1.1 What is HDI? |
1.2 What happens to HDI when it enters
the environment? |
1.3 How might I be exposed to HDI? |
1.4 How can HDI enter and leave my body? |
1.5 How can HDI affect my health? |
1.6 Is there a medical test to determine
whether I have been exposed to HDI? |
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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August 1998 |
Public Health Statement |
for |
Hexamethylene Diisocyanate (HDI) |
(Diisocianato de Hexametileno (HDI)) |
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This Public Health Statement is the
summary chapter from the Toxicological
Profile for hexamethylene hiisocyanate (HDI). 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 hexamethylene diisocyanate (HDI) and the effects of
exposure.
The Environmental Protection Agency (EPA)
identifies the most serious hazardous waste sites in the nation.
These sites make up the National Priorities List (NPL) and
are the sites targeted for long-term federal clean-up activities.
Hexamethylene diisocyanate has not been found in any of the
1,445 current or former NPL sites. However, the total
number of NPL sites evaluated is not known. As more
sites are evaluated, the number of sites at which HDI is found
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 can be
exposed to a substance only when you come in contact with
it by breathing, eating, touching, or drinking.
If you are exposed to hexamethylene diisocyanate,
many factors 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 HDI? |
HDI is the common name for hexamethylene
diisocyanate. It is also known as 1,6-hexamethylene
diisocyanate, 1,6-diisocyanatohexane, Mondur HX, and Desmodur
H. It is a pale yellow liquid with a strong odor.
HDI is found in hardening agents for automobile
paints.
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1.2
What happens to HDI when it enters the environment? |
HDI is most often found in air near locations
where spray paints that contain it as a hardening agent are
used. HDI in the air can enter the soil and water.
HDI can also enter the soil if products containing it are
dumped directly onto the soil. HDI can enter the water
supply by washing out of soil that contains it or if products
with HDI are dumped directly into water. Once it is
in soil or water, HDI does not easily evaporate, so general
air pollution is not expected. HDI breaks down very
quickly in water or sunlight, so it probably will not build
up in the environment.
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1.3
How might I be exposed to HDI? |
The most common products that contain
HDI are called hardening agents and are used to spray-paint
cars. The most common way a person can be exposed to
HDI is by breathing air that contains it as a vapor or mist,
like that made when spray-painting a car. Most of the
people who are exposed to HDI work in the automotive painting
industry or in areas where this is done. If you do this
kind of work, you can be exposed to more HDI if you do not
wear the right protective safety equipment such as a respirator
or mask. If your safety equipment does not fit right
or does not work properly when you are using products that
contain HDI, you may be exposed to larger amounts. You
can probably absorb some HDI through your skin. You
could also accidentally swallow HDI if it is on your hands
and you do not wash them before eating, drinking, or smoking.
Unless you have been employed in the
automobile refinishing or other business where painters manually
mix two-component polyurethane paint systems, it is unlikely
that you will be exposed to large amounts of HDI.
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1.4
How can HDI enter and leave my body? |
The most common way HDI enters your body
is by breathing air that has it in it. You can probably
absorb some HDI through your skin, and you can also accidentally
swallow HDI if it is on your hands and you do not wash them
before eating, drinking, or smoking. Once inside your
body, HDI breaks down very quickly and is quickly excreted
in the urine. Some HDI can attach itself to protein
in your blood, but we do not know how long it takes for this
form of HDI to break down and be excreted.
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1.5
How can HDI 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.
How HDI affects your health depends on
how much is in the air you breathe. Tests using laboratory
animals showed that breathing in high concentrations of HDI
can irritate the nose, eyes, and throat. High concentrations
have also caused pneumonia, difficulty in breathing, and death
in some animals. Swallowing high concentrations of HDI
also killed laboratory animals. When placed on the skin
of these animals, HDI caused redness, irritation, and irreversible
skin damage. People would probably be affected in many
of the same ways if they were exposed to large amounts of
HDI in air.
Many people who breathe in vapors from
products with small amounts of HDI for many months or many
years may develop an allergic, asthma-like reaction.
Symptoms usually develop very slowly over a long time (months
or years), but they can also develop within a couple of weeks
after first breathing in HDI. At low concentrations,
sensitized workers develop a burning sensation and a feeling
of tightness in the chest, a cough (with and without phlegm),
fever, and chills. They have a hard time breathing during
their work day when using a product containing HDI.
These signs usually are not seen on weekends, during vacations,
or any time the person is not using a product that contains
HDI. These reactions usually begin again soon after
the person returns to work and begins to use the product with
HDI.
Some studies in laboratory animals showed
that, when breathed in over a long time, HDI did not produce
cancer. No studies that show that HDI can cause cancer
in people have been found.
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1.6
Is there a medical test to determine whether I have been exposed
to HDI? |
Before you ask for special medical tests
for HDI, you should talk with your doctor and tell him you
work in a place that uses products that contain HDI.
There are no good medical tests for finding out if you have
been exposed to HDI. Some tests are available that measure
the antibodies against HDI your body makes after you have
been exposed to it. However, these blood tests are not
very good because they can react with other substances
that look like HDI in your blood. The test can show
that you have been exposed to HDI when really you have not
been exposed to it (false positives). Also, some people
do not develop antibodies to HDI after they have been exposed.
Another test looks for the breakdown products of HDI in the
urine. This test is only good if you were exposed to HDI within
the last 12–15 hours. It is not a good test to find
out if you have been exposed to low amounts of HDI over many
months or years.
Unless you have been employed in the
automobile refinishing or other business where painters manually
mix two-component polyurethane paint systems, it is unlikely
that you have been exposed to significant amounts of HDI.
Your doctor can give you more information on medical tests
that are available for determining if you have been exposed
to HDI.
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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 HDI include the following.
The EPA proposes to list HDI as a
hazardous substance that will be required to be reported under
the Emergency Planning and Community Right-to-Know Act for
1986 and the Pollution Prevention Act of 1990. Currently,
some owners and operators using HDI are required to report
every year how much HDI they release into the environment.
The NIOSH-recommended limit for occupational
exposure is 0.035 milligrams of HDI per cubic meter of air
(.035 mg/m³), which is the same as 5 parts per billion
(ppb). There is no established OSHA permissible exposure
limit (PEL) for HDI at this time; however, a similar substance,
toluene diisocyanate (TDI), has a PEL of 5 parts per billion
(ppb).
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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). 1998. Toxicological
profile for hexamethylene diisocyanate (HDI). Atlanta,
GA: U.S. Department of Health and Human Services, Public Health
Service.
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