1,1,1Trichloroethane [factsheet]

1,1,1-TRICHLOROETHANE

Please Note: The main sources of information for this fact sheet are the Agency for Toxic Substances and Disease Registry's (ATSDR's) Toxicological Profile for 1,1,1-Trichloroethane and the Hazardous Substances Data Bank (HSDB), a database of summaries of peer-reviewed literature. Other secondary sources include the International Agency for Research on Cancer (IARC) monographs on chemicals carcinogenic to humans and the Handbook of Toxic and Hazardous Chemicals and Carcinogens.

Environmental/Occupational Exposure

Occupational exposure to 1,1,1-trichloroethane can occur during the use of metal degreasing agents, paints, glues, and cleaning products. (1)
Individuals are more likely to be exposed to 1,1,1-trichloroethane 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)
1,1,1-Trichloroethane 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 1,1,1-trichloroethane. However, these tests are not routinely available in hospitals and clinics. (1)

Health Hazard Information

Acute Effects:

Effects reported in humans due to acute (short-term) inhalation exposure to 1,1,1-trichloroethane include hypotension, mild hepatic effects, and 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. (1-4)
1,1,1-Trichloroethane is mildly irritating when applied to the skin. (1-4)
Tests involving acute exposure of animals, such as the LC₅₀ and LD₅₀ tests in rats, mice, rabbits, and guinea pigs, have demonstrated 1,1,1-trichloroethane to have low acute toxicity from inhalation or oral exposure and low to moderate acute toxicity from dermal exposure. (5)

Chronic Effects (Noncancer):

Most studies have not reported adverse effects from chronic (long-term) exposure to low levels of 1,1,1-trichloroethane. However, one study reported ventricular arrhythmias in humans repeatedly exposed to high concentrations of 1,1,1-trichloroethane, suggesting heart damage. (1)
Some liver damage has been observed in rodents chronically exposed to 1,1,1-trichloroethane by inhalation. (1,2)
The RfC for 1,1,1-trichloroethane is under review. (6)
EPA has not established an RfD for 1,1,1-trichloroethane. (6)
EPA's Office of Air Quality Planning and Standards, for a hazard ranking under Section 112(g) of the Clean Air Act Amendments, has evaluated 1,1,1-trichloroethane for chronic toxicity and has given it a composite score of 2 (scores range from 1 to 100, with 100 being the most toxic). These scores are nonlinear and are the product of two ratings: a rating based on the minimal-effect-dose and a rating based on the type of effect. (7)

Reproductive/Developmental Effects:

No information is available on the reproductive or developmental effects of 1,1,1-trichloroethane in humans.
Limited studies are available on the developmental effects of 1,1,1-trichloroethane by inhalation and oral exposure, and studies in several animal species found no evidence that the chemical has reproductive effects. (1,2,8,9)

Cancer Risk:

Information is not available on the carcinogenic effects of 1,1,1-trichloroethane in humans.
Two animal studies have not demonstrated carcinogenicity from exposure to 1,1,1-trichloroethane; 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 1,1,1-trichloroethane as a Group D, not classifiable as to human carcinogenicity, based on no reported human data and inadequate animal data. (6,8)

Physical Properties

The chemical formula for 1,1,1-trichloroethane is CH₃CCl₃, and its molecular weight is 133.42 g/mol. (1,10)
1,1,1-Trichloroethane occurs as a colorless, nonflammable liquid that is insoluble in water. (1,9,10)
1,1,1-Trichloroethane has a sweet yet sharp odor, similar to that of chloroform; the odor threshold is above 120 ppm (655 mg/m³). (1)
The vapor pressure for 1,1,1-trichloroethane is 124 mm Hg at 25 EC, and its log octanol/water partition coefficient (log K_ow) is 2.49. (1)

Uses

1,1,1-Trichloroethane 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)

1,1,1-Trichloroethane has recently found wide use as a substitute for carbon tetrachloride. (3)

Health Data from Inhalation Exposure

Concentration (mg/m³)	Health numbers^a	Regulatory, advisory numbers^b	Reference
100,000.0
_ _ _ _ 10,000.0	* LC₅₀ (rats) (98,210 mg/m³) * LC₅₀ (mice) (21,340 mg/m³)		5 5
_ _ _ _ 1,000.0		* ACGIH TLV, NIOSH REL, OSHA PEL, MSHA standard (1,900 mg/m³)	5

ACGIH TLVCAmerican Conference of Governmental and Industrial Hygienists' threshold limit value expressed as a time-weighted average; the concentration of a substance to which most workers can be exposed without adverse effectss.

LC₅₀ (Lethal Concentration₅₀)CA 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.

MSHACMine Safety and Health Administration.

NIOSH RELCNational Institute of Occupational Safety and Health's recommended exposure limit; NIOSH-recommended exposure limit for an 8- or 10-h time-weighted-average exposure and/or ceiling.

OSHA PELCOccupational 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.

^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.

References

1. Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for 1,1,1-Trichloroethane. U.S. Public Health Service, U.S. Department of Health and Human Services, Atlanta, GA. 1990.

2. 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.

3. M. Sittig. Handbook of Toxic and Hazardous Chemicals and Carcinogens. 2nd ed. Noyes Publications, Park Ridge, NJ. 1985.

4. 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.

5. 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.

6. U.S. Environmental Protection Agency. Integrated Risk Information System (IRIS) on 1,1,1-Trichloroethane. Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment, Office of Research and Development, Cincinnati, OH. 1993.

7. U.S. Environmental Protection Agency. Technical Background Document to Support Rulemaking Pursuant to the Clean Air ActCSection 112(g). Ranking of Pollutants with Respect to Hazard to Human Health. EPAB450/3-92-010. Emissions Standards Division, Office of Air Quality Planning and Standards, Research Triangle Park, NC. 1994.

8. 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.

9. 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.

10. The Merck Index. An Encyclopedia of Chemicals, Drugs, and Biologicals. 11th ed. Ed. S. Budavari. Merck and Co. Inc., Rahway, NJ. 1989.