Dental Mercury and Environmental Issues->Publications->Mercury Hygiene Best Management Practices

Mercury Hygiene Best Management Practices

The American Dental Association has published recommendations for the appropriate use and handling of dental amalgam [1].

These recommendations are briefly summarized here:

Training of all personnel about the need for appropriate hygiene practices when working with amalgam and amalgam-contaminated instruments. Training should include the presentation of relevant environmental and waste management regulations. These regulations may vary on a state-by-state basis, and local dental societies should be contacted when information about disposal regulations is needed. An excellent Hg hygiene training presentation is available through the United States Air Force Dental Investigation Service web site [2].

Work areas should be well ventilated to prevent the build up of Hg vapor. Patient treatment and work areas should be monitored for Hg vapor on a routine basis and in the event of Hg spills. Industrial hygienists trained in the use of Hg vapor analyzers should do the monitoring.

Flooring should be nonabsorbent, seamless and easy to decontaminate.

Use only predosed precapsulated amalgam. Bulk Hg should be turned in or sold to recyclers.

Use of amalgamators with enclosed mixing areas that will contain any Hg that leaks out during trituration.

Avoid handling freshly mixed amalgam or Hg with unprotected skin. Used amalgam capsules should be recapped and disposed of appropriately.

High-volume oral evacuation equipment should be used when placing, finishing or removing amalgam.

Amalgam traps should be cleaned out daily and the used amalgam should be collected for recycling.
Amalgam traps should never be rinsed in sinks or into the high-volume evacuation lines.

Scrap amalgam should be stored dry in a tightly capped container. Storing scrap amalgam under photographic or radiographic fixer creates disposal problems for the fixer solution and some amalgam recyclers will not accept wet amalgam scrap.

Never dispose of Hg contaminated wastes into containers that will be incinerated, e.g. red bag or infectious waste. Incineration of used capsules should be avoided to avert volatilization of Hg to the atmosphere. Deposition of atmospheric Hg to land, lakes, rivers, and streams can be substantial [3] and lead to the creation of organic Hg that bioaccumulates in fish and other aquatic organisms [3 - 11]. Nearly 100% of the Hg that concentrates in fish tissue is methyl mercury [3, 8]. High Hg levels in remote pristine lakes, where atmospheric deposition appears to be the key instrument of contamination, is further evidence of the importance of this pathway.

Clean up spills using trap bottles, tapes, or freshly mixed amalgam. Amalgam spill kits are also available commercially [12]. Never "vacuum" Hg with the high-volume evacuation system, as this will release Hg to the wastewater stream. Household vacuum cleaners should never be used to clean up Hg spills as this can volatize Hg and will contaminate the vacuum.

Dental Amalgam Recyclers:

Business Name	Phone	Address
Advanced Environmental Recycling Corp.	(800) 554-2372	2591 Mitchell Avenue, Allentown, PA 18103
Amalgaway, Inc.	(800) 267-1467	1002 W. Troy Avenue, Indianapolis, IN 46225
Bethlehem Apparatus Company	(610) 838-7034	PO Box Y, Hellertown, PA 18103
Enviro-Chem, Inc.	(763) 428-4002	21821 Industrial Blvd., Rodgers, MN 55374
Maguire and Strickland Refining Co.	(800) 486-2858	1290 81^st Avenue NE, Minneapolis, MN 55432
Mercury Waste Solutions, Inc.	(800) 741-3343	21211 Durand Avenue, Union Grove WI 53182
Superior Special Services	(508) 886-0150	5736 W. Jefferson Street, Phoenix, AZ 85043

References

1. Dental mercury hygiene recommendations. ADA council on Scientific Affairs. J Am Dent Assoc 1999 Jul; 130(7): 1125-6.

2. United States Air Force Dental Investigation Service. "Mercury Hygiene Briefing – Designed to help local facilities with issues concerning Mercury Hygiene". http:// www.brooks.af.mil /dis /DOWNLOAD/hghygiene.ppt (27 November 2000).

3. United States Environmental Protection Agency. Mercury Study Report to Congress. Office of Air Quality Planning & Standards and Office of Research and Development. December 1997. EPA-435/R-97-003.

4. Hamdy MK and Noyes OR. Formation of methyl mercury by bacteria. Appl Microbiol 1975; Sep 30(3): 424-32.

5. Dunlap L. Mercury: Anatomy of a pollution problem. Chem Engineering News, 1971; 49:22-25.

14. Compeau GC and Bartha R. Methylation and demethylation of mercury under controlled redox, pH and salinity conditions. Appl Environ Microbiol 1984; 48(6): 1203-7.

6. Gilmour CC and Riedel GS. Measurement of Hg methylation in sediments using high specific-activity ²⁰³Hg and ambient incubation. Wat Air Soil Pollut 1995; 80:747-756.

7. Gilmour CC, Henry EA and Mitchell R. Sulfate stimulation of mercury methylation in freshwater sediments. Environ Sci Technol 1991; 26:2281-2287.

8. Gilmour CC, Riedel GS, Ederlington MC, Bell JT, Beniot JM, Gill GA and Stordal MC. Methyl mercury concentrations and production rates across a trophic gradient in the Northern Everglades. Biogeochem 1998; 40:326-346.

9. Rudd JWM. Sources of methylmercury to freshwater ecosystems: A review. Water Air Soil Pollut 1995; 80:697-713.

10. Xun L, Campbell NER and Rudd JWM. Measurement of specific rates of net methylmercury production in the water column and surface sediments of acidified and circumneutral lakes. Can. J. Fish. Aquat Sci 1987; 44:750-757.

11. Jensen S and Jernelov A. Biologic methylation of mercury in aquatic organisms. Nat 1969; 223:753-754.

12. United States Air Force Dental Investigation Service. "Synopsis of Mercury Spill Kits".http://www.brooks.af.mil/dis/DIS60/sec6b.htm (27 November 2000).