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-Dichloroethane

1,1-Dichloroethane 1,1-Dichloroethane (1,1-DCA, CAS# 75-34-3) is a colorless, oily, synthetic liquid. It is a Class IB Flammable Liquid (NIOSH 2005). 1,1-DCA is volatile with a vapor pressure of 230 mm Hg at 25oC, and it does not dissolve easily in water with a solubility of 5,500 mg/L at 20oC. The log Kow is 1.79, the log Koc is 1.76, and the Henry's Law constant is 4.2 e-2 atm-m3/mole (ATSDR 1990).

Once released to the atmosphere, 1,1-DCA can be transported long distances before being washed out in precipitation. Because of the low aqueous solubility and high volatility, physical removal through rainfall is not the main source for downwind concentrations, which are attributed mainly to aerial transport. Hydroxyl radicals react to oxidize 1,1-DCA, and the half life in the atmosphere is estimated to be 44 days (ATSDR 1990).

When released to land surfaces from spills or leaks, the compound would volatilize rapidly to the atmosphere; however, 1,1-DCA remaining on soil surfaces would transport into groundwater. Its low Koc value suggests that it would not sorb well to soils with low organic content (ATSDR 1990).

The evaporation half-life of 1,1-DCA has been estimated to be approximately 1 day for river water and more than 6 days for pond water (ATSDR 1990).

1,1-DCA is not expected to bioconcentrate in organisms because of its low Kow value (ATSDR 1990). The compound can be slowly degraded anaerobically to chloroethane and ethane (Chen et al. 1999); however, depending upon the site, this process has the potential to stall at chloroethane (Ferris, et al. 2006, Best 1999, Grostern and Edwards 2006). 1,1-DCA can be degraded aerobically by cometabolic mechanisms but is aerobically recalcitrant (Field and Sierra-Alvarez 2004).

References

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

A 1,1,1-Trichloroethane-Degrading Anaerobic Mixed Microbial Culture Enhances Biotransformation of Mixtures of Chlorinated Ethenes and Ethanes
Grostern, A. and E.A. Edwards.
Applied and Environmental Microbiology 72(12):7849-7856(2006)

This experiment showed that 1,1-dichloroethane is degraded to chloroethane under anaerobic conditions but that it can stall at chloroethane at some sites. View longer abstract

Anaerobic Transformation of 1,1,1-Trichloroethane by Municipal Digester Sludge
Chen, C., B. Ballapragada, J. Puhakka, S. Strand, and J. Ferguson.
Biodegradation 10(4):297-305(1999)
View abstract

Adobe PDF LogoAnaerobic Transformation of Chlorinated Hydrocarbons in a Packed-Bed Reactor
Best, Jappe Hinco de, Ph.D. dissertation, University of Groningen, 138 pp, 1999

Adobe PDF LogoBiodegradability of Chlorinated Solvents and Related Chlorinated Aliphatic Compounds
Field, J.A. and R. Sierra-Alvarez.
Euro Chlor, 98 pp, 2004

Pilot Test Evaluation for Enhanced Anaerobic Bioremediation of Chlorinated EthanesAdobe PDF Logo
Ferris, S., B. Henry, C. Coker, and R. Lantzy.
Proceedings of the Fifth International Conference on Remediation of Chlorinated and Recalcitrant Compounds (Monterey, CA; May 2006)

Toxicological Profile for 1,1-DichloroethaneAdobe PDF Logo
Agency for Toxic Substances and Disease Registry (ATSDR), 116 pp, 1990