Toxicity Profiles

RAGs A Format for cis- and trans- 1,2-Dichloroethylene - CAS Numbers 156592 and 156605, respectively

1,2-Dichloroethylene, also called 1,2-dichloroethene, is a highly flammable, colorless liquid with a sharp, harsh odor. It is used to produce solvents and in chemical mixtures. Very small amounts of 1,2-dichloroethylene may be smelled in air (about 17 ppm). There are two forms of 1,2-dichloroethylene: cis-1,2-dichloroethylene and trans-1,2-di-chloroethylene. Sometimes both forms are present as a mixture. Commercial use is not extensive, but trans-1,2-dichloroethylene and mixtures of cis- and trans-1,2-dichloroethylene have been used as intermediates in the production of other chlorinated solvents and compounds, as well as low temperature extraction solvents for dyes, perfumes, and lacquers. Additionally, cis- and trans -1,2-dichloroethylene react violently with potassium hydroxide, sodium, and sodium hydroxide and form shock-sensitive explosives when combined with dinitrogen tetraoxide.

Humans are exposed to 1,2-dichloroethylene primarily by inhalation, but exposure can also occur by oral and dermal routes. Breathing high levels of 1,2-dichloroethylene can cause nauseous, drowsiness, and tiredness in humans; very high levels can cause death. Breathing high levels of trans-1,2-dichloroethylene caused liver and lung damage in animals, and the effects were more severe with longer exposure times. Animals that breathed very high levels of trans-1,2-dichloroethylene had damaged hearts. Animals that ingested extremely high doses of cis- or trans-1,2-dichloroethylene died. Lower doses of cis-1,2-dichloroethylene caused effects on the blood, such as decreased numbers of red blood cells and also effects on the liver.

No cancer bioassays or epidemiological studies were available to assess the carcinogenicity of 1,2-dichloroethylene. EPA has placed cis-1,2-dichloro-ethene in weight-of-evidence group D, not classifiable as to human carcinogenicity, based on the lack of or negative human or animal cancer data. Trans-1,2-dichloroethylene has not undergone a complete evaluation and determination under US EPA's IRIS program for evidence of human carcinogenic potential.

The following is a presentation of the toxicity information associated with 1,2-Dichloroethylene.

Cis-1,2-Dichloroethylene

Noncarcinogenic Health Effects
  • The Oral Chronic Reference Dose is 1.00E-02 (mg/kg-day).
  • The Oral Chronic Reference Dose has a modifying factor of 1.
  • The Oral Chronic Reference Dose has an uncertainty factor of 3000.
  • The Oral Chronic Reference Dose is based on the McCauley et al. rat study from 1995.
  • The Oral Chronic Reference Dose study target organ is blood.
  • The Oral Chronic Reference Dose study critical effect is decreased hematocrit.
  • The Oral Subchronic Reference Dose is 1.00E-01 (mg/kg-day).
  • The Oral Subchronic Reference Dose has a modifying factor of 1.
  • The Oral Subchronic Reference Dose has an uncertainty factor of 300.
  • The Oral Subchronic Reference Dose is based on the McCauley et al. rat study from 1995.
  • The Oral Subchronic Reference Dose study target organ is blood.
  • The Oral Subchronic Reference Dose study critical effect is decreased hematocrit.
  • The Dermal Chronic Reference Dose is 1.00E-02 (mg/kg-day).
  • The Dermal Chronic Reference Dose is based on a gastrointestinal absorption factor of 1.0000.

Trans-1,2-Dichloroethylene

Noncarcinogenic Health Effects
  • The Oral Chronic Reference Dose is 2.00E-02 (mg/kg-day).
  • The Oral Chronic Reference Dose has a modifying factor of 1.
  • The Oral Chronic Reference Dose has an uncertainty factor of 1000.
  • The Oral Chronic Reference Dose is based on the Barnes et al. study from 1985.
  • The Oral Chronic Reference Dose study critical effect is increased serum alkaline phosphatase in males.
  • The overall confidence in the Oral Chronic Reference Dose is low.

  • The Dermal Chronic Reference Dose is 2.00E-02 (mg/kg-day).
  • The Dermal Chronic Reference Dose is based on a gastrointestinal absorption factor of 1.0000.

  • The Inhalation Reference Concentration is 6.00E-02 (mg/kg-day).
  • The Inhalation Reference Concentration has a modifying factor of 1.
  • The Inhalation Reference Concentration has an uncertainty factor of 3000.
  • The Inhalation Reference Concentration is based on the Freundt et al. study from 1977.
  • The Inhalation Reference Concentration study critical effect is adverse effects i the liver (fatty degeneration) and lung (pulmonary capillary hyperemia and distension of the alveolar septum).
  • The overall confidence in the Inhalation Reference Concentration is low.

  • The Inhalation Chronic Reference Dose is calculated to be 1.7E-02 (mg/kg-day).

1,2-Dichloroethylene (Mixed Isomers)

Noncarcinogenic Health Effects

  • The Oral Chronic Reference Dose is 9.00E-03 (mg/kg-day).
  • The Oral Chronic Reference Dose has an uncertainty factor of 1000.
  • The Oral Chronic Reference Dose is based on the U.S. EPA study from 1991.
  • The Oral Chronic Reference Dose study target organ is liver.
  • The Oral Chronic Reference Dose study critical effect is lesions.
  • The Dermal Chronic Reference Dose is 7.20E-03 (mg/kg-day).
  • The Dermal Chronic Reference Dose is based on a gastrointestinal absorption factor of 0.8000.