Technology Transfer Network - Air Toxics Web Site
Methyl chloroform (1,1,1-Trichloroethane)
Hazard Summary-Created in April 1992; Revised in January 2000
Methyl chloroform is used as a solvent and in many consumer products.
Effects reported in humans due to acute (short-term) inhalation exposure
to methyl chloroform include hypotension, mild hepatic effects, and central
nervous system (CNS) depression. Cardiac arrhythmia and respiratory
arrest may result from the depression of the CNS. Symptoms of acute
inhalation exposure include dizziness, nausea, vomiting, diarrhea, loss
of consciousness, and decreased blood pressure in humans. After
chronic (long-term) inhalation exposure to methyl chloroform, some liver
damage was observed in mice and ventricular arrhythmias in humans.
EPA has classified methyl chloroform as a Group D, not classifiable as
to human carcinogenicity.
- Methyl chloroform is used as a solvent and degreasing agent in industry. It is an ingredient in consumer products such as household cleaners, glues, and aerosol sprays. (1,3,9)
- Methyl chloroform is also used as a chemical intermediate in the production of vinylidene chloride. It was formerly used as a food and grain fumigant. (1)
Sources and Potential Exposure
- Occupational exposure to methyl chloroform can occur during the use of metal degreasing agents, paints, glues, and cleaning products. (1)
- Individuals are more likely to be exposed to methyl chloroform indoors rather than outdoors because of its widespread use in home and office products. Exposure may also occur by the sniffing of glue or typewriter correction fluid. (1)
- Methyl chloroform has been detected in surface and groundwater; individuals may be exposed through the consumption of contaminated drinking water. (1)
Assessing Personal Exposure
- Samples of breath and urine can indicate the extent to which an individual has been exposed to methyl chloroform. However, these tests are not routinely available in hospitals and clinics. (1)
Health Hazard InformationAcute Effects:
- Effects reported in humans due to acute inhalation exposure to methyl chloroform include hypotension, mild hepatic effects, and CNS depression. Mild motor impairment (e.g., increased reaction time), lightheadedness, impaired balance, and ataxia have been reported in acutely exposed humans. Cardiac arrhythmia and respiratory arrest may result from the depression of the CNS. Symptoms of acute inhalation exposure include dizziness, nausea, vomiting, diarrhea, loss of consciousness, and decreased blood pressure. (1-4)
- Methyl chloroform is mildly irritating when applied to the skin of humans. (1-4)
- Neurological and liver effects have been observed in animals acutely exposed to methyl chloroform via inhalation. (1)
- Tests involving acute exposure of animals in rats, mice, rabbits, and guinea pigs have demonstrated methyl chloroform to have low acute toxicity from inhalation or oral exposure and low to moderate acute toxicity from dermal exposure. (5)
- Most studies have not reported adverse effects from chronic exposure to low levels of methyl chloroform in humans or animals. (1)
- Some liver damage and neurological effects have been observed in rodents chronically exposed to methyl chloroform by inhalation. (1,2)
- EPA has not established a Reference Concentration (RfC) or a Reference Dose (RfD) for methyl chloroform. (6)
- The California Environmental Protection Agency (CalEPA) has established a chronic reference exposure level of 1 milligram per cubic meter (mg/m3) based on CNS effects in gerbils. The CalEPA reference exposure level is a concentration at or below which adverse health effects are not likely to occur. It is not a direct estimator of risk but rather a reference point to gauge the potential effects. At lifetime exposures increasingly greater than the reference exposure level, the potential for health effects increases. (7)
- Epidemiologic studies have found no relationship between adverse pregnancy outcomes and exposure of mothers or fathers to methyl chloroform. (1)
- Animal studies have not reported developmental or reproductive effects from exposure to methyl chloroform. (1)
- Information is not available on the carcinogenic effects of methyl chloroform in humans.
- Two animal studies have not demonstrated carcinogenicity from oral or inhalation exposure to methyl chloroform; however, the data are considered to be inadequate due to the low survival of the rats in one study and the low dose levels used in the second study. (1,2,4,6,8,9)
- EPA has classified methyl chloroform as a Group D, not classifiable as to human carcinogenicity, based on no reported human data and inadequate animal data. (6)
- The chemical formula for methyl chloroform is CH3CCl3, and its molecular weight is 133.42 g/mol. (1,10)
- Methyl chloroform occurs as a colorless, nonflammable liquid that is insoluble in water. (1,9,10)
- Methyl chloroform has a sweet yet sharp odor, similar to that of chloroform; the odor threshold is above 120 parts per million (ppm). (1)
- The vapor pressure for methyl chloroform is 124 mm Hg at 20 °C, and its log octanol/water partition coefficient (log Kow) is 2.49. (1)
- Methyl chloroform is also called 1,1,1-trichloroethane. (1)
To convert concentrations in air (at 25 °C) from ppm to mg/m3: mg/m3 = (ppm) × (molecular weight of the compound)/(24.45). For methyl chloroform: 1 ppm = 5.4 mg/m3.
Health Data from Inhalation Exposure
ACGIH TLV--ACGIH's threshold limit value expressed as a time-weighted average; the concentration of a substance to which most workers can be exposed without adverse effects.
LC50 (Lethal Concentration50)--A calculated concentration of a chemical in air to which exposure for a specific length of time is expected to cause death in 50% of a defined experimental animal population.
NIOSH IDLH--National Institute of Occupational Safety and Health immediately dangerous to life and health; NIOSH concentration representing the maximum level of a pollutant from which an individual could escape within 30 minutes without escape-impairing symptoms or irreversible health effects.
NIOSH REL ceiling--NIOSH's recommended exposure limit ceiling; the concentration that should not be exceeded at any time.
OSHA PEL--Occupational Safety and Health Administration's permissible exposure limit expressed as a time-weighted average; the concentration of a substance to which most workers can be exposed without adverse effect averaged over a normal 8-h workday or a 40-h workweek.
The health and regulatory values cited in this factsheet were obtained
in December 1999.
a Health numbers are toxicological numbers from animal testing or risk assessment values developed by EPA.
b Regulatory numbers are values that have been incorporated in Government regulations, while advisory numbers are nonregulatory values provided by the Government or other groups as advice. OSHA numbers are regulatory, whereas NIOSH and ACGIH numbers are advisory.
c This NOAEL is from the critical study used as the basis for Cal EPA's chronic reference exposure level.
- Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for 1,1,1-Trichloroethane. (Update). U.S. Public Health Service, U.S. Department of Health and Human Services, Atlanta, GA. 1995. U.S.
- Department of Health and Human Services. Hazardous Substances Data Bank (HSDB, online database). National Toxicology Information Program, National Library of Medicine, Bethesda, MD. 1993.
- M. Sittig. Handbook of Toxic and Hazardous Chemicals and Carcinogens. 2nd ed. Noyes Publications, Park Ridge, NJ. 1985.
- U.S. Environmental Protection Agency. Health Assessment Document for 1,1,1-Trichloroethane (Methyl Chloroform). Revised Draft. EPA/600/8-82-003. Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment, Office of Research and Development, Cincinnati, OH. 1982.
- U.S. Department of Health and Human Services. Registry of Toxic Effects of Chemical Substances (RTECS, online database). National Toxicology Information Program, National Library of Medicine, Bethesda, MD. 1993.
- U.S. Environmental Protection Agency. Integrated Risk Information System (IRIS) on 1,1,1-Trichloroethane. National Center for Environmental Assessment, Office of Research and Development, Washington, DC. 1999.
- California Environmental Protection Agency (CalEPA). Air Toxics Hot Spots Program Risk Assessment Guidelines: Part III. Technical Support Document for the Determination of Noncancer Chronic Reference Exposure Levels. SRP Draft. Office of Environmental Health Hazard Assessment, Berkeley, CA. 1999.
- U.S. Environmental Protection Agency. Health Effects Assessment for 1,1,1-Trichloroethane. EPA/540/1-86-005. Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment, Office of Research and Development, Cincinnati, OH. 1984.
- International Agency for Research on Cancer (IARC). IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans: Some Halogenated Hydrocarbons. Volume 20. World Health Organization, Lyon. 1979.
- The Merck Index. An Encyclopedia of Chemicals, Drugs, and Biologicals. 11th ed. Ed. S. Budavari. Merck and Co. Inc., Rahway, NJ. 1989.
- American Conference of Governmental Industrial Hygienists (ACGIH). 1999 TLVs and BEIs. Threshold Limit Values for Chemical Substances and Physical Agents. Biological Exposure Indices. Cincinnati, OH. 1999.
- National Institute for Occupational Safety and Health (NIOSH). Pocket Guide to Chemical Hazards. U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention. Cincinnati, OH. 1997.
- Occupational Safety and Health Administration (OSHA). Occupational Safety and Health Standards, Toxic and Hazardous Substances. Code of Federal Regulations. 29 CFR 1910.1000. 1998.