*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 1 of 103

EO12866_DentalEffluentGuidelinesandStandards RIN 2040-AF26 NPRM FRN_20140430

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 403

40 CFR Part 441

[EPA-HQ-OW-2012 FRL-]

RIN 2040-AF26

Effluent Limitation Guidelines and Standards for the Dental Category

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed Rule.

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

Act (CWA) for discharges of pollutants into publicly owned treatment works (POTWs) from 

existing and new dental practices that discharge dental amalgam. The proposal would require 

dental practices to comply with requirements for controlling the discharge of mercury and other

metals in dental amalgam into POTWs based on the best available technology or best available 

demonstrated control technology. Specifically, the requirements would be based on the use of 

amalgam separators and a few Best Management Practices. Amalgam separators are a practical, 

affordable and readily available technology for capturing mercury and other metals before they 

are discharged into sewers. EPA is also proposing to amend selected parts of the General 

Pretreatment Regulations (40 CFR Part 403) to streamline oversight requirements for the dental 

sector. EPA expects compliance with this proposed rule would reduce the discharge of metals to 

POTWs by at least 8.8 tons per year, about half of which is mercury. EPA estimates the annual 

cost of the proposed rule would be $44 to $49 million.

DATES: Comments on today‟s proposed rule must be received on or before [insert date 60 days 

after publication in the Federal Register]. Under the Paperwork Reduction Act, comments on the 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 2 of 103

information collection provisions must be received by the Office of Management and Budget on 

or before [insert date 30 days after publication in the Federal Register]. EPA will conduct a 

public hearing on xxxxx at xxxx. For information on the location of the public

hearing, see SUPPLEMENTARY INFORMATION.

ADDRESSES: The public hearing will be held at xxxxxx, Washington, DC.

Submit your comments, identified by Docket No. [insert docket number] by one of the 

following methods:

http:www.regulations.gov: Follow the on-line instructions for submitting comments.

Email: OW-Docket@epa.gov, Attention Docket ID No. [insert docket number].

Mail: Water Docket, U.S. Environmental Protection Agency, Mail code: 4203M, 1200 

Pennsylvania Ave., NW., Washington, DC 20460. Attention Docket ID No. [insert 

docket number]. Please include a total of 3 copies. In addition, please mail a copy of 

your comments on the information collection provisions to the Office of Information and 

Regulatory Affairs, Office of Management and Budget (OMB), Attn: Desk Officer for 

EPA, 725 17th St. NW., Washington, DC 20503.

Hand Delivery: Water Docket, EPA Docket Center, EPA West Building Room 3334, 

1301 Constitution Ave., NW, Washington, DC, Attention Docket ID No. [insert docket 

number] . Such deliveries are only accepted during the Docket‟s normal hours of 

operation, and special arrangements should be made for deliveries of boxed information 

by calling 202-566-2426.

Instructions: Direct your comments to Docket No [insert docket number]. EPA's policy is that 

all comments received will be included in the public docket without change and may be made 

available online at http://www.regulations.gov, including any personal information provided, 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 3 of 103

unless the comment includes information claimed to be Confidential Business Information (CBI) 

or other information whose disclosure is restricted by statute. Do not submit information that 

you consider to be CBI or otherwise protected through www.regulations.gov or e-mail. The 

www.regulations.gov website is an “anonymous access” system, which means EPA will not 

know your identity or contact information unless you provide it in the body of your comment. If 

you send an e-mail comment directly to EPA without going through www.regulations.gov your 

e-mail address will be automatically captured and included as part of the comment that is placed 

in the public docket and made available on the Internet. If you submit an electronic comment, 

EPA recommends that you include your name and other contact information in the body of your 

comment and with any disk or CD-ROM you submit. If EPA cannot read your comment due to 

technical difficulties and cannot contact you for clarification, EPA may not be able to consider 

your comment. Electronic files should avoid the use of special characters, any form of 

encryption, and be free of any defects or viruses. 

Docket: All documents in the docket are listed in the www.regulations.gov index. A detailed 

record index, organized by subject, is available on EPA‟s website at 

http://water.epa.gov/scitech/wastetech/guide/dental/index.cfm. Although listed in the index, 

some information is not publicly available, e.g., CBI or other information whose disclosure is 

restricted by statute. Certain other material, such as copyrighted material, will be publicly 

available only in hard copy. Publicly available docket materials are available either 

electronically in www.regulations.gov or in hard copy at the Water Docket in the EPA Docket 

Center, EPA/DC, EPA West, Room 3334, 1301 Constitution Ave., NW, Washington, DC. The 

Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 4 of 103

legal holidays. The telephone number for the Public Reading Room is 202-566-1744, and the 

telephone number for the Water Docket is 202-566-2426.

FOR FURTHER INFORMATION CONTACT:

Damon Highsmith, Engineering and Analysis Division, telephone: 202-566-2504; e-mail: 

highsmith.damon@epa.gov.

SUPPLEMENTARY INFORMATION: 

Regulated Entities

Entities potentially regulated by this action include:

Category Example of Regulated Entity North American Industry 

Classification System Code

Industry

A general dentistry practice or 

large facility where mercury 

amalgam is placed or removed.

621210

States

Where they are the Control 

Authority.

221320

Municipalities

POTWs and other municipally

owned facilities that receive 

pollutants from dental offices. 

221320

This section is not intended to be exhaustive, but rather provides a guide for readers 

regarding entities likely to be regulated by this proposed action. Other types of entities that do 

not meet the above criteria could also be regulated. To determine whether your facility would be 

regulated by this proposed action, you should carefully examine the applicability criteria listed in 

§441.10 and the definitions in §441.20 of the rule and detailed further in Section V of this 

preamble. If you still have questions regarding the proposed applicability of this action to a 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 5 of 103

particular entity, consult one of the persons listed for technical information in the preceding FOR 

FURTHER INFORMATION CONTACT section.

How to Submit Comments

The public may submit comments in written or electronic form. (See the ADDRESSES 

section above.) Electronic comments must be identified by the docket no. [insert docket number] 

and must be submitted as a WordPerfect, MS Word or ASCII text file, avoiding the use of 

special characters and any form of encryption. EPA requests that any graphics included in 

electronic comments also be provided in hard-copy form. EPA also will accept comments and 

data on disks in the aforementioned file formats. Electronic comments received on this notice 

may be filed online at many Federal Depository Libraries. No confidential business information 

(CBI) should be sent by e-mail.

Supporting Documentation

The rule proposed today is supported by a number of documents including:

Technical and Economic Development Document for Proposed Effluent Limitation 

Guidelines and Standards for the Dental Amalgam Category (TEDD), Document No.xxx.

This document summarizes the technical and economic analysis described in today‟s notice. This 

document and additional records are available in the public record for this rule and on EPA‟s 

website at http://water.epa.gov/scitech/wastetech/guide/dental/index.cfm. They are available in 

hard copy from the National Service Center for Environmental Publications (NSCEP), U.S. 

EPA/NSCEP, P.O. Box 42419, Cincinnati, Ohio 45242-2419, telephone 800-490-9198, 

http://epa.gov/ncepihom .
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 6 of 103

Overview

The preamble describes the terms, acronyms, and abbreviations used in this notice; the 

background documents that support these proposed regulations; the legal authority for the 

proposed rules; a summary of the options considered for the proposal; background information; 

and the technical and economic methodologies used by the Agency to develop these proposed

regulations. This preamble also solicits comment and data on specific areas of interest.

Table of Contents

I. Legal Authority

II. Purpose and Summary of Proposed Rule

III. Background

IV. Description of the Dental Industry

V. Summary of Data Collection

VI. Wastewater Characteristics, Dental Office Configurations and Technology 

Options

VII. Scope/Applicability 

VIII. Subcategorization

IX. Proposed Regulation

X. Technology Costs

XI. Economic Impacts

XII. Pollutant Reductions to POTWs and Surface Waters

XIII. Cost Effectiveness

XIV. Environmental Assessment

XV. Non-Water Quality Environmental Impacts Associated with the Proposed 

Technology Basis

XVI. Implementation and Proposed Changes to General Pretreatment Regulations in 

Part 403

XVII. Statutory and Executive Order Reviews

I. Legal Authority

EPA is proposing this regulation under the authorities of sections 101, 301, 304, 306, 

307, 308, and 501 of the Clean Water Act (CWA), 33 U.S.C. §§ 1251, 1311, 1314, 1316, 1317, 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 7 of 103

1318, 1342 and 1361 and pursuant to the Pollution Prevention Act of 1990, 42 U.S.C. § 13101 et 

seq.

II. Purpose and Summary of Proposed Rule

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

wastewater treatment plants) are working toward the goal of reducing discharges of mercury to 

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

entering POTWs. According to the 2002 Mercury Source Control and Pollution Prevention 

Program Final Report prepared by the National Association of Clean Water Agencies 

(NACWA), dentists are the main source of mercury discharges to POTWs. A study funded by 

the American Dental Association (ADA) estimated in 2003 that 50% of mercury entering 

POTWs was contributed by dental offices (see DCN xxxx). Mercury is discharged in the form 

of dental amalgam when dentists remove old amalgam fillings from cavities, and from excess 

amalgam removed when a dentist places a new filling.

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

human health. Mercury is such a concern that on November 6, 2013 the United States agreed to 

become a party to the Minamata Convention on Mercury, a new multilateral environmental 

agreement that addresses specific human activities which are contributing to widespread mercury 

pollution. The agreement acknowledges that one activity contributing to mercury discharges to 

the environment is mercury in dental amalgam. The Convention included eight measures for 

consideration in phasing down the use of mercury in dental amalgam including promoting the 

use of best environmental practices in dental facilities to reduce releases of mercury and mercury 

compounds to water and land. Nations that abide by the Convention are required to include at 

least two of the eight measures to address dental amalgam.
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 8 of 103

EPA estimates that across the United States 4.4 tons of mercury from waste dental 

amalgam are collectively discharged into POTWs. Mercury at POTWs frequently partitions to 

the sludge, the solid material that remains after wastewater is treated. Mercury from amalgam 

can then make its way into the environment through the incineration, landfilling, or land 

application of sludge or through surface water discharge. 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.

Today‟s proposed pretreatment standards would control mercury discharges to POTWs 

by requiring dentists to reduce their discharge of dental amalgam to a level achievable through 

the use of the best available technology (amalgam separators and the use of Best Management 

Practices). In order to simplify compliance with, and enforcement of the numeric reduction 

requirements, the proposed rule would allow dentists to demonstrate compliance through the 

proper use of amalgam separators rather than through discharge monitoring. Removing 

concentrated sources of mercury from the environment opportunistically, such as through lowcost amalgam separators at dental offices (average annual cost per dental office: $700), is a 

common sense solution to managing mercury that would otherwise be dispersed to air, land, and 

water.

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

Regulations (40 CFR Part 403) in order to streamline permitting and oversight requirements specific 

to the dental sector. The number of dental offices that would likely be subject to national 

pretreatment standards is approximately ten times the current number of Categorical Industrial Users 

(CIUs). The proposed changes to 40 CFR Part 403 reflect EPA‟s recognition that the current 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 9 of 103

regulatory framework needs to be adjusted for the effective implementation and enforcement of these 

pretreatment requirements on the dental industry. When categorical pretreatment requirements apply 

to an industry, it triggers certain oversight requirements. While other industries subject to categorical 

pretreatment requirements typically consist of ten to hundreds of facilities, the dental industry 

consists of approximately 100,000 facilities, making oversight of this large number of facilities 

subject to categorical pretreatment standards much more challenging. 

III. Background

A. 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 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 10 of 103

(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. 

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 based on best professional judgment 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 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 (i.e., 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 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 11 of 103

the Act and ; and (3) non-conventional pollutants, those that are neither conventional nor toxic

(e.g., ammonia-N, formaldehyde, and phosphorus).

B. Effluent Guidelines and Standards Program

Effluent limitations guidelines and standards are technology-based regulations that are 

developed by EPA for a category of dischargers. These regulations are based on the 

performance of control and treatment technologies. The legislative history of CWA section 

304(b), describes the need to press toward higher levels of control through research and

development of new processes, modifications, replacement of obsolete plans and processes, and 

other improvements in technology, taking into account the cost of controls. Congress also 

directed that EPA not consider water quality impacts on individual water bodies as the guidelines 

are developed. See Statement of Senator Muskie (Oct. 4, 1972), reprinted in Legislative History 

of the Water Pollution Control Act Amendments of 1972, at 170. (U.S. Senate, Committee on 

Public Works, Serial No. 93-1, January 1973.)

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

standards applicable to indirect dischargers (discharges to publicly owned treatment works or 

POTWs). The standards relevant to this rulemaking are summarized here.

1. Best Available Technology Economically Achievable (BAT)

BAT effluent limitations 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 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 12 of 103

as the Administrator deems appropriate. The Agency retains 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, nonconventional, and priority pollutants). In establishing NSPS, EPA is directed 

to take into consideration the cost of achieving the effluent reduction and any non-water quality 

environmental impacts and energy requirements.
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 13 of 103

3. Pretreatment Standards for Existing Sources (PSES)

Pretreatment standards apply to discharges of pollutants to publicly owned treatment 

works (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 at 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 effluent limitations guidelines and standards 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 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 14 of 103

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) 

(EPA 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) (``section 502(11) [of the CWA] defines `effluent limitation' as `any 

restriction' on the amounts of pollutants discharged, not just a numerical restriction.'').

C. The National Pretreatment Program, 40 C.F.R. part 403

The General Pretreatment Regulations of 40 C.F.R. part 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 it has not been 

approved. The term Approval Authority describes the party with responsibility to administer the 

National Pretreatment Program- 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 C.F.R. § 

403.3(f)]. An approved pretreatment program is comprised of legal authorities, procedures, 

funding, local limits, enforcement response plan, and the list of significant industrial users, 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 15 of 103

together 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 more commonly referred to as Industrial 

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

D. State and local requirements

Currently, at least 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 discharges1. 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% to 99%. A full list of jurisdictions with mandatory separator requirements can be found in 

the Technical and Economic Development Document (TEDD) of the proposed rulemaking. 

Later in this document, EPA estimates costs and economic impacts of today‟s proposed rule. 

 

1 New Mexico has a similar program that is scheduled to go into effect in 2015.
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 16 of 103

In order to do so, EPA needed to estimate baseline compliance, or those dental offices that 

already have amalgam separators installed, and therefore would incur lower costs and impacts. In 

order to estimate baseline compliance, EPA distributed the number of dental offices shown in 

Table IV-1 of section IV by state2, based on the 2007 Economic Census. EPA assumes 100% 

compliance in the 12 states that require amalgams separators. For states without mandatory 

programs, EPA assumed that 20 percent of dentists have voluntarily installed amalgam 

separators. As a result, EPA estimates approximately 40% of dental offices, nationally, have 

amalgam separators installed.

E. 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. 

F. 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 

 

2

Puerto Rico, the Virgin Islands, Pacific Islands and Tribal Nations are not included in this analysis.
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 17 of 103

stream. In 2007, ADA added the use of amalgam separators to their BMPs. [See DCN].

In late 2010, ADA‟s Board of Directors adopted nine principles upon which ADA 

supported National Pretreatment Standards for dental facilities. See DCN.

IV. Description of the Dental Industry

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

(NAICS 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 HMO medical centers. They can provide either comprehensive preventive, 

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

According to the 2007 Economic Census, there were 127,057 U.S dental offices owned 

or operated by 121,048 dental firms.

3 Only 2% of all dental firms were multi-unit with the vast 

majority being single-unit. The growth of the number of dental offices has remained steady over 

the past decade with an average increase of 1% per year.

The industry includes mostly small businesses with an estimated 99.8% of all offices 

falling below the SBA size standard ($7 million in annual revenue). Average revenues for offices 

were estimated at $739,280 per year with an average of 6.50 employees per establishment.

According to ADA data, approximately 80% of the dental industry engages in general 

dentistry. Approximately 20% are specialty dentists such as periodontics, orthodontics, 

radiology, maxillofacial surgery, endodontists, or prosthodontics. 

One way to categorize dental offices is based on the number of chairs in each facility. 

 

3 A firm is a business organization, such as a sole proprietorship, partnership, or corporation.
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 18 of 103

The 2007 Economic Census does not provide information on the distribution of dental offices by 

the number of chairs in each office. However, two studies, the ADA National Study and a 

Colorado Study, demonstrate distribution of dentist offices by number of chairs. EPA used these 

two sources of data to correlate the number of chairs per office to the revenue range of dental 

offices. EPA averaged the correlation of these two studies. The results are reported in table IV1

Table IV-1: Number of Dental Offices by Number of Chairs

Number of Chairs

Number of Offices by Chair Size

ADA Survey Colorado Survey Average

1-2 chairs 13,694 10,701 12,197

3 chairs 47,698 27,822 25,835

4 chairs 32,102 27,976

5 chairs 29,388 15,694 15,194

6 chairs 9,399 12,047

7+ chairs 19,079 14,143 16,611

Total 109,859 109,861 109,860

Dentistry may also 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 130 dental institutional facilities exist nationwide. 

EPA currently lacks a central database on reported discharges from dental offices/clinics. 

Often, EPA looks to information in the Toxic Release Inventory (TRI) and Discharge Monitoring 

Report (DMR) databases to gather information on industrial discharges. However, no dental 

offices/clinics (SIC 8021) reported to TRI for 2009. A facility is exempt from TRI reporting if it 

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

which for mercury and mercury compounds is 10 pounds per year. Further, EPA has not found 

any DMR data indicating that any dental offices discharge directly to waters of the U.S. 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 19 of 103

Therefore, EPA is not proposing effluent limits for direct dischargers.

4

V. Summary of Data Collection

In developing today‟s proposed rule, EPA primarily used data previously collected for its 

Health Services Detailed Study including information submitted in public comments on the 

study. EPA also collected information and data through outreach to a number of stakeholders. 

The following describes EPA‟s outreach and additional data sources for today‟s proposed rule.

[see DCN]

A. Health Services Industry Detailed Study on Dental Amalgam

In 2008, EPA published its Health Services Industry Detailed Study on Dental Amalgam. 

In the study, EPA compiled information on mercury discharges from dental offices, BMPs, and 

amalgam separators. For amalgam separators, EPA examined the frequency with which they 

were used; their effectiveness in reducing discharges to POTWs; and the capital and annual costs 

associated with their installation and operation. EPA also conducted a POTW pass-through 

analysis on mercury for the industry. Today‟s proposed rule relies heavily on data collected for 

the Study (including information submitted in public comments on the Study). 

B. Environmental Council of the States

EPA participated in several meetings with the Quicksilver Caucus (QSC) of the 

Environmental Council of States. From QSC, EPA collected information on implementing 

mandatory amalgam separator programs at the state level, mandatory program language, and 

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

on efficiency standards for amalgam separators. [see DCN]

 

4 EPA recognizes that some dental facilities may discharge to a septic system. Today‟s rule does not apply to such 

discharges.
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 20 of 103

C. Environmental Groups

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 impacts of discharges of dental 

amalgam to the environment. In Spring 2011, the coalition submitted a letter listing its suggested 

BMPs for today‟s proposed rule. See DCN.

D. American Dental Association

EPA met with the American Dental Association (ADA) in 2010 and 2011. ADA 

submitted data to EPA on its principles for addressing mercury discharges from dentists, the 

proportions of specialties in the industry, the geographic distribution of dentists, financial 

characteristics of the industry, and operating characteristics of the industry. See DCN.

E. National Association of Clean Water Agencies (NACWA)

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

on publicly owned treatment works (POTWs). NACWA provided EPA information on its 

members‟ experiences with handling mercury pollution from dental facilities, implementing 

pretreatment programs for dental facilities, and its experiences implementing pretreatment 

standards for industries with similar characteristics to the dental sector. NACWA also provided 

EPA with information on the burden to permitting authorities that would be associated with 

implementing a dental amalgam pretreatment standard under the existing requirements in Part 

403. [see DCN]

F. Amalgam Separator Manufacturers

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

separator manufacturers. The purpose of the meetings was to understand how amalgam 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 21 of 103

separators work, limitations of the technology, manufacturers‟ distribution methods, installation 

requirements, capital and operation and maintenance costs, operation and maintenance 

requirements, effectiveness, equipment lifetime, amalgam disposal or recycling practices, 

manufacturing capacity, and installation trends. 

G. Air Force Study

In anticipation of today‟s proposed rule, the United States Air Force‟s Dental Evaluation 

and Consultation Service compiled a synopsis of commonly used amalgam separator systems. 

The synopsis describes whether or not the separator is ISO 11143 certified, the installation 

requirements, the design capacity, maintenance requirements for each model, the availability of 

recycling services by the manufacturer, size, price, and warranty details. EPA incorporated this 

data into the technology cost analysis. The synopsis can be found in the TEDD for this rule. 

VI. Wastewater Characteristics, Dental Office Configurations, and Technology Options 

A. Wastewater Sources and Wastewater Characteristics

Dental amalgam consists of approximately fifty percent mercury by weight. Mercury is 

the only metal that is in the liquid phase at room temperature, and bonds well with powdered 

alloy. This contributes to its durability in dental amalgam. The other half of dental amalgam is 

usually composed of 35% silver, 9% tin, 6% copper and small amounts of zinc, indium, and 

palladium [see DCN#, Massachusetts Water Resources Authority, 2001]. Sources of mercury 

discharges generally occur in the course of two categories of activities. The first category of 

discharges may occur in the course of treating a patient, such as during the placement or removal 

of a filling. When filling a cavity, dentists overfill the tooth cavity so that the filling can be 

carved to the proper shape. The excess amalgam is typically rinsed into a chair-side drain, or 

suctioned out of the patient‟s mouth. In addition to filling new cavities, dentists also remove old 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 22 of 103

cavity restorations that are worn or damaged. Removed restorations also may be rinsed into the 

chair-side drain or suctioned out of the patient‟s mouth. The second category of mercury 

discharges occur in the course of activities 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 present opportunities for mercury from dental amalgam 

to be discharged. For additional information, see Section III.

B. Dental Office Configurations 

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. Chair side traps and vacuum pump 

filters generally remove 40 to 80 percent of dental amalgam particles from the wastewater 

stream. Offices with multiple chairs typically share the vacuum lines between chairs. 

Accordingly, this limits the locations for installation of control and treatment technologies. 

Controls may be installed: at or near each individual chair; within the vacuum system piping; at a 

central location upstream of the vacuum pump; or at the exit of the air/water separator portion of 

the vacuum system. Physical office and building configurations may pose additional 

considerations, such as space limitations, 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. 

C. Control and Treatment Technologies and Best Management Practices

As described previously, the discharge of mercury from dental amalgam occurs when 

dental amalgam enters the chair-side drain, or is suctioned from the patient‟s mouth. The 

wastewater then travels through the dental facility‟s vacuum system. EPA identified two major 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 23 of 103

technologies that intercept dental amalgam at this point, before it is discharged from the dental 

office and flows to the POTW: separators and ion exchange. EPA also identified several Best 

Management Practices which, when employed along with the use of the technologies discussed 

below, further reduce the discharge of dental amalgam from activities not directly related to the 

placement or removal of dental amalgam. 

1) Amalgam Separators

An amalgam separator is a device designed to remove solids from dental office 

wastewater. The amalgam separator is placed at some 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 facility‟s vacuum to draw 

wastewater into the separator. However, the separation of solids from the wastewater and the exit 

of the wastewater from the separator will vary by design of the separator. 

Practically all amalgam separators on the market today use sedimentation processes. The 

high specific gravity of amalgam allows effective separation of amalgam from suspension in 

wastewater. Baffles or tanks can reduce the speed of the wastewater flow, allowing more 

amalgam particles to settle out. After the solids settle, the wastewater is either pumped out, 

decanted during servicing, or is pulled through the separator. Sedimentation-based separators 

may be preferable over other separation technologies for their operational simplicity. 

Some amalgam separators may combine filtration with separation. Different types of 

filtration units can be employed to remove additional amalgam particles. The amalgam separator 

may also be designed to operate horizontally where wastewater is drawn into one side of the 

separator, filtered, and then exits the opposite side of the separator. This type of separator is 

designed to be completely replaced once it reaches its design solids holding capacity. In addition 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 24 of 103

to combined separation and filtration units, EPA is aware of at least one type of separator that 

utilizes centrifugation. A centrifuge-based separator spins the water so that the heavier amalgam 

particles are forced to the sides of the separator.

A few amalgam separators combine sedimentation (with or without filtration) with ion 

exchange in the same unit. This type of separator additionally includes a chelating agent or 

proprietary resin. This type of separator often requires special cleaning or additives to maintain 

efficiency. 

The typical amalgam separator will operate in one of two ways. A two-chambered 

separator is a design consisting 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 separator from the top of the 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 separator. 

The wastewater, less the solids retained by the separator, then continues through the vacuum 

system and is eventually discharged from the dental office and to the sewer. The second common 

separator 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, remains in the separator for some time, 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 25 of 103

and allows solids to settle. For either design, when the filtration cartridge or the separator itself 

reaches the designed solids retention capacity, it must be replaced. 

The vast majority of amalgam separators on the market today have been evaluated for 

their ability to meet the International Organization for Standardization Standard for Dental 

Amalgam Separators 

(http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=42288). 

This voluntary standard setting organization established a standard for measuring amalgam 

separator efficiency by evaluating the retention of amalgam mercury using specified test 

procedures in a laboratory setting. It also includes requirements for instructions for use and 

operation and maintenance. In order to obtain the ISO certification, a separator must achieve 95 

percent removal or greater of total mercury. Based on EPA‟s evaluation of a range of amalgam 

separators as described above that meet the ISO standard and that are currently on the market, 

(DCN xxx), certified separators obtain a median of 98.8 percent total mercury removal 

efficiency. When existing chair side traps and vacuum pump filters are used upstream of the 

amalgam separators, the combined treatment system can achieve total mercury removal rates 

exceeding 99 percent.

EPA is proposing to include certain operation, maintenance, and inspection activities that 

have the greatest impact on the ability of an amalgam separator to achieve its performance as 

certified. 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 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 26 of 103

effect on vacuum suction, it is important that the unit be checked periodically, and if necessary, 

serviced. 

Solids collected by the amalgam separator may be a combination of dental amalgam, 

biological material from patients, and any other solid material sent down the vacuum line. 

Amalgam separator manufacturer instructions should be followed for servicing amalgam 

separators and for handling separator waste. Some amalgam separator manufactures also offer 

waste management services. Examples of services provided include ensuring that waste collected 

by the separator is handled according to state and local requirements, and providing necessary 

compliance documentation for the facility‟s recordkeeping requirements. In the event that these 

services are not employed, the facility should dispose of amalgam waste in accordance with state 

and local requirements.

Amalgam separators are widely used in dental offices. Most amalgam separators are 

compatible with both wet and dry vacuum systems, and with both large and small dental offices5. 

As explained in Section III, currently at least 12 states and 19 localities have implemented 

mandatory programs to reduce dental mercury discharges. All of these programs require the use 

of amalgam separators. Further, many dental offices in states or localities without mandatory 

programs have voluntarily installed dental amalgam separators and the ADA recommends their 

use as part of its “Best Management Practices for Amalgam Waste” (2007). As described in 

section III, EPA estimates that 40 percent of dental offices currently employ amalgam separators. 

2) Polishing to Remove Dissolved Mercury from Wastewater

 

5 This does not mean all types of separators are compatible at a given dental office. For example,

an amalgam separator that relies on filtration technology may not be compatible with a dry 

vacuum system in place. 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 27 of 103

Mercury in dental amalgam is present in both the suspended and dissolved form. The vast 

majority (>99.6 percent) is suspended (Vandeven and McGinnis, 2005). 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 wastewater treatment system 

added after the amalgam separator for the purpose of removing dissolved mercury. 

Dissolved mercury has a tendency to bind with other chemicals, resulting in a charged 

complex. Ion exchange is the process that separates these charged amalgam particles from the 

wastewater. Ion exchange does not rely on physical settling of particles, and can remove very 

small amalgam and ionic mercury particles. This technology may be preferable over 

sedimentation (with or without filtration) alone because dissolved mercury is removed by this 

process. For example, ion exchange might be useful in municipalities that have concentration 

limits on mercury (McManus, 2003). EPA is not aware of any state regulations that require ion 

exchange. 

For ion exchange to be most effective, the incoming wastewater to be treated must first 

have the solids removed. Then the wastewater needs to be oxidized in order for the resin or 

mercury capturing material to capture the dissolved mercury. Therefore, ion exchange will not 

be effective without first being preceded by a solids collector. 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. Dental offices needing to employ polishing would likely need to add a separate ion 

exchange unit following the amalgam separator to remove additional mercury from the waste 

stream.
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 28 of 103

As explained above, ISO certification testing is based on an evaluation of the removal of 

total mercury in a laboratory setting and does not differentiate removal for the suspended and 

dissolved forms6. In order to better understand the reductions in dissolved mercury that can be 

achieved with the addition of ion exchange as polishing, EPA reviewed available data on the 

performance from actual installations of ion exchange units in addition to amalgam separators in 

dental offices. EPA found the use of polishing is limited to just a handful of dental offices. EPA 

identified only one study of polishing systems, and has not identified any further data pertaining 

to the performance of polishing. This one study evaluated the additional efficacy associated with 

polishing at two dental facilities in response to sanitation district concerns over mercury 

discharges. In both cases, the polishing systems were installed after the amalgam separators but 

prior to discharge into the treatment plant‟s collection system. While a reduction was observed in 

the final effluent mercury after the polishing system was installed, preliminary EPA Region 8 

audits showed the total additional mercury reductions were typically on the order of 0.5 percent 

[DCN xxxxx]. This is not surprising since, as indicated above, dissolved mercury contributes 

such a small portion to the total amount of mercury in dental amalgam. It is unclear whether any 

solid mercury was converted to dissolved mercury, and additional monitoring data are not yet 

available. 

The capital costs of the polishing system, as a stand-alone system, are approximately 4 

times that of the amalgam separator; the costs for chemical use, regenerating the resin, filter 

replacement, and other operational costs were not reported. Further, EPA is uncertain whether 

 

6

In some cases, the ISO testing results include ranges of dissolved mercury in the effluent.
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 29 of 103

typical dental buildings have adequate space to install the holding tanks needed to oxidize the 

waste before treatment, as well as space for the polishing equipment itself. 

3) Best Management Practices

EPA considered what BMPs reflect the best available technology economically 

achievable or best available demonstrated control technology – the standards applicable to 

existing and new sources subject to categorical pretreatment standards. After this review, EPA is 

proposing to include certain operation, maintenance, and inspection practices as part of the 

technology basis for today‟s proposed rule. These practices have the greatest impact on the 

ability of an amalgam separator to achieve its performance as certified.

EPA is also proposing to require two BMPs to control mercury discharges that would not 

be captured by an amalgam separator. Bleach and other corrosive cleaners can solubilize bound 

mercury. If corrosive cleaners are used to clean vacuum lines that lead to an amalgam separator, 

the line cleaners may solubilize any mercury that the separator has captured, leading to increased 

mercury discharges. Therefore, EPA proposes to require line cleaners that do not contain bleach, 

and are of neutral pH. 

Flushing scrap amalgam (contact and non-contact), including but not limited to dental 

amalgam from chair-side traps, screens, vacuum pump filters, dental tools, or collection devices 

into drains that do not have a solids collecting device present additional opportunities for 

mercury to be discharged from the dental office. Therefore, EPA proposes to include a BMP that 

prohibits flushing scrap dental amalgam into any drain that is not connected to an amalgam 

separator. 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 30 of 103

VII. Scope/Applicability 

As mentioned in the previous section, EPA has not identified dental offices/clinics 

discharging directly to waters of the U.S. Because EPA has very limited information on any 

direct discharge of dental amalgam, EPA is not proposing effluent limitations guidelines and new 

source performance standards for direct dischargers at this time.

As such, EPA is proposing to apply this rule to wastewater discharges to POTWs from 

offices where the practice of dentistry is performed, including but not limited to institutions, 

permanent or temporary offices, clinics, mobile units, home offices, and facilities, and including 

dental facilities owned and operated by Federal, State or local governments. EPA is not 

proposing to include wastewater discharges from dental facilities where the practice of dentistry 

consists exclusively of one or more of the following dental specialties: oral pathology, oral and 

maxillofacial radiology, oral and maxillofacial surgery, orthodontics, periodontics, or 

prosthodontics. As described in the TEDD, these specialty practices do not engage in the practice 

of restorations or removals, and are not expected to have any discharges of dental amalgam. 

VIII. 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 take 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 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 31 of 103

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 dental office, specialty practices, and unusual configurations 

that may be found at very large offices such as clinics and universities. EPA proposes that 

establishing formal subcategories is not appropriate for the Dental Amalgam 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 that already have 

regulatory programs for controlling discharges of dental amalgam have been largely successful 

without subcategorization.

IX. Proposed Regulation

A. PSES Options Selection

Section VII discussed the technologies identified to control amalgam discharges from 

dental offices. As explained there, EPA identified two basic technologies, amalgam separators 

and polishing. For the reasons explained below, EPA determined separators plus polishing is not

“available” as that term is used in the Clean Water Act. 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 32 of 103

EPA has identified one technology that is available and demonstrated – amalgam 

separators. EPA has further identified Best Management Practices that would ensure the 

effectiveness of the amalgam separator technology and would reduce discharges of dental 

amalgam not captured by an amalgam separator. Therefore, EPA has developed a regulatory 

option based on proper operation and maintenance of amalgam separators that achieve a 98.8% 

reduction of total mercury from amalgam process wastewater with Best Management Practices. 

Compliance with the numeric pretreatment standard for new and existing sources could be met 

by installation and proper operation and maintenance of an amalgam separator certified to meet 

98.8% 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. EPA finds that the proposed technology basis is “available” as that 

term is used in the Clean Water Act because it is readily available and feasible for all dental 

offices. ADA recommends its dentists use the technology on which this rule is based (i.e., 

amalgam separators and Best Management Practices). 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 this is a low cost technology with an approximate average annual cost of $700 per 

office. EPA‟s economic analysis analyzes these costs in relation to the overall income of the 

regulated entities and shows that this proposed rule is economically achievable (See Section XI). 

Finally, EPA also examined the non-water quality environmental impacts of the proposed rule 

and found them to be acceptable. See Section XIV, “Non Water Quality Environmental 

Impacts”.
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 33 of 103

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

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

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

to truly assess the efficacy of polishing or its availability of ion exchange for nationwide use. 

EPA‟s current information suggests that polishing only achieves incremental removals over the 

BAT selected technology of less than one half percent of total mercury. While even very small 

amounts of mercury have environmental effects, EPA is not certain that there is a significant

difference in the performance between the two technologies. Further, EPA estimates that the 

capital costs of amalgam separators and polishing are at least 4 times that of amalgam separators 

alone (see TEDD). Finally, EPA is uncertain whether existing dental offices have adequate space 

to install polishing controls. These factors lead EPA to find that polishing is not “available” as 

that term is used in the Clean Water Act. As a result, EPA did not select amalgam separators 

followed by polishing as the technology basis for today‟s proposed rule. EPA solicits data on the 

costs, performance, affordability, and availability of polishing in combination with amalgam 

separators. 

B. Pollutants of Concern and Pass Through

Of the dental amalgam constituents, mercury is of greatest concern to human health 

because it is a persistent, bioaccumulative, toxic chemical and can bioaccumulate three to ten 

times across each trophic level of the food chain. 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. 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 34 of 103

EPA finds that the technologies considered for control of amalgam solids will be 

similarly effective on other metals contained in dental amalgam because these metals are in a 

solids form, and the separation technology is designed to remove solids. Therefore any controls 

established for the reduction of mercury discharges will similarly reduce the discharge of other 

metals contained in amalgam. As such, EPA focused its consideration of regulated pollutants on 

mercury.

C. 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 for 

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 when considering 

the establishment of categorical pretreatment standards, EPA compares the percentage of the 

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

pollutant removed by facilities meeting BAT 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 BPT/BAT effluent limitations. In this 

manner, EPA can ensure that the combined treatment at indirect discharging facilities and 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 35 of 103

POTWs is at least equivalent to that obtained through treatment by a direct discharger, while also 

considering the capability of the POTW. 

In the case of this proposed rulemaking, 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). The 50 POTW study presents data on 

the performance of 50 POTWs achieving secondary treatment in removing toxic pollutants. 

Results of this study demonstrate POTWs remove 90% of total mercury found in wastewater. 

EPA has received data from targeted studies performed by NACWA and ADA that indicate a 

POTW can remove 95% of total mercury. However, these studies reflect the performance of best 

performing POTWs, as opposed to the 50 POTW Study which reflects nationwide POTWs.

Consequently, for today‟s proposal, EPA maintains a POTW percent removal rate of 90% for its 

nationwide pass-through analysis. In comparison, indirect dischargers using today‟s proposed 

technology will remove 98.8% or more total mercury prior to discharge. Therefore, EPA 

concludes mercury passes through7and is today proposing requirements to control its discharge. 

D. Requirements

Today‟s proposed rule would establish a pretreatment standard that would require 

removal of at least 98.8% of total mercury from amalgam discharges and Best Management 

Practices. One way affected dental offices would be able to meet the standard would be to use,

and properly operate and maintain, a dental amalgam separator certified to achieve at least 98.8% 

 

7

For all the metals contained in dental amalgam, EPA‟s record demonstrates that these pollutants would similarly 

pass through as defined above. See DCN xxx for POTW removal estimates for the other metals.
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 36 of 103

reduction of total mercury according to the 2008 ISO 11143 standard, to perform certain Best 

Management Practices, and to certify to this effect. Another way affected dental offices would 

be able to meet the standard would be to certify that they do not install or remove amalgam. 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 that 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 wastestreams, and the difficulty in

obtaining a sample that represents only dental amalgam discharges. Moreover, amalgam 

separators are an easy to use, low cost technology. Dental offices that elect to not use an 

amalgam separator must meet the proposed numeric limit and would be subject to the oversight 

and compliance requirements for requirements for indirect discharges subject to national 

pretreatment requirements. 

 In selecting an amalgam separator that meets the requirements of today‟s proposed 

pretreatment standards, dentists should 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. 

Today‟s proposal would subject all dentists (except those specialists as described in 

Section V) to categorical pretreatment requirements. EPA recognizes that some in-scope dentists
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 37 of 103

do not apply or remove dental amalgam. However, EPA, in consultation with pretreatment 

authorities, has been unable to determine a publically available source of information that 

differentiates dental offices on the basis of whether or not dental amalgam may be reasonably 

expected to present. As such, today‟s 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 will not install or remove amalgam (not including infrequent emergency 

treatment as discussed below). This would fulfill their obligations under today‟s proposed rule. 

As a point of clarification, if they then 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 Best Management Practices in today‟s proposed rule8.

Also, EPA does not want to penalize existing dental offices or institutional dental 

facilities that have already installed amalgam separators voluntarily ahead of EPA‟s proposed 

rulemaking 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 less than 

today‟s proposed standard. For example, some states require dental offices to employ amalgam 

separators that are certified to remove 95 percent total mercury. EPA does not want to propose a 

rule that would require existing separators that still have a remaining useful life to be retrofitted

with new separators, both because of the additional costs incurred by dental facilities that moved 

ahead of EPA‟s proposed requirements to install a treatment technology and because of the 

additional solid waste that would be generated by disposal of the existing separators. Therefore,

EPA is proposing that, as long as they continue to properly operate and maintain existing 

 

8 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.
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 38 of 103

separators, comply with Best Management Practices, 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 ten years because it appears to be 

a conservative estimate of the useful life of the existing equipment. However, if prior to that 

time, the currently installed separator needs to be replaced, these facilities would need to install 

and operate an amalgam separator that meets a removal efficiency of 98.8%. 

EPA requests comment on this proposed regulatory scheme. In particular, EPA seeks 

comment on its approach for addressing offices where no dental amalgam is placed or removed

except in limited emergency circumstances, and its approach for offices that have already 

installed an amalgam separator.

 

E. PSNS Option Selection

As previously noted, under Section 307(c) of the CWA, new sources of pollutants into 

POTWs must comply with standards which 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 is today proposing 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 different from those identified for existing sources. 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 39 of 103

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 is proposing to establish NSPS that 

are the same to those proposed for PSES. 

EPA is not proposing 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. 

X. Technology Costs 

This section summarizes EPA‟s approach for estimating compliance costs, while the 

TEDD provides detailed information on the methodology. EPA‟s cost methodology assumes 

dental offices would use the required BMPs in combination with 2008 ISO 11143 amalgam 

separators on the market today to comply (See DCN xxx). EPA categorized all of the costs as 

either capital costs 9(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. All final cost estimates are expressed in terms of 2010 dollars. 

EPA estimated compliance costs associated with today‟s proposal using data collected 

through EPA‟s Health Services Industry Detailed Study (August 2008) [xxxxxx], a review of the 

 

9

See Section X and the Economic Section of the Technical Development Document for 

information on how EPA annualized costs.
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 40 of 103

literature, and information supplied by vendors. EPA‟s cost estimates represent the incremental 

costs for a dental office to comply with today‟s proposed rule. For costing purposes, EPA 

differentiated dental offices by those that already use amalgam separators and those that do not. 

EPA recognizes that some fraction of dental offices subject to today‟s proposed rule may 

not place or remove amalgam and has proposed a provision that would allow them to submit a 

one-time baseline monitoring report. Such dental offices would be exempted from this rule so 

long as they do not place or remove amalgam. Should the status of the 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 441.10. EPA 

estimates the costs associated with this one-time only report to be $22. 

In general, one approach that EPA may take 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 a fair amount of 

facility specific technical and financial data. In this case, EPA would need such data for 

approximately 110,000 dental offices estimated to be subject to this 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 the affected facilities and calculate costs for each model 

facility. EPA can then determine how many of the affected facilities are represented nationally 

by each model facility to represent the full universe of affected facilities.

A. Methodology for Developing Model Dental Office Costs

EPA used the model approach to estimate costs for facilities that place or remove 

amalgam for today‟s proposal. The model facility approach used in this effort involved 

calculating compliance costs for each of the size classes of dental offices described in section IV
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 41 of 103

of this preamble. In other words, EPA developed compliance costs for 6 models based on the 

numbers of chairs in an office. The ranges for each model are as follows: 1 to 2 chairs, 3 chairs, 

4 chairs, 5 chairs, 6 chairs, 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. This is discussed separately in the next section. 

EPA developed two sets of costs for each model: one for facilities that do not use an 

amalgam separator and one for facilities that do. For those that do not use an amalgam separator, 

EPA estimated capital costs and operation and maintenance costs. Capital costs include purchase 

of the separator and installation. Recurring costs include replacement of the cartridge, and 

operation and maintenance costs. A summary of costs for dental offices that do not currently use 

amalgam separators may be found in Tables IX(A)(a), and IX(A)(b).

Table IX(A)(a): Summary of One Time Model Facility Costs ($2010) for Dental Offices 

that Do Not Currently Use Amalgam Separators

Cost Element Number of chairs in the model dental office

1 or 2 3, 4, or 510 6 7+

Separator Purchase $502 $599 $1,058 $1,531

Installation $250 $250 $250 $250

 

10

 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.
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 42 of 103

Table IX(A)(b): Summary of Annual Model Facility Costs ($2010) for Dental Offices 

that Do Not Currently Use Amalgam Separators

Cost Element Number of chairs in the model dental office

1 or 2 3, 4, or 511 6 7+

Replacement Parts $195 $219 $430 $647

O&M including recycling $216 $216 $216 $216

For those facilities that already have an amalgam separator, EPA calculated costs for 

certain additional recurring operation and maintenance associated with the amalgam separator 

compliance option in today‟s proposal. Recurring costs include replacement of the cartridge and 

operation and maintenance costs. A summary of these costs may be found in Table IX(A)(c). 

This is a conservative approach to costing however, because some of these facilities would 

presumably continue to operate and maintain the separators that they have already chosen or 

been required to install.

Table IX(A)(c): Summary of Annual Model Facility Costs ($2010) for Dental Offices 

that Currently Use Amalgam Separators

Cost Element Number of chairs in the model dental office

1 or 2 3, 4, or 512 6 7+

Replacement Parts $98 $110 $215 $324

 

11

 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.

12

 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.
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 43 of 103

O&M including recycling $116 $116 $116 $116

In assessing the long term costs of rule compliance for these model facilities (those with 

and without existing separators), EPA estimated that amalgam separators would have a service 

life of 10 years, at which time the amalgam separators would need to be replaced. For the 

purposes of cost estimates for today‟s proposal, EPA assumed that all offices regardless of the 

original technology in-place would incur the full cost of purchasing amalgam separators at the 

time of reinstallation. However, because various modifications needed by the office for initial 

amalgam separator installation would have already been completed, EPA has projected that 

amalgam separators replaced beyond year 10 would be installed at one-half of the cost of the 

original installation. For example, EPA assumed plumbing modifications for initial installation 

would cost $250 per office, but that replaced equipment would cost $125 to install. EPA

assumed that dental offices would continue to incur recurring expenses such as O&M in the 

same way as described for the initial installation.

Finally, all dental offices subject to today‟s proposed rule will also have reporting 

requirements and BMP requirements. EPA also included reporting costs for one-time 

preparation of a baseline report and initial compliance report and recurring costs associated with 

preparation of an annual certification statement. Section VII describes the BMPs in today‟s 

proposal. EPA projects that there will be no incremental costs associated with these 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. 

C. Methodology for Developing Costs for Institutional Facilities
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 44 of 103

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. Scaling the information on costs 

for the 10 chair model facility to a 15 chair operation using a straight ratio yields costs at these 

institutional facilities at 1.5 times the costs estimated for the largest chair range shown in Table 

IX(A)(a) and Table IX(A)(b). These costs are likely overstated as they do not reflect 

opportunities the largest offices may have to share costs,

13 and they do not assume any 

economies of scale. EPA solicits comment and data regarding EPA‟s analysis of clinics and 

institutional facilities.

XI. Economic Impact Analysis

This section summarizes EPA‟s assessment of the costs and impacts of the proposed 

pretreatment standards on the regulated industry. 

A) Social Cost Estimates

As described earlier in Section VIII of today‟s preamble, EPA is proposing PSES and 

PSNS based on a widely available technology, amalgam separator, and employment of BMPs.

Section IX provides a detailed explanation of how EPA estimated compliance costs for model 

dental offices. As described there, EPA developed compliance costs for 6 models based on the 

numbers of chairs in an office. The ranges for each model are as follows: 1 to 2 chairs, 3 chairs, 

 

13 For example, multiple offices located in a single building or complex may be able to share plumbing, vacuum 

systems, and may be able to install a larger separator rather than each office having its own separator.
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 45 of 103

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 institutional facilities such as clinics 

and universities. 

For each model facility, EPA estimated compliance costs for dental offices that currently 

use a separator, those that do not have a separator in place, and those that certify that they do not 

place or remove amalgam. For those that don‟t currently use a separator, EPA estimated 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, annual purchases of amalgam cartridges, and recycling), and

as reporting costs. For those that use a separator (approximately 40% of dental offices as 

reported in Section IV), EPA estimated O&M costs and reporting costs only. As applicable, EPA 

annualized the capital costs over a 20-year period at a discount rate of 3 percent14 and summed 

these costs with the O&M and reporting costs to determine an annual compliance cost estimate 

for each model facility. In order to develop a national estimate of social costs15 based on these 

model facilities, EPA estimated the number of dental offices represented by each model facility. 

As explained in Section IV, EPA estimated the number of dental offices based on data from the 

2007 Economic Census16 describing the number of establishments in the Offices of Dentists 

NAICS (621210), and their annual revenue. Because reported establishments were described by 

 

14 See the Technical and Economic Development Document (TEDD) for the reported analyses using a 7% discount 

rate

15Costs of the rule, from the standpoint of cost to society, which includes compliance costs, and cost to the 

permitting authorities. Social costs would also incorporate any adjustment based on a quantity demand response to a 

change in price driven by a price change due to cost pass-through to consumers. For this analysis, EPA is not able 

to demonstrate an observable change in price for dental services, therefore no observable change in amount of visits 

(quantity demanded). Therefore EPA makes no adjustment to social costs based on a change in quantity.

16 EPA adjusted the 2007 Economic Census revenue values to reflect 2010 dollars. 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 46 of 103

their annual revenue and not number of chairs (the basis of model compliance costs), EPA used 

data from two surveys, a Colorado survey and an ADA survey, to correlate the estimated number 

of chairs per office to the revenue range of dental offices. Because EPA used two different data 

sources, results are presented as a range. Details of the relationship between chairs and revenue 

can be found in the Technical and Economic Development Document (TEDD).

To estimate nationwide social costs, EPA multiplied the estimated total annualized costs 

of rule compliance for each model facility by the estimated number of dental offices represented 

by that model (i.e. with the indicated number of chairs and with/without existing amalgam 

separators). EPA also accounted for some in-scope dental offices that may not place or remove 

amalgam and assigned them costs only for a one-time baseline monitoring report. EPA then 

summed the values for each chair range over the number of chair ranges to yield the total 

estimated compliance cost. 

Similarly, EPA calculated costs for institutional facilities by multiplying the compliance 

cost for its model institutional facility by the number of estimated institutional facilities indicated 

in Section IV. Lastly, EPA estimated costs for control authorities for administering the Dental 

Amalgam Rule. Details of this cost analysis can be found in the TEDD. See Table XI(A) for 

EPA‟s estimate of nationwide annualized costs for each chair range represented by EPA‟s model 

facilities as well as EPA‟s estimate of total nationwide annualized costs for today‟s proposed rule. 

Table XI(A): Summary of Total Estimated Social Costs (millions of 2010 dollars)

Table XI(A): Total Annualized Social Costs by Number of Chairs (millions of 2010 dollars)

Total Annualized Costs by Chair Size2

Number of Chairs Colorado Survey ADA Survey

1-2 chairs $3.4 $4.4

3 chairs $9.5 $16.3 4 chairs $11.0

5 chairs $5.4 $14.8 6 chairs $4.7

7+ chairs $9.5 $12.8
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 47 of 103

Large Dental Facilities $0.1 $0.1

Cost to control authorities $0.6 $0.6

Total Annualized Social Costs $44.2 $49.1

2EPA assumed that initial capital outlays and initial incurrence of ongoing compliance expenses would 

occur in the third year following rule promulgation. EPA assumed that the amalgam separator 

technology would have a service life of 10 years, and used a 20-year analysis period to allow for onetime replacement of capital equipment 10 years following the initial installation. A 3% discount rate was 

used for the analysis reported in this table, see the Technical and Economic Development Document 

(TEDD) for the analysis with a 7% discount rate. 

B) Economic Impact Methodologies

1. Dental Office Impact Methodologies

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. In addition, EPA chose to examine 

the financial impacts of the proposed regulatory option 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 and (2) Ratio of the 

Proposed Rule‟s Capital Costs to Annual Dental Office Capital Replacement Costs. 

EPA did not conduct a traditional closure analysis for this proposed rule because EPA 

does not have detailed data on baseline financial conditions of dental offices. Also, 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 as is the case in the dental industry. 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). 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:
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 48 of 103

These low revenue offices could be single-dentist and/or part-time businesses that 

provide services as a subcontractor on an independent fee-for-service basis, such as 

dental hygiene, in general service dental offices that are 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 a 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. On the other hand 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 these very low revenue offices could be non-profit groups which 

provide pay-as-you-can or free services to a low-income populations. In this case, these 

small businesses may be viable enterprises because they receive in-kind donations not 

counted as revenue, e.g., services of a practicing dentist. 

Alternatively, these low revenue offices may be non-viable as for-profit businesses, if 

they are attempting to operate as general service dental practices. This is based on EPA‟s 

assessment (see Ratio of Proposed Rule Capital Costs to Total Dental Office Capital 

Replacement Costs, below) that 1-2 chair offices would incur pre-rule capital 

replacement costs of approximately $23,500 per year. This costs represents all or a 

substantial fraction of annual revenue of the business in the below-$25,000 revenue 

range. Accordingly, these businesses may not be operating viably as for-profit general 

service dental offices. 

As such, EPA could consider these offices to be the equivalent of baseline closures as 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 49 of 103

traditionally accounted for in cost and economic impact analysis for effluent guidelines 

rulemakings. As a result and in light of the uncertainty here, EPA analyzed the impacts twice: (1) 

excluding dental offices that could represent baseline closures and (2) including all offices in the 

analysis. EPA solicits comment for additional information on these low revenue dental offices. 

a) Cost-to-Revenue Analysis

To provide an assessment of the impact of the rule on dental offices, EPA used a cost-torevenue analysis as is standard practice for Effluent Limit Guidelines when looking at impacts to 

small businesses. The cost-to-revenue analysis compares the total annualized compliance cost of 

each regulatory option with the revenue of the entities. It is also used under the Regulatory 

Flexibility Act to determine if a rule has the potential to have a significant impact on a 

substantial number of small entities. EPA apportioned all dental offices into Economic Census 

revenue ranges. Using the relationship between revenue and number-of-chairs previously 

developed, each revenue range was assigned to a number-of-chairs category which determined 

its annual costs. EPA looked at whether all, some, or none of the offices in each revenue range 

would exceed the 1% or 3% threshold (to signal the potential for significant impact), and 

summed across chair-size categories to assess impact to the industry. To incorporate the 

discussion of low revenue dental offices described in Section C.1 above, this analysis is 

conducted twice: (1) excluding dental offices that could represent baseline closures and (2) 

including all offices in the analysis.

b) Ratio of the Proposed Rule‟s Capital Costs to Total Dental Office Capital Assets 

This ratio examines the initial spending on capital costs of compliance in relation to the 

baseline value of assets on the balance sheet of dental office businesses. EPA assumes a low 

ratio implies limited impact on dental offices‟ ability to finance the initial spending on capital 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 50 of 103

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. EPA relied on data from Risk Management 

Association (RMA)17 to estimate the average asset-to-sales ratio in each number-of-chairs 

category for the dental office sector. This ratio was then applied to the revenue range/number-ofchairs categories to find an asset value for the minimum (reported as low in table XI(C)(1)(b))

and maximum (reported as high in table XI(C)(1)(b)) revenue values for that number-of-chairs 

category. EPA used these baseline assets by number-of-chairs category as the denominator for 

the ratio. Total proposed rule compliance costs, as described in Section X.B above, were 

assigned to each number-of-chairs category as the numerator for the ratio. To incorporate the 

discussion of low revenue dental offices described in Section X.C.1 above, this analysis is 

conducted twice: (1) excluding dental offices that could represent baseline closures, and (2) 

including all offices in the analysis. This analysis assumes a minimum revenue value of $5,000 

for the lowest revenue range to prevent division by zero. 

The RMA data contains the limitation that it may not be fully representative of all dental 

offices, because it only represents dental offices that are successful borrowers. So offices that are 

not financially healthy may be underrepresented in the RMA data. This would tend to understate 

EPA‟s finding of impacts.

c) Comparison of the Proposed Rule‟s Capital Costs to Annual Dental Office Capital 

Replacement Costs

EPA also compared the initial spending on capital costs of compliance associated with 

today‟s proposed rule to the estimated capital replacement costs for a dental office business (e.g., 

 

17 Risk Management Association 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.
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 51 of 103

computer systems, chairs, x-ray machines, etc.). The capital replacement costs represent a value 

that dental offices may reasonably expect to spend in any year to replace and/or upgrade dental 

office capital equipment. EPA assumes 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. 

However, because EPA expects that annual dental office capital replacement would be smaller 

than total dental office capital assets, this ratio is likely to result in a higher value than the 

previous ratio. Because this ratio is based on a different data source, it provides an independent 

check that abstracts from the limitations of the RMA data.

EPA used data from Safety Net Dental Clinic Manual, prepared by the National Maternal 

& Child Oral Health Resource Center at Georgetown University (See DCN xxx). This study 

examines data describing the equipment needs and costs for starting a dental practice for a range 

of different number-of-chairs including information on the life of the dental equipment. EPA then 

used this data to estimate capital replacement costs, accounting for the total value of equipment 

purchases for different numbers of chairs, and the composition of purchases by equipment life 

category. EPA used these replacement capital costs by number-of-chairs as the denominator for 

the ratio. Total proposed rule compliance costs, as described in Section X.B above, were 

assigned to each number-of-chairs as the numerator for the ratio. 

Because the data is for starting a dental clinic instead of a dental practice, EPA is taking 

comment to solicit additional information on equipment needs and costs for starting a dental 

practice including information on the life of the dental equipment. See the TEDD for details on 

this analysis. 

C) Results of Impact Analysis
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 52 of 103

1. Results of Dental Office Impact Analyses

a) Cost-to-Revenue Analysis Results

Following the methodology outlined in X1.B, EPA estimated the occurrence of 

annualized compliance costs exceeding the one and three percent of revenue thresholds for the 

proposed option twice: (1) excluding dental offices that could represent baseline closures, and 

(2) including all offices in the analysis. 

Table X(C)(1)(a) summarizes the results from this analysis. As shown there, under either 

scenario, over 99% of dentists would incur annualized compliance costs of less than 1% of 

revenue. With baseline set-asides excluded from the analysis, 507 offices (0.5 percent of offices 

using dental amalgam and exceeding the set-aside revenue threshold) are estimated to incur costs 

exceeding one percent of revenue; no offices are estimated to incur costs exceeding three percent 

of revenue. With baseline set-asides included in the analysis, 965 offices (0.9 percent of offices 

using dental amalgam) are estimated to incur costs exceeding one percent of revenue; 221 offices 

(0.2 percent of offices using dental amalgam) are estimated to incur costs exceeding three 

percent of revenue. 

Table XI(C)(1)(a): Cost-to-Revenue Analysis Impact 

Summary

Excluding Baseline Set-Aside Offices from Analysis

Total Offices by 

Chair Size

Costs > 1% Revenue Costs >3% Revenue

Number of Chairs Number Percent Number Percent

1-2 chairs 12,197 507 4.2% 0 0.0%

3 chairs 25,835 0 0.0% 0 0.0%

4 chairs 27,976 0 0.0% 0 0.0%

5 chairs 15,194 0 0.0% 0 0.0%

6 chairs 12,047 0 0.0% 0 0.0%

7+ chairs 16,611 0 0.0% 0 0.0%

Total 109,859 507 0.5% 0 0.0%

Including Baseline Set-Aside Offices in Analysis

Total Offices by 

Chair Size

Costs > 1% Revenue Costs >3% Revenue

Number of Chairs Number Percent Number Percent

1-2 chairs 12,197 965 7.9% 221 1.8%

3 chairs 25,835 0 0.0% 0 0.0%
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 53 of 103

4 chairs 27,976 0 0.0% 0 0.0%

5 chairs 15,194 0 0.0% 0 0.0%

6 chairs 12,047 0 0.0% 0 0.0%

7+ chairs 16,611 0 0.0% 0 0.0%

Total 109,859 965 0.9% 221 0.2%

Source: EPA analysis

b) Ratio of the Proposed Rule‟s Capital Costs to Total Dental Office Capital Assets

Table XI(C)(1)(b) reports the findings from this analysis, specifically the weighted 

average of the initial spending on the proposed rule‟s capital costs divided by total assets of 

dental office across the revenue range/number-of-chairs analysis combinations. With baseline 

set-asides excluded from the analysis, the resulting initial capital costs to total capital assets 

values are low, with an average value 0.5 percent to 1.0 percent for the no technology in-place 

case and 0% for the technology in-place case. With baseline closures included in the analysis, 

the resulting initial capital costs to total capital assets values are low, with an average value 0.6 

percent to 1.2 percent for the no technology in-place case and 0% for the technology in-place 

case. 

Table XI(C)(1)(b): Initial Spending as Percentage of Pre-Rule Total Dental Office Capital Assets1

Excluding Baseline Set-Aside Establishments from Analysis

Technology in Place No Technology in Place

Number of Chairs 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%

6 chairs 0.0% 0.0% 0.3% 0.2%

7+ chairs 0.0% 0.0% 0.2% 0.2%

Weighted Average 0.0% 0.0% 0.7% 0.4%

Including Baseline Set-Aside Establishments 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%
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 54 of 103

6 chairs 0.0% 0.0% 0.3% 0.2%

7+ chairs 0.0% 0.0% 0.2% 0.2%

Weighted Average 0.0% 0.0% 0.8% 0.5%

1

EPA used the baseline asset value for the minimum (reported as low) and maximum (reported as high) revenue values by 

number-of-chairs category as the denominator for the ratio. Total proposed rule compliance costs, as described in Section X.B 

above, were assigned to each number-of-chairs category as the numerator for the ratio.

c) Ratio of the Proposed Rule‟s Capital Costs to Annual Dental Office Capital Replacement 

Costs Results

EPA compared the estimated total initial spending on the proposed rule‟s capital costs to 

the estimated capital replacement costs across all chair-sizes. The resulting values for the 

proposed option range from 2.9 percent to 3.5 percent, with a weighted average of 2.9 percent 

across all chair size ranges. 

Table XI(C)(1)(c): Initial Spending as Percentage of Estimated Annual Dental Office Capital 

Replacement Costs1

Number of chairs

1-2 chairs 3.4%

3 chairs 3.2%

4 chairs 2.6%

5 chairs 2.2%

6 chairs 2.9%

7 chairs 3.5%

8 chairs 3.1%

9 chairs 2.9%

Weighted Average 2.9%

Source: EPA Analysis

1

EPA estimated capital replacement costs, accounting for the total value of equipment purchases for different 

numbers of chairs, and the composition of purchases by equipment life category by number-of-chairs as the 

denominator for the ratio. Total proposed rule compliance costs, as described in Section X.B above, were assigned to 

each number-of-chairs as the numerator for the ratio.

2. Economic Achievability

The analyses performed above demonstrate the impact of this proposed rule on the dental 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 55 of 103

office sector. In the cost-to-revenue analysis, EPA found that no more than 0.2% of offices, 

mostly in the lower revenue ranges, would potentially incur costs in excess of three percent of 

revenue. The two financial ratios reported in D.1.b and D.1.c show that the proposed option 

would not cause dental offices to encounter difficulty in financing initial spending on capital 

costs of the proposed regulatory option. Based on the results of the three analyses above in 

combination, and EPA‟s inability at this time to conduct a traditional facility closure analysis, 

EPA has determined that the proposed pretreatment standard is economically achievable. EPA 

notes that, due to a lack of data, the economic impact analyses did not include large institutional 

facilities. However, the results of the economic analyses performed on a range of office sizes 

indicate that today‟s proposal is economically achievable at every level. Therefore, EPA projects 

the rule would similarly be achievable for large institutional facilities. EPA requests comment on 

this projection and data to perform economic achievability analyses. 

D) Economic Impact for New Sources

EPA has determined that today‟s proposed pretreatment standard for new sources would 

not impose a barrier to entry. 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 & Child Oral Health Resource Center at Georgetown University (See DCN 

xxx). Information from Georgetown demonstrates that the amalgam separator capital costs 

(based on costs for existing model facilities as described in Section IX) comprised 0.3 percent to 

0.4 percent of the cost of starting a dental practice and therefore, does not pose a barrier to entry.

Table XI(C)(1)(d):: Initial Spending as Percentage of Estimated Dental Office Start-Up 

Costs
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 56 of 103

Number-of-chairs

1-2 chairs 0.4%

3 chairs 0.4%

4 chairs 0.3%

5 chairs 0.3%

6 chairs 0.3%

7 chairs 0.4%

8 chairs 0.4%

9 chairs 0.3%

Weighted Average 0.3%

Source: EPA Analysis

XII. Pollutant Reductions to POTWs and Surface Waters

Consistent with its costing methodology, EPA‟s pollutant reduction methodology 

assumes 2008 ISO 11143 amalgam separators on the market today with Best Management 

Practices, the proposed technology basis, would be used to comply with today‟s proposed rule. 

As was the case for costing, EPA does not have office specific discharge data for the 

approximately 110,000 in-scope dental offices. Instead, EPA has modeled the discharges of 

mercury based on nationwide estimates of amalgam restorations and removals. In other words, 

EPA did not calculate the pollutant reductions on a per office basis. Rather, EPA calculated 

average mercury loadings by dividing the total number of annual procedures by the total number 

of dentists performing the procedure18. This is the same approach and data that EPA presented in 

its Health Services Industry Detailed Study (EPA 821-R-08-014). Further, EPA did not receive 

comments on this part of the Health Study that would cause EPA to reconsider its approach, and 

 

18 Because this approach is based on the number of dentists, it includes those dentists both at offices and institutional 

facilities.
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 57 of 103

therefore EPA has not changed the overall methodology. The following sections describe the 

method in more detail.

A. Nationwide Estimate of Annual Mercury Discharges from Dental Offices

First, EPA estimated the amount of mercury potentially discharged nationwide through 

amalgam restorations. EPA‟s main source of the data underlying all of the estimates related to 

restorations is Vandeven and McGinnis, 2005 [see DCN]. EPA estimates 71 million restorations 

occur at dental offices annually and that these restorations are performed with one amalgam 

capsule per restoration. Each amalgam capsule contains 450 mg of mercury and, on average, 75 

percent of the capsule is used for the filling, with the remaining 25 percent remaining in the 

capsule. Therefore, 340 mg of mercury (75 percent of the capsule) are used per filling. Further, 9 

percent of the 340 mg of mercury, or 31 mg, is discharged to the POTW as carvings and filings 

or other waste. Thus, EPA estimates a total of 2.4 tons of mercury nationwide19 is discharged 

annually to POTWs from restorations. 

Second, EPA modeled mercury discharges from amalgam removals. Similar to 

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 

approximately 97 million amalgam removals occur each year. An average of 300 mg mercury is 

removed from the filling. Ninety percent of the removed filling is assumed to be discharged to 

wastewater, and the other 10 percent is handled as dry waste and/or gray bagged. Thus, EPA 

estimates 29 tons of mercury is discharged to POTWs from removals each year. 

 

19 71 million restorations times 31 mg per restoration. 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 58 of 103

Summing the total mercury discharged from restorations plus that associated with filling 

removals, 31.4 tons of mercury is potentially discharged annually to POTWs from dental offices. 

However, these calculations do not account for the amount of mercury removed at the dental 

office and prior to POTW discharge through existing chair side traps, vacuum pump filters, 

and/or amalgam separators as described below.

B. National Estimate of Annual Baseline Discharges of Mercury from Dental Offices to 

POTWs

As described in Section IV, approximately 40 percent of dental offices operate dental 

amalgam separators. Thus, on a nationwide basis, approximately 65 thousand dental offices 

currently do not have separators and 44 thousand offices already have separators in place. Of 

those that do not currently have separators in place, EPA assumed that 20% do not install or 

remove amalgam. For the remainder, based on information in its record, EPA assumes all 

offices have chair side traps and/or vacuum filters that result in 68 and 78 percent collection of 

dental amalgam, respectively (Vandeven and McGinnis). After accounting for mercury 

reductions achieved through existing chair side traps, vacuum filters, and separators, as 

appropriate, EPA estimates the offices without separators that place or remove amalgam 

collectively discharge a total of 4.4 tons of mercury to POTWs per year. The offices with 

separators collectively discharge approximately 76 pounds of mercury to POTWs per year. 

Thus, EPA calculates the current nationwide annual baseline pounds of mercury discharged to 

POTWs from dental offices to be 4.4 tons mercury (out of a total of the 31.4 tons mercury 

originally generated). See Chapter X of the TEDD for more information.
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 59 of 103

C. National Estimate of Annual Baseline Discharges of Other Metals Contained in 

Amalgam from Dental Offices to POTWs

Amalgam is comprised of roughly 49% mercury, 35% is silver, 9% tin, 6% copper and 

small amounts of zinc. [Massachusetts Water Resources Authority, 2001] As explained earlier in 

Section VIII, EPA concludes the technology basis for today‟s proposal would be equally 

effective in reducing discharges of silver, tin, copper, and zinc as it is in reducing mercury. EPA 

similarly assumes chair side traps and vacuum filters will result in 68 and 78 percent collection 

of these metals, respectively. Accordingly, after accounting for existing technologies at dental 

offices, EPA estimates that in addition to 4.4 tons of mercury, approximately 4.6 tons of these 

additional metals are discharged to POTWs annually for a total metal discharge to POTWs of 9

tons annually. 

D. National Estimate of Annual Pollutant Reductions to POTWs Associated with Today‟s 

Proposal

1. Mercury

EPA estimates the 52 thousand offices that install separators would obtain 98.8 % 

removal by amalgam separator (median removal efficiency of amalgam separators; see 6.1 of 

TEDD). This would result in reduction of total mercury discharges to POTWs by 4.3 tons. 

Because dissolved mercury accounts for much less than 1% of total mercury, [Stone, 2004] and 

because amalgam separators are not effective in removing dissolved mercury, the dissolved 

mercury contribution and associated reduction in loads is assumed to be negligible. EPA solicits 

comment and data on this assumption.

2. Other Metals
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 60 of 103

As explained earlier in Section XIV, EPA concludes the technology basis for today‟s 

proposal would be equally effective in reducing discharges of silver, tin, copper, and zinc as it is 

in reducing mercury. Accordingly, EPA estimates a reduction of these metal discharges to 

POTWs of approximately 4.5 tons. 

3. Total Reductions

EPA estimates today‟s proposal 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.

E. National Estimate of Annual Pollutant Reductions to Surface Waters Associated with 

Today‟s Proposal

In order to evaluate final discharges of mercury (and other metals) to waters of the U.S. 

by the POTW, EPA used its POTW Study to calculate POTW removals of each metal. As 

explained above, at baseline and prior to implementation of this proposal, EPA estimates 4.4 tons

of dental mercury is collectively discharged annually to POTWs. Based on the 50 POTW Study,

EPA estimates POTWs remove 90% of the 4.4 tons mercury from the wastewater. Thus, POTWs 

collectively discharge 880 lbs of mercury from dental amalgam to surface waters annually. 

Under today‟s proposed rule, 98.8 percent of the solid mercury currently discharged annually to 

POTWs will be removed prior to the POTW. The POTWs then further remove 90% of total 

mercury from the wastewater. This reduces the total amount of dental mercury discharged from 

POTWs nationwide to surface water to 17 lbs of mercury annually. In other words, discharges of 

mercury to waters of the U.S. are expected to be reduced by 860 pounds per year20. Similarly, 

EPA‟s POTW study data shows 79 to 88 percent of other metals in the wastewater are removed 

 

20Dissolved mercury accounts for a portion of surface water discharges, because amalgam separators do not remove 

dissolved mercury.
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 61 of 103

by POTWs. As explained above, EPA estimates 4.6 tons of other metals are also collectively 

discharged annually to POTWs. Thus POTWs collectively discharge approximately 1280 lbs of 

other metals to surface waters annually. Following compliance with today‟s proposed rule, the 

total amount of other metal discharges from POTWs nationwide to surface waters will be 

approximately 24 lbs or a reduction of 1256 lbs. See TEDD for more details.

XIII. Cost Effectiveness

EPA also conducted an analysis of the cost-effectiveness of the proposed option. For 

more information about the methodology, data, and results see the cost effectiveness section of 

the TEDD. The results of this cost-effectiveness analysis are expressed in terms of the costs (in 

1981 dollars) per pound-equivalent removed, where pounds-equivalent removed for a particular 

pollutant is determined by multiplying the number of pounds of a pollutant removed by an option 

by a toxic weighting factor (TWF). The toxic weighting factors account for the differences in 

toxicity among pollutants and are derived using chronic aquatic life criteria (or toxic effect levels) 

and human health criteria (or toxic effect levels) established for the consumption of fish. For this 

proposal, EPA used the annual pounds removed for mercury, silver, tin, copper and zinc. The 

TWF for these pollutants is shown in Table XIII(a).

Table XIII(a): Toxic Weighting Factors for Pollutants in Dental 

Amalgam

Total Mercury 

117.12 

Silver 

16.47 

Tin 

0.30 

Copper 

0.63 

Zinc 

0.05 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 62 of 103

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, 

and for this proposal is expressed as the average cost-effectiveness for the option. Average costeffectiveness 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 proposal has a cost-effectiveness ratio 

of $182 - $202/lb-equivalent. This cost-effectiveness ratio falls within industry comparisons of 

PSES cost-effectiveness. A review of approximately 25 of the most recently promulgated or 

revised categorical pretreatment standards demonstrates that PSES cost effectiveness ranges 

from approximately $1/lb-equivalent (Inorganic Chemicals) to $380/lb-equivalent 

(Transportation Equipment Cleaning) in 1981 dollars. 

Table XIII(b): PSES Cost Effectiveness Analysis

Proposed Option

Pre-tax total annualized 

costs ($1981 M)

Removals (lbs-eq) Average cost 

effectiveness

ADA National Survey $23 119,646 $202

Colorado Survey $21 119,646 $182

XIV. Environmental Assessment

A. Environmental Impacts

EPA conducted a literature review concerning potential environmental impacts associated 

with mercury in dental amalgam discharged to surface water by Publically Owned Treatment 

Works (POTWs). [See “Literature Review of the Impacts of Mercury from Dental Amalgam in 

Wastewater,” record document number ___]. Studies indicate that dental offices are the largest 

source of mercury entering POTWs. The total annual baseline discharge of dental mercury to 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 63 of 103

POTWs is approximately 8,800 pounds (4.4 tons): 8,448 pounds are in the form of solid particles 

and 352 pounds (4 percent) are dissolved in the wastewater. Through POTW treatment, 

approximately 90 percent of dental mercury is removed from the wastewater and transferred to 

sewage sludge. The ten percent of dental mercury not removed by POTW treatment is 

discharged to surface water. EPA estimates that POTWs annually discharge approximately 880 

pounds of dental mercury nationwide.

The Clean Water Act regulations known as Standards for Use and Disposal of Sewage

Sludge, 40 C.F.R. part 503, control the land application, surface disposal, and incineration of 

sewage sludge generated by POTWs. Of the 11.2 billion dry pounds of sewage sludge generated 

annually, about 60 percent, or 6.7 billion pounds, are treated to produce biosolids for beneficial 

use as a soil amendment and applied to about 0.1 percent of agricultural lands in the United 

States (National Research Council, 2002). Approximately 4,800 pounds per year of dental 

mercury are contained in land applied biosolids. 

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. Approximately 1,400 pounds per year of dental mercury are contained in surface 

disposed sewage sludge. Pollutant limits and monitoring requirements for surface disposed 

sewage sludge mono-fills are set by 40 C.F.R. part 503 and by 40 C.F.R. part 258 for municipal 

landfills. There may be additional State or local regulations that are more stringent than the 

federal biosolids regulations.

The remaining 22 percent, or 2.5 billion pounds, of sewage sludge generated annually by 

POTWs is disposed of through incineration. An estimated 35 pounds of dental mercury are 

emitted to the atmosphere annually from incineration of sewage sludge (U.S. EPA, 2005); about 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 64 of 103

11.5 pounds of which are deposited within the conterminous United States (U.S. EPA, 1997). 40 

CFR Part 503, Subpart E sets requirements for the incineration of mercury and other toxic metals

in sludge. For mercury, Subpart E provides that incineration of sludge must meet the 

requirements of the National Emissions Standards for Mercury in subpart E of 40 CFR Part 61. 

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 aquatic food chains as larger fish eat 

smaller fish. Fish commonly eaten by humans may have methylmercury levels 100,000 times 

that of ambient water. The neurological effects of consumption of methylmercury contaminated 

fish are well documented. 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 to occur in wild populations of fish, birds, and 

mammals in many areas of the United States. A plausible link has between identified between 

anthropogenic sources of mercury in the United States and methylmercury in fish. However, fish 

methylmercury concentrations also result from existing background concentrations of mercury 

which may consist of mercury from natural sources, mercury re-emitted from the oceans or soils, 

and mercury deposited in the United States from sources in other countries. Given the current 

scientific understanding of the environmental fate and transport of mercury, it is not possible to 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 65 of 103

quantify how much of the methylmercury in fish consumed by the U.S. population is contributed 

by U.S. emissions relative to international mercury sources or natural mercury sources. 

EPA was unable to assess the specific 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. 

B. Environmental Benefits

While EPA did not perform an environmental benefits analysis of today‟s proposed rule,

due to insufficient data about the aquatic fate and transport of dental mercury discharged by 

POTWs, EPA was able to assess the qualitative environmental benefits based on existing 

information. For example, EPA has identified studies that show 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 [See “Literature 

Review of the Impacts of Mercury from Dental Amalgam in Wastewater,” record document 

number ___.] The proposed pretreatment standards will produce human health and ecological 

benefits by reducing the estimated annual nationwide POTW discharge of dental mercury to 

surface water from 878 pounds to 17 pounds.
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 66 of 103

XV. Non-Water Quality Environmental Impacts Associated with the Proposed 

Technology Basis

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 limitations 

guidelines and standards. To comply with these requirements, EPA considered the potential 

impact of the collection and treatment technologies on energy consumption, air pollution, and 

solid waste generation. EPA anticipates that today‟s proposed rule would produce minimal nonwater quality impacts. The Administrator has determined that these very minimal impacts are 

acceptable. For additional information on the analysis of these non-water quality impacts, see the 

Technical and Economic Development Document. 

A. Energy Requirements

Net energy consumption considers the incremental electrical requirements associated 

with operating and maintaining dental amalgam separators, which used in combination with 

BMPs, is the technology basis for the proposed rule standards. As described in Section VII, an 

amalgam separator in a dental office is installed between chairs used for treatment and the 

vacuum pump. Amalgam separators use sedimentation, either alone or in conjunction with 

filtration to remove solids in the waste stream. Most separators rely on gravity or the suction of 

the existing vacuum system to operate, and do not require an additional electrical power source. 

As a result, EPA expects operation of an amalgam separator would pose negligible additional 

energy requirements on the existing vacuum pump.
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 67 of 103

While the vendor data used to support today‟s proposed rule has not identified 

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 

[DCN xxxx, McManus, 2003]. EPA has found that these pumps are designed to operate only at 

the end of the day or overnight, when the vacuum system is turned off. EPA believes 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 of energy requirements associated with today‟s proposed rule, EPA concludes there 

will be no significant non-water quality impacts associated with the energy requirements of 

today‟s rule.

B. Air Emissions

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 [DCN xxx, Stone, 2004]. Because the majority of dental 

mercury is bound to solid particles, it likely will not volatize to the atmosphere. Therefore, EPA 

expects the proposed PSES and PSNS will not pose any increases in air pollution. EPA 

concludes there will be no significant non-water quality impacts associated with air emissions as 

a result of today‟s rule.

C. Solid Waste Generation

As explained above in Section VII, in the absence of amalgam separators, a portion of the 

amalgam rinsed into chair side drains is collected by chair side traps. The remainder is 

discharged to the POTW where the vast majority is removed from the wastewater and becomes 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 68 of 103

part of the POTW sludge that may be land applied, disposed of in landfills or mono-fills, or 

incinerated. Today‟s proposed rule is expected to increase the use of amalgam separators 

nationwide by one and a half times, since EPA estimates 40 percent of dental offices have 

separators installed, with a corresponding increase in collection of used amalgam prior to POTW 

discharge and recycling of amalgam via the spent separator canisters. EPA expects the operation 

and maintenance requirements associated with the amalgam separator compliance option

included as part of the proposed rule will further promote recycling as the primary means of 

amalgam waste management. In summary, EPA expects today‟s rule will not create additional 

solid waste, but will instead result in a shift in 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 concludes there will be a reduction in non-water 

quality impacts associated with solid waste generation as a result of today‟s proposed rule.

XVI. Implementation and Proposed Changes to General Pretreatment Regulations in 

Part 403

A. Implementation Deadline

1. 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 provides categorical pretreatment 

standards “shall specify a time for compliance not to exceed three years from the date of 

promulgation.” See also 40 C.F.R. 403.6(b). In proposing a compliance date for existing 

sources subject to this proposed rule, EPA considered several factors. First, EPA considered the 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 69 of 103

burden on Control Authorities (POTWs) of implementing this rule on an industry consisting of 

approximately 110,000 dental offices, many of whom 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 ten 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 today‟s proposed rule. Moreover, EPA envisions that dental 

offices may use the entire three year period to come into compliance with the numeric standard 

(using amalgam separators) and implement the required BMPs. 

2. New Sources.

For new sources, the compliance deadline is governed by EPA‟s regulation at 40 C.F.R. § 

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.” 

B. Upset and Bypass Provisions

A “bypass” is an intentional diversion of the streams from any portion of a treatment 

facility. An “upset” is an exceptional incident in which there is unintentional and temporary 

noncompliance with technology-based permit effluent limitations because of factors beyond the 

reasonable control of the permittee. EPA's regulations for indirect dischargers concerning 

bypasses and upsets are set forth at 40 C.F.R. §§ 403.16 and 403.17.
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 70 of 103

C. Variances and Modifications

The CWA requires application of pretreatment standards established pursuant to sections 

304 and 307 for all indirect dischargers. However, the statute provides for the modification of 

these national requirements in a limited number of circumstances. Moreover, the Agency has 

established administrative mechanisms to provide an opportunity for relief from the application 

of the national pretreatment standards for categories of existing sources. 

1. Fundamentally Different Factors Variance

EPA may develop pretreatment standards different from the otherwise applicable 

requirements if an individual discharger is fundamentally different with respect to factors 

considered in establishing the standards applicable to the individual discharger. Such a 

modification is known as a "fundamentally different factors" (FDF) variance. See 40 CFR 

403.13. EPA, in its initial implementation of the effluent guidelines and standards program, 

provided for the FDF modifications in regulations. These were variances from the BCT effluent 

limitations, BAT limitations for toxic and nonconventional pollutants and BPT limitations for 

conventional pollutants for direct dischargers. FDF variances for toxic pollutants were 

challenged judicially and ultimately sustained by the Supreme Court. (Chemical Manufacturers 

Association v. Natural Resources Defense Council, 479 U.S. 116 (1985)).

Subsequently, in the Water Quality Act of 1987, Congress added new CWA section 

301(n). This provision explicitly authorizes modifications of the otherwise applicable BAT 

effluent limitations or categorical pretreatment standards for existing sources if a discharger is 

fundamentally different with respect to the factors specified in CWA section 304 or 403(other 

than costs) from those considered by EPA in establishing the effluent limitations or pretreatment

standards. CWA section 301(n) also defined the conditions under which EPA may establish 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 71 of 103

alternative requirements. Under sec. 301(n), an application for approval of a FDF variance must 

be based solely on (1) information submitted during rulemaking raising the factors that are 

fundamentally different or (2) information the applicant did not have an opportunity to submit. 

The alternate limitation or standard must be no less stringent than justified by the difference and 

must not result in markedly more adverse non-water quality environmental impacts than the 

national limitation or standard. 

EPA regulations at 40 C.F.R. part 403, authorizing the Regional Administrators to 

establish alternative standards, further detail the substantive criteria used to evaluate FDF 

variance requests for existing dischargers to POTWs. Thus, 40 C.F.R. § 403.13(d) identifies six 

factors (e.g., volume of process wastewater, age and size of a discharger's facility) that may be 

considered in determining if a discharger is fundamentally different. The Agency must 

determine whether, based on one or more of these factors, the discharger in question is 

fundamentally different from the dischargers and factors considered by EPA in developing the 

nationally applicable pretreatment standards. The regulation also lists four other factors (e.g., 

inability to install equipment within the time allowed or a discharger's ability to pay) that may 

not provide a basis for an FDF variance. In addition, under 40 C.F.R. § 403.13(c)(2), a request 

for standards less stringent than the national standard may be approved only if compliance with 

the pretreatment standards would result in either (a) a removal cost wholly out of proportion to 

the removal cost considered during development of the pretreatment standards, or (b) a nonwater quality environmental impact (including energy requirements) fundamentally more 

adverse than the impact considered during development of the pretreatment standards. The 

legislative history of sec. 301(n) underscores the necessity for the FDF variance applicant to 

establish eligibility for the variance. EPA's regulations at 40 CFR § 403.13 are explicit in 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 72 of 103

imposing this burden upon the applicant. The applicant must show that the factors relating to the 

discharge controlled by the applicant's permit which are claimed to be fundamentally different 

are, in fact, fundamentally different from those factors considered by EPA in establishing the 

applicable pretreatment standards. In practice, very few FDF variances have been granted for 

past ELGs. An FDF variance is not available to a new source subject to PSNS.

2. Economic Variances

Section 301(c) of the CWA authorizes a variance from the otherwise applicable PSES 

and PSNS for nonconventional pollutants due to economic factors. As this rule controls toxic 

pollutants and only controls nonconventional pollutants that are also found in the same 

wastestream, this variance would not be applicable to this particular rule.

D. What Are the Roles of Key Entities Involved in Implementing the Rule and How Are 

Pretreatment Standards Implemented? 

EPA recognizes the role of many interested parties in the development of, and, 

ultimately, the successful implementation of pretreatment standards for dental dischargers. To 

the greatest extent possible, EPA has attempted to strike a reasonable balance among the many 

interests. A short summary of the various roles involved in implementing categorical 

pretreatment standards is provided below.

1. Control Authorities. The “Control Authority” refers to the POTW if the POTW has an 

approved pretreatment program, or the Approval Authority if it has not been approved, which 

may be the State or EPA. A Publicly Owned Treatment Works (POTW) is a treatment works as 

defined by section 212(2) of the Clean Water Act, which is owned by a State or municipality (as 

defined in CWA sections 502 (3) and (4), respectively). (See 40 C.F.R. § 403.3(q).) POTWs 

collect wastewater from homes, commercial buildings, and industrial facilities and typically 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 73 of 103

transport it via a series of pipes, known as a collection system, to the treatment plant. Most 

POTWs are not designed to treat the toxics in commercial and industrial wastes, which can cause 

pass through, interfere with, or are otherwise incompatible with the operation of POTWs, 

including sludge disposal methods at POTWs. The General Pretreatment Regulations require 

POTWs that meet certain criteria (e.g. minimum design flow) to develop Pretreatment programs 

to control industrial Discharges into their sewage collection systems, unless the Pretreatment 

State exercises its option to assume local responsibilities as provided in EPA‟s regulations at 40 

CFR § 403.10(e) and (f). Today there are an estimated 1500 approved POTW Pretreatment 

Programs. As required under Part 403, Control Authorities implement and enforce control 

mechanisms (e.g., permits) to the Industrial Users that discharge to their systems, inspect and 

sample, and enforce control requirements in order to protect the POTW against discharges which 

“pass through” or cause interference” with the POTW (see 40 C.F.R. §§ 403.3(p) and (k).

2. Approval Authority. The Director in an NPDES State with an approved State 

pretreatment program may be authorized to serve as the Approval Authority for the 

implementation of a general pretreatment program. (40 C.F.R. § 403.3(c). Thirty-six states have 

such approved pretreatment programs and are authorized to serve as Approval Authorities for 

implementation of the Pretreatment Program. In a non-NPDES State or an NPDES State without 

an approved State pretreatment program, the EPA Regional Administrator is the Approval 

Authority. 

3. EPA. EPA establishes and implements national regulations for pretreatment programs 

and categorical pretreatment standards for certain industries such as the pretreatment standards 

for dentists proposed today. EPA also develops policy and guidance and provides training and 

oversight for pretreatment program implementation. As noted above, EPA‟s Regional 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 74 of 103

Administrator serves as the Approval Authority for a non-NPDES State or an NPDES State 

without an approved State pretreatment program, and as the Control Authority for POTWs 

without an approved Pretreatment Program in these states.

4. Industrial Dischargers (i.e. dentists). Industrial Users (IUs) of POTWs must comply with 

Pretreatment Standards prior to introducing pollutants into a POTW. The General Pretreatment 

Regulations include general prohibitions that forbid Industrial Users from causing pass through 

and 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), and specific prohibitions 

against the discharge of pollutants that cause problems at the POTW such as corrosion, fire or 

explosion, and danger to worker health and safety. As is being discussed in today‟s notice, EPA 

may also develop national categorical pretreatment standards, including numeric pollutant limits 

and Best Management Practices, for Industrial Users in specific industrial categories. The 

General Pretreatment Regulations include reporting and other requirements necessary to 

implement these categorical Standards (e.g., 40 CFR 403.12).

E. What are the control authority requirements under existing general pretreatment 

regulations?

The current regulations require certain minimum oversight of Industrial Users by Control 

Authorities, which are typically POTWs with Approved Pretreatment Programs but could be 

States or EPA acting as Pretreatment Control Authorities. The required minimum oversight 

includes receipt and analysis of reports and other notices submitted by IUs, randomly sampling

and analyzing effluent from IUs, and conducting surveillance activities to identify occasional and 

continuing non-compliance with pretreatment standards. In addition, for IUs designated as 

significant (SIU), per 40 CFR § 403.3(v), Control Authorities must inspect and sample the SIU 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 75 of 103

effluent annually, review the need for a slug control plan, and issue a Permit or equivalent 

control mechanism with a duration not to exceed five years (40 CFR §§ 403.8(f)(1)(iii) and 

403.8(f)(2)(v), 403.10(e) and 403.10(f)(2)(i)). Control authorities may determine that an 

industrial user is a non-significant categorical industrial user or a that an industrial user is not an 

SIU (See 403.3(v)(2) and (3).)

Facilities that are subject to categorical pretreatment standards contained in regulations in 

40 CFR Chapter I, Subchapter N are referred to as Categorical Industrial Users (CIUs). The 

regulations related to Significant Industrial User (SIU) at 40 CFR 403.3(v) define SIU to include 

CIUs, but also provide that a Control Authority may determine that a CIU may be a NonSignificant Categorical Users (NSCIU) if certain conditions are met. (See 403.3(v)(1) and (2). 

State Approval Authorities and POTW Control Authorities who have the legal authority to 

implement the NSCIU classification may find some of their CIUs satisfy the qualifying 

conditions of NSCIU at 40 CFR 403.3(v)(2). Upon such finding, the Control Authority may 

exclude facilities meeting the NSCIU criteria from the SIU definition and its minimum oversight 

requirements. A Control Authority may not exclude CIUs from the requirements of the 

categorical pretreatment standards. 

F. Why Is EPA Revising the Existing General Pretreatment Regulations?

Today, EPA is proposing to amend selected parts of the General Pretreatment 

Regulations in order to simplify oversight requirements for the approximately 110,000 dental 

offices subject to this rule. As mentioned in paragraph E. of this section, when EPA promulgates 

categorical industrial pretreatment standards, as defined in 40 CFR Part 403, affected dischargers 

are referred to as Categorical Industrial Users (CIUs). The number of dental offices subject to 

this rule is approximately ten times the current number of Categorical Industrial Users (CIUs). 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 76 of 103

EPA recognizes 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 the

local, state and federal resources whereas EPA does not expect such efforts to result in greater 

environmental benefit. EPA is focused 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, while at the same time achieving the projected 

pollutant reductions. EPA estimates that these changes to the Existing General Pretreatment 

Standards would reduce costs to POTWs to implement and enforce this proposed rule by $47 

million annually (see TEDD).

G. What Changes Is EPA Proposing to the General Pretreatment Standards?

EPA is proposing a new classification of CIU specifically tailored to the Dental Office 

Effluent Limitations 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 (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 office facilities that fail to meet the compliance requirements of the DIU.

H. When is a Dental Office a DIU?

Under the proposed rule, a dental discharger is given the option of complying with 

monitoring and reporting requirements in 40 CFR § 441.60, which are tailored for dental 

dischargers, in lieu of the otherwise applicable monitoring and reporting requirements in 40 CFR 

part 403. If a dental discharger complies with (1) the special monitoring and reporting 

requirements in 40 CFR § 441.60, (2) the remaining Part 403 requirements, and the applicable 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 77 of 103

pretreatment standards (PSES or PSNS), then the Control Authority may treat the dental 

discharger as a dental industrial user (DIU). The DIU must maintain compliance in order to 

retain its DIU status.

I. When is a dental office not a DIU?

If the dental office does not meet the requirements to be treated as a DIU, under today‟s 

proposal the Control Authority must treat the dental discharger as a Significant Industrial User as 

defined in 40 CFR § 403.3(v). As a Significant Industrial User, the POTW Control Authority 

would be required to conduct the oversight duties applicable to SIUs as described in 40 CFR 

403.8(f). 

J. What oversight responsibilities for DIUs is EPA proposing for Control Authorities?

Today‟s proposal 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 documenting continued eligibility for DIU status. In accordance with 40 C.F.R. 

403.8(f)(2)(viii)(F), a dental discharger 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 elects to 

inspect the facility and finds the facility is not in compliance with 40 CFR§ 441.60. Upon 

discovery that a dental office is not in compliance with regulations at 40 CFR § 441.60 (either 

reporting requirements, 403, or 441 PSES/PSNS requirements), the Control Authority must 

initiate enforcement in accordance with its approved pretreatment program to return the dental 

discharger into compliance. In order for the Control Authority to continue to treat the dentist as a 

DIU, the Control Authority would need to verify and find, through an inspection, that the dental 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 78 of 103

discharger has returned to full compliance with the criteria in 441.60. If, within 90 days, the 

Control Authority inspects, verifies, and finds that the dental discharger has returned to full 

compliance with 441.60, then the dental discharger would remain a DIU. The 90 day compliance 

deadline is consistent with other portions of 40 CFR Part 403 (e.g., significant noncompliance 

compliance report deadlines, 90 day report after effective dates of categorical standards), and 

provides both the dental discharger and Control Authority with an incentive to provide a timely 

return to compliance. If the dental discharger has not returned to compliance within 90 days of 

the initial noncompliance, the Control Authority could no longer treat the dental discharger as a 

DIU and the dental discharger would become a Significant Industrial User. Control Authorities 

are required to provide oversight of SIUs which includes inspection and sampling of 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)). 

K. Can a dental office DIU be a Non-Significant Industrial User (NSCIU)?

EPA is not proposing to prohibit a Control Authority from finding that a dental office 

may qualify as an NSCIU on an individual basis. State Approval Authorities and POTW Control 

Authorities who have the legal authority to implement the NSCIU classification may find that 

one or more of their Dental Office CIUs may qualify as NSCIUs. 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 

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. 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 79 of 103

L. Can Dental Industrial Users be covered under a General Permit?

Although this proposed rule does not require a Control Authority to regulate DIUs as 

SIUs thereby requiring the Control Authority to issue a control mechanism, designation of a 

dental office subject to 40 CFR part 441 as a Dental Industrial User does not preclude a Control 

Authority‟s option to regulate the dental office under a general control mechanism, 40 CFR 

§403.8(f)(1)(iii)(A), if that legal authority is adopted. The General Pretreatment Regulations 

describe conditions which must be met in order for the Control Authority to use a general control 

mechanism in lieu of an individual permit or control mechanism. Provided that the Control 

Authority has adopted the necessary legal authority and has modified its pretreatment program 

to incorporate such authority and procedures, the Control Authority may use a general control 

mechanism or “general permit” for facilities that meet certain minimum criteria for being 

considered substantially similar. The use of general control mechanisms allows the permitting 

authority to allocate resources in a more efficient manner and to provide timelier permit 

coverage, particularly in the circumstances of covering large numbers of similar facilities under a 

single mechanism. EPA considers that most dental offices generally will conform to these 

requirements and could appropriately be covered by a general control mechanism issued by a 

Control Authority. The use of a general control mechanism also ensures consistency of permit 

conditions for similar facilities. Additional information on the use of general control 

mechanisms may be found at 70 FR 60143, October 14, 2005.

M. Would any POTW with a dentist office in its service area be required to develop a 

pretreatment program?

In accordance with 40 CFR 403.8(a), POTWs (or combination of POTWs operated by the 

same authority) with a total design flow greater than 5 million gallons per day and receiving 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 80 of 103

pollutants from Industrial Users which Pass Through or Interfere with the operation of the 

POTW or are otherwise subject to Pretreatment Standards are required to establish a POTW 

Pretreatment Program unless the State with an approved Pretreatment Program exercises its 

option to assume local responsibilities as provided for in 40 C.F.R. 403.10(e) . For smaller 

POTWs, i.e., POTWs that have a design flow of 5 MGD or less, the Regional Administrator or 

State Director may require the POTW to develop a local pretreatment program if the nature or 

volume of the industrial influent, treatment process upsets, violations of POTW effluent 

limitations, contamination of municipal sludge, or other circumstances warrant such 

development in order to prevent Interference or Pass Through. Interference and Pass Through 

are defined at 40 CFR §§ 403.3(k) and (p), respectively. As noted above, a State with an 

Approved State Pretreatment Program may instead assume local responsibilities as provided in 

40 CFR § 403.10(e). EPA anticipates that the approved States will choose to carry out the 

oversight activities themselves rather than requiring a POTW to develop a full pretreatment 

program solely to regulate its dental dischargers. 

N. Would States or municipalities that already implement dental amalgam control programs 

need to modify their regulations?

Today‟s proposed rulemaking would not affect state and local requirements. However, 

states with Approved State Programs and POTWs with approved pretreatment programs would

need to enforce the federal requirements at a minimum. Where ongoing State or POTW Control 

Authority programs require additional information or implementation requirements, the Control 

Authority must implement and enforce both program requirements and, for overlapping 

requirements, the more stringent of the two programmatic requirements.

O. Will States or municipalities that already implement dental amalgam control programs 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 81 of 103

need to issue control mechanisms or permits to impose requirements that are more 

stringent than the federal requirements?

The legal authority requirements for a POTW Pretreatment program only require 

issuance of an individual or general control mechanism to Significant Industrial Users, 40 CFR 

403.8(f)(2)(1)(iii)(A). The proposed regulation modification in the General Pretreatment 

Regulations is to establish a new DIU classification of Industrial User. The proposal indicates 

that a DIU will not be a Significant Industrial User. Where the State or POTW existing dental 

amalgam control programs are equal to or less stringent than today‟s proposal, and the State or 

Control Authority adopt and have their pretreatment programs appropriately approved to 

incorporate EPA‟s DIU provisions, dental offices compliant with the DIU classification will not 

need to be issued a control mechanism.

P. What reports would dental dischargers be required to submit? 

Existing and new dental dischargers could comply with the special reporting 

requirements in Part 441 in lieu of the otherwise applicable reporting requirements in Part 403 by 

submitting the Baseline Report (40 CFR 441.60(a)(1) and the 90 Day Compliance Report (40 

CFR 441.60(a)(2) and Periodic Monitoring reports (40 CFR 441.60(a)(3). Submission of these 

reports would satisfy the reporting requirements in parts 403 and 441. Dental dischargers who 

do not submit reports consistent with the requirements in Section 441.60 would be required to 

submit the reports described in 40 CFR 403.12(b)(d) and (e).

Q. Can the DIU designate a contractor or contract vendor to submit compliance reports to 

the Control Authority or EPA? 

In accordance with 40 CFR 403.12(l), Baseline Monitoring Reports, 90-day Compliance 

Reports, and Periodic monitoring reports (40 CFR 403.12(b), (d), and (e), respectively) must be 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 82 of 103

signed by (1) a responsible corporate officer of the Industrial user if it is a corporation; (2) a 

general partner or proprietor if the Industrial User is a partnership or sole proprietorship; or (3) a 

duly authorized representative of the responsible corporate officer, general partner, or proprietor

if the authorization specifies either an individual or a position having responsibility for the 

overall operation of the facility from which the Industrial Discharge originates, such as the 

position of plant manager or a position of equivalent responsibility for environmental matters for 

the company and the written authorization is submitted to the Control Authority.

R. Would Control Authorities need to modify their SUO and State regulations, respectively, 

to incorporate these changes to 403? 

EPA notes that the today‟s proposed changes to 403 to create the DIU classification are 

changes that the Control Authority may adopt at its discretion. The changes to 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 POTW Pretreatment program would need to incorporate these changes into their legal 

authority under 403.8(f)(l).

XVII. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and Executive Order 13563: 

Improving Regulation and Regulatory Review

Under Executive Order 12866 (58 FR 51735, October 4, 1993), this action is a 

"significant regulatory action.” Accordingly, EPA submitted this action to the Office of 

Management and Budget (OMB) for review under Executive Orders 12866 and 13563 (76 FR 

3821, January 21, 2011) and any changes made in response to OMB recommendations have been 

documented in the docket for this action.
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 83 of 103

B. Paperwork Reduction Act 

The information collection requirements in this proposed rule have been submitted for 

approval to the Office of Management and Budget (OMB) under the Paperwork Reduction Act, 

44 U.S.C. 3501 et seq. The Information Collection Request (ICR) document prepared by EPA 

has been assigned EPA ICR number [XXXX.XX]. To reduce the overall costs associated with 

this rule, in lieu of discharge monitoring, proposed §441.60 allows dentists to certify compliance 

with requirements for amalgam capture and certain best management practices. 

For purposes of this estimate, EPA assumed all affected dentists would elect to comply 

with today‟s proposal through certification rather than discharge monitoring. EPA estimates it 

would take an annual average of 170,000 hours and $2.9 million for affected dental offices to 

collect and report the information required for certification in the proposed rule. This estimate 

includes effort associated with completing the baseline monitoring report, a one-time compliance 

report and an annual compliance certification for each year of this three year ICR. This estimate 

is based on average labor rates from the Bureau of Labor Statistics for the dental office personnel 

involved in collecting and reporting the information required. EPA estimates it would take an 

average of 14,000 hours and $650,000 for permit authorities to review the information submitted 

by dentists that certify they meet the requirements in the proposed rule. EPA estimates that there 

would be no start-up or capital costs associated with the information described above. Burden is 

defined at 5 CFR 1320(b).

An agency may not conduct or sponsor, and a person is not required to respond to, a 

collection of information unless it displays a currently valid OMB control number. The OMB 

control numbers for EPA's regulations in 40 CFR are listed in 40 CFR part 9. 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 84 of 103

To comment on the Agency's need for this information, the accuracy of the provided 

burden estimates, and any suggested methods for minimizing respondent burden, EPA has 

established a public docket for this rule, which includes this ICR, under Docket ID number [XX20XX-XXXX]. Submit any comments related to the ICR to EPA and OMB. See 

ADDRESSES section at the beginning of this notice for where to submit comments to EPA. 

Send comments to OMB at the Office of Information and Regulatory Affairs, Office of 

Management and Budget, 725 17th Street, NW, Washington, DC 20503, Attention: Desk Office 

for EPA. Since OMB is required to make a decision concerning the ICR between 30 and 60 days 

after [Insert date of publication in the Federal Register.], a comment to OMB is best assured 

of having its full effect if OMB receives it by [Insert date 30 days after publication in the 

Federal Register.]. The final rule will respond to any OMB or public comments on the 

information collection requirements contained in this proposal.

C. Regulatory Flexibility Act

The Regulatory Flexibility Act (RFA) generally requires an agency to prepare a 

regulatory flexibility analysis of any rule subject to notice and comment rulemaking 

requirements under the Administrative Procedure Act or any other statute unless the agency 

certifies that the rule will not have a significant economic impact on a substantial number of 

small entities. Small entities include small businesses, small organizations, and small 

governmental jurisdictions.

For purposes of assessing the impacts of today's rule on small entities, small entity is 

defined as: (1) a small business in the Dental Office sector (NAICS 621210) with annual receipts 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 85 of 103

of 7 million dollars or less (based on Small Business Administration size standards) (2) a small 

governmental jurisdiction that is a government of a city, county, town, school district or special 

district with a population of less than 50,000; and (3) a small organization that is any not-forprofit enterprise which is independently owned and operated and is not dominant in its field.

EPA estimates that 109,600 dental offices out of 109,859 dental offices potentially 

subject to today‟s proposal meet the small business definition. EPA‟s analysis of projected 

impacts on small dental offices is described in detail in Section X. EPA projects less than one 

percent of 109,859 affected dental offices would incur compliance costs exceeding one percent 

of revenue and no more than 0.2% would incur compliance costs exceeding three percent of 

revenue. After considering the economic impact of today‟s proposed rule on small entities, I 

certify that this action will not have a significant economic impact on a substantial number of 

small entities. 

Although this proposed rule will not have a significant economic impact on a substantial 

number of small entities, EPA nonetheless has tried to reduce the impact of this rule on small 

entities. First, while some amalgam separators currently used at some dentists are certified to 

meet slightly less mercury removal than required in today‟s proposed rule (e.g., they are certified 

to remove 95% total mercury), today‟s proposal would allow dentists with existing separators to 

satisfy the requirements for a period of up to ten years. See Section VIX. In addition, today‟s 

proposed rule includes a compliance option that would allow dental offices subject to the rule to 

certify proper operation of a widely available, inexpensive technology that meets certain 

requirements in combination with best management practices in lieu of conducting more onerous 

discharge monitoring requirements that would otherwise be associated with pretreatment 

standards. Finally, EPA has tried to minimize impacts to small governments responsible for 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 86 of 103

pretreatment programs by proposing to amend the General Pretreatment Regulations to create the 

DIU classification. The DIU classification reduces oversight responsibilities for Control 

Authorities from the current regulatory scheme, while at the same time achieving the projected 

pollutant reductions. We continue to be interested in the potential impacts of the proposed rule 

on small entities and welcome comments on issues related to such impacts.

D. Unfunded Mandates Reform Act

This proposed rule does not contain a Federal mandate that may result in expenditures of 

$100 million or more for State, local, and tribal governments, in the aggregate, or the private sector 

in any one year. As explained in Section X, the annual cost of the rule is $44 - $49 million. Thus, 

this rule is not subject to the requirements of sections 202 or 205 of UMRA.

The proposal is also not subject to the requirements of section 203 of UMRA, because it 

contains no regulatory requirements that may significantly or uniquely affect small governments. 

EPA has not identified any dental offices that are owned by small governments. While today‟s 

proposal would impact government entities required to administer the proposed pretreatment 

standards, EPA does not expect that this would include any small governments. By statute, a

small government jurisdiction is defined as a government of a city, county, town, school district 

or special district with a population of less than 50,000 (5 U.S.C 601). As explained in Section 

XV, control authorities are responsible for oversight and administration associated with today‟s 

proposal. To qualify as a control authority, a POTW must have a flow of at least 5MGD. The 

average water use per person is 100 gallons per day so a POTW with a population less than 

50,000 would likely have a flow less than 5 MGD. Therefore, EPA does not expect small 

government owned POTWs would meet the definition of a control authority. 

E. Executive Order 13132: Federalism
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 87 of 103

This proposed rule would not have federalism implications. It would not have substantial 

direct effects on the States, on the relationship between the national government and the States, 

or on the distribution of power and responsibilities among the various levels of government, as 

specified in Executive Order 13132. The proposed rule would not alter the basic state-federal 

scheme established in the Clean Water Act under which EPA authorizes states to carry out the 

NPDES permit program. EPA expects the proposed rule would have little effect on the 

relationship between, or the distribution of power and responsibilities among, the federal and 

state governments. Thus, Executive Order 13132 does not apply to this proposed rule.

EPA coordinated closely with states, via ECOS and local governments and with 

NACWA, throughout the development of today‟s proposed rule. In the spirit of Executive Order 

13132, and consistent with EPA policy to promote communications between EPA and State and 

local governments, EPA specifically solicits comment on this proposed rule from State and local 

officials.

F. Executive Order 13175: Consultation and Coordination with Indian Tribal Governments

This proposed rule does not have tribal implications, as specified in Executive Order 

13175 (65 FR 67249, November 6, 2000). It would not have substantial direct effects on Tribal 

governments, on the relationship between the Federal government and Indian Tribes, or on the 

distribution of power and responsibilities between the Federal government and Indian Tribes. 

Today's proposed rule contains no Federal mandates for Tribal governments and does not impose 

any enforceable duties on Tribal governments. Thus, Executive Order 13175 does not apply to 

this rule. EPA specifically solicits additional comment on this proposed action from Tribal 

officials.
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 88 of 103

G. Executive Order 13045: Protection of Children from Environmental Health and Safety Risks

EO 13045 (62 FR 19885, April 23, 1997) applies to rules that are economically 

significant according to EO 12866 and involve a health or safety risk that may disproportionately 

affect children. This action is not subject to EO 13045 because it is estimated to cost less than 

$100 million and does not involve a safety or health risk that may have disproportionately 

negative effects on children. The proposed rule will reduce the amount of mercury from dental 

amalgam entering POTW‟s and eventually the nation‟s waters, which will reduce impacts to the 

neurological development of children.

H. Executive Order 13211: Energy Effects

This proposed rule is not a "significant energy action" as defined in Executive Order 

13211, "Actions Concerning Regulations That Significantly Affect Energy Supply, Distribution, 

or Use" (66 FR 28355, May 22, 2001) because it is not likely to have a significant adverse effect 

on the supply, distribution, or use of energy, as described in Section XIV of today‟s proposal.

EPA determined that any additional energy usage would be insignificant to the total energy 

usage of Dental Offices and total annual U.S energy consumption.

I. National Technology Transfer Advancement Act

Section 12(d) of the National Technology Transfer and Advancement Act (NTTAA) of 

1995, (Public Law 104-113; 15 U.S.C. 272 note) directs EPA to use voluntary consensus 

standards in its regulatory activities unless to do so would be inconsistent with applicable law or 

otherwise impractical. Voluntary consensus standards are technical standards (e.g., materials 

specifications, test methods, sampling procedures, and business practices) that are developed or 

adopted by voluntary consensus standard bodies. The NTTAA directs EPA to provide Congress, 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 89 of 103

through OMB, explanations when the Agency decides not to use available and applicable 

voluntary consensus standards. 

This proposed rulemaking involves technical standards. The International Organization 

for Standardization (ISO) developed efficiency standards for amalgam separators (ISO 11143) in 

1999 and updated these standards in 2008. EPA proposes to use ISO 11143 2008. This voluntary 

standard setting organization established a standard for measuring amalgam separator efficiency 

by evaluating the retention of amalgam mercury using specified test procedures in a laboratory 

setting. It also includes requirements for instructions for use and operation and maintenance.

EPA welcomes comments on this aspect of the proposed rulemaking and, specifically, 

invites the public to identify potentially-applicable voluntary consensus standards and to explain 

why such standards should be used in this regulation.

J. Executive Order 12898: Federal Actions to Address Environmental Justice in Minority 

Populations and Low-Income Populations

Executive Order 12898 (59 FR 7629, Feb. 16, 1994) establishes federal executive policy 

on environmental justice. Its main provision directs federal agencies, to the greatest extent 

practicable and permitted by law, to make environmental justice part of their mission by 

identifying and addressing, as appropriate, disproportionately high and adverse human health or 

environmental effects of their programs, policies, and activities on minority populations and lowincome populations in the United States. 

EPA has determined that this proposed rule will not have disproportionately high and 

adverse human health or environmental effects on minority or low-income populations. While 

EPA was unable to perform a detailed environmental justice analysis because it lacks data on the 

location of POTWs to which dental discharges currently occur, the proposal would increase the 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 90 of 103

level of environmental protection for all affected populations without having any 

disproportionately high and adverse human health or environmental effects on any population, 

including any minority or low-income population. The proposed rule will reduce the amount of 

mercury from dental amalgam entering POTW‟s and eventually the nation‟s waters, to benefit all 

of society, including minority communities.

EPA welcomes comments on this aspect of the proposed rulemaking and, specifically, 

invites the public to identify potential environmental justice considerations associated with this 

proposed regulation.

XII. Solicitation of Data and Comments

A. General and Specific Comment Solicitation

EPA solicits comments on the proposed rule, including EPA‟s rationale as described in 

this preamble. EPA seeks comments on issues specifically identified in the preamble as well as 

any other issues that are not specifically addressed in today's notice. Comments are most helpful 

when accompanied by specific examples or supporting data. Specifically, EPA solicits 

information and data on the following topics.

1. Data demonstrating the effectiveness of polishing, or the use of sorbent columns after 

solids separation, in reducing mercury discharges from dental offices.

2. Data on costs, performance, affordability and availability of polishing in combination 

with amalgam separators.

3. Ways to demonstrate compliance with today‟s proposed rule, its approach for addressing 

offices where no dental amalgam is applied or removed, and its approach for offices that 

already employ a separator.
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 91 of 103

4. Information on the frequency of emergency removals at dental offices that do not place or 

remove amalgam.

5. Other technologies that have demonstrated an ability to reduce discharges of mercury 

from dental offices.

6. Data regarding EPA‟s analysis of clinics and very large facilities.

7. EPA‟s proposed revisions to 40 CFR 403, including revisions to create the DIU category, 

and the means of evaluating ongoing compliance for the purposes of maintaining the DIU 

designation.

8. Information about mobile facilities used to treat patients. EPA seeks information on the 

number, size, operation and financial characteristics of mobile facilities that offer dental 

treatment.

9. EPA‟s estimate of the number of large institutional practices, and the characteristics 

(chair size, number of practitioners, cost of mitigating technology) of these facilities.

10. Additional information on equipment needs and costs for starting a dental practice 

including information on the life of the dental equipment. 

11. Additional information on low revenue dental offices and if they could represent baseline 

closures (See discussion in Section XX of economic analysis). 

12. Additional information on the location and characteristics of low revenue dental offices ( 

(1) single-dentist and/or part-time businesses that provide services as a subcontractor on 

an independent fee-for-service basis (2) non-profit groups, or (3) non-viable as for-profit 

businesses.)
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 92 of 103

List of subjects in 40 CFR Part 441

Environmental protection, Dental Office, Dentist, Dental, Mercury, Waste treatment and 

disposal, Water pollution control, Pretreatment

Dated: 

____________________________

Gina McCarthy,

Administrator.
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 93 of 103

40 CFR Part 403 is amended as follows:

PART 403—GENERAL PRETREATMENT REGULATIONS FOR EXISTING AND 

NEW SOURCES OF POLLUTION

Sec.403.3

Authority: 33 U.S.C. 1251 1251, 1311, 1314, 1316, 1317, 1318, 1342, and 1361.

Add new paragraph(s) to § 403.3 to read as follows:

403.3(v)(4) An industrial user subject to categorical Pretreatment Standards under 40 CFR part 

441 is designated a Dental Industrial User rather than a Significant Industrial User if the 

Industrial User has complied with 40 CFR part 403, the applicable PSES or PSNS and the 

monitoring and reporting requirements of 40 CFR § 441.60. If a Dental Industrial User has not 

complied with these requirements and standards, such Industrial User will be considered a 

Significant Industrial User until the Control Authority evaluates the Industrial User as specified 

in section 403.8(f)(2)(v)(D) of this part. 

Sec.403.8

403.8(f)(2)(v)(D) Where the POTW finds that an Industrial User meets the criteria for 

classification as a Dental Industrial User (DIU), the POTW must evaluate, at least once per year, 

whether the Industrial User meets the criteria in section 403.3(v)(4). In the event that the POTW 

determines that a Dental Industrial User does not meet the criteria in section 403.3(v)(4), the 

POTW must immediately begin enforcement in accordance with its enforcement response plan. 

If the dental discharger has not returned to compliance within 90 days of the initial 

noncompliance, the POTW may no longer treat the dental discharger as a DIU and must treat the 

dental discharger as a Significant Industrial User. Upon verification by the POTW through an 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 94 of 103

inspection and a finding that the dental discharger has complied with all of the applicable 

requirements in 403.3(v)(4), the dental discharger may be considered a DIU.

40 CFR Part 441 is added as follows:

PART 441 – DENTAL OFFICE (MERCURY AMALGAM) POINT SOURCE 

CATEGORY

Sec.

441.10 Applicability.

441.20 General definitions.

441.30 General pretreatment standards

441.40 Pretreatment standards for existing sources (PSES)

441.50 Pretreatment standards for new sources (PSNS)

441.60 Discharge Monitoring, Reporting, and Recordkeeping requirements

Authority: 33 U.S.C. §§ 1251, 1311, 1314, 1316, 1317, 1318, 1342, and 1361. 42 U.S.C §§ 

13101 et seq.

441.10 Applicability.

(a) Except as provided in subparagraph (b) and (c), the provisions of this part are applicable to 

discharges of wastewater to publicly owned treatment works from facilities where the 

practice of dentistry is performed (“dental dischargers”), including but not limited to 

institutions, permanent or temporary offices, clinics, mobile units, home offices, and 

facilities, and including dental facilities owned and operated by Federal, State or local 

governments. 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 95 of 103

(b) The provisions of this part do not apply to process wastewater discharges from dental 

dischargers which exclusively practice one or more of the following dental specialties: oral 

pathology, oral and maxillofacial radiology, oral and maxillofacial surgery, orthodontics, 

periodontics, or prosthodontics;

(c) Dental Dischargers will be exempt from any further requirements of this rule so long as they 

(1) Do not place or remove amalgam 

(2) Certify to the control authority that that they do not and will not use or remove 

amalgam, including the following information: 

i. the facility name, address, contact information

ii. the dental license number of all practicing dentists at the location

(3) notify the control authority of any changes to information required under 2(i) and 

2(ii)

(4) Information provided to comply with 2(i) and 2(ii) must be signed by the 

responsible corporate officer as defined in 403 (12)(l)

441.20 General definitions.

For purposes of this part:

Amalgam separator means a collection device designed to capture and remove dental amalgam 

from the amalgam process wastewater of a dental facility.

Control Authority is defined in 40 CFR § 403.3(f).

Dental amalgam means an alloy of elemental mercury and other metals that is used in the 

practice of dentistry. 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 96 of 103

Dental Industrial User (DIU) means a dental discharger as described in 441.10(a) that meets the 

requirements of 40 CFR §441.60.

Dental Discharger means a source of wastewater to a publicly owned treatment works from a facility 

where the practice of dentistry is performed as described in 40 CFR § 441.10.

Amalgam process wastewater means any wastewater generated and discharged by a dental 

discharger through the practice of dentistry that may contain dental amalgam.

441.30 General Pretreatment Requirements

Any source subject to this part that introduces process wastewater pollutants into a publicly 

owned treatment works (POTW) must comply with 40 CFR Part 403.

441.40 Pretreatment standards for existing sources (PSES)

Except as provided in 40 CFR 403.7 (removal credits) and 403.13 (fundamentally different 

factors) and no later than [3 years after effective date], any existing source subject to this part 

must achieve the following pretreatment standards:

(a) Removal of at least 98.8% of total mercury from amalgam process wastewater and 

(b) Incorporation of the following best management practices: 

(i) Scrap amalgam (contact and non-contact), including but not limited to 

dental amalgam from chair-side traps, screens, vacuum pump filters, 

dental tools, or collection devices may not be flushed down the drain.

(ii) Chair-side traps that may drain to a sewer must be cleaned with nonbleach, non-chlorine containing cleaners that have a pH of 6 to 8. Such 

cleaning must be conducted at least weekly. 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 97 of 103

(iii) Certification that the best management practices specified in (i) and (ii) of 

this subpart are being followed is deemed to meet these requirements.

(c) The requirements of subsection (a) may be met by installation and operation of at 

least one 2008 ISO 11143 certified amalgam separator that:

(i) is certified to meet a removal efficiency of no less than 98.8%;

(ii) receives all amalgam process wastewater;

(iii) is sized to incorporate all wastewater that may pass through it; 

(iv) is inspected at least once per month to ensure proper operation and 

maintenance of the separator, including confirmation that amalgam 

process wastewater is flowing through the retaining cartridge, separator 

canister, or amalgam separating portion of the amalgam separator 

(preventing bypass); 

(v) in the event that the separator is found to not be functioning properly, is 

repaired or replaced according to manufacturer instructions; and 

(vi) is regularly maintained by replacing the amalgam retaining cartridge(s), 

separator canister(s), or separator unit(s) whenever the collection of 

retained solids reaches the manufacturer‟s stated design capacity or 

annually, whichever comes first. 

(d) Dental Dischargers that operate an amalgam separator certified under the 1999 or 

2008 ISO 11143 standard installed at a dental facility prior to [insert date of 

proposed rule], satisfy the requirements of subsection (a) until [insert date that is 10 

years from the effective date of the rule] if the existing amalgam separator: 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 98 of 103

(i) receives all amalgam process wastewater;

(ii) is sized to incorporate all amalgam process wastewater that may pass 

through it; 

(iii) is inspected at least once per month to ensure proper operation and 

maintenance of the separator, including confirmation that wastewater is 

flowing through the retaining cartridge, separator canister, or amalgam 

separating portion of the amalgam separator (preventing bypass); and 

(iv) is regularly maintained by replacing the amalgam retaining cartridge(s), 

separator canister(s), or separator unit(s) whenever the collection of 

retained solids reaches the manufacturer‟s rated design capacity or 

annually, whichever comes first.

441.50 Pretreatment Standards for New Sources (PSNS)

Except as provided in 40 CFR 403.7 (removal credits) and 403.13 (fundamentally different 

factors), any new source subject to this part must achieve PSNS as follows: 

(a) Removal of at least 98.8% of total mercury from amalgam process wastewater and 

(b) Incorporation of the following best management practices: 

i. Scrap amalgam (contact and non-contact), including but not limited to 

dental amalgam from chair-side traps, screens, vacuum pump filters, 

dental tools, or collection devices may not be flushed down the drain.

ii. Chair-side traps that may drain to a sewer must be cleaned with nonbleach, non-chlorine containing cleaners that have a pH of 6 to 8. Such 

cleaning must be conducted at least weekly. 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 99 of 103

iii. Certification that the best management practices specified in (i) and (ii) of 

this subpart are being followed is deemed to meet these requirements.

(c) The requirements of subsection (a) may be met by installation and operation of at 

least one 2008 ISO 11143 certified amalgam separator that: 

(i) is certified to meet a removal efficiency of no less than 98.8%;

(ii) captures all amalgam process wastewater;

(iii) is sized to incorporate all amalgam process wastewater that may pass 

through it; 

(iv) is inspected at least once per month to ensure proper operation and 

maintenance of the separator, including confirmation that amalgam 

process wastewater is flowing through the retaining cartridge, separator 

canister, or amalgam separating portion of the amalgam separator 

(preventing bypass); 

(v) in the event that the separator is found to not be functioning properly, is 

repaired or replaced according to manufacturer instructions; and 

(vi) is regularly maintained by replacing the amalgam retaining cartridge(s), 

separator canister(s), or separator unit(s) whenever the collection of 

retained solids reaches the manufacturer‟s stated design capacity or 

annually, whichever comes first. 

441.60 Discharge Monitoring, Reporting, and Recordkeeping requirements.

(a) Dental dischargers may comply with the following monitoring and reporting 

requirements in lieu of the otherwise applicable requirements in 403.12(b), (d) and (e). 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 100 of 103

(1) Baseline Report. For existing sources, a Baseline Report must be submitted 

within 180 days of the effective date of this rule. For new sources, a Baseline 

Report must be submitted at least 90 days prior to commencement of 

discharge. It must include:

(i) the facility name, address, and contact information as well as the dental 

license number of all practicing dentists at the location.

(ii) A description of the operation at the dental discharger including:

(A) the total number of chairs, 

(B) the total number of chairs at which dental amalgam may be present in the 

resulting wastewater;

(C) For existing sources, a description of any existing amalgam separators 

currently operated to include, at a minimum, the make, model, and 

manufacturers recommended frequency of container change. If no 

separators are currently employed, indicate none. For new sources, a 

description of any planned amalgam separators to include, at a minimum, 

the make, model, and manufacturers recommended frequency of container 

change.

(iii) For existing sources, statement of whether or not the facility currently 

employs the best management practices specified in 441.40(b).

(2) 90 Day Compliance Report. For existing sources, a compliance report must be 

submitted within [90 days after the final compliance date of this rule]. For new 

sources, a compliance report must be submitted within 90 days following 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 101 of 103

commencement of the introduction of wastewater into the POTW. The report 

must include: 

(i) the facility name, address, and contact information as well as the dental 

license number of all practicing dentists at the location

(ii) A description of the operation at the dental office including:

(A) the total number of chairs, and

(B) the total number of chairs at which dental amalgam may be present in the 

resulting wastewater

(C) A description of any existing amalgam separators currently operated to 

include, at a minimum, the make, model, and manufacturers recommended 

frequency of container change

(iii) Certification that the design and operation of separators meet the 

requirements specified in section 441.40 or 441.50, as applicable.

(iv) Certification that the facility is employing best management practices 

specified in section 441.40(b) or 441.50(b) as applicable.

(3) Periodic Monitoring Report. A periodic report of ongoing compliance must be 

submitted annually. The reports must include:

(i) the facility name, address, and contact information as well as the dental 

license number of all practicing dentists at the location,

(ii) If no changes have occurred since submission of the most recent 

compliance submission (e.g. 90 day compliance report or periodic monitoring 

report), 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 102 of 103

(iii) Certification that the design and operation of the separators meets the 

requirements specified in 441.40 or 441.50, as applicable and that the facility is 

employing the best management practices specified in 441.40(b) or 441.50(b), as 

applicable. 

(iv) If changes have occurred since submission of the most recent compliance 

submission (e.g. 90 day compliance report or periodic monitoring report), you 

must submit the updated information required for the 90 day compliance report as 

specified in x441.60(A)(2) of this subpart.

(b) If the dental discharger complies with the applicable requirements in 40 CFR part 403 and 

the monitoring and reporting requirements described above, in addition to the applicable 

PSES or PSNS in 441.40 or 441.50, the dental discharger may be considered a Dental 

Industrial User by the Control Authority; otherwise the Control Authority must treat the 

dental discharger as a Significant Industrial User (SIU) as defined in 40 CFR 403.3(v). 

Reports submitted to comply with this section must be signed by the responsible corporate 

officer as defined in 40 CFR 403 (12)(l).

(c) Dental dischargers must maintain on site and available for inspection (in either physical or 

electronic form) the following records for a period of three years from the date they are 

created:

(i) The Baseline Report required at 441.60(a)(1)

(ii) The 90 Day Compliance Report required at 441.60(a)(2)

(iii) The Periodic Monitoring Report required at 441.60(a)(3) 
*** E. O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

Page 103 of 103

(iv) Documentation including the date of each visual inspection of the 

amalgam separator(s) as specified in 441.40(c)(iv) or 441.60(d)(iii), 

including records of visual inspections of the amalgam separator to ensure 

that the device is not in bypass mode.

(v) Documentation specifying the date of amalgam retaining cartridge 

replacement in accordance with 441.40(c)(v) or 441.40(d)(iv); and

(vi) Records indicating the date of amalgam retaining cartridges are sent off 

site for proper disposal and the shipping address of the facility to which 

amalgam retaining cartridges are sent.