United States Office of Water EPA-821-R-14-006

Environmental Protection Washington, DC 20460 October 2014

Agency

Technical and Economic 

Development Document for 

the Proposed Effluent 

Limitation Guidelines and 

Standards for the Dental

Category
Technical and Economic Development Document 

for the Proposed Effluent Limitation Guidelines 

and Standards for the Dental Category 

(40 CFR 441)

EPA-821-R-14-006

October 2014

U.S. Environmental Protection Agency

Office of Water (4303T)

Engineering and Analysis Division

1200 Pennsylvania Avenue, NW

Washington, DC 20460
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

i 
Table of Contents

TABLE OF CONTENTS

Page

SECTION 1 BACKGROUND ............................................................................................................. 1-1

1.1 Legal Authority .................................................................................................... 1-1

1.2 Regulatory Background ....................................................................................... 1-1

1.2.1 Clean Water Act ....................................................................................... 1-1

1.2.2 Pollution Prevention Act .......................................................................... 1-4

1.2.3 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 State and Local Programs ........................................................................ 1-6

1.4 References ............................................................................................................ 1-6

SECTION 2 SUMMARY AND SCOPE................................................................................................. 2-1

2.1 Summary of the Proposed Rule ........................................................................... 2-2

2.2 Applicability of the Proposed Rule ...................................................................... 2-3

2.3 Subcategorization ................................................................................................. 2-3

2.4 References ............................................................................................................ 2-4

SECTION 3 DATA COLLECTION ACTIVITIES ................................................................................... 3-1

3.1 Health Services Industry Detailed Study ............................................................. 3-1

3.2 Literature Review................................................................................................. 3-1

3.3 Meetings with Stakeholders ................................................................................. 3-2

3.3.1 Environmental Council of the States ....................................................... 3-2

3.3.2 Environmental Organizations .................................................................. 3-2

3.3.3 American Dental Association (ADA) ...................................................... 3-2

3.3.4 National Association of Clean Water Agencies (NACWA) .................... 3-2

3.4 Amalgam Separator Manufacturers (Vendor Contacts) ...................................... 3-2

3.5 Air Force Study .................................................................................................... 3-3

3.6 References ............................................................................................................ 3-3

SECTION 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

SECTION 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 ................................................................................ 5-1

5.3 Pollutants of Concern and Pass Through ............................................................. 5-3

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Table of Contents

5.3.1 POTW Pass Through Analysis ................................................................ 5-3

5.4 References ............................................................................................................ 5-4

SECTION 6 CURRENT NATIONAL, STATE, AND LOCAL DENTAL MERCURY REDUCTION

PROGRAMS ........................................................................................................................ 6-1

6.1 National Dental Amalgam Requirements and Guidance ..................................... 6-1

6.1.1 U.S. EPA Strategies to Reduce Mercury Discharges .............................. 6-1

6.1.2 Occupational Safety and Health Administration ..................................... 6-2

6.1.3 Food and Drug Administration ................................................................ 6-3

6.1.4 American Dental Association .................................................................. 6-3

6.2 State Dental Amalgam Requirements .................................................................. 6-5

6.3 Local Dental Amalgam Requirements ............................................................... 6-11

6.4 Voluntary Programs ........................................................................................... 6-14

6.4.1 Voluntary Programs with High Participation Rates............................... 6-14

6.4.2 Voluntary Programs with Low Participation Rates ............................... 6-18

6.4.3 Summary of Participation Rates in Voluntary Programs ....................... 6-20

6.5 References .......................................................................................................... 6-21

SECTION 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 Best Management Practices ................................................................................. 7-7

7.4 References ............................................................................................................ 7-8

SECTION 8 REGULATORY OPTIONS ............................................................................................... 8-1

8.1 Pretreatment Standards for Existing Sources (PSES) .......................................... 8-1

8.1.1 Requirements ........................................................................................... 8-2

8.2 Pretreatment Standards for New Sources (PSNS) ............................................... 8-3

8.3 References ............................................................................................................ 8-4

SECTION 9 COSTS OF TECHNOLOGIES ........................................................................................... 9-1

9.1 Methodology for Developing Model Dental Office Costs .................................. 9-1

9.1.1 Model Compliance Costs for Dental Offices Without Amalgam 

Separators ................................................................................................. 9-2

9.1.2 Model Compliance Costs for Dental Offices Currently Using 

Amalgam Separators ................................................................................ 9-7

9.2 Reporting Requirements and BMP Costs ............................................................ 9-7

9.3 Methodology for Developing Costs for Institutional Facilities ........................... 9-8

9.4 References ............................................................................................................ 9-8

SECTION 10 ECONOMIC IMPACTS FOR THE DENTAL INDUSTRY ................................................... 10-1

10.1 Overview of Dental Offices Potentially Subject to Proposed Regulation ......... 10-1

10.1.1 Number of Dental Offices Potentially Subject to the Proposed 

Regulation 10-1

10.1.2 Adjustments to Account for Baseline Status ......................................... 10-3

10.2 Summary of the Proposed Regulation And Compliance Costs ......................... 10-6

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Table of Contents

10.2.1 Summary of Compliance Costs ............................................................. 10-6

10.2.2 Linking Compliance Costs By Number of Chairs to Dental Offices 

by Revenue Range ............................................................................... 10-10

10.3 Estimated Cost of Compliance to Dental Offices ............................................ 10-14

10.3.1 Economic Impact of Compliance Costs ............................................... 10-14

10.4 Social Cost of the Proposed 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

SECTION 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 ................................. 11-4

11.1.5 Total Annual Baseline Discharges to POTWs ....................................... 11-5

11.2 National Estimate of Annual Pollutant Reductions to POTWs Associated 

with the Proposed Dental Amalgam Rule .......................................................... 11-5

11.3 National Estimate of Annual Pollutant Reductions to Surface Waters 

Associated with the Proposed Dental Amalgam Rule ....................................... 11-5

11.4 References .......................................................................................................... 11-6

SECTION 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 ................................................................................. 12-2

12.5 References .......................................................................................................... 12-3

SECTION 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 Discharges ................................................... 13-2

13.3.2 Mercury in Biosolids.............................................................................. 13-3

13.3.3 Environmental Benefits of the Proposed Dental Amalgam Rule .......... 13-3

13.4 References .......................................................................................................... 13-4

SECTION 14 NON-WATER-QUALITY IMPACTS ............................................................................ 14-1

14.1 Energy Requirements ......................................................................................... 14-1

14.2 Solid Waste Generation ..................................................................................... 14-1

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Table of Contents

14.3 Air Emissions ..................................................................................................... 14-2

14.4 References .......................................................................................................... 14-2

SECTION 15 IMPLEMENTATION.................................................................................................... 15-1

15.1 Implementation Deadline for Existing Sources ................................................. 15-1

15.2 Implementation Deadline for New Sources ....................................................... 15-1

15.3 Reporting requirements ...................................................................................... 15-1

SECTION 16 UPDATES TO GENERAL PRETREATMENT STANDARDS (40 CFR 403) ...................... 16-1

16.1 Proposed Changes to the General Pretreatment Standards ................................ 16-1

16.2 Responsibilities of the Control Authorities........................................................ 16-2

16.2.1 Noncompliance ...................................................................................... 16-2

16.2.2 Classification of Dental Offices as Non-Significant Categorical 

Industrial Users (NSCIU) ...................................................................... 16-2

SECTION 17 GLOSSARY AND LIST OF ACRONYMS ...................................................................... 17-1

v
List of Tables

LIST OF TABLES

Page 

Table 4-1. Number of Dental Offices by State (2007) ................................................................. 4-2

Table 4-2. Growth in Number of Dental Offices (1997 to 2007) ................................................ 4-3

Table 4-3. Dental Offices with NPDES Permits in ICIS-NPDES ............................................... 4-5

Table 4-4. Dental Offices with Discharge Data in ICIS-NPDES ................................................ 4-5

Table 6-1. ADA BMPs for Dental Amalgam .............................................................................. 6-3

Table 6-2. Summary of Elements of State Requirements ............................................................ 6-6

Table 6-3. Mandatory BMPs by State and Comparison to ADA BMPs a,b ................................. 6-8

Table 6-4. Voluntary BMPs by State and Comparison to ADA BMPs ..................................... 6-10

Table 6-5. Summary of Elements of Local Requirements ......................................................... 6-11

Table 6-6. Best Management Practices by Municipality ........................................................... 6-12

Table 6-7. Summary of Voluntary Programs for Reducing Dental Amalgam Releases to 

Wastewater ..................................................................................................................... 6-16

Table 7-1. Efficiency and Technology of 39 Amalgam Separators ............................................. 7-5

Table 9-1. Cost of Purchasing, Operating, and Maintaining Amalgam Separators ($2010)........9-3

Table 9-2. Summary of One Time Costs ($2010) to Model Dental Offices Without 

Amalgam Separators ........................................................................................................ 9-6

Table 9-3. Summary of Annual Costs ($2010) to Model Dental Offices Without an 

Amalgam Separator ......................................................................................................... 9-7

Table 9-4. Percentage of Recurring Costs Incurred by Dental Offices Currently Using 

Amalgam Separators ........................................................................................................ 9-7

Table 9-5. Summary of Annual Model Facility Costs ($2010) to Dental Offices Currently 

Using Amalgam Separators ............................................................................................. 9-7

Table 10-1. Dental Office Establishments by Revenue Range (NAICS 621210, Offices 

of Dentists) ..................................................................................................................... 10-3

Table 10-2. Adjusting Office Counts to Account for Baseline Amalgam Use and 

Technology in Place ....................................................................................................... 10-5

Table 10-3. Dental Office Compliance Costs by Cost Category and Number of Chairs 

(2010 dollars) ................................................................................................................. 10-7

Table 10-4. Summary of Annualized Compliance Costs for a Dental Office or Large 

Facility, Accounting for Initial Installation and Reinstallation of Amalgam 

Separators, and Operational and Certification Costs ..................................................... 10-9

Table 10-5. Distribution of the Number of Chairs in Dental Offices ...................................... 10-10

Table 10-6. Number of Chairs in Dental Offices by Revenue Range ..................................... 10-12

Table 10-7. Annualized Costs to Complying Dental Offices by Number of Chairs ............... 10-14

vi 
List of Tables

Table 10-8. Revenue Range/Number-of-Chairs Combinations for Cost Impact Analysis ..... 10-15

Table 10-9. Cost-to-Revenue Impact Summary ...................................................................... 10-18

Table 10-10. Cost-to-Revenue Impact Summary by Number of Chairs ................................. 10-19

Table 10-11. Comparing Total Initial Outlay to Baseline Assets ............................................ 10-20

Table 10-12. Composition of Dental Equipment for Six-Chair Office by Equipment Life ... 10-22

Table 10-13. Initial and Annual Replacement Outlay for Startup Dental Office by 

Number of Chairs ......................................................................................................... 10-23

Table 10-14. Comparing Total Initial Compliance Outlay to Steady State Annual 

Replacement Outlay by Number of Chairs (Section 10.3.1.3) .................................... 10-24

Table 10-15. Comparing Total Initial Compliance Outlay to Initial Outlay by Number of 

Chairs (Section 10.3.1.4) ............................................................................................. 10-24

Table 10-16. Compliance Costs on a Social Cost Basis for Proposed Dental Amalgam 

Rule .............................................................................................................................. 10-26

Table 10-17. Summary of Social Cost for Proposed Dental Amalgam Rule .......................... 10-27

Table 10-18. Cost-to-Revenue Impact Analysis for Small Entities ......................................... 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 (Million $) ............................................................. 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 

Dischargesa

 ..................................................................................................................... 12-2

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 Time for Dental Offices Potentially Subject to the Proposed 

Rule ................................................................................................................................ 15-1

vii 
List of Figures

LIST OF FIGURES

Page 

Figure 5-1. Typical Amalgam Separator Plumbing Configuration in a Dental Office ................ 5-2

viii
Section 1 - Background

SECTION 1

BACKGROUND

This section provides background information on the development of effluent limitation

guidelines and standards proposed for the Dental Category. Sections 1.1 and 1.2 present the legal 

authority and discuss the regulatory background for the proposed rule, respectively. Section 1.3

provides a history of activities related to Dental Category rulemaking. 

1.1 LEGAL AUTHORITY

The U.S. Environmental Protection Agency (EPA) is proposing effluent limitation 

guidelines and standards (ELGs) for the Dental Category (40 CFR 441) under the authority 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 also authorizes 

EPA to establish national technology-based effluent limitation guidelines and standards (effluent 

guidelines or ELGs) for discharges from different categories of point sources, such as industrial, 

commercial, and public sources. 

Congress recognized that regulating only those sources that discharge effluent directly 

into the nation's waters would not be sufficient to achieve the CWA's goals. Consequently, the 

CWA requires EPA to promulgate nationally-applicable pretreatment guidelines and standards 

that restrict pollutant discharges from facilities that discharge wastewater indirectly through 

sewers flowing to publicly owned treatment works (POTWs). See section 304(g), 307(b) and (c), 

33 U.S.C. 1314(g), and 1317(b) and (c). National pretreatment standards are established for those 

pollutants in wastewater from indirect dischargers that may pass through, interfere with or are 

otherwise incompatible with POTW operations. Generally, pretreatment standards are designed 

to ensure that wastewaters from direct and indirect industrial dischargers are subject to similar 

levels of treatment. In addition, POTWs are required to implement local treatment limits 

applicable to their industrial indirect dischargers to satisfy any local requirements. See 40 CFR 

403.5. 

Direct dischargers must comply with effluent limitations in NPDES permits. Indirect 

dischargers (who discharge through POTWs) must comply with pretreatment standards. 

1-1 
Section 1 - Background

Technology-based effluent limitations in NPDES permits are derived from effluent limitation 

guidelines (CWA sec. 301 and 304) and new source performance standards (sec. 306) 

promulgated by EPA, or are based on best professional judgment in cases where EPA has not 

promulgated an applicable effluent guideline or new source performance standard. Additional 

limitations based on water quality standards (sec. 301(b)(1)(C) and 303) may also be included in 

the permit in certain circumstances. The ELGs are established by regulation for various 

categories of industrial dischargers and are based on the degree of control that can be achieved 

using various levels of pollution control technology. 

EPA promulgates national effluent limitation guidelines and standards of performance for 

major industrial categories for three classes of pollutants: (1) conventional pollutants (total 

suspended solids, oil and grease, biochemical oxygen demand, fecal coliform, and pH); (2) toxic 

pollutants (e.g., toxic metals such as chromium, lead, mercury, nickel, and zinc; toxic organic 

pollutants such as benzene, benzo-a-pyrene, phenol, and naphthalene) as specified in sec. 307 of 

the Act; and (3) non-conventional pollutants, which are neither conventional nor toxic (e.g., 

ammonia-N, formaldehyde, and phosphorus). 

There are standards applicable to direct dischargers (dischargers to surface waters), and 

standards applicable to indirect dischargers (discharges to POTWs). The standards relevant to 

this rulemaking are summarized below. 

1. Best Available Technology Economically Achievable (BAT) 

BAT effluent limitation guidelines apply to direct dischargers of toxic and 

nonconventional pollutants. In general, BAT effluent limitation guidelines represent 

the best economically achievable performance of facilities in the industrial 

subcategory or category. The factors considered in assessing BAT include 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. The Agency has considerable discretion in assigning the weight to 

be accorded these factors. An additional statutory factor considered in setting BAT is 

economic achievability. Generally, EPA determines economic achievability on the 

basis of total costs to the industry and the effect of compliance with BAT limitations 

on overall industry and subcategory financial conditions. Where existing performance 

is uniformly inadequate, BAT may reflect a higher level of performance than is 

currently being achieved based on technology transferred from a different 

subcategory or category. BAT may be based upon process changes or internal 

controls, even when these technologies are not common industry practice. 

2. New Source Performance Standards (NSPS) 

New Source Performance Standards reflect effluent reductions that are achievable 

based on the best available demonstrated control technology. 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 best available 

demonstrated control technology for all pollutants (that is, conventional, 

1-2 
Section 1 - Background

nonconventional, and priority pollutants). In establishing NSPS, EPA is directed to 

take into consideration the cost of achieving the effluent reduction and any nonwater-quality environmental impacts and energy requirements. 

3. Pretreatment Standards for Existing Sources (PSES) 

Pretreatment standards apply to discharges of pollutants to POTWs rather than 

discharges to waters of the United States. Pretreatment Standards for Existing Sources 

(PSES) are designed to prevent the discharge of pollutants 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 limitation guidelines. 

The General Pretreatment Regulations, which set forth the framework for the 

implementation of categorical pretreatment standards, are found at 40 CFR 403. 

4. Pretreatment Standards for New Sources (PSNS) 

Like PSES, Pretreatment Standards for New Sources (PSNS) are designed to prevent 

the discharges of pollutants that pass through, interfere with, or are otherwise 

incompatible with the operation of POTWs. New indirect discharges have the 

opportunity to incorporate into their facilities the best available demonstrated 

technologies. The Agency typically considers the same factors in promulgating PSNS 

as it considers in promulgating NSPS. 

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,); Waterkeeper Alliance, Inc. v. U.S. EPA, 399 F.3d 486, 496-97, 502 (2d 

Cir. 2005), holding that EPA’s use of non-numerical effluent limitations in the form 

of Best Management Practices are effluent limitations under the CWA; and Natural 

Res. Def. Council, Inc. v. EPA, 673 F.2d 400, 403 (D.C. Cir. 1982) which states 

“section 502(11) [of the CWA] defines ‘effluent limitation’ as ‘any restriction’ on the 

amounts of pollutants discharged, not just a numerical restriction.” 

1-3 
Section 1 - Background

1.2.2 Pollution Prevention Act

The Pollution Prevention Act of 1990 (PPA) (42 U.S.C. 13101 et seq., Public Law 101-

508, November 5, 1990) "declares it to be the national policy of the United States that pollution 

should be prevented or reduced whenever feasible; pollution that cannot be prevented should be 

recycled in an environmentally safe manner, whenever feasible; pollution that cannot be 

prevented or recycled should be treated in an environmentally safe manner whenever feasible; 

and disposal or release into the environment should be employed only as a last resort..." (Sec. 

6602; 42 U.S.C. 13101 (b)). In short, preventing pollution before it is created is preferable to 

trying to manage, treat, or dispose of it after it is created. The PPA directs the Agency to, among 

other things, "review regulations of the Agency prior and subsequent to their proposal to 

determine their effect on source reduction" (Sec. 6604; 42 U.S.C. 13103(b)(2)). EPA reviewed 

this effluent guideline for incorporation of pollution prevention measures. 

According to the PPA, source reduction reduces the generation and release of hazardous 

substances, pollutants, wastes, contaminants, or residuals at the source, usually within a process. 

The term source reduction "include[s] equipment or technology modifications, process or 

procedure modifications, reformulation or redesign of products, substitution of raw materials, 

and improvements in housekeeping, maintenance, training or inventory control. The term ‘source 

reduction' does not include any practice which alters the physical, chemical, or biological 

characteristics or the volume of a hazardous substance, pollutant, or contaminant through a 

process or activity which itself is not integral to or necessary for the production of a product or 

the providing of a service" (42 U.S.C. 13102(5)). In effect, source reduction means reducing the 

amount of a pollutant that enters a waste stream or that is otherwise released into the 

environment prior to out-of-process recycling, treatment, or disposal. 

1.2.3 The National Pretreatment Program, 40 CFR 403 

The General Pretreatment Regulations of 40 CFR 403 establish responsibilities among 

federal, state, and local government; industry; and the public to implement pretreatment 

standards to control pollutants that pass through or interfere with the POTW treatment processes 

or that can contaminate sewage sludge. The regulations, which have been revised numerous 

times since originally published in 1978, consist of 20 sections and seven appendices. The 

General Pretreatment Regulations use two terms describing oversight responsibilities under those 

regulations. One is the term Control Authority. The “Control Authority” refers to the POTW if 

the POTW has an approved pretreatment program, or the Approval Authority if the program has 

not been approved. The term Approval Authority describes the party with responsibility to 

administer the National Pretreatment Program which is either a state with an approved state 

pretreatment program or, in a state without an approved pretreatment program, the EPA region 

for that state [40 CFR § 403.3(f)]. An approved pretreatment program comprises legal 

authorities, procedures, funding, local limits, enforcement response plan, and the list of 

significant industrial users, all of which the Control Authority uses to implement the General 

Pretreatment Regulations. 

The General Pretreatment Regulations apply to all nondomestic sources that introduce 

pollutants into a POTW. These sources of indirect discharges are also commonly referred to as 

Industrial Users or IUs. All IUs are subject to general pretreatment standards (40 CFR 403), 

1-4 
Section 1 - Background

including a prohibition on discharges causing “pass through” or “interference” (i.e., cause the 

POTW to violate its permits limits, or interfere with the operation of the POTW or the beneficial 

use of its sewage sludge). All POTWs with approved pretreatment programs must develop local 

limits to implement the general pretreatment standards. All other POTWs must develop such 

local limits where they have experienced “pass through” or “interference” and such a violation is 

likely to recur. There are approximately 1,500 POTWs with approved pretreatment programs and 

13,500 small POTWs that are not required to develop and implement pretreatment programs. 

1.3 REGULATORY HISTORY OF THE DENTAL CATEGORY

This section presents a brief history of activities related to Dental Category rulemaking. 

Section 1.3.1 discusses EPA’s Detailed Study of the Dental Category. Section 1.3.2 discusses the 

2008 memorandum of understanding (MOU) to reduce mercury discharges. Section 1.3.3

describes the American Dental Association’s Best Management Practices and support of a 

national rulemaking. Section 1.3.4 describes existing state and local programs for dental 

discharges. 

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? 

• 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). 

1-5 
Section 1 - Background

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 State and Local Programs 

Currently, 12 states (Connecticut, Louisiana, Maine, Massachusetts, Michigan, New 

Hampshire, New Jersey, New York, Oregon, Rhode Island, Vermont, and Washington) have 

implemented mandatory programs to reduce dental mercury discharges.1

 Additionally, at least 19 

localities similarly have mandatory dental reduction pretreatment programs. These mandatory 

programs require the use of amalgam separators and Best Management Practices. Removal 

efficiency requirements for separators in mandatory program jurisdictions vary from 95 percent

to 99 percent. See Sections 6.2 and 6.3 of this document for more details on these programs. 

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.

1 New Mexico has a similar program scheduled to go into effect in 2015.

1-6 

 
Section 2 - Summary and Scope

SECTION 2

SUMMARY AND SCOPE

Across the United States, many states and POTWs (also referred to as municipal 

wastewater treatment plants) are working to reduce discharges of mercury to POTWs. Numerous 

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). Amalgam dental fillings 

contain mercury and other metals. Mercury discharges can result when dentists dispose of old 

amalgam fillings from patients’ cavities, and dispose of excess amalgam after placing a new 

filling. 2

 A study funded by the American Dental Association (ADA) published in 2005 

estimated that dental offices contributed more than 50 percent (6.5 tons of 12.3 tons) of mercury 

entering POTWs (Vandeven and McGinnis, 2005).3

 

Mercury is a persistent and bioaccumulative pollutant with well-documented effects on 

human health. On November 6, 2013, the United States joined the Minamata Convention on 

Mercury, a new multilateral environmental agreement (not yet in force) that addresses specific 

human activities that are contributing to widespread mercury pollution. The agreement identifies 

dental amalgam as a mercury-added product regarding which certain measures should be taken. 

Specifically, the Convention lists nine measures for phasing down the use of mercury in dental 

amalgam, including promoting best environmental practices in dental facilities to reduce releases 

of mercury and mercury compounds to water and land. Nations that are parties to the Minamata 

Convention will be required to implement at least two of the nine measures addressing dental 

amalgam. 

EPA estimates that 4.4 tons of mercury from waste dental amalgam are discharged into 

POTWs (U.S. EPA, 2011a). The physical processes at POTWs remove approximately 90 percent 

of the mercury in wastewater. This mercury transfers to the biosolids (or sewage sludge) 

generated during primary and secondary treatment processes (U.S. EPA, 1982). Mercury from 

amalgam can enter the environment through the incineration, landfilling, and land application of 

sludge, or through surface water discharge from POTWs. Once deposited, certain 

microorganisms can change mercury into methylmercury, a highly toxic form that builds up in 

fish, shellfish, and animals that eat fish. Fish and shellfish are the main sources of 

methylmercury exposure to humans. 

The proposed regulations for the dental industry include pretreatment standards for the 

control of mercury in wastewater. This section summarizes the proposed rule, its application, and 

subcategorization. 

2 Other filling types, such as composite fillings, do not contain mercury or other metals.

3 EPA performs a similar calculation to estimate current mercury discharges from dental facilities. See Section 11 of 

this document.

2-1 

 
Section 2 - Summary and Scope

2.1 SUMMARY OF THE PROPOSED RULE

EPA is proposing technology-based pretreatment standards under the Clean Water Act

(CWA) for discharges of pollutants into POTWs from existing and new dental offices4 that 

discharge dental amalgam. The proposed rule would require dental offices to control the 

discharge of mercury and other metals in dental amalgam into POTWs based on the best 

available technology or best available demonstrated control technology (amalgam separators) 

and the use of best management practices (BMPs). The BMPs are (1) eliminating the flushing of 

scrap amalgam down drains and (2) cleaning chair-side traps with non-bleach, non-chlorine 

cleaners. EPA is also proposing to amend selected parts of the General Pretreatment Regulations 

(40 CFR 403) to streamline oversight requirements for the Dental Category. 

EPA expects that compliance with this proposed rule would reduce the transfer of metals 

to POTWs by 8.8 tons per year, almost half of which (4.3 tons) is mercury (U.S. EPA, 2011a). 

EPA estimates the annual cost of the proposed rule would be $44 to $49 million (U.S. EPA, 

2011b). EPA developed the proposed rule based on proper operation and maintenance of 

amalgam separators that remove at least 99.0 percent of total mercury from amalgam process 

wastewater, along with the use of the two BMPs. 

Affected dental offices could meet the standard by using, properly operating, and 

maintaining a dental amalgam separator certified to achieve at least 99.0 percent reduction of 

total mercury according to the 2008 ISO 11143 standard (ISO, 2008), performing certain BMPs, 

and certifying to this effect. Affected dental offices could also meet the standard by certifying 

that they do not install or remove amalgam. ADA recommends that its dentists use the 

technology on which the rule is based (i.e., amalgam separators and BMPs) (ADA, 2007; ADA, 

2010). Further, 12 states have implemented mandatory dental mercury discharge reduction 

programs that require amalgam separators and BMPs. For dental offices that have not yet 

installed amalgam separators, EPA estimates that this is a low-cost technology with an 

approximate average annual cost of $700 per office (U.S. EPA, 2011b). Opportunistic removal 

of concentrated sources of mercury through low-cost amalgam separators at dental offices is a 

common sense solution to managing mercury at the point in the waste stream where it is most 

concentrated, and from where the mercury would otherwise be released to air, land, and water. 

EPA is also proposing to amend selected parts of the General Pretreatment Regulations 

(40 CFR 403) in order to streamline permitting and oversight requirements specific to the dental 

sector. When categorical pretreatment standards apply to an industry, certain oversight 

requirements are created. As defined in 40 CFR 403, facilities that are subject to categorical 

pretreatment standards are referred to as Categorical Industrial Users (CIUs). The number of 

dental offices that would likely be subject to national pretreatment standards is approximately ten 

times the current number of CIUs. The proposed changes to 40 CFR 403 reflect EPA’s 

recognition that the current regulatory framework needs to be adjusted for the effective 

implementation and enforcement of these pretreatment requirements on the dental industry. 

Therefore, EPA is proposing a new classification of CIU, specifically tailored to the proposed 

rule: Dental Industrial User (DIU). EPA is proposing that DIUs not be subject to the oversight 

4 This document uses the general term “offices” to refer to any dentistry practice or facility that places or removes 

dental amalgam containing mercury.

2-2 

 
Section 2 - Summary and Scope

requirements for Significant Industrial Users (i.e., control mechanism issuance requirement,

annual inspection, and sampling requirements). Rather, EPA is proposing to allow Control 

Authorities to focus their oversight efforts on dental offices that fail to meet the compliance 

requirements of the DIU. 

2.2 APPLICABILITY OF THE PROPOSED RULE

EPA has not identified dental offices discharging amalgam waste directly to waters of the 

United States. Because EPA has very limited information on any direct discharge of dental 

amalgam, EPA is not proposing effluent limitation guidelines and new source performance 

standards for direct dischargers at this time. 

The proposed pretreatment standards apply to wastewater discharges to POTWs from 

offices where dentistry is performed, including institutions, permanent or temporary offices, 

clinics, mobile units, home offices, and facilities, including dental facilities owned and operated 

by federal, state, or local governments. EPA is not proposing to include wastewater discharges 

from dental offices specializing exclusively in 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 Section 4.2, these specialty practices do not 

place (restore) or remove dental amalgam, and thus EPA does not expect these offices to have 

any discharges of dental amalgam.

2.3 SUBCATEGORIZATION

In developing effluent limitation guidelines and pretreatment standards, EPA may divide 

an industry category into groupings called subcategories to provide a method for addressing 

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). Regulation of a category by subcategories provides that each subcategory has a uniform 

set of effluent limitations or pretreatment standards that takes into account technological 

achievability, economic impacts, and non-water-quality environmental impacts unique to that 

subcategory. 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. The CWA also authorizes EPA to take into account other factors that the 

Administrator deems appropriate. 

In developing the proposed rule, EPA considered whether subcategorizing the dental 

industry was warranted. EPA evaluated a number of factors and potential subcategorization 

approaches, including the size of the dental office, specialty practices, and unusual 

configurations that may be found at very large practices such as dental clinics and universities. 

EPA proposes that establishing formal subcategories is not appropriate for the Dental Category 

for three reasons. First, the proposed rule is structured to set standards only for those facilities 

that discharge dental amalgam. Second, the requirements do not include a size threshold because 

the technology is readily scaled to the size of the dental office. Finally, those states and localities 

2-3 
Section 2 - Summary and Scope

that already have regulatory programs for controlling discharges of dental amalgam have been 

largely successful without subcategorization.

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.

ISO. 2008. International Organization for Standardization. ISO 11143:2008 Dentistry - 

Amalgam Separators Standard. July. DCN DA00138. 

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. 1982. Fate of Priority Pollutants in Publicly Owned Treatment Works. EPA-440-1-

82-303. September. DCN DA00244. 

U.S. EPA. 2011a. EPA Analysis: Part 441 Option Cost Calculations. MS ExcelTM file. Office of 

Water. Washington, DC. DCN DA00146. 

U.S. EPA. 2011b. Economic Analysis for the Dental Amalgam Rule. MS ExcelTM file. Office of 

Water. Washington, DC. DCN DA00145. 

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. 

2-4 
Section 3 - Data Collection Activities

SECTION 3

DATA COLLECTION ACTIVITIES 

EPA collected data from a variety of sources for the proposed Dental Amalgam Rule, 

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 section includes a description of each data source; Section 4

through Section 14 of this document includes 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. EPA also conducted a POTW pass-through analysis on mercury for the industry. 

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 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.

3-1 
Section 3 - Data Collection Activities

3.3 MEETINGS WITH STAKEHOLDERS

EPA participated in several meetings with stakeholders including the Environmental 

Council of the States, environmental organizations, the American Dental Association (ADA), 

and the National Association of Clean Water Agencies (NACWA). Sections 3.3.1 through 3.3.4

summarize information collected during these meetings. 

3.3.1 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 

compliance reporting and monitoring. QSC also provided EPA with information on efficiency 

standards for amalgam separators (ECOS, 2010). 

3.3.2 Environmental Organizations 

EPA met with a coalition of environmental organizations, led by The Environmental Law 

and Policy Center and the National Resources Defense Council. Meetings between EPA and the 

coalition of environmental organizations focused on identifying the environmental impacts of 

dental amalgam discharges. In spring 2011, the coalition submitted a letter listing its suggested 

BMPs for the proposed Dental Amalgam Rule (Wu, 2011). 

3.3.3 American Dental Association (ADA)

EPA met with ADA in 2010 and 2011. ADA submitted data to EPA on their recently 

adopted principles for addressing mercury discharges from dental offices, the number of 

specialty offices in the industry, the geographic distribution of dental offices, financial 

characteristics of the industry, and operating characteristics of the industry (ADA, 2010).

3.3.4 National Association of Clean Water Agencies (NACWA) 

EPA met with NACWA in 2010 and 2011 to discuss the impact of pretreatment standards 

on POTWs. NACWA provided EPA information on its members’ experiences with handling 

mercury wastes from dental offices, implementing pretreatment programs for dental offices, and 

implementing pretreatment standards for industries with similar characteristics as the dental 

industry. 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 (U.S. EPA, 2011). 

3.4 AMALGAM SEPARATOR MANUFACTURERS (VENDOR CONTACTS) 

EPA met with, or participated in calls with, representatives of multiple amalgam 

separator manufacturers (ERG, 2010; ERG and Air Techniques, 2011; ERG and American 

Dental Accessories, 2011; ERG and DRNA, 2011; ERG and Rebec Solutions, 2011; ERG and 

SolmeteX, 2011). The purpose of the meetings was to gather information on the following 

issues:

3-2 
Section 3 - Data Collection Activities

• 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; 

• Amalgam disposal; and

• Installation trends.

3.5 AIR FORCE STUDY

In anticipation of the proposed Dental Amalgam Rule, 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 ISO 11143 certified, 

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. 

3.6 REFERENCES

ADA. 2010. ADA Principles to be Used to Develop Mandatory Separator Pretreatment Rule. 

Washington, DC. October 29. Document Control Number (DCN) DA00137. 

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. 

3-3 
Section 3 - Data Collection Activities

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. 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. 

ERG and SolmeteX. 2011. Notes from telephone conversation between Kimberly Landick, ERG, 

and SolmeteX, March 2, 2011: Subject Amalgam Separator Questions. DCN DA00064. 

U.S. Air Force. 2011. Synopsis of Dental Amalgam Separators (Project #10-017). Dental 

Evaluation and Consultation Service. February. DCN DA00079. 

U.S. EPA. 2008. Health Services Industry Detailed Study: Dental Amalgam. EPA-821-R-08-014. 

Washington, DC. August. DCN DA00057.

U.S. EPA, 2011. Information Collection Request: National Pretreatment Program. OMB 

Control No. 2040-0009, EPA ICR No. 0002.14 (Draft). Office of Wastewater

Management. March. DCN DA00144. 

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. 

3-4 
Section 4 - Profile of Dental Industry

SECTION 4

PROFILE OF DENTAL INDUSTRY

The industry category that would be affected by the proposed rule is Offices of Dentists 

(NAICS5

 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)6 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 (Census, 2007a): 

“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 2007 Economic 

Census, which reported that there were 127,057 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 Section 10

of this document. 

In addition to dental offices, dentistry can be performed at larger institutional dental 

service facilities (e.g., clinics or dental schools). These facilities are not included in the 2007 

Economic Census data. EPA estimates that in addition to the 127,057 dental offices identified 

from the Economic Census, there are 130 dental institutional facilities for a total of 127,187 

dental offices/facilities. EPA recognizes that additional dental practices also exist at installations 

operated by the federal government, specifically the Department of Defense. While EPA intends 

5 North American Industry Classification System. 

6 The DMR data are from EPA’s Integrated Compliance Information System-National Pollutant Discharge 

Elimination System (ICIS-NPDES) database.

4-1 

 
Section 4 - Profile of Dental Industry

such facilities to be subject to the proposed rule, EPA does not have information on which to 

base an estimate of the number of such facilities. 

Table 4-1. Number of Dental Offices by State (2007)

State NAICS 621210: Dental Offices

Alabama 1,451

Alaska 318

Arizona 2,529

Arkansas 956

California 19,973

Colorado 2,474

Connecticut 1,766

Delaware 237

District of Columbia 323

Florida 7,116

Georgia 3,231

Hawaii 689

Idaho 717

Illinois 5,768

Indiana 2,328

Iowa 1,073

Kansas 1,033

Kentucky 1,586

Louisiana 1,523

Maine 479

Maryland 2,563

Massachusetts 3,107

Michigan 4,400

Minnesota 2,037

Mississippi 870

Missouri 2,153

Montana 424

Nebraska 790

Nevada 1,033

New Hampshire 585

New Jersey 4,627

New Mexico 620

New York 9,101

North Carolina 2,885

North Dakota 259

Ohio 4,406

Oklahoma 1,376

4-2 
Section 4 - Profile of Dental Industry

Table 4-1. Number of Dental Offices by State (2007)

State NAICS 621210: Dental Offices

Oregon 1,871

Pennsylvania 5,285

Rhode Island 409

South Carolina 1,421

South Dakota 277

Tennessee 2,170

Texas 7,959

Utah 1,491

Vermont 272

Virginia 2,948

Washington 3,281

West Virginia 566

Wisconsin 2,078

Wyoming 223

Total U.S. 127,057

 Source: Census, 2007b. 

Table 4-2. Growth in Number of Dental Offices (1997 to 2007) 

NAICS Code SIC Code

Number of 

Offices in 

1997

Number of 

Offices in 

2002

Number of 

Offices in 2005

Number of 

Offices in 2007 

621210: Offices 

of Dentists

8021: Offices and 

Clinics of Dentists

114,178 118,305 122,918 127,057

Sources: Johnston, 2005; Census, 2007c and 2007d. 

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.

4-3 
Section 4 - Profile of Dental Industry

• 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).

• 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 offices to place or remove amalgam. EPA is not 

proposing to include wastewater discharges from dental offices where the practice does not 

typically place or remove dental amalgam. 

EPA does not have information on the number of practices that fall within each of the 

nine areas identified above. Rather, EPA used ADA’s 2009 Survey of Dental Practice to identify 

the number of dental practices that are general practices or specialty practices. Based on the 

information provided by ADA, EPA estimates that nationally, 21 percent of the total number of 

dental offices (127,187) are categorized as specialty practices (ADA, 2010). EPA estimates that 

65 percent of all specialty practices would fall within one of the areas that EPA is proposing not 

to subject to the proposed rulemaking (Vandeven and McGuiness, 2005). Therefore, EPA 

estimates that approximately 110,000 dental offices would be subject to the proposed 

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 

4-4 
Section 4 - Profile of Dental Industry

required to do so. Based on information contained in the 2009 DMR database, EPA identified 

five dental offices that have National Pollutant Discharge Elimination System (NPDES) permits. 

The dental offices were classified as minor dischargers. Of these, only one office reported 

discharge information in ICIS-NPDES. Table 4-4 summarizes the discharges reported by this 

office. 

Table 4-3. Dental Offices with NPDES Permits in ICIS-NPDES

NAICS NPDES ID SIC Code Office Name Location

621210: Dental Offices LAG531791 8021 Dr. Pellegrini DDS Madisonville, LA

LAG531821 8021 Medical/Dental Office Building Mandeville, LA

LAG532300 8021 Johnny J. Bouzigard DDS Cut Off, LA

LAG532353 8021 Bayou Dental Care Raceland, LA

MS0056901 8021 Southern Training & Education Starkville, MS

Source: U.S. EPA, 2009. 

Table 4-4. Dental Offices with Discharge Data in ICIS-NPDES

NAICS NPDES ID

Discharge 

(Outfall) Pollutant

Average 

Concentration

(mg/L)

Maximum 

Concentration 

(mg/L)

Pollutant 

Discharge 

(LBY)

Total 

Wastewater 

Flow 

(MGD)

621210: 

Dental 

Offices

MS0056901 001 Biochemical 

Oxygen 

Demand 

(BOD5)

134 134 244.92 0.0006

001 Chlorine, 

total residual

0 0 0 0.0006

001 Coliform, 

fecal general

1720 1720 3143.74 0.0006

001 Total 

Suspended 

Solids

37 37 67.63 0.0006

Source: U.S. EPA, 2009. 

LBY – pounds per year

MGD – million gallons per day

mg/L – milligrams per liter

The lack of information in TRI and DMR about dental industry wastewater discharges 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. 2010. 2009 Survey of Dental Practice: Income from the Private Practice of Dentistry. 

Document Control Number (DCN) DA00141. 

4-5 
Section 4 - Profile of Dental Industry

ADA. 2011. Definitions of Special Areas of Dental Practice. http://www.ada.org/2555.aspx#top

DCN DA00044. 

Census. 2007a. U.S. Census Bureau. Bridge Between NAICS and SIC Health Care and Social 

Assistance – Offices of Dentists. 2007 Economic Census. DCN DA00186.

Census. 2007b. Industry Quick Report: Offices of Dentists and Dental Laboratories. 2007 

Economic Census. DCN DA00048.

Census. 2007c. Sector 62: Health Care and Social Assistance: Geographic Area Series: Summary 

Statistics: 2007. 2007 Economic Census. Subject Series. EC0762A1. DCN DA00046.

Census. 2007d. Sector 31: Manufacturing: Industry Series: Detailed Statistics by Industry for the 

United States: 2007. 2007 Economic Census. Subject Series. EC0731I1. DCN DA00047.

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. EPA. 2008. Health Services Industry Detailed Study: Dental Amalgam. EPA-821-R-08-014. 

Washington, DC. August. DCN DA00057. 

U.S. EPA. 2009. Discharge Monitoring Report Loads Database. DMRLoads2009_v01. DCN 

DA00058. 

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. 

4-6 
Section 5 - Dental Amalgam Waste, Pollutants of Concern, and POTW Pass Through

SECTION 5

DENTAL AMALGAM WASTE, POLLUTANTS OF CONCERN, 

AND POTW PASS THROUGH 

This section discusses the sources of amalgam waste from dental offices and describes a 

typical office configuration. This section 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

Amalgam used in dental offices is 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, Sn8Hg) 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 use is diminishing in the United States. Due to the increased concern 

regarding mercury in the environment, several U.S. industries have significantly decreased their 

use of mercury since the 1980s (Vandeven and McGinnis, 2005). Although dental practices have 

also reduced their mercury amalgam use, as of 2005, amalgam was still widely used for 

restorations (Vandeven and McGinnis, 2005; Stone, 2004). ADA predicts that use of amalgam 

will continue to decrease due to factors such as the introduction of improved filling material, 

decreasing tooth decay rates, and earlier detection of tooth decay (U.S. EPA, 2007).

5.2 DENTAL 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 

5-1 
Section 5 - Dental Amalgam Waste, Pollutants of Concern, and POTW Pass Through

air/water separator portion of the vacuum system. Figure 5-1 displays 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). 

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

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. 

5-2 
Section 5 - Dental Amalgam Waste, Pollutants of Concern, and POTW Pass Through

5.3 POLLUTANTS OF CONCERN AND PASS THROUGH 

As described above, dental amalgam is usually composed of mercury, silver, tin, copper, 

zinc and small amounts of indium, and palladium. Of the dental amalgam constituents, mercury 

is of greatest concern to human health because it is a persistent, toxic chemical that can 

bioaccumulate across each trophic level of the food chain. Mercury from dental amalgam makes 

its way into the environment when it is discharged from the dental facility to a POTW, where it 

settles into sewage sludge, or is discharged to surface waters. Once discharged, certain 

microorganisms change mercury into methylmercury, a form of mercury that can be absorbed by 

fish, shellfish and animals that eat fish. 

EPA finds that the separation technologies considered for controlling mercury from 

amalgam solids will be similarly effective on the other solid metals composing amalgam. 

Therefore, controls installed for the reduction of mercury discharges will similarly reduce the 

discharge of other metals contained in amalgam. 

5.3.1 POTW Pass Through Analysis

To establish pretreatment standards, EPA examines whether the pollutants discharged by 

the industry “pass through” a POTW to waters of the U.S. or interfere with the POTW operation 

or sludge disposal practices. EPA’s consideration of pass through for national technology-based 

categorical pretreatment standards differs from that described in Section III of the general 

pretreatment standards. 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. 

Generally, in determining whether pollutants pass through a POTW, EPA compares the 

percentage of the pollutant removed by typical POTWs achieving secondary treatment with the 

percentage of the pollutant removed by facilities meeting BAT7

 effluent limitations. A pollutant 

is deemed to pass through a POTW when the average percentage removed by a typical POTW is 

less than the percentage removed by direct dischargers complying with BPT8

/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 proposed Dental Amalgam Rule, where only pretreatment standards are 

being developed, EPA compared the POTW removals with removals achieved by indirect 

dischargers using the candidate 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 (U.S. EPA, 1982). The 50 POTW 

study presents data on the performance of 50 POTWs performing secondary treatment to remove 

toxic pollutants. Results of this study demonstrated that POTWs remove 90 percent of total 

mercury found in wastewater. EPA received data from targeted studies performed by NACWA 

that indicate a POTW can remove 95 percent of total mercury (NACWA, 2007). However, these 

7 Best Available Technology Economically Achievable.

8 Best Practicable Control Technology Currently Available.

5-3 

 
Section 5 - Dental Amalgam Waste, Pollutants of Concern, and POTW Pass Through

studies reflect the performance of best performing POTWs, as opposed to the 50 POTW Study, 

which reflects nationwide POTWs. Consequently, for the proposed Dental Amalgam Rule, EPA 

maintains a POTW removal rate of 90 percent for its nationwide pass-through analysis. In 

comparison, indirect dischargers using the proposed technology will remove 99.0 percent or 

more of total mercury prior to discharge. Therefore, EPA concludes mercury passes through, and 

is proposing requirements to control its discharge. 

For the other metal constituents9

, POTWs remove the following percentages from 

wastewater prior to discharge (U.S. EPA, 1982):

• 88 percent of total silver;

• 79 percent of total tin;

• 84 percent of total copper; and 

• 79 percent of total zinc.

EPA concludes that these metals contained in dental amalgam, also pass through POTWs 

as defined above. 

5.4 REFERENCES

American Dental Accessories. 2010. Tech Tips #24: Amalgam Separators. The Right Amalgam 

Separator for You. Minneapolis, MN. July 28. 

http://www.amerdental.com/blog/general/tech-tips-24/. Document Control Number 

(DCN) DA00159. 

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=11184&catID=46. DCN DA00053.

Dental Equipment & Repair. 2008. Amalgam Separator.

http://dentalequipmentandrepair.com/id122.html. DCN DA00054.

Dube, Al. 2010. SolmeteX. 12th Annual EPA New England Pretreatment Coordinators 

Workshop, Amalgam Separator Inspection. October 13-14. DCN DA00056. 

Flight Dental Systems. 2006. Operatory Systems > A3 Operatory System. DCN DA00065. 

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.

NACWA (National Association of Clean Water Agencies). 2007. An Examination of Mercury 

Levels at Clean Water Agencies 2003-2006. December 18. DCN DA00108. 

9 EPA does not have information from the 50 POTW Study to estimate the POTW removals for indium and 

palladium.

5-4 

 
Section 5 - Dental Amalgam Waste, Pollutants of Concern, and POTW Pass Through

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. September. DCN DA00244. 

U.S. EPA. 2007. State Mercury Medical/Dental Waste Programs. DCN DA00189.

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. DCN DA00199.

5-5 
Section 6 - Current National, State, and Local Dental Mercury Reduction Programs

SECTION 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 MOU between EPA, the 

American Dental Association (ADA), and the National Association of Clean Water Agencies 

(NACWA) (see Section 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 19 local mandatory 

programs spanning six states. This section includes the following subsections: 

• Section 6.1 discusses national programs. 

• Section 6.2 summarizes state programs. 

• Section 6.3 summarizes local programs. 

• Section 6.4 presents voluntary programs.

6.1 NATIONAL DENTAL AMALGAM REQUIREMENTS AND GUIDANCE

Federal agencies that have established regulations for dental amalgam include the 

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

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

employee and consumer exposure and do not address wastewater discharges to POTWs. In the 

past, EPA has issued guidance and other strategies to reduce releases of mercury to the 

environment, including discharges of dental amalgam. 

6.1.1 U.S. EPA Strategies to Reduce Mercury Discharges

Before developing the proposed pretreatment standards, EPA and 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 mercuryassociated 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 Binational Toxics Strategy, created a Mercury Workgroup that promoted activities to 

reduce mercury releases to the Great Lakes Basin. This Workgroup included 

representative states, environmental organizations, and the Council of Great Lakes 

Industries. The Workgroup’s review of mercury releases in the Great Lakes area 

6-1 
Section 6 - Current National, State, and Local Dental Mercury Reduction Programs

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). 

EPA regulates the disposal of mercury-containing waste under the Resource 

Conservation and Recovery Act (RCRA). A mercury-containing waste can be considered 

hazardous in two ways: (1) as a listed waste; or (2) as a characteristic waste.10 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 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 how much 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 1 kilogram of acute hazardous waste per month.

11 Such facilities are 

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

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

managed properly. However, some states have additional requirements for CESQGs or do not 

exempt CESQGs from all requirements (HERCenter, 2008).

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). 

10 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. 11 Elemental mercury found in dental amalgam is a non-acute hazardous waste.

6-2 

 
Section 6 - Current National, State, and Local Dental Mercury Reduction Programs

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). 

6.1.4 American Dental Association 

The American Dental Association (ADA) has developed several programs to reduce 

dental mercury being discharged from dental offices. Programs include development of best 

management practices, list of nine principles, and creation of an amalgam recovery program. 

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-defined 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 

management and disposal of amalgam waste. These include information regarding proper 

recycling 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.

6-3 
Section 6 - Current National, State, and Local Dental Mercury Reduction Programs

Table 6-1. ADA BMPs for Dental Amalgam

Focus Best Management Practice

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.

Noncontact 

amalgam

Salvage, store, and recycle non-contact amalgam.

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

bags), or regular garbage.

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

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.

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): 

6-4 
Section 6 - Current National, State, and Local Dental Mercury Reduction Programs

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; 

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.

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). 

6.2 STATE DENTAL AMALGAM REQUIREMENTS 

EPA identified 12 states as having mandatory program requirements for dental offices: 

• Connecticut; 

6-5 
Section 6 - Current National, State, and Local Dental Mercury Reduction Programs

• Louisiana12; 

• Maine; 

• Massachusetts; 

• Michigan; 

• New Hampshire; 

• New Jersey; 

• New York; 

• Oregon; 

• Rhode Island; 

• Vermont; and 

• Washington. 

In addition to the above states, New Mexico passed a bill in 2013 that creates the Dental 

Amalgam Waste Reduction Act. The Act requires dental offices to remove dental amalgam from 

waste streams by installing an amalgam separator by December 31, 2014 that complies with 

international standards for removal efficiency (New Mexico Legislature, 2013). 

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, NY, OR, VT, WA, and only new 

offices in RI). 

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

Do not use bulk mercury (LA, NJ, NY, OR).

Amalgam separator 

technology 

specifications

Meet ISO Standard 11143 (CT, ME, MI, NH, NJ, NY, OR, RI, VT, WA).

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

a

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

Operate at 99% efficiency (NY if new, RI).

Operation 

specifications for 

amalgam separators

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

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

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

Method for 

demonstrating 

compliance

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

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

Maintain maintenance and servicing records and be able to provide upon request (CT, ME).

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

12 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.

6-6 

 
Section 6 - Current National, State, and Local Dental Mercury Reduction Programs

Table 6-2. Summary of Elements of State Requirements

Element Examples from State Requirements

Compliance tracking Department of Environmental Protection (DEP) inspections (CT).

Web form for providing proof of compliance (RI).

Sources: CTDEP, 2006; Louisiana Legislature, 2006; MassDEP, 2007; Maine DEP, 2005; MIDEQ, 2008; NHDES, 

2002; NYDEC, 2007; Oregon State Legislature, 2007; RIDEM, 2007; VTDEC, 2006; WADOE, 2005; Walsh, 2007.

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. 

Bills for dental mercury controls have been proposed but not passed in the following 

states:

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

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

and HB 665, Bill to Require Dentists to Provide Information about Mercury or 

Mercury Amalgam to Patients. It appears that both of these bills failed to clear the 

House and were tabled in the House Health Committee (ALISON, 2007). 

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

Department of Environmental Quality to develop a plan for reducing mercury 

pollution from dental procedures and to implement a mandatory program for dental 

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

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

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

amalgam in dental and related services, passed the state Senate by a vote of 51 to 28 

but was vetoed by the governor’s office (California Legislative Counsel, 2005). 

Three states (Florida, Idaho, and Minnesota) 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.

6-7 
Section 6 - Current National, State, and Local Dental Mercury Reduction Programs

6-8 

Table 6-3. Mandatory BMPs by State and Comparison to ADA BMPs a,b

Best Management Practice ADA CT LA MA NH NJ NY OR RI VT WA

Requirement/Guidance G R R R R R R R R R R

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 X

Recycle used disposable amalgam capsules. 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

Salvage, store and recycle non-contact amalgam (scrap 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

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

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 X

Where appropriate, disposable amalgam traps are preferable to reusable traps. X 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 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
Section 6 - Current National, State, and Local Dental Mercury Reduction Programs

6-9 

Table 6-3. Mandatory BMPs by State and Comparison to ADA BMPs a,b

Best Management Practice ADA CT LA MA NH NJ NY OR RI VT WA

Requirement/Guidance G R R R R R R R R R R

Amalgam Separators

Install and use amalgam separators. 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; NHDES, 2002; NJR, 2007; NYDEC, 2007; RIDEM, 2007; 

VTDEC, 2006; and WADOE, 2005. 

G — Guidance.

R — Requirement.

a — Michigan’s Best Management Practices are not available online; Michigan’s law requires that on or before December 31, 2013, dentists must install and use 

an amalgam separator on each wastewater drain in the dentist's office that is used to discharge dental amalgam. The amalgam separator must have an efficiency 

of 95 percent or greater as determined through testing in accordance with ISO 11143 standards (MIDEQ, 2008). Maine requires the installation and use of 

amalgam separators but does not require that dental offices follow the state’s Best Management Practices (Maine DEP, 2005). 

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). 
Section 6 - Current National, State, and Local Dental Mercury Reduction Programs

6-10 

Table 6-4. Voluntary BMPs by State and Comparison to ADA BMPs

Best Management Practice ADA DC FL ID MN

Initial Use

Use only pre-capsulated alloys and/or stock a variety of capsule sizes. X X X X

Do not use bulk mercury. X X X X

Recycling/Disposal

Manage amalgam waste through recycling as much as possible. 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

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

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

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

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

Chair-Side Traps

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

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

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

Vacuum Pumps

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

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

Amalgam Separators

Install and use amalgam separators. 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

Sources: ADA, 2007; District of Columbia Water and Sewer Authority, 2012; FLDEP, 2001; ISDA, 2008; MDA, 2003.
Section 6 - Current National, State, and Local Dental Mercury Reduction Programs

6.3 LOCAL DENTAL AMALGAM REQUIREMENTS 

EPA identified and reviewed nine mandatory program requirements for the following 

localities:

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

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

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

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

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

Oshkosh, GrandChute and Menasha West, Wausau, Fond du Lac and Green Bay-De 

Pere, Waukesha, Watertown, Beloit, and La Crosse (Behm, 2008); 

• Fort Collins and Boulder, CO; 

• San Francisco, CA; 

• Solon, OH; and 

• Narragansett Bay, RI. 

This list is not intended to be an exhaustive list of local programs. Table 6-5 summarizes 

the elements of the local requirements to control discharges of dental mercury. Table 6-6

compares the lists of local BMPs to ADA’s BMPs. Many elements included in the local 

requirements are similar to those of the state requirements described in Section 6.2. 

Table 6-5. Summary of Elements of Local Requirements

Element Examples from Local Requirements

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

installed.

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

Francisco, Solon, Narragansett Bay).

Alternative to installing an amalgam separator:

− Office must pay a fee of $1,770 per year and be subject to inspections and 

testing (East Bay). 

− Office must obtain a discharge permit and monitor wastewater (San Francisco).

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

Narragansett Bay).

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

Certain specialty fields (King County).

Offices that installed separators prior to regulation (Palo Alto).

Technology specifications Meet ISO Standard 11143 (King County, Madison, East Bay).

Method for demonstrating 

compliance

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

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

Madison, Milwaukee).

Provide documentation of mercury waste hauling (East Bay, Palo Alto, NE Ohio).

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

penalties for noncompliance (King County).

Inspections performed by local POTW (East Bay, Palo Alto, Madison, Milwaukee).

Sources: EBMUD, 2005; KCWTD, 2007; MMSD, 2008; NEORSD, 2007; Palo Alto, 2007; Walsh, 2007. 

6-11 
6-12 

Section 6 - Current National, State, and Local Dental Mercury Reduction Programs

Table 6-6. Best Management Practices by Municipality

Best Management Practice

Municipality

ADA

East Bay, 

Oakland, 

CA

King 

County, 

WA

Milwaukee and 

Madison, WI a 

Narragansett 

Bay, RI

NE Ohio, 

Cleveland, 

OH

Palo 

Alto, 

CA

Requirement/Guidance G R R R R R R

Initial Use

Use only pre-capsulated alloys and/or stock a variety of capsule sizes. X X X X X X

Do not use bulk mercury. X X X X

Recycling/Disposal

Manage amalgam waste by recycling as much as possible. X X X X X

Recycle used disposable amalgam capsules. X X X X

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

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

Recycle extracted 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 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

Do not put contact amalgam waste in biohazard containers, infectious 

waste containers (red bags), or regular garbage. 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 

Chair-Side Traps

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

Where appropriate, disposable amalgam traps are preferable to 

reusable traps. X X (G) X (G)
6-13 

Section 6 - Current National, State, and Local Dental Mercury Reduction Programs

Table 6-6. Best Management Practices by Municipality

Best Management Practice

Municipality

ADA

East Bay, 

Oakland, 

CA

King 

County, 

WA

Milwaukee and 

Madison, WI a 

Narragansett 

Bay, RI

NE Ohio, 

Cleveland, 

OH

Palo 

Alto, 

CA

Requirement/Guidance G R R R R R R

Vacuum Pumps

Recycle contents retained by the vacuum pump filter or other 

amalgam collection device, if they contain amalgam. 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

Use line cleaners that minimize the dissolution of amalgam. X X X X (G) X

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

lines. X X X X X (G) 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

Install and use amalgam separators. X X X X X X X

Sources: ADA, 2007; EBMUD, 2005; KCWTD, 2007; NEORSD, 2007; Palo Alto, 2007; Uva, 2007; MMSD and University of Wisconsin Extension. 2006. 

a — The Milwaukee and Madison programs reference BMPs developed by the Wisconsin Dental Association (MMSD and University of Wisconsin Extension. 

2006).

G — Guidance.

R — Requirement.
Section 6 - Current National, State, and Local Dental Mercury Reduction Programs

6.4 VOLUNTARY PROGRAMS

Some states and localities have initiated voluntary rather than mandatory dental mercury 

reduction programs. The following two subsections 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 6-7 summarizes the voluntary programs and presents the 

participation rates for the programs. This table also contains some state voluntary program 

participation rates for comparison purposes.

6.4.1 Voluntary Programs with High Participation Rates

This subsection describes case studies of three voluntary programs (Duluth, MN; 

Wichita, KS; 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 

6-14 
Section 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 Mercury Code of 

Management Practices (CMP) for the city. The CMP 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 Mercury CMP 

Program without a mandatory separator requirement (Walsh, 2007). 

Massachusetts 

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

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

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

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

install and use amalgam separators. The program’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 Section 6.2, 

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). 

6-15 
Section 6 - Current National, State, and Local Dental Mercury Reduction Programs

6-16 

Table 6-7. Summary of Voluntary Programs for Reducing Dental Amalgam Releases to Wastewater

State (Jurisdiction) Date Description Participation Rate Verification of Participation

California

(Palo Alto, San 

Francisco, and 

Central Contra 

Costa)

No 

information

Voluntary installation of amalgam separators and 

implementation of BMPs.

65% Survey conducted by sanitation 

districts in 2000.

Kansas 

(City of Wichita)

April 2000 Developed a Mercury Code of Management Practices 

(CMP).

Encouraged dentists to use technologies beyond chairside 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.
Section 6 - Current National, State, and Local Dental Mercury Reduction Programs

6-17 

Table 6-7. Summary of Voluntary Programs for Reducing Dental Amalgam Releases to Wastewater

State (Jurisdiction) Date Description Participation Rate Verification of Participation

Missouri 

(Springfield)

2006 University of Missouri conducted a study to 

determine whether voluntary BMPs could 

significantly reduce mercury discharges from dental 

offices.

Offered a half-day training course on BMPs.

Also sent outreach materials via mail to local 

members of the dental society.

Collected wastewater samples to determine mercury 

reductions. 

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 amalgam, proper use of chairside 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 mailaway firms to obtain lists of 

dental office customers.

Wisconsin

(Madison)

1997 Encouraged use of amalgam separators through 

outreach to dentists.

Section 6.4.1 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.
Section 6 - Current National, State, and Local Dental Mercury Reduction Programs

6.4.2 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, one 

of the two programs discussed in this section decided to implement mandatory requirements for 

BMPs and amalgam separators due to the low level of participation in the voluntary program. 

Seattle and King County 

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

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

number of activities 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 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 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 scrap 

amalgam.

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

waste.

6-18 
Section 6 - Current National, State, and Local Dental Mercury Reduction Programs

• 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 6-7 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 section focuses on 

participation rates for the voluntary program. Section 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 

• A list of amalgam recyclers. 

MU Extension also sent training materials by mail to dentists who did not attend the 

course. 

6-19 
Section 6 - Current National, State, and Local Dental Mercury Reduction Programs

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 scrap amalgam increased significantly after BMP 

training while the improper disposal decreased. 

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

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

dental office staff and better labeling and instruction from medical waste management 

companies.

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

trap contents with regular waste decreased.

• More of the dentists who 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 Missouri/Springfield area did not use 

amalgam separators prior to outreach and did not install amalgam separators after MU conducted 

its outreach. MU concluded that very few dentists use amalgam separators because they are not 

required in Missouri or Springfield (MU Extension, 2007). 

6.4.3 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 will have higher participation rates than voluntary programs. However, over time (5 to 

6-20 
Section 6 - Current National, State, and Local Dental Mercury Reduction Programs

10 years), participation rates for well-implemented voluntary programs will be similar to 

participation rates for mandatory programs (Larry Walker Associates, 2002). 

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

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

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. Often, the mandatory second 

phase of the program was not ultimately implemented. 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. 

6.5 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 News. 2013. ADA Business Resources endorses HealthFirst's Amalgam Recovery 

Program. November 2. DCN DA00245. 

ADA Business Resources. 2014. HealthFirst Amalgam Recovery Program. Accessed 2014. DCN 

DA00246. 

ALISON (Alabama Legislative Information System Online). 2007. Regular Session 2004. DCN 

DA00210. 

Anderson, N. 2007. Statement of Norris Anderson, Ph.D., Director, Office of Science and Health 

Coordination, FDA. November 14. DCN DA00204. 

Arkansas. 2003. House Bill 1309: An Act to Reduce the Incidence of Mercury Poisoning in 

Arkansas, and for Other Purposes. State of Arkansas 84th General Assembly, Regular 

Session, 2003. DCN DA00187. 

Behm, D. 2008. Dentists Filtering Out Mercury but Nearly One-fifth Miss MMSD Deadline. 

Milwaukee Journal Sentinel. February 9. DCN DA00203. 

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. 

California Legislative Counsel. 2005. Complete Bill History, Bill Number: AB No. 966. 

http://www.leginfo.ca.gov/pub/05-06/bill/asm/ab_0951-

1000/ab_966_bill_20060929_history.html. DCN DA00211. 

6-21 
Section 6 - Current National, State, and Local Dental Mercury Reduction Programs

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. 

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. 

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. DCN DA00178. 

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. DCN DA00174. 

HERCenter (Healthcare Environmental Resource Center). 2008. Best Management Practices for

Common Dental Office Wastes. http://www.hercenter.org/dentistwastes.cfm. DCN 

DA00208. 

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. 

Maine Legislature. 2001. Chapter 16-B: Mercury-Added Products and Services Heading: PL 

1999, C. 779. Maine Revised Statues Title 28: Waters and Navigation.

http://www.mainelegislature.org/legis/statutes/38/title38sec1661-c.html. DCN DA00069. 

MassDEP (Massachusetts Department of Environmental Protection). 2007. Dental 

Amalgam/Mercury Recycling Program. DCN DA00191. 

6-22 
Section 6 - Current National, State, and Local Dental Mercury Reduction Programs

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. 

MIDEQ (Michigan Department of Environmental Quality). 2008. Dental Mercury Amalgam 

Separators, Public Act 503 of 2008. DCN DA00071. 

MMSD (Madison Metropolitan Sewerage District). 2008. MMSD Mercury Pollutant 

Minimization Program DCN DA00220. 

MMSD and University of Wisconsin Extension. 2006. Amalgam Management for Dental 

Offices. Milwaukee, WI. DCN DA00232.

MU Extension (University of Missouri Extension Environmental Assistance Center). 2007. 

Maximizing Voluntary Reductions in Dental Amalgam Mercury: Reduction in Mercury 

Discharges. EPA#E0000127. P1-98765101-0. November. DCN DA00223. 

MU Extension. 2011. P2: Dental Practices Managing Dental Amalgam. DCN DA00134. 

NEORSD (Northeast Ohio Regional Sewer District). 2007. Mercury Program: Annual Report 

Form for Dental Care Practices, 2006. DCN DA00213. 

New Mexico Legislature. 2013. Senate Bill 099: Dental Amalgam Waste Reduction.

http://www.nmlegis.gov/Sessions/13%20Regular/final/SB0099.pdf. DCN DA00241. 

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. DCN DA00222. 

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/2007R1/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.

Palo Alto (City of Palo Alto Regional Water Quality Control Plant). 2007. Advanced Mercury 

Source Control Study: 2006 Annual Report of Activity. February. DCN DA00182. 

RIDEM (Rhode Island Department of Environmental Management). 2007. Mercury in Dental 

Amalgam. http://www.dem.ri.gov/topics/mercury.htm. DCN DA00207. 

6-23 
Section 6 - Current National, State, and Local Dental Mercury Reduction Programs

U.S. EPA. 2005. POTW Mercury Control Strategy. May 9. DCN DA00180. 

Uva, T.P. 2007. Narragansett Bay Commission’s (NBC) Comments on EPA’s Preliminary 2008 

Effluent Guidelines Program Plan. December 27. DCN DA00237. 

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.ecy.wa.gov/mercury/mercury_dental_bmps.html. DCN DA00080. 

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. 

6-24 
Section 7 - Treatment Technologies and Best Management Practices (BMPs) 

SECTION 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 Section 5, chair-side 

traps and vacuum pumps 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. Finally, as described in Section 6, best 

management practices (BMPs) are integral to reducing pollutants in dental discharges. 

This section describes amalgam separators and polishing, including information on 

treatment efficiency. 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 (such as 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.13 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 dumping out the solid particles collected by them into a bucket or other storage container, 

then properly disposing of the dental amalgam waste (ERG and SolmeteX, 2011). 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, 

2007a). Virtually all amalgam separators currently on the market use sedimentation processes 

(with or without filtration) to settle out the solids from the wastewater. 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 (Fan et al., 2002). Baffles or tanks 

can reduce the speed of the wastewater flow, allowing more amalgam particles to settle out. 

13 Gravity-feed amalgam separators might also be installed at dental offices.

7-1 

 
Section 7 - Treatment Technologies and Best Management Practices (BMPs) 

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 

Section 7.2. 

Although none of the separators that EPA identified in the literature review added 

chemicals to enhance solids removal, chemical and polymer additions have been effective in 

precipitating a portion of dissolved mercury out of dental wastewater (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, 2011b). 

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 

mode without any noticeable effect on vacuum suction, it is vital that the unit be checked 

periodically, and serviced if necessary. Manufacturers will typically recommend the frequency of 

checks and service to ensure proper operation. 

7-2 
Section 7 - Treatment Technologies and Best Management Practices (BMPs) 

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 

Two standards are currently used to evaluate the treatment efficiency of amalgam 

separators: (1) International Organization for Standardization (ISO) Standard 11143; and (2) 

U.S. EPA’s Environmental Technologies Verification (ETV) program. 

ISO Standard 11143. The majority of amalgam separators currently on the market have 

been evaluated for their ability to meet ISO 11143, the international standard for amalgam 

separators used in connection with dental equipment. ISO 11143 calls for measuring amalgam 

separator efficiency by evaluating the retention of amalgam. 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. 

ISO Standard 11143 requires that an amalgam separator remove at least 95 percent by 

weight of amalgam particles (i.e., the 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): 

• 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 is important to note that certification under this standard is based not on total mercury 

concentration in effluent wastewater, but on particle removal. To test the efficiency of an 

amalgam separator, a slurry of water and amalgam is poured into the amalgam separator and 

effluent water is collected. This effluent wastewater is filtered through a series of pre-weighted 

filters, the filters are dried and weighed, and the final weight of the filters is then compared 

against the original weight (Batchu et al., 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 determine 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 

7-3 
Section 7 - Treatment Technologies and Best Management Practices (BMPs) 

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 (ETV) Standard. The EPA/ETV program 

has developed a standard more rigorous than ISO 11143. The EPA/ETV standard, “Protocol for 

the Verification of Hg Amalgam Removal Technologies,” uses a concentration-based criterion 

and measures efficiency as a function of mercury concentration as opposed to particulate 

removal (NSF 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 

(mm) and vacuum filter traps can capture particles as small as 0.4 mm (Fan et al., 2002). The 

combined removal rate of the 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 particulate mercury removal 

efficiencies for the three technologies ranged from 95 to 99.9 percent. However, the 

study also noted that an effluent concentration of 0.2 parts per million could not be 

consistently met without chemical treatment (Boston University, 1998). 

• A 2001 study found that amalgam separators were able to remove 91 to 99 percent of 

amalgam particles (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). 

7-4 
Section 7 - Treatment Technologies and Best Management Practices (BMPs) 

Table 7-1 provides a non-inclusive list of 39 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.14 As illustrated, all 

separators exceeded the ISO Standard of 95 percent efficiency, 34 separators exceeded 97 

percent efficiency, and 29 separators exceeded 99 percent efficiency of amalgam particle 

removal. The separators described in Table 7-1 achieved an average efficiency of 98.8 percent

and a median efficiency of 99.0 percent. 

Table 7-1. Efficiency and Technology of 39 Amalgam Separators 

Model Manufacturer Treatment Technology

Percentage of Amalgam 

Removed (by weight) a

Data 

Sources

A 1250 Air Techniques Centrifugation >99.0% 6

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 Boss Hygenitek Sedimentation, filtration, 

ion exchange

99.2% 1,9

Amalgam 

Collector CE18

R & D Services Sedimentation 99.6% 1,9

Amalgam 

Collector CE24

R & D Services Sedimentation >99.9% 1,10

Amalgam 

Collector CH12

R & D Services Sedimentation >99.9% 1,10

Amalgam 

Collector CH9

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

Catch 1000 Plus Rebec Solutions Sedimentation 99.0% 1,13

Catch 400 Plus Rebec Solutions Sedimentation 99.0% 1,13

Catch 9000 Plus Rebec Solutions Sedimentation 99.0% 1,13

ECO II Metasys, distributed by 

Pure Water 

Development

Sedimentation 97.5% 1,4,5,10

14 Mention of product and vendor names does not constitute an endorsement by EPA.

7-5 

 
Section 7 - Treatment Technologies and Best Management Practices (BMPs) 

Table 7-1. Efficiency and Technology of 39 Amalgam Separators 

Model Manufacturer Treatment Technology

Percentage of Amalgam 

Removed (by weight) a

Data 

Sources

Hg5 SolmeteX Sedimentation, filtration, 

chemical binding

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% 1,15

Merc II Bio-Sym Medical Sedimentation, filtration, 

ion exchange

98.2% 5,9

MRU10 Dental Recycling North 

America

Sedimentation, filtration, 

ion exchange

>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

MSS 2000 Maximum Separation 

Systems

Sedimentation, filtration 98.9% 2,4,5

MSS 601 Maximum Separation 

Systems

Sedimentation, filtration 95.0% 3,5

Rasch 890-1000 AB Dental Trends Sedimentation, filtration, 

ion exchange

98.9% 2,9

Rasch 890-1500 AB Dental Trends Sedimentation, filtration, 

ion exchange

98.0% 1,16,17

Rasch 890-4000 AB Dental Trends Sedimentation, filtration, 

ion exchange

>99.9% 2,4

Rasch 890-6000 AB Dental Trends Sedimentation, filtration, 

ion exchange

98.0% 1,16,17

Rasch 890-7000 AB Dental Trends Sedimentation, filtration, 

ion exchange

98.0% 1,16,17

Rasch AD-1500 American Dental 

Accessories

Sedimentation 95.0% 1,5

REM2000 

Series/Catch 

1000

Rebec Solutions Sedimentation 99.7% 1,13

REM2000 

Series/Catch 400

Rebec Solutions Sedimentation 99.6% 1,13

REM2000 

Series/Catch 

9000

Rebec Solutions Sedimentation 99.6% 2,13

Median 99.0%

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. 

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) – ERG and Air Techniques, 2011; (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, (15) MARS Bio Med Processes, 

2012; (16) Haraldsson and Nyman, 2001; (17) Haraldsson and Nyman, 2003.[Summary of analysis included in ERG, 2014].

7-6 
Section 7 - Treatment Technologies and Best Management Practices (BMPs) 

7.2 POLISHING

Mercury is both dissolved and suspended in dental amalgam. More than 99.6 percent is 

suspended (Stone, 2004). An additional process (sometimes referred to as polishing) uses ion 

exchange to remove dissolved mercury. In contrast to amalgam separators that contain an ion 

exchange component in the same unit (as discussed in the previous section), polishing 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 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 in order for the resin (or 

other capturing material) to capture the dissolved mercury. As a result, EPA concludes this 

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. 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, ISO certification testing is based on an evaluation of the removal of 

amalgam 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 to 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 facilities that were responding to sanitation district concerns over their mercury 

discharges. In both cases, the polishing systems were installed (as is usual) to treat wastewater 

after it left the amalgam separator. 

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 

not surprising since, as indicated above, dissolved mercury is 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 also found limited data on the costs of polishing systems (ERG, 2011a). 

7.3 BEST MANAGEMENT PRACTICES 

Most state and local dental mercury reduction programs include BMPs. Most are based 

on the American Dental Association’s BMPs developed in 2003 (ADA, 2007b), discussed in 

7-7 
Section 7 - Treatment Technologies and Best Management Practices (BMPs) 

6.1.4. After reviewing ADA’s BMPs and those of state and local programs, EPA decided to 

include certain operational, maintenance, and inspection practices in its proposed rule because 

these practices have a significant impact on how effectively amalgam separators function to 

achieve their certified performance levels. 

EPA proposes to require line cleaners that do not contain bleach and are of neutral pH. 

Bleach and other corrosive cleaners can solubilize bound mercury. If dental practices use 

corrosive cleaners to clean vacuum lines leading 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). 

EPA’s second proposed BMP prohibits the flushing of scrap amalgam (contact and noncontact) into drains that do not lead to an amalgam separator (e.g., a cuspidor not attached to the 

vacuum line), and into general use sinks. Sources of dental amalgam include, but are not limited 

to, chair-side traps, screens, vacuum pump filters, dental tools, or collection devices. This rule 

limits additional avenues through which mercury might be discharged from dental offices. 

7.4 REFERENCES

ADA (American Dental Association). 2007a. ADA Professional Product Review. Document 

Control Number (DCN) DA00043. 

ADA. 2007b. Best Management Practices for Amalgam Waste. Updated July 2007. DCN 

DA00165. 

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. DCN DA00215. 

Boston University. 1998. A New Prescription: Pollution Prevention Strategies for the Health 

Care Industry. October 7. DCN DA00170. 

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. DCN DA00226. 

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. DCN DA00024. 

7-8 
Section 7 - Treatment Technologies and Best Management Practices (BMPs) 

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 (revised 

memorandum). Chantilly, VA. May 23. DCN DA00122. 

ERG. 2011b. Dental Recycling North America, Inc. (DRNA) Meeting Minutes for 19 January 

2011. March 23. DCN DA00059. 

ERG. 2014. Amalgam Separator Treatment Efficiencies. MS ExcelTM file. September. DCN 

DA00233. 

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. 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. 

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 SolmeteX. 2011b. Notes from telephone conversation between Kimberly Landick, 

ERG and SolmeteX, March 2, 2011: Subject Amalgam Separator Questions. DCN 

DA00064. 

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. DCN DA00008. 

Garcia, A. 2009. EPA Audit Follow-Up Report. U.S. EPA Region 8. September 15. DCN 

DA00164. 

Haraldsson, C. and P. Nyman. 2003. Test of separation efficiency according to SS-EN ISO 

11143. SP Swedish National Testing and Research Institute. June 13. DCN DA000228. 

Haraldsson, C. and P. Nyman. 2001. Test of separation efficiency according to SS-EN ISO 

11143. SP Swedish National Testing and Research Institute. October 2. DCN DA00229.

7-9 
Section 7 - Treatment Technologies and Best Management Practices (BMPs) 

ISO (International Organization for Standardization). 2008. ISO 11143 Dentistry—Amalgam 

Separators, Second Edition. Geneva, Switzerland. DCN DA00138. 

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/MCESMDA%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. 

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. POTW Mercury Control Strategy. May 9. DCN DA00180. 

Vandeven, J., and S. McGinnis. 2004. Cost-Effectiveness of Removing Amalgam from Dental 

Wastewater. California Dental Association Journal 32(7):564-573. DCN DA00021. 

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. 

7-10 
Section 8 - Regulatory Options 

SECTION 8

REGULATORY OPTIONS 

EPA identified one technology that is available and has been demonstrated to control 

dental amalgam discharges from the Dental Category: amalgam separators. EPA further 

identified best management practices (BMPs) that would ensure the effectiveness of the 

technology and would further reduce discharges of dental amalgam not captured by an amalgam 

separator. 

8.1 PRETREATMENT STANDARDS FOR EXISTING SOURCES (PSES)

EPA developed one option based on proper operation and maintenance of amalgam 

separators that achieve a 99.0 percent reduction of amalgam from amalgam process wastewater,

15

along with BMPs. Dental offices can comply with the numeric pretreatment standard for existing 

sources (i.e., 99.0 percent reduction in amalgam discharges) by installation, proper operation, 

and proper maintenance of an amalgam separator certified to meet 99.0 percent reduction of total 

mercury according to the 2008 ISO 11143 standard. Compliance with two additional BMPs — 

not flushing scrap amalgam down the drain and cleaning of chair-side traps with non-bleach, 

non-chlorine cleaners — are necessary to prevent mercury discharges that would bypass the 

separator. Dental offices would also be able to meet the standard by certifying that they do not 

place or remove amalgam.

16

EPA finds that the proposed 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. The 

American Dental Association (ADA) recommends its dentists to use the technology on which the 

rule is based (i.e., amalgam separators and BMPs). Further, 40 percent of dental offices use 

amalgam separators on a voluntary basis or are in states with state or local laws requiring the use 

of amalgam separators. For those dental offices that have not yet installed an amalgam separator, 

EPA estimates that this is a low-cost technology with an approximate average annual cost of 

$700 per office17 (U.S. EPA, 2011). EPA’s economic analysis of these costs in relation to the 

overall income of the regulated entities show that this proposed rule is economically achievable 

(see Section 10). Finally, EPA also examined the non-water-quality environmental impacts of the 

proposed rule and found them to be acceptable (see Section 14). 

EPA is not proposing to establish pretreatment standards based on technologies that 

remove dissolved mercury, i.e., polishing. None of the states with mandated requirements to 

reduce dental mercury discharges requires polishing. EPA also lacks adequate performance data 

to assess the efficacy of polishing or its availability for nationwide use. EPA’s current 

information suggests that polishing only achieves incremental removals over the selected 

15 Amalgam process wastewater means any wastewater generated and discharged by a dental discharger through the 

practice of dentistry that may contain dental amalgam. 16 Dentists that elect to certify that they do not install or remove amalgam will be exempt from any further 

requirements of the proposed rule. See 40 CFR 441.10. EPA recognizes that dentists, infrequently, may remove 

amalgam in the course of emergency treatment. EPA does not intend for discharges of dental amalgam, related to 

only to these infrequent emergency treatments, to preclude such dentists from certifying.

17 This estimate reflects the average annualized cost for dentists that do not currently have amalgam separators. 

8-1 

 
Section 8 - Regulatory Options 

amalgam separator technology of less than one-half percent of total mercury (Garcia, 2009). 

While very small amounts of mercury can have environmental effects, EPA lacks sufficient 

evidence to assert that adding polishing technology to amalgam separation will result in mercury 

discharge reductions that have a discernible environmental impact greater than the reductions 

achieved by amalgam separation alone. EPA estimates that the capital costs of amalgam 

separators and polishing are at least 4 times that of amalgam separators alone (ERG, 2011). 

Finally, EPA is uncertain whether existing dental offices have adequate space to install polishing 

controls. These factors led EPA to find that polishing is not “available” as that term is used in the 

CWA. As a result, EPA did not select amalgam separators followed by polishing as the 

technology basis for the proposed rule. 

8.1.1 Requirements

The proposed rule would establish a pretreatment standard that would require removal of 

at least 99.0 percent of total mercury from amalgam discharges and require dental offices to 

follow BMPs. Affected dental offices would be able to meet the standard by using, properly 

operating, and maintaining a dental amalgam separator certified to achieve at least 99.0 percent 

reduction of total mercury according to the 2008 ISO 11143 standard, to perform certain BMPs, 

and to certify to this effect. Dental offices could also meet the standard by certifying that they do 

not install or remove amalgam except in limited emergency circumstances. As a point of 

clarification, dentists that elect to certify that they do not install or remove amalgam will be 

exempt from any further requirements of the proposed rule. 

While the proposed rule does not require the use of an amalgam separator to meet the 

numeric standard, EPA expects that most, if not all, dentists who place or remove amalgam 

would use this widely available technology to comply with the proposed numeric standard. EPA 

expects dentists will choose to install and operate an amalgam separator because of the nature of 

dental offices, the variability of the flows and resulting waste streams, and the difficulty in 

obtaining a sample that represents only dental amalgam discharges. Moreover, amalgam 

separators are an easy-to-use, relatively low cost technology. Dental offices that elect not to use 

an amalgam separator must still meet the proposed numeric limit and would be subject to the 

oversight and compliance requirements for indirect discharges subject to national pretreatment 

requirements. 

In selecting an amalgam separator that meets the requirements of the proposed

pretreatment standards, dentists would verify that the amalgam separator is compliant with the 

2008 ISO 11143 standard and meets the design specifications of the proposed regulation for their 

configuration. Once selected and installed, EPA expects dentists will operate and maintain the 

separator following all manufacturer’s instructions and conduct inspections at least monthly to 

ensure all features are functional. 

The proposed rule would subject all dentists (except certain specialists as described in 

Section 4.2) to categorical pretreatment requirements. EPA recognizes that some dentists 

potentially subject to the proposal do not apply or remove dental amalgam except, possibly, in 

limited emergency circumstances. However, EPA, in consultation with pretreatment authorities, 

has been unable to determine a publicly available source of information that would enable 

identification of dental offices where dental amalgam may reasonably be expected not to be 

present. As such, the proposed rule would apply to such dischargers and require them to report 

baseline information, but it would also allow them to certify (at any time) that they do not and 

8-2 
Section 8 - Regulatory Options 

will not install or remove amalgam (not including infrequent emergency treatment). This would 

fulfill their obligations under the proposed rule. If they subsequently elect to install or remove 

amalgam, they would then need to comply with the proposed numeric standard (e.g., proper 

operation and maintenance of an amalgam separator) and with the BMPs in the proposed rule. 

EPA does not want to penalize existing dental offices or institutional dental facilities that 

have already installed amalgam separators voluntarily or to comply with state or local 

requirements. EPA recognizes that these offices may currently have amalgam separators in place 

that are certified to a removal rate slightly lower than the proposed standard. For example, some 

states require dental offices to employ amalgam separators that are certified to remove 95 percent 

total mercury. EPA’s proposed rule does not require existing separators with a remaining useful 

life to be retrofitted with new separators. EPA chose to avoid imposing additional costs on dental 

facilities that moved ahead of EPA’s proposed requirements to install a treatment technology, 

and also chose to avoid the additional solid waste that would be generated by disposal of 

existing separators. Therefore, EPA is proposing that, as long as they continue to properly 

operate and maintain existing separators, comply with BMPs, and comply with recordkeeping 

requirements, these facilities would be considered in compliance with the numeric standard until 

10 years from the effective date of the final rule. EPA selected 10 years because it appears to be 

a conservative estimate of the useful life of the existing equipment. However, if a currently 

installed separator needs to be replaced before 10 years have elapsed, these facilities would need 

to install and operate an amalgam separator that meets the proposed removal efficiency of at 

least 99.0 percent. 

8.2 PRETREATMENT STANDARDS FOR NEW SOURCES (PSNS)

Under Section 307(c) of the CWA, new sources of pollutants into publicly owned 

treatment works (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. EPA proposes PSNS that would control the same pollutants 

using the same technologies proposed for control by PSES. The technologies used to control 

pollutants at existing offices, amalgam separators and BMPs, are fully applicable to new offices. 

New dental offices can incorporate amalgam separators into the design and installation of their 

vacuum system. Furthermore, EPA has not identified any technologies that are demonstrated for 

new sources that are more effective than those identified for existing sources. Finally, EPA has 

determined that the proposed PSNS present no barrier to entry. EPA has found that overall 

impacts from the proposed standards on new sources would not be any more severe than those on 

existing sources, since the costs faced by new sources generally will be the same as or less than 

those faced by existing sources. Therefore, EPA proposes to establish PSNS that are the same as

those proposed for existing sources (PSES). 

EPA does not propose to establish more stringent requirements for new sources based on 

technologies that remove dissolved mercury (i.e., polishing) for the same reasons stated above 

for existing standards. New sources would need to comply with the requirements discussed in 

Section 8.1.1. 

8-3 
Section 8 - Regulatory Options 

8.3 REFERENCES

ERG (Eastern Research Group). 2011. Polishing System for Removing Dissolved Mercury 

Review. Memorandum. Chantilly, VA. May 23. Document Control Number (DCN) 

DA00122. 

Garcia, A. 2009. EPA Audit Follow-Up Report. U.S. EPA Region 8. September 15. DCN 

DA00164. 

U.S. EPA. 2011. Economic Analysis for the Dental Amalgam Rule. MS ExcelTM file. Office of 

Water. Washington, DC. DCN DA00145.

8-4 
Section 9 - Costs of Technologies

SECTION 9

COSTS OF TECHNOLOGIES 

This section provides information on EPA’s approach for estimating compliance costs for 

dental offices. EPA’s cost methodology assumes dental offices would use the required best 

management practices (BMPs) in combination with 2008 ISO 11143 amalgam separators on the 

market today to comply (see Section 7.1.2). EPA categorized all of the costs as either capital 

costs (one-time costs associated with planning or installation of technologies), as operations and 

maintenance (O&M) costs (costs that occur on a regular ongoing basis such as inspection or 

cleaning of the unit or annual purchases of amalgam cartridges), or as reporting costs. Cost 

estimates are expressed in terms of 2010 dollars.

9.1 METHODOLOGY FOR DEVELOPING MODEL DENTAL OFFICE COSTS 

EPA estimated compliance costs associated with the proposed rule using data collected 

through EPA’s Health Services Industry Detailed Study (August 2008) [EPA-821-R-08-014], a 

review of the literature, and information supplied by vendors. EPA’s cost estimates represent the 

incremental costs for a dental office to comply with the proposed rule. For costing purposes, 

EPA differentiated dental offices by those that already use amalgam separators and those that do 

not. 

In general, one approach that EPA sometimes takes to estimate compliance costs is to use 

facility-specific data to determine what requirements apply to a given facility and whether that 

facility would already meet the proposed requirements. This approach requires substantial 

facility-specific technical and financial data. In the case of the Dental Category, EPA would need 

such data for approximately 110,000 dental offices estimated to be subject to this proposed 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, thereby modeling the full universe of affected facilities.

EPA used the model approach to estimate the costs to affected dental offices of 

complying with the proposed Dental Amalgam Rule. The model approach includes calculating 

compliance costs for dental offices based on the number of chairs at the practice (i.e., by size 

classes of dental offices). EPA developed compliance costs for six models based on the numbers 

of chairs in an office. The ranges for each model are: 1 to 2 chairs, 3 chairs, 4 chairs, 5 chairs, 6 

chairs, and 7+ chairs (average of 10 chairs). In addition to each of the size class models, EPA 

developed a model facility to represent very large offices such as clinics and universities. The 

costs for large facilities is discussed separately in Section 10. 

EPA developed two sets of costs for each model: one for dental offices that do not 

currently operate an amalgam separator and one for dental offices with that treatment technology 

in place. 

9-1 
Section 9 - Costs of Technologies

9.1.1 Model Compliance Costs for Dental Offices Without Amalgam Separators 

For offices that do not currently operate an amalgam separator, EPA estimated capital 

costs and O&M costs. Capital costs include the purchase of the amalgam separator and 

installation. Recurring costs include replacement of the cartridge and other O&M costs such as 

maintenance supply costs; inspection costs; maintenance costs; recycling preparation; and 

recycling costs. 

The costs of amalgam separators varies, but is relative to the size (number of chairs) of 

the dental practice. The number of amalgam separators required depends on the number of chairs 

in an office and the amalgam separator model. Wastewater flow rate determines how often filters 

and traps need to be cleaned/replaced (Walsh, 2007). Manufacturer suggested retail prices 

(MSRP) for an amalgam separator range from $210 to $3,984 (depending on the size of the 

dental office). Table 9-1 provides a summary of costs of commercially available amalgam 

separator systems (non-inclusive), including specific O & M costs for each model (in 2010 

dollars). 

Installation costs will also vary depending on the existing configuration of the dental 

office. Based on conversations with amalgam separator vendors, EPA estimated plumbing 

modifications for initial installation would cost $250, regardless of the size of the office (ERG, 

2010. 

9-2 
9-3 

Section 9 - Regulatory Options 

Table 9-1. Cost of Purchasing, Operating, and Maintaining Amalgam Separators ($2010)

Model Manufacturer MSRP Maintenance

Replacement 

Parts Recycling Reference

A1250 Air Techniques $1,000 Replace filter every 6–12 months. Filter: $250 Not included in 

MSRP

7 

AD-1000 American Dental 

Accessories

$809 Replace filter every 18 months. Filter: $504 Not included in 

MSRP

2 

Amalgam Boss M.A.R.S. Bio-Med 

Processes

$1,015 Unit switch out after 2 years for 1 

chair, 1.5 years for 2–3 chairs and 

1 year for 4–10 chairs. 

Separator unit: 

$1,015

Included in MSRP 1, 3

Amalgam Collector 

— CE18

R & D Services $839–$1,220 Recycle every 3 years; adjust 

liquid level tube every 6 months. 

Not available Recycling service: 

$254

1 

Amalgam Collector 

— CE24

R & D Services $1,265–$1,647 Recycle every 3 years; adjust 

liquid level tube every 6 months. 

Not available Recycling service: 

$305

1

Amalgam Collector 

— CH12

R & D Services $605–$986 Recycle every 4 years; adjust 

liquid level tube every 6 months. 

Not available Recycling service: 

$305

1

Amalgam Collector 

— CH9

R & D Services $626–$1,020 Recycle every 3 years; adjust 

liquid level tube every 6 months. 

Not available Recycling service: 

$316

2, 4

ARU-10 Hygenitek $770–$803 Replace ion cartridge every 6 

months, replace settlement tank 

every 2 years.

Cartridge, settling 

tanks: $179

Included in MSRP 5, 6

Asdex AS-10 Capsule Technologies $233 Replace filter every 6–8 months. Filter: $99 Not included in 

MSRP

1

Asdex AS-20 Capsule Technologies $332 Replace cartridge every 6–8 

months.

Cartridge: $198 Not included in 

MSRP

1

Asdex AS-20 American Dental 

Accessories

$300 Replace filter every 6–12 months. Filter: $177 Not included in 

MSRP

1, 8

Asdex AS-9 American Dental 

Accessories

$210 Replace filter every 6 months. Filter: $80 Not included in 

MSRP

8

BU10 Dental Recycling 

North America

$762 Replace canister every 12 

months.

Canister: $508 Included in MSRP 1, 9
9-4 

Section 9 - Regulatory Options 

Table 9-1. Cost of Purchasing, Operating, and Maintaining Amalgam Separators ($2010)

Model Manufacturer MSRP Maintenance

Replacement 

Parts Recycling Reference

BU30 Dental Recycling 

North America

$1,418 Replace canister every 12 

months.

Canister: $762 Included in MSRP 1, 9

Catch 1000 Plus Rebec Solutions $2,042 Replace canister every 12 

months.

Canister: $656 

(price is for 2 

canisters)

Included in MSRP 1, 10

Catch 400 Plus Rebec Solutions $1,204 Replace canister every 12 

months.

Canister: $656 

(price is for 2 

canisters)

Included in MSRP 1, 10

Catch 9000 Plus Rebec Solutions $3,984 Replace canister every 12 

months.

Canister: $910 

(price is for 3 

canisters)

Included in MSRP 1, 10

ECO II Pure Water 

Development

$570 Replace canister every 12 

months. 

Canister: $209 Not included in 

MSRP

1

Hg5 SolmteX $762 Replace cartridge every 6–12 

months. 

Cartridge: $304 Included in MSRP 1, 11

Hg5 High Volume SolmeteX $2,500 Replace cartridge every 12 

months.

Cartridge: $170–

$285

Not included in 

MSRP

1, 11

Hg5 Mini SolmeteX $762 Replace cartridge every 6–12 

months.

Cartridge: $304 Included in MSRP 1, 11

Liberty Boss M.A.R.S. Bio-Med 

Processes

$1,574 Unit switch out after 3 years for 

1–3 chairs, 2 years for 4–10 

chairs, 1 year for 11–17 chairs. 

Separator unit: 

$1,574

Included in MSRP 1

Merc II Bio-Sym Medical $1,300 Replace cartridge every 12 

months.

Cartridge: $495 Included in MSRP 5

MRU10 Dental Recycling 

North America

$1,250 Replace canister every 12 

months. 

Canister: $1,195 Included in MSRP 2, 9

MRU30 Dental Recycling 

North America

$1,795 Replace canister every 12 

months. 

Canister: $1,395 Included in MSRP 9

MSS 1000 Maximum Separation 

Systems

$1,288 Replace settling tank every 12 

months. 

Settling tank: 

$178

Not included in 

MSRP

2, 3
9-5 

Section 9 - Regulatory Options 

Table 9-1. Cost of Purchasing, Operating, and Maintaining Amalgam Separators ($2010)

Model Manufacturer MSRP Maintenance

Replacement 

Parts Recycling Reference

MSS 2000 Maximum Separation 

Systems

$1,418 Replace settling tank every 12–18 

months.

Settling tank: 

$168

Not included in 

MSRP

2

MSS 601 Maximum Separation 

Systems

$1,167 Replace settling tank every 12 

months.

Settling tank: 

$178

Not included in 

MSRP

3

Rasch 890-1000 AB Dental Trends $1,251 Replace canister every 12–18 

months

Canister: $627 Included in MSRP 2, 4

Rasch 890-1500 AB Dental Trends $731 Replace canister every 12–18 

months

Canister: $627 Included in MSRP 1, 4

Rasch 890-4000 AB Dental Trends $1,352–$1,931 Replace canister every 18 months Canister: $660–

$1,319

Included in MSRP 2

Rasch 890-6000 AB Dental Trends $700 Replace canister every 12–18 

months

Canister: $628 Included in MSRP 1, 4

Rasch 890-7000 AB Dental Trends $1,132 Replace canister every 12–18 

months.

Canister: $627 Included in MSRP 1, 4

Rasch AD-1500 American Dental 

Accessories

$675 Replace filter every 18 months. Filter: $470 Included in MSRP 1, 8

REM2000 

Series/Catch 1000

Rebec Solutions $2,028 Replace cartridge every 12 

months. 

Cartridge: $452 Included in MSRP 1, 10

REM2000 

Series/Catch 400

Rebec Solutions $1,204 Replace cartridge every 12 

months.

Cartridge: $452 Included in MSRP 1, 10

REM2000 

Series/Catch 9000

Rebec Solutions $3,984 Replace cartridge every 12 

months.

Cartridge: $808 Included in MSRP 2, 10

Average Cost for 1 to 2 Chairs $408–$596 $195

Average Cost for 3 to 5 Chairs $552–$645 $231

Average Cost for 6 Chairs $1,055-$1,060 $430

Average Cost for 7+ Chairs $1,509-$1,552 $629-$664

Sources: (1) – U.S. Air Force, 2011; (2) – MCES, 2009; (3) – MMSD and University of Wisconsin--Extension, 2006; (4) – ADA, 2007; (5) – McManus and 

Fan, 2003; (6) – SF Environment, 2005; (7) – ERG and Air Techniques, 2011; (8) – ERG and American Dental Accessories, 2011; (9) – ERG and DRNA, 

2011; (10) – ERG and Rebec Solutions, 2011; (11) – ERG and SolmeteX, 2011b.
Section 9- Costs of Technologies

Table 9-2 provides a summary of the one-time model facility costs for dental offices that 

do not currently use amalgam separators. The separator purchase cost for the various chair sizes 

in the average of the range provided in Table 9-1. 

Table 9-2. Summary of One Time Costs ($2010) to 

Model Dental Offices Without Amalgam Separators

Cost Element

Number of chairs in the model dental office

1 or 2 3, 4, or 5a 6 7+

Separator Purchase $502 $599 $1,058 $1,531

Installation $250 $250 $250 $250

Sources: See Table 9-1; ERG, 2010

a – EPA assumed the separator can be sized for 3, 4, or 5 chairs, but has kept these three model office sizes distinct 

because the economic analysis evaluates different revenues for each of these sized offices.

EPA also estimated annual costs which include O&M costs and separator replacement 

costs. Operation and maintenance costs include the following: 

• Inspection and maintenance: The proposal would require that the separator be 

inspected at least monthly. EPA included costs for a dental assistant ($17/hr18) to 

perform a five minute visual inspection monthly for all dental office sizes. The 

proposed rule would also require the separator to be maintained regularly. For all 

dental office sizes, EPA assumed maintenance would be performed by a dental 

assistant every two weeks and that each maintenance session would take 15 minutes. 

• Recycling preparation: Most separators require that their solids collectors and/or 

filters be replaced at least every 12 months. EPA assumed that a dental assistant 

($17/hr) would spend 15 minutes two times per year preparing materials for shipping 

and recycling for all dental office sizes.

• Recycling service costs: The range of recycling service costs provided by vendors is 

$0 (some include recycling costs as part of the original purchase cost) to $316 per 

recycling event (see Table 9-1). Assuming a conservative estimate of recycling every 

two years, the maximum annual cost for recycling service is $158 per year. EPA 

estimated recycling costs as the average of the range ($0 to $158), or $79 per year, for 

all dental office sizes (ERG, 2014). 

For separator replacement costs, EPA estimated that amalgam separators would have a 

service life of ten years, after which time the amalgam separator would need to be replaced. See 

Section 10.2.1. 

Table 9-3 provides a summary of annual model facility costs for dental offices that do not 

currently use amalgam separators.

18 Bureau of Labor Statistics reported a wage of $16.41 per hour for this job category in May 2011 (Bureau of Labor 

Statistics, 2011). EPA rounded up to $17 per hour.

9-6 

 
Section 9- Costs of Technologies

Table 9-3. Summary of Annual Costs ($2010) to Model Dental Offices 

Without an Amalgam Separator

Cost Element

Number of chairs in the model dental office

1 or 2 3, 4, or 5a 6 7+

Replacement Parts $195 $219 $430 $647

O & M including recycling $216 $216 $216 $216

Sources: See Table 9-1; U.S. EPA, 2011b. a EPA assumed the separator can be sized for 3, 4, or 5 chairs, but has kept these three model office sizes distinct 

because the economic analysis evaluates different revenues for each of these office sizes. 

9.1.2 Model Compliance Costs for Dental Offices Currently Using Amalgam Separators 

EPA also differentiated costs at the office level based on whether offices already have 

amalgam separators in place. EPA assumed that offices with treatment in place will incur no cost 

for purchasing and installing compliance technology at the time of initial regulatory compliance. 

However, EPA estimated additional permit-related costs (see Section 10.2) and some recurring 

incremental costs for such offices. Specifically, EPA assumed that dental offices with 

technology-in-place would incur recurring costs in relation to the costs otherwise incurred by 

offices without technology-in-place, as shown in Table 9-4 and Table 9-5. 

Table 9-4. Percentage of Recurring Costs Incurred by Dental Offices Currently Using

Amalgam Separators

Cost Category Percentage of Costs Incurreda

Replacement parts 50 percent

Amalgam separator maintenance 50 percent

Amalgam separator operation 100 percent

Recycling preparation and recycling service cost 50 percent a The percentage of costs estimated to be incurred by offices with technology-in-place relative to costs estimated to

be incurred by office without technology-in-place.

Source: U.S. EPA, 2011b.

Table 9-5. Summary of Annual Model Facility Costs ($2010) to Dental Offices Currently 

Using Amalgam Separators

Cost Element

Number of chairs in the model dental office

1 or 2 3, 4, or 5a 6 7+

Replacement Parts $98 $110 $215 $324

O & M including recycling $116 $116 $116 $116

a EPA assumed the separator can be sized for 3, 4, or 5 chairs, but has kept these three model office sizes distinct 

because the economic analysis evaluates different revenues for each of these office sizes. 

9.2 REPORTING REQUIREMENTS AND BMP COSTS

All dental offices subject to the proposed Dental Amalgam Rule will have reporting 

requirements and BMP requirements. EPA included reporting costs for one-time preparation of a 

9-7 
Section 9- Costs of Technologies

baseline report and initial compliance report19 and recurring costs associated with preparation of 

an annual certification statement. EPA estimates that an office or dental assistant would require 

the following times to complete each report:

• 76 minutes to complete the baseline monitoring report; 

• 51 minutes to complete the initial compliance report; and

• 49 minutes to complete the annual certification statement.

As has been mentioned, EPA recognizes that some dental offices subject to the proposed 

rule do not place or remove amalgam and has proposed a provision that allows non-users of 

amalgam to submit a one-time baseline monitoring report to certify that they do not use amalgam 

except in unusual emergency circumstances. Should the status of a non-using dental office 

change, the certification would no longer be valid. For example, if a dental office so certifies and 

is sold, the new owner must similarly so certify or would need to comply with the rule. See CFR 

441.10. 

Assuming a labor rate of $17 per hour for a dental assistant (based on Bureau of Labor 

Statistics for May 2011), EPA estimates that the cost to complete the baseline monitoring report 

is $22, the cost to complete the initial compliance report is $15, and the cost to complete the 

annual certification is $14 (U.S. EPA, 2011a).

EPA did not include incremental costs for BMPs because (1) costs for non-oxidizing, pH 

neutral line cleaners are roughly equivalent to other line cleaners; and (2) dentists will not incur 

additional costs by changing the location for flushing scrap amalgam. 

9.3 METHODOLOGY FOR DEVELOPING COSTS FOR INSTITUTIONAL FACILITIES

Institutional dental service facilities (e.g., clinics or dental schools), have a larger number 

of chairs than the typical dental office. For these institutional dental facilities, EPA developed a 

costing methodology based on the methodology for offices described above. For purposes of 

costs, EPA assumed the average institutional facility has 15 chairs. In the methodology described 

previously, the model practice with the largest number of chairs for which EPA developed cost 

information is the 7+ chair model with an average of 10 chairs. EPA estimated that these 

facilities would incur compliance technology costs in the same categories as other facilities, with 

compliance equipment costs being 50 percent greater than those incurred by facilities in the 7+ 

chairs category. All other costs are the same as those incurred by facilities in the 7+ chairs 

category (U.S. EPA, 2011b). These costs are likely overstated as they do not reflect opportunities 

the largest offices may have to share costs,20 and they do not assume any economies of scale. 

Section 10 provides further details on costs developed for larger dental facilities. 

9.4 REFERENCES

ADA (American Dental Association). 2007. ADA Professional Product Review. Document 

Control Number (DCN) DA00043. 

19 These are required under 40 CFR 403.

20 For example, multiple dental offices located in the same building or complex may be able to share plumbing, 

vacuum systems, and may be able to install a larger separator, rather than each office having its own system.

9-8 

 
Section 9- Costs of Technologies

Bureau of Labor Statistics. 2011. May 2011 National Occupational Employment and Wage 

Estimates. May. DCN DA00250. 

ERG (Eastern Research Group). 2010. SolmeteX meeting minutes for 15 December 2010. 

Chantilly, VA. DCN DA00081. 

ERG. 2014. Pollution Prevention Program Costs for Controlling Dental Amalgam Discharges. 

Memorandum. September 22. Chantilly, VA. DCN DA00249. 

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. 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. 

ERG and SolmeteX. 2011b. Notes from telephone conversation between Kimberly Landick, 

ERG and SolmeteX, March 2, 2011: Subject Amalgam Separator Questions. DCN 

DA00064. 

MCES (Metropolitan Council Environmental Services). 2009. Revised – Features of Approved 

Amalgam Separators. March. 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.

SF Environment. 2005. San Francisco Department of the Environment. San Francisco City and 

County List of Approved Amalgam Separators. March. DCN DA00077. 

U.S. Air Force. 2011. Synopsis of Dental Amalgam Separators. January 24. Dental Evaluation 

and Consultation Service. DCN DA00079. 

U.S. EPA. 2011a. EPA Analysis: Part 441 Option Cost Calculations. MS ExcelTM file. Office of 

Water. Washington, DC. DCN DA00146. 

U.S. EPA. 2011b. Economic Analysis for the Dental Amalgam Rule. MS ExcelTM file. Office of 

Water. Washington, DC. DCN DA00145. 

9-9 
Section 9- Costs of Technologies

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. 

9-10 
Section 10 - Economic Impacts for the Dental Industry

SECTION 10

ECONOMIC IMPACTS FOR THE DENTAL INDUSTRY

This section describes EPA’s economic impact assessment of the proposed Dental 

Amalgam Rule, and is organized as follows: 

• Section 10.1 reviews the structure of the regulated sector in terms of number of dental 

offices potentially subject to the proposed Dental Amalgam Rule and the distribution 

of these offices by revenue. 

• Section 10.2 presents the compliance costs that EPA expects would be incurred by 

dental offices under the proposed rule. 

• Section 10.3 combines the estimates of numbers of in-scope offices by relevant 

operating characteristics to estimate total nationwide compliance costs for the 

proposed rule. 

• Section 10.4 assesses the social cost of the proposed Dental Amalgam Rule, including 

costs to dental offices (and facilities)21 and the costs to permitting authorities for 

administering rule requirements.

• Section 10.5 determines the potential for significant economic impact on small dental 

office entities as a result of the proposed rule. 

10.1 OVERVIEW OF DENTAL OFFICES POTENTIALLY SUBJECT TO PROPOSED REGULATION

In this section, EPA reviews its estimate of the number of dental offices that might be 

within the scope of the proposed 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 facilities 

using mercury-containing materials (dental amalgam); (2) the number of dental 

facilities that currently use treatment technology; and (3) as a result, the costs likely 

to be incurred by dental offices in complying with the proposed rule. 

10.1.1 Number of Dental Offices Potentially Subject to the Proposed Regulation

To support the assessment of total costs and economic impact of the proposed Dental 

Amalgam Rule, EPA relied on data from the 2007 Economic Census describing the number of 

firms and establishments in the dental office sector (NAICS 621210), and their annual receipts 

(revenue). EPA used the 2007 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 

21 As explained in Section 2, dental offices include but are not limited to institutions, permanent or temporary 

offices, clinics, mobile units, home offices, and facilities, including dental facilities owned and operated by Federal, 

state or local governments.

10-1 

 
Section 10 - Economic Impacts for the Dental Industry

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 proposed Dental Amalgam Rule. Therefore, EPA estimated compliance costs 

for each dental office size. In addition, in reviewing the 2007 Economic Census data for the 

dental office sector, EPA observed that almost all firms are single-establishment/single-office 

firms. The total of 127,057 establishments/offices is owned by 121,048 firms — thus no more 

than 6,009 firms, or fewer than 5 percent of firms, can be 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 2007 Economic Census counts of dental offices, EPA applied a number 

of adjustments to estimate the number of dental offices, in aggregate and by revenue range, that 

could be within the scope of the proposed Dental Amalgam Rule: 

• As shown in Table 10-1, the Economic Census listed 127,057 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 2007 dollars. 

EPA performed its cost and economic impact analysis based on 2010 dollar values. 

Because the Economic Census revenue ranges are defined in 2007 dollars, EPA 

adjusted these dollar values defining the revenue ranges to 2010 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 2007 and 

2010 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 2007–2010 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 127,057 total offices, the Economic Census reported 116,792 offices as being 

in business for the full 2007 year and 10,265 offices as being in business for only part 

of the year. The numbers of dental offices listed in the 11 revenue ranges represent 

the 116,792 offices that were in business for the full 2007 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 10,265 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 proposed Dental 

10-2 
Section 10 - Economic Impacts for the Dental Industry

Amalgam Rule. The tenth revenue range includes the Small Business Administration 

revenue cutoff ($7.0 million), and EPA assigned none of the partial-year offices to 

this range.22 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 ($2007) Revenue Ranges ($2010) Number 

Establishments

Adjusted Number 

Establishmentsa Low High Low High

0 $10,000 0 $10,448 160 174

$10,000 $24,999 $10,449 $26,120 471 513

$25,000 $49,999 $26,121 $52,242 940 1,023

$50,000 $99,999 $52,243 $104,485 2,401 2,613

$100,000 $249,999 $104,486 $261,213 13,034 14,183

$250,000 $499,999 $261,214 $522,427 28,766 31,303

$500,000 $999,999 $522,428 $1,044,856 42,803 46,578

$1,000,000 $2,499,999 $1,044,857 $2,612,141 25,046 27,255

$2,500,000 $4,999,999 $2,612,142 $5,224,283 2,783 3,028

$5,000,000b $9,999,999 $5,224,284 $10,448,567 330 330

$10,000,000 Or more $10,448,568 Or more 58 58

Establishments operated for the entire year 116,792 127,057

Establishments not operated for the entire year 10,265 -

Total Establishments 127,057 127,057

Sources: Census, 2007; U.S. EPA, 2011c.

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 SBA 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 

130 large institutional dental facilities (e.g., clinics or dental schools, see Section 4.1). Adding 

these 130 facilities to the 127,057 dental offices from the Economic Census brings the total of 

dental offices and facilities that are potentially within the rule’s scope to 127,187. 

10.1.2 Adjustments to Account for Baseline Status

EPA also accounted for additional factors that will influence the extent to which dental 

office sector would incur costs under the proposed Dental Amalgam Rule: 

• First, EPA recognized that certain specialty dental practices do not place or remove 

dental amalgam (see Section 4.2) and thus did not include them in the scope of the 

proposed 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. 

Within this group of specialty practices, approximately 65 percent do not place or 

remove dental amalgam (ADA, 2010a; Vandeven and McGinnis, 2005). As a result, 

of the total of dental offices, EPA estimated that approximately 14 percent are 

22 See discussion in Section 10.5 for information on the assessment of small entity impacts.

10-3 

 
Section 10 - Economic Impacts for the Dental Industry

specialists that would not be subject to the proposed rule.23 Because the proposed rule 

would not apply to them, EPA assigned no compliance-related costs to these 17,215 

offices, and these offices are not included in the impacts analysis (U.S. EPA, 2011c). 

• Second, EPA divided the in-scope offices 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. From a review of state requirements, 

EPA estimates that 40 percent of offices have amalgam separators in place already, 

and used this percentage to categorize offices as technology-in-place offices and notechnology-in-place offices (U.S. EPA, 2011a). 

• Third, among the remaining 60 percent of offices that have not already installed 

amalgam separators, EPA estimated that approximately 20 percent of these dental 

offices do not place or remove dental amalgam (Pimpare, 2012) and thus would incur 

no treatment technology-related costs due to the proposed Dental Amalgam Rule. 

These 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 facilities, with these further breakouts. EPA carried these estimated numbers of 

dental offices and large facilities by baseline amalgam use and compliance status forward to the 

cost and economic impact analysis. 

23 0.21 × 0.65 ≈ 0.135. See U.S. EPA, 2011a, for further information on this estimate.

10-4 

 
Section 10 - Economic Impacts for the Dental Industry

10-5 

Table 10-2. Adjusting Office Counts to Account for Baseline Amalgam Use and Technology in Place

Revenue Ranges ($2010) 

(see Table 10-1)

Number of Offices

Total 

(see Table 10-1)

Not Using 

Amalgam

Using 

Amalgam

Technology-InPlace

No-Technology-In-Place

Low High Total

With Technology 

Costs

No Technology 

Costs

0 $10,448 174 24 151 61 90 72 18

$10,449 $26,120 513 69 443 179 264 211 53

$26,121 $52,242 1,023 138 884 358 527 421 105

$52,243 $104,485 2,613 354 2,259 913 1,346 1,077 269

$104,486 $261,213 14,183 1,920 12,264 4,958 7,305 5,844 1,461

$261,214 $522,427 31,303 4,237 27,066 10,943 16,123 12,898 3,225

$522,428 $1,044,856 46,578 6,304 40,273 16,282 23,991 19,193 4,798

$1,044,857 $2,612,141 27,255 3,689 23,566 9,528 14,038 11,230 2,808

$2,612,142 $5,224,283 3,028 410 2,619 1,059 1,560 1,248 312

$5,224,284 $10,448,567 330 45 285 115 170 136 34

$10,448,568 Or more 58 8 50 20 30 24 6

Total Economic Census 127,057 17,198 109,859 44,416 65,443 52,355 13,089

Institutional Facilities 130 18 112 45 67 54 13

Total 127,187 17,215 109,972 44,462 65,510 52,408 13,102

Percentage adjustment factors 13.5% 86.5% 40.4% 59.6% 80.0% 20.0%

Sources: Census, 2007 and U.S. EPA, 2011c.
Section 10 - Economic Impacts for the Dental Industry

10.2 SUMMARY OF THE PROPOSED 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 proposed rule. 

10.2.1 Summary of Compliance Costs

Using the methodology described in Section 9, EPA developed compliance costs for 

model facilities with and without amalgam separators. As described in Section 9, EPA assumed 

that offices with treatment-in-place would incur no cost for purchasing and installing compliance 

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 Section 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 six number-of-chair ranges, as follows:

• 1 to 2 chairs; 

• 3 chairs; 

• 4 chairs; 

• 5 chairs; 

• 6 chairs; and 

• 7+ chairs. 

EPA also estimated costs for the large institutional facilities (such as clinics or 

universities). For purposes of costs, EPA assumed the average institutional facility has 15 chairs. 

See Section 9.3 for more details. 

Table 10-3 lists estimated compliance costs for offices that have and have not already 

installed amalgam separators, in 2010 dollars, by cost category and by size (i.e., number of 

chairs). A size category for large facilities (which average 15 chairs) is also included.

10-6 
10-7 

Section 10 - Economic Impacts for the Dental Industry

Table 10-3. Dental Office Compliance Costs by Cost Category and Number of Chairs (2010 dollars)

Cost Element

No-Technology-In-Place Technology-In-Place

Operating Size: Number of Chairs and Large Facilities Operating Size: Number of Chairs and Large Facilities

1–2 3 4 5 6 7+

Large 

Fac. 1–2 3 4 5 6 7+

Large 

Fac.

Technology Installation and Other Startup Costs

Equipment 

purchase 

$502 $599 $599 $599 $1,058 $1,531 $2,297 $0 $0 $0 $0 $0 $0 $0

Installation $250 $250 $250 $250 $250 $250 $250 $0 $0 $0 $0 $0 $0 $0

One-time baseline 

monitoring report 

(BMR)

$22 $22 $22 $22 $22 $22 $22 $22 $22 $22 $22 $22 $22 $22

One-time 

compliance report

$15 $15 $15 $15 $15 $15 $15 $15 $15 $15 $15 $15 $15 $15

Annual Costs

Replacement parts $195 $219 $219 $219 $430 $647 $647 $98 $110 $110 $110 $215 $324 $324

Separator 

maintenance

$111 $111 $111 $111 $111 $111 $111 $55 $55 $55 $55 $55 $55 $55

Recycling 

preparation

$9 $9 $9 $9 $9 $9 $9 $4 $4 $4 $4 $4 $4 $4

Recycling service $79 $79 $79 $79 $79 $79 $79 $40 $40 $40 $40 $40 $40 $40

Visual Inspection $17 $17 $17 $17 $17 $17 $17 $17 $17 $17 $17 $17 $17 $17

Annual 

certification

$14 $14 $14 $14 $14 $14 $14 $14 $14 $14 $14 $14 $14 $14

Source: U.S. EPA, 2011c.
Section 10 - Economic Impacts for the Dental Industry

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 

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 dental offices would incur 

ongoing expenses in the same way as described in the preceding paragraphs and Table 10-3. 

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 1–10.24 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 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 seven percent, which is intended to represent 

the opportunity cost of capital to society, on a pre-tax, constant dollar basis.25 The resulting 

present value is then annualized over the full 20-year analysis period at the seven percent interest 

rate. EPA used the resulting total annualized compliance costs in assessing the total estimated 

cost and impact of the proposed rule to dental offices, as described in subsequent sections. Table 

10-3 and Table 10-4 report specific elements of compliance costs and summarize the tabulation 

of costs to develop estimates of the total annualized compliance cost to dental offices. 

Table 10-4, below, summarizes the tallying of these costs according to the initial 

installation and reinstallation specifications, and present value and annualized cost calculations, 

as described above. 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 seven percent discount 

rate. The resulting annualized costs include all of the cost elements except for operational and 

annual certification costs, which are tallied in the final part of the table. Because these costs are 

incurred annually and do not vary by technology-in-place status, they are simply added to the 

annualized cost values in Table 10-4 to calculate the total annualized costs to dental offices and 

large facilities for the proposed rule. 

24 Where year 1 would be the first year in which a facility complies with the rule. 25 For the assessment of the rule’s social costs, EPA used an additional discount rate of 3 percent and also applied a 

different discounting treatment (see Section 10.4).

10-8 

 
Section 10 - Economic Impacts for the Dental Industry

10-9 

Table 10-4. Summary of Annualized Compliance Costs for a Dental Office or Large Facility, Accounting 

for Initial Installation and Reinstallation of Amalgam Separators, and Operational and Certification Costs

Cost Element

No-Technology-In-Place Technology-In-Place

Operating Size: Number of Chairs and Large Facilities Operating Size: Number of Chairs and Large Facilities

1–2 3 4 5 6 7+

Large 

Fac. 1–2 3 4 5 6 7+

Large 

Fac.

Initial Installation Analysis

Total initial outlay $789 $886 $886 $886 $1,345 $1,818 $2,584 $37 $37 $37 $37 $37 $37 $37

Total annual (recurring) costs $393 $417 $417 $417 $628 $845 $845 $197 $209 $209 $209 $314 $423 $423

Present value total annual 

(recurring) $2,760 $2,929 $2,929 $2,929 $4,411 $5,935 $5,935 $1,380 $1,464 $1,464 $1,464 $2,205 $2,967 $2,967

Total present value, at year 1 $3,549 $3,815 $3,815 $3,815 $5,756 $7,753 $8,519 $1,417 $1,502 $1,502 $1,502 $2,243 $3,005 $3,005

Reinstallation Analysis — Equipment Reinstalled at Beginning of Year 11

Total initial outlay (0.5 

installation charge)

$664 $761 $761 $761 $1,220 $1,693 $2,459 $664 $761 $761 $761 $1,220 $1,693 $2,459

Total annual (recurring) costs $393 $417 $417 $417 $628 $845 $845 $197 $209 $209 $209 $314 $423 $423

Present value total annual 

(recurring) $2,760 $2,929 $2,929 $2,929 $4,411 $5,935 $5,935 $1,380 $1,464 $1,464 $1,464 $2,205 $2,967

$2,967

Total present value, at year 11 $3,424 $3,690 $3,690 $3,690 $5,631 $7,628 $8,394 $2,044 $2,226 $2,226 $2,226 $3,426 $4,661 $5,426

Total present value, at year 1 $1,741 $1,876 $1,876 $1,876 $2,862 $3,878 $4,267 $1,039 $1,131 $1,131 $1,131 $1,741 $2,369 $2,758

Combining Initial Installation and Re-Installation

Sum, present values at year 1 $5,290 $5,691 $5,691 $5,691 $8,618 $11,631 $12,785 $2,456 $2,633 $2,633 $2,633 $3,984 $5,374 $5,763

Annualized cost over 20 years $499 $537 $537 $537 $814 $1,098 $1,207 $232 $249 $249 $249 $376 $507 $544

Including Operational and Certification

Visual Inspection $17 $17 $17 $17 $17 $17 $17 $17 $17 $17 $17 $17 $17 $17

Annual certification $14 $14 $14 $14 $14 $14 $14 $14 $14 $14 $14 $14 $14 $14

Total Annualized Cost $531 $569 $569 $569 $845 $1,129 $1,238 $263 $280 $280 $280 $408 $539 $575 

Present values and annualized costs are calculated using a 7 percent discount rate. All costs are on a pre-tax basis, in 2010 dollars, and as of the time of compliance by 

complying entities. The social cost analysis uses an additional 3 percent discount rate and applies a different discounting treatment. 

Source: U.S. EPA, 2011c.
Section 10 - Economic Impacts for the Dental Industry

As discussed in Section 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 proposed Dental Amalgam Rule. Although 

these offices will not incur treatment technology-related compliance costs, they will incur the 

cost of the one-time baseline monitoring report to document that they do not use amalgam in 

their operations. EPA estimates this cost to be $22 for each of these offices/facilities. In 

calculating the total compliance cost for the proposed rule, this value is annualized using the 

discount rate and number of periods for non-recurring outlays, and added to the total rule costs 

for offices and facilities 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 Section 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, 2010b). This study, called the “ADA National Study” below, indirectly 

reports a distribution of number of chairs by office. 

Table 10-5 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.

Table 10-5. 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%

10-10 
Section 10 - Economic Impacts for the Dental Industry

Table 10-5. Distribution of the Number of Chairs in Dental Offices

Number of Chairs in Office Frequency Relative Frequency Running Total, Frequency

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%

Sources: ADA, 2009, 2010b.

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.26 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 10-6 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 large institutional facilities. Large institutional facilities are not included in this tally 

because EPA possesses no information on their revenue.

26 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.

10-11 

 
Section 10 - Economic Impacts for the Dental Industry

10-12 

Table 10-6. Number of Chairs in Dental Offices by Revenue Range

Revenue Range Values ($2010) 

(see Table 10-2)

Offices By Revenue Range

(see Table 10-2) With Allocation by Number of Chairs in Office

Low High

Number of 

Offices

Percent of

Total

Offices

Running 

Total 

Percent

Number 

of 

Chairs

Number 

of Offices

Running 

Total

Percent of

Total

Offices

Running 

Total 

Percent

Cumulative

Percent from ADA 

Distribution

Using ADA Colorado Study Distribution

0 $10,448 174 0.1% 0.1% 1–2 174 174 0.1% 0.1% 9.74%

$10,449 $26,120 513 0.4% 0.5% 1–2 513 687 0.4% 0.5%

$26,121 $52,242 1,023 0.8% 1.4% 1–2 1,023 1,710 0.8% 1.4%

$52,243 $104,485 2,613 2.1% 3.4% 1–2 2,613 4,322 2.1% 3.4%

$104,486 $193,476 14,183 11.2% 14.6% 1–2 8,053 12,376 6.3% 9.7%

$193,477 $261,213 3 6,130 18,506 4.8% 14.6% 35.06%

$261,214 $478,568 31,303 24.6% 39.2% 3 26,047 44,552 20.5% 35.1%

$478,569 $522,427 4 5,256 49,808 4.1% 39.2% 64.29%

$522,428 $879,904 46,578 36.7% 75.9% 4 31,871 81,680 25.1% 64.3%

$879,905 $1,044,856 5 14,706 96,386 11.6% 75.9% 78.57%

$1,044,857 $1,242,938 27,255 21.5% 97.3% 5 3,445 99,831 2.7% 78.6%

$1,242,939 $1,868,020 6 10,870 110,700 8.6% 87.1% 84.42%

$1,868,021 $2,612,141 7+ 12,940 123,641 10.2% 97.3% 100.00%

$2,612,142 $5,224,283 3,028 2.4% 99.7% 7+ 3,028 126,669 2.4% 99.7%

$5,224,284 $10,448,567 330 0.3% 99.9% 7+ 330 126,999 0.3% 99.9%

$10,448,568 Or more 58 0.1% 100.00% 7+ 58 127,057 0.1% 100.00%

Total27 127,057 100.00% — 127,057 100.00%

Using ADA National Study Distribution 

0 $10,448 174 0.1% 0.1% 1–2 174 174 0.1% 0.1% 12.46%

$10,449 $26,120 513 0.4% 0.5% 1–2 513 687 0.4% 0.5%

$26,121 $52,242 1,023 0.8% 1.4% 1–2 1,023 1,710 0.8% 1.4%

$52,243 $104,485 2,613 2.1% 3.4% 1–2 2,613 4,322 2.1% 3.4%

$104,486 $231,731 14,183 11.2% 14.6% 1–2 11,515 15,838 9.1% 12.5%

$231,732 $261,213 3–4 2,668 18,506 2.1% 14.6% 55.88%

$261,214 $522,427 31,303 24.6% 39.2% 3–4 31,303 49,808 24.6% 39.2%

$522,428 $760,147 46,578 36.7% 75.9% 3–4 21,194 71,002 16.7% 55.9%

$760,148 $1,044,856 5–6 25,383 96,386 19.9% 75.9% 82.63%

$1,044,857 $1,539,698 27,255 21.5% 97.3% 5–6 8,605 104,991 6.8% 82.6%

27 The total 127,057 offices include the entire dental industry, including those dental specialists discussed in Section 4.2 that are outside the scope of the proposed rule.

 
Section 10 - Economic Impacts for the Dental Industry

10-13 

Table 10-6. Number of Chairs in Dental Offices by Revenue Range

Revenue Range Values ($2010) 

(see Table 10-2)

Offices By Revenue Range

(see Table 10-2) With Allocation by Number of Chairs in Office

Low High

Number of 

Offices

Percent of

Total

Offices

Running 

Total 

Percent

Number 

of 

Chairs

Number 

of Offices

Running 

Total

Percent of

Total

Offices

Running 

Total 

Percent

Cumulative

Percent from ADA 

Distribution

$1,539,699 $2,612,141 7+ 18,650 123,641 14.7% 97.3% 100.00%

$2,612,142 $5,224,283 3,028 2.4% 99.7% 7+ 3,028 126,669 2.4% 99.7%

$5,224,284 $10,448,567 330 0.3% 99.9% 7+ 330 126,999 0.23% 99.9%

$10,448,568 Or more 58 0.1% 100.00% 7+ 58 127,057 0.1% 100.00%

Total 127,057 100.00% — 127,057 100.00%

Source: U.S. EPA, 2011c.
Section 10 - Economic Impacts for the Dental Industry

10.3 ESTIMATED COST OF COMPLIANCE TO DENTAL OFFICES 

To estimate the total nationwide cost of compliance to dental offices of the proposed rule, 

EPA multiplied the estimated total annualized cost of rule compliance by the number of chairs 

for dental offices (see Section 10.1.2). For large institutional facilities, compliance costs are 

multiplied by the estimated number of facilities in the resulting size ranges (see Table 10-6 and 

Table 10-8). 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 entities— dental offices and large institutional facilities— 

as of the year of compliance.

EPA completed these calculations separately for the two distributions of offices by 

number of chairs. Table 10-7 summarizes the results from these calculations. These total 

compliance cost estimates include the one-time compliance costs for dental offices that do not 

process dental amalgam, as described in Section 10.2.1. 

Table 10-7. Annualized Costs to Complying Dental Offices by Number of 

Chairs

Annualized Cost (Millions, $2010) for Alternative Number-of-Chairs Distributions

Number of Chairs Colorado Survey ADA Survey

1–2 chairs $3.8 $4.9

3 chairs $10.7 $18.3 4 chairs $12.3

5 chairs $6.0 $16.7 6 chairs $5.3

7+ chairs $10.7 $14.4

Large facilities $0.1 $0.1

Total Costs $49.0 $54.5

Present values and annualized costs are calculated using a 7 percent discount rate. All costs 

are on a pre-tax basis, in $2010, and as of the time of compliance by complying entities. 

Source: U.S. EPA, 2011c.

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 estimates 

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/facilities. 

10.3.1 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 

proposed rule to current (or pre-rule) dental office revenues (Section 10.3.1.1). In addition, EPA 

chose to examine the financial impacts of the proposed rule using two measures that utilize the 

data EPA has on dental office baseline assets and estimated replacement capital costs: (1) ratio of 

the proposed rule’s capital costs to total dental office capital assets (Section 10.3.1.2); and (2) 

10-14 
Section 10 - Economic Impacts for the Dental Industry

ratio of the proposed rule’s capital costs to annual dental office capital replacement costs 

(Section 10.3.1.3).

10.3.1.1 Cost-to-Revenue Analysis

The cost-to-revenue measure compares the annualized cost of regulatory compliance, at a 

seven 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-torevenue 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 Section 10.5 below.

EPA framed the cost-to-revenue analysis around the revenue range/number-of-chairs 

combinations, as developed in Table 10-6, and the total annualized compliance costs that would 

occur within each of these analysis combinations. Table 10-8 summarizes these analytic 

combinations. Note that EPA was not able to perform the cost-to-revenue impact analysis for 

large institutional facilities, 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 large institutional facilities.

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 proposed 

Dental Amalgam 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 10-8. Revenue Range/Number-of-Chairs 

Combinations for Cost Impact Analysis 

Revenue Range/Number of Chairs Combinations Number of 

Offices

Percent of Total 

Low High Number of Chairs Offices

Using ADA Colorado Study Distribution

0 $10,448 1–2 151 0.1%

$10,449 $26,120 1–2 443 0.4%

$26,121 $52,242 1–2 884 0.8%

$52,243 $104,485 1–2 2,259 2.1%

$104,486 $193,476 1–2 6,963 6.3%

$193,477 $261,213 3 5,300 4.8%

$261,214 $478,568 3 22,521 20.5%

$478,569 $522,427 4 4,545 4.1%

$522,428 $879,904 4 27,557 25.1%

$879,905 $1,044,856 5 12,716 11.6%

$1,044,857 $1,242,938 5 2,978 2.7%

$1,242,939 $1,868,020 6 9,399 8.6%

$1,868,021 $2,612,141 7+ 11,189 10.2%

$2,612,142 $5,224,283 7+ 2,619 2.4%

10-15 
Section 10 - Economic Impacts for the Dental Industry

Table 10-8. Revenue Range/Number-of-Chairs 

Combinations for Cost Impact Analysis 

Revenue Range/Number of Chairs Combinations Number of 

Offices

Percent of Total 

Low High Number of Chairs Offices

$5,224,284 $10,448,567 7+ 285 0.3%

$10,448,568 Or more 7+ 50 0.1%

Total 109,859 100.00%

Using ADA National Study Distribution

0 $10,448 1–2 151 0.1%

$10,449 $26,120 1–2 443 0.4%

$26,121 $52,242 1–2 884 0.8%

$52,243 $104,485 1–2 2,259 2.1%

$104,486 $231,731 1–2 9,957 9.1%

$231,732 $261,213 3–4 2,307 2.1%

$261,214 $522,427 3–4 27,066 24.6%

$522,428 $760,147 3–4 18,325 16.7%

$760,148 $1,044,856 5–6 21,948 20.0%

$1,044,857 $1,539,698 5–6 7,440 6.8%

$1,539,699 $2,612,141 7+ 16,125 14.7%

$2,612,142 $5,224,283 7+ 2,619 2.4%

$5,224,284 $10,448,567 7+ 285 0.3%

$10,448,568 Or more 7+ 50 0.1%

Total 109,85928 100.00%

Source: U.S. EPA, 2011c.

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 

28 The total 109,859 dental offices are all in-scope dental offices for the proposed Dental Amalgam Rule as 

described in Section 10.1.2. The total does not include large facilities as noted in this section.

10-16 

 
Section 10 - Economic Impacts for the Dental Industry

revenue threshold. To calculate the number of offices with costs exceeding the 

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 RVmin)-(RVbe = threshold ÷ (RVmax RVmin)-

Where:

RVbe = Break-even revenue 

RVmin = Minimum value in revenue range

RVmax = 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 proposed 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 

2007 Economic Census reports that approximately 700 offices of the approximately 110,000 

total offices had revenue of less than $25,000 (2007 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 proposed 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 inkind 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 

third part of the cost impact analysis (Section 10.3.1.3, below). Specifically, in this 

10-17 
Section 10 - Economic Impacts for the Dental Industry

analysis, EPA estimated that one- to two-chair offices would incur capital 

replacement costs of approximately $23,500 per year (the estimated annual cost of 

keeping equipment in good working order) (U.S. EPA, 2011c). This outlay would 

exceed or represent a very substantial fraction of 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 $23,500 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-torevenue exceeding the one and three percent of revenue thresholds for the proposed 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. Table 10-9 and Table 10-10 summarize the results from this analysis. Table 10-9

reports the results by technology-in-place status; Table 10-10 reports the results by number-ofchair 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 507 

dental offices would incur costs exceeding one percent of revenue, representing 0.5 percent of 

dental offices expected to incur costs under the proposed regulation. No offices incur costs 

exceeding three percent of revenue. With the baseline set-aside offices included in the analysis, 

EPA estimates that 965 dental offices would incur costs exceeding one percent of revenue, 

representing 0.9 percent of dental offices expected to incur costs under the proposed rule; 221 

offices are estimated to incur costs exceeding three percent of revenue, representing 0.2 percent 

of offices expected to incur costs under the proposed 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 $7.0 million. This finding is relevant for Section 10.5. 

Table 10-9. Cost-to-Revenue Impact Summary

Offices with Cost Exceeding 1 Percent of Revenue Offices with Cost Exceeding 3 Percent of Revenue

TechnologyIn-PlaceNo-Techin-PlaceTotal Percentage TechnologyIn-PlaceNo-Techin-PlaceTotal Percentage

Excluding Baseline Set-Aside Offices from Analysis 

33 474 507 0.5% 0 0 0 0.0%

10-18 
Section 10 - Economic Impacts for the Dental Industry

Table 10-9. Cost-to-Revenue Impact Summary

Offices with Cost Exceeding 1 Percent of Revenue Offices with Cost Exceeding 3 Percent of Revenue

TechnologyIn-PlaceNo-Techin-PlaceTotal Percentage TechnologyIn-PlaceNo-Techin-PlaceTotal Percentage

Including Baseline Set-Aside Offices in Analysis 

243 722 965 0.9% 51 169 221 0.2%

Calculations exclude the estimated 13,000 offices with no-technology-in-place that do not place or remove dental 

amalgam (and thus will incur only a minimal one-time reporting cost). 

Percentages of affected offices are calculated as a fraction of total offices estimated to incur costs under the 

proposed Dental Amalgam Rule.

Source: U.S. EPA, 2011c.

Table 10-10. Cost-to-Revenue Impact Summary by Number of Chairs

Number of 

Chairs

Excluding Baseline Set-Aside Offices from 

Analysis

Including Baseline Set-Aside Offices in 

Analysis

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

Number % Number % Number % Number %

1–2 chairs 507 4.2% — 0.0% 965 7.9% 221 1.8%

3 chairs — 0.0% — 0.0% — 0.0% — 0.0%

4 chairs — 0.0% — 0.0% — 0.0% — 0.0%

5 chairs — 0.0% — 0.0% — 0.0% — 0.0%

6 chairs — 0.0% — 0.0% — 0.0% — 0.0%

7+ chairs — 0.0% — 0.0% — 0.0% — 0.0%

Total 507 0.5% — 0.0% 965 0.9% 221 0.2%

Percentages of affected offices are calculated as a fraction of total offices estimated to incur costs under the 

proposed Dental Amalgam Rule.

Source: U.S. EPA, 2011c.

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 proposed rule would not have a 

material adverse impact on the dental office sector.

10.3.1.2 Ratio of the Proposed Rule’s Capital Costs to Total Dental Office Capital 

Assets

From the preceding analysis, EPA found that the proposed 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 proposed Dental Amalgam 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 section, 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 the next section 

(Section 10.3.1.3), examines the initial 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 

10-19 
Section 10 - Economic Impacts for the Dental Industry

compliance capital costs of the proposed 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)29 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 section. 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 Section 10.3.1.1, 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 10-11 reports the findings from this analysis, specifically the average outlay-toassets ratio values by operating size (number of chairs), and the weighted average of the outlayto-assets ratio across the number-of-chairs ranges. As with the cost-to-revenue impact analysis, 

EPA did not perform this analysis for the large institutional facilities, 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 large institutional 

facilities.

Table 10-11. Comparing Total Initial Outlay to Baseline Assets 

Initial Compliance Outlay as Percentage of Baseline Assets 

(Outlay-to-Assets, OTA)

Excluding Baseline Set-Aside Offices from Analysis 

Number of Chairs Technology-in-Place No Technology-in-Place

Low High Low High

1–2 chairs 0.1% 0.1% 2.7% 1.3%

3 chairs 0.0% 0.0% 0.8% 0.5%

4 chairs 0.0% 0.0% 0.5% 0.3%

5 chairs 0.0% 0.0% 0.3% 0.2%

29 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. 

10-20 

 
Section 10 - Economic Impacts for the Dental Industry

Table 10-11. Comparing Total Initial Outlay to Baseline Assets 

Initial Compliance Outlay as Percentage of Baseline Assets 

(Outlay-to-Assets, OTA)

Excluding Baseline Set-Aside Offices from Analysis 

Number of Chairs Technology-in-Place No Technology-in-Place

Low High Low High

6 chairs 0.0% 0.0% 0.3% 0.2%

7+ chairs 0.0% 0.0% 0.2% 0.2%

Total 0.0% 0.0% 0.7% 0.4%

Including Baseline Set-Aside Offices in Analysis 

Technology-in-place No Technology-in-place

Number of Chairs Low High Low High

1–2 chairs 0.2% 0.1% 3.7% 1.7%

3 chairs 0.0% 0.0% 0.8% 0.5%

4 chairs 0.0% 0.0% 0.5% 0.3%

5 chairs 0.0% 0.0% 0.3% 0.2%

6 chairs 0.0% 0.0% 0.3% 0.2%

7+ chairs 0.0% 0.0% 0.2% 0.2%

Total 0.0% 0.0% 0.8% 0.5%

Source: U.S. EPA, 2011c.

With baseline set-asides excluded from the analysis, the resulting initial capital costs to 

total capital assets values are low, with an average value of 0.4 percent to 0.7 percent for notechnology-in-place offices and 0 percent for the technology-in-place offices. With baseline setasides included in the analysis, the resulting initial capital costs to total capital assets values are 

low, with an average value 0.5 percent to 0.8 percent for the 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. 

10.3.1.3 Ratio of the Proposed 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 proposed 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. 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 

10-21 
Section 10 - Economic Impacts for the Dental Industry

of equipment. EPA worked with these data in several ways to develop an estimate of the steady 

state capital replacement outlay:

• 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 10-12). 

• 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 eightand 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 section of Table 10-13. 

“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 10-12. The second section of Table 10-13, “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 section of Table 

10-13, “Steady State Annual Replacement Outlay, by Equipment Life Category,” 

reports the results from this step.

Table 10-12. Composition of Dental Equipment for Six-Chair 

Office by Equipment Life

Useful Life Category

Percent of Value by Service Life Category

Major Items Percent Small Items Percent

3 $0 0.0% $19,800 21.5%

5 $52,300 21.5% $0 0.0%

10 $79,125 32.6% $72,138 78.5%

12 $6,850 2.8% $0 0.0%

15 $104,545 43.1% $0 0.0%

Total $242,820 100.0% $91,938 100.0%

Based on 6-chair office specifications from Georgetown University, 2003.

10-22 
Section 10 - Economic Impacts for the Dental Industry

Table 10-13. Initial and Annual Replacement Outlay for 

Startup Dental Office by Number of Chairs

Number of Chairs

1–2 3 4 5 6 7 8 9

Initial Outlays

Major 

items

$165,036 $185,234 $219,220 $253,207 $287,193 $321,179 $355,166 $389,152

Small items $39,082 $52,218 $68,195 $84,172 $100,149 $116,126 $132,103 $148,080

Total $204,553 $237,452 $287,415 $337,379 $387,342 $437,305 $487,269 $537,232

Initial Outlays by Equipment Life Category

3 $8,417 $11,246 $14,687 $18,127 $21,568 $25,009 $28,450 $31,891

5 $35,640 $39,897 $47,217 $54,537 $61,857 $69,177 $76,498 $83,818

10 $84,585 $101,332 $124,943 $148,554 $172,165 $195,776 $219,387 $242,998

12 $4,668 $5,225 $6,184 $7,143 $8,102 $9,061 $10,019 $10,978

15 $71,243 $79,752 $94,384 $109,017 $123,650 $138,282 $152,915 $167,548

Total $204,553 $237,452 $287,415 $337,379 $387,342 $437,305 $487,269 $537,232

Steady State Annual Replacement Outlay, by Equipment Life Category

3 $2,806 $3,749 $4,896 $6,042 $7,189 $8,336 $9,483 $10,630

5 $7,128 $7,979 $9,443 $10,907 $12,371 $13,835 $15,300 $16,764

10 $8,459 $10,133 $12,494 $14,855 $17,216 $19,578 $21,939 $24,300

12 $389 $435 $515 $595 $675 $755 $835 $915

15 $4,750 $5,317 $6,292 $7,268 $8,243 $9,219 $10,194 $11,170

Total $23,531 $27,613 $33,641 $39,668 $45,696 $51,723 $57,751 $63,778

Source: U.S. EPA, 2011c.

As the final step in this analysis, EPA compared the estimated total initial outlay for the 

proposed Dental Amalgam Rule to the estimated steady state annual replacement outlay values, 

from Table 10-13. Table 10-14 reports the results from this comparison. As shown in Table 

10-14 the values for initial compliance outlay as a percentage of replacement outlay are quite 

low, ranging from 2.2 percent to 3.5 percent, with a weighted average of 2.9 percent across all 

number-of-chair ranges.

10-23 
Section 10 - Economic Impacts for the Dental Industry

10-24 

Table 10-14. Comparing Total Initial Compliance Outlay to Steady State Annual Replacement Outlay by Number of 

Chairs (Section 10.3.1.3) 

Number of Chairs

1–2 3 4 5 6 7 8 9

Weighted 

Average

Initial compliance 

outlay

$789 $886 $886 $886 $1,345 $1,818 $1,818 $1,818

Baseline annual 

replacement outlay

$23,531 $27,613 $33,641 $39,668 $45,696 $51,723 $57,751 $63,778

Initial compliance 

outlay as percentage 

of replacement outlay

3.4% 3.2% 2.6% 2.2% 2.9% 3.5% 3.1% 2.9% 2.9%

Source: U.S. EPA, 2011c.

Table 10-15. Comparing Total Initial Compliance Outlay to Initial Outlay by Number of Chairs (Section 10.3.1.4)

 

Number of Chairs

1–2 3 4 5

6 7 8 9

Weighted

Average

Initial compliance outlay $789 $886 $886 $886 $1,345 $1,818 $1,818 $1,818

Initial outlay $204,553 $237,452 $287,415 $337,379 $387,342 $437,305 $487,269 $537,232

Initial compliance outlay 

as percentage of office 

startup costs

0.4% 0.4% 0.3% 0.3% 0.3% 0.4% 0.4% 0.3% 0.3%

Source: U.S. EPA, 2011c.
Section 10 - Economic Impacts for the Dental Industry

10.3.1.4 Economic Impact for New Sources

EPA assessed whether the proposed 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 

10-13. EPA then compared the initial compliance cost for dental offices as estimated in Section 

10.2 to these startup values. This comparison demonstrates that the amalgam separator capital 

costs would represent only 0.3 percent to 0.4 percent of the cost of starting a dental office and, 

therefore, do not pose a barrier to entry (see Table 10-15 above).

10.4 SOCIAL COST OF THE PROPOSED DENTAL AMALGAM RULE

The previous sections reviewed the estimated costs of the proposed Dental Amalgam 

Rule to dental offices and facilities and assessed the potential impact of the proposed rule on 

these offices and facilities. This section reviews the costs of the proposed Dental Amalgam 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 Section 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 seven

percent for developing present and annualized values. As described previously, the 

seven 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, three 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 

three and seven 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 proposed Dental 

Amalgam 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, 2012, and the compliance period three years 

following promulgation, in 201530. 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 

30 EPA completed its economic impact analysis assuming a promulgation date of 2012. EPA does not expect the 

results of the social cost analysis would significantly change due to a later promulgation date.

10-25 

 
Section 10 - Economic Impacts for the Dental Industry

discounted to the year of compliance and then annualized over the 20 years of rule 

compliance. These present and annualized values, which are assumed to be as of 

2015, or the first year of required compliance, are then discounted an additional three 

years to 2012, 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, based on 2007 Economic Census values expressed in 2010 dollars, 

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 Section 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, 2012, and using three

percent and seven percent discount rates. Table 10-16 summarizes these cost values for the 

proposed rule by the alternative number-of-chair distributions.

Table 10-16. Compliance Costs on a Social Cost Basis for Proposed Dental Amalgam Rule 

Annualized Cost (Millions, $2010) as of 2012, Year of Rule Promulgation

Using 3 Percent Discount Rate Using 7 Percent Discount Rate

Colorado Survey ADA Survey Colorado Survey ADA Survey

Compliance cost $43.6 $48.5 $40.0 $44.5

Source: U.S. EPA, 2011c.

10.4.2 Administrative Costs

As described above, these costs are calculated for the year of rule promulgation, 2012, as 

$833,000 at a three percent discount rate and $790,000 at a seven percent discount rate. As 

discussed in Section 1.2.3, the Control Authority could be the publicly owned treatment works 

(POTW), the state, or U.S. EPA Region. EPA estimated the annual recordkeeping costs and 

recurring costs (recordkeeping, inspections, reporting, and enforcement) for the following 

Control Authorities: 

• 403.10(e) States: 5 Control Authorities; 

• POTWs: 1,600 Control Authorities;31

• Approved Pretreatment States (minus the 403.10(e) States): 31 Control Authorities; 

and 

• U.S. EPA Regions: 9 Control Authorities.32

EPA used a labor rate estimate of $55.18/hour33 for these Control Authorities and an 

appropriate time estimate for each activity mentioned above (e.g., recordkeeping) (U.S. EPA, 

31 Estimated approved Control Authority POTWs nationwide via U.S. EPA, 2011b. 32 All states in Region 4 have approved pretreatment programs, so the state has the approval authority. 

10-26 

 
Section 10 - Economic Impacts for the Dental Industry

2011e). See DCN DA00147. 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, 2011c and 2011d). 

10.4.3 Total Social Cost 

Table 10-17 summarizes the estimated total social cost for the proposed Dental Amalgam 

Rule, including both compliance costs and administrative costs. Costs are reported by the 

alternative number-of-chair distributions and for the three and seven percent discount rates.

Table 10-17. Summary of Social Cost for Proposed Dental Amalgam Rule 

Annualized Cost (Millions, $2010) as of 2012, 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 $43.6 $48.5 $40.0 $44.5

Cost to permitting authorities $0.9 $0.9 $0.8 $0.8

Total social cost $44.5 $49.4 $40.8 $45.2

10.5 REGULATORY FLEXIBILITY ACT ASSESSMENT

As part of the cost and economic impact assessment for the proposed Dental Amalgam 

Rule, EPA considered the potential impact on small entities in the dental office business. Of key 

concern in this assessment is whether the proposed Dental Amalgam 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 $7.0 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 small dental office firms are single establishment businesses, 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 

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 in-scope dental offices 

do not process dental amalgam, and thus would be expected to incur no or limited costs under 

the proposed Dental Amalgam Rule. 

33 Metal products and machinery 150 POTW Study ($1999). EPA took the $1999 and using the Bureau of 

Employment Cost Index for State and Local Government Public Administration converted to $2010 (U.S. EPA, 

2000).

10-27 

 
Section 10 - Economic Impacts for the Dental Industry

Based on these adjustments, EPA estimated that approximately 126,800 dental offices are 

small businesses and that approximately 109,600 of these small business dental offices are in 

scope for the proposed rule and thus could incur costs under the rule. Because the number of 

small business dental offices that process amalgam is only 259 offices less than the total dental 

offices (109,862), 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 Section 10.3.1.1, which used one 

and three percent of revenue thresholds as impact measures. As described in that section, 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 10-18 summarizes the results for small entities from this analysis. 

Table 10-18. Cost-to-Revenue Impact Analysis for Small Entities 

Offices with Cost Exceeding 1 Percent of Revenue Offices with Cost Exceeding 3 Percent of Revenue

TechnologyIn-PlaceNo-Techin-Place Total PercentageTechnologyIn-PlaceNo-Techin-Place Total Percentage

Excluding Baseline Set-Aside Offices from Analysis 

33 474 507 0.5% 0 0 0 0.0%

Including Baseline Set-Aside Offices in Analysis 

243 722 965 0.9% 51 169 221 0.2%

Results are the same for both the ADA National and Colorado distributions of chairs by office.

Percentages of affected offices are calculated as a fraction of total small business offices estimated to incur costs 

under the proposed Dental Amalgam Rule.

Source: U.S. EPA, 2011c.

As shown in Table 10-18, with the baseline set-aside offices excluded from the analysis, 

EPA estimates that 507 dental offices would incur costs exceeding one percent of revenue.34

These offices represent 0.5 percent of the small business offices estimated to incur costs under 

the proposed Dental Amalgam Rule. EPA estimates that no small entities would incur costs 

exceeding three percent of revenue for the proposed rule. 

With the baseline set-aside offices included in the analysis, EPA estimates that 965 dental 

offices would incur costs exceeding one percent of revenue. These offices represent 0.9 percent 

of small business offices estimated to incur costs under the proposed Dental Amalgam Rule. 

EPA estimates that 221 dental offices would incur costs exceeding three percent of revenue, 

representing 0.2 percent of small business offices estimated to incur costs under the proposed 

Dental Amalgam 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, 

34 These findings do not vary by distribution of chairs by office.

10-28 

 
Section 10 - Economic Impacts for the Dental Industry

EPA estimates that the proposed Dental Amalgam Rule would not impose a significant impact 

on a substantial number of small entities (SISNOSE). 

10.6 REFERENCES

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. 2010a. Distribution of Dentists in the United States by Region and State, 2008. August. 

DCN DA00123. 

ADA. 2010b. 2009 Survey of Dental Practice: Income from the Private Practice of Dentistry. 

DCN DA00141.

Census. 2007. U.S. Census Bureau. Economic Census: Firm and Establishment Size. DCN 

DA00142. 

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. DCN DA00161.

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. 2011a. EPA Analysis: Part 441 Option Cost Calculations. MS ExcelTM file. Office of 

Water. Washington, DC. DCN DA00146. 

U.S. EPA. 2011b. Information Collection Request: National Pretreatment Program OMB 

Control No. 2040-0009, EPA ICR No. 0002.14 (Draft). Office of Wastewater 

Management. March. DCN DA00144. 

U.S. EPA. 2011c. Economic Analysis for the Dental Amalgam Rule. MS ExcelTM file. Office of 

Water. Washington, DC. DCN DA00145. 

U.S. EPA. 2011d. Technical Support Document for the 2010 Effluent Guidelines Program Plan. 

EPA-820-R-10-021. Office of Water. Washington, DC. DCN DA00225. 

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. 

10-29 
Section 11 - Pollutant Reduction Estimates

SECTION 11

POLLUTANT REDUCTION ESTIMATES 

The proposed rule establishes a pretreatment standard that would require removal of at 

least 99.0 percent of total mercury from amalgam discharges and best management practices 

(BMPs). EPA’s pollutant reduction methodology assumes dental offices would use the required 

BMPs in combination with 2008 ISO 11143 amalgam separators, the proposed technology basis, 

to comply with the proposed rule. 

EPA does not have office-specific discharge data for the approximately 110,000 dental 

offices potentially subject to the proposed rule. Instead, EPA has modeled the discharges of 

mercury and other metals based on nationwide estimates of amalgam fillings placed 

(restorations) and removals and did not calculate the pollutant loadings and reductions on a per 

office basis. Rather, EPA calculated average mercury (and other pollutant) loadings by dividing 

the pollutant loadings from the total number of annual procedures by the total number of dentists 

performing these procedures.35 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 sections describe the methodology 

in more detail.

11.1 NATIONAL ESTIMATE OF ANNUAL POLLUTANT LOADINGS FROM DENTAL OFFICES

This section 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. 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. Each amalgam capsule contains 450 milligrams (mg) of mercury and, on average, 

dentists use 75 percent of the capsule for the filling. The 25 percent of mercury remaining in the 

capsule is discarded as gray bag waste. Therefore, approximately 340 mg of mercury (75 percent 

of the capsule) are used per filling. Further, 9 percent of those 340 mg (31 mg) is discharged to 

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 tons of mercury 

nationwide36 in their wastewaters from restorations (U.S. EPA, 2011). Table 11-1 presents how 

mercury waste is generated at dental offices during amalgam restorations. 

35 Because this approach is based on the number of dentists, it includes those dentists both at offices and institutional 

facilities.

36 71 million restorations times 31 mg per filling.

11-1 

 
Section 11 - Pollutant Reduction Estimates

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 

Discarded as gray bag waste

Sources: U.S. EPA, 2011; 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. Based on this information, EPA estimates that approximately 97 

million amalgam removals occur each year (U.S. EPA, 2011). An average of 300 mg mercury is 

removed from each filling (Vandeven and McGinnis, 2005). EPA assumed that 90 percent of the 

removed filling (270 mg mercury) becomes part of the dental office wastewater, and the other 10 

percent is handled as dry waste and/or gray bagged. Thus, EPA estimated dental offices generate 

29 tons of mercury in their wastewaters from amalgam filling removals each year37 (U.S. EPA, 

2011). 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

97 million 

procedures 

per year

300 milligrams 

(mg) per 

removed filling

270 mg 

(90% of total mercury)

Rinsed into wastewater drain

29 tons per year from all procedures

30 mg (10% of total mercury) Dry waste disposal/gray bag waste

Sources: U.S. EPA, 2011; Vandeven and McGinnis, 2005. 

Summing the total mercury loading from the annual number of restorations and filling

removals, EPA estimated dental offices generate 31.4 tons of mercury annually as part of dental 

office wastewaters, see Table 11-3. 

37 97 million amalgam filling removals times 270 mg per removal.

11-2 

 
Section 11 - Pollutant Reduction Estimates

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

97 million 270 mg 29 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 31.4 tons

Sources: U.S. EPA, 2011a; Vandeven and McGinnis, 2005. 

11.1.2 National Estimate of Annual Baseline Mercury Discharges from Dental Offices

to POTWs

EPA estimated that within the 109,972 dental offices potentially subject to the proposed 

Dental Amalgam Rule, 13,102 offices do not place or remove amalgam and therefore do not 

generate amalgam wastewater (Section 10.1.2). Therefore, the remaining 96,870 offices 

collectively generate 31.4 tons of mercury in their wastewaters. This equates to 0.65 pounds per 

office. However, as explained earlier, these 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): 19,374 

dental offices.

• 44,461 dental offices use amalgam separators (U.S. EPA, 2011). 

• The remaining 33,035 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 52,000 dental offices without amalgam separators collectively discharge a total of 

4.4 tons of mercury to POTWs per year. The approximately 44,000 dental offices with amalgam 

separators collectively discharge approximately 63 pounds of mercury to POTWs per year. Thus, 

EPA calculated the current nationwide annual baseline loading of mercury discharged to POTWs

11-3 
Section 11 - Pollutant Reduction Estimates

from dental offices to be 4.4 tons, out of a total of the 31.4 tons originally generated (U.S. EPA, 

2011). 

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 19,374 68%

Chair-Side Traps and Vacuum Filter Only 33,035 78%

Amalgam Separator 44,461 99.0%

Total 96,870 --

Sources: U.S. EPA, 2011; 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 a small amount of zinc (Massachusetts Water Resources 

Authority, 2001). Using the mercury generation estimates in Section 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 29 tons (U.S.)

Non-Mercury 

Metals

281 mg 30 tons (U.S.)

Sources: U.S. EPA, 2011.

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 99.0 percent removal of all amalgam metals at offices with amalgam separators in 

place. Using the same methodology as described for mercury in Section 11.1.2 to calculate 

11-4 
Section 11 - Pollutant Reduction Estimates

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 

loading generated by amalgam removals as 30 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 4.6 tons, out of a total of 

32.5 tons originally generated (U.S. EPA, 2011). 

11.1.5 Total Annual Baseline Discharges to POTWs 

After accounting for existing technologies at dental offices, EPA estimated dental offices 

collectively discharge 4.4 tons of mercury and 4.6 tons of additional metals to POTWs per year 

for a total discharge to POTWs of 9.0 tons annually. 

11.2 NATIONAL ESTIMATE OF ANNUAL POLLUTANT REDUCTIONS TO POTWS ASSOCIATED 

WITH THE PROPOSED DENTAL AMALGAM RULE

EPA estimated that the 52,409 dental offices (19,374 dental offices with chair-side traps 

only and the 33,035 dental offices with chair-side traps and vacuum filters only) would install 

2008 ISO 11143 certified amalgam separators with a removal efficiency of at least 99.0 percent 

as a result of the proposed Dental Amalgam Rule. 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, 2011). This would result in reduction of total mercury 

discharges to POTWs by 4.3 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 4.5 tons. Again, EPA assumes the dissolved metal 

content to be negligible. 

Accordingly, the proposed Dental Amalgam Rule would annually reduce mercury 

discharges by 4.3 tons and other metal discharges by 4.5 tons for a total annual reduction to 

POTWs of 8.8 tons. 

11.3 NATIONAL ESTIMATE OF ANNUAL POLLUTANT REDUCTIONS TO SURFACE WATERS 

ASSOCIATED WITH THE PROPOSED DENTAL AMALGAM 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 to calculate POTW removals of each metal. As 

detailed above, at baseline and prior to implementation of the proposed rule, EPA estimated that, 

collectively, dental offices discharge 4.4 tons38 of dental mercury annually to POTWs. Based on 

the 50 POTW Study, EPA estimates that POTWs remove 90 percent of the 4.4 tons mercury 

from the wastewater. Thus, POTWs collectively discharge 880 pounds of dental mercury to 

surface waters annually.

38 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).

11-5 

 
Section 11 - Pollutant Reduction Estimates

Under the proposed Dental Amalgam Rule, over 98 percent of mercury solids currently 

discharged annually to POTWs will be removed by the installation of amalgam separators. The 

POTWs then further remove 90 percent of total mercury from the wastewater. This reduces the 

total amount of dental mercury discharged from POTWs nationwide to surface water to 14 

pounds annually. In other words, discharges of mercury to waters of the United States are 

expected to be reduced by 860 pounds per year39 as a result of the proposed rule. 

Based on the 50 POTW Study (U.S. EPA, 1982), POTWs remove the following from 

wastewater prior to discharge:

• 88 percent of total silver; 

• 79 percent of total tin; 

• 84 percent of total copper; and 

• 79 percent of total zinc.

At baseline, EPA estimates that dental offices discharge over 9,000 pounds of nonmercury amalgam metals to POTWs annually. After treatment at the POTW, POTWs 

collectively discharge 1,280 pounds of non-mercury amalgam metals to surface waters annually. 

Under the proposed Dental Amalgam Rule, the non-mercury amalgam metal discharges from 

POTWs to surface waters will be approximately 20 pounds, a reduction of 1,260 pounds. This 

results in the total reduction of amalgam metals (mercury and non-mercury) to waters of the 

United States by an estimated 2,120 pounds (U.S. EPA, 2011). 

11.4 REFERENCES

Massachusetts Water Resources Authority. 2001. Amalgam Composition in Typical Dental 

Fillings (figure). Document Control Number (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. 

U.S. EPA. 1982. Effluent Guidelines Division. Fate of Priority Pollutants in Publicly Owned 

Treatment Works. EPA 440/1-82/303. Washington, DC. (September). DCN DA00244. 

U.S. EPA. 2008. Health Services Industry Detailed Study: Dental Amalgam. EPA-821-R-08-014. 

August. DCN DA00057. 

U.S. EPA. 2011. EPA Analysis: Part 441 Option Cost Calculations. MS ExcelTM file. Office of 

Water. Washington, DC. DCN DA00146. 

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. 

39 Dissolved mercury accounts for a portion of surface water discharges, because amalgam separators do not remove 

dissolved mercury.

11-6 

 
Section 12 - Cost-Effectiveness Analysis

SECTION 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 proposed option to 

those for effluent limitation guidelines and standards (ELGs) for other industries. This definition 

includes the concepts discussed in this section. 

12.1 TOTAL INCREMENTAL ANNUALIZED COMPLIANCE COSTS

The cost-effectiveness analysis uses the estimated total annual costs of complying with 

the proposed rule. As described in Section 10.3, 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. For this proposal, EPA adjusted the value using 

the Bureau of Economic Analysis GDP Implicit Price Deflators.40 EPA calculates this adjustment 

factor as follows: 

Adjustment factor = (1981$) ÷ (2010$) = 52.270 ÷ 110.992 = 0.47093 

Table 12-1 shows the estimated annualized compliance costs converted to 1981 dollars. 

Table 12-1. Annualized Compliance Costs (Million $) 

Dental Office 

Distribution Data Source

Annualized Compliance 

Costs At Promulgation 

Year (million 2010$)

GDP Deflator 

to Convert 

2010$ to 1981$

Annualized 

Compliance Costs 

(million 1981$)

ADA Colorado Survey $43.6 0.47 $21

ADA National Survey $48.5 $23

Source: U.S. EPA, 2011a.

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 toxicitynormalized pollutant removal value for use in the cost-effectiveness analysis.41 EPA derives toxic 

weighting factors for each pollutant using chronic aquatic life criteria (or toxic effect levels) and 

human health criteria (or toxic effect levels) established for the consumption of fish. Table 12-2

lists the TWFs for the pollutants found in dental discharges. 

40 EPA typically uses the Engineering News Record Construction Cost Index. However, this approach is not 

appropriate for this proposal because the technology option does not require construction. 41 See U.S. EPA, 2011b for details on toxic weighting factors. 

12-1 

 
Section 12 - Cost-Effectiveness Analysis

Table 12-2. Toxic Weighting Factors for Pollutants in Dental 

Amalgam 

Pollutant Toxic Weighting Factor

Total mercury 117.12

Silver 16.47

Tin 0.30

Copper 0.63

Zinc 0.05

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 proposed rule for each pollutant identified in dental amalgam. 

Because this proposed rule is for indirect discharges, this estimate appropriately accounts for 

discharge reductions that occur at the publicly owned treatment works (POTW). See Section 10

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 proposed rule. Table 12-3 presents the estimate of individual and total annual 

incremental pound-equivalent removals from surface waters for the proposed rule. 

Table 12-3. Total Incremental Pound-Equivalents Removed 

from Surface Water Discharges

a

Pollutant

Incremental Removals 

from Baseline (lbs/yr) Toxic Weighting Factors

Incremental Removals 

from Baseline (lb-eq/yr)

Total mercury 863 117.12 101,048

Silver 722 16.47 11,896

Tin 331 0.30 100

Copper 167 0.63 106

Zinc 37 0.05 2

Total 113,152

Source: U.S. EPA, 2011c.

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 proposed rule is $181-$201/lb-eq ($1981). 

12-2 
Section 12 - Cost-Effectiveness Analysis

Table 12-4. PSES Cost-Effectiveness Analysis

Dental Office Distribution 

Data Source

Pre-Tax Total 

Annualized Costs 

($1981) Removals (lbs-eq)

Average CostEffectiveness ($1981)

ADA National Survey $23,000,000 113,152 $201

ADA Colorado Survey $21,000,000 113,152 $181

Source: U.S. EPA, 2011a.

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 an option to the annual pounds-equivalent removed by that 

option. For the proposed Dental Amalgam Rule, it is expressed as the average cost-effectiveness 

for the option. Average cost-effectiveness can be thought of as the increment between no 

regulation and the selected option for any given rule. The technology basis for PSES in this 

proposed rule has a cost-effectiveness ratio of $181 to $201 per lb-equivalent. This costeffectiveness 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. 2011a. Economic Analysis for the Dental Amalgam Rule. MS ExcelTM file. Office of 

Water. Washington, DC. Document Control Number (DCN) DA00145. 

U.S. EPA. 2011b. Technical Support Document for the 2010 Effluent Guidelines Program Plan. 

EPA-820-R-10-021. Office of Water. Washington, DC. DCN DA00225. 

U.S. EPA. 2011c. EPA Analysis: Part 441 Option Cost Calculations. MS ExcelTM file. Office of 

Water. Washington, DC. DCN DA00146. 

12-3 
Section 13 –Environmental Impacts of Dental Mercury Discharges

SECTION 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 

biomagnifies in aquatic food chains. For wastewater mercury discharges, the major route for 

human exposure to mercury discharged in wastewater is the consumption of mercurycontaminated 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 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%

Hg0 (unbound elemental mercury) 24.06 micrograms/liter (ppb) 0.112%

Hg+2 (ionic mercury) 54 micrograms/liter (ppb) 0.252%

Hg0 (elemental mercury bound to 

amalgam particulate)

21.360 milligrams/liter (ppm) 99.6%

Source: Stone, 2004.

While dissolved mercury (MeHg, unbound Hg0, 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 Desulfobacteraceae and Desulfovibrionaceae, 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 (WI DNR, 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 
Section 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 Section 

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. (WI DNR, 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, 2011a). 

Studies indicate that dental offices are a primary source of mercury entering POTWs. Through 

treatment, POTWs remove approximately 90 percent of dental mercury from wastewater and 

transfer it to sewage sludge. The 10 percent of dental mercury not removed by POTW treatment 

is discharged to surface water.

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 sulfur-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. This accumulation can be profound, with biomagnifications of 100,000 times 

from algae to top predators having been documented (Chin, et al., 2000). 

The neurological effects of eating fish contaminated with methylmercury are well 

documented (WI DNR, 1997). Developmental effects to fetuses, infants, children, and women of 

childbearing age are of special concern. Neurological effects from predation of methylmercury 

contaminated fish have been documented in wild populations of fish, birds, and mammals in 

many areas of the United States (WI DNR, 1997). A plausible link has been identified between 

13-2 
Section 13 –Environmental Impacts of Dental Mercury Discharges

anthropogenic sources of mercury (e.g., coal combustion) in the United States and 

methylmercury in fish. However, methylmercury in fish can also come from existing background 

concentrations of mercury, which may consist of mercury from natural sources, mercury reemitted from the oceans or soils, or mercury deposited in the United States from sources in other 

countries. Current scientific understanding of mercury’s environmental fate and transport does 

not allow quantification of how much of the methylmercury in fish consumed by the U.S. 

population is contributed by U.S. emissions, nor how much derives from natural mercury 

sources, or for that matter, from dental discharges. 

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 naturallyoccurring mercury in aquatic environments. 

13.3.2 Mercury in Biosolids

The Clean Water Act regulations at 40 CFR 503, Standards for Use and Disposal of 

Sewage Sludge, 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 4,800 pounds of dental mercury 

enters the environment as 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 facilities such as sewage sludge mono-fills or municipal 

landfills (U.S. EPA, 1999). EPA estimates that approximately 1,400 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. 

The remaining 22 percent, or 2.5 billion pounds, of sewage sludge generated annually by 

POTWs is incinerated (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). 40 CFR 503 limits the quantity of mercury and other toxic metals 

allowed per unit amount of sewage sludge prior to incineration. Concentrations of mercury 

emitted from sewage sludge incinerators must meet the National Emissions Standards for 

Hazardous Air Pollutants requirements in subpart E of 40 CFR 61. 

13.3.3 Environmental Benefits of the Proposed Dental Amalgam Rule

EPA did not perform an environmental benefits analysis of the proposed rule due to 

insufficient data about the aquatic fate and transport of dental mercury discharged by POTWs. 

13-3 
Section 13 –Environmental Impacts of Dental Mercury Discharges

However, EPA was able to assess the qualitative environmental benefits based on existing 

information. Studies have shown that decreased point source discharges of mercury to surface 

water result in lower methylmercury concentrations in fish. Moreover, several studies have 

quantified economic benefits from improved human health and ecological conditions resulting 

from lower fish concentrations of methylmercury (U.S. EPA, 2011a). The proposed requirement 

for installation of amalgam separators with 99.0 percent mercury removal efficiency will 

produce human health and ecological benefits by reducing the estimated annual nationwide 

POTW discharges of dental mercury to surface waters from 880 pounds to 14 pounds (U.S. EPA, 

2011b). In addition, the decreased discharges to POTWs will result in a decrease of mercury in 

biosolids. 

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. DCN DA00312. 

National Research Council (NRC). 2002. Biosolids Applied to Land: Advancing Standards and 

Practices. July. Division on Earth and Life Sciences. DCN DA00257. 

Stone, M.E., et al. 2002. Determination of Methyl Mercury in Dental-Unit Wastewater. Dental 

Materials 19:675-679. DCN DA00173. 

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. 1999. Biosolids Generation, Use, and Disposal in the United States. Office of Solid 

Waste. EPA 530-R-99-009. September. 

http://www.epa.gov/osw/conserve/rrr/composting/pubs/biosolid.pdf. DCN DA00303. 

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. DCN DA00256. 

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 Section 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. EPA-452/R-05-003. DCN DA00283. 

13-4 
Section 13 –Environmental Impacts of Dental Mercury Discharges

U.S. EPA. 2009. Targeted National Sewage Sludge Survey: Sampling and Analysis Technical 

Report. DCN DA00299. 

U.S. EPA. 2011a. Literature Review of the Impacts of Mercury from Dental Amalgam in 

Wastewater. Office of Water. Washington, DC. DCN DA00148. 

U.S. EPA. 2011b. EPA Analysis: Part 441 Option Cost Calculations. MS ExcelTM file. Office of 

Water. Washington, DC. DCN DA00146. 

WI DNR (Wisconsin Department of Natural Resources). 1997. Wisconsin Mercury Sourcebook.

DCN DA00202. 

13-5 
Section 14 - Non-Water-Quality Impacts

SECTION 14

NON-WATER-QUALITY IMPACTS

Eliminating or reducing one form of pollution may cause other environmental problems. 

Sections 304(b) and 306 of the Clean Water Act require EPA to consider non-water-quality 

environmental impacts (including energy requirements) associated with effluent limitation 

guidelines and standards (ELGs). To comply with these requirements, EPA considered the 

potential impact of amalgam separators and best management practices (BMPs) on energy 

consumption, air pollution, and solid waste generation. EPA anticipates that the proposed Dental 

Amalgam Rule will produce minimal non-water-quality impacts. The Administrator has 

determined that these very minimal impacts are acceptable. 

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 proposed rule. As described in Section 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 essentially all of the excess amalgam from the 

wastewater. Most separators rely on gravity or the suction of the existing vacuum system to 

operate and do not require an additional electrical power source. As a result, EPA expects 

operation of an amalgam separator would pose negligible additional energy requirements on the 

existing vacuum pump. 

While the vendor data used to support the proposed rule did not include incremental 

energy requirements for an amalgam separator, EPA is aware that 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. Based on this evaluation, EPA concluded there will be no 

significant non-water-quality impacts associated with the energy requirements for the proposed 

rule.

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 carried by wastewater to the publicly 

owned treatment works (POTW), where approximately 90 percent is removed from the 

wastewater into the POTW sludge; the sludge may be land applied, disposed of in landfills or 

mono-fills, or incinerated. The proposed rule is expected to increase the use of amalgam 

14-1 
Section 14 - Non-Water-Quality Impacts

separators nationwide—EPA expects over 50,000 dental offices to install amalgam separators to 

comply with the proposed rule (see Table 10-2). Currently, just under 45,000 dental offices have 

separators installed (see Table 10-2). EPA expects the collected amalgam that is no longer 

discharged to the POTW will be recycled via the spent separator canisters. The operation and 

maintenance requirements associated with the amalgam separator compliance option will 

promote recycling as the primary means of amalgam waste management. EPA expects the 

proposed rule will not create additional solid waste, but will instead change how dental amalgam 

is handled. Nationally, EPA expects less dental amalgam will partition to the POTW wastewater 

sludge, leading to reductions in the amount of mercury currently land-applied, landfilled, or 

released to the air during incineration. Instead, it will be collected in separator canisters and 

recycled. Based on this evaluation of solid waste generation, EPA concluded that there will be a 

reduction in non-water-quality impacts associated with solid waste generation as a result of the 

proposed 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 proposed rule will not pose any increases in air pollution. EPA 

concluded that there will be no significant non-water-quality impacts associated with air 

emissions as a result of the proposed Dental Amalgam Rule.

14.4 REFERENCES

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. 

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. 

14-2 
Section 15- Implementation

SECTION 15 

IMPLEMENTATION 

This section provides guidance to Control Authorities, such as publicly owned treatment 

works (POTWs) in implementing Effluent Limitation Guidelines and Standards (ELGs) for the 

Dental Category. 

15.1 IMPLEMENTATION DEADLINE FOR EXISTING SOURCES

For existing sources, EPA proposes a compliance date of three years after the effective 

date of the final rule. Section 307(b)(1) of the Clean Water Act (CWA) provides that categorical 

pretreatment standards “shall specify a time for compliance not to exceed three years from the 

date of promulgation.” See also 40 CFR 403.6(b). In proposing a compliance date for existing 

sources subject to this proposed rule, EPA considered several factors. First, EPA considered the 

burden on Control Authorities (POTWs with approved Pretreatment Programs) of implementing 

this rule on an industry consisting of approximately 110,000 dental offices, many of which are 

small businesses. EPA expects that POTWs will need to develop and implement new strategies 

and programs for managing the enforcement and compliance of these pretreatment standards 

given that the number of possibly affected facilities is approximately 10 times the total number 

of dischargers currently regulated under any categorical pretreatment standard. EPA expects that 

POTWs will need time to conduct outreach to dental offices subject to the proposed rule. 

Moreover, EPA envisions that dental offices may use the entire three-year period to come into 

compliance with the numeric standard (presumably using amalgam separators) and implement 

the required best management practices (BMPs). 

15.2 IMPLEMENTATION DEADLINE FOR NEW SOURCES

For new sources, the compliance deadline is governed by EPA’s regulation at 40 CFR 

403.6(b), which provides that “New Sources shall install and have in operating condition, and 

shall ‘start-up’ all pollution control equipment required to meet applicable Pretreatment 

Standards before beginning to Discharge. Within the shortest feasible time (not to exceed 90 

days), new Sources must meet all applicable Pretreatment Standards.” Table 15-1 presents the 

implementation deadline for existing and new sources of dental amalgam discharges.

Table 15-1. Compliance Time for Dental Offices Potentially Subject to the Proposed Rule

Dental Office Requirement Deadline

Existing Office that Dischargers to 

the Sewer

Comply with PSES Three years after the effective date 

of any final rule.

New Office that Discharges to the 

Sewer

Comply with PSNS When discharging begins.

15.3 REPORTING REQUIREMENTS

The following describes the steps a dental office would take to comply with the reporting 

requirements associated with the proposed rule:

15-1 
Section 15- Implementation

1. A dental office (or facility) should determine if any of its operations are potentially 

subject to the proposed rule. 

i. Does the office discharge to a sewer or directly to a POTW? If not, the office in 

not potentially subject to the proposed rule and does not have any obligations. 

ii. Does the office exclusively practice one or more of the following dental 

specialties: oral pathology, oral and maxillofacial radiology, oral and 

maxillofacial surgery, orthodontics, periodontics, or prosthodontics? If yes, the 

office is not potentially subject to the dental amalgam proposed rule. 

2. If an office or facility is subject to the proposed rule, it should determine whether it 

places or removes amalgam. If it does neither (except in limited emergency 

circumstances), it would certify that to the Control Authority. 

i. If an office or facility is subject to the proposed rule and places or removes 

amalgam, it will need to comply with the general reporting requirements, which 

include submission of two one-time reports: a 90-day compliance report and a 

baseline monitoring report. The latter must be submitted within 180 days of the 

effective date of any final rule. The office or facility will also have to submit an 

annual certification. 

15-2 
Section 16 - Updates to General Pretreatment Standards 

(40 CFR 403)

SECTION 16

UPDATES TO GENERAL PRETREATMENT STANDARDS 

(40 CFR 403)

In addition to the pretreatment standards for dental offices, EPA is proposing to amend 

selected parts of the General Pretreatment Regulations to simplify oversight requirements for the 

approximately 110,000 dental offices subject to this rule. When EPA promulgates categorical 

industrial pretreatment standards, as defined in 40 CFR 403, affected dischargers are referred to 

as Categorical Industrial Users (CIUs). The number of dental offices subject to the proposed 

Dental Amalgam Rule is approximately 10 times the current number of CIUs. EPA recognized 

that regulatory oversight of this increased number of CIUs would need to be very different from 

regulating the current number of CIUs. Using the existing regulatory framework to enforce 

categorical pretreatment regulation on this industry would require an increase in available local, 

state, and federal resources; and EPA does not expect such efforts to result in greater 

environmental benefit. EPA is focusing on providing technical means to reduce administrative 

burden to dentists and Control Authorities, while still providing a clear understanding of who is 

affected and what they are expected to do, and achieving the projected pollutant reductions. 

16.1 PROPOSED CHANGES TO THE GENERAL PRETREATMENT STANDARDS

EPA is proposing a new classification of CIU specifically tailored to the Dental Office

Effluent Limitation Guidelines and Standards rule: “Dental Industrial User” (DIU). EPA is 

proposing that such users not be subject to the oversight requirements for Significant Industrial 

Users, or SIUs (i.e., control mechanism issuance requirement, annual inspection, and sampling 

requirements). Rather, EPA is proposing to allow Control Authorities to focus their oversight 

efforts on those dental offices that fail to meet the compliance requirements of the DIU.

Under the proposed rule, a dental amalgam discharger is given the option of complying 

with monitoring and reporting requirements in 40 CFR 441.60, which are tailored for dental 

amalgam dischargers, in lieu of the otherwise applicable monitoring and reporting requirements 

in 40 CFR 403. If a dental amalgam discharger complies with the special monitoring and 

reporting requirements in Section 441.60, the remaining Part 403 requirements, and the 

applicable pretreatment standards (PSES or PSNS), then the Control Authority may treat the 

dental amalgam discharger as a DIU. The DIU must maintain compliance in order to retain its 

DIU status.

If the dental office does not meet the requirements to be classified as a DIU, under the 

proposed rule, the Control Authority would be required to classify the dental amalgam discharger 

as an SIU as defined in 40 CFR 403.3(v). As an SIU, the Control Authority would be required to 

conduct the oversight duties applicable to SIUs as described in 40 CFR 403.8(f). 

EPA notes that the proposed changes to 40 CFR 403 to create the DIU classification are 

changes that the Control Authority may adopt at its discretion. The changes to Part 403 provide 

program flexibility and are not required to be incorporated into the state or POTW’s Pretreatment 

Program. However, for Control Authorities to designate dental offices as DIUs, the state and 

16-1 
Section 16 - Updates to General Pretreatment Standards 

(40 CFR 403)

POTW Pretreatment Program would need to incorporate the proposed changes into their legal 

authority under 40 CFR 403.8(f)(l). 

16.2 RESPONSIBILITIES OF THE CONTROL AUTHORITIES

As described in Section 1.2.3, the Control Authority (either the POTW or state/EPA 

Region) is responsible for permitting, sampling, and inspecting industrial users that discharge to 

POTWs. The proposed rule would require that a Control Authority evaluate, at least once per 

year, whether an industrial user previously determined to be a DIU still meets the criteria for 

treatment as a DIU under 40 CFR 441.60. EPA anticipates that this evaluation will primarily 

involve the Control Authority’s verification that the certification has been submitted by the 

dental office to document their continued eligibility for DIU status. 

16.2.1 Noncompliance

In accordance with 40 CFR 403.8(f)(2)(viii)(F), a dental amalgam discharger that is 

classified as a DIU would be in significant noncompliance if it fails to provide any required 

report within 45 days of the due date, or if the Control Authority inspects the office and finds the 

office is not in compliance with 40 CFR 441.60. Upon discovery that a dental practice is not in 

compliance with regulations at 40 CFR 441.60 (either reporting requirements, Part 403, or Part 

441 PSES/PSNS requirements), the Control Authority must initiate enforcement in accordance 

with its approved pretreatment program to return the dental amalgam discharger into compliance. 

To continue to treat the dental office as a DIU, the Control Authority would need to verify and 

find, through an inspection, that the dental amalgam discharger has returned to full compliance 

with the criteria in Part 441.60. If, within 90 days, the Control Authority inspects, verifies, and 

finds that the dental amalgam discharger has returned to full compliance with Part 441.60, then 

the dental amalgam discharger would remain a DIU. The 90-day compliance deadline is 

consistent with other portions of 40 CFR 403 (e.g., significant noncompliance, compliance report 

deadlines, 90-day report after effective dates of categorical standards), and provides both the 

dental amalgam discharger and Control Authority with an incentive to provide a timely return to 

compliance. If the dental amalgam discharger has not returned to compliance within 90 days of 

the initial noncompliance, the Control Authority could no longer treat the dental amalgam 

discharger as a DIU, and the dental amalgam discharger would become an SIU. Control 

Authorities are required to oversee SIUs, which includes inspecting and sampling each SIU 

annually, reviewing the need for a slug control plan, and issuing a permit or equivalent control 

mechanism with a duration not to exceed five years (40 CFR 403.8(f)1)(iii) and (2)(v) and 

403.10(f)(2)(i)). 

16.2.2 Classification of Dental Offices as Non-Significant Categorical Industrial Users 

(NSCIU)

EPA is not proposing to prohibit a Control Authority from finding that a dental office or 

other facility may qualify as an NSCIU on an individual basis. State Approval Authorities and 

POTW Control Authorities with the legal authority to implement the NSCIU classification may 

find that one or more of their Dental Office CIUs may qualify as an NSCIU. However, since its 

promulgation in 2005, many state Approval Authorities and POTW Control Authorities have not 

adopted regulations to implement the NSCIU classification. EPA believes that the DIU 

classification, tailored for this single categorical pretreatment standard, while comparable to the 

16-2 
Section 16 - Updates to General Pretreatment Standards 

(40 CFR 403)

NSCIU classification, would be preferable because it would significantly reduce the Control 

Authority’s burden in complying with the oversight requirements that would otherwise apply. 

16-3 
Section 17- Glossary And List of Acronyms

SECTION 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 limitation 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.

CESQG – Conditionally Exempt Small Quantity Generators.

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 POTW's submission for its pretreatment program (§403.3(t)(1)) 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. 

17-1 
Section 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.

DIU – Dental Industrial User. New classification of CIU specifically tailored to the National 

Categorical Pretreatment Standards for the Dental Category. 

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. 

17-2 
Section 17- Glossary And List of Acronyms

MOU – Memorandum of Understanding. 

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.

NSCIU – Non-Significant Categorical Industrial User.

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 

17-3 
Section 17- Glossary And List of Acronyms

they provide and the economic activities in which they are engaged. SIC codes often denote a 

facility's primary, secondary, tertiary, etc. economic activities.

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. 

Wastewater – For this document, water emanating from dental facility. 

17-4