but prior to the ion exchange columns. Preliminary EPA Region 8 audits showed the
total additional mercury reductions achieved by the polishing step were typically on the order of
0.5 percent (Garcia, 2009). This is consistent with the studies indicated above that demonstrate
that amalgam separators alone (without polishing) can remove 99.3 percent of total mercury on
average, and further consistent with other data showing dissolved mercury comprises a very
small percentage of the total amount of mercury in dental amalgam. It is unclear whether any
solid mercury was converted to dissolved mercury in these two systems, and additional
monitoring data are not yet available.
EPA found limited data on the costs of polishing systems (ERG, 201 la). The capital costs
of the polishing system, as a stand-alone system, are approximately four times that of the
amalgam separator (ERG, 201 la). EPA expects additional costs would occur for added chemical
use, the resin, regenerating the resin, filter replacement, and other operational costs. EPA is
aware of a number of operating installations of filtration, followed by chelating resin followed by
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Chapter 7—Treatment Technologies and Best Management Practices (BMPs)
activated carbon followed by 0.5 micron filtration, at several large dental schools in the United
States. However, the cost of these operations has yet to be collected and reported. Further, EPA
lacks data as to whether typical dental buildings have adequate space to install the holding tanks
and chemical feed tanks needed to oxidize the wastewater before treatment, as well as space for
the polishing column itself.
7.3	Wastewater Retention Tanks
Wastewater retention tanks are used at dental offices to collect and retain all amalgam
process wastewater.23 The wastewater remains in the wastewater retention tank until it is pumped
out of the tank and transferred to a privately owned wastewater treatment facility (also referred
to as centralized waste treatment facilities or CWT facilities). This technology eliminates the
discharge of amalgam process wastewater and the associated pollutants from a dental office to a
POTW. However, EPA identified only one vendor of this treatment technology. The vendor has
indicated that the technology is not available in all locations due to proximity of a privately
owned wastewater treatment facility licensed for such wastes, and due to the space needed for
holding tanks (Anterior Quest, 2015).
7.4	Best Management Practices
In addition to technologies, EPA also identified best management practices currently used
in the dental industry (and included in the ADA BMPs) to reduce dental amalgam discharges. In
particular, EPA identified two BMPs to control dental amalgam discharges that would not be
captured by an amalgam separator and/or polishing unit. Oxidizing line cleaners can solubilize
bound mercury. If oxidizing cleaners are used to clean vacuum lines that lead to an amalgam
separator, the line cleaners may solubilize any mercury that the separator has captured, resulting
in increased mercury discharges (Cain and Krauel, 2004; Batchu et al., 2006b). One BMP
ensures the efficiency of amalgam separators by prohibiting use of oxidizing line cleaners
including but not limited to, bleach, chlorine, iodine and peroxide, that have a pH lower than 6 or
greater than 8.24
Flushing waste amalgam from chair-side traps, screens, vacuum pump filters, dental
tools, or collection devices into drains also presents additional opportunities for mercury to be
discharged from the dental office. The second BMP prohibits flushing waste dental amalgam into
any drain.
7.5	References
ADA (American Dental Association). 2007. ADA Professional Product Review. Document
Control Number (DCN) DA00043.
23	Dental offices using wastewater retention tanks must ensure that the wastewater retention tanks collect all
amalgam process wastewater. Any uncollected amalgam process wastewater that is discharged to the POTW is
subject to the final rule.
24	Many alternatives use enzymatic or other processes that do not lead to the dissolution of mercury when used to
clean chairside traps, and vacuum lines. See DCN DA00215.
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Chapter 7—Treatment Technologies and Best Management Practices (BMPs)
Anterior Quest. 2015. Amalgam Containment and Recycling: Attaining Zero Mercury Discharge
in Dental Office Wastewater. Document Control Number (DCN) DA00461.
APHA, AWWA, and WEF (American Public Health Association, American Water Works
Association, and Water Environment Federation). 1998. Standard Methods for the
Examination of Water and Wastewater. DCN DA00216.
Batchu, H., D. Rakowski, P.L.Fan, and D.M. Meyer. 2006a. Evaluating Amalgam Separators
Using an International Standard. Journal of the American Medical Association, 137:999-
1005. DCN DA00183.
Batchu, H., H.N. Chou, D. Rakowski, and P.L. Fan. 2006b. The Effect of Disinfectants and Line
Cleaners on the Release of Mercury from Amalgam. Journal of the American Dental
Association, 137(10): 1419-1425. DCNDA00215.
Boston University. 1998. A New Prescription: Pollution Prevention Strategies for the Health
Care Industry. Tyngsborough, MA. October 7. DCNDA00170.
Cain, A. and R. Krauel. 2004. U.S. EPA and Environment Canada. Options for Dental Mercury
Reduction Programs: Information for State/Provincial and Local Governments. A Report
of the Binational Toxics Strategy Mercury Workgroup. August 4. DCN DA00132.
Capsule Technologies. 2011. Capsule Technologies—AS-9. DCNDA00226.
Condrin, A.K. 2004. The Use of CDA Best Management Practices and Amalgam Separators to
Improve the Management of Dental Wastewater. Journal of the California Dental
Association, 32(7):583-592. DCNDA00024.
ERG (Eastern Research Group). 2010. SolmeteX meeting minutes for 15 December 2010.
Chantilly, VA. DCN DA00081.
ERG. 2011a. Polishing System for Removing Dissolved Mercury Review. Memorandum.
Chantilly, VA. May 23. Document Control Number (DCN) DA00122.
ERG. 201 lb. Dental Recycling North America, Inc. (DRNA) Meeting Minutes for 19 January
2011. March 23. DCNDA00059.
ERG and American Dental Accessories. 2011. Email correspondence between Kimberly
Landick, ERG, and American Dental Accessories. February 28, 2011: Subject Request
for Amalgam Separator Information. DCN DA00061.
ERG and DRNA. 2011. Notes from telephone conversation between Kimberly Landick, ERG,
and Marc Sussman and Darwin Moreira, DRNA. March 1, 2011: Subject Amalgam
Separator Questions. DCN DA00062.
ERG and Rebec Solutions. 2011. Notes from telephone conversation between Kimberly Landick,
ERG and Rebec Solutions, March 2, 2011: Subject Amalgam Separator Questions. DCN
DA00063.
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Chapter 7—Treatment Technologies and Best Management Practices (BMPs)
ERG and SolmeteX. 201 la. Notes from telephone conversation between Kimberly Landick,
ERG and SolmeteX, May 10, 2011: Subject Polishing System for Removing Dissolved
Mercury. DCN DA00120.
ERG and SolmeteX. 201 lb. Notes from telephone conversation between Kimberly Landick,
ERG and SolmeteX, March 2, 2011: Subject Amalgam Separator Questions. DCN
DA00064.
ERG. 2014. Amalgam Separator Treatment Efficiencies. MS Excel® file. Chantilly, VA.
September. DCN DA00233.
Fan, P.L., H. Batchu, H.N. Chou, W. Gasparac, J. Sandrik, and D.M. Meyer. 2002. Laboratory
Evaluation of Amalgam Separators. Journal of the American Medical Association,
133:577-584. DCNDA00008.
Garcia, A. 2009. EPA Audit Follow-Up Report. U.S. EPA Region 8. September 15. DCN
DA00164.
ISO (International Organization for Standardization). 2008. ISO 11143 Dentistry—Amalgam
Separators, Second Edition. Geneva, Switzerland. DCNDA00138.
MARS Bio Med Processes. 2012. Liberty Boss. DCN DA00231.
MCES (Metropolitan Council Environmental Services). 2001. Evaluation of Amalgam Removal
Equipment and Dental Clinic Loadings to the Sanitary Sewer. December 21. DCN
DA00007.
MCES. 2009. Revised - Features of Approved Amalgam Separators. March.
http://www.mntap.umn.edu/healthcarehw/Dental/MCES-
MDA%20Approved%20Amalgam%20Separators.%20March%202009.pdf. DCN
DA00070.
McManus, K.R., and P.L. Fan. 2003. Purchasing, Installing and Operating Dental Amalgam
Separators. Journal of the American Dental Association, 134:1054-1065. DCN DA00162.
MMSD and University of Wisconsin Extension. 2006. Amalgam Management for Dental
Offices. http://www4.uwm.edU//shwec/publications/cabinet/pdf/DentalAmalgam2.pdf.
DCN DA00232.
NSF International (National Sanitation Foundation). 2001. Protocol for the Verification of
Mercury Amalgam Removal Technologies. DCN DA00176.
Rebec Environmental. 2016. Amalgam Separators (website).
http://rebecenvironmental.com/products/amalgam-separatorsA Accessed July. DCN
DA00472.
7-11
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Chapter 7—Treatment Technologies and Best Management Practices (BMPs)
Stone, M.E. 2004. The Effect of Amalgam Separators on Mercury Loading to Wastewater
Treatment Plants. Journal of the California Dental Association, 32(7):593-600. DCN
DA00018.
U.S. Air Force. 2011. Synopsis of Dental Amalgam Separators. January 24. Dental Evaluation
and Consultation Service.
http://airforcemedicine.afms.mil/idc/groups/public/documents/afms/ctb 124864.pdf.
DCN DA00079.
U.S. EPA. 2005. POTWMercury Control Strategy. EPA Region 8. Denver, CO. May 9. DCN
DA00180.
U.S. EPA. 2016. Amalgam Separator Cost Breakdown by Chair Size. MS Excel® file. Office of
Water. Washington, DC. December. DCN DA00454.
Vandeven, J., and S. McGinnis. 2005. An Assessment of Mercury in the Form of Amalgam in
Dental Wastewater in the United States. Water, Air and Soil Pollution, 164:349-366.
DCN DA00163.
Walsh, William. 2007. The American Dental Association's (ADA) Comments on EPA's Study
of a Pretreatment Requirement for Dental Amalgam. Pepper Hamilton, LLP. December
21. DCN DA00238.
7-12
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Chapter 8—Regulatory Options
Chapter 8
Regulatory Options	
As described below, EPA identified one technology that is available (as that term in used
in the CWA) to control dental amalgam discharges from the dental category: amalgam
separators. EPA further identified two best management practices (BMPs) that would further
reduce discharges of dental amalgam.
8.1 Pretreatment Standards For Existing Sources (PSES)
EPA decided to establish PSES based on proper operation and maintenance of one or
more ISO 1114325 compliant amalgam separators and two BMPs - a prohibition on the discharge
of waste (or "scrap") amalgam to publicly owned treatment works (POTWs) and a prohibition of
the use of line cleaners that are oxidizing or acidic and that have a pH higher than 8 or lower than
6. EPA finds that the technology basis is "available" as that term is used in the Clean Water Act
(CWA) because it is readily available and feasible for all dental offices subject to this rule. Data
in the record demonstrate that the technology basis is extremely effective in reducing pollutant
discharges in dental wastewater to POTWs as the median efficacy of International Organization
for Standardization (ISO) compliant amalgam separators on the market in the U.S. is 99.3
percent (U.S. EPA, 2016a). Moreover, the American Dental Association (ADA) recommends
that dentists use the technology on which this rule is based (ISO compliant amalgam separators
and BMPs). Further, EPA estimates that 40 percent of dental offices potentially subject to this
rule currently use amalgam separators on a voluntary basis or are in states or localities with laws
requiring the use of amalgam separators (U.S. EPA, 2016b). Many dentists have used amalgam
separators and BMPs for at least a decade. For those dental offices that have not yet installed an
amalgam separator, EPA estimates this is a low-cost technology with an approximate average
annual cost of $80026 per office. EPA's economic analysis shows that this rule is economically
achievable (see Chapter 10). Finally, EPA also examined the incremental non-water-quality
environmental impacts of the final pretreatment standards and found them to be acceptable. See
Chapter 14.
EPA did not establish PSES based on technologies that remove dissolved mercury such
as polishing. EPA is not aware of any state or local regulations that require ion exchange or that
require removal of dissolved mercury. Commenters raised operational concerns with ion
exchange citing a pilot study for the department of Navy. EPA also lacks adequate performance
data to assess the efficacy of polishing for nationwide use. While even very small amounts of
mercury have environmental effects, EPA lacks sufficient data to conclude that there is a
significant difference in the performance between traditional amalgam separators and polishing.
Moreover, current information suggests that polishing is not available for nationwide use
because the typical dental office may not have adequate space to install the treatment train
needed for effective polishing and because there are few polishing systems on the market today
in comparison to traditional amalgam separators. Lastly, EPA estimates that the capital costs of
25 ISO 11143 Standard as incorporated and updated by ANSI Standard 108 (ANSI 108/ISO 11143 Standard)
26This estimate is based on the average annualized cost for dental offices that do not currently have an amalgam
separator (U.S. EPA, 2016c).
8-1
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Chapter 8—Regulatory Options
the polishing system, as a stand-alone system, are approximately four times that of the amalgam
separator, even though the costs for chemical use, regenerating the resin, filter replacement, and
other operational costs were not reported (ERG, 2011). These factors led EPA to find that
polishing is not "available" as that term is used in the CWA.
EPA also did not establish PSES based on wastewater retention tanks. Capital costs for
wastewater retention tanks are approximately twice that of the amalgam separator (Anterior
Quest, 2015). EPA does not have information on the costs incurred by the dental office to send
the collected wastewater off-site to a privately owned treatment facility (may also be referred to
as a centralized waste treatment facility or CWT). Furthermore, wastewater retention tanks
require space, and EPA determined that the typical dental office may not have adequate space to
install the tanks. In addition, EPA is only aware of one vendor currently offering this technology
and service combination (vendor transfers the collected wastewater to a privately owned
treatment facility), and the vendor's service area is limited to a few states. Therefore, EPA did
not find this technology to be available to the industry as a whole.
8.2	Pretreatment Standards For New Sources (PSNS)
EPA decided to establish PSNS based on the same technologies identified above as
PSES. As previously noted, under section 307(c) of the Clean Water Act (CWA), new sources of
pollutants into POTWs must comply with standards that reflect the greatest degree of effluent
reduction achievable through application of the best available demonstrated control technologies.
Congress envisioned that new treatment systems could meet tighter controls than existing
sources because of the opportunity to incorporate the most efficient processes and treatment
systems into the facility design. The technologies used to control pollutants at existing offices,
amalgam separators and BMPs, are fully available to new offices. In addition, data from EPA's
record show that the incremental cost of an amalgam separator compared to the cost of opening a
new dental office is negligible; therefore, EPA determined that the final PSNS present no barrier
to entry (see Chapter 10). Similarly, because EPA projects that the incremental non-water quality
environmental impacts associated with controls for new sources would not exceed those for
existing sources, EPA concludes the non-water quality environmental impacts are acceptable.
Therefore, this final rule establishes PSNS that are the same as those for PSES.
EPA rejected other technologies as the basis for PSNS for the same reasons the Agency
rejected other technology bases for PSES.
8.3	References
Anterior Quest. 2015. Amalgam Containment and Recycling: Attaining Zero Mercury Discharge
in Dental Office Wastewater. Document Control Number (DCN) DA00461.
ERG (Eastern Research Group). 2011. Polishing System for Removing Dissolved Mercury
Review. Memorandum. Chantilly, VA. May 23. DCN DA00122.
U.S. EPA. 2016a. Amalgam Separator Cost Breakdown by Chair Size. MS Excel® file. Office of
Water. Washington, DC. December. DCN DA00454.
8-2
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Chapter 8—Regulatory Options
U.S. EPA. 2016b. Dental Office Cost Calculations. MS Excel® file. Office of Water.
Washington, DC. December. DCN DA00456.
U.S. EPA. 2016c. Economic Analysis for the Final Dental Amalgam Rule. MS Excel® file.
Office of Water. Washington, DC. December. DCN DA00458.
U.S. EPA. 2016d. Limited Emergency Removals of Dental Amalgam. Memorandum to the Public
Record for the Dental Category Final Rule. Office of Water. Washington, DC. August 6.
DCN DA00467.
8-3
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Chapter 9—Costs of Technologies
Chapter 9
Costs of Technologies	
This chapter provides information on EPA's approach for estimating incremental
compliance costs for dental offices to implement the final rule. The subsections below present an
overview of EPA's cost methodology, including use of model dental offices and calculation of
increment compliance costs for dental offices.
9.1 Methodology For Developing Model Dental Office Costs
EPA estimated incremental compliance costs for dental offices to comply with the final
rule using data collected through EPA's Health Services Industry Detailed Study (August 2008)
[EPA-821-R-08-014], a review of the literature, information supplied by vendors, and data
submitted with comments on the proposed rule. EPA estimated costs for the following
components: one-time costs (purchase and installation of technologies and completion of the
One-Time Compliance Report), annual costs that occur on a regular ongoing basis (e.g.,
inspection, operation and maintenance (O&M), and purchase of amalgam retaining units (e.g.,
containers, cartridges, or filters)), and recordkeeping costs.
The cost estimates reflect the incremental costs attributed only to this final rule. For
example, offices required by a state or local program to have an amalgam separator compliant
with the 2008 ISO 11143 standard (or its equivalent) will not incur costs to retrofit a separator as
a result of this rule. Others may certify to their Control Authority that they do not place or
remove amalgam. Such offices may still have costs under this final rule such as those associated
with the one-time reporting requirement (One-Time Compliance Report) to certify to their
Control Authority that they do not place or remove amalgam. EPA's cost methodology assumes
dental offices would use the required BMPs in combination with amalgam separators that meet
the 2008 ISO 11143 standard (see Chapter 7.1.2). All final cost estimates are expressed in terms
of 2016 dollars.
EPA develops national level incremental cost estimates for dental offices within the
scope of the regulatory options. In general, facility specific data can be used to determine what
changes, if any, a given facility would likely need to make to meet the requirements of a
regulatory option. This approach requires substantial facility-specific technical information. In
the case of the dental category, EPA would need such data for approximately 117,000 dental
offices estimated to be subject to the final rule. Such data are not available. An alternative
approach often used by EPA is to develop a series of model facilities that exhibit the typical
characteristics of affected facilities, then calculate costs for each model facility. EPA can then
determine how many affected facilities each model facility represents, and apply the appropriate
model costs, thereby modeling the full universe of affected facilities. This is the approach EPA
used to project the incremental costs to affected dental offices to meet the requirements in the
final rule.
9-1
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Chapter 9—Costs of Technologies
9.1.1	Model Dental Offices
Based on a review of the literature and discussion with amalgam separator vendors, EPA
determined that the dental office characteristic that drives many of the costs associated with this
rule is the number of chairs in an office. EPA developed costs for seven model dental offices,
where each model is based on the number of chairs in an office. The ranges for each model are as
follows: 1 to 2 chairs, 3 chairs, 4 chairs, 5 chairs, 6 chairs, 7 to 14 chairs (average of 10 chairs),
and 15 chairs.
EPA developed the 15 chair model dental office specifically to represent large,
institutional offices. Large, institutional dental offices (i.e., military clinics or dental schools)
have a larger number of chairs than the typical dental office. EPA has cost information for five
amalgam separators that have a maximum design ranging from 17-22 chairs. EPA also has costs
for a unit that can be custom sized for chair sizes of 16 or greater. EPA used the information for
these six separators to estimate costs for large, institutional facilities (U.S. EPA, 2016a). This is
labelled as 15 chairs in the table below, since it represents a model with more than 7-14 chairs
(the penultimate model chair size). EPA's costs for institutional facilities are likely overstated as
they do not reflect opportunities the largest offices may have to share costs, and they do not
assume any economies of scale. For example, multiple offices located in a single building or
complex may be able to share plumbing, vacuum systems, and may be able to install a larger
amalgam separator rather than each office having its own separator. In addition, it is possible that
the largest offices have multiple plumbing lines, in particular multiple vacuum systems, allowing
the installation of dental amalgam separators (or equivalent devices) only for those chairs used
for placing or removing amalgam.
9.1.2	Incremental Compliance Costs for Model Dental Offices
EPA developed two sets of costs for each model: one for dental offices that do not use an
amalgam separator and one for offices that do use an amalgam separator.
For dental offices that do not currently use an amalgam separator, EPA included the
following incremental compliance costs for dental offices to meet the requirements of the final
rule:
•	One-time costs (purchase and install a separator, One-Time Compliance Report):
capital costs to purchase an amalgam separator that meets the 2008 ISO 11143
standard and associated installation costs. EPA also included capital and installation
costs to replace the separator at the end of the assumed service life (10 years) in its
economic analysis. Costs include those associated with the One-Time Compliance
Report.
•	Annual costs: labor costs associated with visual inspections and operation and
maintenance of the separator (separator maintenance, recycling preparation),
replacement of the amalgam retaining unit, and recycling services.
•	Periodic costs: labor costs associated with separator repair and recordkeeping of the
repair and other recordkeeping (documentation of visual inspections, separator
9-2
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Chapter 9—Costs of Technologies
maintenance, and recycling). EPA also included the cost associated with submitting a
transfer in ownership form.
The following subchapters provide further details on each of these incremental
compliance costs.
9.1.2.1 One-time Costs for Dental Offices
For those dental offices without an amalgam separator, EPA's cost methodology assumes
dental offices would use 2008 ISO 11143 amalgam separators to comply with the rule. Many
amalgam separator models are plumbed into the vacuum systems. However, chair-side traps and
vacuums are installed as standard industry practice with dental chairs, and therefore EPA did not
include capital costs for chair-side traps and vacuum systems as part of the incremental
compliance costs of this rule (ERG & SolmeteX, 2011).
As shown in Table 7-1 in Chapter 7, EPA collected information on a non-inclusive list of
26 commercially-available amalgam separators identified by manufacturers as meeting the 2008
ISO 11143 standard27. EPA also used information on the amalgam separators included in Table
7-1 to estimate costs related to amalgam separators including purchase cost. Table 9-1 provides a
summary of these separators and their related costs (in 2016 dollars). As shown in Table 9-1, the
costs of amalgam separators vary, generally relative to the size (number of chairs) of the dental
office. EPA assumed each model facility needs a single amalgam separator, with the separator
size depending on the number of chairs in an office and the amalgam separator model. In some
cases, a vendor offers more than one amalgam separator model than is designed to provide
service for a specified number of chairs. EPA has not identified where purchase and installation
of multiple smaller amalgam separator units would cost less than a single unit; however, to the
extent the purchase and installation of multiple amalgam separators would be less expensive for
a particular dental office, the costs used here are overstated. Similarly, if two or more dental
offices, such as neighboring offices in a medical complex, could share an amalgam separator
(taking advantage of economy of scale), EPA's costs are overstated. Manufacturer suggested
retail prices (MSRP) range from $228 for a single chair unit to $4,510 (2016 dollars) for a
custom unit serving over 15 chairs.
EPA calculated the one-time purchase costs as follows. EPA only used the costs of the 26
amalgam separators that meet the 2008 ISO 11143 standard. The separator costs are shown in
Table 9-1, including the vendor specification of the number of chairs for which the specified
separator model could be used. EPA's cost model includes several model dental offices that
differ by the number of chairs: 1 to 2 chairs; 3 to 5 chairs; 6 chairs; 7 to 14 chairs; and 15 chairs
including large institutional offices. Next EPA calculated the average cost of those separators
that are appropriately used for each chair size model dental office. For example, the cost for an
amalgam separator for an office with three to five chairs is the average cost of each amalgam
separator model in Table 9-1 that could be used in a three to five chair office setting. See the MS
Excel® Cost Breakdown by Chair Size (U.S. EPA, 2016a) for the detailed calculations.
27 There may be additional amalgam separators on the market that meet the 2008 ISO 11143 standard for which EPA
does not have information.
9-3
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Chapter 9—Costs of Technologies
Table 9-1. Cost of Purchasing, Operating, and Maintaining Amalgam Separators ($2016)
Manufacturer
& Model Name
Treatment
Technology
Number
of Chairs
ISO Compliance
Notes (Reference)
Equipment
(Ca
Cost $2016,
pital)
Replacement Parts Cost $2016 (Annual
O&M)
Recycling
Cost" $2016
Annual
(g)
References
Min
Max
Parts
Min
Max
R&D Services:
Amalgam
Collector -
CH12
Sedimentation
1 chair
Transparent container
to monitor sludge
collection (USAF,
2011); Yes (R&D
Services, 2016)
$645.00
$645.00
Canister or
Recycling
service only
(reuse
canister)
$0.00
$345.14
$57.52
USAF, 2011;
R&D Services,
2016
Capsule
Technologies:
Asdex AS-10
Filtration
1 chair
Yes. Procedures from
manufacturer: when
filter is 90% full,
suction begins to
degrade (USAF,
2011).
$252.50
$252.50
Filter (every 6
to 8 months)
$160.93
$214.57
Not
included
USAF, 2011
American Dental
Accessories:
Asdex AS-9
Filtration
1 chair
Yes (ADA, 2007;
ERG American
Dental Accessories,
2011)
$227.52
$227.52
Filter (every 6
mos)
$173.28
$173.28
Not
included
ERG &
American
Dental
Accessories,
2011
Solmetex: Hg5
Mini (a)
Filtration,
Sedimentation
1 to 4
Visual check of
container till level
(USAF, 2011); ISO
Certificate available
online (Solmetex,
2016)
$812.76
$812.76
Collection
container
(every 6 to 12
mos)
$324.02
$648.04
$0.00
USAF, 2011;
Solmetex, 2016
Capsule
Technologies:
Asdex AS-20 (a)
Filtration
2 to 4
Yes. Procedures from
manufacturer: when
filter is 90% full,
suction begins to
degrade (USAF,
2011).
$359.78
$359.78
Filter (every 6
to 8 months)
$321.85
$431.31
Not
included
USAF, 2011
American Dental
Accessories:
Asdex AS-20
American Dental
(a)
Sedimentation
1 to 4
Yes (ERG &
American Dental
Accessories, 2011)
$325.05
$325.05
Filter (change
every 9 mos)
$255.67
$255.67
Not
included
ERG &
American
Dental
Accessories,
2011
Pure Water
Development:
ECO II
Sedimentation
1 to 5
Yes according to
website (Pure Water
Development, 2016)
$606.86
$606.86
Canister
$223.24
$223.24
$138.71
USAF, 2011
9-4
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Chapter 9—Costs of Technologies
Table 9-1. Cost of Purchasing, Operating, and Maintaining Amalgam Separators ($2016)
Manufacturer
& Model Name
Treatment
Technology
Number
of Chairs
ISO Compliance
Notes (Reference)
Equipment
(Ca
Cost $2016,
pital)
Replacement Parts Cost $2016 (Annual
O&M)
Recycling
Cost" $2016
Annual
(K)
References
Min
Max
Parts
Min
Max
Rebec
Environmental:
CATCHHG 400
(b)
Sedimentation
1 to 5
Company website
marketing a
CATCHHG 400
amalgam separator
that meets 2008 ISO
11143 standard
(Rebec
Environmental,
2016).
$1,284.16
$1,479.23
Canister (2
for plus
series)
$482.24
$698.97
$0.00
Rebec
Environmental,
2016; USAF,
2011
M.A.R.S. Bio-
Med Processes:
Amalgam Boss
(c,d)
Filtration, Ion
Exchange,
Sedimentation
4 to 10
Visual check of
separator fill level
(USAF, 2011); ADA,
2007 indicates an
alarm
$1,082.60
$1,082.60
Separator
Unit
$1,082.60
$1,082.60
$0.00
USAF, 2011
R&D Services:
Amalgam
Collector - CE18
Sedimentation
1 to 6
Transparent container
to monitor sludge
collection (USAF,
2011)
$895.00
$1,320.00
Canister or
Recycling
service only
(reuse
canister)
$0.00
$287.62
$153.01
R&D Services,
2016; USAF,
2011
Hygenitek:
ARU-10
Filtration, Ion
Exchange,
Sedimentation
1 to 6
Yes (NH, 2015)
$982.70
$982.70
Filter canister
(every 6 mos)
and Settling
Tank (every 6
to 12 mos)
$403.41
$496.02
$0.00
SF
Environment,
2005;
McManus &
Fan, 2003
Bio-Sym
Medical
Association:
Merc II
Filtration, Ion
Exchange,
Sedimentation
1 to 8
Yes (NH, 2015)
$2,032.76
$2,032.76
Cartridge
$777.00
$777.00
$0.00
McManus &
Fan, 2003
9-5
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Chapter 9—Costs of Technologies
Table 9-1. Cost of Purchasing, Operating, and Maintaining Amalgam Separators ($2016)
Manufacturer
& Model Name
Treatment
Technology
Number
of Chairs
ISO Compliance
Notes (Reference)
Equipment
(Ca
Cost $2016,
pital)
Replacement Parts Cost $2016 (Annual
O&M)
Recycling
Cost" $2016
Annual
(K)
References
Min
Max
Parts
Min
Max
DRNA: BU10
Sedimentation
1 to 8
Yes, see
httD://www.dma.com
/ISO ComDliant.html
and NH, 2015 [Note
ADA, 2007 state no
intervention warning]
$812.76
$812.76
Canister
(recycled)
$541.84
$541.84
$0.00
ERG &
DRNA, 2011
DRNA: MRU10
Filtration,
Sedimentation
1 to 8
NH, 2015 lists as ISO
compliant; No
intervention warning
(ADA, 2007)
$1,354.60
$1,354.60
Canister
(recycled)
$1,295.00
$1,295.00
$0.00
ERG &
DRNA, 2011
Solmetex: Hg5
Sedimentation
1 to 10
Visual check of
container fill level
(USAF, 2011); ISO
Certificate available
online (Solmetex,
2016)
$812.76
$812.76
Canister/conta
iner (every 6 -
12 mos)
$324.02
$648.04
$0.00
USAF, 2011;
Solmetex, 2016
M.A.R.S. Bio-
Med Processes:
Amalgam Boss
(c, d)
Filtration, Ion
Exchange,
Sedimentation
4 to 10
Visual check of
separator fill level
(USAF, 2011); ADA,
2007 indicates an
alarm
$1,082.60
$1,082.60
Separator
Unit
$1,082.60
$1,082.60
$0.00
USAF, 2011
Maximum
Separation
Systems:
MSS 1000
Filtration,
Sedimentation
1 to 11
Yes (NH, 2015)
$1,523.30
$1,523.30
Settling
Tanks
$211.04
$211.04
$290.39
MMSD&
Univ of WI,
2006;
McManus &
Fan, 2003
American Dental
Accessories:
AD-1000 (e)
Filtration, Ion
Exchange,
Sedimentation
7 to 12
Yes (ERG &
American Dental
Accessories, 2011)
$862.61
$862.61
Filter (18 mos
per dentist)
$760.46
$1,522.07
Not
included
MCES, 2009;
ERG and
American
Dental
Accessories,
2011
9-6
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Chapter 9—Costs of Technologies
Table 9-1. Cost of Purchasing, Operating, and Maintaining Amalgam Separators ($2016)
Manufacturer
& Model Name
Treatment
Technology
Number
of Chairs
ISO Compliance
Notes (Reference)
Equipment
(Ca
Cost $2016,
pital)
Replacement Parts Cost $2016 (Annual
O&M)
Recycling
Cost" $2016
Annual
(K)
References
Min
Max
Parts
Min
Max
American Dental
Accessories:
Rasch AD-1500
(e)
Sedimentation
7 to 12
Yes (ERG &
American Dental
Accessories, 2011)
$731.43
$731.43
Filter (18
mos)
$679.47
$1,357.85
$0.00
ERG and
American
Dental
Accessories,
2011
R&D Services:
Amalgam
Collector - CE24
Sedimentation
1 to 12
Transparent container
to monitor sludge
collection (USAF,
2011).
$1,315.00
$1,740.00
Canister or
Recycling
service only
(reuse
canister)
$0.00
$345.14
$230.09
USAF, 2011;
R&D Services,
2016
Rebec Solutions:
CATCHHG 1000
(b)
Filtration,
Sedimentation
6 to 15
Company website
marketing a
CATCHHG1000
amalgam separator
that meets 2008 ISO
11143 standard
(Rebec
Environmental,
2016).
$2,161.95
$2,177.12
Canister (2
for plus
series)
$482.24
$698.97
$0.00
Rebec
Environmental,
2016; USAF,
2011
Maximum
Separation
Systems:
MSS 2000
Filtration,
Sedimentation
12 to 22
Yes (NH, 2015)
$2,189.73
$2,189.73
Settling
Tanks(2)
$518.00
$518.00
$580.79
McManus &
Fan, 2003
MA.R.S. Bio-
Med Processes:
Liberty Boss (!)
Filtration, Ion
Exchange,
Sedimentation
11 to 17
Visual check of
separator till level
(USAF, 2011). ADA,
2007 indicates an
alarm
$1,678.62
$1,678.62
Separator
Unit
$1,678.62
$1,678.62
$0.00
USAF, 2011
DRNA: MRU30
Filtration,
Sedimentation
1 to 20
NH, 2015 lists as ISO
compliant; No
intervention warning
(ADA, 2007)
$1,945.21
$1,945.21
Canister
$1,511.74
$1,511.74
$0.00
ERG &
DRNA, 2011
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Chapter 9—Costs of Technologies
Table 9-1. Cost of Purchasing, Operating, and Maintaining Amalgam Separators ($2016)
Manufacturer
& Model Name
Treatment
Technology
Number
of Chairs
ISO Compliance
Notes (Reference)
Equipment
(Ca
Cost $2016,
pital)
Replacement Parts Cost $2016 (Annual
O&M)
Recycling
Cost" $2016
Annual
(K)
References
Min
Max
Parts
Min
Max
Solmetex: Hg5
High Volume
Filtration,
Sedimentation
10 to 20
Visual check of
container fill level
(USAF, 2011); ISO
Certificate available
online (Solmetex,
2016)
$2,709.21
$2,709.21
Container (2),
change every
6 to 12 mos
$650.21
$1,300.42
$0.00
USAF, 2011;
Solmetex, 2016
Rebec Solutions:
Catch 9000
(Custom
systems) (b)
Sedimentation
16 to
custom
Company website
marketing custom
systems that meet
2008 ISO 11143
standard (Rebec
Environmental,
2016).
$4,509.85
$4,509.85
Container (3),
change every
year
$969.90
$969.90
$0.00
Rebec
Environmental,
2016; USAF,
2011 ; MCES,
2009
DRNA: BU30
Sedimentation
7 to 20
USAF, 2011 says
"yes"; no note about
alarms; ADA, 2007
says no intervention
warning
$1,511.74
$1,511.74
Canister,
annual
replacement
$812.76
$812.76
$0.00
USAF, 2011;
ERG and
DRNA, 2011
Source: U.S. EPA, 2016a.
a - Amalgam separator model can be used for either dental offices that have 1 to 2 chairs or dental offices that have 3 to 5 chairs. EPA used the costs associated
with this particular model separator in its calculation of average costs for both model dental office size categories.
b - For proposed rule costing analysis, EPA included two Catch 400 series models; two Catch 1000 series models; and two Catch 9000 custom system models.
Only one is now available as shown on website (Rebec Enviromnental, 2016), for final rule costing analysis, EPA used one separator of appropriate size,
c - Amalgam separator model can be used for dental offices that have 6 chairs or dental offices that have 7 to 14 chairs. EPA used the costs associated with this
particular model separator in its calculation of average costs for both model dental office size categories.
d - Manufacturer recommends replacing unit every two years for 1 chair; every 1.5 years for 2 to 3 chairs; and every year for 4-10 chairs (USAF, 2011). EPA
did not include this separator model in its calculation of average costs for the 1 to 2 chair or 3 to 5 chair model dental office size categories. To estimate
compliance costs for the 6 chair model, EPA assumed the dental office would replace the unit at a minimum of once per year.
e - Manufacturer recommends replacing filter every 18 months for one dentist (MCES, 2009). To estimate annual cost for filter replacements, EPA assumed a
dental office with 7 to 12 chairs would have 2 to 4 dentists. This assumption is based on the Safety Net Dental Clinic Manual which recommends 3 operatories
(dental chairs) per dentist (National Maternal & Child Oral Health Resource Center, 2011).
f- Manufacturer recommends new unit every year for offices with 11 to 17 chairs (USAF, 2011).
g - Average recycling costs for all units is $82 per year ($2016).
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Chapter 9—Costs of Technologies
For initial separator installation, EPA used a similar cost methodology. EPA obtained
installation costs from multiple sources (Behm, 2008; ERG, 2010; King County, 2005;
McManus & Fan, 2003; SF Environment, 2005; MMSD & University of Wisconsin - Extension,
2006; U.S. EPA, 2003). EPA then calculated the average installation cost for each model dental
office based on the number of chairs represented by the model office: 1 to 2 chairs; 3 to 6 chairs;
7 to 14 chairs; and 15 chairs including large institutional offices. Available cost data do not
differentiate between 3 to 5 chair offices and 6 chair offices, therefore the initial installation costs
are the same for both sets of offices. EPA completed these calculations in the MS Excel® file,
Amalgam Sep Installation Costs (U.S. EPA, 2016b). Separator purchase and installation costs
were converted to 2016 dollars using RS Means Historic Cost Indexes. Table 9-2 presents the
amalgam separator purchase costs (one-time capital costs) and installation costs that EPA
calculated for each model dental office without an amalgam separator already in place.
Table 9-2. Summary of One-time Incremental Compliance Costs ($2016) to Model Dental
Offices to Initially Purchase and Install Amalgam Separators
Cost Element
Number of chairs in the model dental office
lor 2
3,4, or 5
6
7 to 14
15
Separator Purchase
$437
$697
$1,058
$1,291
$2,424
Initial Separator
Installation
$235
$276
$276
$358
$942
TOTAL
$672
$973
$1,334
$1,649
$3,366
Source: U.S. EPA, 2016c.
Some existing dental offices have already installed amalgam separators, either voluntarily
or to comply with state or local requirements; see Chapter 6 of this document for more details.
Under the final rule, such dental offices may continue to operate their existing amalgam
separators for the remaining useful lifetime of the separator (or ten years, whichever comes first).
Therefore, EPA did not include the initial costs for offices with amalgam separators currently in
place to purchase and install another amalgam separator. The dental discharger must still comply
with the other final rule requirements including the specified BMPs, operation and maintenance,
reporting, and recordkeeping requirements. The compliance costs for these requirements is
described in the Chapters 9.1.2.2 and 9.1.2.3.
In assessing the long term costs of rule compliance, available data indicate amalgam
separators have a typical service life of at least 10 years, at which time the amalgam separators
would need to be replaced (Vandeven and McGinnis, 2005). Consequently, for purposes of the
economic analysis, in order to calculate annualized costs EPA assumes a 10-year life span of the
separator. For offices with amalgam separators currently in place, the cost methodology also
includes costs to install a new separator 10 years after the effective date of the rule as described
above. Therefore, for the purposes of estimating compliance costs, EPA assumed all offices
would incur the cost of installing a new amalgam separator no later than 10 years after the
effective date of this rule. The separator cost was calculated using the purchase information in
Table 9-2 as described above.
To assess the installation costs of the replacement separator at all dental offices, EPA
assumes the major plumbing modifications needed by the office for initial amalgam separator
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Chapter 9—Costs of Technologies
installation would have already been completed. However, separator models may change and/or
the plumbing needs may be slightly different. Therefore, EPA projected the installation costs for
subsequent amalgam separators would be one-half of the cost of the original installation cost
shown in Table 9-2. To the extent dental offices either close (discontinue operating) or certify
they no longer remove or place amalgam, these costs are likely overstated.
One-Time Compliance Report
To calculate costs for dental offices to comply with the One-Time Compliance Report
requirements in the final rule, EPA calculated a burden estimate as shown in Table 9-3. The rule
requires submission of this report once per dental office; see § 441.50(a).
Table 9-3. Burden Estimate for One-time Compliance Report
Task
Time (minutes)
Read Instructions
3
Dental Practice and Address
1
Part I: Facility Information
2
Part II: Amalgam Handling
45
Obtain Signature
10
Submit to Control Authority
15
Total
76
EPA used the same reporting burden estimate for dentists that do not place any amalgam,
and that only remove amalgam in limited emergency or unplanned, unanticipated circumstances.
Although the actual time for these dental offices to complete the report is most likely less than
dental offices that place or remove amalgam, EPA used the same value as a higher and therefore
conservative cost estimate. These are the only costs such dental offices are expected to incur.
EPA assumed that a dental assistant, at a labor rate of $17.75 per hour (Bureau of Labor
Statistics, 2015), would complete the reporting form. EPA also included the cost of postage
($0.49) for submitting the report. See Table 9-4 for the reporting costs for each model dental
office. As shown, EPA estimated the one-time reporting cost to be $23. EPA included costs for
all dental offices subject to the rule associated with a One-Time Compliance Report.
Table 9-4. Summary of One-Time Compliance Report Costs ($2016)
to Model Dental Offices
Cost Element
Number of chairs in the model dental office
lor 2
3,4, or 5
6
7 to 14
15+
One-Time Compliance
Report
$23
$23
$23
$23
$23
Source: U.S. EPA, 2016c.
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Chapter 9—Costs of Technologies
9.1.2.2 Annual Costs for Dental Offices
Dental Offices without Amalgam Separators
Annual costs include replacement of the amalgam retaining unit (e.g., canister, cartridge,
or filter); amalgam separator inspection costs; separator maintenance/cleaning costs, amalgam
recycling preparation; and annual amalgam recycling costs. Each of these costs are detailed
below.
•	Replacement of the amalsam-retainins unit. For purposes of the cost model,
replacement costs were calculated as the average of the amalgam separators
appropriate for each group of model dental offices (i.e., based on the number of chairs
in the office). The replacement cost of each type and size of amalgam separator is in
Table 9-1, and the model dental office is described in Chapter 9.1.1. The average
cost for each model dental office is in Table 9-6.
•	Recycling Service: The rule requires that the amalgam retaining unit must be replaced
in accordance with the manufacturer's schedule, or whenever the collection of
retained solids reaches 95 percent of the manufacturer's stated design capacity, or
annually, whichever comes first. See § 441.30 (a)(l)(vi). EPA included costs for
dental offices to recycle the collected amalgam. As shown in Table 9-1, recycling
cost vary from $0 (some vendors include recycling costs as part of the original
purchase cost and/or replacement part cost) to $580 per recycling event. Where
manufacturer recommendations for exchanging the canister or other amalgam
retaining unit are not annual, the costs were pro-rated to an annual basis. See
"Supporting Data for the Costing Analysis" (U.S. EPA, 2016d) and Chapter 16 for
more details. For purposes of estimating national costs of this requirement, the
average cost of annual recycling as reported for each separator is $82 (in 2016
dollars).
EPA included the following as annual O&M costs: inspection (assume monthly),
separator maintenance (assume biweekly), and amalgam recycling preparation, as explained
below:
•	Inspection'. The final rule requires the separator to be inspected in accordance with
the manufacturer's operation manual; EPA assumed a monthly inspection for
purposes of costing. Costs include a dental assistant ($17.75/hour) to perform a five-
minute visual inspection monthly. This cost is included for all of the model dental
offices.
•	Maintenance: The final rule requires the separator to be maintained. This annual cost
reflects costs to the dental office for maintenance activities that are beyond the cost of
visual inspections and the replacement of the amalgam retaining unit. This cost also
reflects the wide range of vendor cost data, and also includes contingency for
unforeseen costs. For example, the amalgam retaining unit may need service or
replacement more frequently than the manufacturer's minimum recommended change
frequency, and other maintenance activities may include additional visual checks of
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Chapter 9—Costs of Technologies
the system such as checking the fill line when the unit does not have an audible
alarm. For costing purposes, EPA assumed such maintenance would be performed by
a dental assistant every two weeks and that each maintenance session would take 15
minutes (on average).
•	Recycling preparation: As described above, EPA included annual costs for recycling
the solids collectors and/or filters/cartridges by pro-rating each separator's
recommended recycle frequency to a 12 month periodicity. Recycle preparation
includes costs for a dental assistant ($17.75/hour) to spend 15 minutes to prepare the
materials for shipping and recycling. Based on the typical recycling frequency of
separators in Table 9-1, EPA assumes recycling occurs an average of two times per
year. Therefore, the annual cost of recycle preparation is $9.
•	Vacuum system operation and maintenance cost off-set. EPA included a negative
incremental cost (cost off-set) associated with less frequent replacement and servicing
of the existing vacuum system filter and impeller blade following installation of an
amalgam separator. Over time, solid particulates (or abrasives) in the water passing
through the wet vacuum system can cause the system to fail. Approximately 80
percent of dental offices use wet vacuum systems. As an alternative to replacing the
wet vacuum system, dentists have maintenance performed on the vacuum (e.g.,
cleaning, repair, motor replacement). EPA included the cost offset for the decreased
labor needed to maintain the vacuum system as a result of amalgam separator
installation. Table 9-5 presents a comparison of the maintenance labor costs at a
dental office with no amalgam separator in place and a dental office with an amalgam
separator in place. Over a ten-year period, EPA expects the model dental office to
have an annualized costs savings of approximately $75 per year (U.S. EPA, 2016d).
Table 9-5. Vacuum System Labor Cost Offset for Model Dental Offices Purchasing and
Installing Amalgam Separators
Year
Maintenance Activity
(Labor Rate: $150 per hour)
No
Amalgam
Separator
With an
Amalgam
Separator
0
Vacuum System Maintenance: 4 hours at labor rate of $150 per hour
$600
$600
3
For systems without amalgam separator, maintenance during year 3
$600
$0
5
For systems with amalgam separator, minor maintenance visit (1.5-
hour visit)
$0
$225
6
For systems without amalgam separator, maintenance during year 6
$600
$0
9
For svstems without amalgam separator, maintenance during vear 9
$600
$0
10
Vacuum System Maintenance: 4 hours at labor rate of $150 per hour
$0
$600
10-year Total Maintenance Cost
$2,400
$1,425
10-year Cost Offset

$975
Annualized Cost Offset

$98
Annualized Cost Offset for Model Dental Office (accounts for 80% of
dental offices using wet vacuum system)

$78
(~$75 per year)
Source: U.S. EPA, 2016d.
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Chapter 9—Costs of Technologies
EPA does not project incremental compliance costs associated with the two BMPs
required at § 441.30(b) because costs for non-oxidizing, pH neutral line cleaners are roughly
equivalent to other line cleaners, and dental offices will not incur additional costs by changing
the location for flushing waste amalgam.
Table 9-6 presents the annual costs for each of the components identified in this chapter.
EPA converted replacement parts and recycling service costs to 2016 dollars using RS Means
Historical Indexes. Costs are presented for each group of chair sizes that corresponds to one of
EPA's model dental offices.
Table 9-6. Summary of Annual Costs ($2016) to Model Dental Offices Purchasing and
Installing Amalgam Separators
Cost Element
Number of chairs in the model dental office
lor 2
3,4, or 5
6
7 to 14
15
Replacement Parts3
$275
$386
$559
$732
$1,078
Cost Offset for Vacuum
System Maintenance
-$75
-$75
-$75
-$75
-$75
Visual Inspection
(assumed Monthly)
$18
$18
$18
$18
$18
Separator Maintenance
(assumed Biweekly)
$115
$115
$115
$115
$115
Recycling Preparation
$9
$9
$9
$9
$9
Recycling Service3
$82
$82
$82
$82
$82
TOTALb
$424
$535
$708
$881
$1,227
Source: U.S. EPA, 2016c.
a - Replacement parts and recycling service costs converted to 2016 dollars using RS Means Historical Indexes,
b - Total for each model office size may not equal summation of individual costs presented due to rounding.
Dental Offices with Amalgam Separators
For dental offices that already have an amalgam separator, EPA included incremental
costs for the same components described above for dental offices without amalgam separators:
replacement of the amalgam retaining unit (e.g., canister, cartridge, or filter) if not already
completed at least once per year; amalgam separator inspection costs; separator
maintenance/cleaning costs; amalgam recycling preparation; and annual amalgam recycling
costs. Offices that already have amalgam separators in place are already incurring the majority of
these costs irrespective of this final rule. As such, for those components EPA calculated the
incremental costs as a portion (percentage) of the annual costs incurred by dental offices without
separator technology in place. More specifically, the incremental annual costs for those
components for offices with amalgam separators are assumed to cost 50 percent of what the costs
of these components are to an office that does not already have an amalgam separator. This is
likely an overestimate of costs because state and local programs have largely reported successful
implementation of requirements to install amalgam separators; see Chapter 6. Table 9-7 presents
the annual incremental compliance costs that EPA calculated for the final rule for dental offices
with an amalgam separator in place. Note that for inspection, EPA included the same costs for
offices with and without separators because most state and local dental amalgam programs do
not have such requirements, and EPA did not identify any data supporting a different approach.
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Chapter 9—Costs of Technologies
EPA did not include the vacuum system operation and maintenance cost off-set because dental
offices with amalgam separators already benefit from reduced vacuum repair as a result of the
separator installation.
Table 9-7. Summary of Annual Costs ($2016) to Model Dental Offices with an Amalgam
Separator in Place
Cost Element
Fraction of Cost
Compared to
Offices without
Amalgam
Separators
Number of chairs in the model dental office
1 or 2
3,4, or 5
6
7 to 14
15
Replacement Parts3
50%
$138
$193
$280
$366
$539
Visual Inspection
(assumed Monthly)
100%
$18
$18
$18
$18
$18
Separator Maintenance
(assumed Biweekly)
50%
$58
$58
$58
$58
$58
Recycling Preparation
50%
$4.44
$4.44
$4.44
$4.44
$4.44
Recycling Service3
50%
$41
$41
$41
$41
$41
TOTALb

$258
$314
$400
$487
$660
Source: U.S. EPA, 2016c.
a - Replacement parts and recycling service costs converted to 2016 dollars using RS Means Historical Indexes,
b - Total for each model office size may not equal summation of individual costs presented due to rounding.
9.1.2.3 Recordkeeping Costs
The final rule includes recordkeeping requirements that all dental offices, or an agent or
representative of the dental office, will need to maintain: inspections, amalgam retaining unit
replacement, amalgam recycling/disposal, separator maintenance, and records of repair and
separator service. Costs associated with these recordkeeping requirements are detailed in this
subchapter. EPA calculated recordkeeping costs using the following parameters:
•	Inspection: EPA included costs for a dental assistant ($17.75/hour) to complete the
documentation for required inspections, estimating it would take five minutes per
month per inspection.
•	Maintenance: EPA included costs for a dental assistant ($17.75/hour) to complete the
documentation for maintenance, estimating it would take five minutes each
occurrence. EPA assumed maintenance would occur every two weeks.
•	Recycling service: EPA included costs for a dental assistant ($17.75/hour) to
complete the documentation for recycling service, estimating it would take five
minutes each occurrence. EPA assumed recycling services would occur annually.
EPA also estimated periodic reporting costs.
•	Transfers Ownership: If a dental discharger transfers ownership of the facility, the
new owner must submit a new One-Time Compliance Report to the Control
Authority no later than 90 days after the transfer; see § 441.50(a)(4). These costs are
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Chapter 9—Costs of Technologies
assumed to incur at 10 percent of the dental offices when there is a transfer in
ownership of the dental office. Since the form is the same, EPA used the same cost
used for the initial One-Time Compliance Report ($23) described above in Chapter
9.1.2.1.
• Separator repair: As part of the final rule, dental offices must have amalgam
separators repaired in the event they discover the unit is malfunctioning. For purposes
of the cost analysis, EPA assumed the dental office will either be under a warranty
program or will have a contract in place with the separator manufacturer to repair any
malfunctioning amalgam separators. EPA included costs to the dental office for a
dental assistant ($17.75/hour) to spend a total of 30 minutes to contact a repair
person, oversee their work at the office, and document the repair (recordkeeping).
Because of this recordkeeping component, EPA included the costs under periodic
costs. Not all offices will need to have repairs occur each year. Vendors indicated that
separators are primarily constructed of heavy duty plastic and have no moving parts,
therefore repairs are infrequent. Based on vendor observations that separators rarely
malfunction, EPA conservatively estimates one percent of offices would incur this
cost annually ($17.75/hour x 0.5 hours x 1 percent).
Table 9-8 presents the annual recordkeeping costs that EPA calculated for dental offices
to comply with the final rule. These costs apply to both dental offices without amalgam
separators in place and dental offices with amalgam separators.
Table 9-8. Summary of Annual
Recordkeeping Costs ($2016) to Model Dental Offices
Cost Element
Number of chairs in the model dental office
lor 2
3,4, or 5
6
7 to 14
15
Recordkeeping: Visual
Inspection
$18
$18
$18
$18
$18
Recordkeeping: Separator
Maintenance
$38
$38
$38
$38
$38
Recordkeeping: Recycling
$2.96
$2.96
$2.96
$2.96
$2.96
Periodic Recordkeeping Costs
One-Time Compliance
Report (transfer of
ownership)
$2.30
$2.30
$2.30
$2.30
$2.30
Separator Repair
$0.09
$0.09
$0.09
$0.09
$0.09
TOTAL3
$62
$62
$62
$62
$62
Source: U.S. EPA, 2016c.
a - Total for each model office size may not equal summation of individual costs presented due to rounding.
9.2 References
ADA (American Dental Association). 2007. ADA Professional Product Review. Document
Control Number (DCN) DA00043.
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Chapter 9—Costs of Technologies
Behm, D. 2008. Dentists Filtering Out Mercury but Nearly One-fifth Miss MMSD Deadline.
Milwaukee Journal Sentinel. February 9. DCN DA00203.
Bureau of Labor Statistics. 2015. Occupational Employment and Wages for Dental Assistants.
May. DCN DA00476.
ERG (Eastern Research Group). 2010. SolmeteX meeting minutes for 15 December 2010.
Chantilly, VA. DCN DA00081.
ERG and SolmeteX. 2011. Notes from telephone conversation between Kimberly Landick, ERG
and SolmeteX, May 10, 2011: Subject Polishing System for Removing Dissolved
Mercury. DCN DA00120.
ERG and American Dental Accessories. 2011. Email correspondence between Kimberly
Landick, ERG, and American Dental Accessories, February 28, 2011: Subject Request
for Amalgam Separator Information. DCN DA00061.
ERG and DRNA. 2011. Notes from telephone conversation between Kimberly Landick, ERG,
and Marc Sussman and Darwin Moreira, DRNA, March 1, 2011: Subject Amalgam
Separator Questions. DCN DA00062.
King County. 2005. Fact Sheet: Discharging Dental Wastewater into the King County Sewer.
Department of Natural Resources and Parks. DCN DA00291.
McManus, K.R., and P.L. Fan. 2003. Purchasing, Installing and Operating Dental Amalgam
Separators. Journal of the American Dental Association, 134:1054-1065. DCN
DA00162.
MCES (Metropolitan Council Environmental Services). 2009. Revised - Features of Approved
Amalgam Separators. March. DCN DA00070.
MMSD (Madison Metropolitan Sewerage District) and University of Wisconsin Extension.
2006. Amalgam Management for Dental Offices. Milwaukee, WI. DCN DA00232.
National Maternal & Child Oral Health Resource Center. 2011. Safety Net Dental Clinic
Manual: Clinic Management, http://dentalclinicmanual.eom/chapt6/3 6.html#opperdent.
DCN DA00143.
NH. 2015. New Hampshire Approved Amalgam Separators - Updated September 2015. DCN
DA00474.
Pure Water Development. 2016. Pure Water Development ECO II Features (website).
http://www.ecotwo.com/About the ECO II/bfl3426d/l/The features.aspx. Accessed
July. DCN DA00484.
R&D Services. 2016. The Amalgam Collector: Pricing and How to Order (website).
http://theamalgamcollector.com/price.htm. Accessed July. DCN DA00473.
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Chapter 9—Costs of Technologies
Rebec Environmental. 2016 Amalgam Separators (website).
http://rebecenvironmental.com/products/amalgam-separatorsA Accessed July. DCN
DA00472.
SF Environment. 2005. San Francisco Department of the Environment. San Francisco City and
County List of Approved Amalgam Separators. March. DCN DA00077.
Solmetex. 2016. Hg 5 Amalgam Separators (website), http://www.solmetex.com/hg5-series-
products/. Accessed July 2016. DCN DA00485.
U.S. Air Force. 2011. Synopsis of Dental Amalgam Separators. January 24. Dental Evaluation
and Consultation Service. DCN DA00079.
U.S. EPA. 2003. Options for Dental Mercury Reduction Programs: Information for
State Provincial and Local Governments. A Report of the Bi national Toxics Strategy
Mercury Workgroup Co-Chairs. (December 16). DCN DA00003.
U.S. EPA 2016a. Amalgam Separator Cost Breakdown by Chair Size. MS Excel® file. Office of
Water. Washington, DC. December. DCN DA00454.
U.S. EPA. 2016b. Amalgam Separator Installation Costs. MS Excel® file. Office of Water.
Washington, DC. December. DCN DA00455.
U.S. EPA. 2016c. Dental Office Cost Calculations. MS Excel® file. Office of Water.
Washington, DC. December. DCN DA00456.
U.S. EPA. 2016d. Supporting Data for the Costing Analysis. Memorandum to the Public Record
for the Dental Category Final Rule. Office of Water. Washington, DC. December. DCN
DA00471.
Vandeven, J., and S. McGinnis. 2005. An Assessment of Mercury in the Form of Amalgam in
Dental Wastewater in the United States. Water, Air and Soil Pollution, 164:349-366.
DCN DA00163.
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Chapter 10—Error! Reference source not found.
Chapter 10
Economic Impacts for the Dental Industry	
This chapter describes EPA's economic impact assessment of the dental category rule,
and is organized as follows:
•	Chapter 10.1 reviews the structure of the regulated sector in terms of number of
dental offices potentially subject to the dental category rule and the distribution of
these offices by revenue.
•	Chapter 10.2 presents the compliance costs that EPA expects will be incurred by
dental offices under the rule, and combines the estimates of numbers of offices
subject to the rule by relevant operating characteristics to estimate total nationwide
compliance costs for the rule.
•	Chapter 10.3 summarizes the methods and results of several tests of the economic
impacts of the rule.
•	Chapter 10.4 assesses the social cost of the dental category rule, including costs to
dental offices28 and the costs to permitting authorities for administering rule
requirements.
•	Chapter 10.5 determines the potential for significant economic impact on small dental
office entities as a result of the rule.
•	Chapter 10.6 provides references for this chapter.
10.1 Overview Of Dental Offices Potentially Subject To Final Regulation
In this chapter, EPA reviews its estimate of the number of dental offices that might be
subject to the rule, including:
•	A review of information from the Economic Census and other sources on the number
of offices in the dental sector.
•	Adjustments to these counts to reflect baseline levels of (1) number of dental offices
using mercury-containing materials (dental amalgam); (2) the number of dental
offices that currently use treatment technology; and (3) as a result, the costs likely to
be incurred by dental offices in complying with the rule.
28 As explained in Chapter 2, dental offices include but are not limited to large institutions such as dental schools
and clinics; permanent or temporary offices, home offices, and facilities; and including dental offices owned and
operated by federal, state, or local governments including military bases.
10-1
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Chapter 10—Error! Reference source not found.
10.1.1 Number of Dental Offices Potentially Subject to the Final Regulation
To support the assessment of total costs and economic impact of the final dental category
rule, EPA relied on data from the 2012 Economic Census describing the number of firms and
establishments in the dental office sector (NAICS 621210), and their annual receipts/revenue
(U.S. Census Bureau, 2012a). EPA used the 2012 Census data for this analysis because these
data are the most recent comprehensive public data on the dental office sector. Data on the
number of dental office firms and establishments by revenue size are used to assess the number
of regulated entities that may incur costs, the costs that these entities may incur (based on their
scale of business operations and associated need for compliance technology), and thus the rule's
total cost. These data are also used to assess the potential impact of a regulation in terms of the
level of costs that may be incurred by individual firms/establishments and whether these costs
would be unduly burdensome in relation to their ongoing revenue.
EPA determined that the operating characteristics of the individual dental offices — in
particular, the number of dental chairs in the office — would be a key determinant of the
technology response and associated compliance costs that would be incurred by dental offices in
complying with the final dental category rule. Therefore, EPA estimated compliance costs for
each dental office size. In addition, in reviewing 2012 Economic Census data for the dental
office sector (U.S. Census Bureau, 2012b), EPA observed that almost all firms are single-
establishment/single-office firms. The total of 133,221 establishments/offices is owned by
125,275 firms — thus no more than 10,557 offices, or fewer than 8 percent of offices, can be
owned by multi-office firms. And only at the highest revenue ranges do firms frequently own
and operate more than one office. Thus, as a practical matter, there is little difference between
the number of dental offices and the number of dental firms. For this reason, EPA performed the
impact analysis at the level of the office instead of the level of the firm.
Starting with the 2012 Economic Census counts of dental offices (U.S. Census Bureau,
2012a), EPA applied a number of adjustments to estimate the number of dental offices, in
aggregate and by revenue range, that could be subject to the final Dental Amalgam Rule.
•	As shown in Table 10-1, the Economic Census listed 133,221 dental offices in total.
In addition, office counts are spread over 11 revenue ranges, ranging from the lowest
range, $0-$10,000, to the highest range, $10,000,000 and up, based on 2012 dollars.
EPA performed its cost and economic impact analysis based on 2016 dollar values.
Because the Economic Census revenue ranges are defined in 2012 dollars, EPA
adjusted these dollar values defining the revenue ranges to 2016 dollars using the
GDP Deflator, a sector-/commodity-neutral basis for adjusting dollar values for
general inflation over time. Table 10-1 lists the revenue range values in 2012 and
2016 dollars in the left set of columns of the table. This adjustment assumes that
dental service prices matched the general rate of inflation over the 2012-2016 period,
and that the industry remained constant in all other regards: total quantity of services
provided and total number and distribution of offices by revenue range.
•	Of the 133,221 total offices, the Economic Census reported 122,926 offices as being
in business for the full 2012 year and 10,295 offices as being in business for only part
of the year. The numbers of dental offices listed in the 11 revenue ranges represent
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the 122,926 offices that were in business for the full year. Because the revenue range
of offices is important in estimating the compliance requirements that an individual
office would face, and also for assessing small entity impacts, EPA assigned the
remaining 10,295 offices (those in business for only part of the year) across the
revenue ranges of offices that were in business for the full year, in the same
proportion as the full year offices. EPA assigned these partial-year offices to the small
business revenue ranges (the first nine ranges) to prevent potentially understating the
number of small businesses that could incur costs as a result of the final dental
category rule. The tenth revenue range includes the Small Business Administration
revenue cutoff ($7.5 million), and EPA assigned none of the partial-year offices to
this range.29 The right-most column in Table 10-1 reports the numbers of offices by
revenue range after this adjustment.
Table 10-1. Dental Office Establishments by
Revenue Range (NAICS 621210, Offices of Dentists)
Revenue Ranges($2012)
Revenue Ranges($2016)
Number
Establishments
Adjusted Number
Establishments3
Low
High
Low
High
0
$10,000
$0
$10,491
58
63
$10,000
$24,999
$10,492
$26,228
456
494
$25,000
$49,999
$26,229
$52,458
1,139
1,235
$50,000
$99,999
$52,459
$104,917
2,983
3,234
$100,000
$249,999
$104,918
$262,293
14,217
15,413
$250,000
$499,999
$262,294
$524,587
28,736
31,153
$500,000
$999,999
$524,588
$1,049,175
42,337
45,899
$1,000,000
$2,499,999
$1,049,176
$2,622,939
28,495
30,892
$2,500,000
$4,999,999
$2,622,940
$5,245,879
3,958
4,291
$5,000,000b
$9,999,999
$5,245,880
$10,491,759
474
474
$10,000,000
Or more
$10,491,760
Or more
73
73
Establishments operated for the entire year
122,926
133,221
Establishments not operated for the entire year
10,295
-
Total Establishments
133,221
133,221
Sources: U.S. Census Bureau, 2012a, U.S. EPA, 2016a
a - With establishments not operating for the entire year assigned to first nine revenue ranges,
b - Highlighting in the $5 million to $10 million revenue range indicates that this range contains the SB A small
business size standard for offices of dentists.
In addition to the dental offices that are reported in the Economic Census, EPA estimates
that dental services potentially within the scope of this regulation are performed at an additional
415 large institutional dental offices, including 65 dental schools and 350 military clinics (EPA-
HQ-OW-2014-0693-0329). Adding these large offices to the 133,221 dental offices from the
Economic Census brings the total of dental offices that are potentially subject to the rule to
133,636.
29 See discussion in Chapter 10.5 for information on the assessment of small entity impacts.
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10.1.2 Adjustments to Account for Baseline Status
EPA accounted for additional factors that will influence the extent to which dental office
sector would incur costs under the dental category rule.
•	First, EPA recognized that certain specialty dental practices do not place or remove
dental amalgam (see Chapter 4.2) and thus did not include them in the scope of the
final rule. These specialty practices are: oral pathology, oral and maxillofacial
radiology, oral and maxillofacial surgery, orthodontics, periodontics, and
prosthodontics. Based on information from the American Dental Association (ADA),
EPA estimated that 21 percent of total dental offices are specialty service practices
(ADA, 2016). EPA assumed that, within specialty practices, only endodontists,
pediatric dentists, and endodontists place or remove amalgam (Vandeven and
McGinnis, 2005), or approximately 39.4 percent of specialty practices (based on data
from ADA, 2016). As a result, EPA estimated that approximately 13 percent30 of
non-military dental offices are specialists that are not subject to the rule. Because the
rule will not apply to them, EPA assigned no compliance-related costs to these 16,916
offices, and these offices are not included in the impacts analysis. This leaves 116,720
offices that are subject to the final rule.
•	Second, based on information from U.S. EPA, 2016b, EPA assumes that all 350
military clinics already have amalgam separators in place.
•	Third, EPA divided the non-military offices subject to the rule into two groups: (1)
offices that have already installed amalgam separators and (2) offices without
amalgam separators. Offices with amalgam separators already in place will incur
lower costs relative to offices without treatment technology in place. EPA reviewed
state and local requirements and estimated that 41 percent of offices have amalgam
separators in place already (U.S. EPA, 2016c). EPA used this percentage to
categorize all non-military offices as either "technology in place" or "no technology-
in-place" offices. Using this approach, EPA categorized 47,942 offices as having
technology-in-place, and the remaining 68,428 as no technology-in-place.
•	Fourth, among the remaining offices subject to the rule that have not already installed
amalgam separators, EPA estimated that approximately 20 percent do not place or
remove dental amalgam (Pimpare, 2012) and thus would incur no treatment
technology-related costs due to the dental category rule. These 13,686 offices would
need to certify to their permitting authority that they do not process amalgam, for
which the offices would incur a one-time only reporting cost.
Table 10-2 lists the numbers of dental offices by revenue range (from Table 10-1), and
including large offices, with these further breakouts. EPA carried these estimated numbers of
30 21 percent (share of non-military offices that are specialty) times 61 percent (share of specialty offices do not
place amalgam).
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dental offices by baseline amalgam use and compliance status forward to the cost and economic
impact analysis.
Table 10-2. Establishments Assigned to Regulation Analysis Category


Number Establishments
Revenue Range (2016$)a

Specialty
Offices Not
Offices Subject to the Rule





No Tech in Place
Low
High
All
Officesb
Subject to
Rule0
Military
Clinics'1
Tech-in-
Placee
Using
Amalgam
Not Using
Amalgam'
$0
$10,491
63
8
0
23
26
6
$10,492
$26,228
494
63
0
178
203
51
$26,229
$52,458
1,235
157
0
444
507
127
$52,459
$104,917
3,234
410
0
1,163
1,328
332
$104,918
$262,293
15,413
1,956
0
5,544
6,330
1,583
$262,294
$524,587
31,153
3,954
0
11,206
12,795
3,199
$524,588
$1,049,175
45,899
5,825
0
16,509
18,851
4,713
$1,049,176
$2,622,939
30,892
3,921
0
11,112
12,688
3,172
$2,622,940
$5,245,879
4,291
545
0
1,543
1,762
441
$5,245,880
$10,491,759
474
60
0
170
195
49
$10,491,760
$100,000,000
73
9
0
26
30
7
Dental schools/military clinics
415
8
350
23
27
7
Total
133,636
16,916
350
47,492
54,742
13,686
Source: U.S. EPA, 2016a
a - See Table 10-1.
b - See Table 10-1 for number of offices by revenue range.
c - Based on 21 percent of non-military offices being specialty and 61 percent of specialty offices not placing or
removing any amalgam (ADA, 2016), or 12.69% of all non-military offices,
d - Number of military clinics based on EPA-HQ-OW-2014-0693-0329.
e - Based on a review of state and local separator programs and voluntary installation in locations without existing
requirements (U.S. EPA, 2016c).
f - Based on assumption that 20% of dentists without existing separators in place do not place or remove amalgam
(Pimpare, 2012).
10.2 Summary Of The Final Regulation And Compliance Costs
EPA developed national cost estimates for dental offices to purchase and install amalgam
separators, maintain the separators (combination of annual part/supply costs and labor costs),
recycle the dental amalgam waste, and comply with inspection and reporting requirements. EPA
prepared the costs to the industry of implementing the rule, taking into account any dental
amalgam control practices that are currently mandated by state and local pretreatment programs.
EPA assumed there would be no increased costs to dental offices to implement the two best
management practices (BMPs) in the rule.
10.2.1 Summary of Compliance Costs
Using the methodology described in Chapter 9, EPA developed compliance costs for
model offices with and without amalgam separators. As described in Chapter 9, EPA assumed
that offices with treatment-in-place would incur no cost for purchasing and installing compliance
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technology at the time of initial regulatory compliance. However, EPA estimated additional
permit-related costs and some recurring incremental costs (i.e., annual and one-time costs) for
such offices.
EPA developed compliance costs based on the number of dental chairs in an office, as
discussed in Chapter 9.1. The number of operatory chairs is the key driver of cost because the
treatment capacity, and thus cost, of amalgam separators is based on the number of chairs
serviced by the separator. Accordingly, EPA estimated costs for these cost categories based on
the numbers of chairs in an office, organized within number-of-chair ranges, as follows:
•	1 to 2 chairs;	• 4 chairs;	• 6 chairs; and
•	3 chairs;	• 5 chairs;	• 7 to 14 chairs.
EPA also estimated costs for dental schools and military clinics. For purposes of costs,
EPA assumed that average dental schools and military clinics have 15 chairs.
Table 10-3 and Table 10-4 list estimated compliance costs for no-technology-in-place
offices and technology-in-place offices, respectively, in 2016 dollars, by cost category and by
size (i.e., number of chairs).
Table 10-3. Dental Office Compliance Costs by Number of Chairs, Offices with No
Technology in Place (2016$)
Cost Element
Operating Size: Number of Chairs
1-2
3
4
5
6
7-14
15
Technology Installation and Other Startup Costs
Equipment purchase
$437
$697
$697
$697
$1,058
$1,291
$2,424
Installation
$235
$276
$276
$276
$276
$358
$942
One-Time Compliance
Report
$23
$23
$23
$23
$23
$23
$23
Annual Costs
Replacement parts
$275
$386
$386
$386
$559
$732
$1,078
Separator maintenance
$115
$115
$115
$115
$115
$115
$115
Maintenance-related
recordkeeping
$38
$38
$38
$38
$38
$38
$38
Recycling preparation
$9
$9
$9
$9
$9
$9
$9
Recycling service
$82
$82
$82
$82
$82
$82
$82
Recycling-related
recordkeeping
$3
$3
$3
$3
$3
$3
$3
Visual Inspection
$18
$18
$18
$18
$18
$18
$18
Inspection-related
recordkeeping
$18
$18
$18
$18
$18
$18
$18
Vacuum filter/impeller blade
cost savings
-$75
-$75
-$75
-$75
-$75
-$75
-$75
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Table 10-3. Dental Office Compliance Costs by Number of Chairs, Offices with No
Technology in Place (2016$)
Cost Element
Operating Size: Number of Chairs
1-2
3
4
5
6
7-14
15
Periodic Costs3
Change form (10% of
offices)
$23
$23
$23
$23
$23
$23
$23
Repair-related recordkeeping
(1% of offices)
$9
$9
$9
$9
$9
$9
$9
Source: U.S. EPA, 2016a; U.S. EPA, 2016c
a - EPA multiplies these periodic costs by the percentage when calculating annual costs (i.e., change form is
$23*. 10 = $2.3 and repair-related recordkeeping is $9*.01=$0.09, as shown in Chapter 9)
Table 10-4. Dental Office Compliance Costs by Number of Chairs, Offices with
Technology in Place (2016$)
Cost Element
Operating Size: Number of Chairs
1-2
3
4
5
6
7-14
15
Technology Installation and Other Startup Costs
Equipment purchase
$0
$0
$0
$0
$0
$0
$0
Installation
$0
$0
$0
$0
$0
$0
$0
One-Time Compliance
Report
$23
$23
$23
$23
$23
$23
$23
Annual Costs
Replacement parts
$138
$193
$193
$193
$280
$366
$539
Separator maintenance
$58
$58
$58
$58
$58
$58
$58
Maintenance-related
recordkeeping
$38
$38
$38
$38
$38
$38
$38
Recycling preparation
$4
$4
$4
$4
$4
$4
$4
Recycling service
$41
$41
$41
$41
$41
$41
$41
Recycling-related
recordkeeping
$3
$3
$3
$3
$3
$3
$3
Visual Inspection
$18
$18
$18
$18
$18
$18
$18
Inspection-related
recordkeeping
$18
$18
$18
$18
$18
$18
$18
Vacuum filter/impeller blade
cost savings
$0
$0
$0
$0
$0
$0
$0
Periodic Costs"
Change form (10% of
offices)
$23
$23
$23
$23
$23
$23
$23
Repair-related recordkeeping
(1% of offices)
$9
$9
$9
$9
$9
$9
$9
Source: U.S. EPA, 2016a, U.S. EPA, 2016c
a - EPA multiplies these periodic costs by the percentage when calculating annual costs (i.e., change form is
$23*. 10 = $2.3 and repair-related recordkeeping is $9*.01=$0.09, as shown in Chapter 9)
In assessing the costs of compliance, EPA estimated that amalgam separator equipment
would have a service life of 10 years, after which time the compliance equipment would need to
be replaced. For the estimation of reinstallation costs, EPA assumed that offices, regardless of
original technology-in-place status, would incur the full cost of purchasing compliance
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equipment at the time of technology reinstallation. However, because various modifications
needed for equipment installation would have been completed during initial installation, EPA
estimated, for reinstallation, that compliance equipment would be able to be installed at one-half
the cost of the original installation. Further, EPA assumed that, after re-installation, dental
offices would incur ongoing expenses in the same way as described in the preceding paragraphs
and shown in Table 10-3 and Table 10-4.
To summarize, EPA accounted for the initial installation and re-installation requirement
by building up costs, as described, for two separate analysis periods:
1.	Years 1-10.31 In this period, dental offices that place or remove amalgam and have
no-technology-in-place are assumed to install compliance equipment, if needed, and
incur other startup costs at the beginning of year 1. Recurring costs are then incurred,
as described above, in years 1-10.
2.	Years 11-20. In this period, all dental offices that place or remove amalgam are
assumed to incur the cost of reinstalling compliance equipment at the beginning of
year 11. Recurring costs are then incurred, as described, in years 11-20.
For the assessment of compliance costs to dental offices, EPA accumulated these costs on
a present value basis at year 1 at a discount rate of 7 percent, which is intended to represent the
opportunity cost of capital to society, on a pre-tax, constant dollar basis.32 The resulting present
value is then annualized over the full 20-year analysis period at the 7 percent interest rate. EPA
used the resulting total annualized compliance costs in assessing the total estimated cost and
impact of the rule to dental offices, as described in subsequent chapters. Table 10-3 and Table
10-5 report specific elements of compliance costs and summarize the tabulation of costs to
develop estimates of the total annualized compliance cost to dental offices.
For no-technology-in-place and technology-in-place offices, Table 10-5 and Table 10-6,
respectively, summarize the tallying of these costs according to the initial installation and
reinstallation specifications, and present value and annualized cost calculations. For each
installation event, the table reports the total initial outlay and annually recurring costs, as
incurred, and then summarizes the tabulation of these costs on a present value basis. Initial
technology installation costs are directly tabulated at the beginning of year 1 (the year of initial
compliance), while reinstallation costs are first tabulated on a present value basis at the
beginning of year 11, and then further discounted to the beginning of year 1. Both present values
are then summed and annualized over 20 years at a 7 percent discount rate.
31	Where year 1 would be the first year in which an office complies with the rule.
32	For the assessment of the rule's social costs, EPA used an additional discount rate of 3 percent and applied a
different discounting treatment (see Chapter 10.4).
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Table 10-5. Summary of Annualized Compliance Costs3 for Dental Office with No
Technology in Place (2016$)
Cost Element
Operating Size: Number of Chairs
1-2
3
4
5
6
7-14
15
Initial Installation Analysis
Total initial outlay
$695
$996
$996
$996
$1,357
$1,672
$3,389
Total annual (recurring) costs
$486
$597
$597
$597
$770
$943
$1,289
Present value total annual
(recurring)
$3,410
$4,190
$4,190
$4,190
$5,405
$6,620
$9,050
Total present value, at year 1
$4,105
$5,186
$5,186
$5,186
$6,762
$8,292
$12,439
Reinstallation Analysis — Equipment Reinstalled at Beginning of Year 11
Total initial outlay (0.5
installation charge)
$555
$835
$835
$835
$1,196
$1,470
$2,895
Total annual (recurring) costs
$486
$597
$597
$597
$770
$943
$1,289
Present value total annual
(recurring)
$3,410
$4,190
$4,190
$4,190
$5,405
$6,620
$9,050
Total present value, at year 11
$3,965
$5,025
$5,025
$5,025
$6,601
$8,090
$11,945
Total present value, at year 1
$2,016
$2,554
$2,554
$2,554
$3,356
$4,113
$6,072
Combining Initial Installation and Re-Installation
Sum, present values at year 1
$6,121
$7,740
$7,740
$7,740
$10,118
$12,405
$18,512
Total Annualized Cost
$578
$731
$731
$731
$955
$1,171
$1,747
Source: U.S. EPA, 2016a
a - Present values and annualized costs calculated using a 7 percent discount rate. All costs are on a pre-tax basis
and as of the time of compliance by complying entities.
Table 10-6. Summary of Annualized Compliance Costs3 for Dental Office with Technology
in Place (2016$)
Cost Element
Operating Size: Number of Chairs
1-2
3
4
5
6
7-14
15
Initial Installation Analysis
Total initial outlay
$23
$23
$23
$23
$23
$23
$23
Total annual (recurring) costs
$320
$375
$375
$375
$462
$548
$721
Present value total annual
(recurring)
$2,247
$2,637
$2,637
$2,637
$3,244
$3,852
$5,067
Total present value, at year 1
$2,270
$2,660
$2,660
$2,660
$3,267
$3,875
$5,090
Reinstallation Analysis — Equipment Reinstalled at Beginning of Year 11
Total initial outlay (0.5
installation charge)
$555
$835
$835
$835
$1,196
$1,470
$2,895
Total annual (recurring) costs
$320
$375
$375
$375
$462
$548
$721
Present value total annual
(recurring)
$2,247
$2,637
$2,637
$2,637
$3,244
$3,852
$5,067
Total present value, at year 11
$2,802
$3,472
$3,472
$3,472
$4,440
$5,322
$7,962
Total present value, at year 1
$1,424
$1,765
$1,765
$1,765
$2,257
$2,705
$4,047
Combining Initial Installation and Re-Installation
Sum, present values at year 1
$3,694
$4,425
$4,425
$4,425
$5,525
$6,580
$9,137
Total Annualized Cost
$349
$418
$418
$418
$521
$621
$863
Source: U.S. EPA, 2016a
a - Present values and annualized costs calculated using a 7 percent discount rate. All costs are on a pre-tax basis
and as of the time of compliance by complying entities.
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As discussed in Chapter 10.1.2, EPA anticipates that some dental offices that do not
already have an amalgam separator do not place or remove dental amalgam, and thus would
incur no treatment technology-related costs from the final dental category rule. Although these
offices will not incur treatment technology-related compliance costs, they will incur the cost of
the One-Time Compliance Report to document that they do not use amalgam in their operations.
EPA estimates this cost to be $23 for each of these offices.
In calculating the total compliance cost for the rule, these one-time reporting costs are
annualized using the discount rate and number of periods for non-recurring outlays, and added to
the total rule costs for offices incurring technology-related costs based on the estimated number
of offices not using dental amalgam.
10.2.2 Linking Compliance Costs By Number of Chairs to Dental Offices by Revenue
Range
The final step in developing compliance costs for use in the cost and economic impact
analysis is to link compliance costs by number of chairs to dental offices by revenue range. As
described in Chapter 10.1.1, the Economic Census reports information on dental offices by
revenue ranges. However, EPA determined that number of chairs is the key driver of technology
requirements, and thus estimated compliance requirements and costs based on the number of
chairs in the office. As a result, for estimating the compliance costs incurred by dental offices by
revenue range, it is essential to link offices by number of chairs to offices by revenue range. This
information is then used to estimate the total cost of regulatory compliance across dental
offices— based on numbers of offices by revenue range— and to estimate the impact of rule
requirements on dental offices, based on office revenue. Ideally, this linkage would have been
developed using a distribution of the number of chairs by dental office revenue range; however,
EPA was not able to obtain such data. As an alternative approach, EPA identified two sources of
data describing the distribution of number of chairs over all dental offices, regardless of office
revenue.
•	"An Economic Study of Expanded Duties of Dental Auxiliaries in Colorado" (ADA,
2009). This study is called the "ADA Colorado Study" below. Based on a survey of
154 dental offices in Colorado, it provides a distribution of number of chairs by
office.
•	"2009 Survey of Dental Practice: Income from the Private Practice of Dentistry"
(ADA, 2010). This study, called the "ADA National Study" below, indirectly reports
a distribution of number of chairs by office.
Table 10-7 summarizes the number-of-chair distributions from these sources. Although
these sources do not use the same number-of-chair ranges, the summary distributions are
relatively similar. For example, the ADA National Study's data distribution indicates that 56
percent of offices have four or fewer chairs and the ADA Colorado Study indicates 64 percent of
offices with four or fewer chairs.
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Chapter 10—Error! Reference source not found.
Table 10-7. Distribution of the Number of Chairs in Dental Offices
Number of Chairs in Office
Frequency
Relative Frequency
Running Total, Frequency
ADA Colorado Study, 2009
1-2
15
9.7%
9.7%
3
39
25.3%
35.1%
4
45
29.2%
64.3%
5
22
14.3%
78.6%
6
9
5.8%
84.4%
7 or more
24
15.6%
100.0%
ADA National Study, 2010
1-2
89
12.5%
12.5%
3-4
310
43.4%
55.9%
5-6
191
26.8%
82.6%
7 or more
124
17.4%
100.0%
Source: ADA, 2009; ADA, 2010
EPA used these distributions to estimate the number of chairs in offices that process
dental amalgam by revenue range. This estimation started with the assumption that increasing the
number of chairs in a dental office consistently increases office revenue.33 Beginning with the
lowest number-of-chairs range, one to two chairs, EPA assigned these offices to the lowest and
then successively higher revenue ranges until the entire percentage of offices with one or two
chairs was "used up." When the offices with a given number of chairs were "used up" without
exhausting a specific revenue range, the available percentage of offices with that number of
chairs was assigned within the revenue range assuming that offices are distributed uniformly by
revenue across the revenue range. Once the revenue "break point" was reached, offices from the
next higher number-of-chairs range were assigned to the remaining offices in the revenue range,
and successively higher revenue ranges until that part of the chairs distribution was "used up."
This process was repeated until all offices by "number of chairs" were assigned across all
revenue ranges.
Table 10-8 summarizes the assignment process and results for the ADA Colorado Study
and ADA National Study number-of-chair distributions. The table reports the assignment by
revenue range and number of chairs for all offices, regardless of baseline status, with the
exception of dental schools and military clinics. These establishments are not included in this
tally because EPA possesses no information on their revenue.
33 Exceptions to this assumption would include a dental office with exclusive clientele (i.e., an office with a small
number of chairs that is in a higher revenue range). EPA did not have data to evaluate these exclusive clientele
dental offices and therefore finds it reasonable to assume on a national basis that number of chairs in a dental office
increases with office revenue.
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Chapter 10—Error! Reference source not found.
Table 10-8. Number of Chairs in Dental Offices by Revenue Range
Revenue Range Values (2016$)
Offices By Revenue Range






(see Table 10-2)

(see Table 10-2)

With Allocation by Number of Chairs in Office



Percent of
Running
Number


Percent of
Running
Cumulative %>


Number of
Total
Total
of
Number
Running
Total
Total
from ADA
Low
High
Offices
Offices
Percent
Chairs
of Offices
Total
Offices
Percent
Distribution
Using ADA Colorado Study Distribution
$0
$10,491
63
0.05%
0.05%
1-2
63
63
0.05%
0.05%
9.74%
$10,492
$26,228
494
0.37%
0.42%
1-2
494
557
0.37%
0.42%

$26,229
$52,458
1,235
0.93%
1.35%
1-2
1,235
1,792
0.93%
1.35%

$52,459
$104,917
3,234
2.43%
3.77%
1-2
3,234
5,026
2.43%
3.77%

$104,918
$186,092
15,413
11.57%
15.34%
1-2
7,950
12,976
5.97%
9.74%

$186,093
$262,293
3
7,463
20,439
5.60%
15.34%
35.06%
$262,294
$483,513
31,153
23.38%
38.73%
3
26,275
46,714
19.72%
35.06%.

$483,514
$524,587
4
4,879
51,592
3.66%
38.73%
64.29%
$524,588
$913,751
45,899
34.45%
73.18%
4
34,050
85,642
25.56%
64.29%.

$913,752
$1,049,175
5
11,849
97,491
8.89%
73.18%
78.57%
$1,049,176
$1,415,091



5
7,183
104,674
5.39%
78.57%o

$1,415,092
$1,811,723
30,892
23.19%
96.37%
6
7,786
112,459
5.84%
84.42%o
84.42%
$1,811,724
$2,622,939



7-14
15,924
128,383
11.95%
96.37%
100.00%
$2,622,940
$5,245,879
4,291
3.22%
99.59%
7-14
4,291
132,674
3.22%
99.59%

$5,245,880
$10,491,759
474
0.36%
99.95%
7-14
474
133,148
0.36%
99.95%

$10,491,760
Or more
73
0.05%
100.00%
7-14
73
133,221
0.05%
100.00%)

Total3

133,221
100.00%

—
133,221

100.00%


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Chapter 10—Error! Reference source not found.
Table 10-8. Number of Chairs in Dental Offices by Revenue Range
Revenue Range Values (2016$)
Offices By Revenue Range






(see Table 10-2)

(see Table 10-2)

With Allocation by Number of Chairs in Office



Percent of
Running
Number


Percent of
Running
Cumulative %>


Number of
Total
Total
of
Number
Running
Total
Total
from ADA
Low
High
Offices
Offices
Percent
Chairs
of Offices
Total
Offices
Percent
Distribution
Using ADA National Study Distribution
0
$10,448
63
0.05%
0.05%
1-2
63
63
0.05%
0.05%
12.46%
$10,449
$26,120
494
0.37%
0.42%
1-2
494
557
0.37%
0.42%

$26,121
$52,242
1,235
0.93%
1.35%
1-2
1,235
1,792
0.93%
1.35%

$52,243
$104,485
3,234
2.43%
3.77%
1-2
3,234
5,026
2.43%
3.77%

$104,486
$231,731
15,413
11.57%
15.34%
1-2
11,580
16,606
8.69%
12.46%

$231,732
$261,213
3-4
3,833
20,439
2.88%
15.34%
55.88%
$261,214
$522,427
31,153
23.38%
38.73%
3-4
31,153
51,592
23.38%
38.73%

$522,428
$760,147
45,899
34.45%
73.18%
3-4
22,855
74,447
17.16%
55.88%.

$760,148
$1,044,856
5-6
23,044
97,491
17.30%
73.18%
82.63%
$1,044,857
$1,539,698
30,892
23.19%
96.37%
5-6
12,594
110,085
9.45%
82.63%.

$1,539,699
$2,612,141
7+
18,298
128,383
13.74%
96.37%
100.00%
$2,612,142
$5,224,283
4,291
3.22%
99.59%
7+
4,291
132,674
3.22%
99.59%

$5,224,284
$10,448,567
474
0.36%
99.95%
7+
474
133,148
0.36%
99.95%

$10,448,568
Or more
73
0.05%
100.00%
7+
73
133,221
0.05%
100.00%)

Total3

133,221
100.00%

—
133,221

100.00%


Source: ADA, 2009, ADA, 2010, U.S. EPA, 2016a
a - The total 133,221 offices include the entire dental industry as reported in U.S. Census Bureau, 2012b, including those dental specialists discussed in Chapter
10.1.2 that are not subject to the rule.
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Chapter 10—Economic Impacts for the Dental Industry
10.2.3 Estimated Cost of Compliance to Dental Offices
To estimate the total nationwide cost of compliance to dental offices of the rule, EPA
multiplied the estimated total annualized cost of rule compliance by the number of chairs for
dental offices (see Chapter 10.1.2). EPA then added these values over the size ranges to yield the
total estimated compliance cost. These calculations account for baseline compliance status (i.e.,
whether offices are assumed to have already installed amalgam separators). These costs are the
pre-tax costs estimated to be incurred by complying offices as of the year of compliance.
EPA completed these calculations separately for the two distributions of offices by
number of chairs. Table 10-9 summarizes the results from these calculations. These total
compliance cost estimates include the one-time reporting costs those dental offices that do not
process dental amalgam, as described in Chapter 10.2.1.
Table 10-9. Annualized Costs to Complying Dental Offices by Number of Chairs
Annualized Cost (Millions, 2016$) for Alternative Number-of-Chairs Distributions3
Number of Chairs
Colorado Survey
ADA Survey
1-2 chairs
$4.7
$6.0
3 chairs
$15.2
$26.1
4 chairs
$17.5
5 chairs
$8.6
$18.4
6 chairs
$4.5
7-14 chairs
$14.6
$16.3
15 chairs
$0.4
$0.4
Total Costs
$65.5
$67.1
Source: U.S. EPA, 2016a
a - Present values and annualized costs are calculated using a 7 percent discount rate. All costs are on a pre-tax
basis and as of the time of compliance by complying entities.
Costs are higher for the ADA National Study data distribution compared to the ADA
Colorado Study data distribution because the ADA National Study data distribution indicates
more higher-number-of-chair offices than does the ADA Colorado Study data distribution. For
example, 44 percent of offices are estimated to have five or more chairs under the ADA National
Study data distribution compared to 36 percent of offices under the ADA Colorado Study data
distribution. Both estimates cover the same number of offices.
10.3 Economic Impact Of Compliance Costs
EPA devised a set of tests for analyzing economic achievability. As is often the practice,
EPA conducted a cost-to-revenue analysis to examine the relationship between the costs of the
final rule to current (or pre-rule) dental office revenues (Chapter 10.3.1). In addition, EPA chose
to examine the financial impacts of the rule using two measures that utilize the data EPA has on
dental office baseline assets and estimated replacement capital costs: (1) ratio of the rule's capital
costs to total dental office capital assets (Chapter 10.3.2); and (2) ratio of the rule's capital costs
to annual dental office capital replacement costs (Chapter 10.3.3).
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Chapter 10—Economic Impacts for the Dental Industry
10.3.1 Cost-to-Revenue Analysis
The cost-to-revenue measure compares the annualized cost of regulatory compliance, at a
7 percent discount rate, with the revenue of regulated dental offices, and provides a screening-
level assessment of the impact of compliance costs on dental offices. The cost-to-revenue
measure assesses the loss in operating profit, on a constant annual cost basis, as a percentage of
baseline revenue that a business would incur if none of the compliance costs were passed
forward to customers. In using this impact measure, EPA assesses whether the compliance cost
exceeds thresholds of one and three percent of revenue. This impact measure is also used in the
Regulatory Flexibility Act assessment, described in Chapter 10.5 below.
EPA framed the cost-to-revenue analysis around the revenue range/number-of-chairs
combinations, as developed in Table 10-8, and the total annualized compliance costs that would
occur within each of these analysis combinations. Table 10-10 summarizes these analytic
combinations. Note that EPA was not able to perform the cost-to-revenue impact analysis for
dental schools and military clinics, as it has no revenue information for them. However, since
EPA performed the cost-to-revenue analysis on a range of office sizes, EPA projects the results
of this analysis would be similar for these entities.
In general, EPA assessed that cost impact analyses should be performed using after-tax
costs, as these costs account for the reduction in costs to affected entities resulting from tax
deductibility of the outlays, and thus provide a better indication of the financial impact of
regulatory requirements on complying entities. In the cost-to-revenue analysis for the final dental
category rule, EPA used costs on a pre-tax instead of after-tax basis, because the appropriate tax
rates for complying entities, which are often sole proprietorships or partnerships, are not known.
Using pre-tax instead of after-tax costs increases the likelihood of finding that costs exceed the
one percent or three percent of revenue impact threshold.
Table 10-10. Revenue Range/Number-of-Chairs Combinations for Cost Impact Analysis
Revenue Ran
ge/Number of Chairs Combinations
Number of
Offices Incurring
Costs
Percent of Cost-
Incurring Offices
Low
High
Number of Chairs
Using ADA Colorado Study Distribution
$0
$10,491
1-2
55
0.0%
$10,492
$26,228
1-2
432
0.4%
$26,229
$52,458
1-2
1,078
0.9%
$52,459
$104,917
1-2
2,824
2.4%
$104,918
$186,092
1-2
6,941
6.0%
$186,093
$262,293
3
6,516
5.6%
$262,294
$483,513
3
22,940
19.7%
$483,514
$524,587
4
4,259
3.7%
$524,588
$913,751
4
29,728
25.6%
$913,752
$1,049,175
5
10,345
8.9%
$1,049,176
$1,415,091
5
6,271
5.4%
$1,415,092
$1,811,723
6
6,798
5.8%
$1,811,724
$2,622,939
7-14
13,903
12.0%
$2,622,940
$5,245,879
7-14
3,746
3.2%
$5,245,880
$7,500,000
7-14
178
0.2%
$7,500,001
$10,491,759
7-14
236
0.2%
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Chapter 10—Economic Impacts for the Dental Industry
Table 10-10. Revenue Range/Number-of-Chairs Combinations for Cost Impact Analysis
Revenue Ran
ge/Number of Chairs Combinations
Number of
Offices Incurring
Costs
Percent of Cost-
Incurring Offices
Low
High
Number of Chairs
$10,491,760
Or more
7-14
64
0.1%
Total
116,313
100.0%
Using ADA National Study Distribution
$0
$10,491
1-2
55
0.0%
$10,492
$26,228
1-2
432
0.4%
$26,229
$52,458
1-2
1,078
0.9%
$52,459
$104,917
1-2
2,824
2.4%
$104,918
$223,156
1-2
10,110
8.7%
$223,157
$262,293
3-4
3,347
2.9%
$262,294
$524,587
3-4
27,200
23.4%
$524,588
$785,800
3-4
19,954
17.2%
$785,801
$1,049,175
5-6
20,119
17.3%
$1,049,176
$1,690,745
5-6
10,995
9.5%
$1,690,746
$2,622,939
7-14
15,976
13.7%
$2,622,940
$5,245,879
7-14
3,746
3.2%
$5,245,880
$7,500,000
7-14
178
0.2%
$7,500,001
$10,491,759
7-14
236
0.2%
$10,491,760
Or more
7-14
64
0.1%
Total
116,313
100.00%
Source: U.S. EPA, 2016a
Costs of compliance were assigned to each revenue range/number-of-chairs combination
and then assessed relative to the low and high revenue values of a revenue range to determine
whether offices within the revenue range would incur costs exceeding a given percent of revenue
threshold. For each revenue range/number-of-chairs combination and a given percent of revenue
threshold — i.e., one or three percent — EPA evaluated three cases:
1.	If the calculated cost-to-revenue percentage is less than the threshold value at the low
end of the revenue range, then EPA assessed that none of the dental offices in that
revenue range would incur costs exceeding the given percent of revenue threshold.
2.	If the calculated cost-to-revenue percentage exceeds the threshold value at the high
end of the revenue range, then EPA assessed that all of the dental offices in that
revenue range would incur costs exceeding the given percent of revenue threshold.
3.	If neither of the two prior conditions are met, this indicates that some, but not all, of
the offices in the revenue range would exceed the percent of revenue threshold. To
determine the number of offices exceeding the given percent of revenue threshold,
EPA calculated the "break-even" revenue value for a given compliance cost and
percent of revenue threshold, by dividing the compliance cost value by the given
percent of revenue threshold. This break-even value is the revenue value at which
compliance cost equals the percent of revenue threshold; offices with revenue below
the break-even value will incur costs exceeding the given percent of revenue
threshold, while offices with revenue above it will incur costs below the percent of
revenue threshold. To calculate the number of offices with costs exceeding the
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Chapter 10—Economic Impacts for the Dental Industry
percent of revenue threshold, EPA assumed that offices are distributed uniformly
within the revenue range and calculated the fraction of offices below the break-even
value as follows:
Fraction exceeding threshold = (RVbe — RVmin) -h (RVmax — RVmiri)
Where:
RVbe
RVmin
RVmax
Break-even revenue
Minimum value in revenue range
Maximum value in revenue range
EPA tallied the estimated fraction of offices within each number-of-chairs/revenue range
combination that exceed a given percent of revenue threshold. Results were developed separately
for both the ADA Colorado Study and ADA National Study chairs-by-office distributions and
accounting for technology-in-place status.
Because EPA does not have detailed data on baseline financial conditions of dental
offices, the effect of the pretreatment standard on dental office income statements and balance
sheets cannot be measured by a closure analysis (as is EPA's more typical practice for analyzing
economic achievability). Closure analyses typically rely on accounting measures such as present
value of after-tax cash flow. However, such accounting measures are difficult to implement for
businesses that are organized as sole proprietorships or partnerships. Still, the 2012 Economic
Census reports that approximately 557 offices of the approximately 133,221 total offices had
revenue of less than $25,000 (2012 dollar basis; see Table 10-1). In reviewing the implied
operating characteristics of these low-revenue offices, EPA considered whether these offices
should be excluded from the analyses on any of the following bases:
•	A low-revenue office could be a single-dentist and/or part-time business that provides
services as a subcontractor on an independent fee-for-service basis, such as dental
hygiene, in a general service dental office that is owned and operated by a larger
dental practice. Because these establishments would not be the primary
owner/operator of the dental offices in which they provide services, they would not
directly incur the compliance costs of the final Dental Amalgam Rule. If they
incurred any of these costs, it would be on a limited fractional share basis, most likely
in proportion to the total value of their services as a fraction of the total revenue in the
office. Alternatively, if these operators offer their services in a competitive market, it
may be that none of the compliance costs are shared by these subcontractors.
•	Another possibility is that some of these very low-revenue offices could be non-profit
groups that provide pay-as-you-can or free services to low-income populations. In
this case, these small businesses may be viable enterprises because they receive in-
kind donations not counted as revenue (e.g., services of a practicing dentist).
•	Alternatively, these very low revenue establishments could be non-viable as for-profit
businesses, if they are attempting to operate as general service dental practices. This
reasoning is based on EPA's assessment of the ongoing outlay required for
replacement of existing dental office capital equipment, which was performed for the
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Chapter 10—Economic Impacts for the Dental Industry
third part of the cost impact analysis (Chapter 10.3.3, below). Specifically, in this
analysis, EPA estimated that one- to two-chair offices would incur capital
replacement costs of approximately $25,400 per year (the estimated annual cost of
keeping equipment in good working order; 2016 dollar basis). This outlay would
exceed the annual revenue of the business in the below-$25,000 revenue range.
Accordingly, these offices may not be operating viably as general service dental
offices.
Given these considerations, EPA performed the cost-to-revenue analysis on two bases:
•	Excluding the low-revenue offices (below $25,400 revenue) from the cost-to-revenue
analysis.
•	Including the low-revenue offices in the cost-to-revenue analysis.
For the rest of the economic analysis chapter, EPA refers to the low-revenue offices as
"baseline set-aside offices."
Following the methodology outlined above, EPA estimated the occurrence of cost-to-
revenue exceeding the one and three percent of revenue thresholds for the final rule for the ADA
Colorado Study and ADA National Study chairs-by-office distributions. As described above,
EPA accounted for the number of offices estimated to have already installed amalgam separator
technology, and the resulting compliance cost for these cases, in the cost-to-revenue calculations.
For offices that certify that they do not place or remove amalgam - and have a one-time
certification cost only - EPA assumed that costs would be less than 1 percent of revenue.
Table 10-11 and Table 10-12 summarize the results from this analysis. Table 10-11
reports the results by technology-in-place status; Table 10-12 reports the results by number-of-
chair ranges. These findings are the same for both the ADA National Study and ADA Colorado
Study chairs-by-office distributions.
With the baseline set-aside offices excluded from the analysis, EPA estimates that 808
dental offices would incur costs exceeding one percent of revenue, representing 0.7 percent of
dental offices expected to incur costs under the final regulation. No offices incur costs exceeding
three percent of revenue. With the baseline set-aside offices included in the analysis, EPA
estimates that 1,217 dental offices would incur costs exceeding one percent of revenue,
representing 1.0 percent of dental offices expected to incur costs under the final rule; 174 offices
are estimated to incur costs exceeding three percent of revenue, representing 0.1 percent of
offices expected to incur costs under the final rule.
Of note, all of the instances in which the cost-to-revenue impact value exceeds one or
three percent occur among dental offices in revenue ranges below the small business revenue
threshold of $7.5 million. This finding is relevant for Chapter 10.5.
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Chapter 10—Economic Impacts for the Dental Industry
Table 10-11. Cost-to-Revenue Analysis Impact Summary3
Offices with Cost Exceeding 1 Percent of Revenue
Offices with Cost Exceeding 3 Percent of Revenue
Technology
No-Tech-
Total
Percentageb
Technology
No-Tech-
Total
Percentage2
-In-Place
in-Place


-In-Place
in-Place


Excluding Baseline Set-Aside Offices from Analysis
156
652
808
0.7%
0
0
0
0.0%
Including Baseline Set-Aside Offices in Analysis
347
871
1,217
1.0%
35
139
174
0.1%
Source: U.S. EPA, 2016a
a - Number of offices with costs exceeding 1 percent and 3 percent of revenue includes those offices with some
teclinology-related costs, and excludes a) offices not subject to the rule, and b) dental schools and military
clinics for which EPA does not have revenues. EPA assumes that offices with reporting costs only (those that
certify that they do not place or remove amalgam) will have costs less than 1% of revenues,
b - Percentages of affected offices are calculated as a fraction of total offices estimated to incur any costs under
the dental category rule for which revenue data are available (116,313 offices).
Table 10-12. Cost-to-Revenue Analysis Impact Summary by Number of Chairs3
Number of
Excluding Baseline Set-Aside Offices from
Including Baseline Set-Aside Offices in
Chairs

Analysis


Analysis


Costs >1% Rev.
Costs >3% Rev.
Costs >1% Rev.
Costs >3% Rev.

Number
%
Number
%
Number
%
Number
%
1-2 chairs
808
6.3%
0
0.0%
1,217
9.4%
174
1.4%
3 chairs
0
0.0%
0
0.0%
0
0.0%
0
0.0%
4 chairs
0
0.0%
0
0.0%
0
0.0%
0
0.0%
5 chairs
0
0.0%
0
0.0%
0
0.0%
0
0.0%
6 chairs
0
0.0%
0
0.0%
0
0.0%
0
0.0%
7-14 chairs
0
0.0%
0
0.0%
0
0.0%
0
0.0%
Total
808
0.7%
0
0.0%
1,217
1.0%
174
0.1%
Source: U.S. EPA, 2016a
a - Percentages of affected offices are calculated as a fraction of total offices estimated to incur any costs under
the dental category rule for which revenue data are available (116,313 offices). EPA assumes that offices with
reporting costs only (those that certify that they do not place or remove amalgam) will have costs less than 1% of
revenues.
From this analysis, due to the small percentage of offices potentially incurring costs over
one percent or three percent of revenue, EPA finds that the final rule would not have a material
adverse impact on the dental office sector.
10.3.2 Ratio of the Final Rule's Capital Costs to Total Dental Office Capital Assets
From the preceding analysis, EPA found that the final rule will have minimal impact on
operating finances given that less than one percent of dental offices may incur annualized
compliance costs exceeding one or three percent of revenue. Given this finding, it is possible that
the more material impact of the final dental category rule could result from the need of dental
offices to finance the initial outlays required for rule compliance — in particular, technology
purchase and installation. Accordingly, EPA undertook two additional analyses of potential
impact based on the requirement to finance the initial outlay. The first of these, presented in this
chapter, examines the initial outlay in relation to the baseline value of assets on the balance sheet
of dental office businesses. The second analysis, presented in Chapter 10.3.3, examines the initial
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Chapter 10—Economic Impacts for the Dental Industry
outlay in relation to the estimated steady state outlays for capital replacement for the dental
office business. The steady state capital replacement outlay represents a value dental offices may
reasonably expect to spend in the periodic outlays to replace and/or upgrade dental office capital
equipment. For both tests, EPA assumed that a low ratio implies limited impact on dental
offices' ability to finance the initial spending on compliance capital costs of the final rule. A high
ratio may still allow costs to be financed but could imply a need to change capital planning and
budgeting.
For the analysis of capital outlays in relation to baseline assets, EPA relied on data from
Risk Management Association (RMA)34 to estimate the baseline assets of dental offices by
revenue range. Specifically, EPA used asset to sales ratios for the dental office sector to estimate
an asset value for the minimum and maximum revenue values for each of the revenue
range/number of chairs combinations as analyzed in the preceding chapter. Each revenue
range/number of chairs combination then has a minimum and maximum asset value for use in
the capital outlay to baseline asset value analysis. The RMA data have the limitation that they
may not be fully representative of all dental offices, because they only represent dental offices
that are successful borrowers. Hence, the RMA data may underrepresent offices that are not
financially healthy. This would cause EPA's finding of impact to understate the actual impacts.
Using the same approach to assigning compliance requirements to the revenue
range/number-of-chairs analysis combinations, as described in Chapter 10.3.1, EPA then
assigned the initial outlays only to the revenue range/number-of-chairs analysis combinations.
The values of initial outlays were then compared to the minimum and maximum values of each
revenue range/number-of-chairs analysis combination to assess the potential capital
outlay/financing burden. In the same way as described for the preceding cost-to-revenue
analysis, the capital outlay to baseline asset value analysis accounted for whether offices have
already installed amalgam separator technology and also used the alternative number of chairs by
office distributions (ADA Colorado Study and ADA National Study). Also, EPA performed this
analysis both including and excluding the baseline set-aside offices. For the analysis including
the baseline set-aside offices, EPA assumed a minimum revenue value of $5,000 (and the
corresponding baseline assets value) for the lowest revenue range, to prevent division by zero.
Table 10-13 reports the findings from this analysis, specifically the average outlay-to-
assets ratio values by operating size (number of chairs), and the weighted average of the outlay-
to-assets ratio across the number-of-chairs ranges. As with the cost-to-revenue impact analysis,
EPA did not perform this analysis for dental schools and military clinics, as it has no financial
data on which to base the analysis. However, since EPA performed this analysis on a range of
office sizes, EPA projects that the results of this analysis would be similar for these entities.
34 RMA reports financial statement information received from lending institutions, for businesses in a wide range of
economic sectors, including dental offices. These data include a wide range of income statement and balance sheet
information as well as financial and operating ratios.
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Chapter 10—Economic Impacts for the Dental Industry
Table 10-13. Initial Compliance Outlay as a Percentage of Baseline Assets
Number of Chairs
Technology-in-Place
No Technology-in-Place
Low
High
Low
High
Excluding Baseline Set-Aside Offices from Analysis
1-2 chairs
0.1%
0.0%
2.4%
1.2%
3 chairs
0.0%
0.0%
0.9%
0.5%
4 chairs
0.0%
0.0%
0.6%
0.4%
5 chairs
0.0%
0.0%
0.3%
0.2%
6 chairs
0.0%
0.0%
0.3%
0.2%
7-14 chairs
0.0%
0.0%
0.2%
0.1%
Total
0.0%
0.0%
0.7%
0.4%
Including Baseline Set-Aside Offices in Analysis
1-2 chairs
0.1%
0.0%
3.0%
1.5%
3 chairs
0.0%
0.0%
0.9%
0.5%
4 chairs
0.0%
0.0%
0.6%
0.4%
5 chairs
0.0%
0.0%
0.3%
0.2%
6 chairs
0.0%
0.0%
0.3%
0.2%
7-14 chairs
0.0%
0.0%
0.2%
0.1%
Total
0.0%
0.0%
0.7%
0.4%
Source: U.S. EPA, 2016a
In both baseline set-aside scenarios (excluding or including these offices in the analysis),
the initial capital costs to total capital assets values are low, with an average value of 0.4 percent
to 0.7 percent for no-technology-in-place offices and 0 percent for the technology-in-place
offices. EPA finds these results to indicate that dental offices should not encounter difficulty in
financing the increase in assets that would result from installing amalgam separators.
10.3.3 Ratio of the Final Rule's Capital Costs to Annual Dental Office Capital
Replacement Costs
As another test of the potential burden of financing the initial outlays for rule compliance,
EPA compared the initial outlay with estimated steady state outlays for capital replacement for
the dental office business. As stated above, the steady state capital replacement outlay represents
a value dental offices may reasonably expect to spend in the periodic outlays to replace and/or
upgrade dental office capital equipment. EPA assumed a low ratio implies limited impact on
dental offices' ability to finance the initial spending on capital costs of the final rule. A high ratio
may still allow costs to be financed but could imply a need to change capital planning and
budgeting.
For this comparison, EPA relied on data describing the equipment needs and costs for
starting a dental practice as compiled in Safety Net Dental Clinic Manual, prepared by the
National Maternal and Child Oral Health Resource Center at Georgetown University
(Georgetown University, 2003). This publication reports overall costs in broad categories of
major and small items for two specific number-of-chair offices (three chairs and six chairs) and
provides additional detail on specific equipment needs for the six-chair office, including the
estimated service life for the various items of equipment. EPA worked with these data in several
ways to develop an estimate of the steady state capital replacement outlay:
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Chapter 10—Economic Impacts for the Dental Industry
•	EPA used the detailed cost and service life information for the six-chair office to
develop a profile of startup outlays by service life and developed percentages of total
startup outlay by service life for two broad categories of major and small items (see
Table 10-14).
•	EPA used the aggregate cost information by the major and small item categories, for
the three- and six-chair offices, to estimate startup outlays for other number-of-chair
offices to be accounted for in the analysis. EPA interpolated between and/or
extrapolated from the three- and six-chair office values to develop the startup cost
estimates for the other chair size offices, including additional analysis for the eight-
and nine-chair offices. EPA adjusted some of the values for the one- or two-chair
office to reflect the fact that some equipment needs have a minimum number and/or
cost regardless of how few chairs are in the office. The first chapter of Table 10-15,
"Initial Outlays" by major and small items, reports the results from this step (EPA
assumed initial compliance outlay for eight- and nine-chair offices is the same as a
seven-chair office).
•	EPA allocated the broad components of cost — major and small items — for each
office size, into the specific service life categories based on the service life
percentages reported in Table 10-14. The second chapter of Table 10-15, "Initial
Outlays by Equipment Life Category," reports the results from this step.
•	To estimate a steady-state replacement outlay, EPA divided the estimated outlays for
each service life category by the number of years for the service life category, and
summed these values over the service life categories for each of the number-of-chair
office specifications. EPA recognizes that outlays for capital replacement and/or
refurbishment will not generally occur on a uniform basis from year to year, but on
average, over a period of several years, the annual replacement and/or refurbishment
outlay should be approximately this "steady state" value. The third chapter of Table
10-15, "Steady State Annual Replacement Outlay, by Equipment Life Category,"
reports the results from this step.
Table 10-14. Cost of Dental Equipment for Six-Chair Office by Equipment Life
Useful Life Category
Value by Service Life Category (2016$)a
Major Items
Percent
Small Items
Percent
3
$0
0.0%
$25,200
21.5%
5
$66,562
21.5%
$0
0.0%
10
$100,702
32.6%
$91,811
78.5%
12
$8,718
2.8%
$0
0.0%
15
$133,055
43.1%
$0
0.0%
Total
$309,037
100.0%
$117,011
100.0%
Source: U.S. EPA, 2016a; based on 6-chair office specifications from Georgetown University, 2003.
a - All costs updated to 2016$ using the Implicit Price Deflators for Gross Domestic Product (U.S. BLS, 2016).
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Chapter 10—Economic Impacts for the Dental Industry
Table 10-15. Initial and Annual Replacement Outlay for
Startup Dental Office by Number of Chairs (2016$)a

Number of Chairs
1-2
3
4
5
6
7
8
9
Initial Outlays
Major items
$178,611
$235,748
$279,003
$322,257
$365,512
$408,766
$452,021
$471,537
Small items
$42,185
$66,458
$86,792
$107,126
$127,460
$147,794
$168,128
$187,698
Total
$220,796
$302,206
$365,795
$429,383
$492,972
$556,560
$620,149
$659,235
Initial Outlays by Equipment Life Category
3
$9,085
$14,313
$18,692
$23,071
$27,450
$31,830
$36,209
$40,424
5
$38,470
$50,777
$60,093
$69,409
$78,726
$88,042
$97,359
$101,562
10
$91,302
$128,966
$159,015
$189,065
$219,114
$249,164
$279,214
$300,929
12
$5,039
$6,651
$7,871
$9,091
$10,311
$11,531
$12,752
$13,302
15
$76,901
$101,501
$120,124
$138,747
$157,370
$175,993
$194,616
$203,019
Total
$220,796
$302,206
$365,795
$429,383
$492,972
$556,560
$620,149
$659,235
Steady State Annual Replacement Outlay, by Equipment Life Category
3
$3,028
$4,771
$6,231
$7,690
$9,150
$10,610
$12,070
$13,475
5
$7,694
$10,155
$12,019
$13,882
$15,745
$17,608
$19,472
$20,312
10
$9,130
$12,897
$15,902
$18,906
$21,911
$24,916
$27,921
$30,093
12
$420
$554
$656
$758
$859
$961
$1,063
$1,109
15
$5,127
$6,767
$8,008
$9,250
$10,491
$11,733
$12,974
$13,535
Total
$25,399
$35,144
$42,815
$50,486
$58,157
$65,829
$73,500
$78,523
Source: U.S. EPA, 2016a
a - All costs updated to 2016$ using the Implicit Price Deflator for Gross Domestic Product (U.S. BLS, 2016).
As the final step in this analysis, EPA compared the estimated total initial outlay for the
final dental category rule to the estimated steady state annual replacement outlay values, from
Table 10-15. Table 10-16 reports the results from this comparison. As shown in Table 10-16, the
values for initial compliance outlay as a percentage of replacement outlay are quite low, ranging
from 2.0 percent to 2.8 percent, with a weighted average of 2.4 percent across all number-of-
chair ranges.
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Chapter 10—Economic Impacts for the Dental Industry
Table 10-16. Comparing Total Initial Compliance Outlay to Steady State Annual Replacement Outlay by Number of Chairs
(Chapter 10.3.3; 2016$)

Number of Chairs

1-2
3
4
5
6
7
8
9
Weighted
Average
Initial compliance outlay
$695
$996
$996
$996
$1,357
$1,672
$1,672
$1,672
$1,109
Baseline annual replacement outlay
$25,399
$35,144
$42,815
$50,486
$58,157
$65,829
$73,500
$78,523
$46,523
Initial compliance outlay as
percentage of replacement outlay
2.7%
2.8%
2.3%
2.0%
2.3%
2.5%
2.3%
2.1%
2.4%
Source: U.S. EPA, 2016a
Table 10-17. Comparing Total Initial Compliance Outlay to Initial Outlay by Number of Chairs (Chapter 10.3.4; 2016$)

Number of Chairs

1-2
3
4
5
6
7
8
9
Weighted
Average
Initial compliance outlay
$695
$996
$996
$996
$1,357
$1,672
$1,672
$1,672
$1,109
Initial outlay
$220,796
$302,206
$365,795
$429,383
$492,972
$556,560
$620,149
$659,235
$396,319
Initial compliance outlay as
percentage of office startup costs
0.3%
0.3%
0.3%
0.2%
0.3%
0.3%
0.3%
0.3%
0.3%
Source: U.S. EPA, 2016a
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Chapter 10—Economic Impacts for the Dental Industry
10.3.4 Economic Impact for New Sources
EPA assessed whether the pretreatment standard for new sources would impose a barrier
to entry. To perform this analysis, EPA relied on data describing the equipment needs and costs
for starting a dental office as compiled in the Safety Net Dental Clinic Manual, prepared by the
National Maternal and Child Oral Health Resource Center at Georgetown University. EPA
calculated the initial outlay to start a dental office as shown above in Table 10-15. EPA then
compared the initial compliance cost for dental offices as estimated in Chapter 10.2 to these
startup values. This comparison demonstrates that the amalgam separator capital costs would
represent only 0.2 percent to 0.3 percent of the cost of starting a dental office and, therefore, do
not pose a barrier to entry (see Table 10-17 above).
10.4 Social Cost Of The Final Dental Category Rule
The previous chapters reviewed the estimated costs of the final dental category rule to
dental offices and assessed the potential impact of the final rule on these offices. This chapter
reviews the costs of the final dental category rule from the standpoint of cost to society, or social
cost. The assessment of social cost builds from the estimated costs of regulatory compliance, as
described in Chapter 10.2.1, but differs from the assessment of costs to dental offices in the
following respects:
•	The assessment of cost of compliance to dental offices used a discount rate of 7
percent for developing present and annualized values. As described previously, the 7
percent discount rate represents an estimated opportunity cost of capital to society, on
a pre-tax, constant dollar basis. The analysis of social cost uses an additional discount
rate, 3 percent, which represents a societal rate of time preference — the rate at which
society desires to be compensated for deferring consumption from one year to the
next. Social costs are presented on the basis of both 3 and 7 percent discount rates.
•	The assessment of cost of compliance to dental offices included only the costs
incurred by these offices. The assessment of social cost includes these costs of
compliance, but also includes an additional cost that will be incurred by society,
namely the cost to permitting authorities for administering the final dental category
rule.
•	The assessment of cost of compliance to dental offices developed present values and
annualized costs as of the time at which dental offices would comply with the rule's
requirements, regardless of the specific calendar year in which compliance would
occur. The assessment of social cost develops present and annualized values as of the
expected year of rule promulgation, 2016, and the compliance period three years
following promulgation, in 2019. Specifically, using the analytic convention outlined
previously for the assessment of compliance costs to dental offices, costs are first
developed over an assumed 20-year compliance period, which reflects initial
installation of compliance equipment at the first year of compliance, and then
reinstallation at the 11th year of the 20-year analysis period. These costs are
discounted to the year of compliance and then annualized over the 20 years of rule
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Chapter 10—Economic Impacts for the Dental Industry
compliance. These present and annualized values, which are assumed to be as of
2019, or the first year of required compliance, are then discounted an additional three
years to 2016, the year of rule promulgation.
In assessing social costs, EPA assumed that the regulation would result in no change in
the total quantity of services provided by the dental industry. Thus, the social cost analysis
includes no loss in economic surplus to society due to contraction of dental industry output, and
the social cost estimate includes only the resource costs of compliance and rule administration.
Given that the rule's total annualized costs are estimated to represent less than 0.1 percent of the
total value of dental services,35 EPA assesses that the assumption of no change in industry output
is reasonable.
10.4.1 Cost of Compliance on Social Cost Basis
For the analysis of social cost, compliance costs are developed on the same basis as
described in Chapter 10.2, with the exceptions, as noted above, that costs are calculated on a
present value and annualized cost basis as of the year of rule promulgation, 2016, and using 3
percent and 7 percent discount rates. Table 10-18 summarizes these cost values for the final rule
by the alternative number-of-chair distributions.
Table 10-18. Compliance Costs on a Social Cost Basis for Final Dental Amalgam Rule
Annualized Cost (Millions, $2016) as of 2016, Year of Rule Promulgation

Using 3 Percent Discount Rate
Using 7 Percent Discount Rate
Colorado Survey
ADA Survey
Colorado Survey
ADA Survey
Compliance cost
$58.6
$60.0
$53.5
$54.8
Source: U.S. EPA, 2016a
10.4.2 Administrative Costs
As described above, these costs are calculated for the year of rule promulgation, 2016, as
$814,000 at a 7 percent discount rate and $785,000 at a 3 percent discount rate. As discussed in
Chapter 1.2.2, the Control Authority could be the publicly owned treatment works (POTW), the
state, or U.S. EPA Region. EPA estimated the annual recordkeeping costs for the following
Control Authorities:
•	403.10(e) States: 5 Control Authorities;
•	POTWs: 1,600 Control Authorities;36
•	Approved Pretreatment States (minus the 403.10(e) States): 31 Control Authorities;
and
35	Approximately $110 billion based on 2012 Economic Census data (U.S. Census Bureau, 2012a) and updated to
2016 dollars using Implicit Price Deflators for Gross Domestic Product (U.S. BLS, 2016).
36	Estimated approved Control Authority POTWs nationwide via U.S. EPA, 2011.
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Chapter 10—Economic Impacts for the Dental Industry
• U.S. EPA Regions: 9 Control Authorities.37
EPA used a labor rate estimate of $58.56/hour38 for these Control Authorities and an
appropriate time estimate for each activity mentioned above (e.g., recordkeeping) (U.S. EPA,
2016d). Annual costs were assumed to meet a five-year compliance schedule. Administrative
costs were assumed over a three-year period, because of the pretreatment standards program
information collection request (ICR) that is completed every three years (U.S. EPA, 2011).
10.4.3 Total Social Cost
Table 10-19 summarizes the estimated total social cost for the final dental category rule,
including both compliance costs and administrative costs. Costs are reported for the 3 percent
and 7 percent discount rates.
Table 10-19. Summary of Social Cost for Final Dental Category Rule
Annualized Cost (Millions, $2016) as of Year of Rule Promulgation
Cost Category
Using 3 Percent Discount Rate
Using 7 Percent Discount Rate
Colorado Survey
ADA Survey
Colorado Survey
ADA Survey
Compliance cost
$58.6
$60.0
$53.5
$54.8
Cost to permitting authorities
$0.8
$0.8
$0.8
$0.8
Total social cost
$59.4
$60.8
$54.3
$55.6
Source: U.S. EPA, 2016a
10.5 Regulatory Flexibility Act Assessment
As part of the cost and economic impact assessment for the final dental category rule,
EPA considered the potential impact on small entities in the dental office business. Of key
concern in this assessment is whether the final dental category rule could cause a significant
impact on a substantial number of small entities (SISNOSE).
As reported previously, the Small Business Administration criterion for defining a small
entity in the dental office sector (NAICS 621210) is $7.5 million in revenue. In the same way as
for the previous general economic impact analysis, EPA framed its small entity analysis around
establishments, or individual dental offices, instead of using the firm. Because nearly 98 percent
of dental office firms are single unit businesses (U.S. Census Bureau, 2012b), there is minimal
difference in performing this analysis at the level of the dental office compared to the dental
firm.
To estimate the number of number of small business dental offices, EPA relied on dental
office counts from the Economic Census, as used elsewhere in this analysis. EPA first segmented
the Economic Census revenue range that contains the small business criterion into office counts
that are above and below the criterion, assuming that offices are uniformly distributed across this
revenue range according to revenue size. This segmentation applies to less than one percent of
37	All states in Region 4 have approved pretreatment programs, so the state lias the approval authority.
38	Based on the Metal Products and Machinery 150 POTW Study (1999$: U.S. EPA, 2000). EPA updated to 2016$
using the Bureau of Labor Statistics Cost Index for State and Local Government Public Administration.
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Chapter 10—Economic Impacts for the Dental Industry
the total number of small businesses in the dental office sector, so the error introduced by
assuming a uniform distribution is minor, at most, in the overall analysis.
In addition, as described previously, EPA also estimated that some dental offices subject
to the rule do not process dental amalgam, and thus will incur only one-time reporting costs
pursuant to the dental category rule.
EPA estimated that approximately 132,878 dental offices are small businesses and that
approximately 116,014 of these small business dental offices could incur costs under the rule.
Because the number of small business dental offices that process amalgam is only 707 offices
less than the total dental offices subject to the rule (116,720), and cost-to-revenue impacts above
the thresholds are located in the lower revenue ranges, there is no difference between the cost-to-
revenue analysis performed for all dental offices and that performed for small entities.
To assess the potential for significant impact on these small businesses, EPA relied on the
method of the cost-to-revenue impact analysis as presented in Chapter 10.3.1, which used one
and three percent of revenue thresholds as impact measures. As described in that chapter, EPA
performed this analysis on two bases:
•	Excluding the baseline set-aside offices from the cost-to-revenue analysis.
•	Including the baseline set-aside offices in the cost-to-revenue analysis.
Table 10-20 summarizes the results for small entities from this analysis.
Table 10-20. Cost-to-Revenue Impact Analysis for Small Entities3
Offices with Cost Exceeding 1 Percent
of Revenue
Offices with Cost Exceeding 3 Percent
of Revenue
Technology-
No-Tech-


Technology-
No-Tech-


In-Place
in-Place
Total
Percentage
In-Place
in-Place
Total
Percentage
Excluding Baseline Set-Aside Offices from Analysis
156
652
808
0.7%
0
0
0
0.0%
Including Baseline Set-Aside Offices in Analysis
347
871
1,217
1.0%
35
139
174
0.2%
Source: U.S. EPA, 2016a
a - Results are the same for both the ADA National and Colorado distributions of chairs by office.
As shown in Table 10-20, with the baseline set-aside offices excluded from the analysis,
EPA estimates that 808 dental offices would incur costs exceeding one percent of revenue.39
These offices represent 0.7 percent of the small business offices estimated to incur costs under
the dental category rule. EPA estimates that no small entities would incur costs exceeding three
percent of revenue for the rule.
With the baseline set-aside offices included in the analysis, EPA estimates that 1,217
dental offices would incur costs exceeding one percent of revenue. These offices represent 1.0
percent of small business offices estimated to incur costs under the final dental category rule.
EPA estimates that 174 dental offices would incur costs exceeding three percent of revenue,
39 These findings do not vary by distribution of chairs by office.
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Chapter 10—Economic Impacts for the Dental Industry
representing 0.2 percent of small business offices estimated to incur costs under the final dental
category rule.
From this analysis, given the very small percentage of small business dental offices
potentially incurring costs exceeding the one percent and three percent of revenue thresholds,
EPA estimates that the final dental category rule would not impose a significant impact on a
substantial number of small entities (SISNOSE).
10.6 References
American Dental Association (ADA). 2009. American Dental Association. An Economic Study
of Expanded Duties of Dental Auxiliaries in Colorado. Beazoglou, et al. Document
Control Number (DCN) DA00149.
ADA. 2010. 2009 Survey of Dental Practice: Income from the Private Practice of Dentistry.
DCN DA00141.
ADA. 2016. Health Policy Institute Analysis of ADA Masterfile. Table 4: Supply of Dentists in
the U.S. by Practice, Research, or Administration Area, Dentists Working in Dentistry.
DCN DA00460.
Georgetown University. 2003. Safety Net Dental Clinic Manual. National Maternal and Child
Oral Health Resource Center. DCN DA00151 and DCN DA00154.
Pimpare, Justin. 2012. Dentists Who Certify They Neither Place Nor Remove Amalgam.
Memorandum. U.S. EPA Region 1. 25 January. DCNDA00161.
U.S. BLS. 2016. U.S. Bureau of Labor Statistics. Employment Cost Index for State and Local
Government. DCN DA00519.
U.S. Census Bureau. 2012a. Table EC1262SSSZ1: Health Care and Social Assistance: Subject
Series - Estab & Firm Size: Receipts/Revenue Size of Establishments for the U.S.: 2012.
DCN DA00507.
U.S. Census Bureau. 2012b. Table EC1262SSSZ3: Health Care and Social Assistance: Subject
Series - Estab & Firm Size: Single Unit and Multiunit Firms for the U.S.: 2012. DCN
DA00508.
U.S. EPA. 2000.Economic, Environmental, and Benefits Analysis of the Proposed Metal
Products and Machinery Rule (EPA-821-B-00-008). Office of Water. December. DCN
DA00251.
U.S. EPA. 2011. Information Collection Request: National Pretreatment Program OMB Control
No. 2040-0009, EPA ICR No. 0002.15. November. DCNDA00144.
U.S. EPA. 2016a. Economic Analysis for the Final Dental Amalgam Rule. MS Excel® File.
Office of Water. Washington, D.C. December. DCN DA00458.
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Chapter 10—Economic Impacts for the Dental Industry
U.S. EPA. 2016b. Memo on Institutional Facilities. Memorandum to the Public Record for the
Dental Category Final Rule. Office of Water. Washington, DC. December 5. DCN
DA00511.
U.S. EPA. 2016c. Dental Office Cost Calculations. MS Excel® File. Office of Water.
Washington, D.C. December. DCN DA00456.
U.S. EPA. 2016d. Control Authority Cost Calculations. MS Excel® File. Office of Water.
Washington, D.C. December. DCN DA00457.
Vandeven, J., and S. McGinnis. 2005. An Assessment of Mercury in the Form of Amalgam in
Dental Wastewater in the United States. Water, Air and Soil Pollution, 164:349-366.
DCN DA00163.
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Chapter 11—Pollutant Reduction Estimates
Chapter 11
Pollutant Reduction Estimates
The final rule establishes pretreatment standards based on proper operation and
maintenance of one or more amalgam separators compliant with the ISO 11143 standard (or its
equivalent) and two best management practices (BMPs). EPA's pollutant reduction methodology
assumes dental offices will use the required BMPs in combination with amalgam separators that
meet the 2008 ISO 11143 standard, the technology basis, to comply with the final rule.
EPA does not have office-specific discharge data for the approximately 117,000 dental
offices potentially subject to the final rule. Instead, EPA modeled the baseline, pre-rule
discharges of mercury and other metals based on nationwide estimates of amalgam restorations
and removals, and did not calculate the pollutant reductions on a per office basis. Rather, EPA
calculated average mercury (and other pollutant) loadings by dividing the total number of annual
procedures by the total number of dentists performing these procedures.40 This is the same
approach and data that EPA presented in its Health Services Industry Detailed Study (U.S. EPA,
2008). EPA did not receive comments on this part of the detailed study that would cause EPA to
reconsider its approach, and therefore, EPA did not change the overall methodology. The
following chapters describe the methodology in more detail.
11.1 National Estimate Of Annual Pollutant Loadings From Dental Offices
This chapter describes the methodology used to estimate national baseline pollutant
loadings generated at dental offices and discharged to publicly owned treatment works (POTWs)
and to surface waters.
11.1.1 National Estimate of Annual Mercury in Dental Office Wastewater
First, EPA estimated the amount of mercury potentially generated nationwide through
amalgam restorations (placements). EPA's main source of the data underlying all of the
estimates related to restorations is Vandeven and McGinnis, 2005. EPA estimated that 71 million
restorations are performed at dental offices annually and that these restorations require one
amalgam capsule per restoration.
Dental amalgam capsules used for restorations contain approximately 450 milligrams
(mg) of mercury. When placed in the patient's mouth, approximately 75 percent of the amalgam
is used (340 mg of mercury), with the remaining amount recycled or discarded as gray bag
waste. Of the amount used for restoration, an estimated 9 percent of the amalgam (30.6 mg of
mercury) enters the dental office wastewater as carvings and filings or other waste (Vandeven
and McGinnis, 2005). From these data, EPA estimated that dental offices generate a total of 2.4
40 Because this approach is based on the number of dentists, it includes those dentists both at offices and institutional
offices.
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Chapter 11—Pollutant Reduction Estimates
tons of mercury nationwide41 in their wastewaters from restorations (U.S. EPA, 2016). Table
11-1 presents how mercury waste is generated at dental offices during amalgam restorations.
Table 11-1. Mercury Waste Generation from the Restoration of Dental Amalgam
Process
Description
Total Mercury
Mercury used for
Filling
Waste Mercury
Waste Disposal
Amalgam
Restoration
71 million
procedures
per year
450 milligrams
(mg) per
capsule
340 mg
(75% of total
mercury)
31 mg (9% of
filling mercury) -
carvings and filings
during procedure
Rinsed into wastewater drain
2.4 tons per year from all procedures
110 mg (25% of total mercury) remains
in capsule
Recycled or discarded as gray bag waste
Sources: U.S. EPA, 2016; Vandeven and McGinnis, 2005.
Second, EPA modeled mercury generation from amalgam removals. As with restorations,
EPA's main source of the data underlying all of the estimates related to amalgam removals is
Vandeven and McGinnis, 2005. The removal rate of dental amalgam fillings is 710 removals per
general dentist each year and 440 removals per specialty dentist each year (Vandeven and
McGinnis, 2005). Based on 2015 data, there are 195,722 total dentists: 79 percent general
dentists and 21 percent specialty dentists (ADA, 2016). EPA assumed that 39 percent of general
dentists place or remove amalgam based on type of specialty practice (ADA, 2016; U.S. EPA,
2016). Based on this information, EPA estimates that approximately 117 million amalgam
removals occur each year (U.S. EPA, 2016).
Dental amalgam removed from patients contains approximately 300 mg of mercury per
filling. An estimated 90 percent of the amalgam enters the dental office wastewater (270 mg of
mercury per filling), with the remainder lost as air particulates from grinding or handled as dry
waste (i.e., gray bagged). EPA estimated dental offices generate 34.8 tons of mercury in their
wastewaters from amalgam filling removals each year42 (U.S. EPA, 2016). Table 11-2 presents
how mercury waste is generated at dental offices during amalgam removals.
Table 11-2. Mercury Waste Generation from the Removal of Dental Amalgam
Process
Description
Total Mercury
Waste Mercury
Waste Disposal
Amalgam
Removal
117 million
procedures
per year
300 milligrams
(mg) per
removed filling
270 mg
(90% of total mercury)
Rinsed into wastewater drain
34.8 tons per year from all procedures
30 mg (10% of total mercury)
Dry waste disposal/gray bag waste or air
particulates
Sources: U.S. EPA, 2016; Vandeven and McGinnis, 2005.
41 71 million restorations times 31 mg per filling.
42117 million amalgam filling removals times 270 mg per removal.
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Chapter 11—Pollutant Reduction Estimates
Summing the total mercury loading from the annual number of restorations and removals,
EPA estimated dental offices generate 37.2 tons of mercury annually as part of dental office
wastewaters, see Table 11-3.
Table 11-3. Annual Untreated Mercury Generation from the Restoration and
Removal of Dental Amalgam
Description
Number of
Procedures
Mercury in
Dental Office
Wastewater per
Procedure
Mercury in Dental
Office Wastewater
(Untreated)
Notes
Amalgam
Restorations
71 million
31 milligrams
(mg)
2.4 tons (U.S.)
Estimate mercury entering wastewater
based on number of restoration
procedures. Amalgam capsule contains
450 mg of mercury. Assume 75 percent
of the capsule is used for restoration (340
mg). During placement, 9 percent of the
mercury (31 mg) is rinsed into
wastewater drain as carvings or filings.
Amalgam
Removals
117 million
270 mg
34.8 tons (U.S.)
Estimate by number of general dentists
and specialists who perform removals
and average number of removals per
dentist and per specialist. Assume 90
percent of mercury removed (270 mg) is
part of the dental office wastewater.
TOTAL


37.2 tons

Sources: U.S. EPA, 2016; Vandeven and McGinnis, 2005.
11.1.2 National Estimate of Annual Baseline Mercury Discharges from Dental Offices
to POTWs
EPA estimated that within the 116,719 dental offices potentially subject to the final rule,
13,685 offices do not place or remove amalgam and therefore do not generate amalgam
wastewater (Chapter 10.1.2). Therefore, the remaining 103,034 offices collectively generate 37.2
tons of mercury in their wastewaters. This equates to 0.72 pounds per dental office. However, as
explained earlier, some dental offices currently employ treatment technologies that will reduce
this mercury prior to discharge. EPA assumed the following with respect to current technologies
in place:
•	Twenty percent use chair-side traps only (Vandeven and McGinnis, 2005): 20,607
dental offices.
•	48,292 dental offices use amalgam separators (U.S. EPA, 2016).
•	The remaining 34,135 dental offices use chair-side traps and vacuum filters.
The mercury removal efficiency of the chair-side trap is 68 percent, and the mercury
removal efficiency of the chair-side trap plus vacuum filter is 78 percent (Vandeven and
McGinnis, 2005). After accounting for mercury reductions achieved through existing chair-side
traps, vacuum filters, and amalgam separators, as appropriate, EPA estimated that the
approximately 55,000 dental offices without amalgam separators collectively discharge a total of
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Chapter 11—Pollutant Reduction Estimates
10,200 pounds (5.09 tons) of mercury to POTWs per year. The approximately 48,300 dental
offices with amalgam separators collectively discharge approximately 54 pounds (0.027 tons) of
mercury to POTWs per year. Thus, EPA calculated the current nationwide annual baseline
loading of mercury discharged to POTWs from dental offices to be 5.12 tons, out of a total of the
37.2 tons originally generated (U.S. EPA, 2016).
Table 11-4 summarizes the use and mercury removal efficiencies of wastewater treatment
technologies at dental offices.
Table 11-4. Dental Office Use and Mercury Removal Efficiency by Treatment Technology
Treatment Technology
Number of Dental Offices
Removal Efficiency for
Total Mercury
Chair-Side Traps Only
20,600
68%
Chair-Side Traps and Vacuum Filter Only
34,100
78%
Amalgam Separator
48,300
99.3%
Total
103,000
--
Sources: U.S. EPA, 2016; Vandeven and McGinnis, 2005.
11.1.3 National Estimate of Annual Non-Mercury Amalgam Metals in Dental Offices
Wastewater
In addition to mercury, dental amalgam contains other metal constituents. EPA estimated
pollutant loadings for four other metals contained in dental amalgam: silver, tin, copper, and
zinc. The composition of amalgam is approximately 49 percent mercury, 35 percent silver, 9
percent tin, 6 percent copper, and 1 percent of zinc (Massachusetts Water Resources Authority,
2001). Using the mercury generation estimates in Chapter 11.1.1, EPA estimated the generation
of metal waste in dental office wastewater (see Table 11-5).
Table 11-5. Calculation of Annual Untreated Non-Mercury Metal Generation from the
Restoration and Removal of Dental Amalgam
Description
Pollutant in
Dental Office
Wastewater
Per Procedure
Annual Loading
(Untreated)
Notes
Amalgam
Restorations
Mercury
31 milligrams
(mg)
2.4 tons (U.S.)
Estimate non-mercury metals entering
wastewater based on ratio of amalgam
composition: 49 percent mercury and 51
percent non-mercury metals.
Non-Mercury
Metals
32 mg
2.5 tons (U.S.)
Amalgam
Removals
Mercury
270 mg
34.8 tons (U.S.)
Non-Mercury
Metals
281 mg
36.2 tons (U.S.)
Sources: U.S. EPA, 2016.
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Chapter 11—Pollutant Reduction Estimates
11.1.4	National Estimate of Annual Baseline Discharges of Non-Mercury Amalgam Metals
from Dental Offices to POTWs
As with mercury pollutant loadings, EPA assumed chair-side traps and vacuum filters
will result in 68 and 78 percent collection of all amalgam metals, respectively. EPA also
assumed a 99.3 percent removal of all amalgam metals at offices with amalgam separators in
place. Using the same methodology as described for mercury in Chapter 11.1.2 to calculate
baseline pollutant loadings, EPA estimated the non-mercury metal mass loading generated by
amalgam restorations as 2.5 tons per year. EPA similarly estimated the non-mercury metal mass
loadings generated by amalgam removals as 36.2 tons per year. After accounting for existing
technologies at dental offices, EPA calculated the current nationwide annual baseline loading of
non-mercury metals discharged to POTWs from dental offices to be 5.3 tons, out of a total of
38.7 tons originally generated (U.S. EPA, 2016).
11.1.5	Total Annual Baseline Discharges to POTWs
After accounting for existing technologies at dental offices, EPA estimated dental offices
collectively discharge 5.1 tons of mercury and 5.3 tons of additional metals to POTWs per year
for a total discharge to POTWs of 10.4 tons annually.
11.2	National Estimate Of Annual Pollutant Reductions To POTWs Associated
With The Final Dental Category Rule
EPA estimated that the approximately 54,700 dental offices without technology in place
will install amalgam separators that meet the 2008 ISO 11143 standard with a median removal
efficiency of 99.3 percent as a result of the final rule for the dental category. The combination of
chair-side traps, vacuum filters and separators would then achieve 99.8 percent removal of total
solids (i.e., all metals) from the dental wastewater (U.S. EPA, 2016). This would result in
reduction of total mercury discharges to POTWs by 5.06 tons. Because dissolved mercury
accounts for much less than 1 percent of total mercury (Stone, 2004), and because amalgam
separators are not effective in removing dissolved mercury, EPA assumed the dissolved mercury
contribution and associated reduction in loadings to be negligible.
Similarly, EPA estimated a reduction of non-mercury metal (i.e., silver, tin, copper, and
zinc) discharges to POTWs of approximately 5.27 tons. Again, EPA assumes the dissolved metal
content to be negligible.
Accordingly, the final rule would annually reduce mercury discharges by 5.06 tons and
other metal discharges by 5.27 tons for a total annual reduction to POTWs of 10.33 tons.
11.3	National Estimate Of Annual Pollutant Reductions To Surface Waters
Associated With The Final Dental Category Rule
In order to evaluate final discharges of mercury (and other metals) to waters of the United
States by POTWs, EPA used its 50 POTW Study (U.S. EPA, 1982) to calculate POTW removals
of each metal (see Chapter 5 for details). As explained above, at baseline and prior to
implementation of the final rule, EPA estimated that, collectively, dental offices discharge 5.1
11-5
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Chapter 11—Pollutant Reduction Estimates
tons43 of dental mercury annually to POTWs. Based on the 50 POTW Study, EPA estimates that
POTWs remove 90.2 percent of the 5.1 tons of mercury from the wastewater. Thus, POTWs
collectively discharge 1,003 pounds of dental mercury to surface waters annually.
Under the final dental category rule, over 98 percent of mercury solids currently
discharged annually to POTWs will be removed prior to the POTW. The POTWs then further
remove 90.2 percent of total mercury from the wastewater. This reduces the total amount of
dental mercury discharged from POTWs nationwide to surface water to 11 pounds annually. In
other words, discharges of mercury to waters of the United States from POTWs are expected to
be reduced by 992 pounds per year44 as a result of the final rule.
Based on the 50 POTW Study, POTWs remove the following from wastewater prior to
discharge:
•	88 percent of total silver;
•	43 percent of total tin;
•	84 percent of total copper; and
•	79 percent of total zinc.
At baseline, EPA estimates that dental offices discharge 5.4 tons of non-mercury
amalgam metals to POTWs annually. After treatment at the POTW, POTWs collectively
discharge 2,178 pounds of non-mercury amalgam metals to surface waters annually. Following
compliance with the final dental category rule, the non-mercury amalgam metal discharges from
POTWs to surface waters will be approximately 24 pounds, a reduction of 2,153 pounds.45 This
results in the total reduction of amalgam metals (mercury and non-mercury) to waters of the
United States by an estimated 3,146 pounds (U.S. EPA, 2016).
11.4 References
ADA. 2016. Supply of Dentists in the U.S. 2001 - 2015. MS Excel® file. Document Control
Number (DCN) DA00460.
Massachusetts Water Resources Authority. 2001. Amalgam Composition in Typical Dental
Fillings (figure). DCN DA00131.
Stone, M.E. 2004. The Effect of Amalgam Separators on Mercury Loading to Wastewater
Treatment Plants. Journal of the California Dental Association, 32(7):593-600. DCN
DA00018.
43	This may be a conservative assumption, particularly where sewers are designed for overflows (as is the case for
combined sewers), or where sewers have overflows as a result of improper maintenance or accidents and natural
disasters (e.g., floods or earthquakes).
44	Dissolved mercury accounts for a portion of surface water discharges, because amalgam separators do not remove
dissolved mercury.
45	Numbers are rounded; therefore, subtraction of baseline and post-compliance pollutant removals may differ
slightly from pollutant reduction value.
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Chapter 11—Pollutant Reduction Estimates
U.S. EPA. 1982. Fate of Priority Pollutants in Publicly Owned Treatment Works. EPA 440/1-
82/303. Office of Water. Washington, DC. September. DCNDA00244.
U.S. EPA. 2008. Health Services Industry Detailed Study: Dental Amalgam. EPA-821-R-08-014.
Office of Water. Washington, DC. August. DCN DA00057.
U.S. EPA. 2016. Dental Office Cost Calculations. MS Excel® file. Office of Water. Washington,
DC. December. DCN DA00456.
Vandeven, J., and S. McGinnis. 2005. An Assessment of Mercury in the Form of Amalgam in
Dental Wastewater in the United States. Water, Air, and Soil Pollution, 164:349-366.
DCN DA00163.
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Chapter 12—Cost-Effectiveness Analysis
Chapter 12
Cost-Effectiveness Analysis	
EPA traditionally defines cost-effectiveness as the total incremental annualized cost of a
pollution control option per total incremental toxic pound-equivalent (i.e., pound of pollutant
adjusted for relative toxicity) removed by that control option. EPA uses the cost-effectiveness
analysis primarily in comparing the removal efficiency of regulatory options under consideration
for a rulemaking. A secondary use is to compare the cost-effectiveness of the final rule to those
for effluent limitations guidelines and standards (ELGs) for other industries. This definition
includes the concepts discussed in this chapter.
12.1 Total Incremental Annualized Compliance Costs
The cost-effectiveness analysis uses the estimated total annual costs of complying with
the final rule. As described in Chapter 10.2.3, EPA developed two estimates of incremental
costs, reflecting different distributions of numbers of chairs in dental offices. EPA adjusts the
compliance costs to 1981 dollars to allow for comparison with cost-effectiveness values for other
promulgated regulations for different industries. EPA adjusted the value using the Bureau of
Economic Analysis GDP Implicit Price Deflators,46 and calculates this adjustment factor as
follows:
Adjustment factor = (1981$) - (2016$) = 48.52 - 110.39 = 0.440
Table 12-1 shows the estimated annualized compliance costs converted to 1981 dollars.
Table 12-1. Annualized Compliance Costs at Promulgation Year
Dental Office
Distribution Data Source
Millions; 2016$
Conversion Factor
Millions; 1981$
ADA Colorado Survey
$53.5
0.44
$23.5
ADA National Survey
$54.8
$24.1
Source: U.S. EPA, 2016a
12.2 Toxic Weighting Factors
Because each pollutant differs in its potential harmful effects on human and aquatic life,
EPA uses a toxic weighting factor (TWF) specific to each pollutant to calculate a toxicity-
normalized pollutant removal value for use in the cost-effectiveness analysis.47 The toxic
46	EPA typically uses the Engineering News Record Construction Cost Index. However, this approach is not
appropriate for this rule because the technology option does not require construction.
47	See U.S. EPA, 2011 for details on toxic weighting factors.
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Chapter 12—Cost-Effectiveness Analysis
weighting factor for each pollutant measures its toxicity relative to copper,48 with more toxic
pollutants having higher toxic weights. The use of toxic weights allows EPA to express the
removals of different pollutants on a constant toxicity basis as toxic-weighted-pound-equivalents
(lb-eq). In the case of indirect dischargers, the removal also accounts for the effectiveness of
treatment at publicly owned treatment works (POTWs) and reflects the toxic-weighted-pound-
equivalents after POTW treatment. Table 12-2 lists the TWFs for the pollutants found in dental
discharges.
Table 12-2. Toxic Weighting Factors for Pollutants in Dental Amalgam
Pollutant
Toxic Weighting Factor
Total mercury
110
Silver
16.47
Tin
0.301
Copper
0.623
Zinc
0.047
Source: U.S. EPA, 2016b
12.3 Calculation Of Annual Total Incremental Pound-Equivalents Removed To
Surface Waters
EPA estimated the annual reduction in pollutant loadings nationwide to waters of the
United States associated with the final rule for each pollutant identified in dental amalgam.
Because this final rule is for indirect discharges, this estimate accounts for discharge
reductions that occur at the publicly owned treatment works (POTW). See Chapter 11 of this
document for further information on how loadings were calculated. EPA adjusts the reductions in
a pollutant's discharges for an option, or pollutant removals, for toxicity by multiplying the
estimated removal quantity for each pollutant by its TWF. EPA refers to these adjusted removals
as toxic-weighted pound-equivalents (TWPEs). EPA summed the TWPE reductions for each
pollutant to estimate the total annual incremental pound-equivalent reductions for the final rule.
Table 12-3 presents the estimate of individual and total annual incremental pound-equivalent
removals from surface waters for the final rule.
48 When EPA first developed TWFs in 1981, it chose the copper freshwater chronic aquatic life criterion of 5.6 |ig/L
as the benchmark scaling factor for deriving TWFs because copper was a common and well-studied toxic chemical
in industrial waste streams. Consequently, the basic equation for deriving the TWF for any chemical is: TWF = 5.6
|ig/L / Aquatic Life Value (|ig/L) + 5.6 |ig/L / Human Health Value (|ig/L). The chronic freshwater aquatic life
criterion for copper, however, lias been revised three times since it was first published in 1980 due to advances in
the scientific understanding of its toxic effects. Thus, when calculating the TWF for copper, EPA normalizes the
1998 chronic freshwater aquatic life copper criterion of 9.0 |ig/L to the original 1980 copper criterion of 5.6 |ig/L by
dividing 5.6 |ig/L by 9.0 |ig/L and adding the quotient to 5.6 |ig/L divided by the copper human health value of 4444
|ig/L. which results in a copper TWF of 0.623.
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Chapter 12—Cost-Effectiveness Analysis
Table 12-3. Total Incremental Pound-Equivalents Removed
from Surface Water Discharges3

Incremental Removals

Incremental Removals
Pollutant
from Baseline (lbs/yr)
Toxic Weighting Factors
from Baseline (lb-eq/yr)
Total mercury
992
110
109,146
Silver
848
16.47
13,961
Tin
1,067
0.301
321
Copper
196
0.623
122
Zinc
43.1
0.047
2.02
Total


123,552
Source: U.S. EPA, 2016a; U.S. EPA, 2016b
a - Numbers shown are rounded; multiplying values across the first two columns will not exactly equal the value
in the last column
12.4 Cost-Effectiveness Results
Table 12-4 presents the cost-effectiveness data and results. The cost-effectiveness value
for the final rule is $190 to $195 per lb-eq (1981$).
Table 12-4. PSES Cost-Effectiveness Analysis
Dental Office Distribution Data Source
Pre-Tax Total
Annualized Costs
(Millions; 1981$)
Removals (lbs-eq)
Average Cost-
Effectiveness (1981$)
ADA Colorado Survey
$23.5
123,552
$190
ADA National Survey
$24.1
123,552
$195
Source: U.S. EPA, 2016a
EPA presents cost effectiveness in 1981 dollars as a reporting convention. This allows
EPA to compare the cost-effectiveness of various ELGs. EPA calculates cost-effectiveness as the
ratio of pre-tax annualized costs of a rule to the annual pounds-equivalent removed. Average
cost-effectiveness can be thought of as the increment between no regulation and the rule. The
technology basis for PSES in this final rule has a cost-effectiveness ratio of $190 to $195 per lb-
equivalent. This cost-effectiveness ratio falls within industry comparisons of PSES cost-
effectiveness. A review of approximately 25 of the most recently promulgated or revised
categorical pretreatment standards found that PSES cost effectiveness ranges from approximately
$1 per lb-equivalent (Inorganic Chemicals) to $380 per lb-equivalent (Transportation Equipment
Cleaning) in 1981 dollars.
12.5 References
U.S. EPA. 2011. Technical Support Document for the 2010 Effluent Guidelines Program Plan.
EPA-820-R-10-021. Office of Water. Washington, DC. Document Control Number
(DCN) DA00225.
U.S. EPA. 2016a. Economic Analysis for the Final Dental Amalgam Rule. MS Excel® File.
Office of Water. Washington, D.C. December. DCN DA00458.
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Chapter 12—Cost-Effectiveness Analysis
U.S. EPA. 2016b. Dental Office Cost Calculations. MS Excel® File. Office of Water.
Washington, D.C. December. DCN DA00456.
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Chapter 13—Environmental Impacts of Dental Mercury Discharges
Chapter 13
Environmental Impacts of Dental Mercury Discharges
Aside from mercury, other constituents of dental amalgam include the metals 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
biomagniftes in aquatic food chains. For wastewater mercury discharges, the major route for
human exposure to mercury discharged in wastewater is the consumption of mercury-
contaminated fish.
13.1 Mercury In Dental Wastewater
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 (methylmercury, or MeHg) (Stone et al., 2002). Table 13-1 presents the mean
concentrations of mercury species measured in wastewater samples collected at the dental chair.
Nearly all (>99.6 percent) of dental mercury discharges are in solid form (elemental mercury
bound to amalgam particulate).
Table 13-1. Mean Concentrations of Mercury Species in Dental Wastewater
Mercury Form
Measured Concentration
Percent of Total Mercury
MeHg (methylmercury)
277.74 nanograms/liter (ppt)
0.0013%
HgO (unbound elemental mercury)
24.06 micrograms/liter (ppb)
0.112%
Hg+2 (ionic mercury)
54 micrograms/liter (ppb)
0.252%
HgO (elemental mercury bound to
amalgam particulate)
21.360 milligrams/liter (ppm)
99.6%
Source: Stone, 2004.
While dissolved mercury (MeHg, unbound HgO, Hg+2), makes up less than one percent
of the total mercury in dental wastewater, there is increasing interest in the causes of dissolution
and the extent to which dissolved mercury is present in dental wastewater. Dissolved mercury is
a concern because elemental and ionic mercury can be converted to form additional
methylmercury by bacteria, such as Desirffobacteraceae and Desulfovihrionaceae, which are
present in wastewater (ACS, 2008). Methylmercury is particularly toxic to humans due to its
ability to bioaccumulate in fish. When humans consume methylmercury, it targets the nervous
system and can hinder a person's ability to walk, talk, see, and hear. Extreme cases of
methylmercury poisoning can result in coma or death (WIDNR, 1997).
Researchers have detected concentrations of methylmercury in dental wastewater that are
orders of magnitude higher than background methylmercury concentrations measured in
environmental samples from open oceans, lakes, and rainfall. Concentrations of methylmercury
in dental wastewater ranged from 0.90 to 26.77 milligrams per liter (mg/L). Such dissolved
mercury concentrations can be high enough to violate local mercury discharge limits (Stone,
2004). In comparison, concentrations in environmental samples have ranged from 0.05 to 10.0
13-1
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Chapter 13—Environmental Impacts of Dental Mercury Discharges
nanograms per liter (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).
13.2	Dental Mercury Fate And Transport
The form of mercury discharged from dental practices is important to publicly owned
treatment works (POTWs) because it can affect their 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. For the pass-through analysis conducted as part of this rulemaking (see Chapter
5.3), EPA used a 90 percent removal rate for total mercury.
POTWs manage their wastewater treatment sludge (biosolids) through beneficial reuse
(60 percent) and via disposal (40 percent). Disposed biosolids are typically incinerated (22
percent of all biosolids) or disposed of in a landfill (18 percent of all biosolids) (U.S. EPA,
1999). Mercury is a relatively volatile metal that can be converted to a gas by incineration and
emitted to the atmosphere. Once in the atmosphere, mercury is deposited into lakes and streams
by rainfall. (WIDNR, 1997). In contrast, solid mercury particles disposed of in a landfill are
unlikely to be released into the environment.
13.3	Environmental Assessment
EPA conducted a literature review concerning potential environmental impacts associated
with mercury in dental amalgam discharged to surface water by POTWs (U.S. EPA, 2011).
Studies indicate that dental offices are the largest source of mercury entering POTWs. The total
annual baseline discharge of dental mercury to POTWs is approximately 10,239 pounds (5.1
tons): 10,198 pounds are in the form of solid particles (99.6 percent) and 41 pounds (0.4 percent)
are dissolved in the wastewater (U.S. EPA, 2016). Through POTW treatment, approximately 90
percent of dental mercury is removed from the wastewater and transferred to sewage sludge. The
10 percent of dental mercury not removed by POTW treatment is discharged to surface water.
EPA estimates that POTWs annually discharge approximately 1,003 pounds of dental mercury
nationwide.
13.3.1 Mercury in Surface Water Discharges
Environmental assessment of impacts associated with POTW discharges of dental
mercury is complicated by uncertainties about the fate and transport of mercury in aquatic
environments. The elemental form of mercury used in dentistry has low water solubility and is
not readily absorbed when ingested by humans, fish, or wildlife. However, elemental mercury
may be converted into highly toxic methylmercury in aquatic environments by certain forms of
anaerobic sulfate-reducing bacteria. Methylmercury is easily absorbed into muscle and fat
tissues, but it is not readily excreted due to its low water solubility. Methylmercury thus has high
potential to become increasingly concentrated up through the aquatic food chains, as larger fish
eat smaller fish. Fish commonly eaten by humans may have methylmercury levels 100,000 times
that of ambient water (Chin, et al., 2000).
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Chapter 13—Environmental Impacts of Dental Mercury Discharges
The neurological effects of eating methylmercury-contaminated fish are well documented
(WIDNR, 1997). Developmental effects to fetuses, infants, children, and fish consumption by
women of childbearing age are of special concern. Neurological effects from predation of
methylmercury contaminated fish have been documented to occur in wild populations of fish,
birds, and mammals in many areas of the United States (WIDNR, 1997). A plausible link has
been identified between anthropogenic sources of mercury (e.g., coal combustion) in the United
States and methylmercury in fish. However, fish methylmercury concentrations also result from
existing background concentrations of mercury, which may consist of mercury from natural
sources, mercury re-emitted from the oceans or soils, or atmospheric deposition of mercury in
the United States from sources in other countries. Given the current scientific understanding of
the environmental fate and transport of mercury, it is not possible to quantify how much of the
methylmercury in fish consumed by the U.S. population is contributed by U.S. emissions relative
to international mercury sources or natural mercury sources.
EPA was unable to assess the environmental impacts of dental mercury discharged by
POTWs due to insufficient data needed to evaluate several fundamental factors about the
discharge, fate, and transport of dental mercury in aquatic environments, including: the degree
and geographic extent of dental mercury methylation in aquatic environments, the amount of
methylated dental mercury that is taken up by fish and wildlife, the human consumption rates of
fish contaminated with methylated dental mercury, and the extent and magnitude of naturally-
occurring mercury in aquatic environments.
13.3.2 Mercury in Biosolids
The Clean Water Act regulations known as Standards for Use and Disposal of Sewage
Sludge, 40 CFRPart 503, control the land application, surface disposal, and incineration of
sewage sludge generated by POTWs. Of the 11.2 billion dry pounds of sewage sludge generated
annually, about 60 percent, or 6.7 billion pounds, are treated to produce biosolids for beneficial
use as a soil amendment and applied to about 0.1 percent of agricultural lands in the United
States (National Research Council, 2002). EPA estimates that approximately 5,500 pounds per
year of dental mercury are contained in land-applied biosolids. Nevertheless, the mercury content
of land applied biosolids has been documented to be well below the risk-based pollutant
concentration limits set by 40 CFR 503.
Approximately 18 percent, or 2 billion pounds, of the sewage sludge generated annually
by POTWs are surface disposed in sewage sludge mono-fills or municipal landfills (U.S. EPA,
1999). Approximately 1,700 pounds per year of dental mercury are contained in surface disposed
sewage sludge. Pollutant discharge limits and monitoring requirements for surface disposed
sewage sludge mono-fills are set by 40 CFR 503 and by 40 CFR 258 for municipal landfills.
There may be additional state or local regulations that are more stringent than the federal
biosolids regulations.
The remaining 22 percent, or 2.5 billion pounds, of sewage sludge generated annually by
POTWs is disposed of through incineration (U.S. EPA, 1999). Incineration of sewage sludge
emits an estimated 35 pounds of dental mercury to the atmosphere annually, of which
approximately 11.5 pounds are deposited within the conterminous United States (U.S. EPA,
1997; U.S. EPA, 2005a; U.S. EPA, 2005b; and U.S. EPA, 2009). Approximately 2,000 pounds
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Chapter 13—Environmental Impacts of Dental Mercury Discharges
per year of dental mercury are contained in incinerated sewage sludge. 40 CFR 503, subpart E,
sets requirements for the incineration of mercury and other toxic metals in sludge. For mercury,
subpart E provides that incineration of sludge must meet the requirements of the National
Emissions Standards for Mercury in subpart E of 40 CFR 61.
13.3.3 Environmental Benefits of the Final Rule
While EPA did not perform an environmental benefits analysis of the final rule, due to
insufficient data about the aquatic fate and transport of dental mercury discharged by POTWs,
EPA was able to assess the qualitative environmental benefits based on existing information. For
example, EPA identified studies that show that decreased point-source discharges of mercury to
surface water result in lower methylmercury concentrations in fish. Moreover, several studies
quantify economic benefits from improved human health and ecological conditions resulting
from lower fish concentrations of methylmercury (U.S. EPA, 2011). The final pretreatment
standards will produce human health and ecological benefits by reducing the estimated annual
nationwide POTW discharge of dental mercury to surface waters from 1,003 pounds to 11
pounds (U.S. EPA, 2016). In addition, the decreased discharges to POTWs will result in a
decrease of mercury in biosolids. EPA is unable to quantify the nationwide benefits of reducing
the releases of mercury to air, landfills, air, surface water, and groundwater as a result of reduced
mercury in biosolids that are subsequently incinerated, landfilled, and land applied.
13.4 References
ACS (American Chemical Society). 2008. Dental Offices Contribute to Methylmercury Burden:
Bacteria That Methylate Mercury Thrive in Wastewater Found Downstream from Dental
Traps. Environmental Science & Technology Online News. March 12. Document Control
Number (DCN) DA00201.
Chin, G., J. Chong, A. Kluczewska, A. Lau, S. Gorjy, and M. Tennant. 2000. The Environmental
Effects of Dental Amalgam. Australian Dental Journal, 45: 246-249. DCNDA00312.
National Research Council (NRC). 2002. Biosolids Applied to Land: Advancing Standards and
Practices. Division on Earth and Life Sciences. Washington, DC. July. DCN DA00257.
Stone, M.E., et al. 2002. Determination of Methyl Mercury in Dental-Unit Wastewater. Dental
Materials, 19:675-679. DCNDA00173.
Stone, M.E. 2004. The Effect of Amalgam Separators on Mercury Loading to Wastewater
Treatment Plants. Journal of the California Dental Association, 32(7):593-600. DCN
DA00018.
U.S. EPA. 1997. Mercury Study Report to Congress. Volume VII: Characterization of Human
Health and Wildlife Risks from Mercury Exposure in the United States. EPA-452/R-97-
009. Office of Air Quality Planning and Standards and Office of Research and
Development. DCN DA00256.
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Chapter 13—Environmental Impacts of Dental Mercury Discharges
U.S. EPA. 1999. Biosolids Generation, Use, and Disposal in the United States. EPA 530-R-99-
009. Office of Solid Waste. September.
http://www.epa.gov/osw/conserve/rrr/composting/pubs/biosolid.pdf. DCN DA00303.
U.S. EPA. 2005a. Revision of December 2000 Regulatory Finding on the Emissions of
Hazardous Air Pollutants from Electric Utility Steam Generating Units and the Removal
of Coal- and Oil-Fired Electric Utility Steam Generating Units From the Chapter 112(c)
List; Final Rule. 40 CFR Part 63. DCN DA00319.
U. S. EPA. 2005b. Regulatory Impact Analysis of the Clean Air Mercury Rule: Final Report.
Office of Air Quality Standards and Planning. Research Triangle Park, NC. EPA-452/R-
05-003. DCN DA00283.
U.S. EPA. 2009. Targeted National Sewage Sludge Survey: Sampling and Analysis Technical
Report. Office of Water. Washington, DC. January. DCNDA00299.
U.S. EPA. 2011. Literature Review of the Impacts of Mercury from Dental Amalgam in
Wastewater. Office of Water. Washington, DC. DCNDA00148.
U.S. EPA. 2016. Dental Office Cost Calculations. MS Excel® file. Office of Water. Washington,
DC. December. DCN DA00456.
WIDNR (Wisconsin Department of Natural Resources). 1997. Wisconsin Mercury Sourcebook.
DCN DA00202.
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Chapter 14—Non-Water-Quality Environmental Impacts
Chapter 14
Non-Water-Quality Environmental Impacts	
The elimination or reduction of one form of pollution has the potential to aggravate other
environmental problems, an effect frequently referred to as cross-media impacts. Sections 304(b)
and 306 of the Clean Water Act (CWA) require EPA to consider non-water quality
environmental impacts (NWQEIs), including energy impacts, associated with effluent limitations
guidelines and standards (ELGs). To comply with these requirements, EPA considered the
potential impact of the technology basis on energy consumption, air pollution, and solid waste
generation.
As shown below, EPA anticipates that the rule would produce minimal non-water quality
environmental impacts and as such determined they are acceptable. The chapters below
summarize the NWQIs associated with the dental rule requirements.
14.1 Energy Requirements
Net energy consumption considers the incremental electrical requirements associated
with operating and maintaining dental amalgam separators used in combination with BMPs that
form the technology basis for the standard. As described in Chapter 5, the wastewater treatment
system at dental offices include the chair-side trap, vacuum pump with filter, and amalgam
separator. Dental vacuum systems operate at a typical vacuum level of six to eight inches
mercury and a typical airflow of seven standard cubic feet per minute per chair-side high volume
inlet. Excess amalgam from new fillings, as well as amalgam from removed restorations, is
rinsed into the chair-side drain. Amalgam separators typically use sedimentation, either alone or
in conjunction with filtration, to remove solids in the waste stream. Most separators rely on
gravity or the suction of the existing vacuum system to operate, and do not require an additional
electrical power source. A few models do require a 110-volt outlet or come with a pump as part
of their operation (McManus and Fan, 2003; USAF, 2011). Additionally, some separators have
warning indicators that require a battery or power source. Neither of these pose any considerable
energy requirements. As a result, EPA expects operation of an amalgam separator would pose
negligible additional energy requirements on the existing vacuum pump.
Some units described in the literature may require small pumps to remove settled effluent
from the separator (McManus and Fan, 2003). EPA found that these pumps are designed to
operate only at the end of the day or overnight, when the vacuum system is turned off. Any
incremental energy requirements in those cases where a small supplemental pump is installed
would be negligible compared to the energy demands of the vacuum pump. Moreover, the
addition of an amalgam separator is likely to reduce energy consumption at dental offices that do
not currently employ an amalgam separator as it will prevent small particles from impeding the
vacuum pump impeller. Just like a fan blade, a clean impeller is more efficient than a dirty
impeller, and thus will draw less energy (Shelton & Bodman, 1995; Jacobsen & Chastain, 1994;
Huyser, 2016). Based on this evaluation, EPA concluded there will be no significant non-water-
quality environmental impacts associated with the energy requirements for the final rule.
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Chapter 14—Non-Water-Quality Environmental Impacts
14.2	Solid Waste Generation
In the absence of amalgam separators, a portion of the amalgam rinsed into chair-side
drains is collected by chair-side traps and a portion of the amalgam suctioned into the vacuum
line is collected by vacuum pump filters. The remainder is discharged to the publicly owned
treatment works (POTW), where approximately 90 percent is removed from the wastewater and
becomes part of the POTW sludge; the sludge may be land applied, disposed of in landfills or
mono-fills, or incinerated. The final rule is expected to increase the use of amalgam separators
nationwide—EPA expects almost 55,000 dental offices to install amalgam separators to comply
with the final rule (see Table 10-2). Currently, just over 48,000 dental offices have separators
installed (see Table 10-2). With the increased use of amalgam separators, there will be a
corresponding increase in collection and recycling of used amalgam from spent canisters. EPA
expects the operation and maintenance requirements associated with the amalgam separator
compliance option included in the final rule will further promote recycling as the primary means
of amalgam waste management, because many amalgam separator manufactures and dental
office suppliers have begun offering waste handling services that send dental amalgam waste to
resorting and recycling facilities. Nationally, EPA expects less dental amalgam will be
discharged to POTWs leading to reductions in the amount of mercury discharged to surface
waters and the amount of mercury currently land-applied, landfilled, or released to the air during
incineration of sludge. Instead, EPA expects that the waste will be collected in separator
canisters and recycled. After the amalgam containing waste has been recycled, the canisters are
either recycled or landfilled. For purposes of assessing the incremental solid waste generation,
EPA conservatively assumes all of the canisters are landfilled. EPA found that if each dental
office generated an average of 2 pounds of spent canisters per year, the total mass of solid waste
generated would still comprise less than 0.0001 percent of the 254 million tons of solid waste
generated by Americans annually (U.S. EPA, 2013). Based on this evaluation of solid waste
generation, EPA concluded that there will not be a significant incremental non-water-quality
environmental impact associated with solid waste generation as a result of the final rule.
14.3	Air Emissions
While unbound mercury is highly volatile and can easily evaporate into the atmosphere,
an estimated 99.6 percent of dental mercury discharges are in solid bound form (i.e., elemental
mercury bound to amalgam particles) (Stone, 2004). Because nearly all dental mercury is bound
to solid particles, it likely will not volatilize to the atmosphere. Other metals contained in
mercury amalgams (silver, tin, copper, zinc, indium, and palladium) are much less volatile than
mercury and are also in solid bound form and are also not likely to volatilize to the atmosphere.
Therefore, EPA expects the final rule will not pose any increases in air pollution. In addition,
because particulate mercury is removed prior to the generation of biosolids by POTWs, the
portion of biosolids that is incinerated will produce less mercury in the air emissions. However,
EPA is unable to quantify the reduction in air emissions as a result of less mercury in the
biosolids that are incinerated. EPA concluded that there will be no significant non-water-quality
environmental impacts associated with air emissions as a result of the final rule.
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Chapter 14—Non-Water-Quality Environmental Impacts
14.4 References
Huyser, D. 2016. Pre-Season Fan Maintenance. Iowa State. Accessed November 2016. Available
online at:
http://www.extension.iastate.edu/dairyteam/sites/www.extension.iastate.edu/files/dairytea
m/Fan%20Maintenance.pdf. DCN DA00465A3.
Jacobsen, L. and J. Chastain. 1994. Fan performance and efficiency. University of Minnesota.
Available online at: http://www.extension.umn.edu/agriculture/manure-management-and-
air-quality/air-quality/fan-performance-and-efficiency-for-animal-ventilation-systems/.
DCN DA00465A2.
McManus, K.R., and P.L. Fan. 2003. Purchasing, Installing and Operating Dental Amalgam
Separators. Journal of the American Dental Association, 134:1054-1065. Document
Control Number (DCN) DA00162.
Shelton, D., and G. Bodman. 1995. G95-1244 Ventilation Fans: Efficiency and Maintenance.
University of Nebraska-Lincoln. Available online at:
http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1597&context=extensionhist.
DCN DA00465A1.
Stone, M.E. 2004. The Effect of Amalgam Separators on Mercury Loading to Wastewater
Treatment Plants. Journal of the California Dental Association, 32(7):593-600. DCN
DA00018.
U.S. Air Force. 2011. Synopsis of Dental Amalgam Separators. January 24. Dental Evaluation
and Consultation Service. DCN DA00079.
U.S. EPA. 2016. Municipal Solid Waste. Office of Land and Emergency Management.
Washington, DC. Available online at:
https://archive.epa.gov/epawaste/nonhaz/municipal/web/html/index.html. DCN
DA00496.
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Chapter 15—Implementation
Chapter 15
Implementation
This chapter provides guidance to dental dischargers and Control Authorities, such as
publicly owned treatment works (POTWs) in implementing the final rule.
15.1 Compliance Deadline
For existing sources, the compliance date, meaning the date that existing sources subject
to the rule must comply with the standards in this rule is three years after the effective date of the
final rule. Specifying a compliance date of three years from the effective date of the final
pretreatment standards rule is consistent with EPA's General Pretreatment Regulations, which
require existing sources to meet categorical pretreatment standards within three years of the
effective date of such standards, unless a shorter compliance time is specified therein. 40 CFR
403.6(b). After the effective date of the rule, new sources subject to this rule must comply
immediately with the standards in this rule. EPA reasonably established that for purposes of this
rule a new source is a dental discharger that first discharges to a POTW after the effective date of
the final rule. New sources have the opportunity to incorporate into their facilities the best
available demonstrated control technologies (unlike existing sources which have to retrofit) and
Congress envisioned that new sources would do so prior to beginning to discharge.
Table 15-1 presents the implementation deadline for existing and new sources of dental
dischargers.
Table 15-1. Compliance Deadline for Dental Offices Subject to the Final Rule
Dculiil Office
Ki'(|iiimiK'iil
Ik'iidliiK'
Existing Source
Comply with PSES
Three years after the effective date
New Source
Comply with PSNS
After the effective date of the rule,
immediately
15.2 Summary Of Dental Office Responsibilities
For dental offices that place or remove amalgam, the final rule requires installation,
operation, and maintenance of one or more amalgam separators (or its equivalent) that are
compliant with either the American National Standards Institute (ANSI) American National
Standard/American Dental Association (ADA) Specification 108 for Amalgam Separators
(2009) with Technical Addendum (2011) or the International Organization for Standardization
(ISO) 11143 Standard (2008) or subsequent versions so long as that version requires amalgam
separators to achieve at least a 95% removal efficiency. EPA does not expect dental offices to
demonstrate a separator is compliant with one of these standards. Rather, as shown in Table 9-1,
manufacturers obtain such demonstration for their amalgam separator models based on testing
results from a qualified laboratory and make this information readily available. In addition, the
ANSI and ISO standards require, among other things, marking of the amalgam separator (section
12 of the standard), and a test report (section 9 of the standard). Again, EPA expects the
manufacturer of the amalgam removal device, and not the dental office, to maintain such testing
reports and ensure the amalgam separator conforms to the marking requirements of the standard.
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Chapter 15—Implementation
The final rule allows dental offices to continue to operate existing amalgam separators for their
lifetime or ten years (whichever comes first), as long as the dental discharger complies with the
other rule requirements including the specified BMPs, operation and maintenance, reporting, and
recordkeeping requirements. Once the separator needs to be replaced or the ten-year period has
ended, dental offices will need to replace the amalgam separator with one that meets the
requirements of the final rule.
As an alternative to compliant amalgam separators, the rule provides that dental offices
may also install, operate, and maintain one or more amalgam removal devices other than an
amalgam separator (alternative device). Among other things, the rule requires that the alternative
device be tested to demonstrate removal efficiency. In the case of alternative devices, the dental
office must include information demonstrating that the alternative device meets the rule's design
requirements in their One-Time Compliance Report. EPA expects manufacturers of alternative
devices to provide such documentation to the dental office. Further details on the requirement of
the final rule are included in Chapter 8.3.
The pretreatment standards also specify certain operating and maintenance requirements
for the amalgam separator (or equivalent device). These include inspection in accordance with
the manufacturer's operating manual to ensure proper operation and maintenance of the
separator(s) and to confirm that all amalgam process wastewater is flowing through the amalgam
retaining portion of the amalgam separator(s); replacement of the amalgam retaining unit in
accordance with the manufacturer's operating manual or when the amalgam retaining unit has
reached the maximum level, whichever comes; and repair or replacement of the separator as
needed.
Solids collected by the amalgam separator may be a combination of dental amalgam,
biological material from patients, and any other solid material sent down the vacuum line. The
collected solids must be handled in accordance with federal, state and local requirements. To
facilitate compliance with state and local requirements several amalgam separator manufacturers
offer services that facilitate the transport of waste amalgam to facilities that separate mercury
from other metals in dental amalgam and recycle the mercury, keeping it out of the environment.
EPA recommends that dental dischargers take advantage of such services.
EPA is aware that some amalgam separator vendors (in addition to providing the needed
equipment) or service providers offer service contracts to maintain the system. For example, the
American Dental Association (ADA) established an affinity agreement with HealthFirst to offer
ADA members discounted amalgam separators and waste management services (ADA Business
Resources, 2014). These vendors also typically provide waste management services for the
collected solids. Some vendors also provide the necessary documentation and reports required by
existing state and local programs. EPA encourages but does not require dental offices to consider
such services, as they may aid compliance with the rule.
Lastly, dental offices must follow to BMPs. They must not discharge waste amalgam
(e.g., dental amalgam from chair-side traps, screens, vacuum pump filters, dental tools,
cuspidors, or collection devices. They also must not clean dental unit water lines, chair-side
traps, and vacuum lines that discharge amalgam process wastewater with oxidizing or acidic
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Chapter 15—Implementation
cleaners (e.g., bleach, chlorine, iodine and peroxide) that have a pH lower than 6 or greater than
8.
Reporting Requirements
Dental dischargers subject to the rule must comply with a one-time reporting requirement
specified in the final rule in lieu of the otherwise applicable reporting requirements in 40 CFR
403. Submission of reports as specified in the rule satisfies the reporting requirements in 40 CFR
403 and 40 CFR 441. For dental offices that do not place or remove dental amalgam except in
limited emergency or unplanned, unanticipated circumstances, dental offices must submit a One-
Time Compliance Report to their Control Authority that includes information on the dental
office and a certification statement that the dental discharger does not place dental amalgam and
does not remove amalgam except in limited emergency or unplanned, unanticipated
circumstances. For dental offices that place or remove dental amalgam, the One-Time
Compliance Report must include information on the dental office and its operations and a
certification that the dental discharger meets the requirements of the applicable performance
standard. Dental offices that utilize a third party to maintain their amalgam separator(s) must
report that information in their One-Time Compliance Report. Dental offices that do not utilize a
third party to maintain their amalgam separator(s) must provide a description of the practices
employed by the office to ensure proper operation and maintenance. EPA suggests dental offices
consider use of signs displayed prominently in the office or electronic calendar alerts to remind
staff of dates to perform and document inspections, amalgam-retaining unit replacement, etc.
If a dental practice changes ownership (which is a change in the responsible party, as
defined in 40 CFR 403.12(1)), the new owner must submit a One-Time Compliance Report that
contains the required information.
The One-Time Compliance Report must be signed by (1) a responsible corporate officer
if the dental office is a corporation; (2) a general partner or proprietor if the dental office is a
partnership or sole proprietorship; or (3) a duly authorized representative of the responsible
corporate officer, or general partner or proprietor. This does not preclude a third party from
submitting the report on behalf of a dental office as long as the submission also includes a proper
signature as described above. As long as a dental office subject to the final is in operation, or
until ownership is transferred, the dental office, or an agent or representative of the dental office,
must maintain the One-Time Compliance Report required at § 441.50(a) and make it available
for inspection in either physical or electronic form.
The final rule does not require electronic reporting nor does it prevent electronic
reporting. Still, EPA recognizes that some Control Authorities may prefer to receive the one-time
reports electronically or to provide affected dental dischargers with the option to report
electronically. EPA also recognizes that electronic submittal of required reports could increase
the usefulness of the reports, is in keeping with current trends in compliance reporting, and could
result in less burden on the regulated community and the Control Authorities. EPA may develop
and make available, via its E-Enterprise portal, an electronic reporting system that Control
Authorities could use to facilitate the receipt of reports from dental dischargers, if they choose to
do so.
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Chapter 15—Implementation
Recordkeeping Requirements
The final rule requires dental offices, or an agent or representative of the dental office, to
document certain operation and maintenance requirements and maintain all records of
compliance, as described in the regulation, and to make them available for inspection. The final
rule requires dental offices to document inspections, amalgam retaining unit replacement, that
collected dental amalgam is handled appropriately (preferably recycled), and any repair or
replacement of an amalgam separator or equivalent device. The dental office, or an agent or
representative of the dental office, must maintain these records and make available for inspection
in either physical or electronic form, for a minimum of three years. The dental office, or an agent
or representative of the dental office, should also maintain either a physical or electronic copy of
the manufacturer's operating manual for the current device.
15.3 Control Authority Oversight/Reporting
The final rule establishes for the purposes of Part 441, that dental dischargers are not
significant industrial users (SIUs) or categorical industrial users (CIUs) as defined in 40 CFR
403 unless designated as such by the Control Authority. By establishing that dental dischargers
are not SIUs or CIUs in the final rule, EPA eliminates the application of specific oversight and
reporting requirements in 40 CFR 403 such as permitting and annual inspections of dental
dischargers unless the Control Authority chooses to apply these requirements to dental offices.
This means that Control Authorities have discretion under the final rule to determine the
appropriate manner of oversight, compliance assistance, and enforcement.49 Further, the final
rule reduced reporting for dental offices (and associated oversight requirements by Control
Authorities) in comparison to reporting requirements for other industries subject to categorical
pretreatment standards, as it requires only a One-Time Compliance Report be submitted to the
Control Authority. The One-Time Compliance Report requirements specific to dental
dischargers are included in the final rule (40 CFR 441) rather than in the General Pretreatment
Regulations so that they may be implemented directly. In summary, for the final rule, the Control
Authorities must receive the One-Time Compliance Reports from dental dischargers and retain
that notification according to the standard records retention protocol contained in 403.12(o).
Where EPA is the Control Authority, EPA expects to explore compliance monitoring
approaches that support sector-wide compliance evaluations, to the extent practicable. States and
POTWs that are the Control Authority may elect to use the same approach but are not required to
do so. One approach may be periodic review and evaluation of nationwide data on releases of
dental amalgam metals (e.g., mercury), relying on Discharge Monitoring Reports from POTWs,
Annual Biosolids Reports from POTWs, emissions data from sludge incinerators, and
supplemental data submitted to EPA under the Toxic Releases Inventory program. EPA may
utilize an approach to compliance inspections that focuses on a statistically valid sample of the
regulated community. EPA may then use the inspection findings from such an approach to
identify common areas of noncompliance, which would inform decisions about needed outreach,
compliance assistance, and training materials. EPA will work with state and local Control
49 Nothing stated in this chapter shall be construed so as to limit EPA's inspection and enforcement authority.
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Chapter 15—Implementation
Authorities, the ADA and other partners to tailor oversight and outreach to the issues where such
oversight and outreach is most likely to achieve compliance across the dental sector.
15.4	Variances
The provision of this rule establishing that dental dischargers are not SIUs or CIUs unless
designated as such by the Control Authority does not change the otherwise applicable variances
and modifications provided by the statute. For example, EPA can develop pretreatment standards
different from the otherwise applicable requirements for an individual existing discharger subject
to categorical pretreatment standards if it is fundamentally different with respect to factors
considered in establishing the standards applicable to the individual discharger. Such a
modification is known as a "fundamentally different factors" (FDF) variance. See 40 CFR
403.13 and the preamble to the proposed rule (79 FR 63278-63279, October 22, 2014). FDF
variances traditionally have been available to industrial users subject to categorical pretreatment
standards. Whether or not a dental discharger is an SIU or CIU, it is subject to categorical
pretreatment standards and therefore eligible to apply for an FDF variance.
15.5	Phase-Out Of The Rule
Dental dischargers that do not remove amalgam except in limited emergency and
unplanned, unanticipated circumstances and that do not place dental amalgam can certify such in
their One-Time Compliance Report submitted to the Control Authority. To clarify, the limited
circumstances50 provision applies to the removal, but not the placement of dental amalgam. A
dental office that stocks amalgam capsules clearly intends to place amalgam, and does not
represent the type of limited circumstances this provision is intended to address. Further, in
EPA's view, dental offices that remove amalgam at a frequency more than five percent of its
procedures are not likely engaging in limited, unplanned removals. EPA estimates that on
average, a single chair dental office would remove amalgam 183 times per year (DCN
DA00467). An amalgam removal rate that represents less than five percent of this frequency
consists of approximately nine removals per year, on average, respectively. However, because
EPA does not have, nor did commenters provide, data on the frequency of such unplanned and
unanticipated instances nationwide, the final rule does not include a specific definition of limited
circumstances. Rather, EPA expects a dental office to carefully consider its operation in light of
the information provided above and only certify accordingly to their Control Authority if it meets
the situation EPA described.
The final rule does not expire on a particular date. However, as use of dental amalgam as
a treatment for dental cavities decreases, removals will eventually decrease as well, and dentists
can ultimately certify that do not place amalgam and only remove dental amalgam in limited
emergency or unplanned, unanticipated circumstances. This essentially creates an "off-ramp" for
dental dischargers once dental amalgam placements and removals discontinue. A dental
discharger that installs a separator and certifies its operation meets the requirements of the
applicable performance standard in its One-Time Compliance Report that later changes it
operation such that it no longer places dental amalgam, and does not remove amalgam except in
50 As it has done here, EPA sometimes shortens "limited emergency and unplanned, unanticipated circumstances" to
"limited circumstances." For purposes of this final rule, these terms are synonymous.
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Chapter 15—Implementation
limited emergency and unplanned, unanticipated circumstances, may also elect to comply with
this rule at that time via this provision. While the rule does not require such offices to submit a
second One-Time Compliance Report, EPA recommends the office do so. At a minimum, EPA
suggests the office prepare and sign a certification and retain it along with the original One-Time
Compliance Report.
Also, section 307(b) requires EPA to revise its pretreatment standards for indirect
dischargers "from time to time, as control technology, processes, operating methods, or other
alternatives change." See CWA section 307(b)(2). Section 304(g) requires EPA to annually
review these pretreatment standards and revise them "if appropriate." Although section 307(b)
only requires EPA to revise existing pretreatment standards "from time to time," section 304(g)
requires an annual review. Therefore, EPA meets its 304(g) and 307(b) requirements by
reviewing all industrial categories subject to existing categorical pretreatment standards on an
annual basis to identify potential candidates for revision.
15.6 References
ADA Business Resources. 2014. HealthFirst Amalgam Recovery Program. Accessed 2014. DCN
DA00246.
ANSI/ADA. 2009. Specification 108 for Amalgam Separators (2009). February. DCNDA00514.
ANSI/ADA. 2011. Specification 108 for Amalgam Separators (2009) with Technical Addendum
(2011). January. DCNDA00515.
ISO. 2008. International Organization for Standardization. ISO 11143:2008 Dentistry -
Amalgam Separators Standard. July. DCNDA00138.
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Chapter 16—Quality Assurance Activities for the Dental Category Costing and Loading Analyses
Chapter 16
Quality Assurance Activities for the Dental Category Costing
and Loading Analyses	
The ELGs for the Dental Category are based on data generated or obtained in accordance
with EPA's Quality Policy and Information Quality Guidelines. EPA's quality assurance (QA)
and quality control (QC) activities for this rulemaking include developing, approving, and
implementing Quality Assurance Project Plans for the use of environmental data generated or
collected from sampling and analyses, existing databases, literature searches, and for developing
any models that used environmental data.
For the costing and loading analyses, EPA only used secondary data (i.e., data not
collected to specifically support the dental category rulemaking). EPA used secondary data to
calculate compliance costs for dental offices to purchase and install treatment technologies (i.e.,
amalgam separators) to reduce mercury and other metal discharges to publicly owned treatment
works (POTWs). EPA also used secondary data to calculate baseline and post-compliance
pollutant loadings of mercury and other metals from dental offices to publicly owned treatment
works (POTWs) and subsequently to waters of the United States.
EPA acknowledges that data provided in references include a certain level of uncertainty.
To address this uncertainty, EPA completed sensitivity analyses for the compliance costs (see
Chapter 16.4). Uncertainties may exist due to currency of the information (e.g., costs from a
2011 publication), limited number of data points (e.g., only two examples of installation costs for
dental offices with 1 or 2 chairs), and other assumptions (e.g. use of average amalgam separator
purchase, installation, replacement part, and recycling costs based on model dental offices).
This chapter presents the following:
•	Cost drivers;
•	Costs uncertainty;
•	Loadings analyses uncertainties; and
•	Alternative POTW mercury removal analysis.
16.1 Cost Drivers and Uncertainty with Compliance Costs
Costs may differ among dental offices. For example, amalgam separator costs may be
less expensive for smaller sized dental offices (defined by the number of chairs) than for large
dental offices or institutional facilities. Costs also vary by locality, dental office location, as well
as each individual dental office's selected amalgam separator or other amalgam collecting
device. Where available, EPA collected cost information that is based on dental office size (i.e.,
number of chairs) so that costs can be evaluated for a range of dental office sizes.
As detailed in Chapter 9, compliance costs for dental offices include one-time and annual
costs. One-time costs include amalgam separator purchase cost, separator installation cost, and
reporting costs (i.e., baseline compliance report). Annual costs include the following:
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Chapter 16—Quality Assurance Activities for the Dental Category Costing and Loading Analyses
•	Replacement of the amalgam-retaining unit (e.g., canister, cartridge, or filter);
•	Amalgam separator inspection costs (assumed to incur monthly to represent rule
requirement for inspection based on manufacturer's user manual);
•	Separator maintenance/cleaning costs (assumed to incur biweekly to represent rule
based on manufacturer's user manual);
•	Oversight of amalgam separator repairs;
•	Amalgam recycling preparation (assumed to incur twice per year to represent rule
requirement based on manufacturer's user manual); and
•	Annual amalgam recycling costs.
Factors that can influence the incremental compliance costs for a dental office include the
number of amalgam placements and removals, volume of wastewater generated (e.g., use of wet
or dry vacuum system), and number of chairs. EPA used model dental offices based on practice
size and average costs for each model dental office to calculate the incremental compliance costs
for dental offices to comply with the final rule (see Chapter 9). Actual costs to a specific dental
office may be higher or lower depending on location, choice of control device, and office
configuration.
As EPA compiled costing data, it found a wide range in amalgam separator design,
including ease of use, technology used (e.g., filtration, sedimentation, ion exchange), efficiency,
frequency and need for replacement parts, and types of services included in the cost (e.g.,
recycling). This resulted in a wide range of costs for purchasing amalgam separators and
replacement part costs that exceeded the ±25 percent used for the quality assurance analysis.51
Rather than arbitrarily selecting certain amalgam separators with similar costs (±25 percent),
EPA captured a wide range of data points to estimate average incremental compliance costs for
dental offices.
Amalgam separator purchase costs have a high variability due to a wide range in costs
between different manufacturers, even after grouping costs by chair size. The largest range of
amalgam separator costs were for dental offices with 3 to 5 chairs (approximately $325 to
$1500). For the smallest dental office size (1 or 2 chairs), purchase costs ranged from $230 to
$815. Amalgam separator costs for the 6-chair and 7 to 14-chair size groups were less variable
(see Table 16-2). For large institutional offices (15 chairs), variability in costs ($1,510 to $4,510)
may be partially due to the wide range in number of chairs at these facilities (i.e., can exceed 25
chairs). Because the amalgam separator costs increased with increasing size of the dental office,
using the average provides a reasonable cost estimate.
Amalgam separator replacement part costs also have a high variability due to a wide
range in costs between different manufacturers, even after grouping costs by chair size. In some
cases, manufacturers recommend replacing the entire system which can be a higher cost than
changing out a container or filter. The largest range of replacement part costs were for dental
offices with 7 to 14 chairs (approximately $210 to $1500). For the smallest dental office size (1
51 In the Amalgam Separator Cost Spreadsheet (U.S. EPA, 2016a), EPA compared each data point used in the
analysis to the calculated average that EPA used to determine compliance costs for dental offices as a result of the
final rule.
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Chapter 16—Quality Assurance Activities for the Dental Category Costing and Loading Analyses
or 2 chairs), replacement part costs ranged from $160 to $650. Replacement part costs for the 3
to 5 chair and 6-chair size groups were closer in range, but costs could still be three times higher
for one amalgam separator compared to another. Because the annual replacement part costs
increased with increasing size of the dental office, using the average provides a reasonable cost
estimate.
Installation costs also varied within each model dental office size group. This may be due
to the location, layout, or plumbing configuration of the dental office. Because installation costs
increased with increasing size of the dental office, using the average is reasonable even though
there is variability in each model dental office size group (U.S. EPA, 2016b).52
16.2 Development of Cost Calculation Spreadsheets
EPA developed several spreadsheets to estimate costs for dental offices to meet the
Dental Category pretreatment standards, including requirements for BMPs, amalgam separators,
maintenance of separators, and compliance reporting. EPA also developed a spreadsheet to
estimate costs (burden) to Control Authorities that will receive baseline compliance reports and
transfer of ownership forms from dental offices.
EPA revised the spreadsheet used at proposal to calculate amalgam separator costs
(purchase cost, replacement parts cost, and recycling cost) by chair size. EPA performed the
following steps to update the proposal costs:
1.	Reviewed the amalgam separators used in the costing calculations to ensure they meet
ISO 11143 (2008) / ANSI requirements. EPA removed those separators that do not
meet the ISO standard (NH, 2015; USAF, 2011).53 In addition, units no longer offered
by manufacturers were also removed from the costing analysis54 (Rebec
Environmental, 2016; R&D Services, 2016; AB Dental Trends, 2016). EPA did not
add any additional amalgam separators to the cost spreadsheet.
2.	Revised costs based on 2016 data, either by identifying current online costs or
converting costs to 2016 dollars. EPA converted costs to $2016 using RSMeans®
Historical Cost Indexes, using the following equation:
Index 2016
$2016 = %Year x , ^
IndeXyear
52	In the Amalgam Separator Installation Cost Spreadsheet (U.S. EPA, 2016b), EPA compared each data point used
in the analysis to the calculated average that EPA used to determine compliance costs for dental offices as a result of
the final rule.
53	New Hampshire's 2015 list of amalgam separators meeting the ISO 11143 standard for solids removal includes
two units from Maximum Separation Systems (MSS 1000 and MS 2000) (NH, 2015). EPA did not find information
on the MS 601 unit, and therefore, excluded it from the amalgam separator cost analysis.
54	Proposal costs included six amalgam separators from Rebec Environmental. The website only lists three amalgam
separator units (CATCHHG 400, CATCHHG 1000, and Custom Systems). Proposal costs included two 400 series
units, two 1000 series units, and two 6000 series units (custom systems). For final costs, EPA combined the costing
information to develop a range of purchase, replacement parts, and recycling prices to represent each series (i.e., 3
units total from Rebec Environmental).
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Chapter 16—Quality Assurance Activities for the Dental Category Costing and Loading Analyses
3. For the calculation of annual replacement part costs, EPA assumed that the canister
(or other container), filter, and cartridge replacements would occur no less frequently
than annually. For annual replacement parts cost (minimum and maximum), there are
five scenarios where calculations occur (i.e., not a direct transfer of cost from the
referencex), listed below.
i.	If the manufacturer recommends exchanging the canister (or other container),
filter, or cartridge more than every 12 months, EPA used the value replacement
cost to represent the annual cost (i.e., assume the dental office will replace the
part every year to comply with the dental category rulemaking). This value
represents both the minimum and maximum cost for replacement parts each year
for that amalgam separator.
ii.	If the manufacturer recommends exchanging the canister (or other container),
filter, or cartridge less than every 12 months, EPA used the replacement cost to
estimate the annualized cost to represent both the minimum and maximum annual
cost. For example, if a manufacturer recommends replacing the filter every nine
months, EPA calculated an annual cost using the following equation:
12 months
Annual Cost = Replacement Cost x —	-—
9 months
iii. If the manufacturer lists a range of time when the canister (or other container),
filter, or cartridge needs to be exchanged, EPA calculated a minimum and
maximum annual cost, with the maximum no less than every 12 months. For
example, a manufacturer recommends replacing the filter every 6 to 12 months,
EPA calculated annual replacement parts costs using the following equations:
12 months
(Annual Cost)min = Replacement Cost x —	—
12 months
12 months
(Annual Cost)max = Replacement Cost x		—
6 months
iv.	If the manufacturer recommends replacing the canister (or other container), filter,
or cartridge every 6 to 18 months, the replacement costs would be the same as (c)
listed above (i.e., 12-month maximum).
v.	For American Dental Accessories AD-1000 and Rasch AD-1500, filter changes
occur every 18 months per dentist (MCES, 2009). These units are included in the
7+ chair size category, with a range of 7 to 12 chairs. EPA assumed there are 2 to
4 dentists working in a dental office with 7 to 12 chairs. This is based on the
Safety Net Dental Clinic Manual recommendation of 3.0 operatories per dentist
(National Maternal & Child Oral Health Resource Center, 2011).
The calculation of the replacement part costs would then be:
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Chapter 16—Quality Assurance Activities for the Dental Category Costing and Loading Analyses
12 months
(Annual Cost)min = Replacement Cost x
18 months
x2 dentists
12 months
(Annual Cost)max = Replacement Cost x
18 months
x4 dentists
EPA revised the spreadsheet used at proposal to calculate incremental compliance the
costs as calculated by chair size. The revisions included:
1.	Removed the reporting burden estimate to complete a 90-day compliance form and
annual compliance forms. Added a burden estimate (time) for dental offices to
complete annual transfer of ownership forms. EPA assumed 10 percent of dental
offices will submit a transfer of ownership form annually.
2.	Revised number of dental offices by chair size used in the calculation sheet to reflect
2012 Economic Census numbers.
3.	Revised installation costs included as inputs for the costing calculations based on
comments received (used multiple study references).
4.	Included cost offset for dental offices without technology in place based on a
comment received on the proposed rule. See DCN DA00490 and DA00491.
5.	Added the following annual (recurring costs): visual inspection recordkeeping,
separator maintenance (e.g., replacement of amalgam retaining canister, cartridge or
filter) recordkeeping, separator repair/recordkeeping, and recycling recordkeeping.
16.3 Activities for the Dental Category Loading Analysis
As described in Chapter 11, EPA calculated mercury and other metal loadings55 from
dental offices to POTWs and from POTWs to surface water on an industry-wide basis. Specific
pollutant loadings from dental offices will vary based on the size of the dental practice, number
of dental amalgam placements (or restorations) and removals performed at the office, and current
treatment technology in place. EPA estimated baseline pollutant loadings and loading removals
(or reductions) as a result of the final rule.
For baseline pollutant loadings, EPA accounted for current treatment technology in place
at dental offices, including chair-side traps, vacuum system filters, and amalgam separators. For
post-compliance pollutant removals, EPA assumed all dental offices would operate chair-side
traps, vacuum filters, and amalgam separators with a median percent removal of 99.3 percent
(U.S. EPA, 2016a; U.S. EPA, 2016c). To estimate discharges to surface water, EPA accounted
for pollutant removal at the POTW by secondary treatment technologies.
EPA used different types of references for the loadings analysis including publications in
a peer reviewed journal; government publications; industry, trade association, or vendor
information; and other references (e.g. figure from a state website showing composition of dental
55 Other metals include silver, tin, copper, and zinc.
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Chapter 16—Quality Assurance Activities for the Dental Category Costing and Loading Analyses
amalgam). For each reference, EPA evaluated whether the data provided were current, complete,
accurate, and reasonable. EPA also evaluated the uncertainty for each of the references.
Data from a publication in a peer reviewed journal are considered complete, accurate, and
reasonable if the source is clearly written, documents any methodologies or assumptions, and
where relevant, describes variability and uncertainty. The primary reference that EPA used for
the loadings analysis is a 2005 publication from a peer reviewed journal: "An Assessment of
Mercury in the Form of Amalgam in Dental Wastewater in the United States" by Jay Vandeven
and Steve McGinnis, published in Water, Air, and Soil Pollution (Vandeven & McGinnis, 2005).
EPA reviewed the data source and confirmed that the publication presented the methodology,
assumption, and data sources, was relevant to the dental industry, and where relevant, described
the variability and uncertainty. The loadings analysis input data used from this reference include
the following:
•	71,000,000 total restorations (placements) performed in the U.S. each year, as
estimated by ADA in 1999. As noted in Vandeven and McGinnis, 2005, this number
of total restorations correlated well with more recent estimates of mercury use in
dentistry conducted by the U.S. Geological Society (USGS) in 2000. EPA received
comments that the number of amalgam placements is declining in the U.S due to
alternative filling materials and better dental health. Although EPA continued to use
the number of total placements reported in this publication (71,000,000) for its
loadings analysis, EPA conducted a sensitivity analysis to determine this factor's
impact on the loadings analysis (see Chapter 16.5).
•	450 milligrams (mg) of mercury in amalgam capsules based on another peer reviewed
journal.
•	340 mg of mercury used for an amalgam placement (75 percent of capsule). As
reported in Vandeven and McGinnis, approximately 25 percent of the amalgam
triturated by dentists is collected and recycled or disposed of as non-contact waste
amalgam. The authors identified three references that placed the range between 15
and 50 percent and noted that the 25 percent is only an approximate value based on a
government publication (Barron, T. 2001 .Mercury Headworks Analysis for 2000.
Palo Alto Regional Water Quality Control Plant).
•	9 percent of the mercury used for an amalgam placement (or 30.6 mg) enters the
dental office wastewater. This estimate is based on a government publication (Barron,
T. 2001. Mercury Headworks Analysis for 2000. Palo Alto Regional Water Quality
Control Plant).
•	710 amalgam removals per year per general dentist. This estimate is based on
normalized data from five municipal studies (i.e., government publications). EPA
acknowledges that this estimate is based on older studies; however, EPA did not
identify any more recent data to use in the loadings analysis. Because this is an
uncertainty in the analysis, especially since the number of dentists between the
proposed rule and final rule increased, EPA conducted a sensitivity analysis to
determine this factor's impact on the loadings analysis (see Chapter 16.5).
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Chapter 16—Quality Assurance Activities for the Dental Category Costing and Loading Analyses
•	440 amalgam removals per year per specialist. The authors did not have available
data regarding the removal rate of amalgam at specialty offices. Therefore, the
analysis assumes the rate of amalgam removal for specialists is similar to the rate of
placements by specialists. As noted above, the number of removals per year at dental
offices is an estimate with an elevated level of uncertainty and EPA performed a
sensitivity analysis on this factor for the loadings calculation (see Chapter 16.5).
•	300 mg of mercury extracted from a patient's mouth during amalgam removal, which
accounts for mercury loss during normal wear for the life of the filling. The estimate
is based on two references, a publication in a peer reviewed journal and an industry
study. The studies estimated 280 mg and 320 mg of mercury will be extracted at
removal. The authors used the average mercury amount, resulting in a variability of
±7 percent.
•	90 percent of the amalgam filling removed mercury enters the dental office
wastewater (270 mg). This estimate is based on a government publication (Barron, T.
2001. Mercury Headworks Analysis for 2000. Palo Alto Regional Water Quality
Control Plant).
•	Amalgam removal efficiency of chair-side traps of 68 percent, which is the average of
two studies (both publications in peer review journals); one study determined a
capture efficiency of 60 percent and the other, a capture efficiency of 75 percent.
Therefore, the variability in the removal efficiency for chair-side traps can be as high
as ±12 percent.56 In addition, Vandeven and McGinnis note that the capture efficiency
assumes that dentists properly maintain the chair-side traps.
•	EPA used the estimated industry-wide amalgam removal efficiency of 78 percent to
represent the capture efficiency of a chair-side trap and vacuum filter. The capture
efficiency from properly maintained chair-side traps and vacuum filters was identified
in the literature as 81 percent. Depending on the specific dental office and whether
the technologies are properly maintained, there is a range of uncertainty in the amount
of amalgam currently captured at these dental offices. EPA performed a sensitivity
analysis on the treatment efficiency of chair-side traps and vacuum filters to
determine the factors' impact on the loadings calculations (see Chapter 16.5).
•	20 percent of dental offices operate chair-side traps only. Vandeven and McGinnis
reported that 80 percent of dental offices operate both chair-side traps and vacuum
filters in their 2005 study. To determine the number of dental offices with treatment
technology in place, EPA assumed 20 percent of offices operate chair-side traps only,
and the remaining 80 percent of offices operate chair side traps and vacuum filters.57
EPA also used information from another publication from a peer reviewed journal, "The
Effect of Amalgam Separators on Mercury Loading to Wastewater Treatment Plants" by M.E.
Stone, published in the 2004 Journal of the California Dental Association, 3 2(7): 5 93-600. As
56	The range of capture efficiencies of chair-side traps has a variability of -12 percent to +10 percent.
57	These dental offices may also use amalgam separators to control amalgam discharges.
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Chapter 16—Quality Assurance Activities for the Dental Category Costing and Loading Analyses
discussed in the publication, mercury in wastewater from dental chairs contains primarily
elemental mercury bound to amalgam particulate. Mercury is also present in the wastewater as
ionic mercury (Hg+2) and two forms of dissolved mercury, elemental mercury (Hg°) and
monomethyl mercury (MeHg). Six samples in the study present the concentration of each form
of mercury in the dental wastewater. The portion of mercury bound to the amalgam particulate
ranged from dissolved concentration ranges from 94.88 to 99.87 percent of the total mercury. For
the loadings analysis, EPA assumed the amount of dissolved mercury in the wastewater is
negligible. To determine the impact that the concentration of dissolved mercury can have on the
pollutant loadings passing through the dental office control technologies, EPA conducted a
sensitivity analysis (see Chapter 16.5).
Data from government publications are assumed to be complete, accurate, and reliable.
The Vandeven and McGinnis, 2005 reference used data from government publications as
described above. EPA also used government publications to determine the pollutant removal
efficiencies at POTWs. In addition to the loadings analysis, EPA also used these values to
determine whether the pollutants pass through POTWs (see Chapter 11). EPA confirmed that the
data used are relevant to wastewater from the dental industry being treated at municipal
treatment plants.
EPA also used trade association (ADA) data, Supply of Dentists in the U.S. 2001 - 2015,
to determine the number of dentists and dental offices and type of practice (general or specialty).
Using these data, EPA estimated the number of dentists and dental offices that may place or
remove amalgam (U.S. EPA, 2016c). Although trade association data are less certain than peer-
reviewed data, EPA determined that information from ADA are accurate and reliable. EPA
evaluated the data for completeness and relevancy to the loadings analysis.
Other information obtained from non-industry, non-peer reviewed sources such as news
sites and other websites are less certain than other sources, however, can be useful for general
information or on a supplemental basis for the loadings analysis. EPA used a figure available on
the Massachusetts Water Resources Authority website that shows the amalgam composition in
typical dental fillings. After calculating mercury loadings, EPA used the percentages presented in
the figure (49 percent mercury, 35 percent silver, 9 percent tin, 6 percent copper, and 1 percent
zinc) to estimate non-mercury metal loadings. EPA evaluated data from this other source for
relevancy when used in the loadings analysis.
EPA used multiple types of references to determine the amalgam capture efficiency of
separators, including peer reviewed journal publications, government sources, industry sources,
and communication with vendors. The capture efficiency for amalgam separators that meet the
2008 ISO 11143 / ANSI standard ranges between 95 and 99.96 percent. EPA used the median
value of 99.3 percent. By definition of median, the actual removal efficiency at any given dental
office will be higher in half of dental-offices, and lower in half of dental-offices. The median
performance is based on lab studies conducted at extreme conditions: the testing is done at
maximum water flow rates and under conditions of both empty and full. The performance of the
separator when not operating under these extreme conditions is likely to be better.
EPA's loadings analysis evaluated nationwide discharges of mercury and other metals to
POTWs. Loadings at individual dental offices and POTWs will vary by a number of factors,
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Chapter 16—Quality Assurance Activities for the Dental Category Costing and Loading Analyses
such as number of placements and removals and control technology currently in place. EPA
acknowledges that data provided in references used for the loadings analysis include a certain
level of variability and uncertainty. Variability and uncertainties may exist due to currency of the
information (e.g., use of data from a 2005 publication), limited number of data points (e.g.,
amalgam separator efficiency based on certification test but may vary at a dental office), and
other assumptions (e.g., amalgam removal efficiency for equipment - chair-side trap, vacuum
filter, and amalgam separator are based on well-operated systems). The pollutant loadings that
EPA presents in Chapter 11 and the corresponding cost effectiveness evaluation presented in
Chapter 12 reflect the use of these data. Because the loadings to POTWs and surface water can
vary based on a number of factors, EPA performed sensitivity analyses to determine how
individual input data may affect the estimated baseline and post-compliance mercury loadings.
EPA expects similar impacts apply to other metal loadings included in the analysis (silver,
copper, tin, and zinc).
16.3.1 Development of Loadings Calculations
EPA developed several worksheets to estimate baseline and post compliance mercury and
other metal loadings from dental offices. EPA used the most recent ADA data available on the
number of dentists and dental offices (ADA, 2016). EPA also used the ADA data to revise the
percent of specialty dental offices that may place or remove amalgam (see Chapter 10). Based on
the revised amalgam separator models in the costing analysis, EPA calculated the median percent
efficiency for amalgam separators that meet the 2008 ISO 11143 standard to be 99.3 percent
(U.S. EPA, 2016a). EPA also revised the POTW percent removal for mercury to be three
significant digits rather than two significant digits (90.2 percent rather than 90 percent).
16.4 Sensitivity Analysis for Costs
EPA used average costs for model dental offices to calculate one-time and annual
compliance costs for dental offices that must comply with the dental category final rule. The
incremental compliance costs that EPA presents in Chapter 9 and corresponding economic
impacts presented in Chapter 10 reflect the use of these average model dental office costs. Table
16-1 provides component level costs based on the proposed rule cost components. Costs were
calculated using both the Colorado Survey and the ADA survey, to show the costs are similar
using both data sets. The contribution of the cost as a percent of the total cost is displayed below
the cost.
Table 16-1. Dental Industry Cost Breakout by Component (Millions; 2016$)
Cost Category
Colorado Survey
ADA Survey
Equipment, installation, and year 10 replacement
$10.2
(16 percent)
$10.5
(16 percent)
O&M
$47.0
(72 percent)
$48.2
(72 percent)
Inspections by dental office, recordkeeping, reporting
$8.4
(13 percent)
$8.4
(13 percent)
Total
$65.5
$67.1
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Chapter 16—Quality Assurance Activities for the Dental Category Costing and Loading Analyses
Because the costs to individual dental offices can vary, EPA performed sensitivity
analyses to determine how individual cost elements may affect the estimated incremental
compliance costs to dental offices for the final rule. This subsection includes a summary of the
cost elements that can impact the incremental compliance costs due to their variability. EPA
performed sensitivity analyses on the following cost elements: amalgam separator costs, annual
replacement part costs, and annual maintenance costs.
16.4.1 Sensitivity Analysis for Amalgam Separator Purchase Costs
As a first step in conducting the sensitivity analysis, EPA compared the average amalgam
separator purchase cost (used for final rule), least expensive retail price (lower-bound cost), and
most expensive retail price (upper-bound cost) within each model dental office size (U.S. EPA,
2016a). As noted in, the largest range of amalgam separator purchase costs were for dental
offices with 3 to 5 chairs. Table 16-2 presents the range of costs for individual amalgam
separator models (lower and upper bound retail price) for each model dental office size group.
Table 16-2. Range of Amalgam Separator Purchase Costs ($2016) by Model Dental
Office
Model Dental
Office
(Chair Size)
Number of
Data Points
Amalgam Separator Purchase Cost ($2016)
Average"
Lower-Bound Retail Price
(Percent Difference from
Average)
Upper-Bound Retail Price
(Percent Difference from
Average)
1 or 2 Chairs
6
$437
$228 (-48%)
$813 (+86%)
3, 4, or 5 Chairs
5
$697
$325 (-53%)
$1,479 (+112%)
6 Chairs
3
$1,058
$895 (-15%)
$1,320 (+25%)
7 to 14 Chairs
10
$1,291
$731 (-43%)
$2,177 (+69%)
15 Chairs
6
$2,424
$1,512 (-38%)
$4,510 (+86%)
Source: U.S. EPA, 2016a; U.S. EPA, 2016e.
a - EPA used this purchase cost to calculate incremental compliance costs for dental offices.
For the 3,4, or 5-chair office size groups, the upper-bound amalgam separator costs are
more than double the average cost (i.e., more than 100 percent). The 6-chair size group had the
least variability in cost; this is most likely due to the small number of data points (three). As
noted earlier, EPA did not want to arbitrarily select certain amalgam separators for its analysis
solely due to similar costs. Instead, EPA captured a wide range of data points to represent the
range of amalgam separators on the market. After calculating the average purchase price for each
size category, EPA determined that the cost trend is reasonable (i.e., costs for dental offices with
more chairs are greater than costs for dental offices with less chairs). EPA acknowledges that the
purchase cost incurred by an individual dental office may be higher or lower than the average
used in its analysis. On a nation-wide basis, EPA determined that the use of the average purchase
price provided a reasonable estimation of the costs incurred by dental offices. Because EPA
expects dentists will select an appropriate separator model for their particular office, and because
EPA has identified at least 26 amalgam separators that could be used by dentists to meet rule
requirements, the use of average costs most likely overstates the average costs per dentist of the
rule.
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Chapter 16—Quality Assurance Activities for the Dental Category Costing and Loading Analyses
EPA commonly evaluates one-time (or capital) costs on an annualized basis to determine
the economic achievability of regulatory options. EPA compared the annualized costs for the
range of amalgam separator purchase costs within each model dental office size group. EPA
annualized costs across a 10-year basis58 for the average amalgam separator purchase cost,
lower-bound retail price, and upper-bound retail price for each model dental office size group.
Table 16-3 presents the costs annualized across 10-years.
Table 16-3. Annualized Amalgam Separator Purchase Costs ($2016) by Model Dental
Office
Model Dental
Office (Chair Size)
10-Year Annualized Amalgam Separator Purchase Cost ($2016)
Average
Lower-Bound Retail Price
Upper-Bound Retail Price
1 or 2 Chairs
$44
$23
$81
3, 4, or 5 Chairs
$70
$33
$148
6 Chairs
$106
$90
$132
7 to 14 Chairs
$129
$73
$218
15 Chairs
$242
$151
$451
Source: U.S. EPA, 2016e.
Looking at the conservative, upper-bound estimate of amalgam separator purchase costs,
the final rule would cost dental offices between $81 and $451 per year, depending on the size of
the dental office. As noted earlier, some dental offices may purchase amalgam separators that
cost more or less than the average purchase cost used in the economic analysis for the final rule.
EPA found that the annualized cost to purchase an amalgam separator accounting for the upper-
bound of the purchase price range is affordable.
The capital costs are annualized over 10 years, assuming a 7 percent discount rate these
costs, thus approximately 13.9 percent of the capital cost is incurred per year. Thus a 10 percent
increase in capital costs would result in less than a two percent increase in annual costs. As
presented above, equipment and installation costs are 16 percent of the total costs to dentists. A
two percent increase in annual costs results in no significant change in total costs. EPA
concludes that capital costs and installation is not a driver of total rule costs.
16.4.2 Sensitivity Analysis for Amalgam Separator Replacement Part Costs
EPA calculated annual costs for model dental offices to replace the amalgam-retaining
unit of the amalgam separator using two factors 1) retail price of the replacement part (in 2016
dollars) and 2) manufacturer's recommended replacement frequency. The recommend
replacement frequency can be a range (e.g., 6 to 8 months) or specific time (e.g., every 12
months.). For each amalgam separator, EPA calculated a minimum and maximum annual cost
based on the frequency of replacing the part. EPA assumed a maximum frequency of 12 months
for replacing the amalgam-retaining unit (U.S. EPA, 2016a). Replacement parts include filters,
cartridges, canisters, and collection containers. For a few models, the amalgam-retaining unit is
reusable and therefore, the minimum annual cost for replacement parts is $0. Dental offices using
58 EPA assumed a 10-year life for amalgam separators in its economic analysis (see Chapter 10).
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Chapter 16—Quality Assurance Activities for the Dental Category Costing and Loading Analyses
separators with reusable containers would only incur costs to recycle or dispose of the retained
amalgam. In addition, some models require the replacement of the entire amalgam separator.
EPA compared the range of annual amalgam separator replacement part costs, accounting
for retail price and frequency of replacement, within each model dental office size (U.S. EPA,
2016a). Table 16-4 presents the average replacement part costs (used for final rule), lowest
annual replacement part cost (lower-bound cost), and highest annual replacement part cost
(upper bound cost) for each model dental office size group.
Table 16-4. Range of Annual Replacement Part Costs ($2016) by Model Dental Office
Model Dental
Office (Chair
Size)
Number of
Data Points
Annual Replacement Part Cost ($2016)
Average3
Lower-Bound Annual
Cost (Percent Difference
from Average)
Upper-Bound Annual Cost
(Percent Difference from
Average)
1 or 2 Chairs
6
$275
$0 (-100%)b
$648 (+135%)
3, 4, or 5 Chairs
5
$386
$223 (-42%)
$699 (+81%)
6 Chairs
3
$559
$0 (-100%)b
$1,083 (+94%)°
7 to 14 Chairs
10
$732
$0 (-100%)b
$1,522 (+108%)
15 Chairs
6
$1,078
$518 (-52%)
$1,679 (+56%)
Source: U.S. EPA, 2016a; U.S. EPA, 2016e.
a - EPA used this annual cost to calculate incremental compliance costs for dental offices,
b - One amalgam separator in this model dental office size category offers reusable replacement parts (i.e., annual
costs equal $0).
c - Upper-bound annual cost based on replacing entire amalgam separator.
The upper-bound annual replacement costs are more than double the average costs for
two model dental office size groups: 1 to 2 chairs (+135 percent) and 7 to 14 chairs (+108
percent). This range in annual costs does indicate some variability in the annual costs that may
be incurred by dental offices to comply with the final rule. As with the purchase costs, EPA did
not want to arbitrarily select certain amalgam separators for its costing analysis solely due to
similar costs. Instead, EPA captured a wide range of data points for the range of amalgam
separators on the market. EPA used the average annual cost by model dental office as a best
representation of the replacement parts costs for dental offices nationwide. After calculating the
average annual replacement part costs for each size category, EPA determined that the cost trend
is reasonable (i.e., annual costs for dental offices with more chairs are greater than annual costs
for dental offices with less chairs). EPA acknowledges that the annual replacement part cost
incurred by an individual dental office may be higher or lower than the average used in its
analysis.
EPA determined the impact that the range of replacement part costs has on the total
annual costs incurred by dental offices. Table 16-5 presents the total annual costs for dental
offices based on the average replacement part cost, lower-bound replacement part cost, and
upper-bound replacement part cost for each model dental office size group. The table includes
the following:
• Average: total annual cost for dental offices to comply with the final rule using the
average replacement part costs presented in Table 16-4. For example, the total annual
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Chapter 16—Quality Assurance Activities for the Dental Category Costing and Loading Analyses
costs for the 1 or 2 chair size group includes the $275 replacement part cost plus
visual inspection costs, amalgam recycling costs, etc.
•	Lower-bound: total annual cost for dental offices to comply with the final rule using
the lower-bound replacement part costs presented in Table 16-4. For example, the
total annual costs for the 1 or 2 chair size group includes the $0 replacement part cost
plus visual inspection costs, amalgam recycling costs, etc.
•	Upper-bound: total annual cost for dental offices to comply with the final rule using
the upper-bound replacement part costs presented in Table 16-4. For example, the
total annual costs for the 1 or 2 chair size group includes the $648 replacement part
cost plus visual inspection costs, amalgam recycling costs, etc.
Table 16-5 also presents the percent difference in the total annual costs for dental offices
based on the range of replacement part costs.
Table 16-5. Total Annual Incremental Compliance Costs Based on the Range of
Replacement Part Costs by Model Dental Office
Model Dental Office
(Chair Size)
Annual Incremental Compliance Costs ($2016)
Average Used for
Final Rule
Based on Lower-Bound
Replacement Part Cost
(Percent Difference from
Average)
Based on Upper-Bound
Replacement Part Cost
(Percent Difference from
Average)
1 or 2 Chairs
$486
$211 (-57%)a
$859 (+77%)
3, 4, or 5 Chairs
$597
$434 (-27%)
$910 (+52%)
6 Chairs
$770
$211 (-73%)a
$1,294 (+68%)b
7 to 14 Chairs
$943
$211 (-78%)a
$1,733 (+84%)
15 Chairs
$1,289
$729 (-43%)
$1,890 (+47%)
Source: U.S. EPA, 2016e.
a - One amalgam separator in this model dental office size category offers reusable replacement parts (i.e., annual
costs equal $0).
b - Upper-bound annual cost based on replacing entire amalgam separator.
Looking at the conservative, upper-bound estimate of replacement part costs, the final
rule would cost dental offices between $859 and $1,890 per year, depending on the size of the
dental office. EPA found that dental offices have a wide selection of amalgam separator models
and associated costs. Using the upper-bound estimate of total annual costs, EPA determined that
the final rule is affordable (see the economic analysis in the economic analysis 10).
16.4.3 Sensitivity Analysis for Amalgam Separator Maintenance Costs
The cost for maintaining the amalgam separator at a dental office is based on a number of
factors: 1) frequency of maintenance; 2) time needed to complete maintenance activities; and 3)
labor rate. For the costing analysis, EPA assumed maintenance would be performed by a dental
assistant every two weeks and that each maintenance session would take 15 minutes (on
average). Maintenance activities may include visual checks of the system (e.g., check fill line) or
replacing the canister, filter, or cartridge as recommended by the manufacturer. As part of the
literature review, EPA found that the changing of the replacement parts (e.g., canister, filter, or
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Chapter 16—Quality Assurance Activities for the Dental Category Costing and Loading Analyses
cartridge) may occur as frequently once per week to once per year (U.S. EPA, 2008). The
frequency of maintenance depends on manufacturer's recommendation and the number of dental
amalgam placements and removals performed by the dental office. The assumption of biweekly
maintenance for the amalgam separator is highly conservative in view of the range of
maintenance recommendations of the separator manufacturers (see Chapter 6). This comprises
one of the larger cost elements for smaller office sizes (1-2 chairs or 3-5 chairs).
EPA compared the range of annual costs incurred by model dental offices using various
frequency of maintenance activities - i.e., annually (lower-bound cost) to weekly (upper-bound
cost) (U.S. EPA, 2016e). The annual costs include labor costs to perform the maintenance
activity and labor costs to maintain the records (assumed to be 5 minutes per activity). Table
16-6 presents the range of annual maintenance costs for all model dental office sizes based on
varying frequency of maintenance.
Table 16-6. Range of Annual Maintenance Costs ($2016) Based on Frequency of
Maintenance
Frequency of
Maintenance
Annual Maintenance Cost ($2016)
Maintenance Activity
Recordkeeping
Total b
Weekly
$231
$77
$308
Biweekly3
$115
$38
$154
Monthly
$53
$18
$71
Biannually
$9
$3
$12
Annually
$4
$1
$6
Source: U.S. EPA, 2016a; U.S. EPA, 2016e.
a - EPA used this annual cost to calculate incremental compliance costs for dental offices,
b - Total annual cost may not equal summation of maintenance and recordkeeping costs due to rounding.
Based on manufacturer recommendations for amalgam separator replacement parts, EPA
found that filters, cartridges, canisters, and collection containers are mostly likely replaced at a
frequency of every six to 12 months. Annual maintenance costs would then be over ninety
percent lower than the estimate included in the annual incremental compliance costs for the final
rule. However, as a conservative estimate, EPA assumed biweekly maintenance.
EPA determined the impact that the range of maintenance costs (based on varying
frequency) has on the total annual costs incurred by dental offices. Table 16-7 presents the
annual costs for dental offices based on biweekly maintenance (used for final rule), annual
maintenance (lower-bound cost), and weekly maintenance (upper-bound cost) for each model
dental office size group.
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Chapter 16—Quality Assurance Activities for the Dental Category Costing and Loading Analyses
Table 16-7. Total Annual Incremental Compliance Costs Based on the Range of
Maintenance Frequency by Model Dental Office
Model Dental Office
(Chair Size)
Annual Incremental Compliance Costs ($2016)
Costs for Final
Rule, Biweekly
Maintenance
Lower-Bound Cost, Annual
Maintenance
(Percent Difference)
Upper-Bound Cost, Weekly
Maintenance
(Percent Difference)
1 or 2 Chairs
$486
$338 (-30%)a
$640 (+32%)
3, 4, or 5 Chairs
$597
$449 (-25%)
$751 (+26%)
6 Chairs
$770
$622 (-19%)a
$924 (+20%)b
7 to 14 Chairs
$943
$795 (-16%)a
$1,097 (+16%)
15 Chairs
$1,289
$1,141 (-11%)
$1,443 (+12%)
Source: U.S. EPA, 2016e.
For all model dental office size groups, the annual incremental compliance costs using
the lower-bound maintenance cost and upper-bound maintenance cost are within 32 percent of
the annual incremental compliance costs used to evaluate the final rule. Based on the range of
maintenance frequencies, the final rule would cost smaller dental offices between $338 and $640
per year (1 or 2 chairs) and $449 an $751 per year (3,4, or 5 chairs).
The O&M costs are 72 percent of the total costs and therefore comprise a cost driver in
this analysis. As noted above, EPA assumed biweekly maintenance of all amalgam separators
even though this is one of the most frequent maintenance intervals identified in the amalgam
separators evaluated. EPA found that the annual compliance costs, even accounting for biweekly
maintenance, are affordable (see the economic analysis in Chapter 10).
16.5 Sensitivity Analysis for Loadings
EPA completed sensitivity analyses for the loadings calculations to evaluate the impact of
certain input data on baseline and post-compliance mercury loadings. EPA evaluated the
following input data: number of amalgam placements, number of amalgam removals, removal
efficiency of chair-side traps and vacuum filters, and quantity of dissolved mercury in dental
office wastewater. EPA also conducted a sensitivity analysis on the removal of mercury at
POTWs.
16.5.1 Sensitivity Analysis for Number of Amalgam Placements Performed Annually by
Dental Offices
The input data with the most impact on the calculated pollutant loadings are the number
of placements and removals of dental amalgam nationwide. In EPA's loadings analysis,
placements accounted for 6.5 percent of all mercury entering dental office wastewater annually.
The use of dental amalgam is declining due to a number of factors such as alternative filling
types (e.g., composites) and improved dental health. For the loadings analysis, EPA used input
data from a 2005 study that reported ADA's estimated number of placements in 1999 (71
million). In 2009, the Food and Drug Administration (FDA) estimated that the use of dental
amalgam for fillings in 2016 will only be 41 million, a decrease of 42 percent (74 FR 38685).
Similarly, the number of removals will likely decrease over time (albeit with a delay) based on
less use of dental amalgam as a filling material.
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Chapter 16—Quality Assurance Activities for the Dental Category Costing and Loading Analyses
EPA conducted a sensitivity analysis on the loadings calculations to determine the impact
that the number of dental amalgam placements (or restorations) has on the loadings analysis.
EPA compared the amount of mercury entering dental office wastewaters annually using two
different number of annual placements: 71 million amalgam fillings (quantity used as input to the
analysis) and 41 million amalgam fillings. EPA calculated the mercury in dental office
wastewaters from amalgam placements to be 2.4 tons per year and 1.4 tons per year,
respectively. The total mercury in the wastewater at dental offices (i.e., accounting for
placements and removals) decreased by 3 percent, from 37.2 tons per year to 36.2 tons per year,
when the quantity of amalgam filling placements decreased by 42 percent (U.S. EPA, 2016c;
U.S. EPA, 2016d).
EPA determined the impact that the reduced number of placements has on the total
mercury discharged to POTWs (accounting for removal technology at the dental office) and from
POTWs to surface waters. Table 16-8 presents the results of the comparison.
Table 16-8. Impact of Dental Amalgam Placements on Annual Mercury Loadings
Number of Amalgam
Placements a
Total Annual Mercury Loadings
Discharged to POTW
(lbs/yr)
Discharge to Surface
Waters (lbs/yr)
Percent Difference
Total Discharge
Baseline Pollutant Loadings
71 million b
10,200
1,003
NA
41 million
9,960
976
-3%
Post-Compliance Pollutant Reductions
71 million b
10,100
992
NA
41 million
9,850
965
-3%
Post-Compliance Pollutant Loadings
71 million b
115
11.2
NA
41 million
111
10.9
-3%
Source: U.S. EPA, 2016c; U.S. EPA, 2016d.
Acronyms: lbs/yr (pounds per year); NA (not applicable).
a - EPA used 71 million amalgam placements as input to the loadings analysis for the final rule based on a 2005
study. In 2009, the FDA estimated that the use of dental amalgam for fillings in 2016 will only be 41 million. EPA
determined the impact that the number of dental amalgam placements lias on the annual mercury loadings,
b - Number of amalgam placements used in the loadings analysis for the final rule.
Based on 41 million placements per year, the total annual loading of mercury to POTWs
is 9,960 pounds per year (lbs/yr) (4.98 tons per year), a decrease of 3 percent compared to the
loadings analysis (71 million placements). The total annual loading of mercury to surface waters
is 111 lbs/yr (41 million placements), compared to the loadings analysis estimate of 115 lbs/yr.
Although this analysis shows that the mercury loadings in EPA's analysis may be slightly higher
assuming larger number of placements, the alternate data only changes the total loadings by -3
percent.
Another set of data (in comments from NACWA) suggested 52 million restorations per
year. The FDA data for 41 million is a lower value than the 52 million, and the total loadings
changed by less than 3 percent, therefore EPA simply notes the alternative data from NACWA
would change total loadings by approximately 2 percent.
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Chapter 16—Quality Assurance Activities for the Dental Category Costing and Loading Analyses
16.5.2	Sensitivity Analysis for Number of Amalgam Removals Performed Annually by
Dental Offices
In EPA's loadings analysis, removals accounted for 94 percent of all mercury entering
dental office wastewater. The rate of dental amalgam removals is based on studies prior to 2005;
however, EPA did not identify any more recent estimates. For the loadings analysis, EPA
assumed 710 amalgam removals each year per general dentist and 440 amalgam removals each
year per specialty dentist. Based on the number of dentists by type of practice (ADA, 2016),
EPA estimated that dental offices performed 117 million amalgam removals each year. While
some data suggests fewer placements and restorations are occurring, the dental amalgam already
in place in people's mouths would still need to be removed, and this would occur over a period
of several decades. Even if EPA were to assume a one-third reduction in removals, and thus a
one-third reduction in loads, the discharge of several tons of mercury per year to POTWs is
significant. This scenario would not change the POTW pass-through analysis. Because one-third
fewer removals occur under this scenario, and approximately one-third fewer dentists would
incur the costs of amalgam separators, thus there would be no change in EPA's cost
effectiveness. The final rule requires dental offices to collect mercury waste at the point of
generation, rather than allowing mercury to continue to POTWs where it may be discharged to
surface waters or become part of the POTW biosolids, whose management may result in diffuse
releases of the mercury into the environment (see Chapter 13).
16.5.3	Sensitivity Analysis on the Efficiency of Chair-Side Traps and Vacuum Filters
EPA used treatment capture efficiencies for well-operated chair-side traps and vacuum
filters to estimate mercury loadings. An estimated 20 percent of dental offices operate only chair-
side traps (i.e., no vacuum filter) (Vandeven & McGinnis, 2005). EPA used an amalgam removal
efficiency of 68 percent for chair-side traps; however, the range of efficiencies reported is 60 to
75 percent. Therefore, the mercury and metal loadings currently discharged may be higher or
lower at a particular dental office. EPA did not have data on the range of removal efficiencies for
chair-side traps and vacuum filters (combined), therefore the variability associated with the
capture efficiency used for the loadings analysis (78 percent)59 is not known. However, EPA
acknowledges that actual removals at individual dental offices will vary.
EPA estimated the mercury loadings for the range of chair-side trap only capture
efficiencies. Next, EPA estimated mercury loadings for the range of chair-side trap and vacuum
filter (combined) capture efficiencies. EPA selected a range of 68 to 81 percent; the 68 percent is
the capture efficiency used for chair-side traps only in the loadings analysis and 81 percent is the
efficiency (prior to weighted-average calculations) reported in Vandeven and McGinnis, 2005.
Table 16-9 and Table 16-10 present the results baseline and post-compliance mercury loadings
for each range of capture efficiencies.
59 EPA's data source for the capture efficiency for chair-side traps and vacuum filters is Vandeven and McGinnis,
2005. The 78 percent capture efficiency is the weighted-average amalgam removal efficiencies at dental offices
(those using chair-side traps only and those using both chair-side traps and vacuum filters).
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Chapter 16—Quality Assurance Activities for the Dental Category Costing and Loading Analyses
Table 16-9. Impact of Chair-Side Trap Capture Efficiencies on Annual Mercury
Loadings
Chair-Side Trap Capture
Efficiency
Total Annual Mercury Loadings
Discharged to POTW
(lbs/yr)
Discharge to Surface
Waters (lbs/yr)
Percent Difference
Total Discharge
Baseline Pollutant Loadings
60 percent
11,400
1,120
+12%
68 percenta
10,200
1,003
NA
75 percent
9,200
901
-10%
Post-Compliance Pollutant Reductions
60 percent
11,300
1,109
+12%
68 percenta
10,100
992
NA
75 percent
9,080
890
-10%
Post-Compliance Pollutant Loadings b
60 percent
115
11.2
0%
68 percenta
115
11.2
NA
75 percent
115
11.2
0%
Source: U.S. EPA, 2016c; U.S. EPA, 2016d.
Acronyms: lbs/yr (pounds per year); NA (not applicable).
a - Chair-side trap capture efficiency used in the loadings analysis for the final rule.
b -For the post-compliance pollutant loadings, EPA assumed that all dental offices will install amalgam separators
and use a filter on their vacuum system. The post-compliance loadings calculations are based on the removal
efficiency of the chair-side trap and vacuum filter (combined) and the amalgam separator.
Table 16-10. Impact of Chair-Side Trap and Vacuum Filter (Combined) Capture
Efficiencies on Annual Mercury Loadings
Chair-Side Trap Capture
Efficiency
Total Annual Mercury Loadings
Discharged to POTW
(lbs/yr)
Discharge to Surface
Waters (lbs/yr)
Percent Difference
Total Discharge
Baseline Pollutant Loadings
68 percent
12,700
1,247
+24%
78 percenta
10,200
1,003
NA
81 percent
9,490
930
-7%
Post-Compliance Pollutant Reductions
68 percent
12,600
1,231
+24%
78 percenta
10,100
992
NA
81 percent
9,390
921
-7%
Post-Compliance Pollutant Loadings
68 percent
167
16.3
+46%
78 percenta
115
11.2
NA
81 percent
99.0
9.70
-14%
Source: U.S. EPA, 2016c; U.S. EPA, 2016d.
Acronyms: lbs/yr (pounds per year); NA (not applicable).
a - Capture efficiency of chair-side trap and vacuum filter used in the loadings analysis for the final rule.
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Chapter 16—Quality Assurance Activities for the Dental Category Costing and Loading Analyses
The capture efficiency of chair-side traps impacts the baseline pollutant loadings and
post-compliance pollutant reductions; however, the efficiency has no impact on the post-
compliance loadings. To calculate the post-compliance pollutant loadings, EPA assumed that all
dental offices will install amalgam separators. In order to operate the amalgam separator, the
dental office must have a vacuum system and EPA assumed a filter would be part of the post-
compliance treatment technology. The post-compliance loadings calculations are based on the
removal efficiency of the chair-side trap and vacuum filter (combined) and the amalgam
separator.
The analysis shows that the pollutant loadings from dental offices are impacted by the
capture efficiency of these control devices, along with the capture efficiency of the amalgam
separators. However, EPA found that the range in pollutant loadings is reasonable. In all cases,
the final rule will result in more than 9,000 pounds of mercury being removed from discharges to
POTWs each year.
16.5.4 Sensitivity Analysis for Dissolved Mercury Concentration in the Wastewater
To simply for the pollutant loadings analysis, EPA assumed the dissolved mercury in the
dental office wastewater was negligible. Therefore, EPA applied control technology removal
efficiencies to the estimated total mercury entering wastewater at the dental office and
discharging to the POTW. Based on sample data included in Stone, 2004, EPA found this
assumption to be reasonable. The study reported that between 94.88 to 99.87 percent of total
mercury in dental office wastewater was bound to the amalgam particle. The remaining percent
of the total mercury was comprised of elemental mercury, ionic mercury, and monomethyl
mercury.
Dissolved mercury is not controlled by chair-side traps, vacuum filters, or amalgam
separators. Therefore, dissolved mercury in dental office wastewater will not be captured by the
control technology and will discharge to the POTW. To determine the impact that the
concentration of dissolved mercury has on the pollutant loadings passing through the dental
office control technologies, EPA used the percent of mercury bound to amalgam particles to
estimate potential range of dissolved mercury in the wastewater (0.13 to 5.12 percent).
EPA estimated that dental offices generate 37.2 tons per year of mercury in the
wastewater. Assuming 0.13 to 5.12 percent mercury becomes dissolved in the wastewater, the
dissolved mercury loadings passing through control technologies at the dental office ranges from
0.048 to 1.90 tons per year. This would result in 5.16 to 6.76 tons of total mercury discharging to
the POTW (after accounting for baseline treatment of particulate mercury). In the loadings
analysis for the final rule, EPA estimated 5.12 tons per year of mercury discharges to POTWs (0
percent dissolved mercury in the wastewater). Based on this sensitivity analysis, the dissolved
mercury could increase the total mercury discharged to POTWs by one to 32 percent (U.S. EPA,
2016d).
16.6 NACWADATA
In determining whether pollutants pass through a POTW when considering the
establishment of categorical pretreatment standards, EPA compares the median percentage of the
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Chapter 16—Quality Assurance Activities for the Dental Category Costing and Loading Analyses
pollutant removed by POTWs achieving secondary treatment with the median percentage of the
pollutant removed by facilities meeting BAT effluent limitations. EPA deems a pollutant to pass
through a POTW when the percentage removed by POTWs is less than the percentage removed
by direct dischargers complying with BPT/BAT effluent limitations. Historically, EPA's primary
source of POTW removal data is its 1982 "Fate of Priority Pollutants in Publicly Owned
Treatment Works" (also known as the 50 POTW Study). This well documented study presents
data on the performance of 50 POTWs achieving secondary treatment in removing toxic
pollutants.
In response to the proposed rule, the National Association of Clean Water Agencies
(NACWA) cited a voluntary study of its member POTWs, and suggested their study data would
better represent POTW mercury removals today than the 50 POTW Study. In fully considering
these data, EPA analyzed the voluntary survey including data from 41 POTWs and found that
numerous data would not satisfy the data editing criteria applied to the 50 POTW Study. The
NACWA data included data points representing combined data rather than raw data, order of
magnitude outlier concentrations, and incorrectly reported units of measure. Other discrepancies
between data and analyses from the 50 POTW Study and NACWA survey calculations include
upward bias of using data from voluntary respondents, representing non-detect influent
concentrations as zero rather than the actual reported value, inclusion of several POTWs using
BNR (biological nutrient removal) and other advanced treatment expected to perform better than
secondary, overrepresentation of areas with existing dental amalgam reduction programs, and
underrepresentation of certain geographical areas. Sensitivity analyses around these data are
found in the record (U.S. EPA, 2016b).
EPA has determined these data are not representative of POTWs with secondary
treatment, and has concluded the 50 POTW Study data are the best data for assessing POTW
mercury removals. Therefore, EPA is not using these alternative data for assessing POTW pass
through. However, EPA found that even if EPA were to accept these data, the median POTW
mercury removal as presented in these alternative data under the most data inclusive scenario
(e.g. not applying the full data editing criteria EPA applied to the 50 POTW Study data) is 94
percent. This median mercury removal is not comparable to the 50 POTW study as stated above.
Nevertheless, if the results of this sensitivity analysis were used to evaluate POTW pass through
as described in Chapter 5, EPA concludes there is pass through.
16.7 References
AB Dental Trends. 2016. The Field Proven Rasch Amalgam Separator (website).
http://www.amalgamseparation.comA Accessed July. Document Control Number (DCN)
DA00475.
ADA. 2016. Supply of Dentists in the U.S. 2001 - 2015. MS Excel™ file. DCN DA00460.
MCES (Metropolitan Council Environmental Services). 2009. Revised - Features of Approved
Amalgam Separators. March. DCN DA00070.
National Maternal & Child Oral Health Resource Center. 2011. Safety Net Dental Clinic
Manual: Clinic Management, http://dentalclinicmanual.com/chapt6/3 6.html#opperdent
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Chapter 16—Quality Assurance Activities for the Dental Category Costing and Loading Analyses
NH (New Hampshire). 2015. Approved Amalgam Separators - Updated September 2015. DCN
DA00474.R&D Services. 2016. The Amalgam Collector: Pricing and How to Order
(website), http://theamalgamcollector.com/price.htm. Accessed July. DCN DA00473.
R&D Services. 2016. The Amalgam Collector: Pricing and How to Order (website).
http://theamalgamcollector.com/price.htm. Accessed July. DCN DA00473.
Rebec Environmental. 2016 Amalgam Separators (website).
http://rebecenvironmental.com/products/amalgam-separators/. Accessed July. DCN
DA00472.
Stone, M.E. 2004. The Effect of Amalgam Separators on Mercury Loading to Wastewater
Treatment Plants. Journal of the California Dental Association, 32(7):593-600. DCN
DA00018.
U.S. Air Force (USAF). 2011. Synopsis of Dental Amalgam Separators. January 24. Dental
Evaluation and Consultation Service. DCN DA00079.
U.S. EPA. 2008. Health Services Industry Detailed Study: Dental Amalgam. EPA-821-R-08-014.
August. DCN DA00057.
U.S. EPA, 2016a. Amalgam Separator Cost Breakdown by Number of Chairs. MS Excel™ file.
July. DCN DA00454.
U.S. EPA. 2016b. Amalgam Separator Installation Costs. MS Excel™ file. Office of Water.
Washington, DC. DCN DA00455.
U.S. EPA 2016c. Dental Office Cost Calculations. MS Excel™ file. Office of Water.
Washington, DC. DCN DA00456.
U.S. EPA. 2016d. Sensitivity Analysis for Loading Calculations. MS Excel™ file. Office of
Water. Washington, DC. DCN DA00492.
U.S. EPA. 2016e. Sensitivity Analysis for Cost Calculations. MS Excel™ file. Office of Water.
Washington, DC. DCNDA00491.
Vandeven, J., and S. McGinnis. 2005. An Assessment of Mercury in the Form of Amalgam in
Dental Wastewater in the United States. Water, Air, and Soil Pollution, 164:349-366.
DCN DA00163
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Chapter 17—Glossary and List of Acronyms
Chapter 17
Glossary and List of Acronyms	
ADA - American Dental Association.
AMSA - Association of Metropolitan Sewerage Agencies.
Amalgam - dental filling that is formed using liquid mercury and a metal powder mixture, often
supplied in capsules. Amalgam fillings contain approximately 49 percent mercury and a mixture
of metals—silver, tin, copper, and sometimes zinc, indium, or palladium - in the powder
mixture.
Amalgam Separator - treatment technology used at dental offices to remove solid particulates
from the wastewater.
BAT - The best available technology economically achievable, as described in Sec. 304(b)(2) of
the Clean Water Act.
BMP - Best management practice. The Clean Water Act authorize EPA to prescribe BMPs as
part of effluent limitations guidelines and standards, or as part of a permit.
BPT - The best practicable control technology currently available, as described in Sec. 304(b)(1)
of the Clean Water Act.
Categorical Pretreatment Standards - Limitations on pollutant discharges to POTWs
promulgated by EPA in accordance with Section 307 of the Clean Water Act that apply to
specified process wastewaters of particular industrial categories.
CFR- Code of Federal Regulations, published by the U.S. Government Printing Office. A
codification of the general and permanent rules published in the Federal Register by the
Executive departments and agencies of the federal government.
CIU - Categorical Industrial User. An industrial user subject to national categorical pretreatment
standards.
Control Authority - POTW, state, or EPA Region that is responsible for permitting, sampling,
and inspecting industrial users that discharge to the POTW. The Control Authority is (1) the
POTW if the POTWs submission for its pretreatment program (§403.3(t)(l)) has been approved
in accordance with the requirements of §403.11; or (2) the Approval Authority (state or EPA
Region) if the submission has not been approved.
CWA - Clean Water Act. Federal legislation enacted by Congress to "restore and maintain the
chemical, physical, and biological integrity of the Nation's waters" (Federal Water Pollution
Control Act of 1972, as amended, 33 U.S.C. 1251 et seq.).
DCN - Document Control Number.
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Chapter 17—Glossary and List of Acronyms
Direct Discharge - The discharge of a pollutant or pollutants directly to a water of the United
States.
Discharge - The conveyance of wastewater to: (1) United States surface waters such as rivers,
lakes, and oceans, or (2) a publicly owned, privately owned, federally owned, combined, or other
treatment works.
DMR - Discharge Monitoring Report.
Effluent Limitation - Any restriction, including schedules of compliance, established by a state
or the Administrator on quantities, rates, and concentrations of chemical, physical, biological,
and other constituents that are discharged from point sources into navigable waters, the waters of
the contiguous zone, or the ocean. (CWA Sections 301(b) and 304(b).)
ETV - Environmental Technologies Verification.
EPA - U.S. Environmental Protection Agency.
FDA - Food and Drug Administration.
FFDCA - Federal Food, Drug, and Cosmetic Act.
Filtration - A process for removing particulate matter from water by passage through porous
media.
FR - Federal Register, published by the U.S. Government Printing Office, Washington, D.C. A
publication making available to the public regulations and legal notices issued by federal
agencies.
Indirect Discharge - The discharge of a pollutant or pollutants to a POTW.
Ion exchange - Process using a resin formulated to adsorb cationic or anionic species.
ISO - International Organization for Standardization.
IU - Industrial User.
Loadings - Mass of pollutants being discharged in the wastewater from dental offices to POTWs
and from POTWs to surface waters.
Mercury - As it pertains to the dental industry, mercury is a component of amalgam fillings. As
found in wastewater, mercury is a concern to human health because it is a persistent,
bioaccumulative, toxic element; certain microorganisms can change mercury into
methylmercury, a highly toxic form that builds up in fish, shellfish, and animals that eat fish.
Mono-fill - An ultimate disposal technique for wastewater treatment plant sludge in which the
sludge is applied to a landfill designed for sludge only.
MOU -Memorandum of Understanding.
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Chapter 17—Glossary and List of Acronyms
NACWA - National Association of Clean Water Agencies.
NAICS - North American Industry Classification System. This system is a unique method for
classifying business establishments. Adopted in 1997 to replace the old Standard Industrial
Classification (SIC) system, it is the industry classification system used by the statistical
agencies of the United States.
NPDES - The National Pollutant Discharge Elimination System, authorized under Sec. 402 of
the Clean Water Act. NPDES requires permits for discharge of pollutants from any point source
into waters of the United States.
NSPS - New source performance standards, as described in Sec. 306 of the CWA.
OSHA - Occupational Safety and Health Administration.
POTW - Publicly owned treatment works, as defined at 40 CFR 403.3(o). POTWs are generally
any state or municipality-owned sewage treatment plant that recycles, reclaims, or treats liquid
municipal sewage and/or liquid industrial wastes.
PPA - Pollution Prevention Act of 1990 (42 U.S.C. 13101 et seq., Pub.L. 101-508, November 5,
1990).
Pretreatment -The reduction of the amount of pollutants, the elimination of pollutants, or the
alteration of the nature of pollutant properties in wastewater prior to or in lieu of discharging or
otherwise introducing such pollutants into a POTW.
Pretreatment Standard - A regulation that establishes industrial wastewater effluent quality
required for transfer to a POTW (CWA Section 307(b)).
PSES - Pretreatment standards for existing sources, as described in Sec. 307(b) of the CWA.
PSNS - Pretreatment standards for new sources, as described in Sec. 307(b) and (c) of the CWA.
QSC - Quicksilver Caucus of the Environmental Council of States.
RCRA - Resource Conservation and Recovery Act (PL 94-580) of 1976, as amended (42 U.S.C.
6901, et seq.).
SBA - Small Business Administration.
Sedimentation - Separation of solids and liquids from mixtures (solid settling).
SIC - Standard Industrial Classification. A numerical categorization system used by the U.S.
Department of Commerce to catalogue business entities and economic activity. SIC codes refer
to the products, or groups of products, produced or distributed, or to services rendered, by an
operating establishment. SIC codes are used to group establishments by the goods and services
they provide and the economic activities in which they are engaged. SIC codes often denote a
facility's primary, secondary, tertiary, etc. economic activities.
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Chapter 17—Glossary and List of Acronyms
SIU - Significant Industrial User. An indirect discharger that is the focus of control efforts under
the national pretreatment program. This includes all indirect dischargers subject to national
categorical pretreatment standards, and all other indirect dischargers that contribute 25,000
gallons per day or more of process wastewater, or which make up five percent or more of the
hydraulic or organic loading to the POTW, subject to certain exceptions.
Sludge - The accumulated solids separated from liquids during processing (treatment).
Surface Waters - Waters of the United States including, but not limited to, oceans and all
interstate and intrastate lakes, rivers, streams, creeks, mudflats, sand flats, wetlands, sloughs,
prairie potholes, wet meadows, playa lakes, and natural ponds.
TCLP - Toxicity Characteristic Leaching Procedure. See 40 CFR 261.24.
TRI - Toxics Release Inventory.
TWF - Toxic Weighting Factor. A factor developed for various pollutants using a combination
of toxicity data on human health and aquatic life. EPA uses toxic weighting factors in
determining the amount of toxicity that a pollutant may exert on human health and aquatic life
relative to other pollutants.
TWPE - Toxic Weighted Pound-Equivalent. Pound of pollutant adjusted for relative toxicity;
determined by multiplying the pound of pollutant by the TWF.
VSQG- Very Small Quantity Generators.
Wastewater - For this document, water emanating from dental office.
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