ToxFAQsTM for Methyl Mercaptan
Spanish: Metil Mercaptano
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This fact sheet answers the most frequently
asked health questions about methyl mercaptan. 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.
is a natural substance released from decaying matter.
Little is known about the health effects of this compound.
This chemical has been found in at least 2 of the 1,300
National Priorities List sites identified by the Environmental
Protection Agency (EPA).
What is methyl mercaptan?
Methyl mercaptan is a colorless gas with
a smell like rotten cabbage. It is a natural substance found
in the blood, brain, and other tissues of people and animals.
It is released from animal feces. It occurs naturally in certain
foods, such as some nuts and cheese.
Methyl mercaptan is released from decaying
organic matter in marshes and is present in the natural gas
of certain regions in the United States, in coal tar, and
in some crude oils. It is manufactured for use in the plastics
industry, in pesticides, and as a jet fuel additive. It is
also released as a decay product of wood in pulp mills.
What happens to methyl mercaptan when it enters the environment?
- Methyl mercaptan is released to the air from both natural
and industrial sources.
- Most of the methyl mercaptan released to the environment
goes into the air.
- Sunlight can break it down in the air to other substances.
- Methyl mercaptan may be formed in water from chemical
- It occurs naturally in soil.
How might I be exposed to methyl mercaptan?
- Methyl mercaptan is always present in your body.
- You may breathe it in the air if you live near a natural
source of the gas, such as a marsh.
- You may eat it in certain foods, such as nuts and cheese.
- You may be exposed if you work at a wood-pulp mill or
sewage treatment plant.
- You could also be exposed if you work in a factory that
uses it to make other products such as jet fuel, pesticides,
or poultry feed.
How can methyl mercaptan affect my health?
Very little is known about the health
effects of methyl mercaptan. The only information available
is about a worker exposed to very high levels of this compound
when he opened and emptied tanks of this compound. He developed
anemia, went into a coma, and died about a month later.
We do not know whether long-term exposure
to low levels of methyl mercaptan can result in harmful health
How likely is methyl mercaptan to cause cancer?
There is no information available about
whether methyl mercaptan causes cancer in people or animals.
The Department of Health and Human Services (DHHS), the International
Agency for Research on Cancer (IARC), and the EPA have not
classified methyl mercaptan for carcinogenicity.
Is there a medical test to show whether I've been exposed to methyl mercaptan?
Methyl mercaptan is always present in
your body. There is a test that can be used to find out if
it is present in your blood at levels that are higher than
normal. This test requires special equipment and is not usually
available in a doctor's office. It can be done in a special
laboratory. However, this test cannot be used to find out
how much methyl mercaptan you were exposed to or to predict
whether harmful health effects will occur.
Has the federal government made recommendations to protect human health?
The EPA requires that discharges, spills,
or accidental releases of 100 pounds or more of methyl mercaptan
must be reported to the EPA.
The Occupational Safety and Health Administration (OSHA) has set a permissible exposure limit of 20 milligrams of methyl mercaptan per cubic meter of air (20 mg/m3) for an 8-hour workday in a 40-hour workweek.
The American Conference of Governmental and Industrial Hygienists (ACGIH) and the National Institute for Occupational Safety and Health (NIOSH) recommend an occupational exposure limit of 1 mg/m3 for methyl mercaptan.
The federal recommendations have been
updated as of July 1999.
Anemia: A decreased ability of the blood
to transport oxygen.
Carcinogenicity: Ability to cause cancer.
CAS: Chemical Abstracts Service.
Long-term: Lasting one year or longer.
Milligram (mg): One thousandth of a gram.
National Priorities List: A list of the
nation's worst hazardous waste sites.
Pesticide: A substance that kills pests.
Agency for Toxic Substances and Disease
Registry (ATSDR). 1999. Managing Hazardous Materials Incidents.
Volume III – Medical Management Guidelines for Acute
Chemical Exposures: Methyl Mercaptan. Atlanta,
GA: U.S. Department of Health and Human Services, Public Health
Agency for Toxic Substances and Disease
Registry (ATSDR). 1992. Toxicological
Profile for methyl mercaptan. 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
Division of Toxicology and Human Health Sciences
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.