ToxFAQsTM for Methyl Isocyanate
Spanish: Metil Isocianato
CAS#: 624-83-9
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This fact sheet answers the most frequently asked health questions about methyl isocyanate. For more information, you may call the ATSDR Information Center at 1-800-232-4636. This fact sheet is one in a series of summaries about hazardous substances and their health effects. It is important you understand this information 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.
Highlights
People working in facilities that produce or use methyl isocyanate have the highest risk of being exposed to this chemical. Exposure to low levels of methyl isocyanate can cause eye and throat irritation. People exposed to high levels of methyl isocyanate in the air have experienced severe lung and eye damage. Methyl isocyanate has been found in at least 1 of the 1,585 National Priorities List sites identified by the Environmental Protection Agency (EPA).
What is methyl isocyanate?
Methyl isocyanate is a colorless highly
flammable liquid that evaporates quickly when exposed to the
air. It has a sharp, strong odor.
Methyl isocyanate is used in the production
of pesticides, polyurethane foam, and plastics.
What happens to methyl isocyanate when it enters the environment?
- When released to air, it will exist solely as a gas. Methyl
isocyanate gas is degraded rapidly in the air by reacting
with substances commonly found in the air. Methyl isocyanate
will also be broken down by moisture from clouds and rainfall.
It will only persist in the atmosphere a few hours to a
few days before being degraded.
- Methyl isocyanate is rapidly (minutes to a few hours)
degraded in water into other compounds.
- Most of the methyl isocyanate released to soil will be
broken down into other compounds upon contact with moisture.
Small amounts of methyl isocyanate may evaporate into air.
- Methyl isocyanate does not accumulate in the food chain.
How might I be exposed to methyl isocyanate?
- Methyl isocyanate has been found in the smoke from tobacco,
so people who smoke or breathe second-hand smoke may be
exposed to this compound.
- You can be exposed to methyl isocyanate by breathing or
touching it at workplaces where this compound is produced
or used.
- People living near facilities which manufacture, store
or use the chemical may breathe in low levels of it.
How can methyl isocyanate affect my health?
Methyl isocyanate can be harmful if you
breathe it. The effects depend on how much you are exposed
to and for how long. Exposure to low levels might cause eye
and throat irritation that could cause you to cough or wheeze.
Higher concentrations of methyl isocyanate gas could cause
your lungs to swell, making it difficult to breathe. This
could happen quickly or might not be noticed for a day or
two. Exposure to high concentrations could result in severe
damage to your lungs that might be fatal. If you were to survive
severe damage to your lungs, they would probably heal. But,
some damage might not be completely repaired.
Long-term exposure to methyl isocyanate
could result in long-term lung damage.
If you were to get methyl isocyanate
gas or liquid on your skin or in your eyes, you could develop
chemical burns. Eye damage could be severe; in some cases,
it could be permanent.
You are not likely to come into skin
contact with liquid methyl isocyanate. You are also not likely
to swallow methyl isocyanate liquid, but if you did, your
mouth, throat, esophagus, and stomach could become damaged.
An increased rate of spontaneous abortion
was seen in women who were pregnant when they were exposed
to methyl isocyanate gas following the explosion of a tank
containing liquid methyl isocyanate. But it is not known whether
these effects were specifically linked to methyl isocyanate
exposure.
How likely is methyl isocyanate to cause cancer?
The Department of Health and Human Services
(DHHS), the International Agency for Research on Cancer (IARC),
and the U.S. EPA have not classified methyl isocyanate as
to its carcinogenicity. There is no additional information
to determine whether exposure to methyl isocyanate might cause
cancer.
How does methyl isocyanate affect children?
There are no studies on the health effects
of children exposed to methyl isocyanate. It is likely that
the health effects seen in children exposed to methyl isocyanate
will be similar to the effects seen in adults. We do not know
whether children differ from adults in their susceptibility
to methyl isocyanate.
An increased rate of neonatal death was
seen in babies whose mothers had been exposed during pregnancy
to methyl isocyanate gas when a tank containing the chemical
exploded. But it is not known whether these effects were specifically
linked to methyl isocyanate exposure. Animal studies indicate
that fetal exposure to methyl isocyanate may result in damage
to the fetus.
How can families reduce the risk of exposure to methyl isocyanate?
Most families will not be exposed to
significant levels of methyl isocyanate.
Is there a medical test to show whether I've been exposed to methyl isocyanate?
Animal studies indicate that methyl isocyanate
could be detected in your blood or urine. However, specific
tests for the presence of methyl isocyanate in blood or urine
are not generally useful. If you suspect that you may have
been exposed to methyl isocyanate, chest x-rays, blood analyses,
and breathing tests might show whether the lungs have been
injured.
Has the federal government made recommendations to
protect human health?
The Occupational Safety and Health Administration
(OSHA) has set an exposure limit of 0.02 parts of methyl isocyanate
per million parts of workplace air (0.02 ppm) for an 8-hour
workday, 40-hour work week.
References
Agency for Toxic Substances and Disease
Registry (ATSDR). 2002. Managing Hazardous Materials Incidents.
Volume III — Medical Management Guidelines for Acute
Chemical Exposures: Methyl Isocyanate. Atlanta, GA: U.S. Department
of Health and Human Services, Public Health Service.
Where can I get more information?
If you have questions or concerns, please contact your community or state health or environmental quality department or:
For more information, contact:
Agency for Toxic Substances and Disease Registry
Office of Innovation and Analytics, Toxicology Section
4770 Buford Highway
Chamblee, GA 30341-3717
Phone: 1-800-CDC-INFO 888-232-6348 (TTY)
Email: Contact CDC-INFO
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.