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 firstname.lastname@example.org
for questions about this site.
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
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.
Dental Trends, Rasch 890 amalgam separator
mercury sorbent system from Solmetex, Inc.
Inc. polymers N8701 (NALMET®) and N8186 (ULTRION®)
Separation Systems Inc.
Water Development, L.L.C. - METASYS Group
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).
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
245.1: This method
describes the instrumental analytical procedures for
mercury by cold vapor atomic absorption (CVAA).
7470 A: is a
cold-vapor atomic absorption procedure approved for
determining the concentration of mercury in
mobility-procedure extracts, aqueous wastes, and
7471 A: is approved
for measuring total mercury (organic and inorganic)
in soils, sediments, bottom deposits, and
7473: is designated
for the determination of mercury in solids, aqueous
samples, and digested solutions in both the
laboratory and field environments
Health Perspectives Volume 107, Number 1, January 1999
in PubMed ] [ Related
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
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]
correspondence to E.D. Pederson, Naval Dental Research
Institute, Applied Laboratory Science Department,
Building 1-H, 310A B Street, Great Lakes, IL 60088-5259
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.