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