Emerging  Contaminant - Tungsten
                                                                              April 2008
                                                                                       FACT SHEET
At a  Glance
                                      Introduction
    Hard, steel-gray to tin-white solid.
    Highest melting point among metals.
    Highly flammable and may cause fire
    or explosion when exposed to
    oxidants.
    Low solubility in water and high
    sorption (soil/water distribution)
    coefficients at low to neutral pH levels.
    Typically used in welding, oil-drilling,
    electrical, and aerospace industries.
    Currently  used in "Green Bullets" as
    an environmentally friendly alternative
    to conventional lead-based
    ammunition.
    Exposure may cause eye and skin
    irritation, cough, nausea, diffuse
    Interstitial pulmonary fibrosis, and
    changes in blood.
    Has not been classified for
    carcinogenic effects.
    Exposure limits set by the National
    Institute for Occupational Safety and
    Health  (NIOSH) and the American
    Conference of Governmental Industrial
    Hygienists(ACGIH).
    No federal drinking water standard has
    been established.
    Treatment methods for tungsten in
    environmental media are currently
    under development.  Methods under
    investigation involve ice-electrodes,
    chemical recovery/soil washing, and
    phytoremediation.
An "emerging contaminant" is a chemical or material that is
characterized by a perceived, potential, or real threat to human health or
the environment or a lack of published health standards. A contaminant
may also be "emerging" because a new source or a new pathway to
humans has been discovered or a new detection method or treatment
technology has been developed (DoD 2007). This fact sheet, developed
by the U.S. Environmental Protection Agency (EPA) Federal Facilities
Restoration and Reuse Office (FFRRO), provides a brief summary for
tungsten, including: physical and chemical properties; environmental
and health impacts; existing federal and state guidelines; detection and
treatment methods; and additional sources of information.

Tungsten was originally considered a metal that remains stable in soil
and does not dissolve easily in water.  However, it is now a growing
concern to the EPA and Department of Defense (DoD) because recent
research indicates that tungsten may not be as stable as was indicated
in earlier studies. Furthermore, varying soil properties such as pH may
cause tungsten to dissolve and leach into the underlying aquifer (ATSDR
2005).  Currently, little information is available about the fate of tungsten
in the environment and its effects on human health. Research about
tungsten is ongoing and includes health effects and risks, degradation
processes, and an inventory of its use in the defense industry as a
substitute for lead-based munitions. This fact sheet provides basic
information on tungsten to site managers and other field personnel who
may be faced with  tungsten contamination at a cleanup site.

What is tungsten?	

*  Tungsten (also known as Wolfram and represented by the letter W
   in the periodic table) is a naturally occurring element that exists in
   the form of minerals or other compounds but typically not as a pure
   metal (NIOSH  2005; ATSDR 2005).
*  Wolframite ([FeMn]WO4), and Scheelite (CaWO4) are two common
   minerals that contain tungsten (Werner and others 1998).

*  Based on its purity, the color of tungsten may range from white for
   the pure metal to steel-gray for the metal with impurities. It is
   commercially available in powdered or solid form (ATSDR 2005;
   NIOSH 2005; NIOSH 2007).

*  The melting point of tungsten is the highest among metals and it
   resists corrosion.  It is a good conductor of electricity and acts as a
   catalyst in chemical reactions (ATSDR 2005; Massachusetts DEP
   2006; Werner and others 1998).
  United States
  Environmental Protection
  Agency
       Solid Waste and
       Emergency Response
       (5106P)

             1
EPA 505-F-07-005
       April 2008

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What is tungsten (continued)?
    Tungsten ore is used primarily to produce
    tungsten carbide and tungsten alloys, which are
    used in many general welding and metal-cutting
    applications, in making drilling equipment for oil
    wells, and in operations within the aerospace
    industry. Tungsten metal is also used to
produce lamp filaments, X-ray tubes, dyes, and
paints for fabrics (ATSDR 2005; Werner and
others 1998).
The DoD has used tungsten as a replacement
for lead in bullets and other ammunition since
1999 (Massachusetts National Guard 2006).
What are the environmental impacts of tungsten?
    Tungsten is a common contaminant at industrial
    sites that use tungsten and at DoD sites
    involved in the manufacture, storage, and use of
    tungsten-based ammunition (DoD 2007).
    Tungsten particles may be present in air as a
    result of mining, weathering of rocks, or
    industrial applications that involve tungsten.
    These particles may settle on soil, water, or
    other surfaces and can be deposited through
    rain or other forms of precipitation (ATSDR
    2005; Massachusetts DEP 2006).
    Tungsten powder is highly flammable and may
    ignite instantly on contact with air (ATSDR 2005;
    NJDEP 2000). Tungsten also may cause fire or
    explosion on contact with oxidants (NIOSH
    2007).
    Tungsten has been detected at six National
    Priorities List (NPL) sites (ATSDR 2005).
    Earlier research on tungsten indicated that it is
    stable in soil because of its soil binding capacity
    and its insolubility in water. At lower pH values,
    sorption coefficients increase,  indicating lower
    mobility of tungsten. Recent studies indicate
    that an elevated pH level in soil at a site may
    increase the solubility of tungsten by decreasing
    its sorption coefficient, which may cause it to
leach more readily into the groundwater table.
(ATSDR 2005; NIEHS 2003; TOXNET 2007;
Warminsky and Larson 2004).
In 1997, EPA Region  1 issued administrative
orders to suspend the use of lead bullets at the
Massachusetts Military Reservation (MMR).
Small arms training at MMR continued
uninterrupted using tungsten nylon bullets.
However, the stability of tungsten in the
environment became questionable when
tungsten was detected in the groundwater and
above baseline levels in soil at a
small arms range at MMR in 2006, resulting in
the suspension of the  use of the tungsten nylon
bullets at MMR (EPA 2007; ATSDR 2005;
Massachusetts National Guard 2006).
Under the  U.S. Army's Green Bullet program,
nearly 88 million bullets were produced, of which
33 million remain unfired and available for use at
training ranges across the country.  Currently,
the Army Environmental Center is looking at
training ranges to evaluate the presence of
various chemicals and other potential
contaminants, including tungsten (Defense
Environmental Alert 2007).
                       Exhibit 1: Physical and Chemical Properties of Tungsten
                               (NIOSH 2005; NIEHS 2003; TOXNET 2007)
Property
CAS Number
Physical Description (Physical state at room temperature)
Molecular weight (g/mol)
Water solubility (g/L at 25°C)
Boiling point (°C)
Melting point (°C)
Vapor pressure at 25°C (mm Hg)
Specific gravity

7440-33-7
Hard, steel-gray to tin-white solid
183.9
Insoluble at pH less than 6.5
5,927
3,410
0
19.3
      Notes:  g/mol - gram per mole; g/L - grams per liter; °C - degrees Celsius; mm Hg - millimeters of mercury.

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What are the health effects of tungsten?
    Occupational exposure is considered the most
    common scenario for human exposure to
    tungsten and its compounds.  Inhalation,
    ingestion, and dermal and eye contact are the
    possible exposure pathways (ATSDR 2005;
    NIOSH 2007).
    Occupational inhalation exposure to tungsten is
    known to affect the eyes, skin, respiratory
    system, and blood (ATSDR 2005).  Tungsten
    may cause  irritation to eyes, skin and throat;
    diffuse interstitial pulmonary fibrosis; loss of
    appetite; nausea; cough; and changes in the
    blood (NIOSH 2005).
Tungsten has not been classified for
carcinogenic effects by the Department of
Health and Human Services (DHHS), the
International Agency for Research  on Cancer
(IARC), or EPA (ATSDR 2005).
Studies on rats have shown that oral exposure
to tungsten caused post-implantation deaths and
developmental abnormalities in the
musculoskeletal system.  Exposure of pregnant
rats to sodium tungstate resulted in fetal death
(NIEHS2003).
Are there any existing federal and state guidelines and health standards for
tungsten?
   A federal drinking water standard has not been
   established for tungsten.
   The National Institute for Occupational Safety
   and Health (NIOSH) and the American
   Conference of Industrial Hygienists (ACGIH)
   have established a recommended exposure limit
   (REL) of 5 milligrams per cubic meter (mg/m3)
   as the time-weighted average (TWA) over a 10-
   hour work exposure and 10 mg/m3 as the 15-
minute, short-term exposure limit (STEL) for
airborne exposure to tungsten (ATSDR 2005;
NIOSH 2007; NJDEP 2000).
The Occupational Safety and Health
Administration (OSHA) recommends an
exposure limit of 5 mg/m3 to insoluble
compounds of tungsten and a 1  mg/m3 limit of
exposure to soluble compounds in construction
and shipyard industries (ATSDR 2005).
What detection and site characterization methods are available for tungsten?
    NIOSH Method 7074 - flame atomic absorption
    spectroscopy with a detection limit of 0.1 mg/m3
    for insoluble forms of tungsten and 0.05 mg/m3
    for soluble forms of tungsten  in air (NIOSH
    2005; TOXNET 2007).
    Other NIOSH methods known to be used for
    tungsten are Methods 7300 and 7301.
    Information about detection limits for these
    methods is not available in the references cited
    (NIOSH 2005; TOXNET 2007).
OSHA ID213 - inductively coupled plasma
atomic emission spectroscopy (ICP-AES) with a
detection limit of 0.34 mg/m  for tungsten in air
(NIOSH 2005; OSHA 2007).
Tungsten in soil and water can be measured
using the ICP-AES, ICP-mass spectrometry
(ICP-MS), and ultraviolet/visible spectroscopy
(UV/VIS) methods (ATSDR 2005).
What technologies are being used to treat tungsten?
   Treatment technologies to address tungsten
   contamination in environmental media are
   currently under development. According to
   preliminary studies conducted by various
   research groups, potential treatment methods
   involve chemical recovery/soil washing and
   phytoremediation (Lehr2004; Warminsky and
   Larson 2004).
"Ice electrode" is an innovative technology being
evaluated for liquid media. This technology is
based on the conventional electroplating
technique and uses an electrode coated with  a
thin layer of ice.  Tungsten ions adhere to the
ice-coated electrode and can be removed by
melting the ice (Lehr2004).

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Where can I find more information about tungsten?
   Agency for Toxic Substances and Disease
   Registry (ATSDR).  2005. Toxicological Profile
   for Tungsten.
   http://www.atsdr.cdc.gov/toxprofiles/tp186.pdf
   Hazardous Substances Data Bank:  Tungsten
   Compounds,  http://toxnet.nlm.nih.gov/cgi-
   bin/sis/search/r?dbs+hsdb:@term+@na+tungste
   n+compounds.
   Inside EPA.  2007.  Defense Environment Alert
   - Emerging Contaminants: Army risk study on
   tungsten could be first step toward regulation.
   January 23, 2007.
   Lehr, Jay H.  2004.  Wiley's Remediation
   Technologies Handbook: Major Contaminant
   Chemicals and Chemical Groups (ISBN 0-471-
   45599-7), pp. 282, 567, & 568.
   Massachusetts Department of Environmental
   Protection (DEP). 2006. Fact Sheet: Tungsten
   and Tungsten Compounds.
   Massachusetts National Guard. 2006.
   Massachusetts National Guard Temporarily
   Suspends Use of Tungsten-Nylon Ammunition
   at Camp Edwards, Massachusetts - News
   Release. .
   National Institute for Occupational Safety and
   Health (NIOSH). 2005.  NIOSH Pocket Guide to
   Chemical Hazards:  Tungsten.
   National Institute of Environmental Health
   Sciences (NIEHS).  2003. Tungsten and
   Selected Tungsten Compounds - review of
   Toxicological Literature.
   National Institute for Occupational Safety and
   Health (NIOSH). 2007.
   www.cdc.gov/niosh/ipcsneng/neng1404.html.
New Jersey Department of Health and Senior
Services. 2000. Hazardous Substance Fact
Sheet:  Tungsten.
http://ni.gov/health/eoh/rtkweb/documents/fs/195
9.pdf
Occupational Safety and Health Administration
(OSHA). 2007. Tungsten and Cobalt in
Workplace Atmospheres (ICP Analysis).
U.S. Department of Defense. 2007.  Emerging
Contaminants.
www.denix.osd.mil/denix/Public/Library/MERIT/
merit.html.
U.S. Environmental Protection Agency Region 1.
2007.  Massachusetts Military Reservation.
www.epa.gov/region01/mmr/.
Warminsky, Michael F. (AMEC Earth and
Environmental, Inc., Somerset, NJ) and Dr.
Steven Larson (U.S. Army Engineer Research
and Development Center, Vicksburg, MS).
Recovery and Recycling of Tungsten and Lead
from Small Arms Firing Range Soils. 2004.
Presented at the Annual Conference on Soil,
Sediment,  and Water- University of
Massachusetts Fall Conference (October 19-
21).
www.umasssoils.com/abstracts2004/Tuesday/tr
ainingranges.htm.
Werner, Antony B.T., W. David Sinclair, and
Earle B. Amey (USGS). 1998. International
Strategic Mineral Issues Summary Report—
Tungsten;  USGS Circular 930-O.
http://pubs.usgs.gov/pdf/circular/c930-o.pdf
Contact Information
If you have any questions or comments on this fact sheet, please contact:  Mary Cooke, FFRRO, by phone at
(703) 603-8712 or by e-mail at cooke.maryt@epa.gov.

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