f>EPA
United States
Environmental Protection
Agency
Technical Fact Sheet -
Tungsten
September 2017
TECHNICAL FACT SHEET - TUNGSTEN
Introduction
This fact sheet, developed by the U. S. Environmental Protection Agency
(EPA) Federal Facilities Restoration and Reuse Office (FFRRO), provides a
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. This
fact sheet provides basic information on tungsten to site managers and other
field personnel who may address tungsten contamination at cleanup sites.
Historically, tungsten was thought to be insoluble and have little or no mobility
in the environment. However, the presence of tungsten in groundwater near
background sources and anthropogenic sources suggests that under certain
conditions, tungsten dissolves in water and is mobile in the environment.
Currently, limited information is available about the fate and transport 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 historic use in the defense industry as a
substitute for lead-based munitions.
What is tungsten?
Tungsten is a naturally occurring element that exists in the form of
minerals, but typically not as a pure metal (ATSDR 2005).
The color of tungsten may range from white for the pure metal to steel-
gray for the metal with impurities (NIOSH 2016).
There are more than 20 known tungsten-bearing minerals (ATSDR 2005).
Wolframite ([FeMn]W04) and Scheelite (CaW04) are two common,
commercially-mined minerals that contain tungsten (ATSDR 2005;
Koutsospyros and others 2006).
Natural tungsten is composed of five stable isotopes. There are 28
artificial radioactive isotopes, which have short half-lives ranging from less
than a second to 121 days (ATSDR 2005; Audi and others 2003).
The most common formal oxidation state of tungsten is +6, but it exhibits
all oxidation states from -2 to +6 (Lemus and Venezia 2015).
The melting point of tungsten is the highest among metals. It is resistant
to corrosion, is a good conductor of electricity and acts as a catalyst in
chemical reactions (ATSDR 2005; Gbaruko and Igwe 2007).
Disclaimer: The U.S. EPA prepared this fact sheet using the most recent publicly-
available scientific information; additional information can be obtained from the source
documents. This fact sheet is not intended to be used as a primary source of information
and is not intended, nor can it be relied upon, to create any rights enforceable by any
party in litigation with the United States. Mention of trade names or commercial products
does not constitute endorsement or recommendation for use.
At a Glance
~	Tungsten is a naturally
occurring element that exists
in the form of minerals, but
typically not as a pure metal.
~	Typically used in welding, oil-
drilling, electrical and
aerospace industries.
~	Introduced in the mid-1990s
as a replacement for lead
ammunitions.
~	Under certain conditions,
tungsten dissolves in water
and is mobile in the
environment, but little is
known about its fate and
transport in the environment.
~	In 2002, elevated tungsten
concentrations were found in
drinking water and
investigated for carcinogenic
effects. No direct link was
found, but tungsten was
nominated for study under
the National Toxicity
Program.
~	No federal drinking water
standard established.
~	2017 EPA regional screening
levels include soil and
tapwater screening values for
tungsten.
~	Treatment methods for
tungsten in environmental
media are currently under
development. Methods under
investigation include
electrokinetic soil remediation
and phytoremediation.
United States
Environmental Protection Agency
Land and Emergency
Management (5106P)
1
EPA 505-F-17-004
September 2017

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Technical Fact Sheet - Tungsten
~ Tungsten in the form of finely divided powder is highly flammable and may ignite spontaneously on contact
with air. Powdered tungsten may also cause fire or explosion on contact with oxidants (HSDB 2009; NIOSH
2016).
Exhibit 1: Physical and Chemical Properties of Elemental Tungsten
(ATSDR 2005; NIEHS 2003; NIOSH 2016)
Property
Value
Chemical Abstracts Service (CAS) number
7440-33-7
Physical description (physical state at room temperature)
Hard, steel-gray to tin-white solid
Molecular weight (g/mol)
183.85
Water solubility
Insoluble
Boiling point (C at 760 mm Hg)
5,900
Melting point (C)
3,410
Vapor pressure at 2,327C (mm Hg)
1.97 x 10"7
Specific gravity/Density at 20F /4C
18.7 to 19.3
Abbreviations: g/mol - grams per mole; C - degrees Celsius; mm Hg - millimeters of mercury.
Existence of tungsten in the environment
~	Tungsten-based products have been used in a
wide range of applications ranging from common
household products to highly specialized
components of science and technology
(Koutsospyros and others 2006).
~	Tungsten/nylon "green" bullets were introduced as
a replacement to lead bullets and other
ammunition in the United States in the 1990s. In
early 2003, the production of tungsten/nylon
bullets was discontinued based on flight instability
issues (USACE 2007).
~	Recent reports of tungsten contamination in
groundwater and soil at military sites have raised
concerns about tungsten's stability in the
environment and resulted in the suspension of
tungsten/nylon bullets in some military applications
(Kennedy and others 2012; USACE 2007).
~	Tungsten may be present in the environment as a
result of mining, weathering of rocks, burning of
coal and municipal solid waste, land application of
fertilizers or industrial applications (ATSDR 2005).
~	In the ambient atmosphere, tungsten compounds
exist in the particulate phase because of their low
vapor pressures. These particles may settle on
soil, water or other surfaces and can be mobilized
through rain or other forms of precipitation
(ATSDR 2005; NIEHS 2003).
~	Principal transport and transformation
mechanisms include deposition (wet and dry),
advective transport, colloidal transport, chemical
precipitation, oxidation/reduction, dissolution,
complexation, adsorption and anion exchange
(Koutsospyros and others 2006).
~	Studies indicate that an elevated pH in soil may
increase the solubility of tungsten and cause it to
leach more readily into the groundwater table
(ASTSWMO 2011).
~	Laboratory studies found that the dissolution of
tungsten into tungstate ions was accompanied by
significant reductions in pH and dissolved oxygen
concentrations (ASTSWMO 2011).
~	Studies found large amounts of dissolved tungsten
when tungsten powder or alloy pieces were
exposed to aqueous solutions. Additionally,
tungsten appears to undergo strong uptake by
clay minerals and organic soils (Dermatas and
others 2004).
~	Increased acidification and oxygen depletion of
soils from dissolution of tungsten powder have
been shown to trigger changes in the soil microbial
community, causing an increase in fungal biomass
and a decrease in the bacterial component
(Dermatas and others 2004; Strigul and others
2005).
~	Water soluble tungsten substances include
sodium tungstate, ammonium metatungstate,
sodium metatungstate and ammonium
paratungstate. Insoluble tungsten substances
include tungsten metal, tungsten carbide,
ditungsten carbide, tungsten trioxide, tungsten
oxides and tungsten disulfide (Lemus and Venezia
2015).
~	Studies suggest that the tungsten powder used in
the Army's tungsten/nylon bullets forms oxide
coatings that dissolve in water and may be mobile
under some environmental conditions. (Kennedy
and others 2012; USACE 2007).
~	Plants are known to take up and accumulate
tungsten in substantial amounts and plant toxicity
has been reported in the literature (Koutsospyros
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Technical Fact Sheet - Tungsten
and others 2006; Kennedy and others 2012;
Adamakis and others 2008).
~	Tungsten anions polymerize in environmental
systems and under physiological conditions in
living organisms. These reactions result in the
development of several types of polyoxoanions
that differ from monotungstates in certain chemical
properties (Strigul 2010).
~	Recent studies indicate that tungsten speciation
may be important to ecotoxicology. Polytungstates
What are the routes of exposure and
tungsten?	
~	Tungsten bioaccumulates in the liver of mammals
(Kennedy and others 2012).
~	Recent studies found evidence for
bioaccumulation of tungsten in plants from soil,
implying the potential for trophic transfer into the
terrestrial food web (Kennedy and others 2012).
~	Results from a bioaccumulation study conducted
using cabbage and snails showed tungsten
compartmentalized first in the hepatopancreas,
following by the body and foot. The results also
suggested snails consuming contaminated
cabbage accumulated higher tungsten
concentrations relative to the concentrations
directly bioaccumulated from dermal exposure to
soil (Kennedy and others 2012).
~	A study conducted using male mice exposure to
sodium tungstate in tapwater reported dose-
dependent increases in tungsten concentration in
bone and bone marrow (ATSDR 2015).
~	Studies on mice have shown that exposure to
sodium tungstate resulted in effects on the
immune system and tungsten-related immune
suppression (ATSDR 2015).
~	Studies on female rats have shown that exposure
to tungsten caused post-implantation deaths and
developmental abnormalities in the
musculoskeletal system (NIEHS 2003); pre and
postnatal exposure to sodium tungstate may
produce subtle neurobehavioral effects related to
motor activity and emotionality in offspring
(Mclnturf and others 2011); and tungsten primarily
accumulated in bones and in the spleen after oral
exposure (NIEHS 2003).
~	Exposure to tungsten in large amounts may cause
breathing problems and changes in behavior
(ATSDR 2005, 2015; Lemus and Venezia 2015).
develop and persist in environmental systems and
are much more toxic than monotungstates. For
example, sodium metatungstate, a polytungstate,
is significantly more toxic to fish than sodium
tungstate, a monotungstate (Strigul 2010).
~ As of 2016, tungsten has been identified at one
site on the EPA National Priorities List (NPL) (EPA
2016a).
the potential health effects of
~	Symptoms of tungsten exposure can include
irritation of the eyes, skin and respiratory system,
diffuse pulmonary fibrosis, loss of appetite,
nausea, cough and blood changes (NIOSH 2016).
~	The EPA's Toxic Substances Control Act (TSCA)
Interagency Testing Committee has included
tungsten compounds in the Priority Testing List,
which is a list of chemicals regulated by TSCA for
which there are suspicions of toxicity or exposure
and for which there are few, if any, ecological
effects, environmental fate or health effects testing
data (EPA 2006).
~	The occurrence of a cluster of childhood leukemia
cases in Fallon, Nevada prompted a wide
investigation that included several local, state and
federal agencies led by the Centers for Disease
Control and Prevention (CDC). Groundwater was
a source of drinking water and was found to have
naturally elevated tungsten concentrations.
Although no direct link was found, in 2002,
tungsten was nominated for study under the
National Toxicology Program (NIEHS 2003). In
2011 it was nominated for human health risk
assessment under the EPA's Integrated Risk
Information System (IRIS) agenda (EPA 2016b).
~	In 2005, the ATDSR issued its toxicological profile
for tungsten, identifying several data gaps in
toxicity and exposure pathways. In 2015, ATSDR
published an addendum to the toxicological profile
for tungsten (ATSDR 2015). Additional laboratory
studies were described for tungsten and its related
substances in the addendum, but the conclusion
did not change from 2005 to 2015. Available data
are insufficient for derivation of a Minimum Risk
Level (ATSDR 2015).
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Technical Fact Sheet - Tungsten
Are there any federal and state guidelines and health standards for
tungsten?
A federal drinking water standard has not been
established for tungsten. In addition, EPA has not
derived a chronic inhalation reference
concentration (RfC) or a chronic oral reference
dose (RfD) for tungsten or tungsten compounds
(EPA 2016c, d).
EPA's regional screening levels include soil and
tapwater screening values for tungsten due to
Provisional Peer Reviewed Toxicity Values for
Superfund (EPA 2017).
Three states have standards for tungsten. Indiana
is the only state that has soil and groundwater
screening levels (IDEM 2016). North Carolina has
preliminary soil remediation goals for tungsten
(NCDEQ 2016). Texas has soil and groundwater
protective concentration levels for sodium
tungstate dihydride (TCEQ 2016).
What detection and site characterization methods are available for
tungsten?
Tungsten analysis is still in the development and
optimization stage. For screening purposes, x-ray
fluorescence seems to be the most common type
of equipment used (ASTSWMO 2011).
NIOSH Method 7074 is the preferred method for
analysis (ASTSWMO 2011). It uses flame atomic
absorption to detect tungsten in air. It has a
detection limit of 0.25 mg (milligrams) for insoluble
forms of tungsten and 0.1 mg for soluble forms of
tungsten (NIOSH 1994).
Other NIOSH methods for the detection of
tungsten in air are Methods 7300 and 7301,
involving inductively coupled argon plasma-atomic
emission spectroscopy. The working range for
these methods is 0.005 to 2.0 mg/m3for each
element in a 500-liter air sample. Special sample
treatment may be required for some tungsten
compounds (NIOSH 2003a, b).
OSHA Method ID-213 is also used for the
detection of tungsten in air. The method uses
inductively coupled plasma (ICP)-atomic emission
spectroscopy (AES) and has a quantitative
detection limit of 0.34 mg/m3 (OSHA 1994).
Tungsten in soil and water can be measured using
the I CP-AES, I CP-mass spectrometry (I CP-MS),
neutron activation analysis (NAA),
ultraviolet/visible spectroscopy (UV/VIS) methods
(ATSDR 2005). EPA SW-846 Methods 6010 and
6020 may be modified for the detection of
tungsten in soil and water (ASTSWMO 2011).
The microwave-assisted acid digestion SW-846
Method 3051A can be modified to enhance
tungsten recovery from soils (Griggs and others
2009).
Tungstate can be measured and mapped in
waters, soils and sediments using the low-
disturbance diffusive gradient in thin-films passive
sampling technique (Guan and others 2016).
What technologies are being used to treat tungsten?
Preliminary studies indicate that phytoremediation
may be a potential treatment method for tungsten-
contaminated sites based on the reported
accumulation of tungsten in plant tissue (Strigul
and others 2005; Tuna and others 2012; Erdemir
and others 2016).
Electrokinetic soil remediation is an emerging in
situ technology for removal of tungsten from low-
permeability soils in the presence of heavy metals
such as copper and lead. A direct current is
applied to contaminated soils using electrodes
inserted into the ground (Braida and others 2007).
Studies have reported the efficient removal (98 to
99 percent) of tungsten from industrial wastewater
by precipitation, coagulation and flocculation
processes using ferric chloride under acidic
conditions (pH below 6) (Plattes and others 2007).
A recent study reported 98 percent removal of
tungsten from industrial wastewater using acid-
and heat-treated sepiolite (Wang and others
2015).
A recent study demonstrated the efficient recovery
of tungsten (over 90 percent) in aqueous solutions
using a water-soluble polymer (polyquaternium-6)
for complexing anion forms of tungsten prior to
ultrafiltration (Zeng and others 2012).
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Technical Fact Sheet - Tungsten
Where can I find more information about tungsten?
~	Adamakis, I.D.S., Eleftheriou, E., aridT. Root.
2008. "Effects of sodium tungstate on the
ultrastructure arid growth of pea (pisum sativum)
arid cotton (Gossypium hirsutum) seedlings."
Environmental and Experimental Botany. Volume
63. Pages 416 to 425.
~	Agency for Toxic Substances and Disease
Registry (ATSDR). 2005. "Toxicological Profile for
Tungsten."
www.atsdr.cdc.aov/toxprofiles/tp186. pdf
~	ATSDR 2015. "Addendum to the Toxicological
Profile for Tungsten."
www.atsdr.cdc.qov/toxprofiles/Tunasten Addendu
m 508.pdf
~	Association of State and Territorial Solid Waste
Management Officials (ASTSWMO). 2011.
"Tungsten Issues Paper." www.astswmo.org/
Files/Poiicies and Publications/Federal Facilities/
2011-02 FINAL Tungsten Issues 2-0.pdf
~	Audi, G., Bersillon, O., Blachot, J., and A.H.
Wapstra. 2003. "The NUBASE evaluation of
nuclear and decay properties." Nuclear Physics.
Volume A 729. Pages 3 to 128.
~	Braida, W., Christodoulatos, C., Ogundipe, A.,
Dermatas, D., and G. O'Connor. 2007.
"Electrokinetic Treatment of Firing Ranges
Containing Tungsten-Contaminated Soils." Journal
of Hazardous Materials. Volume 149. Pages 562
to 567.
www.sciencedirect.com/science/article/pii/S03043
89407009612
~	Dermatas, D., Braida, W., Christodoulatos, C.,
Strigul, N., Panikov, N., Los, M., and S. Larson.
2004. "Solubility, Sorption, and Soil Respiration
Effects of Tungsten and Tungsten Alloys."
Environmental Forensic. Volume 5. Pages 5 to 13.
~	Erdemir, U.S., Arslan, H., Guleryuz, G., and S.
Gucer. 2016. "Elemental Composition of Plant
Species from an Abandoned Tungsten Mining
Area: Are They Useful for Biogeochemical
Exploration and/or Phytoremediation Purposes?"
Bulletin of Environmental Contamination and
Toxicology. Pages 1 to 5.
~	Gbaruko, B.C., and J.C. Igwe. 2007. "Tungsten:
Occurrence, Chemistry, Environmental and Health
Exposure Issues." Global Journal of
Environmental Research. Volume 1 (1). Pages 27
to 32.
~	Griggs C., Larson, S., Nestler, C., and M.
Thompson. 2009. "Coupling of Oxygen and pH
Requirements for Effective Microwave-Assisted
Digestion of Soils for Tungsten Analysis." Land
Contamination & Reclamation. Volume 17. Pages
121 to 128.
Guan, D.X., Williams, P.N., Xu, H.C., Li, G., Luo,
J., and L.Q. Ma. 2016. "High-resolution
measurement and mapping of tungstate in waters,
soils, and sediments using the low-disturbance
DGT sampling technique. Journal of Hazardous
Materials. Volume 316. Pages 69 to 76.
Hazardous Substances Data Bank (HSDB). 2009.
Elemental Tungsten. toxnet. nlm. nih.gov/coi-
bin/sis/htmlqen?HSDB
Indiana Department of Environmental
Management (IDEM). 2016. "Remediation Closure
Guide, Appendix A".
www.in.gov/idem/landguaiitv/fiies/risc screening t
able 2016.pdf
Kennedy, A.J., Johnson, D.R., Seiter, J.M,
Lindsay, J.H., Boyd, R.E., Bednar, A.J., and P.G.
Allison. 2012. "Tungsten Toxicity,
Bioaccumulation, and Compartmentaiization into
Organisms Representing Two Trophic Levels."
Environmental Science and Technology. Volume
46 (17). Pages 9646 to 9652.
Koutsospyros, A., Braida, W., Christodoulatos, C.,
Dermatas, D., and N. Strigul. 2006. "A Review of
Tungsten: From Environmental Obscurity to
Scrutiny." Journal of Hazardous Materials. Volume
136. Pages 1 to 19.
Lemus, R., and C.F. Venezia. 2015. "An update to
the toxicological profile for water-soluble and
sparingly soluble tungsten substances." Critical
Reviews in Toxicology. Volume 24 (5). Pages 388
to 411.
Mclnturf, S.M., Bekkedal, M.Y.V., Wilfong, E.,
Arfsten, D., Chapman, G., and P.G. Gunasekar.
2011. The potential reproductive, neurobehavioral
and systemic effects of soluble tungstate exposure
in Sprague-Dawley rats. Toxicology and Applied
Pharmacology. Volume 254 (2). Pages 133 to 137.
National Institute of Environmental Health
Sciences (NIEHS). 2003. "Tungsten and Selected
Tungsten Compounds - Review of Toxicological
Literature." ntp.niehs.nih.gov/ntp/htdocs/
Chem Background/ExSumPdf/tungsten 508.pdf
National Institute for Occupational Safety and
Health (NIOSH). 1994. "Tungsten (Soluble and
Insoluble) - Method 7074." NIOSH Manual of
Analytical Methods (NMAM), Fourth Edition.
www.cdc.gov/niosh/docs/2003-154/pdfs/7074. pdf
NIOSH. 2003a. "Elements by I CP (Nitric/Perchloric
Acid Ashing) - Method 7300." NIOSH Manual of
Analytical Methods (NMAM), Fourth Edition.
www.cdc.gov/niosh/docs/2003-154/pdfs/7300. pdf
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Technical Fact Sheet - Tungsten
Where can I find more information about tungsten? (continued)
~	NIOSH. 2003b. "Elements by I CP (Aqua Regia
Ashing) - Method 7301." NIOSH Manual of
Analytical Methods (NMAM), Fourth Edition.
www, cdc. aov/niosh/docs/2003-
154/pdfs/7301.pdf
~	NIOSH. 2016. NIOSH Pocket Guide to Chemical
Hazards: Tungsten.
www.cdc.aov/niosh/npg/npad0645.html
~	North Carolina Department of Environmental
Quality (NCDEQ). 2016. "Preliminary Soil
Remediation Goals (PSRG) Table."
ncdenr.s3.amazonaws.com/s3fs-
pubiic/Waste%20Manaaement/DWM/SF/IHS/gui
dance/SoilTable%20APRIL%202016%20-Final-
1 ocb1. pdf
~	Occupational Safety and Health Administration
(OSHA). 1994. "Tungsten and Cobalt in
Workplace Atmospheres (ICP Analysis)."
www.osha.gov/dts/sltc/methods/inoraanic/id213/i
d213.html
~	Plattes, M., Bertrand, A., Schmitt, B., Sinner, J.,
Verstraeten, F., and J. Welfring. 2007. "Removal
of Tungsten Oxyanions from Industrial
Wastewater by Precipitation, Coagulation and
Flocculation Processes." Journal of Hazardous
Materials. Volume 148 (3). Pages 613 to 615.
~	Strigul, N., Koutsospyros, A., Arienti, P.,
Christodoulatos, C., Dermatas, D., and W.
Braida. 2005. "Effects of Tungsten on
Environmental Systems." Chemosphere.
Volume 61. Pages 248 to 258.
~	Strigul, N. 2010. "Does speciation matter for
tungsten ecotoxicology?" Ecotoxicology and
Environmental Safety. Volume 73. Pages 1099
to 1113.
~	Texas Commission on Environmental Quality
(TCEQ). 2016. "Texas Risk Reduction Program
Protective Concentration Levels."
www.tceq.texas.gov/assets/public/remediation/tr
rp/pcls.pdf
Contact Information
Tuna, G.S., Braida, W., Ogundipe, A., and D.
Strickland. 2012. "Assessing Tungsten
Transport in the Vadose Zone: From Dissolution
Studies to Soil Columns." Chemosphere.
Volume 86 (12). Pages 1001 to 1007.
U.S. Army Corps of Engineers (USACE). 2007.
"Fate and Transport of Tungsten at Camp
Edwards Small Arms Ranges." ERDC TR-07-5.
www.dtic.mil/cai-
bin/GetTRDoc?Location=U2&doc=GetTRDoc.pd
f&AD=AD A471941
EPA. 2006. "Fifty-Eighth Report of the TSCA
Interagency Testing Committee to the
Administrator of the Environmental Protection
Agency; Receipt of Report and Request for
Comments; Notice." Federal Register. Volume
71 (132). Page 39187.
EPA. 2016a. Superfund Information Systems.
Superfund Site Information.
cumulis.epa.gov/supercpad/cursites/srchsites.cf
HI
EPA 2016b. Integrated Risk Information System
(IRIS), www.epa.gov/iris
EPA. 2016c. Drinking Water Contaminants.
water .e pa. gov/drink/contaminants/index.cfm#Lis
t
EPA 2017. Regional Screening Levels.
www.epa.gov/risk/regional-screenina-levels-rsls
Wang, Y., Chen, K., Mo, L., Li, J., and J. Xu.
2015. "Removal of tungsten from electroplating
wastewater by acid- and heat-treated sepiolite."
Desalination and Water Treatment. Volume 56
(1). Pages 232 to 238.
Zeng, J., Sun, X., Zheng, L., He, Q., and S. Li.
2012. "Recovery of Tungsten (VI) from Aqueous
Solutions by Complexation-Ultrafiltration
Process with the Help of Polyquaternium."
Chinese Journal of Chemical Engineering.
Volume 20 (5). Pages 831 to 836.
If you have any questions or comments on this fact sheet, please contact: Mary Cooke, FFRRO at
cooke. marvt@epa.aov.
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