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The Naval Dental Research Institute and Removal of Mercury from Dental Amalgam Wastes

Publications Technologies
Speakers Bureau Coursework Inventory


Dental Mercury Sponsored by


This Dental Mercury Environmental Issues Website was developed to provide a resource for the management of mercury in the dental-unit wastewater stream. This Website is supported by a grant from the Great Lakes National Program Office of the United States Environmental Protection Agency: Interagency agreement number DW17947929-01-0.  EPA project manager Edward Klappenbach, Great Lakes National Program Office, 77 West Jackson Boulevard, Chicago, IL  60604 (312) 353-1378.  

Please e-mail mark.stone@ndri.med.navy.mil for questions about this site. 


New Abstracts
Methylmercury Content of Dental-Unit Wastewater
TCLP Analysis and Residual Mercury Levels in Dental Wastewater Lines
New American Dental Association abstract evaluating amalgam separators
The Management of Mercury in the Dental-Unit Wastewater Stream  (Full paper in PDF Format)
Mercury Removal from Wastewater -- Dr. Thomas Klasson Oak Ridge National Laboratory
Solid Waste Disposal Issues and Dental Amalgam (Full paper in PDF Format)
  Residual Mercury Content and Leaching of Mercury and Silver from Used Amalgam Capsules (Full paper in PDF Format)
  The Removal of Mercury from Dental-Operatory Wastewater by Polymer Treatment
  Mercury Levels and Particle Size Distribution in the Dental Unit Wastewater Stream at Naval Dental Center, Norfolk, Virginia, USA
  Mercury Removal From Dental Operatory Wastewater Using Polymers
  Silver Generation Rates from Dental Wastewater
ICP Analysis of Dental Wastewater
  Electro Kinetic Properties of Colloidal Dental Wastewater
  Mercury Removal Method and Device for Dental Operatory Wastewater
  Mercury Management of Dental-Wastewater Streams Using Secondary Treatments
  Technique for Removing Polymer-Bound Mercury from Dental Wastewater
  Line Cleanser/Disinfectant Effects on Soluble Mercury Content of Dental Wastewater
  Mercury Removal from Dental Wastewater by a Microbial Bioadsorbent Derived from Genetically Engineered Bacteria
  Evaluation of an Integrated System to Remove Mercury from Dental-Unit Wastewater
  Mercury Hygiene Best Management Practices



Most of the mercury released into the wastewater stream leaving the dental-unit is in the form of amalgam particulate. However a significant quantity of mercury is in the "soluble form" (< 0.45 microns) and in high enough concentrations to violate discharge limits for some local Publicly Owned Treatment Works (POTWs). Amalgam separating devices currently marketed to remediate this problem are certified using an ISO standard (ISO 11143) that focuses on percent particle removal (> 95%) utilizing a standard amalgam sample suspended in water. However the regulations governing the discharge of metals into the wastewater stream are framed in terms of concentrations and load.  The United States Environmental Protection agency (US EPA) has instituted the Environmental Technology Verification Program (ETV) to verify the performance of commercial technologies.  The US EPA Office of Research and Development and NSF International, an independent, not-for-profit organization have published a protocol for the evaluation of amalgam separators.  This protocol looks at efficiency as a function of mercury concentrations  as opposed to percent particle removal. There are numerous "amalgam separating" devices available to dentists, but particle separation may not be enough to satisfy local regulators. Dentists need to be aware of this issue before purchasing expensive devices that may not satisfy the discharge requirements of POTWs.

Scanning electron micrograph of mercury containing amalgam particulate in dental-unit wastewater.

The following is a list of just a few of  the amalgam separating  systems (also known as pretreatment systems) available in the marketplace.  This list of commercially available products does not imply endorsement.

AB Dental Trends, Rasch 890 amalgam separator

KeyleX© mercury sorbent system from Solmetex, Inc.

ADA Technologies, Inc.

Nalco, Inc. polymers N8701 (NALMET®) and N8186 (ULTRION®)

Air Techniques, Inc

Maximum Separation Systems Inc.

Pure Water Development, L.L.C. - METASYS Group

Dental Amalgam Recyclers


Analytical Methods
Method 1630: is for determination of methyl mercury (CH3Hg) in filtered and unfiltered water by distillation, aqueous ethylation, purge and trap, desorption, and cold vapor atomic fluorescence spectrometry (CVAFS).
Method 1631: allows determination of mercury at a minimum level (ML) of 0.5 ng/L (parts-per-trillion; ppt), approximately 400 times lower than the level achieved by other mercury methods previously approved at 40 CFR Part 136.
Method 245.1: This method describes the instrumental analytical procedures for mercury by cold vapor atomic absorption (CVAA).
Method 7470 A: is a cold-vapor atomic absorption procedure approved for determining the concentration of mercury in mobility-procedure extracts, aqueous wastes, and ground waters.
Method 7471 A: is approved for measuring total mercury (organic and inorganic) in soils, sediments, bottom deposits, and sludge-type materials.
Method 7473: is designated for the determination of mercury in solids, aqueous samples, and digested solutions in both the laboratory and field environments


The following are links to other Websites that focus on the issues of mercury content from the dental-unit wastewater stream:
Agency for Toxic Substances and Disease Registry
Association of Metropolitan Sewerage Agencies (AMSA)
Great Lakes Information Network
Organization for Safety and Asepsis Procedures
The Great Lakes Regional Pollution Prevention Roundtable
The American Dental Association

Private Industry
Nalco Chemical Company
Solmetex, Inc.
ADA Technologies, Inc.

U.S. Military
Naval Dental Research Institute
US Air Force Dental Investigation Service
US Navy Dental Corps
Critical Issues Affecting the Naval Dental Corps

U.S. Legislation & Regulations
CESQGS Rule Page
CFR 40
Clean Air Act of 1970, as Amended
Clean Water Act of 1977, as Amended
RCRA Online
Rule 1179
Safe Drinking Water Act
Toxic Substances Control Act of 1976
U.S. EPA Programs/Documentation
United States Environmental Protection Agency (USEPA)
EPA's Office of Water Homepage
The Great Lakes National Program Office
Mercury In Medical Facilities
US EPA Protocol for testing and evaluation of amalgam separators


Environmental Health Perspectives Volume 107, Number 1, January 1999

[ Citation in PubMed ] [ Related Articles ]

The Removal of Mercury from Dental-operatory Wastewater by Polymer Treatment

Ernest D. Pederson, Mark E. Stone, and Victor G. Ovsey

Naval Dental Research Institute, Applied Laboratory Science Department, Great Lakes, IL 60088-5259 USA


The mercury (Hg) content of dental-operatory wastewater has become an issue in many localities, and Hg removal is rapidly becoming a matter of concern for all dental clinics. This preliminary study tested the efficacy of polymers for the removal of Hg contaminants from the dental-unit wastewater stream. Two commercially available polymers were used to treat dental-operatory wastewater. Used separately, each polymer removed from 74.9% to 88.4% of the Hg from dental-wastewater supernatant. The polymers used in combination, within the recommended pH range, removed up to 99.9% of the total Hg from dental-wastewater supernatant. The estimated optimal concentration of the two polymers is approximately 2.33 ml of each per liter of waste, and more than 90% of the Hg may be removed with 0.13 ml/l. Results indicate that a combination of the two polymers may sufficiently reduce Hg levels to allow discharge of clarified supernatants into public sewer systems. Key words: amalgam, dental, mercury, polymer, wastewater. Environ Health Perspect 107:3-8 (1999). [Online 4 December 1998]



Address correspondence to E.D. Pederson, Naval Dental Research Institute, Applied Laboratory Science Department, Building 1-H, 310A B Street, Great Lakes, IL 60088-5259 USA.

We thank B.L. Lamberts and P.L. Fan for assistance with manuscript preparation and P.L. Choo for providing the polymers. Supported by the Naval Medical Research and Development Command, Bethesda, Maryland, project 063706N M0095.006-0515. The views expressed herein are those of the authors and do not necessarily reflect the official policy or position of the Departments of the Navy or Defense, nor the U. S. Government. The use of commercially available products does not imply endorsement.

Received 28 April 1998; accepted 4 August 1998.



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