Also known as: Dichloromethane, Methane dichloride, Methylene
Chemical reference number (CAS): 75-09-2
What is methylene chloride?
Methylene chloride is a clear, non-flammable liquid with a sweet, pleasant odor.
Its primarily used as paint remover, industrial solvent, and grain fumigant.
In the home, methylene chloride may be an ingredient in paint removers and in fire
extinguishers. You may find methylene chloride (or one of the other names listed above) in
the ingredient label of these products.
Methylene chloride will not remain in the food chain; sunlight will break down the
compound when released into the air. If methylene chloride is placed in a landfill or
discharged to soil, it can seep into groundwater and contaminate nearby wells.
How are people exposed to methyene chloride?
Breathing: Most cases of human exposure to methylene chloride occur
when people breathe vapors from paint strippers. Work only in well-ventilated areas if
working with with methylene chloride. When household water becomes contaminated, people
can inhale vapors while showering, laundering, and cooking.
When methylene chloride is used near an open flame, poisonous "phosgene" gas
can be created. Phosgene can cause permanent lung damage at low levels.
Drinking/Eating: People can be exposed when they drink contaminated
water or when they use it for preparing food.
Touching: Methylene chloride can be absorbed through the skin, but
this is a minor route of exposure.
Do standards exist for regulating methylene chloride?
Water: The drinking water standards for methylene chloride is set at 5
parts per billion (ppb). We suggest you stop drinking water containing more than 5 ppb of
methylene chloride. If levels of methylene chloride are high in your water (above 500
ppb), you may need to avoid washing, bathing, or using the water for other purposes.
Contact your local public health agency for more information specific to your situation.
Air: No standards exist for regulating the amount of methylene
chloride allowed in the air of homes. However, the Wisconsin Department of
Natural Resources (DNR) has set a residential indoor air action level for methylene
chloride at 15 parts per billion by volume (ppbv). The action level is
considered to be protective of public health. Breathing methylene chloride
for a lifetime at 15 ppbv is very unlikely to be harmful to people. If methylene
chloride concentrations in air are above the action level, we recommend
taking an action to halt exposure.
Most people can smell methylene chloride when the level reaches 1,000
ppbv. If you can smell the chemical, the level is too high to be safe.
The Wisconsin Department of Natural Resources regulates the amount of methylene
chloride that can be released into outdoor ambient air by industries.
Will exposure to methylene chloride result in harmful health
The following symptoms may occur immediately or shortly after exposure to levels of
methylene chloride at or above 300,000 ppbv in air:
- Increased levels of carbon monoxide in the blood which may cause fatigue, shortness of
breath or chest pain;
- Drowsiness, headache, a feeling of being "drunk," and
- Eye, skin and lung irritation.
These symptoms will disappear shortly after exposure stops.
The following health effects can happen after several years of exposure to methylene
Cancer: Laboratory animals have developed cancer after long-term
exposures to methylene chloride. The U.S. Environmental Protection Agency considers
methylene chloride to be a "probable" human carcinogen.
Reproductive Effects: Animal studies have shown no damage to
reproductive systems or developing unborn babies.
Organ Systems: Since methylene chloride changes to carbon monoxide in
the body, it can damage the heart and nervous system.
In general, chemicals affect the same organ systems in all people who are exposed.
However, the seriousness of the effects may vary from person to person. A person's
reaction depends on several things, including individual health, heredity, previous
exposure to chemicals including medicines, and personal habits such as smoking or
It is also important to consider the length of exposure to the chemical; the amount of
chemical exposure; and whether the chemical was inhaled, touched, or eaten.
Can a medical test determine exposure to methylene chloride?
Exposure to high levels of methylene chloride will temporarily increase carbon monoxide
(carboxyhemoglobin) in the blood and may affect liver function. Levels of
carboxyhemoglobin are usually higher in people who smoke. Methylene chloride can be
measured in urine or exhaled breath shortly after exposure. Although the tests can be used
to confirm exposure, they may not predict future health problems.
Seek medical advice if you have any symptoms that you think may be related to chemical
(P-44348 Revised 05/2012)
This fact sheet summarizes information about this chemical and is not a complete
listing of all possible effects. It does not refer to work exposure or emergency
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