1.1 What is trichloroethylene? |
1.2 What happens to trichloroethylene
when it enters the environment? |
1.3 How might I be exposed to trichloroethylene? |
1.4 How can trichloroethylene enter and
leave my body? |
1.5 How can trichloroethylene affect my
health? |
1.6 Is there a medical test to determine
whether I have been exposed to trichloroethylene? |
1.7 What recommendations has the federal
government made to protect human health? |
1.8 Where can I get more information? |
References |
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DATE |
Public Health Statement |
for |
Trichloroethylene |
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This Public Health Statement is the
summary chapter from the Toxicological
Profile for trichloroethylene. It is one in a series of
Public Health Statements about hazardous substances and their
health effects. A shorter version, the ToxFAQs™,
is also available. 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. For more information, call the ATSDR Information
Center at 1-888-422-8737.
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This public health statement tells you about trichloroethylene
and the effects of exposure.
The Environmental Protection Agency (EPA) has identified
1,428 hazardous waste sites as the most serious in the nation.
These sites make up the National Priorities List (NPL) and
are targeted for long-term federal clean-up. Trichloroethylene
has been found in at least 861 NPL sites. However, it's unknown
how many NPL sites have been evaluated for this substance.
As EPA looks at more sites, the sites with trichloroethylene
may increase. This is important because exposure to this substance
may harm you and because these sites may be sources of exposure.
When a substance is released from a large area, such as an
industrial plant, or from a container, such as a drum or bottle,
it enters the environment. This release does not always lead
to exposure. You are exposed to a substance only when you
come in contact with it by breathing, eating, touching, or
drinking.
If you are exposed to trichloroethylene, many factors will
determine whether you'll be harmed. These factors include
the dose (how much), the duration (how long), and how you
come in contact with it. You must also consider the other
chemicals you're exposed to and your age, sex, diet, family
traits, lifestyle, and state of health.
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1.1
What is trichloroethylene? |
Trichloroethylene is also known as Triclene
and Vitran and by other trade names in industry. It is a nonflammable,
colorless liquid at room temperature with a somewhat sweet
odor and a sweet, burning taste. Trichloroethylene is now
mainly used as a solvent to remove grease from metal parts.
It is also used as a solvent in other ways and is used to
make other chemicals. Trichloroethylene can also be found
in some household products, including typewriter correction
fluid, paint removers, adhesives, and spot removers. Most
people can begin to smell trichloroethylene in air when there
are around 100 parts of trichloroethylene per million parts
of air (ppm).
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1.2
What happens to trichloroethylene when it enters the environment? |
By far, the biggest source of trichloroethylene
in the environment is evaporation from factories that use
it to remove grease from metals. It can also enter the air
and water when it is disposed of at chemical waste sites.
It evaporates easily but can stay in the soil and in groundwater.
Once it is in the air, about half will be broken down within
a week. When trichloroethylene is broken down in the air,
phosgene, a lung irritant, can be formed. Trichloroethylene
can break down under high heat and alkaline conditions to
form dichloroacetylene and phosgene. In the body, trichloroethylene
may break down into dichloroacetic acid (DCA), trichloroacetic
acid (TCA), chloral hydrate, and 2-chloroacetaldehyde. These
products have been shown to be toxic to animals and are probably
toxic to humans. Once trichloroethylene is in water, much
will evaporate into the air; again, about half will break
down within a week. It will take days to weeks to break down
in surface water. In groundwater the breakdown is much slower
because of the much slower evaporation rate. Very little trichloroethylene
breaks down in the soil, and it can pass through the soil
into underground water. It is found in some foods. The trichloroethylene
found in foods is believed to come from contamination of the
water used in food processing, or from food processing equipment
cleaned with trichloroethylene. It does not build up in fish,
but low levels have been found in them.
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1.3
How might I be exposed to trichloroethylene? |
Trichloroethylene is found in the outdoor
air at levels far less than 1 ppm. When measured several years
ago, some of the water supplies in the United States were
found to have trichloroethylene. The most recent monitoring
study found average levels in surface water ranging from 0.0001
to 0.001 ppm of water and an average level of 0.007 ppm in
groundwater. About 400,000 workers are routinely exposed to
trichloroethylene in the United States. The chemical can also
get into the air or water in many ways, for example, at waste
treatment facilities; by evaporation from paints, glues, and
other products; or by release from factories where it is made.
Another way you may be exposed is by breathing the air around
factories that use the chemical. People living near hazardous
waste sites may be exposed to it in the air or in their drinking
water, or in the water used for bathing or cooking. Products
that may contain trichloroethylene are some types of typewriter
correction fluids, paints and paint removers, glues, spot
removers, rug cleaning fluids, and metal cleaners.
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1.4
How can trichloroethylene enter and leave my body? |
Trichloroethylene enters your body when you breathe air or
drink water containing it. It can also enter your body if
you get it on your skin. You could be exposed to contaminated
water or air if you live near or work in a factory that uses
trichloroethylene or if you live near a waste disposal site
that contains trichloroethylene. If you breathe the chemical,
about half the amount you breathe in will get into your bloodstream
and organs. You will exhale the rest. If you drink trichloroethylene,
most of it will be absorbed into your blood. If trichloroethylene
comes in contact with your skin, some of it can enter your
body, although not as easily as when you breathe or swallow
it.
Once in your blood, your liver changes much of the trichloroethylene
into other chemicals. The majority of these breakdown products
leave your body in the urine within a day. You will also quickly
breathe out much of the trichloroethylene that is in your
bloodstream. Some of the trichloroethylene or its breakdown
products can be stored in body fat for a brief period, and
thus may build up in your body if exposure continues.
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1.5
How can trichloroethylene affect my health? |
To protect the public from the harmful effects of toxic chemicals
and to find ways to treat people who have been harmed, scientists
use many tests.
One way to see if a chemical will hurt people is to learn
how the chemical is absorbed, used, and released by the body;
for some chemicals, animal testing may be necessary. Animal
testing may also be used to identify health effects such as
cancer or birth defects. Without laboratory animals, scientists
would lose a basic method to get information needed to make
wise decisions to protect public health. Scientists have the
responsibility to treat research animals with care and compassion.
Laws today protect the welfare of research animals, and scientists
must comply with strict animal care guidelines.
Trichloroethylene was once used as an anesthetic for surgery.
People who are exposed to large amounts of trichloroethylene
can become dizzy or sleepy and may become unconscious at very
high levels. Death may occur from inhalation of large amounts.
Many people have jobs where they work with trichloroethylene
and can breathe it or get it on their skin. Some people who
get concentrated solutions of trichloroethylene on their skin
develop rashes. People who breathe moderate levels of trichloroethylene
may have headaches or dizziness. It is possible that some
people who breathe high levels of trichloroethylene may develop
damage to some of the nerves in the face. People have reported
health effects when exposed to the level of trichloroethylene
at which its odor is noticeable. Effects have also occurred
at much higher levels. The effects reported at high levels
include liver and kidney damage and changes in heart beat.
The levels at which these effects occur in humans are not
well characterized. Animals that were exposed to moderate
levels of trichloroethylene had enlarged livers, and high-level
exposure caused liver and kidney damage.
It is uncertain whether people who breathe air or drink water
containing trichloroethylene are at higher risk of cancer,
or of having reproductive effects. More and more studies suggest
that more birth defects may occur when mothers drink water
containing trichloroethylene. People who used water for several
years from two wells that had high levels of trichloroethylene
may have had a higher incidence of childhood leukemia than
other people, but these findings are not conclusive. In another
study of trichloroethylene exposure from well water, increased
numbers of children were reported to be born with heart defects,
which is supported by data from some animal studies showing
developmental effects of trichloroethylene on the heart. However,
other chemicals were also in the water from this well and
may have contributed to these effects.One study reported a
higher number of children with a rare defect in the respiratory
system and eye defects. Another study reported that the risk
for neural tube defects and oral cleft palates were higher
among mothers with trichloroethylene in their water during
pregnancy. Children listed in the National Exposure Subregistry
of persons exposed to trichloroethylene were reported to have
higher rates of hearing and speech impairment. There are many
questions regarding these reports. There were small numbers
of children with defects and trichloroethylene levels at which
the effects occurred were not defined well. Thus, it is not
possible to make firm conclusions about the exact effects
of trichloroethylene from these studies, and more studies
need to be done.
We do not have any clear evidence that trichloroethylene
alone in drinking water can cause leukemia or any other type
of cancer in humans. As part of the National Exposure Subregistry,
the Agency for Toxic Substances and Disease Registry (ATSDR)
compiled data on 4,280 residents of three states (Michigan,
Illinois, and Indiana) who had environmental exposure to trichloroethylene.
It found no definitive evidence for an excess of cancers from
trichloroethylene exposure. An increase of respiratory cancer
was noted in older men, but this effect was thought to result
from smoking rather than trichloroethylene exposure. A study
in New Jersey found an association between leukemia in women
and exposure to trichloroethylene in the drinking water. A
study in Massachusetts found that exposure was associated
with leukemia in children.In studies with people, there are
many factors that are not fully understood. More studies need
to be done to establish the relationship between exposure
to trichloroethylene and cancer.
In studies using high doses of trichloroethylene in rats
and mice, tumors in the lungs, liver, and testes were found,
providing some evidence that high doses of trichloroethylene
can cause cancer in experimental animals. Based on the limited
data in humans regarding trichloroethylene exposure and cancer,
and evidence that high doses of trichloroethylene can cause
cancer in animals, the International Agency for Research on
Cancer (IARC) has determined that trichloroethylene is probably
carcinogenic to humans. Trichloroethylene has been nominated
for listing in the National Toxicology Program (NTP) 9th Report
on Carcinogens. Evaluation of this substance by the NTP review
committee is ongoing.
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1.6
Is there a medical test to determine whether I have been exposed
to trichloroethylene? |
There are some tests that can show if
you have been recently exposed to trichloroethylene since
this chemical can be measured in your breath. Also, a doctor
can have trichloroethylene or a number of breakdown products
of trichloroethylene measured in your urine or blood. None
of these tests, however, is routinely available at your doctor's
office. If the measurements are done soon after the exposure,
the breath levels can indicate whether you have been exposed
to a large amount of trichloroethylene or only a small amount.
Urine and blood tests can also show if you have been exposed
to large amounts of this chemical. Because one of the breakdown
products leaves your body very slowly, it can be measured
in the urine for up to about 1 week after trichloroethylene
exposure. However, exposure to other similar chemicals can
produce the same breakdown products in your urine and blood.
Therefore, these methods cannot determine for sure whether
you have been exposed to trichloroethylene.
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1.7
What recommendations has the federal government made to protect
human health? |
The federal government develops regulations
and recommendations to protect public health. Regulations
can be enforced by law. Federal agencies that develop
regulations for toxic substances include the Environmental
Protection Agency (EPA), the Occupational Safety and Health
Administration (OSHA), and the Food and Drug Administration
(FDA). Recommendations provide valuable guidelines to protect
public health but cannot be enforced by law. Federal
organizations that develop recommendations for toxic substances
include the Agency for Toxic Substances and Disease Registry
(ATSDR) and the National Institute for Occupational Safety
and Health (NIOSH).
Regulations and recommendations can be expressed in not-to-exceed
levels in air, water, soil, or food that are usually based
on levels that affect animals, then they are adjusted to help
protect people. Sometimes these not-to-exceed levels differ
among federal organizations because of different exposure
times (an 8-hour workday or a 24-hour day), the use of different
animal studies, or other factors.
Recommendations and regulations are also periodically updated
as more information becomes available. For the most current
information, check with the federal agency or organization
that provides it. Some regulations and recommendations for
trichloroethylene include the following.
EPA has set a drinking water standard of 5 parts of trichloroethylene
per one billion parts of water (ppb). One ppb is 1,000 times
less than 1 ppm. This standard became effective on January
9, 1989, and applies to community water systems and those
that serve the same 25 or more persons for at least 6 months.
EPA requires industries to report spills of 1,000 pounds or
more of trichloroethylene. It has been proposed that this
level be reduced to 100 pounds.
Trichloroethylene levels in the workplace are regulated by
the Occupational Safety and Health Administration (OSHA).
The occupational exposure limit for an 8-hour workday, 40-hour
workweek, is an average concentration of 100 ppm in air. The
15-minute average exposure in air that should not be exceeded
at any time during a workday is 300 ppm. The OSHA standards
are based on preventing central nervous system effects after
trichloroethylene exposure.
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1.8 Where can I get more information? |
If you have any more questions or concerns, please contact
your community or state health or environmental quality department or:
Agency for Toxic Substances and Disease Registry
Division of Toxicology
1600 Clifton Road NE, Mailstop F-32
Atlanta, GA 30333
Information line and technical assistance:
Phone: 888-422-8737
FAX: (770)-488-4178
ATSDR can also tell you the location of occupational and environmental health
clinics. These clinics specialize in recognizing, evaluating, and treating illnesses
resulting from exposure to hazardous substances.
To order toxicological profiles, contact:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Phone: 800-553-6847 or 703-605-6000
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References |
Agency for Toxic Substances and Disease
Registry (ATSDR). 1997. Toxicological
profile for trichloroethylene. Atlanta, GA: U.S. Department
of Health and Human Services, Public Health Service.
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