U.S. EPA Contaminated Site Cleanup Information (CLU-IN)


U.S. Environmental Protection Agency
U.S. EPA Technology Innovation and Field Services Division

Dense Nonaqueous Phase Liquids (DNAPLs)

Chemistry and Behavior

Halogenated Alkanes

Ethanes

1,1,2-Trichloroethane

 1,1,2-Trichloroethane1,1,2-Trichloroethane (1,1,2-TCA, CAS# 79-00-5) has a vapor pressure of 22.49 mm Hg at 25oC (ATSDR 1989) and is a combustible liquid (NIOSH 2005). The log Koc of 1,1,2-TCA is estimated to be 1.06-2.49, the log Kow is 2.42, and the Henry's constant is 9.1 e-4 atm-m3/mol at 25oC. The solubility of 1,1,2-TCA is about 4,400 mg/L at 20oC (ATSDR 1989), and its specific gravity is about 1.44 (20oC). The Agency for Toxic Substances and Disease Registry's toxicological profile for 1,1,2-TCA contains a useful summary tableAdobe PDF Logo of its physical properties.

The relatively low calculated Koc value for 1,1,2-TCA in soil indicates that the compound is likely to move quickly through soil and sediment (ATSDR 1989 and HSDB).

Based on a Henry's law constant of 2.03 e-3 atm-m3/mol at 20oC, 1,1,2-TCA is expected to volatilize rapidly from water surfaces (ATSDR 1989). Modeling information in the Hazardous Substances Data Bank record for 1,1,2-TCA suggests that its half life in a model river is about two hours, and about five days in a model lake (HSDB).

Because of the low Kow of 1,1,2-TCA, bioaccumulation is expected to be low, and there should be no biomagnification (ATSDR 1989). Microbial degradation of the compound occurs primarily under anaerobic conditions (ATSDR 1989 and HSDB). 1,1,2-TCA may undergo hydrolysis, but the process is slow (ATSDR 1989).

When released to the atmosphere, hydroxyl radicals are expected to degrade 1,1,2-TCA with a half life of about 49 days (ATSDR 1989). Direct photolysis is not expected to occur (HSDB). Due to its relatively long atmospheric lifetime, 1,1,2-TCA can be widely dispersed, but it is not expected to accumulate in the atmosphere (ATSDR 1989).

References

1,1,2-Trichloroethane, CASRN: 79-00-5
Hazardous Substances Data Bank (HSDB)
National Library of Medicine Web site.

1,1,2-Trichloroethane
NIOSH Pocket Guide to Chemical Hazards.
National Institute of Occupational Safety and Health, NIOSH Publication Number 2005-149, 2005

Toxicological Profile for 1,1,2-Trichloroethane
Agency for Toxic Substances and Disease Registry (ATSDR), 120 pp, 1989

For Further Information

Degradation of 1,1,2,2-Tetrachloroethane and Accumulation of Vinyl Chloride in Wetland Sediment Microcosms and In Situ Porewater: Biogeochemical Controls and Associations with Microbial Communities
Lorah, M.M. and M.A. Voytek.
Journal of Contaminant Hydrology 70(1-2):117-145(2004)
View abstract

This paper investigates the degradation of 1,1,2,2-tetrachloroethane and 1,1,2-TCA under different anaerobic conditions.

DNAPL Site Evaluation Adobe PDF Logo
Cohen, R. and J. Mercer.
EPA 600-R-93-022, 369 pp, 1993

This document has a broad discussion of DNAPL site evaluation and contains a comprehensive table of physical properties of selected DNAPL chemicals, including 1,1,2-TCA, in its Appendix A.