State/local amalgam separator/BMP programs

US Navy separator/BMP program Regulated Medical Waste vs. Hazardous

Waste concerns US EPA Office of Solid Waste dental

school initiative Dental chairside trap designs Hg vapor issues

2

Amalgam separators must be installed by May 2008

All dental facilities that “apply, alter, maintain, remove, or dispose of amalgam”

Excludes orthodontists, periodontists, prosthodontists, and Oral Surgeons

Separators must be 99% efficient Separator waste must be disposed of

within one year

New York

3

All dentists must recycle amalgam waste Maintain written certification of recycling Dentist must notify local sewer authority

that separator is installed New offices must install separators prior

to opening Amalgam waste cannot be disposed of in

trash, medical waste containers, or sterilized in autoclaves

Pre-encapsulated amalgam only (elemental Hg banned)

New York

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Milwaukee Metropolitan Sewerage District (MMSD) requiring separators to be installed by February 1, 2008

MMSD serves 28 municipalities 317 total amalgam using offices in

district Currently 184 amalgam using offices

with separators installed (58%) Point of contact: Tom Nowicki, (414)

225-2275

Milwaukee, Wisconsin

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Milwaukee, WisconsinInfluent Mercury

0

100

200

300

400

500

600

700

9/17

/03

11/1

7/03

1/17

/04

3/17

/04

5/17

/04

7/17

/04

9/17

/04

11/1

7/04

1/17

/05

3/17

/05

5/17

/05

7/17

/05

9/17

/05

11/1

7/05

1/17

/06

3/17

/06

5/17

/06

7/17

/06

9/17

/06

11/1

7/06

Mer

cury

(n

g/L

)

Jones Island South Shore Linear (South Shore) Linear (Jones Island)

Data from Tom Nowicki, Milwaukee County Sewerage District6

Separators and BMPs required in Dane County (Madison) by 12/31/2008

Seven major Wisconsin municipalities will also require separator installations by 2008 (GLWQI – 1.3 ng/L)

Wisconsin Dental Association is cooperating with separator effort

Contact Randy Case of the Wisconsin DNR for more information (608) 267-7639

Wisconsin Statewide

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NSSD is 2nd largest POTW in Illinois No discharge directly to Lake Michigan Mandated Pretreatment systems at Naval

Base, Great Lakes Completed survey of all dentists in service

area Working towards a program requiring BMPs

and/or separators in near future Point of Contact: Sharon R. Thieszen (847)

623-6060

Gurnee, Illinois NSSD

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Separators or permits required for all dental offices placing and/or removing amalgam

MCES Maintains a list of approved separators

99% removal efficiency with ISO 11143 Testing and certification Works closely with Minnesota Dental

Association Point of Contact: Peter Berglund of MCES,

(651) 602-4708

Minneapolis/St. Paul Metro Area 7 Counties

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Voluntary effort organized by Tim Tuominen of the WLSSD

Installed separators in all dental offices serviced by WLSSD

Works with Northeast District Dental Society (MDA)

WWTP influent is down and effluent is approaching the GLWQI level of 1.3 ng/L

Point of Contact is Tim Tuominen (218) 740-4815

Duluth, Minnesota

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Connecticut (95%), Maine (95/98%, list of approved separators), New Hampshire, Vermont, Rhode Island (eastern half of state)

Massachusetts requires 98% ISO 11143 efficient separator or equivalent method acceptable to MassDEP

VT and CT include separators in BMPs and require dentists to implement BMPs

Washington requires installation of ISO 11143 separators statewide

Non-Great Lakes States/Areas

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New Jersey is working on a requirement for separators

Montana Draft Bill 1262 would require amalgam separators and recycling of amalgam waste

Warren Air Force Base, Cheyenne, Wyoming required to install amalgam separators in dental clinics

Non-Great Lakes States/Areas

12

Wichita, Kansas requires ISO 11143 separators

San Francisco Bay area East Bay Municipal Utility District Contra Costa Central Sanitation

District Union Sanitary District

Palo Alto Sanitary District Toronto (one of earliest requirements) Montreal

13

Non-Great Lakes States/Areas

Navy is installing separators in all dental treatment facilities

US, overseas, and ships Installing systems that remove both

particulate and dissolved Hg Also installing chairside filtration

systems that remove particulate and protect downstream plumbing lines

Working on non-mercury filling materials 14

Disposable filter elements are housed inside reusable chambers

Filter elements are made from spun polypropylene

6 inch filter element has a vendor claimed surface area of ~2.2 square feet (depth filtration)

Cost of a disposable filter element is less than $2.00 a piece

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Pore Size 50 m 15 m 1 m 0.5 mMean Hg 79.13 23.55 17.68 4.25

Sample Size 50 50 50 50

SD 71.40 23.25 17.35 6.35

Baseline Hg levels without any chairside filtration system averaged 1,087.38 mg (n=50, SD=993.92)

Units are in mean mg of Hg per dental chair per day

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Pore Size 50 m 15 m 1 m 0.5 m

% Removal

92.72 97.83 98.86 99.61

Calculated removal efficiencies = (B Hg – F Hg / B Hg) x 100; where B Hg is the baseline Hg level, F Hg is the amount of particulate Hg collected after the chairside filter)

Baseline Hg levels without any chairside filtration system averaged 1,087.38 mg (n=50, SD=993.92)

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Empty Full Pass ISO

0.5m 97.5% 96.8% Yes

15m 94.8% 96.1% No

The 0.5 m filter passed at 96.8% The 15 m filter failed at 94.8% Currently testing the 1.0 and 5.0 m filters with the

ISO protocol ISO 11143 protocol is currently up for revision to

close the “loophole” of flow rate and other changes (The threshold for maximum testing will be 1 liter/minute, where there was no threshold before)

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Reusable filter chambers require periodic cleaning to remove debris

A disposable unit has been developed to address this issue

19

Chairside filtration systems substantially reduce Hg emissions into wastewater

Low cost and minimal maintenance 0.5 m filter passed ISO 11143 protocol Location at the chair protects

downstream plumbing lines from amalgam debris

Minimal impact on vacuum levels at the HVE tip

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In some locations amalgam waste is both a regulated medical waste (Potentially Infective Medical Waste, PIMW) and a hazardous waste

In Illinois teeth, contiguous bond and gum are excluded from PIMW classification

Some recyclers require a “certificate of disinfection” before they will accept dental waste

Medical waste is routinely incinerated or autoclaved which would release Hg to atmosphere

21

EPA is seeking to partner with US Dental Schools to develop a curriculum based dental recycling program

Student dentists Practicing dentists though CE

Gray Bag program (ANSI/ADA Specification 109)

Point of contact is David Carver, USEPA OSW (703) 308-8603

22

Standard procedure to collect, store, and prepare amalgam waste for shipment to recyclers

Disinfecting of wastes (if required by recyclers)

Keep written records: mass, name and address or recycler, etc.

Wastes include extracted teeth with amalgam fillings

23

Scrap amalgamContactNon Contact

Used capsules Chairside traps Extracted teeth with amalgam

fillings Amalgam from amalgam

separators and vacuum pump filters 24

Landfills vs. Retorting Facilities Need for the disinfection of

amalgam waste? Universal Waste Laws

Ease regulatory burdens Promote proper recycling,

treatment, or disposal Provide for collection

opportunities 25

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Most dental chairs have built in chairside traps

While not originally designed to function as amalgam separators, chairside traps remove substantial amounts of amalgam waste

There is confusion in the literature concerning pore sizes of traps

This project used image analysis to obtain more accurate estimates of trap pore sizes from four selected chairside traps

27

Uncovered type trap

Trap used in new ADEC Dental chairsCovered trap

28

Example of an inline chairside trap after 5 days of use

29

SEM of amalgam waste from removal of amalgam restorations. Note that

the particles have high aspect ratios.30

Length,μm

Width,μmFeret’s

1,μmAspect 2

Trap 1 n=99

1156.76 (108.81)

1121.51(103.51)

1348.95(21.56)

1.03(1.01)

Trap 2n=110

1126.61 (233.73)

1038.54(293.90)

1239.74(242.77)

1.41(4.56)

Trap 3n=200

749.18 (77.79)

600.44 (122.99)

889.45 (87.36)

1.43(1.44)

1 Feret’s Diameter is the greatest dimension between any two points along the boundary

2 Aspect is the ratio of the longest dimension to shortest dimension

Table 1: Mean and Standard Deviations (SD) from Traps with Square Pores

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Table 2: Mean and Standard Deviations (SD) Trap with Round Pores – Trap 4

Diameter,μm (max)

Diameter,μm

(min)

Diameter,μm

(mean)Roundness 3

Trap 4n=199

936.18(29.07)

894.63 (79.55)

918.84 (55.00)

1.37(1.96)

3 Roundness is a measure of how far the pore shape differs from a circle

32

Trap 1 – DentalEZ

33

Trap 2 – Pinnacle Products, Inc.

34

Trap 3 – Pinnacle Products, Inc.

35

Trap 4 – Parts Warehouse, Inc.

36

All traps had at least one dimension greater than 700μm

When traps are the only Hg abatement mechanism, our findings suggest greater potential for Hg emissions than was previously assumed

Manufacturers have the opportunity to contribute to the reduction of environmental Hg contamination

Covered traps help prevent waste amalgam from entering plumbing lines

37

Recycling means that more amalgam waste is “stored” in dental treatment rooms

May result in Hg vapor levels exceeding human exposure limits

Another issue is Hg vapor levels in exhaust air from dental vacuum systems

38

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A Permissible Exposure Limit for Hg vapor is a time weighted average for an 8-hour workday and a 40-hour workweek. This is the legally enforceable limit for the workplace

B Recommended Exposure Limit for Hg vapor for up to a 10-hour workday and 40-hour workweek

C Hg threshold limit value as a time weighted average for an 8-hour workday and a 40-hour workweek

Federal OSHA PELA 8-Hour TWA 0.1 mg/m3 (100,000 ng/m3)

NIOSH RELB 8-Hour TWA 0.05 mg/m3 (50,000 ng/m3)

ACGIH TLVC 8-Hour TWA 0.025 mg/m3 (25,000 ng/m3)

40

Location Hg Vapor Levels

Open Oceans 1-2 ng/m3

Urban Atmosphere 2-20 ng/m3

Coal-Fired Power Plants

(Combustion zone)1,000-20,000 ng/m3

Great Lakes, IL, USA 13.2 ng/m3

41

We’ve surveyed a number of dental operatories

Hg vapor levels in breathing zone is well below OSHA/NIOSH/ACGIH exposure levels

Hg vapor levels inside recycling containers can exceed exposure levels

Care should be taken when opening containers 42

Clinic I(110 chairs)

Clinic II(30 chairs)

Clinic III(2 chairs)

Hg, ng/m3 45,316 73,737 35,421

ng of Hg/min

532,684 131,353 18,079

43

Mean for all three clinics and both methods was 51,684 ng/m3

Exhaust air form dental vacuum systems contains 3,915 times more Hg than ambient air samples

Exhaust air from dental vacuum systems had 2.6-to-51.7 times higher concentration of Hg than flue gas from combustion zones in coal-fired power plants

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