What is 1,2-DCE and how is it used?

1,2-Dichloroethylene (1,2-DCE) is an odorless organic liquid that has two slightly different forms, a "cis" form and a "trans" form. Both the cis and trans forms - usually as a mixture - are used as a solvent for waxes and resins; in the extraction of rubber; as a refrigerant; in the manufacture of pharmaceuticals and artificial pearls; in the extraction of oils and fats from fish and meat; and in making other organics.

Trade Names and Synonyms:
1,2-DCE or Acetylene dichloride

Why is 1,2-DCE being Regulated?
In 1974, Congress passed the Safe Drinking Water Act. This law requires the EPA to determine safe levels of chemicals in drinking water which actually cause health problems, or MIGHT cause health problems. These non-enforceable levels, based solely on possible health risks and exposure, are called Maximum Contaminant Level Goals (MCLG's).

The MCLGs for 1,2-DCE have been set at 0.07 parts per million (ppm) for the cis form, and 0.1 ppm for the trans form. The EPA believes this level of protection would not cause any of the potential health problems described below.

Based on this MCLG, the EPA has set an enforceable standard called a Maximum Contaminant Level (MCL). MCLs are set as close to the MCLGs as possible, considering the ability of public water systems to detect and remove contaminants using suitable treatment technologies.

Like the MCLG's, the MCLs have also been set at 0.07 ppm for the cis form, and 0.1 ppm for the trans form. The EPA believes, given present technology and resources, this is the lowest level to which water systems can reasonably be required to remove this contaminant should it occur in drinking water.

These drinking water standards and the regulations for ensuring these standards are met, are called National Primary Drinking Water Regulations. All public water supplies must abide by these regulations.

What are the Health Effects?
Short-term: EPA has found both forms of 1,2-DCE to potentially cause central nervous system depression when people are exposed to it at levels above the MCL for relatively short periods of time.

Long-term: Both forms have the potential to cause liver, circulatory and nervous system damage from long-term exposure at levels above the MCL. The trans form is approximately twice as potent as the cis form in its ability to depress the central nervous system.

How much 1,2-DCE is produced and released to the environment?
Releases to the environment are expected to be limited to manufacturing plants in the Gulf Region of the United States. Since neither form is a listed chemical in the Toxics Release Inventory, data on releases during manufacture and handling are not available.

Trans-1,2-DCE may be released to the environment in air emissions and wastewater during its production and use as a solvent and extractant. It may also be released in organic synthesis, in the manufacture of perfumes, lacquers, and thermoplastics.

What happens to it when it is released to the environment?
If either form released on soil, it should evaporate and leach into the groundwater where it will break down very slowly. If released to water, it will mainly evaporate. Neither of the two forms of this contaminant is likely to accumulate in aquatic life