1,1,2Trichloroethane [factsheet]

1,1,2-TRICHLOROETHANE

Please Note: The main sources of information for this fact sheet are EPA's Integrated Risk Information System (IRIS), which contains information on inhalation chronic toxicity of 1,1,2-trichloroethane and the RfC, oral chronic toxicity and the RfD, and the carcinogenic effects of 1,1,2-trichloroethane including the unit cancer risk for inhalation exposure, and the Agency for Toxic Substances and Disease Registry's (ATSDR's) Toxicological Profile for 1,1,2-Trichloroethane. Other secondary sources include the Hazardous Substances Data Bank (HSDB), a database of summaries of peer-reviewed literature, and the Registry of Toxic Effects of Chemical Substances (RTECS), a database of toxic effects that are not peer reviewed.

Environmental/Occupational Exposure

* Very low levels of 1,1,2-trichloroethane have been detected in ambient air; the samples tested usually contained around 0.01 to 0.05 ppb of 1,1,2-trichloroethane. (1)

* 1,1,2-Trichloroethane has not been reported in food or soil, and exposure from contaminated drinking water appears to be rare. (1)

* Exposure to 1,1,2-trichloroethane may occur in the workplace where it is used as a solvent. (1)

Assessing Personal Exposure

* There is no commonly used medical test to measure exposure to 1,1,2-trichloroethane. (1)

Health Hazard Information

Acute Effects:

* No information is available on the acute (short-term) effects of 1,1,2-trichloroethane in humans from inhalation or oral exposures. Studies on dermal exposure to 1,1,2-trichloroethane in humans have reported stinging and burning sensations and transient whitening of the skin. (1)

* Animal studies have reported effects on the liver, kidney, and central nervous system from inhalation and oral exposure to 1,1,2-trichloroethane. (1)

* Tests involving acute exposure of animals, such as the LC₅₀ and LD₅₀ tests in mice and rats, have shown 1,1,2-trichloroethane to have moderate to high acute toxicity from inhalation and oral exposures, respectively. (1,2)

Chronic Effects (Noncancer):

* No information is available on the chronic (long-term) effects of 1,1,2-trichloroethane in humans from inhalation or oral exposure. (1)

* Animal studies have not observed adverse effects from chronic inhalation exposure to 1,1,2-trichloroethane. Effects on the liver and immune system have been noted in chronic oral studies. (1)

* The RfC for 1,1,2-trichloroethane is under review by EPA. (3)

* The RfD for 1,1,2-trichloroethane is 0.004 mg/kg/d based on clinical serum chemistry in mice. (3)

* EPA has medium confidence in the critical study on which the RfD is based because of its balanced strengths (clinical chemistries) and weaknesses (lack of histopathology and a no-observed-adverse-effect level [NOAEL]); medium confidence in the supporting database; and, consequently, medium confidence in the RfD. (3)

Reproductive/Developmental Effects:

* No information is available regarding developmental or reproductive effects of 1,1,2-trichloroethane in humans from inhalation or oral exposure. (1)

* Animal studies have not reported developmental or reproductive effects from inhalation or oral exposure to 1,1,2-trichloroethane. (1)

Cancer Risk:

* No studies are available regarding cancer in humans from inhalation or oral exposure. (1)

* No animal studies are available on cancer via inhalation exposure. One animal study reported liver tumors and adrenal tumors in mice, but no tumors in rats from exposure to 1,1,2-trichloroethane by gavage (experimentally placing the chemical in the stomach). (1,3)

* EPA has classified 1,1,2-trichloroethane as a Group C, possible human carcinogen. (3)

* EPA uses mathematical models, based on animal studies, to estimate the probability of a person developing cancer from breathing air containing a specified concentration of a chemical. EPA has calculated an inhalation unit risk estimate of 1.6 H 10^-5(m g/m³)^-1. EPA estimates that, if an individual were to breathe air containing 1,1,2-trichloroethane at 0.06 Fg/m³* over his or her entire lifetime, that person would theoretically have no more than a one-in-a-million increased chance of developing cancer as a direct result of breathing air containing this chemical. Similarly, EPA estimates that breathing air containing 0.6 Fg/m³ would result in not greater than a one-in-a-hundred thousand increased chance of developing cancer, and air containing 6.0 Fg/m³ would result in not greater than a one-in-ten thousand increased chance of developing cancer. (3)

* EPA's Office of Air Quality Planning and Standards, for a hazard ranking under Section 112(g) of the Clean Air Act Amendments, has ranked 1,1,2-trichloroethane in the nonthreshold category. The 1/ED₁₀ value is 0.21 per (mg/kg)/d and this would place it in the low category under Superfund's ranking for carcinogenic hazard. (4)

Physical Properties

* The chemical formula for 1,1,2-trichloroethane is C₂H₃Cl₃, and the molecular weight is 133.41. (1)

* 1,1,2-Trichloroethane is a colorless, sweet-smelling liquid; the odor threshold is not available. (1,5)

* The vapor pressure for 1,1,2-trichloroethane is 22.49 mm Hg at 25 EC, and it has a log octanol/water partition coefficient (log K_ow) of 2.42. (1)

Uses

* 1,1,2-Trichloroethane is primarily used as a chemical intermediate in the production of 1,1-dichloroethene. It is also used as a solvent for chlorinated rubbers, fats, oils, waxes, and resins. (1)

Health Data from Inhalation Exposure

Concentration (mg/m³)	Health numbers^a	Regulatory, advisory numbers^b	Reference
10,000.0
_ _ _ _ 1,000.0	* LC₅₀ (rats) (9,024 mg/m³) * LC₅₀ (mice) (2,269 mg/m³)		1,2 1,2
_ _ _ _ 100.0
_ _ _ _ 10.0		* OSHA PEL and ACGIH TLV (46.4 mg/m³)	1
_ _ _ _ 1.0
_ _ _ _ 0.1
_ _ _ _ 0.01
_ _ _ _ 0.001
_ _ _ _ 0.0001
_ _ _ _ 0.00001	* EPA Cancer Risk Level^c (10^-6 excess lifetime risk) (6 H 10^-5 mg/m³)		3

See notes on following page.

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 effects.

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.

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.

^c These cancer risk estimates were derived from oral data and converted to provide the estimated inhalation risk.

References

1. Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for 1,1,2-Trichloroethane (Draft). U.S. Public Health Service, U.S. Department of Health and Human Services, Atlanta, GA. 1989.

2. 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.

3. U.S. Environmental Protection Agency. Integrated Risk Information System (IRIS) on 1,1,2-Trichloroethane. Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment, Office of Research and Development, Cincinnati, OH. 1993.

4. 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.

5. J.E. Amoore and E. Hautala. Odor as an aid to chemical safety: Odor thresholds compared with threshold limit values and volatilities for 214 industrial chemicals in air and water dilution. Journal of Applied Toxicology, 3(6):272-290. 1983.