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cis-1,2-dichloroethylene Structural Formula
cis-1,2-dichloroethylene Structural Formula
CAS Number: 156-59-2
Synonyms: cis-1,2-dichloroethene
Contaminant Type: Chemical

Cis-1,2-dichloroethylene is one of two forms of 1,2-dichloroethylene (also called 1,2-dichloroethene). The other form is trans-1,2-dichloroethylene. Cis-1,2-dichloroethylene is a highly flammable, colorless liquid with a sharp, harsh odor. The most frequent uses of 1,2-Dichloroethene are solvent production and chemical mixtures [2300]. U.S. production estimates are available for 1994 (between 10,000 pounds and 0.5 million pounds) [2312].

1,2-Dichloroethene enters the environment through industrial activity, including releases from manufacturers who make or use 1,2-dichloroethylene, landfills, hazardous waste sites, chemical spills, burning of objects made of vinyl, and breakdown of other chlorinated chemicals (2300). This chemical has been found in air, water, and soil.

Regardless of where a surface release of cis-1,2-dichloroethene occurs, rapid evaporation is likely to occur. In the air, it has a half-life of 5 to 12 days because reactions with radicals degrade cis-1,2-dichloroethylene. Subsurface releases of 1,2-dichloroethene (e.g., in landfills or hazardous waste sites) can result in groundwater contamination if water dissolves 1,2-dichloroethylene and transports it to an aquifer. In groundwater, the half-life is 13 to 48 weeks. For underground releases, it is possible for the 1,2-dichloroethene to eventually break down into vinyl chloride.

For cis-1,2-dichloroethylene, the maximum contaminant level (MCL) set by USEPA is 0.07 ppm, which equals the maximum contaminant level goal (MCLG). USEPA has identified packed tower aeration and granular activated carbon as best available technologies capable of removing volatile organic compounds from water to their respective MCLs. Additional small system compliance technologies are diffused aeration, multi-stage bubble aeration, tray aeration, and shallow tray aeration [2302]. Long-term exposure to cis-1,2-dichlrorethylene has been linked to increased kidney weight in animals [2314].

2300 Agency for Toxic Substances and Disease Registry; 1996; Toxicological Profile for 1,2-Dichlorethene; http://www.atsdr.cdc.gov/toxprofiles/tp87.pdf; Most recent ATSDR profile; includes cis-1,2-dichloroethene and trans-1,2-dichloroethene information
2312 National Center for Biotechnology Information; 2015; PubChem Compound Database; CID=643833; http://pubchem.ncbi.nlm.nih.gov/compound/643833; accessed June 4, 2015
2314 Integrated Risk Information System; 2010; IRIS Summary for cis-1,2-Dichloroethylene; U.S. EPA, Office of Research and Development, National Center for Environmental Assessment; http://www.epa.gov/iris/subst/0418.htm

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