### EPA-821-R-08-014



# Health Services Industry Detailed Study

Dental Amalgam

August 2008

### i CONTENTS

Page

E XECUTIVE 

### S UMMARY



### ............................................................................................................... ES- 1

1. I NTRODUCTION 

### .................................................................................................................1-1

2. P ROFILE OF 

### D ENTAL 

### I NDUSTRY 

### ........................................................................................2-1

2.1 Number of Facilities ............................................................................................2-1 2.2 Revenues and Employees ....................................................................................2-3 2.3 Number of Companies .........................................................................................2-3

2.4 Number of Small Businesses ...............................................................................2-4 2.5 Ownership............................................................................................................2-5 2.6 Discharge Information .........................................................................................2-5

2.7 Financial Characteristics......................................................................................2-6 2.7.1 Liquidity...................................................................................................2-6

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

3. D ENTAL 

### M ERCURY 

### S OURCES AND 

### E NVIRONMENTAL 

### I MPACTS 

### ........................................3-1 3.1 Sources of Dental Amalgam in Wast ewater from Dental Facilities....................3-2 3.2 Environmental Impacts of De ntal Mercury Discharges.......................................3-2 3.3 Dental Mercury Treatment at POTWs.................................................................3-3

4. C URRENT 

### N ATIONAL



### , S TATE



### , AND 

### L OCAL 

### D ENTAL 

### M ERCURY 

### P ROGRAMS 

### ......................4-1 4.1 National Dental Amalgam Re quirements and Guidance.....................................4-1 4.1.1 Federal Requirements and Guidance .......................................................4-1

4.1.2 American Dental Association Guidance..................................................4-3 4.2 State Dental Amalgam Requirements and Guidance...........................................4-5 4.2.1 State Mandatory Programs.......................................................................4-5 4.2.2 State Dental Amalgam Guidance.............................................................4-9 4.3 Local Dental Amalgam Requi rements and Guidance..........................................4-9 4.3.1 Local Dental Amalga m Requirements.....................................................4-9 4.3.2 Local Dental Amalgam Voluntary Programs ........................................4-15 4.4 Common Elements Found in State and Local Programs ...................................4-22

5. E FFECTIVENESS AND 

### C OSTS OF 

### D ENTAL 

### BMP S



### , I NCLUDING 

### A MALGAM


### S EPARATORS 

### .....................................................................................................................5-1

5.1 Treatment Efficiencies and Sta ndards for Amalgam Separators .........................5-1 5.1.1 Standards for Amalgam Separators .........................................................5-1

5.1.2 Treatment Efficiencies.............................................................................5-2 5.2 Impacts of Dental BMPs, Includ ing Amalgam Separators, on POTW

Influent.................................................................................................................5-4 5.2.1 Summary of Dental BMPs.......................................................................5-4 5.2.2 Summary of Case Studies ........................................................................5-5 5.2.3 Considerations for Determining Impacts of BMPs on POTW Influent Mercury Levels ..........................................................................5-5

### CONTENTS (Continued)

Page

ii 5.3 Costs of Dental BMPs..........................................................................................5-9 5.3.1 BMP Program Costs to Stat e and Local Agencies...................................5-9

5.3.2 Costs to Facilities.....................................................................................5-9 5.3.3 Amalgam Recycling...............................................................................5-15

6. D ENTAL 

### M ERCURY 

### P ASS 

### -T HROUGH 

### A NALYSIS 

### ................................................................6-1

6.1 Number of Dentists..............................................................................................6-1 6.2 Mercury Discharge from Amalgam Rest orations and Amalgam Removal .........6-2 6.3 Determining Baseline Mercury Discharge to POTWs.........................................6-3

6.4 Potential Reduction from Installa tion of Amalgam Separators ...........................6-5 6.5 Annualized Costs for Amalgam Separators.........................................................6-6 6.6 Summary and Costs .............................................................................................6-7

7. R EFERENCES 

### .....................................................................................................................7-1

### iii LIST OF TABLES

Page

2-1 Number of Establishm ents by State (2005) ..................................................................... 2-1

2-2 Number of Dental Labo ratories and Offices.................................................................... 2-3

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

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

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

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

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

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

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

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

4-3 Best Management Pr actices by State ............................................................................... 4-7

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

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

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

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

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

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

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

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

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

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

5-4 Cost of Purchasing, Operating and Ma intaining Amalgam Separators ($2008) a 

### ......... 5-11

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

5-6 Summary of Cost Estimates........................................................................................... 5-14

### LIST OF TABLES (Continued)

Page

iv 5-7 Estimated Annual Cost for Amalgam Sepa rators by Size of Dent al Office ($2008) .... 5-15

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

6-2 Determining the Total Mercury Disc harge from Amalgam Restorations ....................... 6-2

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

6-4 Determining the Baseline Merc ury Discharge to Wastewater......................................... 6-4

6-5 Potential Reductions of Mercury to POTWs from Mandatory Installation of Amalgam Sepa rators........................................................................................................ 6-5

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

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

6-8 Number of Dental Facilities a nd Amalgam Separator Use by State................................ 6-8

### ES-1 E XECUTIVE 

### S UMMARY



### Across the United States, many States and municipal wastewater treatment plants (publicly owned treatment works (POTWs)) are work ing toward the goal of reducing discharges of mercury to POTWs. Many studies have been conducted in an attempt to identify the sources of mercury entering these PO TWs. According to the 2002 Mercury Source C ontrol and Pollution Prevention Program Final Report prepared for the National A ssociation of Clean Water Agencies (NACWA), dental clinics are the main source of mercury discharges to POTWs. A study funded by the American Dental Associatio n (ADA) estimated in 2003 that 50 percent of mercury entering POTWs was contributed by de ntal offices (Vandeven and McGinnis, 2005). EPA estimates that dentists discharge approximately 3.7 tons of mercur y each year to POTWs (see Section 6 of this document).

Sources of amalgam in dental wastewater include the placement of and removal of amalgam fillings (restora tions). Of the dental amalgam constituents, mercury is of greatest concern to human health because it is a persiste nt bioaccumulative toxic chemical. Mercury can

bioaccummulate three to ten times across each trophic level of the food chain. The major route for human exposure to mercury in wastewater discharges is through the consumption of mercury-contaminated fish.

Mercury discharged in dental wastewater is present in many forms, including elemental mercury bound to amalgam particulate, inorgani c (ionic) mercury, elemental mercury, and organic mercury (monomethyl mercury (MeHg) ) (Stone, 2002). The vast majority (>99.6 percent) of dental mercury di scharges are in solid form (e lemental mercury bound to amalgam particulate). While dissolved mercury composes a small portion of total mercury in dental office wastewater, some studies have in dicated high levels of dissolved mercury in dental wastewater, and that dissolved mercury concentrations can be high enough to violate local mercury discharge limits (Stone, 2004).

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

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

Researchers have detected concentrations of Me Hg in dental wastewater that are orders of magnitude higher than background MeHg concentr ations measured in environmental samples (i.e., open oceans, lakes, and rainfall) (Stone , 2002). Although the MeHg concentrations are small compared to total mercury concentrations in dental wastewater, MeHg is particularly toxic to humans due to its ability to bi oaccumulate in fish (WI DNR, 1997).

EPA estimates there are approximately 120,000 dental offices that use or remove amalgam in the United States – almost all of wh ich discharge their wastewater exclusively to POTWs. Most dental offices currently use some type of basic filtration system to reduce the amount of mercury solids passing in to the sewer system. However, best management practices and the installation of amalgam separators, which ge nerally have a removal efficiency of at least 95 percent, have been shown to reduce disc harges even further. A 2002 study funded by the National Association of Clean Water Agencies (NACWA) (See: DCN: 04225) concluded that the use of amalgam separators results in reduc tions in POTW influent concentrations and biosolids mercury concentrations. However, the NACWA study found that the use of amalgam separators does not always result in reductions in POTW effluent. Since the mercury in dental amalgam often reaches POTWs as larger particulates, it is likely to be removed in the grit

### ES-2 chambers or with the biosolids and not be disc harged with the effluent. Thus, reductions in dental office amalgam discharges may result in reductions in the mercury content of POTW sludges (grit and biosolids), and may not result in reductions in mercury concentrations in

POTW effluent.

ADA provides guidance documents for its members and the general public for the management and disposal of dental amalgam and amalgam waste. These include information regarding proper recycling of am algam waste and practical guidelines for integrating best management practices (BMPs) into dental practices. On October 2, 2007, the ADA updated its BMPs to include the use of amalgam separa tors. ADA also provides advice for successful integration of BMPs into practices and offices, a directory of national de ntal waste recyclers, recommendations for safe preparation and pl acement of amalgam restorations, safety information for managing mercury spills, and ad vice on the purchase, installation and operation of amalgam separators (ADA, 2007). The ADA-defi ned BMPs are recognized as the industry

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

State and local governments have implem ented mandatory and voluntary programs to reduce dental mercury discharges. Specifically, 11 States and at le ast 19 localities have mandatory pretreatment programs that require th e use of dental mercury amalgam separators. Additionally, at least four St ates and six POTWs have volunt ary programs to reduce mercury discharges from dental offices though success rate s for the voluntary programs vary greatly.

In this document, EPA has compiled inform ation on current mercury discharges from dental offices, best management practices (BMPs), and amalgam separators. For amalgam separators, EPA has looked at the frequency with which they are currently used; their effectiveness in reducing discharg es to POTWs; and th e capital and annual co sts associated with their installation and operation. EPA has also conducted a POTW pass-through analysis on mercury for the industry.

EPA does not think national, categorical pr etreatment standards for dental mercury discharges are appropriate at this time. While this is a possibility for the future, EPA has

identified a number of successful voluntary programs demonstra ting that there are opportunities for pollution prevention and adoption of BMPs w ithout federal regulation. Moreover, the dental industry is working towards volun tarily reducing its me rcury discharges. Also, due to mercuryfree fillings and improved overall dental health, th e use of mercury in dentistry is decreasing in

the U.S.

### 1-1 1. I NTRODUCTION



### Under the Clean Water Act (CWA), EPA establ ishes national regulations (called effluent limitations guidelines and standards) to reduce di scharges of pollutants from industries to surface waters and publicly owned treatment works (P OTWs). Section 304(g) and 307(b) of the CWA requires EPA to review industries consisting entirely or almost enti rely of indirect discharging facilities that are not currently subject to pretr eatment standards to identify potential candidates for pretreatment standards development. This includes pretreatment standards for categories of dischargers that discharge pollu tants not susceptible to trea tment by POTWs or that would interfere with the operation of POTWs. Using ava ilable data, EPA reviews the types of pollutants in an industry’s wastewater. Then, EPA review s the likelihood of those pollutants to pass through a POTW and finally considers whether the pollutant discharges ar e already adequately controlled by general pretreatment sta ndards and/or local pretreatment limits.

Every other year EPA publishes a final Efflue nt Guidelines Program Plan as required by CWA Section 304(m). The plan addresses both categories with large numbers of direct discharging facilities and categories consisting entirely or almost entirely of indirect discharging facilities. EPA publishes a draft plan to give th e public an opportunity to comment on the plan

before it is final. EPA selected the health servi ces industry for further analysis in the 2006 Plan (EPA, 2006), based in part on public comments con cerning the discharge of mercury from dental

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

• 

### What are the current industry practices fo r disposing of dental mercury, to what extent are each of these practices applied, and what factors affect the use of these practices?

• 

### What are the federal, state, or local requirements or guidanc e for disposal of dental mercury?

• 

### How are control authorities currentl y limiting dental mercury discharges?

• 

### Do POTWs report pass-through or interf erence problems related to dental mercury discharges?

• 

### What technologies are available (1) as alte rnatives to wastewater disposal and (2) to control discharges? How effective are these technologies?

• 

### What best management practices (BMPs) ar e used as alternatives to wastewater disposal and/or to control discharg es? How effective are these practices?

• 

### What are the costs of the identi fied technologies and/or BMPs?

This report describes EPA’s analysis of dent al mercury discharges and is organized into the following sections:

### 1-2 • 

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

number of dental offices and laborator ies, the number of small businesses, discharge information, and fi nancial characteristics;

• 

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

• 

### Section 4 describes national, state, and local mandatory and voluntary programs to reduce mercury wastewater di scharges from dental offices;

• 

### Section 5 describes the e ffectiveness and costs for dental mercury BMPs and amalgam separators; and

• 

### Section 6 describes EPA’s estimate of th e potential reductions in dental mercury discharges to receiving streams followi ng installation of amalgam separators.

### 2-1 2. P ROFILE OF 

### D ENTAL 

### I NDUSTRY



### This section presents industry profile in formation using the North American Industry Classification System (NAICS) codes and the Sta ndard Industrial Classifi cation (SIC) codes. The

U.S. Census Bureau classifies information by NAICS codes and EPA classifies discharge information (TRI and PCS databa se information) by SIC code.

Dental laboratories fall under NAICS 339116, with the definition:

“This U.S. industry comprises establishmen ts primarily engaged in manufacturing dentures, crowns, bridges, and orthodontic appliances customized for individual application.” http://www.census.gov/epcd/ec97/def/339116.TXT

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

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

“This industry comprises establishments of health practitioners having the degree of D.M.D. (Doctor of dental medicine), D.D.S. (Doctor of dental surgery), or D.D.Sc. (Doctor of dental science) primarily engaged in the independent prac tice of general or specialized dentistry or dent al surgery. These practitione rs operate private or group practices in their own offices (e .g., centers, clinics) or in the facilities of others, such as hospitals or HMO medical centers. They can provide either comprehensive preventive, cosmetic, or emergency care, or specia lize in a single field of dentistry.” http://www.census.gov/epcd/ec97/def/621210.TXT

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

2.1 Number of Facilities

Table 2-1 provides a comprehensive listing of es tablishments by state for NAICS 339116 (Dental Laboratories) and 621210 (Dental Offices). Based on 2005 County Business Patterns data, there are 7,225 dental laboratories a nd 122,918 dental offices operating nationwide (Census, 2005a). According to the 2002 Cens us, there were 7,096 dental laboratories and 118,305 dental offices. According to the 1997 Census , there were 7,609 dental laboratories and 114,178 dental offices (Johnston, 2005). Table 2-2 shows the industry changes over time.

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

State NAICS 339116 Dental Laboratories NAICS 621210 Dental Offices

Alabama 107 1,417

Alaska 16 307

Arizona 153 2,209

Arkansas 58 933

California 1,011 19,005

Colorado 153 2,366

Connecticut 80 1,732

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

State NAICS 339116 Dental Laboratories NAICS 621210 Dental Offices

Delaware 8 243

District of Columbia 2 315

Florida 566 6,733

Georgia 247 3,024

Hawaii 38 686

Idaho 59 656

Illinois 318 5,639

Indiana 139 2,334

Iowa 69 1,077

Kansas 55 1,016

Kentucky 73 1,586

Louisiana 97 1,527

Maine 27 478

Maryland 108 2,483

Massachusetts 113 3,050

Michigan 208 4,353

Minnesota 134 1,922

Mississippi 47 846

Missouri 144 2,153

Montana 38 414

Nebraska 49 790

Nevada 73 883

New Hampshire 32 560

New Jersey 219 4,546

New Mexico 38 593

New York 469 9,017

North Carolina 228 2,720

North Dakota 10 259

Ohio 232 4,357

Oklahoma 71 1,325

Oregon 143 1,825

Pennsylvania 216 5258

Rhode Island 30 412

South Carolina 63 1,368

South Dakota 18 267

Tennessee 128 2,110

Texas 377 7,597

Utah 117 1,418

Vermont 18 263

Virginia 177 2,845

Washington 276 3,183

### 2-3 Table 2-1. Number of Establishments by State (2005)

State NAICS 339116 Dental Laboratories NAICS 621210 Dental Offices

West Virginia 26 573

Wisconsin 135 2,023

Wyoming 12 222

Total U.S. 7,225 122,918

Source: Census, 2005a.



### Table 2-2. Number of Dental Laboratories and Offices

NAICS Code SIC Code Number of Facilities

in 1997 Number of Facilities

in 2002 Number of Facilities

in 2005

339116: Dental

Laboratories 8072: Dental

Laboratories 7,609 7,096 7,225

621210: Offices of

Dentists 8021: Offices and

Clinics of Dentists 114,178 118,305 122,918

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



### 2.2 Revenues and Employees

Table 2-3 lists the number of establishments, total revenues, total number of paid employees, average revenue, and average number of employees per establishment based on the 2002 Census data. Average revenue and the averag e number of paid employees were determined by dividing total revenue and to tal paid employees by the tota l number of establishments, respectively.

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

NAICS Number of

Establishments Revenues ($1,000) Paid Employees Average Revenue ($1,000) Employees per

Establishment

339116: Dental

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

621210: Dental

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

Sources: Census, 2004 and 2005b.



### 2.3 Number of Companies

Table 2-4 shows the number of establishments, total firms, and single- and multi-unit firms. For dental offices, the 2,461 multi-unit firms comprise 7,464 total establishments; specifically, there are 1,542 firm s with two establishments, 40 2 firms with three to four establishments, 96 firms with five to nine establishments, and 41 fi rms with 10 or more establishments (Census, 2005c).

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

NAICS Number of Firms Number of

Establishments Single-Unit Firms Multi-Unit Firms

339116: Dental Laboratories 6,925 7,096

— —

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

Sources: Census, 2004 and 2005c.



### 2.4 Number of Small Businesses

Table 2-5 lists the Small Business Administrati on (SBA) size standard for each NAICS industry and the number of establishments that m eet these criteria. Dental laboratories have a size standard of 500 employees, while dental o ffices have a size standard of $6.5 million in average annual receipts (SBA, 2006).

Table 2-5. Small Businesses (2005)

NAICS Size Standard Total Definitely

Small Possibly

Small Best Estimate

Small % Small

339116: Dental

Laboratories 500 employees 7,096 7,086

— 7,086 99.9%

621210: Dental

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

Sources: Census, 2004 and 2005b.



### For dental laboratories, 2004 Census data list 7,086 establishments with fewer than 500 employees and three establishments with more than 500 employees (Census, 2004). 1 

### Thus, EPA determined that 7,086 firms are below the SBA th reshold. Therefore, 99.9 percent of dental laboratories (NAICS 339116) qualify as small businesses.

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

EPA classified an establishment in the “definitel y small” category if it operated for the entire year and was in a revenue group where the upper limit was less than $6.5 million. The SBA size standard of $6.5 million falls within the rang e of the $5 million to $9.99 million revenue group.
As a result, some but not all of the 149 estab lishments in that revenue group are small. EPA assumed that the companies were evenly distri buted within the revenue group and prorated the company count accordingly. EPA estimated the number of “possibly small” establishments by multiplying 149 establishments by the ratio of the number of revenue units below the SBA threshold to the total number of revenue units in the range —

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

1 The discrepancy in the total number of establishments can be attributed to the fact that “some payroll and sales data for small single-establishment companies with up to 20 employees (cutoff varied by industry) were obtained from administrative records of other Government agencies rather than from census report forms. These data were then used in conjunction with industry averages to estim ate statistics for these small establishments. This technique

was also used for a small number of other establishments whose reports were not received at the time data were tabulated.” (Census, 2004)

### 2-5 — for a total of 45 establishments. EPA also in cluded the number of companies that did not operate for all of 2005 (9,656) in the “possibly small” category in order not to underestimate the

number of small entities. EPA assumed that the proportion of establishments that did not operate for an entire year and also qualified as small wa s equal to the proportion of establishments that qualified as small in the overall population: 98.8 percent, or 9,540 establishments (Census, 2005b).

Based on the census information presented in this section, dental la boratories and dental offices are nearly all small businesses.

2.5 Ownership

Among the 118,305 total dental office establishments, 2002 Census data list 62,821 corporations, 50,638 individual propr ietorships, 4,778 partnerships, and 68 other forms of legal organization for dental offices. Ownership data for dental laboratories are not available at this time (Census, 2005d).

2.6 Discharge Information

Based on information contained in the TRI a nd PCS databases, dental facilities are small establishments, and few, if any, de ntal laboratories or dental offices/clinics are direct dischargers. No dental laboratories (SIC 8072) or dental offices/clinics (SIC 8021) reported releasing toxic chemicals to any media to TRI for 2004 (TRIReleases2004_v01) . A facility is exempt from TRI reporting if it has less than 10 employees or if its chemical releases are below the TRI reporting thresholds; the TRI reporting threshold for mercury and mercury compounds is 10 pounds per

year.

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

laboratories or dental offices/c linics. EPA reviewed PCS data contained on EPA’s Envirofacts Web page to verify that discharg es from dental offices and dent al laboratories were not reported

to PCS. EPA identified nine dental offices/c linics that report to PCS (2007 Envirofacts information). Seven of these facilities were classified as minor dischargers. Permitting authorities are not required to report discharge in formation for minor facilities to PCS; therefore discharges for these seven fac ilities were not included in PCSLoads2004_v02 . Two of the facilities that report to PCS were classified as ma jor dischargers. However, the facilities did not have permit limits; therefore PCS does not contai n measurement data for those facilities. EPA

also identified one dental labo ratory in PCS (2007 Envirofacts information). However, this facility is classified as a minor discharger with no discharge da ta in PCS, and therefore is not

included in PCSLoads2004_v02

.

The lack of information in TRI and PCS a bout dental industry wa stewater discharges confirms that nearly all dental facilities are small, indirect dischargers. These results are

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

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

### 2-6 2.7 Financial Characteristics

This subsection describes the financial charact eristics of the dental industry as measured by liquidity and profit before taxes.

2.7.1 Liquidity

Liquidity measures the ability of an industry to meet current financial obligations without having to convert assets to cash with a loss in valu e. A current ratio is calculated as total current assets divided by total current liabilities. Table 2-6 summarizes the current ratio for dental offices and dental laboratories for 2006 (RMA , 2007). Several differences between the groups are evident. With the exception of dental offi ces with sales in excess of $25 million, dental offices are illiquid. The overall current ratio for the industry in 2006 is 0.9 and the current ratio of dental offices with less than $25 million in revenues ranges from 0.7 to 0.9. This indicates that, at the time the balance sheet was constructe d, the dental office owed more to its creditors

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

the 2007 edition Almanac Financial of Busi ness and Industrial Ratios indicates that dental offices are liquid and have suffici ent assets to cover their current debts with a small cushion, and reports a ratio of 1.2 in 2004 (Troy, 2007). The 2007 Almanac is based on a sample of 62,347 enterprises while RMA (2007) is based on 763 income statements.

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

Revenues ($Millions)

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

339116: Dental

Laboratories 1.7

— 2.7

— — — —

621210: Dental

Offices 0.9 0.8 0.9 0.7 0.9 0.8 1.1

Source: RMA, 2007.



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

laboratories show a much health ier current ratio of 1.7, indicati ng a greater ability to meet current obligations. (RMA does not show data when there are fewer than 10 annual statements in the subcategory.)

2.7.2 Profit Before Taxes

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

of costs and revenues. Table 2-7 shows a 10.4 percent profit before taxes for dental offices and a 5.0 percent profit for de ntal laboratories.

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

Revenues ($Millions)

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

339116: Dental

Laboratories 5.0

— 5.8

— — — —

621210: Dental

Offices 10.4 11.7 10.4 7.1 7.7 6.3 6.2

Source: RMA, 2007.

### 3-1 3. D ENTAL 

### M ERCURY 

### S OURCES AND 

### E NVIRONMENTAL 

### I MPACTS



### The EPA Office of Compliance’s Sector No tebook for the Healthcare Industry identified mercury as the major pollutant of concern (POC) fo r wastewater discharges from dental facilities (see EPA-HQ-OW-2004-0032-0729). Sources of amal gam in dental wastewater include the placement of amalgam fillings and removal of am algam during restorations. Other constituents of dental amalgam include metals such as silver , tin, copper, zinc, indium , and palladium. Of the dental amalgam constituents, mercury is of greate st 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. Fo r wastewater mercury discharges, the major route for human exposure is the consumption of mercury-contaminated fish.

While mercury used in U.S. dental offices accounts for only a small percentage of the total mercury discharged to air and water each ye ar, mercury in the form of dental amalgam is among the largest sources of mercury found in wastewater influent reaching POTWs. The American Dental Association (ADA) estimates that up to 50 percent of the mercury entering POTWs originates in dental offices (Vandeve n and McGinnis, 2005). Recent data compiled from across the country indicate that varying amounts of the mercury in wastewater reaching POTWs originates from dental offices:

• 

### The East Bay Municipal Utility District (EBMUD) of Oakland, CA, estimates that dental offices account for 34 percent of the mercury influent loading to wastewater treatment plants (EBMUD, 2007);

• 

### Dental clinics contribute 11 to 14 percent of the mercury loading to local sanitary districts in Seattle, WA (Stone, 2004);

• 

### Dental clinics account for almost 50 percent of the mercury in wastewater in Palo Alto, CA (Palo Alto, 2007); and

• 

### A study by the Association of Metropolit an Sewerage Agencies (AMSA) — now

the National Association of Clean Wa ter Agencies (NACWA) — found that dental offices account for an average of 35 percent of the mercury influent to POTWs (AMSA, 2002).

Due to the increased concern regarding mercury in the environment, several U.S. industries have significantly decreased mercury usage since the 1980s (Vandeven and McGinnis, 2005). Although dentists have al so reduced their mercury use, as of 1999, amalgam was still widely used for restorations (66 million am algam restorations in 1999) (Stone, 2004). ADA predicts that use of amalgam will continue to decrease due to various factors such as the introduction of improved filling material, overall decrease in tooth decay and earlier detection of tooth decay (EPA, 2007a). In 2007, TheWealthyDentis t.com, a website and weekly newsletter for dentists, surveyed dentists to determine amalgam use. The survey found that 52 percent of dentists do not place amalgam fillings (The Wealthy Dentist, 2007).

The remainder of this section describe s the wastewater sources of amalgam, environmental impacts of dental mercury, a nd treatment of dental mercury at POTWs.

### 3-2 3.1 Sources of Dental Amalgam in Wa stewater from Dental Facilities

Amalgam used in dental practices is typi cally 50 percent mercury mixed with a powder of silver, tin, copper, and sometimes zinc, indi um, or palladium. Raw materials for dental amalgam are liquid mercury and a metal powder mi xture, often supplied in capsules. In these capsules, the mercury and metal pow ders are kept separate until the dentist is ready to complete a restoration. When the dentist mixes (triturates) the mercury and powder, the mercury dissolves the powdered metals and a series of intermetallic compounds (e.g., Ag 3 

### Sn, Ag 2 

### Hg 3 

### , Sn 8 

### Hg) are formed (Vandewall, 2007).

Sources of amalgam in dental wastewater include waste amalgam from fillings and amalgam removed during restorations. When filli ng a cavity, dentists will always overfill the tooth cavity so they can carve the filling into proper sh ape (Columbia, 2005). The excess amalgam is typically rinsed into a chair-side drai n. In addition to filli ng new cavities, dentists

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

the chair-side drain.

3.2 Environmental Impacts of Dental Mercury Discharges

Mercury discharged in dental wastewater is present in many forms, including elemental mercury bound to amalgam particulate, inorgani c (ionic) mercury, elemental mercury, and organic mercury (monomethyl mercur y, or MeHg) (Stone et al., 2002). Table 3-1 presents the mean concentrations of mercury species measured in wastewater samples collected at the chair. The vast majority (>99.6 percent) of dental me rcury discharges are in solid form (elemental mercury bound to amalgam particulate).

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

Mercury Form Measured Concentration Percent of Total Mercury

Total mercury 21.438 milligrams/liter (ppm) 100.0%

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

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

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

Hg0 (elemental mercury bound to amalgam particulate) 21.360 milligrams/liter (ppm) 99.636160%

Source: Stone, 2004.



### While dissolved mercury makes up a small portio n of the total mercury in dental office wastewater, there is increasing interest in th e causes of dissolution a nd the extent to which dissolved mercury is present in dental office wast ewater. Some studies have indicated high levels of dissolved mercury in dental wastewater, and that dissolved mercury concentrations can be high enough to violate local mercur y discharge limits (Stone, 2004).

Dissolved mercury is a concern because it can be converted to MeHg by bacteria, such as Desulfobacteraceae and Desulfovibrionaceae, that are present in wastewater (ACS, 2008).

Researchers have detected concentrations of Me Hg in dental wastewater that are orders of magnitude higher than background MeHg concentr ations measured in environmental samples

### 3-3 (i.e., open oceans, lakes, and rainfall). Concentr ations of MeHg in de ntal wastewater ranged from 0.90 to 26.77 mg/L, while concentrations in environmental samples ranged from 0.05 to 10.0 ng/L (Stone et al., 2002). Res earchers have concluded that sulfate-reducing bacteria are responsible for the presence of methylmercury in dental wastewater. Ho wever, it is not clear whether methylation occurs in the patient’s mouth or in the discharge stream (ACS, 2008). Although the MeHg concentrations are small compared to total mercury con centrations in dental wastewater, MeHg is particularly toxic to human s due to its ability to bioaccumulate in fish. When humans consume MeHg, it targets the nervous system and can hinder a person’s ability to walk, talk, see, and hear. Extreme cases of Me Hg poisoning can result in coma or death (WI DNR, 1997).

3.3 Dental Mercury Treatment at POTWs

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

because it can affect the POTWs’ ability to remove mercury from influent wastewater. Solid mercury particles will likely settle out of solution and adsorb to the wastewater treatment sludge. However, dissolved mercury can pass through tr eatment operations and enter surface waters. EPA’s 50 POTW Study (EPA, 1982) estimates that PO TWs can effectively remove 90 percent of total mercury (solid and dissolved) from wast ewater. However, other studies conducted by Metropolitan Council Environmental Services (MCES) in 1995 and NACWA from 2002 through 2006 have shown total mercury removals of 95 to 99 percent (Vandeven and McGinnis, 2005; AMSA, 2002; NACWA, 2007).

Mercury that partitions to wastewater sludge may be incine rated or disposed of in a landfill. Unbound mercury is highly volatile a nd can easily evaporate into the atmosphere. However, because the majority of dental merc ury is bound to solid particles, it will not likely volatilize to the atmosphere unle ss the wastewater sludge is inci nerated. Once in the atmosphere, mercury can be deposited into lakes and streams via precipitation (WI DNR, 1997).

### 4-1 4. C URRENT 

### N ATIONAL 

### , S TATE 

### , AND 

### L OCAL 

### D ENTAL 

### M ERCURY 

### P ROGRAMS



### This section discusses nationa l, state, and local programs to reduce discharges of dental mercury. Currently, there are no federal regulat ory requirements that specifically address discharges of dental mercury to wastewater. Th ere are, however, federal requirements to control dangers of exposure to dental mercury. The ADA has recently adopted BMP guidance that

includes the recommendation that dentists use am algam separators. Requirements for controlling discharges of dental mercury to wastewater are set at the state a nd local level. Currently 11 states have established mandatory state-wide program s. EPA has also reviewed requirements for 19 local mandatory programs spanning 6 states. The re mainder of this section is organized into the following subsections:

• 

### Section 4.1 discusses national programs;

• 

### Section 4.2 summarizes state programs;

• 

### Section 4.3 summarizes lo cal programs; and

• 

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

4.1 National Dental Amalgam Requirements and Guidance

This subsection summarizes national program s, including federal regulations and federal and non-federal guidance, for the use a nd disposal of dental amalgam.

4.1.1 Federal Requirements and Guidance

Federal agencies that have established regulations for dental amalgam include the Occupational Safety and Health Administration (OSHA) and the Food and Drug Administration (FDA). Both federal regulations, however, focu s on aspects of dental amalgam related to employee and consumer exposure and do not ad dress discharges of dental amalgam to

wastewater. This subsection also discusses EPA’ s guidance and other efforts to reduce releases of mercury to the environment, including discharg es of dental amalgam. EPA has not established national regulations for dental amalgam.

Occupational Safety and Health Administration

OSHA’s authority regarding dental amalga m is limited to employee exposure resulting from handling or use of hazardous chemicals in the workplace. Dental amalgam is considered

non-hazardous to consumers who receive dental re storations because the amalgam is considered benign once it is installed. However, workers handling amalgam have a greater potential for exposure than consumers, because dental work ers handle liquid mercury while they prepare mercury amalgam restorations. For that reason, dental amalgam is clas sified as a hazardous

chemical under OSHA’s Hazard Communication St andard. Workers who handle amalgam alloy are entitled to protection under this standard, incl uding the receipt of training and hazard information. OSHA’s focus on dental amalgam is unrelated to the disposal of spent amalgam (OSHA, 1997).

Food and Drug Administration

FDA regulates dental amalgam under th e Federal Food, Drug, and Cosmetic Act (FFDCA). The FFDCA classifies dental mercury as a Class I medical device and amalgam alloy

### 4-2 as a Class II medical device (see Title 21, Code of Federal Regulations , sections 872.3700 and 872.3050). Class I medical devices are subject to ex tensive safety regulations for use. Class II medical devices are subject to additional spec ial controls for use (Anderson, 2007). FDA’s and CDC’s focus on dental amalgams is on the health risks to dentists, dental workers, and patients rather than the disposal of spent amalgam. Acco rding to FDA, dental amalgams contain mercury, which may have neurotoxic effects on the nervou s systems of developing children and fetuses (FDA, 2008).

U.S. Environmental Protection Agency

There are no federal effluent limitations gui delines for mercury discharges from dental offices and dental laboratories, but EPA and its regional offices work closely with states and communities to develop strategies for reducing effluent discharges of mercury, including discharges from dental facilities. For exam ple, EPA’s Environmental Technology Verification Program studied amalgam separators to determine effectiveness (Grubbs, 2003). In addition, EPA regional offices participate in seminars a nd workshops with local organizations and other federal agencies to evaluate risks, devel op recommendations, disseminate information, and communicate with the public regard ing a wide range of mercury-a ssociated issues. For example, EPA Region 4 participated in the Project Team on Consumption Advisories for Mercury in Gulf

of Mexico Marine Fish. Als o, EPA Regions 5 and 8 as well as EPA Headquarters have participated in the activities listed below to limit mercury discharge from dental facilities.

• 

### Region 5. EPA and Environment Canada, working through the Great Lakes Binational Toxics Strategy, created a Merc ury Workgroup that promotes activities that will reduce mercury releases to the Great Lakes Basin. In addition to Environment Canada EPA’s Region 5, th is workgroup includes representative states, environmental organizations, and the Council of Great Lakes Industries. The Workgroup’s review of mercury releases in the Great Lakes area has focused on air emissions. As a result, the Wor kgroup has not collected trend data on mercury releases to water. The Workgroup has reviewed information on BMPs and successful voluntary and regulatory a pproaches used in state and local programs, including dental amalgam reduction programs in King County, WA; Toronto, ON; Duluth, MN; and Cleveland, OH (EPA, 2003). In addition, the Workgroup has not quantified reductions in mercury use or reductions in discharge of dental amalgam to wastewater.

• 

### Region 8

. EPA Region 8 developed a draft Me rcury Control Strategy to help POTWs control mercury pollution problems from commercial, non-significant industrial users, including dental facilitie s. This draft Strategy includes detailed information on the development of BMPs, amalgam separators, and other removal and filtration devices, as well as other background information regarding dental amalgam control approaches (EPA, 2005).

• 

### EPA Headquarters (Office of Solid Waste)(OSW) . OSW recommends four specific actions to manage amalgam waste at dental facilities. The first letters of each action form the acronym G.R.I.T.

### 4-3 EPA Office of Solid Waste Recommendation s for Dental Amalgam Waste Management

G Grey Bag It Discard any amalgam wastes into a grey bag. Never dispose of dental amalgam wastes in medical red bags or in your office trash containers

R Recycle It Select a responsible dental amalgam recycler who will manage your waste amalgam safely to limit the amount of mercury which can go back into the environment.

I Install It Install an amalgam water separator in the office to capture up to 99% of the mercury leaving a dental office through drains. This is the KEY to success.

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

Source: David Carver, EPA/OSW



### Disposal of mercury-containing waste is regulated under the Res ource Conservation and Recovery Act (RCRA). A mercur y-containing waste can be cons idered hazardous in two ways: 1) as a listed waste; or 2) as a characteristic waste. There are some source-specific hazardous wastes that are listed due to mercury; however, dental amalgam wastes ar e not listed in 40 CFR Part 261 Subpart D. A waste can be defined as a ch aracteristic hazardous wa ste if it exhibits the toxicity characteristics for mercury. This can oc cur when a sample of a waste contains enough mercury to exceed the regulatory threshold of 0.2 mg/l (or 0.2 ppm) when subjected to specific leach test known as the TCLP (Toxicity Ch aracteristic Leaching Pr ocedure; see 40 CFR §261.24). Persons who generate hazardous waste, su ch as a waste that exhibits the hazardous characteristics for mercury, are subject to speci fic requirements for the proper management and disposal of that waste. The federal RCRA regulations differ depending upon how much hazardous waste is generated per site per month. Most dentists generate less than 100 kg of nonacute hazardous waste per month and less than 1 kg of acute hazardous waste per month, and are therefore classified as “Conditionally Exempt Small Quantity Generators” (CESQGs). CESQGs are not subject to most of the RCRA hazardous waste requirements, provided the waste is otherwise managed properly. However, some states have additional requir ements for CESQGs or do not exempt CESQGs from all requirements (HERCenter, 2008).

4.1.2 American Dental Association Guidance

The most widely known national voluntary program is the “Best Management Practices for Amalgam Waste” developed and approved by th e ADA Board of Trustees. This program was first published in January 2003 and updated in 2007 to include amalgam separators. All state and local voluntary programs are base d on or derived from the guidan ce provided in the ADA BMPs.

ADA provides guidance documents for its members and the general public for the management and disposal of dental amalgam and amalgam waste. These include information regarding proper recycling of amal gam waste and practical guidelines for integrating BMPs into dental practices. ADA also provide s advice for successful integrati on of BMPs into practices and offices, a directory of national de ntal waste recyclers, recommendations for safe preparation and placement of amalgam restorations, safety inform ation for managing mercury spills, and advice on the purchase, installation, and operation ofamalgam separators (ADA, 2007a). The ADAdefined BMPs are recognized as the industry standard. Table 4-1 lists the ADA BMPs for amalgam waste.

### 4-4 Table 4-1. ADA BMPs fo r Dental Amalgam

Focus Best Management Practice

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

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

• Use line cleaners that minimize the dissolution of amalgam.

• Do not use bleach or chlorine-containin g cleaners to flus h wastewater lines.

• Because amalgam waste may be mixed with body fl uids or other potentially infectious material, use protective equipment such utility gloves, masks, and protective eyewear when handling it.

• Check with city, county, or local waste authorities to get in touch with an amalgam waste recycler for any special requirements that may exist in th e area for collecting, st oring, and transporting amalgam waste.

• Store amalgam waste in a covered plastic container labeled “Amalgam for Recycling” or as directed by the recycler.

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

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

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

• Recycle used disposable amalgam capsules.

• Do not put disposable amalgam capsules in biohazar d containers, infectious waste containers (red bags), or regular garbage.

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

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

• Place unused non-contact amalgam in a silver or gray storage contai ner or a storage container with silver or gray label (keep cont ainers sealed at all times).

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

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

• Recycle teeth that contain amalgam restorations af ter confirming with the recycler that they will accept extracted teeth with amalgam restorations.

• Do not dispose of extracted t eeth that contain amalgam restor ations in biohazard containers, infections waste containers (red bags), sharps containers, or regular garbage.

• Do appropriately disinfect extracted teeth that contain amalgam restor ations (e.g., 10 minutes in a 1:10 bleach-to-water solution).

• Place unused contact amalgam in a silver or gray storage container or a storage container with silver or gray label (keep cont ainers sealed at all times).

Chair-side

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

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

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

• Place disposable chair-side traps an d the contents of reusable chair-s ide traps in a silver or gray storage container or a storage container with a silv er or gray label (keep containers sealed at all times).

Amalgam

separators • Select an amalgam separator that complies with ISO 11143.

• Follow the manufacturer’s recommendations fo r maintenance and r ecycling procedures.

Other amalgam

collection

devices • Recycle contents retained by the vacuum pump filter, amalgam separator, or other amalgam collection device that may be us ed, if they contain amalgam.

• Do not rinse vacuum pump filters containing amalgam, amalgam separator canisters, or other amalgam collection devices that may be used over drains or sinks.

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

• Place disposable vacuum pump filters and the contents of reusable vacuum pump filters in a silver or gray storage container or a stor age container with silver or gray label (keep containers sealed at all times).

### 4-5 Table 4-1. ADA BMPs fo r Dental Amalgam

Focus Best Management Practice

Bulk

elemental

mercury • Recycle bulk mercury.

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

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

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

available.

Source: ADA, 2007a.



### 4.2 State Dental Amalgam Re quirements and Guidance

This subsection describes state mandat ory and voluntary programs for amalgam discharges from dental facilities.

4.2.1 State Mandatory Programs

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

dental facilities:

• 

### Connecticut;

• 

### Louisiana;

• 

### Maine;

• 

### Massachusetts;

• 

### New Hampshire;

• 

### New Jersey;

• 

### New York;

• 

### Oregon;

• 

### Rhode Island;

• 

### Vermont; and

• 

### Washington.

States typically use the vo luntary BMPs developed by ADA described above as the basis for their dental mercury discharg e regulations. As a result, the state requirements share several

common elements. Table 4-2 summarizes the elements of the va rious state regulations, including the types of requirements included and the met hods used to demonstrate compliance with the regulations. Table 4-3 compares the state BMP requirements to the ADA BMPs.

Table 4-2. Summary of Elements of State Requirements

Element Examples from State Requirements

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

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

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

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

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

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

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

### 4-6 Table 4-2. Summary of Elements of State Requirements

Element Examples from State Requirements

Operation specifications for amalgam separators • Must be operated at all times when dental procedures are performed (CT).

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

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

Method for demonstrating compliance • Submit separator certification to state e nvironmental agency (CT, MA, ME, NJ).

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

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

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

Compliance tracking • DEP inspections (CT).

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

Sources: (CTDEP, 2006; MassDEP, 2007; ); (MEDEP, 2005); (MADEP, 2007); (NHDES, 2002); (NYDEC, 2007); (Oregon, 2007); (RIDEM, 2007); (VTDEC, 2006); (Walsh, 2007). a — In several states, if a facility has an amalgam separator in operation prior to implementation of the state law, then the state will allow the facility to continue operatin g that separator at its current efficiency. Only newly installed separators are required to meet ope rating efficiencies of 98 and 99 percent.



### In addition to the state re quirements summarized in Table 4-2 and 4-3, New Mexico and Minnesota have proposed legislation for dental mercury controls and are awaiting approval. The bills would require all dental offices to insta ll amalgam separators (Walsh, 2007). As of August 2008, EPA has not found any information indicati ng that these bills have been enacted.

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

• 

### Alabama. In 2004, the Alabama state legislat ure began debate on two bills designed to regulate the use of mercur y in dental offices: HB 495, Mercury Amalgam Filling, and HB 665, Bill to Require Dentists to Provide Information about Mercury or Mercury Amalgam to Patien ts. It appears that both of these bills

failed to clear the House and were ta bled in the House Health Committee (ALISON, 2007).

• 

### Arkansas. The Mercury Poisoning Reduction Ac t of 2003 required the Arkansas Department of Environmental Quality to develop a plan for reducing mercury pollution from dental proce dures and implement a mandatory program for dental offices by July 1, 2004 (Arkansas, 2003). However, EPA could not find

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

• 

### California. In 2005, Assembly Bill 966, which would establish standards related to amalgam in dental and related services , passed the state Senate by a vote of 51 to 28 but was vetoed by the governor’s o ffice (California Legi slative Counsel, 2005).

### 4-7Table 4-3. Best Management Practices by StateBest Management PracticeADACTLAMANHNJNYORRIVTWARequirement/GuidanceGRRRRRRRRRRInitial UseUse only pre-capsulated alloys and/or stock a variety of capsule sizes.ΤΤΤΤΤΤΤDo not use bulk mercury.ΤΤΤΤΤRecycling/DisposalManage amalgam waste through recycling as much as possible.ΤΤΤΤΤΤΤΤΤRecycle used disposable amalgam capsules.ΤΤΤΤΤΤΤΤDo not flush amalgam waste down the drain or toilet.ΤΤΤΤΤΤΤΤΤΤSalvage, store and recycle non-contact amalgam (scrap amalgam).ΤΤΤΤΤΤΤΤΤΤΤSalvage amalgam pieces from restorations after removal (contact amalgam) and recycleamalgam waste.ΤΤΤΤΤΤΤΤΤΤRecycle teeth that contain amalgam restorations.ΤΤΤΤΤΤΤDo not put used disposable amalgam capsules in biohazard containers, infectious wastecontainers (red bags) or regular garbage.ΤΤΤΤΤΤΤΤΤΤDo not put non-contact amalgam waste in biohazard containers, infectious waste containers(red bags) or regular garbage.ΤΤΤΤΤΤΤΤΤΤΤDo not put contact amalgam waste in biohazard containers, infectious waste containers (redbags) or regular garbage.ΤΤΤΤΤΤΤΤΤΤDo not dispose of extracted teeth that contain amalgam restorations in biohazard containers,infectious waste containers (red bags), sharps containers or regular garbage.ΤΤΤΤΤΤΤΤChair-Side TrapsUse chair-side traps to retainamalgam and recycle the content.ΤΤΤΤΤΤΤΤΤΤDo not rinse chair-side traps containing amalgam over drains or sinks.ΤΤΤΤΤΤΤΤΤΤΤWhere appropriate, disposable amalgam traps are preferable to reusable traps.ΤΤΤΤΤ

### 4-8Table 4-3. Best Management Practices by StateBest Management PracticeADA CTLAMANHNJNYORRIVTWARequirement/GuidanceGR R R R R R R R R RVacuum PumpsRecycle contents retained by the vacuum pump filter or other amalgam collection device, ifΤΤΤΤΤΤΤΤΤΤthey contain amalgam.Do not rinse vacuum pump filters containing amalgam or other amalgam collection devicesΤΤΤΤΤΤΤΤΤΤΤover drains or sinks.Use line cleaners that minimize the dissolution of amalgam.ΤΤΤΤΤΤDo not use bleach or chlorine-containing cleaners to flush wastewater lines.ΤΤΤΤΤΤΤΤAmalgam SeparatorsInstall and use amalgam separators.ΤΤΤΤΤΤΤΤΤΤΤOtherAny dental practice using mercury should maintain a mercury spill kit on site and train allΤΤΤΤΤstaff on mercury spill cleanup response procedure.Do not disinfect teeth or any item that contains amalgam using heat.ΤΤΤΤSources: ADA, 2007a; CTDEP, 2006; MassDEP, 2007; NHDES, 2002; NJR,2007; NYDEC, 2007; RIDEM, 2007; VTDEC, 2006; and Lamperti, 2007.G — Guidance.R — Requirement.

### 4-9 4.2.2 State Dental Amalgam Guidance

EPA has reviewed guidance from five states that provide voluntary guidelines and BMPs to dental offices: Florida, Idaho, Minnesota, Washington, and the Di strict of Columbia. Table 4-4 summarizes the state BMPs and compares them to ADA’s BMPs.

4.3 Local Dental Amalgam Requirements and Guidance

This subsection summarizes mandatory and voluntary local programs for minimizing the discharge of dental mercury to wastewater. In addition, this subs ection attempts to evaluate the effectives of local voluntary programs. EPA notes this subsec tion is not intended to be an exhaustive list of local programs.

4.3.1 Local Dental Amalgam Requirements

EPA identified and reviewed mandatory program requirements for the following 9

localities:

• 

### King County Wastewater Treatm ent Division (KCWTD), WA;

• 

### East Bay Municipal Utility Di strict (EBMUD), Oakland, CA;

• 

### Palo Alto Regional Water Qualit y Control Plant (RWQCP), CA;

• 

### Northeast Ohio Regional Sewer Di strict (NEORSD), Cleveland, OH;

• 

### Several Wisconsin sewerage districts: Madison, Milwaukee, Neenah-Menasha, Oshkosh, GrandChute and Menasha West, Wausau, Fond du Lac and Green BayDe Pere, Waukesha, Watertown, Beloit, and La Crosse (Behm, 2008);

• 

### Fort Collins and Boulder, CO;

• 

### San Francisco, CA;

• 

### Solon, OH; and

• 

### Narragansett Bay, RI.

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

described in Section 4.2.1

. Table 4-5 summarizes the elements of the local requirements to control discharges of dental mercury. Table 4-6 compares the lists of local BMPs to ADA’s

BMPs.

### 4-10Table 4-4. Voluntary BMPs by StateBest Management PracticeADADCFLIDMNWAaInitial UseUse only pre-capsulated alloys and/or stock a variety of capsule sizes.ΤΤΤΤDo not use bulk mercury.ΤΤΤΤRecycling/DisposalManage amalgam waste through recycling as much as possible.ΤΤΤΤΤRecycle used disposable amalgam capsules.ΤΤΤΤDo not flush amalgam waste down the drain or toilet.ΤΤΤΤΤSalvage, store, and recycle non-contact amalgam (scrap amalgam).ΤΤΤΤΤSalvage amalgam pieces from restorations after removal (contact amalgam) and recycle amalgam waste.ΤΤΤΤΤRecycle teeth that contain amalgam restorations.ΤΤΤΤDo not put used disposable amalgam capsules in biohazard containers, infectious waste containers (red bags), or regulargarbage.ΤΤΤΤΤDo not put non-contact amalgam waste in biohazard containers, infectious waste containers (red bags), or regulargarbage.ΤΤΤΤΤDo not put contact amalgam waste in biohazard containers, infectious waste containers (red bags), or regular garbage.ΤΤΤΤDo not dispose of extracted teeth thatcontain amalgam restorationsin biohazard containers, infectious waste containers(red bags), sharps containers, or regular garbage.ΤΤΤChair-Side TrapsUse chair-side traps to retainamalgam and recycle the content.ΤΤΤΤΤΤDo not rinse chair-side traps containing amalgam over drains or sinks.ΤΤΤΤΤΤWhere appropriate, disposable amalgam traps are preferable to reusable traps.ΤΤVacuum PumpsRecycle contents retained by the vacuum pump filter orother amalgam collection device, if they contain amalgam.ΤΤΤΤΤDo not rinse vacuum pump filters containing amalgam or other amalgam collection devices over drains or sinks.ΤΤΤΤΤUse line cleaners that minimize the dissolution of amalgam.ΤΤΤDo not use bleach or chlorine-containing cleaners to flush wastewater lines.ΤΤAmalgam SeparatorsInstall and use amalgam separators.ΤΤΤΤ

### 4-11Table 4-4. Voluntary BMPs by StateBest Management PracticeADADCFLIDMNWAaOtherAnydental practice usingmercury shouldmaintaina mercury spill kit onsite and train all staffonmercury spillcleanupresponseprocedure.ΤΤDonotdisinfectteeth oranyitemthatcontains amalgamusingheat.ΤSources: ADA, 2007a; FLDEP, 2001; ISDA, 2008; MDA, 2003; WA Department of Ecology, 2006.a — According to sources at Quicksilver Caucus, the Washington program is currently a mandatory program. It is also listed in Section4.2.1of this report.

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

Element Examples from Local Requirements

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

installed.

• Install amalgam separators (East Bay, Palo Alto, Wisconsin, Fort Collins, San Francisco, Solon, Narragansett Bay).

• Alternative to installing an amalgam separator:

− Facility must pay a fee of $1,770/yr and be subject to inspections and testing (East Bay).

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

Francisco).

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

Narragansett Bay).

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

• Certain specialty fields (King County).

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

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

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

• Provide certification of compliance with BMPs (East Bay, Palo Alto, NE Ohio, Madison, Milwaukee).

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

Compliance tracking • Enforcement protocol including notice of violation, compliance schedule, and penalties for noncompliance (King County).

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

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

### 4-13Table 4-6. Best Management Practices by MunicipalityMunicipalityBest Management PracticeADAEast Bay,Oakland,CAKingCounty,WAMilwaukee andMadison, WIaNarragansettBay, RINE Ohio,Cleveland,OHPaloAlto,CARequirement/GuidanceGRRRRRRInitial UseUse only pre-capsulated alloys and/or stock a variety of capsule sizes.ΤΤΤΤΤΤDo not use bulk mercury.ΤΤΤΤRecycling/DisposalManage amalgam waste by recycling as much as possible.ΤΤΤΤΤRecycle used disposable amalgam capsules.ΤΤΤΤDo not flush amalgam waste down the drain or toilet.ΤΤΤΤΤΤΤSalvage, store, and recycle non-contact amalgam (scrap amalgam).ΤΤΤΤΤΤΤSalvage amalgam pieces from restorations after removal (contactamalgam) and recycle amalgam waste.ΤΤΤΤΤΤΤRecycle extracted teeth thatcontain amalgam restorations.ΤΤΤDo not put used disposable amalgam capsules in biohazardcontainers, infectious waste containers (red bags), or regular garbage.ΤΤΤΤΤΤDo not put non-contact amalgamwaste in biohazard containers,infectious waste containers (red bags), or regular garbage.ΤΤΤΤΤΤDo not put contact amalgam waste in biohazard containers, infectiouswaste containers (red bags), or regular garbage.ΤΤΤΤΤΤΤDo not dispose of extracted teeth that contain amalgam restorations inbiohazard containers, infectious waste containers (red bags), sharpscontainers, or regular garbage.ΤΤΤΤChair-Side TrapsUse chair-side traps to retainamalgam and recycle the content.ΤΤΤΤΤΤΤDo not rinse chair-side traps containing amalgam over drains or sinks.ΤΤΤΤΤΤΤWhere appropriate, disposable amalgam traps are preferable toreusable traps.ΤΤ(G)Τ(G)

### 4-14Table 4-6. Best Management Practices by MunicipalityBest Management PracticeMunicipalityADAEast Bay,Oakland,CAKingCounty,WAMilwaukee andMadison, WIaNarragansettBay, RINE Ohio,Cleveland,OHPaloAlto,CARequirement/GuidanceGRRRRRRVacuum PumpsRecycle contents retained by the vacuum pump filter oramalgam collection device, ifthey contain amalgam.otherΤΤΤΤΤΤΤDo not rinse vacuum pump filters containing amalgam or otheramalgam collection devices over drains or sinks.ΤΤΤΤΤΤΤUse line cleaners that minimize the dissolution of amalgam.ΤΤΤΤ(G)ΤDo not use bleach or chlorine-containing cleaners tolines.flush wastewaterΤΤΤΤΤ(G)ΤOtherAny dental practice using mercury should maintain a mercury spill kiton site and train all staff on mercury spill cleanup response procedure.ΤΤΤΤInstall and use amalgamseparators.TTTTTTTSources: ADA, 2007a; EBMUD, 2005; KCWTD, 2007; NEORSD, 2007; Palo Alto, 2007; Uva, 2007; WDA, 2004.a — The Milwaukee and Madison programs reference BMPs developed by the Wisconsin Dental Association (WDA, 2004).G — Guidance.R — Requirement.

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

This section summarizes volunt ary local programs that provided information to EPA on the participation rates for their programs. All of the programs i nvolve outreach to dentists to educate them on BMPs and use of amalgam sepa rators. The level of interaction between the program partners and local dentists varies grea tly from program to program. Follow-up activities to verify participation include su rveys, visits to dental offices , and contacting amalgam separator

vendors and waste haulers for lists of customers. In some cases, the available information did not give EPA enough details to determine how the participation rates were verified. Table 4-7 summarizes the voluntary programs and presents the participation rates for the programs. This table also contains some state voluntary program participation rates fo r comparison purposes.

4.3.2.1 Examples of Voluntary Programs with High Participation Rates

This subsection describes case studies of three voluntary programs that achieved participation rates greater than 90 percent or ex ceeded their goals for participation rates. It includes both local and state programs.

The Duluth program attributed its success to the following:

• 

### High level of cooperation from local dental societies;

• 

### One-on-one interaction with dentists; and

• 

### Providing financial ince ntives to dentists.

Kansas and Massachusetts each took a two-pha se approach to their programs. Phase 1 encouraged early installation of amalgam separa tors. Both states’ programs included specific goals and deadlines for participation. The sec ond phase of the program implemented mandatory requirements for installation of amalgam separato rs at dental offices. Both states reported participation rates exceeding 50 percent for the voluntary phase. Based on the success of its voluntary program, Kansas decided not to implement mandatory requirements. Massachusetts decided to continue to implement mandatory requirements under phase 2; however, the state rewarded the dental offices that voluntarily installed amalgam separators during phase 1 by allowing them to operate amalgam separators at a lower efficiency than the separators required under phase 2.

Duluth, Minnesota

In 1992, the Western Lake Superior Sanitary District (“WLSSD,” i.e., Duluth) and the Northeast District Dental Society formed a public-p rivate partnership that taught dentists how to recycle amalgam waste, made presentations at lo cal dental society meetings, and prepared and distributed written materials. As an incentive, the WLSSD purchased and in stalled separators at 51 dental offices, but left the la rgest long-term cost (recycling the amalgam) to be paid by the dentists (Walsh, 2007). ADA attributed the success of the program to the leadership of the local dental society, peer-to-peer inte raction with area dentists (i ncluding explaining the need to properly manage amalgam waste to prevent mercury from entering the environment and demonstrating the proper methods for doing so), financial incentives to install amalgam separators, and a discount wa ste disposal option through WL SSD’s “Clean Shop” Program. Currently, all 52 of the dental offices have installed amalgam separators.

### 4-16Table 4-7. Summary of VoluntaryPrograms for Reducing Dental Amalgam Releases to WastewaterState (Jurisdiction)DateDescriptionParticipation RateVerification of ParticipationCalifornia(Palo Alto, SanFrancisco, andCentral ContraCosta)NoinformationVoluntary installation of amalgam separators andimplementation of BMPs.65%Survey conducted by sanitationdistricts in 2000.Kansas(City of Wichita)April 2000Developed a Mercury Code of Management Practices(CMP).Encouraged dentists to use technologies beyond chairside trap and vacuum filter (e.g. amalgam separator).Wichita planned to require mandatory installation ofamalgam separators if participation in the voluntaryprogram had been low, but found that a mandatoryrequirement was not necessary.98% (out of 200 offices)No information.Massachusetts(MA DentalSociety)2004Goals were to have 50% of dentists install amalgamseparators by January 2005, 90% participation by2006, and 100% participation by 2007.MA later implemented mandatory requirements foramalgam separators.April 2005 — 75%No information.Minnesota(MN DentalAssociation)2001Voluntary installation of amalgam separators85% of dentists have committedto installing separators.No information.Minnesota (City ofDuluth)2001-2003Sanitation district purchased and installed amalgamseparators in dental offices.Dentists are responsiblefor cost of recycling.The sanitation district and local dental society alsoprovided education on how to recycle amalgam waste,trained dental offices, prepared written materials, andmade presentations at dental society meetings.100%Sanitation district paid for andoversaw the installation of allamalgam separators.Minnesota(Minneapolis, St.Paul)2003Voluntary installation of amalgam separators.700 clinics participated in program.The voluntary program was accompanied by a threatof eventual regulation and an industrial permitrequirement.99% of the clinics eligible forthe program installed separatorsNo information.

### 4-17Table 4-7. Summary of VoluntaryPrograms for Reducing Dental Amalgam Releases to WastewaterState (Jurisdiction)DateDescriptionParticipation RateVerification of ParticipationMissouri(Springfield)2006University ofMissouri conducteda study todeterminewhether voluntaryBMPscouldsignificantlyreducemercurydischargesfromdentaloffices.Offered ahalf-daytrainingcourseonBMPs.Alsosentoutreachmaterials viamail tolocalmembers of the dental society.Collected wastewater samples todetermine mercuryreductions(seeSection5.2.2).254 members inthelocaldentalsociety.54(21%) localdentists attendedthe half-daytrainingsessiononBMPs.76(30%)dentistsindicatedthattheyhad implemented BMPsasa result ofoutreach.Veryfew dentists installedamalgamseparators.UMsentafollow-upsurveytothe254 membersofthe localdentalsociety.Oregon(City ofCorvallis)2003Voluntaryinstallation ofamalgamseparatorsandimplementation ofBMPs.Corvallis wasawardedEPA’s 2006National FirstPlace CleanWater Act RecognitionAwardforPretreatment ProgramExcellence.100%.Noinformation.Washington(WA DentalAssociation)August2003Voluntaryinstallation ofamalgamseparatorsandimplementationofother BMPs.80% and anticipates anadditional 16%Noinformation.Washington(Seattle andKingCounty)NoinformationSignificant outreachto dental officeson propermanagementofscrapamalgam, properuseofchairside trapand pumpfilter waste, andamalgamseparators.Participation rate was solow that KingCountydecided toimplementa mandatoryprogram.<50%managed scrapamalgamproperly.25% installedamalgamseparators.10%contractedwith wastehaulers.KingCounty:Madeunannounced visits to 212dentaloffices.Contactedseparatorvendors toobtainlistsofdentalofficecustomers.Contacted waste haulers andmailaway firms toobtain lists ofdentalofficecustomers.Wisconsin(Madison)1997Encourageduse ofamalgamseparatorsthroughoutreach todentists.Section4.2.1describesthe mandatoryprogramthatwill be implementedinDecember 2008.23of103 dentists inthe area(22%).Surveyedlocaldentists todetermine how manyclinics useand/orremoveamalgamandhowmanyhadinstalled amalgamseparators.Sources: AMSA, 2002; MassDEP, 2007; MU Extension,2007; Walsh, 2007; KCWTD, 2007; and MMSD, 2008.

### 4-18 Wichita, Kansas

In April 2000, the Wichita Department of Wa ter and Sewer initiated a Mercury Code of Management Practices (CMP) for Wichita, Kansas . The CMP requires dental offices in Wichita, Kansas, to be equipped with devices to reduce th e amount of amalgam discharged into the public

waste streams. Phase 1 was an effort to enco urage voluntary use of technologies beyond the chair-side trap and vacuum filter, e.g., a separator. Phase 2 of the program would have required mandatory separators if the voluntary effort was not successful. Phase 2 of the program was never implemented because 60 percent of dental community complied voluntarily. According to ADA, 98 percent of the 200 dental offices in th e city complied with the Mercury CMP Program without a mandatory separator requirement (Walsh, 2007).

Massachusetts

In 2004, the Massachusetts Department of Environmental Protecti on (MassDEP) worked with the Massachusetts Dental Society to establ ish a voluntary program for dentists to install amalgam separators. The program used a two-phase approach:

• 

### First, MassDEP implemented a voluntary program that encouraged dental offices to install and use amalgam separato rs. The program called for 50 percent participation by January 2005, 90 per cent by January 2006, and 100 percent by January 2007.

• 

### Second, MassDEP implemented mandatory requirements, described in Section

4.2.1 , for operating amalgam separators, recy cling amalgam waste, and certifying compliance.

The voluntary portion of the program reported a 75 percent participation rate for the first year, exceeding MassDEP’s goals. In April 2006, MassDEP promulgated regulations mandating that most dental facilities install separators. Dentis ts who had complied with the voluntary program were rewarded with an exemption from the regul ation (i.e. record keep ing and reporting) until 2007 or 2010, depending on how early the dentist co mplied. In addition, den tists who installed separators under the voluntary program were permitted to continue operating their separators at 95 percent efficiency. The regulation required al l newly installed of amalgam separators to operate at 98 percent efficiency (MassDEP, 2007).

4.3.2.2 Examples of Voluntary Programs with Low Participation Rates

This section describes case studies for two voluntary programs that had participation rates below 50 percent. These programs, similar to the programs with high participation rates,

conducted extensive outreach to lo cal dentists to educate the de ntists on BMPs and the use of amalgam separators. Despite this effort, one of the two program s discussed in this section decided to implement mandatory requirements fo r BMPs and amalgam separators due to the low level of participation in the voluntary program.

### 4-19 Seattle and King County

In 1995, the Seattle–King County Dental So ciety set up a standing committee to work with the King County government. These partners met several times a year and pursued a number of activities, including (EPA, 2004):

• 

### Developing a poster and a handbook for dentists;

• 

### Writing articles for a dental journal;

• 

### Mailing information to all members;

• 

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

• 

### Presenting a “Green Dentistry” sessi on at two Pacific Northwest Dental

Conferences.

Other efforts undertaken inde pendently by King County include:

• 

### Advertisements seeking to educate dentists;

• 

### Outreach to dental supply houses;

• 

### Outreach to vocational/technical pr ograms for dental assistants;

• 

### Cash rebates for purchase of am algam separators (up to $500);

• 

### Technical assistance visits to dental offices; and

• 

### Promotion of dentists as “EnviroStars.”

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

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

During the fall of 1999 and spring of 2000, Ki ng County evaluated its voluntary dental program by conducting random visits to 212 dental o ffices and collecting data on the disposal of amalgam scrap, trap amalgam, pump filter sl udge, and fixer. King County also contacted separator vendors to obtain lists of dental offices that had purchased and installed separators, and waste haulers and mail-away firms to obtain lists of dental offices with waste management

contracts.

King County’s evaluation showed that the six-year voluntary program achieved the following results (EPA, 2004):

• 

### Less than half of dentists in the King County service area properly managed scrap amalgam.

• 

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

waste.

• 

### Only 25 dental offices installed amal gam separators (2.5 percent of those estimated to place and/or remove amalgam).

• 

### About 10 percent of dental offices contra cted with waste haulers and/or mailaway firms.

### 4-20 • 

### Hundreds of pounds of mercury from dental amalgams were still being disposed of annually to garbage, “red bags,” sewers, and “unknown” places.

• 

### The costs for King County’s voluntary program totaled over $250,000. During 1995–2001, an estimated $4,500 was spent on advertisements, $24,000 on the production of a poster and handbook, $65,000 on equipment rebates, $63,500 on field visits, and $100,000 for staff time.

Due to the lack of immediate success of this voluntary program, King County began a mandatory program as of July 2003. The mandato ry regulations are described in Section 4.3.1 (KCWTD, 2007).

Springfield, Missouri

The Springfield program included extensive outreach to local de ntists and was very successful in getting dentists to follow volunt ary BMPs. However, the program was unsuccessful in getting dentists to install amalgam separa tors. The program staff concluded that amalgam separators were not installed because they are not required.

In 2006, the University of Missouri (MU Exte nsion) began a study to determine whether dental offices could signifi cantly reduce their mercury disc harges though voluntary BMPs. Springfield was selected for the pilot study based on interest and commitment of staff resources from the Springfield Public Works Department and the Greater Springfield Dental Society (GSDS) (MU Extension, 2007). The discussion of th is study presented in this section focuses on participation rates for the voluntary program. Effectiveness of BMPs on reducing mercury

concentrations at POTWs is discussed in Section 5.2

.

MU distributed a questionnair e to Springfield dentists in February 2006 to collect baseline data on amalgam use and management practices. The questionnaire was sent to 123

dentists and there were 48 res ponses (39 percent). MU then o ffered area dentists a half-day training course on BMPs for dental amalgam. Eighty dentists and dental office st aff representing 54 local dental offices attended the training. Pa rticipants received a DVD, a wall poster with BMPs, a brochure of other available resources, and other written ma terials including:

• 

### Dental mercury hygiene recommendations;

• 

### ADA Guidelines on Amalgam Accumulati ons in Dental Office Plumbing;

• 

### Summary of Recent Study of De ntal Amalgam in Wastewater;

• 

### The Missouri Department of Natural Re sources’ determination of status and options for various types of dental waste; and

• 

### A list of amalgam recyclers.

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

One year later, MU distributed a follow-up questionnaire to 254 members of the GSDS to measure any changes in management practices that resulted from MU’s education efforts. The response rate was 76 dental offices (30 percent). The comparison of responses on reported dental amalgam management practices before and after intervention showed that the BMP training and education efforts may have succeeded in changing some practices:

### 4-21 • 

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

• 

### Improper disposal of capsules in regula r waste decreased after the training and education, while the number of dentists re porting setting amalgam capsules aside for pickup by an amalgam recycler increased significantly.

• 

### The collection and recycling of scrap am algam increased significantly after BMP training while the imprope r disposal decreased.

• 

### The amount of amalgam scrap disposed of as medical waste after the BMP training increased slightly. This findi ng may indicate a need for additional

education for dental office staff and bette r labeling and instruction from medical waste management companies.

• 

### Use of chair-side traps increased from the year before; the practice of disposing of trap contents with regular waste decreased.

• 

### More of the dentists who use pump filters reported placing filter contents in a container with medical waste; also reported was a slight increase in placing filter contents in a container for pickup by an amalgam recycler. Fewer dentists reported that they place filter co ntents in regular office waste.

• 

### More dentists reported that they disi nfected extracted teeth with amalgam

restorations and set them asid e for an amalgam recycler.

• 

### More dentists reported using an amalgam recycler and that their recycler also picks up medical waste. However, the major ity of dentists reported that they were unable to recycle amalgam waste because they could not locate a recycler in their area, locate a recycler to pick up small qua ntities of dental amalgam waste, find a method for shipping waste, or afford recycling amalgam.

According to the results of the survey, the education efforts by MU were extremely successful in educating dentists on BMPs. Howe ver, the majority of the dentists in the Missouri/Springfield area did not use amalgam separators prior to outreach and did not install amalgam separators after MU conducted its outreac h. MU concluded that very few dentists use amalgam separators because they are not requir ed in Missouri or Springfield (MU Extension, 2007).

4.3.2.3 Summary

Participation rates in voluntary programs ar e highly variable, ranging from as high as 100 percent of dentists in a community to as low as around 20 percent. Several programs that experienced low participation ra tes conducted extensive outreach and had frequent interaction with dentists. Therefore, the le vel of participation does not nece ssarily correspond to the level of

outreach and education.

### 4-22 The highest participation percentages were seen for voluntary programs that included the threat of a mandatory second phase. Examples of the mandatory second phase requirements include more stringent require ments for reporting or the requirement for higher amalgam separator efficiency standards. To avoid the more stringent mandatory requirements, dental facilities usually opted to comply with the volun tary requirements. Often, the mandatory second phase of the program was not ultimately impl emented. Also, voluntary control programs that directly purchased amalgam separators for the dentists to install were very successful.

The level of interaction between the program partners and local dentists varies greatly from program to program. Follow-up activities to verify participation include conducting surveys, visiting dental offices, and contacting amalgam separator vendors and waste haulers for

lists of customers.

According to an evaluation conducted by NACWA in 2002, participation rates in voluntary programs are highly variable, ranging from 100 percent to as low as 38 percent. NACWA also noted that during the first year of implementation regulatory programs will have higher participation rates than voluntary programs. However, over time (five to 10 years), participation rates for well-implemented voluntary programs will be similar to participation rates for mandatory programs (AMSA, 2002).

4.4 Common Elements Found in State and Local Programs

This subsection attempts to summarize comm onalities of state and local dental mercury programs discussed earlier in this section. Thes e programs encourage the use of (1) BMPs at

dental facilities to reduce the amount of mercury waste generate d and (2) wastewater treatment technologies to capture and recycle the me rcury that is present in discharges.

Element 1 — Identify All Mercury Sources.

Several state and local programs attempt to characterize all sources of mercury in their influent. For example, East Bay implemented a pr ogram to sample wastewater at the POTW to establish baseline mercury concentrations in the influent, effluent, and biosolids. East Bay then used these data to calculate the percent cont ributions to the influent mercury load from

residential and industrial sour ces (EBMUD, 2007). Similarly, King County conducted a dental office waste stream characterization study to determine baseline mercury discharges (King County, 1991).

Table 4-8 lists potential non-dental mercur y sources in POTW influent.

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

Commercial Activities Residential Sources

Hospitals

Laboratories

Universities Secondary schools

Medical clinics

Vehicle service facilities

Industrial activities Human waste (amalgam) Human waste (dietary) Laundry graywater Household products Improper disposal of mercury thermometers Atmospheric deposition from coal-fired utilities Naturally occurring elemental mercury

Source: (EPA, 2005).



### Element 2 — Design the Program.

State and local programs deve lop criteria for participation, a list of BMPs for dental facilities, incentives for participa tion, and goals for the program.

The usual recommended criterion for includi ng dental facilities in a mercury reduction program is whether the dental office conducts any placement or removal of amalgam fillings. Some programs exclude dental facilities usi ng a de minimis amount of amalgam. The King County program exempts certain specialty fields and facilities that remove amalgam no more than three days per year (KCWTD, 2007).

The ISO standards for amalgam separato rs are generally employed (see Section 5.1.1 ). Requirements beyond the ISO standards require substantial effort. Programs in King County and Narragansett Bay have also contacted separator ma nufacturers and suppliers for their expertise in separator selection and the development of main tenance requirements for BMPs (Chaimberlain et al, 2005 and Uva, 2007).

During the design stage, state and local offi cials decide on the mechanism they would use to impose standards on the dental community. Th e size of the community has sometimes been a key factor for selecting the appropriate cont rol mechanism. Larger communities sometimes found that a more formal program was necessary ; smaller communities found that outreach and education was more manageable.

Some programs establish specific goals for th e level of participati on and a timeframe for implementing BMPs. For example, the Madis on, WI program set goals of 100 percent compliance with BMPs and installation of am algam separators by December 31, 2008 (MMSD, 2008).

To provide incentives for participation, so me programs issue awards recognizing positive

action and subsidies for installi ng separators or recycling. Award s and subsidies successfully maintain rapport and speed progress. Mandatory programs also have required reporting and generally include penalties fo r facilities that do not comply with the requirements.

Finally, some programs have investigated opportunities to coordi nate their amalgam work with other environmental or health progr ams. For example, amalgam management can be consolidated with work regardi ng lead foil, X-ray film developm ent chemicals, radiation safety,

### 4-24 or medical waste (UW, 2008). The East Bay program included measures to control mercury from

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

Element 3 — Outreach and Education

A crucial element of any state or local program examined was effective outreach and education. Some examples are:

• 

### Identifying all dental facilities, using sources such as: local dental society membership lists, yellow pages, state licenses, and occupancy permits (UW, 2008).

• 

### Issuing a survey or visiting conducting site vi sits to local dental offices to identify current practices (program baseline) and to increase awareness of the program. Prior to implementing its program, Palo Alto visited 43 percent of dental facilities in its service area and determined baseline BMP and amalgam separator use (Palo Alto, 2007).

• 

### Speaking to the local dental societies to introduce them to the program and to identify any work that has already been done to reduce mercury discharges. East Bay and Madison worked with their local de ntal societies to de velop their dental programs (EBMUD, 2007 and MMSD, 2008).

• 

### Speaking to dental and techni cal schools about the program.

• 

### Maintaining a central database during th e implementation of the program to track the program’s progress and document ot her changes to the local dentist population. The Madison Municipal Sewe r District developed an in-house database to track to track the mercury program. The database is designed to manage contact data, facility identification and practices, survey data, and report generation (MMSD, 2008).

Element 4 – Monitor Reductions/Measure Program Success

For voluntary programs: One method for meas uring the success of a voluntary program is looking at participatio n rates. To do this local programs ha ve surveyed participants at local dental society meetings and maile d out surveys to measure participation rates. The University of Missouri (MU) conducted a study to evaluate the effectivenes s of a voluntary program in Springfield, MO. MU issued a survey to dental society members to measure changes in BMP use among dentists in the area. This also had the added benefit of increasing awareness of the voluntary program (MU Extension, 2007).

For mandatory programs: Mandatory program s usually have more formal reporting and monitoring to ensure that requireme nts are being met. The following is a list of methods used by mandatory programs:

### 4-25 • 

### Reporting wastewater monitoring, certif ication, and/or reporting. Dentists discharging to King County’s wastewater treatment division who elect not to install amalgam separators must demons trate compliance with a 0.2 ppm mercury limit (KCWTD, 2007).

• 

### Reporting the dates, locations, and amount of mercury waste recycled.

• 

### Monitoring POTW influent/effluent/biosolid s. East Bay monitors and analyzes mercury levels in its influent to m easure the effectiven ess of its program (EBMUD, 2007). King County uses biosolids monitoring data as an indicator of mercury levels in its treatme nt system (King County, 2008).

• 

### Conducting inspections of dental o ffices. King County conducts surprise inspections at dental facilities in its servic e area (KCWTD, 2007).

• 

### Requiring demonstration of amalgam sepa rator installation. Ea st Bay requires dentists to self certify installation of amalgam separators (EBMUD, 2007).

• 

### Requiring demonstration/certific ation of adherence to other BMPs. East Bay also requires dentists to self certif y adherence to BMPs (EBMUD, 2007).

• 

### Collecting customer information fr om amalgam separator vendors (many manufacturers keep track for maintena nce, parts replacement, and mercury recycling programs offered to their cu stomers). King County contact amalgam separator vendors to obtain customer lists to evaluate participation rates for its voluntary program (KCWTD, 2007).

Table 4-9 presents more specific examples of how mandatory programs have monitored compliance in state and local mercury control programs.

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

Element Examples from State Programs Examples from Local Programs

Submit separator certification to state environmental agency (CT, MA, ME, NJ). Provide certification for separator (East Bay, Palo Alto, Madison, Milwaukee).

Provide certification of compliance with BMPs (CT, MA, NH, NJ). Provide certification of compliance with BMPs (East Bay, Palo Alto, NE Ohio, Madison, Milwaukee).

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

Provide written notice of method of disposing of mercury removed by the separator (ME). Provide documentation of mercury waste hauling (East Bay, Palo Alto, NE Ohio).

DEP inspections (CT). Enforcemen t protocol including notice of violation, compliance schedule, and penalties for noncompliance (King County). Compliance tracking

Web form for providing proof of compliance (RI). Inspections performed by local POTW (East Bay, Palo Alto, Madison, Milwaukee).

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

### 4-26 Finally, according to NACWA

, sampling will be needed on a regular basis over a longer period of time to provide necessary trend inform ation. This is because mercury concentrations will likely decrease slowly. For example, sewer cleaning may affect mercury concentrations, and there may be mercury deposits accumulated in the dental facility piping (NACWA, 2007a). Tracking the change in mercury concentration in the influent, effluent, and biosolids have been used to monitor mercury reductions and evaluate program success. East Bay determined that mercury levels in its influent decreased 78 percent from 1998 to 2006 and 96 percent of permitted dental facilities have installed separators (EBMUD, 2007). King County’s biosolids data showed a 50 percent decrease in mercury from 2000 to 2006 (King County, 2008).

### 5-1 5. E FFECTIVENESS AND 

### C OSTS OF 

### D ENTAL 

### BMP S 

### , I NCLUDING 

### A MALGAM 

### S EPARATORS



### This section discusses the effectiveness and costs of reducing dental wastewater mercury discharges by implementing BMPs, including amalga m separators, at dental facilities. It also presents several case studies on influent and e ffluent POTW mercury concentrations following implementation of dental BMPs.

The remainder of this section is organized into the following subsections:

• 

### Section 5.1 discusses standards and treatment efficiencies for amalgam separators;

• 

### Section 5.2 presents case studies designed to demonstrate the impact of BMPs, including amalgam separators, on me rcury levels in wastewater; and

• 

### Section 5.3 discusses co sts of dental BMPs.

5.1 Treatment Efficiencies and St andards for Amalgam Separators

All BMPs, including chair-side traps and vacuum filters, can reduce amalgam discharges. The use of amalgam separators as a BMP is in tended to further reduce amalgam discharges. The configuration, office size, and operation of the dental office can significantly affect the choice of separator. The choice can also be affected by the operation and ma intenance requirements of the selected amalgam separator. The following sect ion describes standards for amalgam separators and separator treatment efficiencies.

5.1.1 Standards for Amalgam Separators

Two standards are used to evaluate treat ment efficiencies of amalgam separators:

• 

### The International Organization for St andardization (ISO) Standard 11143 and

• 

### The U.S. Environmental Protection Ag ency’s Environmental Technologies Verification (ETV) program.

ISO Standard 11143

The standard by which separators are most commonly evaluated is ISO Standard 11143 for Amalgam Separators. This standard requires that an amalgam separator remove at least 95 percent of amalgam particles by weight when subj ected to a specific test method as specified in the Standard. The ISO test for removal efficiency uses 10.00 grams of amalgam particles that are composed of three portions of different sizes (ISO, 1999):

• 

### 60 percent of the particles are 3.15 millimeters or smalle r and larger than 0.5 mm;

• 

### 10 percent of the particles are 0.5 mm or smaller and larger than 0.1 mm; and

• 

### 30 percent of the particles are 0.1 mm or smaller.

It is important to note that certification under this Standard is based not on total mercury

concentration in effluent wastew ater, but on particle removal. To test the efficiency of an amalgam separator, a slurry of water and amal gam is poured into the amalgam separator and

effluent water is collected. This effluent wastewater is filtered through a seri es of pre-weighted filters, the filters are dried and weighed, and the final weight of the filters is then compared

### 5-2 against the original weight (Batchu et al., 2006). By this method, an ISO Standard 11143– compliant amalgam separator will remove at leas t 95 percent, or 9.5 grams, of amalgam particles during laboratory testing.

EPA/ETV Standard

The EPA/ETV program has developed a st andard more rigorous than ISO 11143. The EPA/ETV standard, “Protocol for the Verificatio n of Hg Amalgam Removal Technologies,” uses

a concentration-based criterion a nd measures efficiency as a f unction of mercury concentration as opposed to particulate removal (NSF, 2001). EP A/ETV protocol recommends using Standard Methods 3500-Hg for sample collection, preserva tion, analysis, and storage. Standard Methods 3500-Hg, is a cold vapor atomic absorption method for determining the concentration on mercury in potable water (APHA, 1998). The EPA/ETV standard protocol is not used nearly as widely as the ISO Standard likely due to a la rger cost and time required for analyzing samples for the mercury content. See: http://www.epa.gov/etv/pubs/04_vp_mercury.pdf

5.1.2 Treatment Efficiencies

Studies have demonstrated the ability of amalgam separators to significantly reduce the amount of mercury amalgam in dental office wastewater.

• 

### A 1998 study tested three commercially avai lable amalgam separators that used different separation technol ogies including gravity sett ling, settling/filtration, and mechanical centrifuge. The mercury re moval efficiencies for the three technologies ranged from 95 to 99.9 percent. However, the study also noted that an effluent concentration of 0.2 parts pe r million could not be consistently met

without chemical treatmen t (Boston University, 1998).

• 

### A 2001 study found that amalgam separators were able to remove 91 to 99 percent of amalgam particles, with an average removal efficiency of 95 percent (MCES, 2001).

• 

### EPA Region 8 has reported that a properly installed amalgam separator will

achieve removal efficienci es ranging from 95 to 99.99 percent of particulate mercury (EPA, 2005).

In dental offices, amalgam separators are commonly used in conjunction with chair-side traps and vacuum pump filters. Most chair-side tr aps can filter particles as small as 0.7 mm and vacuum filter traps can capture particles as small as 0.4 mm, resulting in a combined removal rate of 40 to 80 percent of amalgam particles. Wh en chair-side traps and vacuum pump filters are used upstream of amalgam separators, the combin ed treatment system can achieve removal rates exceeding 99 percent (Fan et al., 2002).

Table 5-1 provides a non-inclusive li st of 28 commercially available amalgam separators, including manufacturer name, the type of par ticulate separation technologies used, and the amalgam removal efficiency based on IS O testing in a laboratory setting. 2 

### As illustrated, all

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

### 5-3 separators exceeded the ISO Standard of 95 pe rcent efficiency, 25 separators exceeded 97 percent efficiency, and 15 separators exceeded 99 percent efficiency of amalgam particle removal. The separators described in Table 5-1 achieved an average efficiency of 98.94 percent and a median efficiency of 98.7 percent.

Table 5-1. Effectiveness of Amalgam Separators

Model Manufacturer Treatment Technology Percentage of Amal g am Removal Efficiency d

A 1000 b Air Techniques Sedimentation 96.22% c

A 1300 a Air Techniques Sedimentation 99.27%

Amalgam Boss a Hygenitek Sedimentation, filtration, ion exchange 99.17%

Amalgam Collector a R & D Services Sedimentation 99.40%

ARU-10 e Hygenitek Sedimentation, filtration, ion Exchange 99.99%

Asdex b Avprox Filtration 99.23% c

Avprox AS-9 e American Dental

Accessories Sedimentation, filtration 95%–99%

BullfroHg b DRNA Dental Recycling Sedimentation, filtration 99.13% c

BullfroHg e Dental Recycling North

America Sedimentation 98.3%–99.6%

Durr 7800/7801 b Air Techniques Centrifugation 97.86% c

ECO II a Pure Water Development Sedimentation 97.05%

Guardian Amalgam

Collector e Air Techniques Sedimentation >95%

Hg Separator e SolmeteX Sedimentation, filtration, ion exchange >98%

Hg5 a SolmeteX Sedimentation, filtration, ion exchange 98.53%

Hg5 with Effluent Flow

Restrictor a SolmeteX Sedimentation, filtration, ion exchange 98.03%

Hg5 HV a SolmeteX Sedimentation, filtration, ion exchange 98.88%

Hg10 b SolmeteX Sedimentation, filtration, ion exchange 99.99% c

Merc II a Bio-Sym Medical Sedimentation, filtration, ion exchange 98.06%

MRU b DRNA Dental Recycling Sedimentation, filtration, ion exchange 99.96% c

MRU 10c a DRNA/ADA Technologies Sedimentation, filtration, ion exchange 99.97%

MSS 1000 a Maximum Separation Systems Sedimentation, filtration 99.54%

MSS 2000 b Maximum Separation Systems Sedimentation, filtration 99.3% c

Purevac Hg a Sultan Healthcare Sedimentation 99.91%

### 5-4 Table 5-1. Effectiveness of Amalg am Separators

Mo del Ma nuf ac turer Treatme nt Te chnol o g y Percentage of Amal g am Rem o val Efficiency d

Rasch 8 90- 1000 a AB Den t al Tren d s Sed i m en t atio n
, filtratio n, ion

excha n ge 98 .9 4% c

Rasch 8 90- 4000 b AB Den t al Tren d s Sed i m en t atio n
, filtratio n, ion

excha n ge 99 .9 2% c

Rasch 8 90- 6000 a AB Den t al Tren d s Sed i m en t atio n
, filtratio n, ion

excha n ge 98 .3 1% c

REB e R e bec Si m p l e Sol u t i o ns Sedi m e nt at i on 96 .9 0%

RME 20 00 b R e bec Sedi m e nt at i on 99 .6 7% c

Aver age 98 .7%

a — Results according to Batchu et al., 2006. b — Results according to Fan et al., 2002. c — Percentage of amalgam removal efficiency is calculate d as the average of mean efficiency of empty separator and mean efficiency of full separator. d — This efficiency is based on the percentage of mercury in the form of dental amalgam removed by weight, as

instructed in ISO Standard 11143. e — Results according to McManus and Fan, 2003.



### As listed in Table 5-1 , sedimentation, either alone or in conjunction with filtration and/or ion exchange, is used in the majority of am algam separators. The hi gh specific gravity of amalgam causes it to settle read ily from suspension in water which allows the dental wastewater to be effectively treated by se dimentation (Fan et al., 2002). Although none of the separators

listed in Table 5-1 used added chemicals, chemical and polymer additions can enhance

sedimentation treatment and have demonstrated effectiveness in precipitating at least some portion of dissolved mercury out of dental wastewater. Some amalgam separator systems incorporate ion-exchange to remove dissolved mercury.

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

This subsection summarizes case studies de monstrating the impact of BMPs, including amalgam separators, on dental mercury discharg es to POTWs. Most case studies show a decrease in the amount of mercury discharged to POTWs following installation of amalgam separators in dental offices. However, it is di fficult to predict with any certainty the impact on POTW influent of the use of amalgam separato rs due, in part, to other mercury sources at POTWs. Also, other dental BMPS implemented at the same time as amalgam separators reduce mercury discharges to POTWs.

5.2.1 Summary of Dental BMPs

Most state and local BMPs for dental facilities are base d on the ADA BMPs developed in 2003. Additionally, some municipalities require de ntal facilities to implement BMPs, while others have introduced voluntary BMP programs. Section 4 describes mandatory and voluntary

programs.

To manage and recycle dental amalgam waste, ADA BMPs (ADA, 2007a) include the following:

### 5-5 • 

### Using precapsulated alloys and st ocking a variety of capsule sizes;

• 

### Recycling used disposable amalgam capsules;

• 

### Salvaging, storing and recy cling non-contact amalgam;

• 

### Salvaging (contact) amalgam pieces from rest orations after rem oval and recycling the amalgam waste;

• 

### Using chair-side traps, vacuum pump filte rs and amalgam separators to retain amalgam and recycle their contents;

• 

### Recycling teeth that cont ain amalgam restorations;

• 

### Managing amalgam waste through recyc ling as much as possible; and

• 

### Not using bleach or chlorine-containing cleaners to flush wastewater lines.

Using bleach or chlorine-c ontaining cleaners can mobilize mercury from amalgam that has settled in plumbing fixtures and potentially cause the dissol ution of mercury from amalgam waste (EPA, 2003 and Batchu et al, 2006a). Also , some BMPs encourage dentists to use approved suction line cleaners in stead of oxidizing cleaners. So me BMPs recommend avoiding

the use of heat to disinfect teeth or other items that contain amalgam to minimize air releases of

mercury.

5.2.2 Summary of Case Studies

Table 5-2 summarizes dental BMP effectivenes s on mercury discharged to POTWs, based on several studies. The City of Corvallis, OR, believes that the implementation of BMPs is highly effective in reducing the daily mass load of mercury in the influent to the Corvallis Wastewater Reclamation Plant (Lamperti, 2007) . However, a study conducted by the National Association of Clean Water Agencies (NACWA ) from 2003 to 2006 concluded that influent mercury loads at POTWs were highly variable. As a result, it was difficult to collect a representative sample. Although reductions were observed for so me of the POTWs included in the study, NACWA concluded that the ability of POTW influent mercury loads to measure the impact of mercury control technologies at dental offices is li mited (NACWA, 2007a).

5.2.3 Considerations for Determining Impacts of BMPs on POTW Influent Mercury

Levels

Although most of these studies show mercury reductions in POTW influent following the introduction of BMPs in dental offices, so me studies show an increase in mercury concentrations. Thus, it is apparent that othe r factors can influence mercury levels and the measure of BMP effectiveness. As a result, there is uncertainty about the effectiveness of BMPs at reducing mercury at POTWs. Therefore, a PO TW cannot predict with certainty that amalgam separators will decrease mercury concentrations in the influent wastewater without also exploring the other po tential contributors (NACWA, 2007b) . The following are examples of

additional criteria that affected the mercur y levels in the NACWA 2007 case studies.

• 

### Many programs are voluntary, making BMP part icipation rates hard to determine.

• 

### Dental offices are not the only source of mercury to POTWs. The next largest sources are domestic sources (human waste, household products, and laundry graywater) and hospitals (AMSA, 2002).

### 5-6Table 5-2. Impact of BMPs on Mercury Discharged to POTWPercent of Dentists Using AmalgamSeparatorsBMP ProgramDescriptionBefore ProgramAfter ProgramPercent Mercury LoadReductionSourceCalifornia DentalAssociationVoluntary installation of amalgamseparators.No informationNo information78% of amalgam to POTWCondrin. 2004Corvallis, ORVoluntary installation of amalgamseparators.No informationNo information79% of POTW influentLamperti, 2007Springfield, MOBMP outreach program.No informationNo information34% of POTW influent AaMU Extension,2007Springfield, MOBMP outreach programNo informationNo information96% of POTW Influent BbMU Extension,2007Madison, WIVoluntary installation of amalgamseparators.No information22% (as of 2005)No trend in POTW influentWalsh, 2007EBMUDRequired installation of amalgamseparators.No information96%No trend in POTW influentWalsh, 2007Wichita, KSVoluntary installation of amalgamseparators.60%99%No trend in POTW influentWalsh, 2007Milwaukee, WIRequired installation of amalgamseparators.No informationNo informationDecrease in POTW influentWalsh, 2007Duluth, MNSt. Louis River Beneficiary Groupprovided a grant to purchase amalgamseparators for all offices.No information100%Decreasein POTW sludgeWalsh, 2007Palo Alto, CARequired installation of amalgamseparators.No information96%No trend in POTW influentWalsh, 2007Narragansett Bay,RIVoluntary installation of amalgamseparators.No informationNo informationNo trend in POTW influentWalsh, 2007MCES —MetropolitanWastewaterTreatment PlantVoluntary installation of amalgamseparators.No informationNo information50.6% of POTW influentNelson, 2007MCES —HastingsWastewaterTreatment PlantCommunity-wide study. MCESestablished a baseline, installed theamalgam separators at dental offices,conducted sampling, and then removedthe amalgam separators.0%100%(6 facilities total)44% of POTW influentNelson, 2007

### 5-7Table 5-2. Impact of BMPs on Mercury Discharged to POTWPercent of Dentists Using AmalgamSeparatorsPercent Mercury LoadBMP ProgramDescriptionReductionSourceBefore ProgramAfter ProgramMCES — CottageCommunity-wide study. MCES0% 87.5%29% of POTW influent Nelson, 2007Grove Wastewaterestablished a baseline, installed the(7 out of 8 facilities)Treatment Plantamalgam separators at dental offices,conducted sampling, and then removedthe amalgam separators.King County, WA Voluntary installation of amalgamNo information 95%50% of POTW biosolidsKing County,separators and mandatory(concentration-basis)2008implementation of BMPs.POTW “A” Required facilities to either install0%100%No trend in POTW influent NACWA, 2007aamalgam separators or demonstratecompliance with a mercury limit of0.005 ppm.POTW “B” Mandatory BMP program began in5%9% (out of 21956.4% of POTW influent NACWA, 2007a2002. Installation of amalgam separatorsfacilities)was not required.POTW “C” BMP program began in 2002. Some6%6% (out of 1843% of POTW influent NACWA, 2007aBMPs were mandatory. Installation offacilities)amalgam separators was voluntary.POTWs “D” andProgram required implementation of0.6%38% (total number of 60.5% of influent to POTWNACWA, 2007a“E”BMPs by 2004 and installation offacilities unknown)“D”;amalgam separators by 2008.22.0% of influent to POTW “E”POTW “F” Voluntary amalgam separator program0%20% (total number of38.0% of POTW influent NACWA, 2007abegan in 1997.facilities unknown)POTW “G” Voluntary installation of amalgam44% 100%(100facilities90% increase to POTW influent NACWA, 2007aseparators.total)POTW “H” Voluntary amalgam separator program60%98% (out of ~200No trend in POTW influent NACWA, 2007abegan in 2002.facilities)POTW “I” Mandatory amalgam separator program94%98% (total number of27.5% of POTW influent NACWA, 2007abegan in 2001.facilities unknown)POTWs “J” andMandatory program required dentists to94%98% (total number of8.9% increase to POTW “J”;NACWA, 2007a“K”meet a limit of 0.2 mg/L by July 2003.facilities unknown)44.1% reduction to POTW “K”

### 5-8Table 5-2. Impact of BMPs on Mercury Discharged to POTWBMP ProgramDescriptionPercent of Dentists Using AmalgamSeparatorsPercent Mercury LoadReductionSourceBefore ProgramAfter ProgramPOTW “L”POTW recommends installation ofNo information11% (total number of50.6% of POTW influentNACWA, 2007aamalgam separators to dentists.facilities unknown)a — Northwest Treatment Plant.b — Southwest Treatment Plant.

### 5-9 • 

### The time required to flush accumulated am algam particles from the collection system is not known.

• 

### The time needed for mercury reductions at POTWs to be measurable after BMPs are implemented is not known.

5.3 Costs of Dental BMPs

The cost of a BMP program includes costs to state and local agencies to implement the program and costs to individual dent al facilities to participate. Th e costs to local agencies include development of the program and costs for outreach to dentists. Depending on the program, the costs to individual dental offices will ge nerally encompass purchasing, installing, and maintaining an amalgam separator; recycling the collected amalgam; and other costs, such as time spent educating their employees. The Califor nia Dental Association indicates that “the numerical cost of BMP implementation is low” (Condrin, 2004), and according to Bates, BMPs would cost approximately $300 per facility per y ear if implemented in New Jersey (Bates, 2006).

5.3.1 BMP Program Costs to State and Local Agencies

Table 5-3 shows the costs of several pollution pr evention program elements estimated by AMSA and the Oregon Association of Clean Wate r Agencies (ACWA). These cost estimates are based on the cost of pollution prevention programs and the cost to develop pollution prevention programs in the past. All the pollution pr evention/voluntary programs presented in Table 5-3 addressed only dentists.

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

Program Description Total Cost ($2008) Number of Participants Source

San Francisco, CA Brochure/fact sheets + distribution $80,600 900 AMSA, 2002

San Francisco, CA Site visits $16,100 35 visits AMSA, 2002

Palo Alto, CA Brochure/fact sheets + distribution $16,100 500 AMSA, 2002

Palo Alto, CA Outreach/advisory group $13,400 500 AMSA, 2002

Western Lake Superior District, MN Outreach $40,3 00 100 AMSA, 2002

Salem, OR Staff labor $8,330 109 ACWA, 2007

Salem, OR Inspection or other form of contact $4,880 109 ACWA, 2007

Oregon State All costs in 2004 $3,950 53 ACWA, 2007

Oregon State All costs in 2005 $1,420 26 ACWA, 2007

Oregon State All costs in 2006 $6,380 36 ACWA, 2007



### 5.3.2 Costs to Facilities

The major costs to dental offices fo r implementing mandatory or voluntary BMP programs are the costs to purchase and maintain an amalgam separator and the costs to collect and recycle amalgam waste. This subsection describes these costs.

### 5-10 Amalgam Separator Costs

Most BMP programs recommend, if not requir e, dental offices to install amalgam separators. Dentists have three optio ns for obtaining amalgam separators:

• 

### Purchase the unit and maintain it themselves;

• 

### Purchase the unit and contract a company to maintain it; or

• 

### Lease the unit, with maintenance service inclusive in the fee.

Amalgam separator life-cycle costs can include (PACE, 2007):

• 

### Purchase or lease cost;

• 

### Installation cost;

• 

### Additional equipment costs;

• 

### Maintenance costs;

• 

### Replacement cost;

• 

### Shipping costs; and

• 

### Recycling costs.

Manufacturer suggested reta il prices (MSRP) range fr om $215 to $7,450 (depending on the size of the dental office), and certain m odels can be installed and operated under lease arrangements for $39 to $100 per month. Table 5-4 provides a summary of costs of commercially available amalgam separator system s (non-inclusive), includ ing specific operating

and maintenance costs for each model in 2008 dollars. 3



### To verify the manufacturer estimates in Table 5-4

, Table 5-5 presents amalgam separator purchase, installation, operati on, and maintenance costs from information provided in other

studies.

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

### 5-11Table 5-4. Cost of Purchasing, Operating and Maintaining Amalgam Separators ($2008)aModelManufacturerMSRPMaintenanceReplacement PartsRecycling?First YearCostOtherYear CostsA1000Air Techniques$1,010Replace collectingcontainers every 6 monthsFilter: $672Notincluded$1,010$672A110Air Techniques$2,020Replace collectingcontainers every 6 monthsReplacement kit: $1,010Included$2,020$1,010A1200Air Techniques$2,020Replace collectingcontainers every 6 monthsReplacement kit: $1,010Included$2,020$1,010A1300Air Techniques$4,030Replace collectingcontainers every 6 monthsReplacement kit: $1,010Included$4,030$1,010A1400Air Techniques$4,340Replace collectingcontainers every 6 monthsReplacement kit: $1,010Included$4,340$1,010AmalgamCollectorR & D Services$470–$1,680Conduct weeklymaintenance and decanttreated wastewaterReplace unit every 9 to 12monthsSludge removal every 2 to5 yearsUnknownNotincluded$470–$1,680UnknownARU-10Hygenitek$671–$928Lease: $52/moReplace canister every 6monthsReplace sedimentation tankevery 6–24 monthsFilter canister: $133–$202Sedimentation tank: $79–$101Included$977–$1,380$306–$605Avprox AsdexAmericanDentalAccessories$289Replace canister every 4–6weeksCanister: $47Notincluded$697–$901$408–$612Avprox AS-9AmericanDentalAccessories$309Replace filter every 3–8monthsFilter: $106Notincluded$468–$734$159–$425BullfroHgDentalRecyclingNorth AmericaPurchase: $934Lease: $134/mo(2-year minimum)Replace separator annuallyUnknownIncluded in lease$605 / year$1,540$605Catch Hg 400SeriesRebec$1,320Annual recycling requiredAnnual recycling: $531Included$1,860$531

### 5-12Table 5-4. Cost of Purchasing, Operating and Maintaining Amalgam Separators ($2008)aFirst YearOtherModelManufacturerMSRPMaintenanceReplacement PartsRecycling?CostYear CostsCatch Hg 1000Rebec$2,550–$4,030 Annual recycling required Annual recycling: $531–Included $3,080–$4,690 $531–$665Series$665Durr SystemAir Techniques $5,380 Replace cassette once perCassette: $128Included $5,380 $1287800/7801yearECO II Pure WaterPurchase: $739Apply recommendedCleanser: $101Included $840 $101DevelopmentLease: $73/mocleanser dailyReplacements are includedReplace separator annuallyunder the leaseGuardianAir Techniques $2,020–$4,380 Replace collectionReplacement kit: $1010 Included $2,020–$4,380 $1,010Amalgamcontainer every 6 to 12CollectormonthsHg5 Solmtex $934Replace cartridge every 6Resin cartridge: $202–$370Not$1,240–$1,510 $605–(1–10 chairs)monthsFilter: $101–$202included$1,140Hg10 Solmtex $10,010Replace cartridge every 6Resin cartridge: $202–$370Not$10,300–$605–(>10 chairs)monthsFilter: $101–$202included$10,590$1,140Merc II Bio-Sym$1,200–$1,740 Replace unit annually Replacement unit installationIncluded $1,200–$1,740 $665Medicaland disposal: $665MSS ModelMaximum$1300–$1,880 Replace settling tankSettling tank: $222Not$1,300–$1,400 $5711000SeparationannuallyTank recycling: $249includedSystemsCleanser: $101MSS ModelMaximum$4,030 Replace settling tankSettling tank: $222Not$4,030 $5712000SeparationannuallyTank recycling: $249includedSystemsCleanser: $101REB 1000 Rebec Simple$2,550 Annual recycling required Replacement parts: $531 Included $2,550 $531SolutionsREB 5000 Rebec Simple$2,550 Annual recycling required Replacement parts: $531 Included $2,550 $531SolutionsREB 7000 Rebec Simple$2,550 Annual recycling required Replacement parts: $665 Included $2,550 $665SolutionsREB 9000 Rebec Simple$4,030 Annual recycling required Replacement parts: $531 Included $4,030 $531SolutionsRasch 890-AB Dental$1,600 Replace canister every 12–Canister: $801Included $1,600 $8011000Trends18 months

### 5-13Table 5-4. Cost of Purchasing, Operating and Maintaining Amalgam Separators ($2008)aModelManufacturerMSRPMaintenanceReplacement PartsRecycling?First YearCostOtherYear CostsRasch 890-4000AB DentalTrends$2,220Replace canister every 12–18 monthsCanister: $1,010Included$2,220$1,008Rasch 890-6000AB DentalTrends$895Replace canister every 12–18 monthsCanister: $801Included$895$801Average$2,320$2,550$657Table adapted from EBMUD, 2002 and 2004; McManus and Fan, 2003. Journal of the American Dental Association. Purchasing, Installing and OperatingDental Amalgam Separators. Volume 134, August 2003 (pp. 1054-1059).

### 5-14 Table 5-5. Estimated Purchase, Installati on, and O&M Costs of Amalgam Separator ($2008)

Purchase Cost Installation Cost O&M Cost

Source Low High Low High Low High

Metropolitan Council Environmental Services and the Minnesota Dental Association (MCES, 2001) $221 $4,840 $415 $691

Association of Metropolitan Sewerage Agencies (AMSA, 2002) $134 $4,030 $565 $3,230

King County (WA) Department of Natural Resources and Parks (King County, 2005) $171 $2,280 $228 $571 $228 $799

Palo Alto (CA) Regional Water Quality Control Plant (RWQCP), Amalgam Recovery Program (Palo Alto, 2007) $181 $2,410 $60 $1,204 $301 $722

Binational Toxics Strategy Mercury Workgroup, Great Lakes National Program Office, U.S. EPA (EPA, 2003) $393 $3,930 $262 $262

Vandeven and McGinnis a (Vandeven and McGinnis, 2004) $1,200 $2,410

Bates (Bates, 2006) $748 $1,070

U.S. EPA (EPA, 2003) $98 $983

Journal of the California Dental Association (Condrin, 2004) $361 $602

(Behm, 2008) $600 $1,500 $200 $600

Average b $283 $3,170 $188 $659 $388 $1,160

a — The range of prices includes both the cost of purchas e and installation.

b — Does not include Vandeven and McGinnis costs.



### A key component in amalgam separator inst allation costs is labor for plumbers, pipe fitters, and steamfitters. According to the 2006 O ccupational Employment and Wage survey and consistent with a MCES study, the mean hourly wa ge for plumbers, pipe fitters, and steamfitters is $22.03, not including benefits (BLS, 2006a). Ba sed on the studies described above and the average MSRP for separator models included in Table 5-4 ($1,580), a conservative estimate for the cost of purchasing and installing an amalgam separator is about $2,000. Table 5-7 below shows that the average MSRP and annual O&M costs provided by manufacturers in Table 5-4 that fall within the average high- and low-cost range determined in Table 5-5 from nine regional

studies.

Table 5-6. Summary of Cost Estimates

Type of Cost Cost ($2008)

Average cost of purchase ( Table 5-4 ) $2,320

Average cost of purchase range ( Table 5-5 ) $283–$3,170

Average annual cost of O&M ( Table 5-4 ) $657

Average annual cost of O&M range ( Table 5-5 ) $388–$1,160

### 5-15 Cost of amalgam separators can vary, but are relative to the size of the dental operation.

Table 5-7 lists prices based on information gathered by Partners for a Clean Environment (PACE) from manufacturers in September 2005. The number of amalgam separators to be installed depends on the number of chairs in an office and th e amalgam separator model. The wastewater flow rate determines how often filters and traps need to be cleaned/replaced (Walsh, 2007). The costs for small dental offices are clos e to itemized and annual costs estimated in

Tables 5-4 and 5-5.

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

Small (1–4 Chairs) Medium (5–12 Chairs) Large (+12 Chairs)

Purchase $228–$1,370 $760–$2,510 $2,850–$10,000

Installation $114–$228 $143–$297 $228–$1,140

Maintenance $0–$228 $0–$228 $0–$228

Replacement $57–$856 $86–$856 $ 571–$2,400

Estimated annual cost $211–$1,073 $293–$1,110 $1,990–$4,630

Source: Walsh, 2007.



### 5.3.3 Amalgam Recycling

For 11 of the 15 separators examined (see Table 5-4 ), costs included recycling services and the replacement of used amalgam canisters . This recycling service included either:

• 

### The recycler picking up amalgam waste at dental offices or

• 

### The recycler providing packaging mate rial, shipping labels and shipping manifests to the dentist so they can ship the collected amalgam to the recycler

Annual service and maintenance costs—including recycling—range from $95 to $750 per year. The ADA estimated a conservative (low) cost of using a recycling service to be $450 per year (Walsh, 2007). EPA estimates recycling costs ar e less than $600 per year (Singer, 2007b).

### 6-1 6. D ENTAL 

### M ERCURY 

### P ASS 

### -T HROUGH 

### A NALYSIS



### This section describes EPA’s analysis of the potential for dental mercury discharges to pass through POTWs. EPA determined the potential for pass-thr ough by comparing the percentage of mercury rem oved by well-operated POTWs ach ieving secondary treatment (“baseline discharges”) with the percentage of pollutant removed assuming100 percent participation in an amalgam separator progr am. EPA typically dete rmines pass-through by comparing the baseline discharges with the lim its for Best Available Technology Economically Achievable (BAT) for the category. EPA has not set national categorical regulations for the health services industry, howev er, so BAT limits do not exis t for comparison. The following subsections describe EPA’s assumptions and calculations for this analysis:

• 

### Section 6.1 presents the number of dentists using amalgam;

• 

### Section 6.2 presents calculations fo r mercury discharges from amalgam restorations and amalgam removals;

• 

### Section 6.3 summarizes the baseline mercury discharge to POTWs;

• 

### Section 6.4 presents estimates of potentia l reductions from the installation of amalgam separators;

• 

### Section 6.5 summarizes the annualized costs for amalgam separators; and

• 

### Section 6.6 summarizes the results for the assumed participation rates and

associated costs.

6.1 Number of Dentists

This subsection summarizes the data and assumptions that EPA used to estimate the number of dentists in the United States who pot entially install or remove amalgam restorations. A 2007 ADA survey reported a total of 163,181 activ e dentists in the United States in 2004 (ADA, 2007b). Although only a portion of these de ntists install amalga m restorations (e.g., a 2005 study by VanDeven and McGuiness estimates th at 75 percent of general dentists install amalgam restorations), all dent ists have the potential to remove old amalgam when installing new, non-mercury restorations. Therefore EPA assumed that all active general dentists and specialists who work in fields that use amalga m may remove old amalga m fillings. Similarly, it was assumed that all U.S. dental offices ( 122,918) would be subject to mandatory amalgam separator installation programs because all offices have the potential to discharge mercury from amalgam removals even if they do not install amalgam restorations.

Calculations that use assumptions based on the number of dentists or dental offices include the mass of mercury discharged from am algam removals and the number of facilities using chair-side traps, vacuum pump filters , and amalgam separators. The mass of mercury discharged from amalgam removals (see Table 6-3 ) is based on the total number of dentists . For this calculation, EPA used the estimated number of specialists in fields that use amalgam (11,353) and the number of general dentists (129,745) from Table 6-1 . To calculate the baseline use of chair-side traps, vacuum pump filters, and amalgam separators (see Table 6-4 ), EPA used assumptions based on the number of dental offices . For these calculations, EPA used the total

number of dental offices (122,918) from Table 6-1

.

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

Description Value Type Calculation Source/Notes

Total number of active dentists 162,181 Data None ADA, 2007b

Number of general dentists 129,745 Estimation 80% of total dentists ADA, 2007b

Number of specialists 32,436 Estimation 20% of total dentists ADA, 2007b

Number of specialists in fields that use amalgam 11,353 Estimation 35% of specialists that work in fields that use amalgam Vandevin & McGuiness, 2005

Total number of dental facilities 122,918 Data None ADA, 2007b



### 6.2 Mercury Discharge from Amalgam Restorations and Amalgam Removal

This subsection summ arizes the calculations used to determine the tons of mercury discharged from amalgam restorations and amalgam removals. Table 6-2 shows detailed calculations used in this analysis to determine the total amount of mercur y discharged to POTWs from amalgam restorations.

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

Description Value Type Calculation Source

Number of total restorations performed in US in 1999 71,000,000 Data None Vandeven and McGinnis, 2005

Mercury content of amalgam capsule 450 mg Data None Vandeven and McGinnis, 2005

Amount of mercury used for

restoration 340 mg Data None Vandeven and McGinnis, 2005

Amount of mercury disposed of as non-contact scrap amalgam 110 mg Data None Vandeven and McGinnis, 2005

Amount of mercury used per restoration that is discharged

to wastewater 31 mg Estimation 9% of the amount of mercury used

for restorations Vandeven and McGinnis, 2005

Total amount of mercury discharged to wastewater

from restorations 2.40 tons Result Product of number of restorations performed (71, 000,000) and amount of mercury used per restoration that is discharged to wastewater (31 mg)



### Table 6-3 shows detailed calculations used to determine the total amount of mercury discharged to POTWs from amalgam removals.

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

Description Value Type Calculation Source

Total number of removals per general dentist per year 710 Data None Vandeven and McGinnis,

2005

Total number of removals per specialist per year 440 Data None Vandeven and McGinnis,

2005

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

Description Value Type Calculation Source

Total number of removals by general dentists 92,118,808 Estimation Product of removals by general dentists (710) and number of general dentists (129,745) See Table 6-1

Total number of removals by specialists 4,995,175 Estimation Product of removals by specialist (440) and number of specialists

who work in fields that use amalgam (11,353) See Table 6-1

Total number of removals 97,113,983 Estimation Sum the number of removals by performed by general dentists and specialists

Mercury content of amalgam

removed 300 mg Data None Vandeven and McGinnis,

2005 a

Amount of mercury per removal that is discharged to

wastewater 270 mg Assumption 90% of mercury content of amalgam removed Vandeven and McGinnis,

2005

Total amount of mercury discharges to wastewater from amalgam removals 27.4 tons Result Product of amount of mercury per removal that is discharged to wastewater (270 mg)

and total number of removals (97,113,983)

a — Accounts for decay and deteriora tion of amalgam filling over time.



### According to Tables 6-2 and 6-3, EPA estimates the total mercury mass present in

untreated dental wastewater due to both inst alling and removing amalgam restorations to be 31.3

tons . This is the mass prior to any removals from chair-side traps, vacuum filters, or amalgam

separators.

6.3 Determining Baseline Mercury Discharge to POTWs

This subsection summarizes the calculations used to determine the baseline mercury discharged to POTWs. The mercury discharge is calculated for each group of dental facilities using the same type of amalgam treatment sy stem. For estimation of baseline loads, EPA

assumed that some dental facilities alrea dy had treatment in place. EPA assumed that 100 percent of dental offices had chai r-side traps and that 80 percent of facilities also used vacuum filters. These assumptions are consistent with ADA’s analysis (Vandeven and McGinnis, 2005).

To estimate the number of dental facilities with amalgam separators installed, EPA used the following assumptions using 2005 census data for the number of dental facilities by state (presented in Table 6-8 located at the end of this section):

• 

### 100 percent of facilities in each state have the pote ntial to remove amalgam fillings from their patients.

### 6-4 • 

### If the state had a mandatory program that required the use of amalgam separators, then 100 percent of the dental offices used amalgam separators.

• 

### If the state had no program, then EPA assumed that 20 percent of the dental offices used amalgam separators. (EPA assumed 20 percent to account for dentists that might have installed an amalgam separator on their own and to account for local amalgam separator programs.)

Table 6-4 describes in detail the calculation used to determine the total baseline mercury discharged to POTWs.

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

Description Value Type Calculation Source

Number of facilities using only chair-side traps 24,584 Assumption 20% of all dental facilities use only chair-side traps Vandeven and McGinnis,

2005

Number of facilities using chair-side traps and vacuum pump filters 49,167 Assumption 40% of dental facilities use only chair-side traps and vacuum pump filters Vandeven and McGinnis,

2005

Number of facilities using chair-side traps, vacuum pump filters, and amalgam

separators 49,167 Assumption 40% of dental facilities use amalgam separators, vacuum pump filters, and chair-side

traps See Table 6-8

Removal efficiency of chairside trap 0.680 Data None Vandeven and McGinnis,

2005

Removal efficiency of chairside trap + vacuum pump

filter 0.810 Data None Vandeven and McGinnis,

2005

Removal efficiency of chairside trap, vacuum pump filter, and amalgam separator 0.991 Data None Median of amalgam separator efficiencies in

Table 5-1 of Section 5.1

Mercury discharges fromfacilities using only chairside traps 2.00 tons Estimation Product of the ratio of the number of facilities using only chair-side traps to the total number of facilities; the total estimated mercury discharge; and 68% removal efficiency of chair-side traps See Table 6-1 and Section

6.2

Mercury discharges fromfacilities using only chairside traps and vacuum pump

filters 2.38 tons Estimation Product of the ratio of the number of facilities using chair-side traps and vacuum pumps to the total number of facilities; the total estimated mercury discharge; and 81% removal efficiency for the vacuum pump and chair-side

traps See Table 6-1 and Section

6.2

### 6-5 Table 6-4. Determining the Baseline Mercury Discharge to Wastewater

Description Value Type Calculation Source

Mercury discharges from facilities using chair-side traps, vacuum pump filters, and amalgam separators 0.11 tons Estimation Product of the ratio of the number of facilities usingamalgam separators, chairside traps and vacuum pumps

to the total number of facilities; the total estimated mercury discharge; and 99.1% removal efficiency for

the combined treatment

system See Table 6-1 and Section

6.2

Total baseline mercury discharges to POTWs 4.50 tons Result Sum of mercury discharge from facilities using only chair-side traps (2.00 tons); using chair-side traps and vacuum pump filter (2.38 tons); and using chair-side traps, vacuum pump filters, and amalgam separators (0.11 tons)

POTW removal efficiency 0.90 Data None Median POTW removal efficiency (EPA, 1982)

Total baseline mercury discharges to receiving

streams 0.45 tons Result Amount of mercury discharged to receiving

stream after POTW removal (4.50(1-0.9))



### 6.4 Potential Reduction from Instal lation of Amalgam Separators

This subsection presents EPA’ s estimates of the potential mercury reductions due to new installations of amalgam separators. Table 6-5 shows the potential mercury reductions in discharge to POTWs as a result of a mandatory amalgam separator installation programs. This assumes that 100 percent of dental facil ities will install amalgam separators.

Table 6-5. Potentia l Reductions of Mercury to POTWs from Mandatory Installation of Amalgam Separators

Description Value Type Calculation Source

Total baseline mercury discharges to POTWs for facilities that do not operate amalgam separators 4.38 tons Estimation Sum of discharges from facilities that use only chair-side traps (2.00 tons) and vacuum pump filters (2.38 tons) See Table 6-4

Number of additional

facilities that would install 99.2 percent efficiency amalgam separators 73,751 Estimation Sum of facilities that use only chair-side traps (24,584) and vacuum pump filters (49,167) See Table 6-4

### 6-6 Table 6-5. Potentia l Reductions o f Mercury to POTWs from Mandatory Insta l lation of Amalgam S e parators

Descripti o n Value Ty pe Calcul ati o n Source

Mer c ur y d ischar g es af ter
in stallatio n of a m alg a m

sep arat o rs at these facilities 0. 17 5 t o n s Est i m a t i o n P ro d u ct of t h e rat i o of t h e n u m ber

o f

facilities th at wou l d in stall

a m alg a m sep a rato rs t o th e to t a l

n u m b er o f faci lities; th e to tal

est i m a t e d m e rcury di scha r g e; and

99.1% rem oval efficiency for the

com b ined treat ment syste m

. See Table 6-1

, Tabl e 6- 4 , and

Sect i on 6. 2

R e duct i o n of m e rcury di scha rge s t o P O T W s 4

. 2 1 ton s Esti m a tio n D ifferen ce o f baselin e m e rcu r y d i sch a rg es to POTWs for facilities

that do not ope r ate am alga m separat o rs ( 4

. 3 8 to ns ) a n d m e rcu r y d i sch a rg es after in stallatio n of

am al gam separ a t o rs ( 0

. 1 7 5 t o ns)

Total mercur y dischar g es to
POTWs fo llowing

mand a tor y i n stal l a ti o n of

Amal gam Se parators 0.29 tons Result Sum of mercury disc har g ers af

ter i n s tal l a ti on of a m al ga m

sepa ra to rs (0 .1 75 to ns) and f r o mcurrent facilities using chairsi de tr aps , vac uum p ump fi l t ers, and am al gam separ a t o rs ( 0

. 1 1

ton s ). See Ta ble 6-4

POT W rem oval effi ci ency 0. 90 Est i m a t i o n M e di an POT W

rem oval efficie n cy ( E PA , 19 82)

To ta l discha rg es to receiving stre am 0. 02 9 t o ns Resul t Amo u n t of me rcury dischar g ed to receiving s t ream after P O TW removal (0.29(1-0.9))

To ta l reduct i ons to receiving stre am 0. 42 1 t o ns Resul t Di ffere nce of t o t a l b a sel i ne mercury discharge s to recei ving

st ream (0 .45 to ns) a n d to ta l

dischar g es to receiving stre am (0 .0 2 9 t o ns ) See Ta ble 6-4



### 6.5 Annualized Costs for Amalgam Separators

Table 6-6 summarizes the average annualized cost of installing an amalgam separators based on calculations for the first year of purchas e and all subsequent years for the lifetime of the

separator.

### 6-7 Table 6-6. Calculation of Cost

Description Cost ($2008) Reference

First year cost of amalgam separator

unit $2,550.00 Average cost from Table 5-4

Annual cost for amalgam separator after first year $657.00 Average cost from Table 5-4

Lifetime of separator (years) 10 Vandeven and McGinnis, 2005

Interest rate 0.07

Capital recovery factor 0.14

Annualized capital investment cost $363.06

Total annualized cost $1,020.06



### 6.6 Summary and Costs

This subsection summarizes the potential re ductions in mercury discharges expressed in both tons and toxic-weight ed pound equivalents (TWPE). Table 6-7 presents these reductions and the costs of installing amalga m separators to demonstrate the economic impact to the dental industry.

Table 6-7. Summary of Calculations

Calculation Baseline 100% Amalgam Separator

Installation

Tons of mercury discharged to POTW from dental

facilities 4.50 0.29

Tons of mercury discharged to surface water a 0.45 0.029

Mercury TWPE discharged to su rface water (lb-eq ) 105,0 00 6,790

Reduction of mercury discharges to POTWs (tons) 0 4.21

Reduction of mercury discharges to receiving stream (tons) 0 0.421

Reduction of mercury TWPE to receiving stream (lb-eq) b 0 98,200

Number of facilities to install amalgam separators c 0 73,800
Cost to industry ($2008) (assumes 1 separator per facility) $0.00 $75,200,000

a — EPA assumed a POTW removal efficiency of 90 percent. b — Toxic weighting factor for Hg is 117. c — For baseline, EPA assumed that 122,918 de ntal facilities in the U.S. c (see Section 6.1 ) and that 40 percent of these dental facilities use amalgam separators (see Section 6.3 ).



### Table 6-8 presents the 2005 census data used to de termine the percent of dental facilities that currently have amalgam separators installed in the United States.

### 6-8 Table 6-8. Number of Dental Facilities and Amalgam Separator Use by State

State NAICS 621210 Dental

Offices Assumed Percent Operating Amalgam Separators a Estimated Number Operating Amalgam Separators

Alabama 478 0.2 96

Alaska 560 0.2 112

Arizona 263 0.2 53

Arkansas 3,050 0.2 610

California 412 0.2 82

Colorado 1,732 0.2 346

Connecticut b 9,017 1 9,017

Delaware 4,546 0.2 909

District of Columbia 5,258 0.2 1,052

Florida 4,357 0.2 871

Georgia 2,334 0.2 467

Hawaii 5,639 0.2 1,128

Idaho 4,353 0.2 871

Illinois 2,023 0.2 405

Indiana 1,922 0.2 384

Iowa 1,077 0.2 215

Kansas 2,153 0.2 431

Kentucky 259 0.2 52

Louisiana 267 0.2 53

Maine b 790 1 790

Maryland 1,016 0.2 203

Massachusetts b 243 1 243

Michigan 2,483 0.2 497

Minnesota c 315 0.85 268

Mississippi 2,845 0.2 569

Missouri 573 0.2 115

Montana 2,720 0.2 544

Nebraska 1,368 0.2 274

Nevada 3,024 0.2 605

New Hampshire b 6,733 1 6,733

New Jersey b 1,586 1 1,586

New Mexico 2,110 0.2 422

New York b 1,417 1 1,417

North Carolina 846 0.2 169

North Dakota 933 0.2 187

Ohio 1,527 0.2 305

Oklahoma 1,325 0.2 265

Oregon b 7,597 1 7,597

Pennsylvania 414 0.2 83

Rhode Island b 656 1 656

South Carolina 222 0.2 44

### 6-9 Table 6-8. Number of Dental Facilities and Amalgam Separator Use by State

State NAI CS 6 2 1 2 1 0 Dent al

Offices Assume d Perc ent Operating Amalgam Separ a tors a Estimated Number Operating Amalgam Separ a tors

So ut h Da kot a 2, 36 6 0. 2 47 3

Ten n essee 59 3 0. 2 11 9

Texas 2, 20 9 0. 2 44 2

Ut ah 1, 41 8 0. 2 28 4

Verm ont b 88 3 1 88 3

Vi r gi ni a 3, 18 3 0. 2 63 7

Was h in gto n c 1, 82 5 0. 8 1, 46 0

West Vi rgi n i a 19 ,0 0 5 0. 2 3, 80 1

W i sco n si n 30 7 0. 2 61

W y om i ng 68 6 0. 2 13 7

T ot al U

. S. 12 2, 9 18 49 ,0 2 1

Percent of Total De ntal Offi ces 40%

Source: Census, 2005. a — Assumes 100 percent compliance with mandatory programs, uses Table 4-7 in Section 4 for state voluntary program participation rates, and assumes 20% for states with no information. b — State requires amalgam separators. c — State has voluntary program for installation of amalgam separators with information on participation rates in

Section 4

.

### 7-1 7. R EFERENCES



### ACS. 2008. American Chemical Society. “Dental Of fices Contribute to Methylmercury Burden: Bacteria That Methylate Mercury Thrive in Wastewater Found Do wnstream from Dental Traps.” Environmental Science & Technology Online News. 12 March. http://pubs.acs.org/subscribe /journals/esthag-w/2008/mar/sc ience/nl_dental.html. DCN 05456.

ACWA. 2007. Oregon Association of Clean Wate r Agencies. “EPA Comment Letter — Docket ID No. EPA-HQ-OW-2006-0771.” December.

ADA. 2007a. American Dental Association. Best Management Practices for Amalgam Waste. Updated July 2007. DCN 04244.

ADA. 2007b. American Dental Association. Survey and Economic Research on Dentistry, Frequently Asked Questions: How Many Dentists Are There in the U.S.? http://www.ada.org/ada/prod/survey/faq.asp#howmany. DCN 05992.

ALISON. 2007. Alabama Legislative Information System Online. Regular Session 2004. http://alisdb.legislature.state. al.us/acas/ACASLogin.asp. DCN 05993.

AMSA. 2002. Association for Metropolitan Sewerage Agencies. Mercury Source Control and Pollution Prevention Program Evaluation, Final Report. EPA-HQ-OW-2006-0771-0849[1].9. July. DCN: 04225.

Anderson, N. 2007. Statement of Norris Anderson, P h.D., Director, Office of Science and Health Coordination, FDA. November 14. http ://www.fda.gov/ola/2007/dentalmercury111407.html.

DCN 05979.

APHA, AWWA, and WEF: Standard Methods for the Examination of Water and Wastewater, 1998. Washington, DC. DCN 06113.

Arkansas. 2003. State of Arkansas 84th General Assembly, Regular Session, 2003. House Bill 1309: An Act to Reduce the Incidence of Me rcury Poisoning in Arkansas, and for Other Purposes . http://www.arkleg.state.ar.us /ftproot/bills/ 2003/public/hb1309/hb1309- 112620021319.pdf. DCN 04670.

Batchu, H., et al. 2006. “Evaluating Amalgam Sepa rators Using an Inte rnational Standard.” Journal of the American Medical Association 137:999–1005. DCN 04240.

Batchu H, et al. 2006a. JADA Continuing Education. Th e effect of disinfectants and line cleaners on the release of mercury from amalgam. Journal of American Dental Association , Vol 137, No 10, 1419-1425. DCN 06101.

Bates, T.B. 2006. “Dentists Aim: Keep Mercury out of Drains.” Asbury Park Press . December

17. DCN 04181.

Behm, D. 2008. “Dentists Filtering Out Mercur y But Nearly One-fifth Miss MMSD Deadline.”

Milwaukee Journal Sentinel. February 9. DCN 05464.

### 7-2 BLS. 2006a. Bureau of Labor Statistics. Occupational Employment and Wages, 2006, Plumbers, Pipe Fitters and Steamfitters. DCN 04694.

BLS. 2006b. Bureau of Labor Statistics. Occupational Outlook Handbook, 2006-07 Edition,

Dentists. DCN 04695.

Boston University. 1998. Boston University Corporate Education Center. A New Prescription: Pollution Prevention Strategies for the Health Care Industry. October 7. DCN 00144.

Cain. 2007. Alexis Cain et al. Substance Flow Analysis of Hg In tentionally Used in Products in

the United States. Journal of Industrial Ecology. v. 11, No. 3, pp. 61-75. DCN 06100.

California Legislative Counsel. 2005. Complete Bill History, Bill Number: AB No. 966. http://www.leginfo.ca.go v/pub/05-06/bill/asm/ab_0951-1000/ ab_966_bill_20060929_history.html. DCN 05994.

Carver, D.J. 2008. Environmental Protection Agen cy and Marquette University School of Dentistry. Draft Course Material; Presentation on Dental Amalgam Recycling: Pathways, Principles, and Practice. August. DCN 06136.

Census. 2004. U.S. Census Bureau. Dental Laboratories: 2002. “I ndustry Statistics by Employment Size: 2002.” 2002 Economic Census, Manufacturing . Subject Series. EC02-311- 339116 (RV). December.

Census. 2005a. U.S. Census Bureau. “I ndustry Code Comparison: 339116 and 621210.” County

Business Patterns: 2005. http://censtats.cen sus.gov/cgi-bin/cbpna ic/cbpsel.pl. DCN 04504.

Census. 2005b. U.S. Census Bureau. Establishmen t and Firms Size: 2002 (Including Legal Form of Organization). “Receipts/Rev enue Size of Establishments for the United States: 2002.” 2002 Economic Census, Health Care and Social Assistance. Subject Series. EC02-62SS-SZ.

November. DCN 04505.

Census. 2005c. U.S. Census Bureau. Establishm ent and Firms Size: 2002 (Including Legal Form of Organization). “Single Unit and Multiunit Firms for the United States: 2002.” 2002 Economic Census, Health Care and Social Assistance . Subject Series. EC02-62SS-SZ. November. DCN

02942.

Census. 2005d. U.S. Census Bureau. Establishmen t and Firms Size: 2002 (Including Legal Form of Organization). “Legal Form of Organization of Establishments Subject to Federal Income Tax

for the United States: 2002.” 2002 Economic Census, Health Care and Social Assistance. Subject Series. EC02-62SS-SZ. November. DCN 02943.

Census. 2007a. U.S. Census Bureau. “Bridge Between NAICS and SIC Manufacturing.” http://www.census.gov/epcd/ec97brdg/E 97B1339.HTM#339992. Accessed July 2007. DCN

04507.

Census. 2007b. U.S. Census Bureau. “Bridge Betw een NAICS and SIC Health Care and Social Assistance.” http://www.census.gov/epcd /ec97brdg/E97B1621.HTM#6212. Accessed July 2007.

DCN 04508.

### 7-3 Columbia. 2005. Columbia University Dental Sc hool Course Materials. October 19, 2005. “Class II Amalgam Restoration.” http://www.columbia. edu/itc/hs/dental/operative/amalgam.html. Accessed September 19, 2007. DCN 04999A1.

Condrin, A.K. 2004. “The Use of CDA Best Manage ment Practices and Amalgam Separators to Improve the Management of Dental Wastewater.” Journal of the California Dental Association 32(7):583-592. DCN 02834.

CTDEP. 2006. Connecticut Departme nt of Environmental Protection. Dental Use of Mercury. http://www.ct.gov/dep/cwp/view.asp?a= 2708&q=323994&depNav_GID=1638. December 18.

DCN 04671.

EBMUD. 2002. “Amalgam in Dental Office Wastewater: Addressing the Issue.” Journal of the

American Medical Association 133(5):585-589. DCN 02234.

EBMUD. 2004. East Bay Municipal Utility District . Table of ISO Standard 11143 Certified Amalgam Separators. Available at http://www.ebmud.com/wastewater/industrial_&_commercial_permits_&_fees/pollution_preven tion_program/mercury%20program/amalgam%20separators%20a nnual%20cost%202003.pdf.

DCN 04200.

EBMUD. 2005. East Bay Muni cipal Utility District. Pollution Prevention Program. January.

DCN 04199.

EBMUD. 2007. East Bay Muni cipal Utility District. Pollution Prevention Program: Pollution Prevention Highlights for 2006. DCN 04229.

EPA. 1982. Effluent Guidelines Division. Fate of Priority Pollutants in Publicly Owned

Treatment Works . EPA 440/1-82/303. Washington, DC. (September). DCN 03527.

EPA. 2003. U.S. Environmental Protection Agency. Options for Dental Mercury Reduction Programs: Information for State/Provincial and Local Governments. A Report of the Binational Toxics Strategy Mercury Workgr oup. 16 December. Available at http://www.epa.gov/region5/air/merc ury/dentaloptions3.pdf. DCN 00799.

EPA. 2005. U.S. Environmental Protection Agenc y, Region 8 Industrial Pretreatment Program. POTW Mercury Control Strategy. May 9. http://www.epa.gov/region8/water/pretreatment/
Pret_download/R8%205-9-05%20Final%20Dra ft%20Hg%20Control%20Strategy.pdf. DCN

04228

EPA. 2006. U.S. Environmental Protection Agency. Notice of Availability of Final 2006 Effluent Guidelines Program Plan. 21 December. DCN 02377.

EPA. 2007a. U.S. Environmental Protection Agency. State Mercury Medical/Dental Waste Programs. http://www.epa.gov/epaoswer/hazwaste/mercury/medical.htm. DCN 04676.

EPA. 2007b. U.S. Environmental Protection Agency. Memorandum to the Public Record for the 2008 Effluent Guidelines Program Plan EPA Docket Number EPA-HQ-OW-2006-0771:

“American Dental Associati on Meeting Summary (20 November 2007).” 27 November. DCN

06137.

### 7-4 Fan, P.L., et al. 2002. “Laboratory Evaluation of Amalgam Separators.” Journal of the American

Medical Association 133:577-584. DCN 02233.

FDA. 2008. “Questions and Answ ers on Dental Amalgam.” http://www.fda.gov/cdrh/consumer/amalg ams.html. Accessed August 18, 2008.DCN 06130.

FLDEP. 2001. Florida Department of Environmental Protection. Best Management Practices for Scrap Dental Amalgam: Guidelines for Dental Offices. October. DCN 04192.

Great Lakes. 1998. Great Lakes Binational Toxics Strategy Stakeholder Forum. Background Information on Mercury Sources and Regulations. http://www.epa.gov/glnpo/bnsdocs/mercsrce/me rcreg.html. Accessed March 14, 2008. DCN

00130.

Grubbs, G. 2003. Statement of Ge offrey Grubbs, Dir ector, Office of Science and Technology, United State Environmental Protection Agency before the Subcommittee on Wellness and Human Rights of the Committee on Govern ment Reform, United States House of Representatives. 8 October. DCN 03034.

HERCenter. 2008. Healthcare Environmental Resource Ce nter — Best Management Practices for Common Dental Office Wastes. http://www.hercenter.org/dentistwastes.cfm. Accessed March 14, 2008. DCN 05991.

ISDA. 2008. Idaho State Dental Association. Best Management Practices (BMPs) for Dental Offices. http://www.cityofboise.org/Departments/ Public_Works/PDF/ISDADentalBMPs.pdf. Accessed February 2008. DCN 05980.

ISO. 1999. International Organi zation for Standardization. Dental Equipment—Amalgam Separators. ISO 11143. Geneva, Switzerland: Internati onal Organization for Standardization.

DCN 04697.

Johnston, C. 2005. U.S. Environmental Protection Agency. Memorandum to the Public Record for the 2006 Effluent Guidelines Program Pl an. “Industry Sectors Being Evaluated Under Proposed ‘Health Services Industr y’ Category.” 4 August. DCN 02293.

KCWTD. 2007. King County Wast ewater Treatment Division. King County Regulations for Dental Wastewater Discharged to the Sewer. May 16. http://dnr.metrokc.gov/wlr/

indwaste/dentists.htm. DCN 04677.

King County. 2008. “Mercury Levels in King County Biosolids.” http://dnr.metrokc.gov/wlr/indwaste/ama lgdiff.pdf. Accessed March 19, 2008. DCN 05995.

Lamperti, L. 2007. City of Corvallis’ Comments on EPA’s Preliminary 2008 Effluent Guidelines Program Plan. December 21. OW-2006-0771-0857.

MassDEP. 2007. Massachusetts Department of Environmental Protection. Dental Amalgam/Mercury Recycling Program. http://www.mass.gov/dep/service/dentists.htm. DCN

04678.

### 7-5 MCES. 2001. Metropolitan Counc il Environmental Services. Evaluation of Amalgam Removal Equipment and Dental Clinic Loadings to the Sanitary Sewer. 21 December. DCN 02232.

McManus, K.R., and P.L. Fan. 2003. “Purchasing, Installing and Opera ting Dental Amalgam Separators.” Journal of the American Dental Association 134:1054-1065. DCN 06001

MDA. 2003. Minnesota Dental Association. Re: Amalgam Recovery. March. http://www.mndental.org/client_files/ documents//amalgam_recovery.pdf. DCN 04679.

MEDEP. 2005. Maine Department of Environmental Protection. Dental Amalgam. http://www.maine.gov/dep/blwq/topic/am algamseparator/index.htm. DCN 04999.

MMSD. 2008. Madison Metropoli tan Sewerage District. MMSD Mercury Pollutant Minimization Program. http://www.madsewer.org/mercury.htm. Accessed February 2008. DCN

06135.

MU Extension. 2007. Marie Steinwachs. Univers ity of Missouri Extension Environmental

Assistance Center. “Maximizi ng Voluntary Reductions in Dent al Amalgam Mercury: Reduction in Mercury Discharges.” EPA#E0 000127. P1-98765101-0. November DCN 06139.

NACWA. 2006. National Associati on of Clean Water Agencies. Controlling Mercury in Wastewater Discharges from Dental Clinics . January. DCN 04187.

NACWA. 2007a. An Examination of Mercury Levels at Clean Water Agencies 2003-2006. EPAHQ-OW-2006-0771-0849[1].3. December 18.

NACWA. 2007b. National Associati on of Clean Water Agencies. ACWA Comments on ELG Preliminary Plan. EPA-HQ-OW-2006-0771-0849. December.

NEORSD. 2007. Northeast Ohio Regional Sewer District. Mercury Program: Annual Report Form for Dental Care Practices, 2006. http://www.neorsd.org/internet/do/ viewProgram.do?programId=21. DCN 05996.

NHDES. 2002. New Hampshire Departme nt of Environmental Services. Best Management Practices for Dental Offices in New Hampshire. January. http://www.des.state.nh.us/ nhppp/dentalBMP.pdf. DCN 04685.

NJR. 2007. New Jersey Register. Requirements for Indirect Us ers — Dental Facilities. 39 NJR 4117(a). October 1. DCN 06138.

NSF. 2001. Protocol for the Verification of Me rcury Amalgam Removal Technologies. DCN

04179.

NYDEC. 2007. New York State Department of Environmental Conservation. Managing Dental Mercury. http://www.dec.ny.gov/chemical/8513.html. DCN 04686.

Oregon. 2007. Oregon State Legislature. Senate Bill 704: An Act Relating to Mercury in Dental

Wastewater. June. http://landru.leg.state.or.us /07reg/measures/sb0700.dir/sb0704.en.html. DCN

004687.

### 7-6 OSHA. 1997. Occupational Safety and Health Admi nistration. “The Dental Industry’s Concerns Regarding Compliance with Certain Provisions of the Hazard Communication Standard (HCS).”

Letter to the American Dental Trade Association. February 6. http://www.osha.gov/pls/oshaweb/ owadisp.show_document?p_table=INTERPRETATIONS&p _id=22343. DCN 05997.

PACE. 2007. Partners for A Clean Environment. Amalgam Separator Buyer’s Guide. Spring

2007. Available at http://www.ci.boulder.co.us/www/pace/documents /AmalgamSeparatorBuyersGuide.pdf. DCN

05989.

Palo Alto. 2007. City of Palo Alto Regional Water Quality Control Plant. Advanced Mercury Source Control Study: 2006 A nnual Report of Activity. February. DCN 04235.

RIDEM. 2007. Rhode Island Department of Environmental Management. Mercury in Dental Amalgam. http://www.dem.ri.gov/topics/mercury.htm. DCN 05990.

RMA. 2007. Risk Mana gement Association. Annual Statement Studies 2006/2007. DCN 04501.

SBA. 2006. U.S. Small Business Administration. Table of Small Business Size Standards

Matched to North American I ndustry Classification Codes. Effective 31 July. DCN 04510.

Singer, D. 2007a. ERG. Current Federal, State, Local and Industry Group Requirements and Guidance to Control Mercury Discharges from Dentists. July 17. DCN 04668.

Singer, D. 2007b. ERG. “Dental Amalgam Separa tors: Summary of Removal Efficiencies,

Current Use and Cost Effectiveness.” Memora ndum from ERG to Jan Matuszko, EPA. Docket ID No EPA-HQ-OW-2006-0771-0224. September 26. DCN 04851.

Stone, M.E., et al. 2002. “Determination of Meth yl Mercury in Dental-Unit Wastewater.” Dental

Materials 19:675-679. DCN 02836.

Stone, M.E. 2004. “The Effect of Amalgam Separators on Mercury Loading to Wastewater

Treatment Plants.” Journal of the California Dental Association 32(7):593-600. DCN 02828.

TheWealthyDentist.com. 2007. “Dentists Split Over Amalgam Use.” http://www.thewealthydentist.com/surveyresults/16_MercuryAmalgam_ Results.htm. Accessed August 18, 2008. DCN 06129.

Troy, L. 2007. Almanac Financial of Busi ness and Industrial Ratios. 2007 Edition. CCH. Chicago, IL. DCN 04502.

Uva, T.P. 2007. Narragansett Bay Commission’s (NBC) Comments on EPA’s Preliminary 2008 Effluent Guidelines Program Plan. EPA-HQ-OW-2006-0771-0861. December 27.

UW. 2008. University of Wisconsin. Take the Bite out of Dental Amalgam Waste Workshop: Breakout Group Recommendations . 30 April. DCN 06180.

Vandeven, J., and S. McGinnis. 2004. “Cost-Eff ectiveness of Removing Amalgam from Dental

Wastewater.” California Dental Association Journal 32(7):564-573. DCN 02831.

### 7-7 Vandeven, J., and S. McGinnis. 2005. “An Assessmen t of Mercury in the Form of Amalgam in

Dental Wastewater in the United States.” Water, Air and Soil Pollution 164: 349-366. DCN

04698.

Vandewall, K.S. 2007. U.S. Air Force Dent al Evaluation and Consulting Service. Dental Amalgam. https://decs.nhgl.med.navy.mil/DOWNLOAD/amalgam.ppt. Accessed September 19,

2007. DCN 04999.

VTDEC. 2006. Vermont Department of Environmental Conservation. Environmental Management for Dental Offices. September 19. http://www.mercvt.org/dental/index.htm. DCN

04690.

WA Department of Ecology. 2006. Washington State Department of Ecology, Hazardous Wastes and Toxics Reduction Program. Memorandum of Understanding De ntal Compliance Follow-Up Report. Publication Number 06-04-011. Jul y. http://www.ecy.wa.gov/pubs/0604011.pdf. DCN

04675.

Walsh. 2007. Pepper Hamilton, LLP. The American Dental Associ ation’s (ADA) Comments on EPA’s Study of a Pretreatment Re quirement for Dental Amalgam. OW-2006-0771-0837.

December 21.

WDA. 2004. Wisconsin Dental Association. Amalgam Management for Dental Offices. September. http://www4.uwm.edu//shwec/publica tions/cabinet/pdf/Den talAmalgam04.pdf. DCN

05518.

WI DNR. 1997. Wisconsin Depart ment of Natural Resources. Wisconsin Mercury Sourcebook. http://www.epa.gov/glnpo/bnsdocs/ hgsbook/. Accessed March 2008. DCN 05459