September 2003 |
ToxFAQs™ |
for |
Tungsten |
(Tungsteno) |
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This fact sheet answers the most frequently
asked health questions about Tungsten. For more information,
you may call the ATSDR Information Center at 1-888-422-8737.
This fact sheet is one in a series of summaries about hazardous
substances and their health effects. This information is important
because this substance may harm you. The effects of exposure
to any hazardous substance depend on the dose, the duration,
how you are exposed, personal traits and habits, and whether
other chemicals are present.
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HIGHLIGHTS: Tungsten is a naturally
occurring element. Exposure to very low levels of tungsten
may occur by breathing air, eating food, or drinking water
that contains tungsten. No specific health effects have
been associated with exposure to tungsten in humans. Exposure
to high levels of tungsten is unlikely. Tungsten has been
found in at least 6 of the 1,636 National Priority List
sites identified by the Environmental Protection Agency
(EPA). |
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What
is tungsten? |
Tungsten is a naturally occurring element.
It occurs in rocks and minerals combined with other chemicals,
but never as a pure metal. Elemental tungsten is a white to
steel gray metal (depending on the purity) that can be used
in pure form or mixed with other metals to make alloys. Tungsten
alloys tend to be strong and flexible, resist wear, and conduct
electricity well. Tungsten and its alloys are used as light
bulb filaments, as part of X-ray tubes, as a catalyst to speed
up chemical reactions, as a component of high-speed tools,
as welding electrodes, as gyroscope wheels, in bullets, and
in armor penetrators.
Chemical compounds of tungsten are used
for many purposes. Cemented tungsten carbide is a hard substance
used to make grinding wheels and cutting or forming tools.
Other tungsten compounds are used in ceramic pigments, as
fire retardant coatings for fabrics, and as color-resistant
dyes for fabrics.
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What
happens to tungsten when it enters the environment? |
- Tungsten minerals occur naturally in the environment.
- The element tungsten cannot be destroyed in nature, it
can only change forms.
- Fine tungsten particles are released to the air by weathering.
Emissions from hard metal industry also increase tungsten
levels in air. Particles in the air fall out onto surface
water, plant surfaces, and soil either by themselves or
when it rains or snows.
- Water is not normally tested for tungsten. Tungsten in
water comes mainly from the dissolution of tungsten from
rocks and soil that water runs over and through.
- Tungsten in water may be in either soluble or insoluble
forms. Insoluble forms can settle to the bottom where tungsten
enters sediment.
- Disposal of coal ash, incinerator ash, and industrial
waste may increase the amount of tungsten in soil. Part
of tungsten in soil will remain bound and will not reach
groundwater.
- In the environment, water-soluble tungsten compounds can
change into water-insoluble tungsten compounds and vice
versa.
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How
might I be exposed to tungsten? |
- You can be exposed to very low levels of tungsten by breathing
air, eating food, or drinking water that contains tungsten.
Urban air generally contains more tungsten than rural air.
- Air normally contains less than 0.5 nanograms of tungsten
per cubic meter (a nanogram is 1 billionth of a gram).
- In general, exposure to tungsten from air, drinking water,
and food is expected to be very small.
- Occupational exposure to higher than background tungsten
metal may occur if you use tungsten metal or are engaged
in the machining of these metals. Occupational exposure
to tungsten carbide occurs during the machining of tungsten
carbide tools in the manufacturing process.
- Tungsten metal and metal alloys occur in consumer products
such as electronics, light bulb filaments, cemented tungsten
carbide grinding wheels, carbide tipped tools, and "green
bullets."
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How
can tungsten affect my health? |
Tungsten compounds have caused breathing
problems and changed behavior in some animals given large
amounts of tungsten compounds. However, you are not likely
to be exposed to amounts of tungsten in the air you breathe
or the food or water you take into your body that would be
large enough to cause similar effects.
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How
likely is tungsten to cause cancer? |
Studies to date have found no causal
relationship between exposure to tungsten and cancer in humans.
A limited number of cancer studies in animals did not provide
any evidence of carcinogenicity for tungsten. However, tungsten
has been recommended to the National Toxicology Program (NTP)
for carcinogenicity testing in laboratory animals to further
assess these findings. 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 the EPA.
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How
can tungsten affect children? |
Children may be affected in the same
way as adults. We do not know whether children differ from
adults in their susceptibility to tungsten. Animal studies
have shown that tungsten can pass from the maternal blood
through the placenta and reach the fetus.
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How
can families reduce the risks of exposure to tungsten? |
- It is very unlikely that tungsten is present in the average
home or apartment at unsafe levels.
- Use bottled water if you have concerns about the presence
of tungsten in your tap water.
- If you live near a hazardous waste site containing tungsten,
prevent children from playing in dirt or eating dirt.
- If you get tungsten dust on your clothes, shower and change
your clothes before leaving your job and returning home.
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Is
there a medical test to determine whether I've been exposed
to tungsten? |
There are tests available to measure
tungsten in your blood, urine, hair, saliva, and feces. These
tests are not usually done in the doctor's office because
they require special equipment. Elevated levels of tungsten
in the feces can mean high recent tungsten exposure. Elevated
levels of tungsten in the urine and/or blood can mean high
tungsten consumption and/or high exposure. The average urine
concentration for the U.S. population was 0.083 µg/L
in 2003. Tests to measure tungsten in hair may provide information
on long-term tungsten exposure.
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Has
the federal government made recommendations to protect human
health? |
For tungsten and insoluble tungsten compounds
in air, the National Institute for Occupational Safety and
Health (NIOSH) recommends an exposure limit of 5 mg/m³
(average over a 10-hour period) and a short-term (15 minutes)
exposure limit of 10 mg/m³. The Occupational Safety and
Health Administration (OSHA) set limits for tungsten of 5
mg/m³ (insoluble compounds) and 1 mg/m³ (soluble
compounds) for construction and shipyard industries.
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References |
Agency for Toxic Substances and Disease
Registry (ATSDR). 2003. Toxicological
Profile for Tungsten (Draft for Public Comment). Atlanta,
GA: U.S. Department of Health and Human Services, Public Health
Service.
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Where can
I get more information? |
ATSDR can tell you where to find occupational
and environmental health clinics. Their specialists can recognize,
evaluate, and treat illnesses resulting from exposure to hazardous
substances. You can also contact your community or state health
or environmental quality department if you have any more questions
or concerns.
For more information, contact:
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Agency for Toxic Substances and Disease Registry
Division of Toxicology
1600 Clifton Road NE, Mailstop F-32
Atlanta, GA 30333
Phone: 1-888-42-ATSDR (1-888-422-8737)
FAX: (770)-488-4178
Email: ATSDRIC@cdc.gov
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