Toxicity Profiles

RAGs A Format for Trichloroethene - CAS Number 79016

Trichloroethene (TCE), also known as trichlorothylene, is a colorless, highly volatile liquid that is miscible with water and a number of organic solvents. TCE is a man-made chemical and is not known to occur naturally. It is mainly used as a solvent in industrial degreasing and cleaning of metals, but it is also used as a solvent for waxes, fats, resins, oils, and in numerous other applications. Prior to 1977, TCE had been used as an anesthetic, grain fumigant, disinfectant, and extractant of spice oleoresins in food and of caffeine in the production of decaffeinated coffee. The evaluation of the toxicity of TCE is complicated by the presence or absence of other chemicals. Industrial grade TCE usually contains stabilizers that are known to be toxic such as triethylamine, triethanolamine, epichlorohydrin, or stearates. In the absence of stabilizers, TCE readily decomposes. These decomposition products are also toxic.

Human and animal data indicate that exposure to TCE can result in toxic effects on a number of organs and systems, including the liver, kidney, blood, skin, immune system, reproductive system, nervous system, and cardiovascular system. Breathing small amounts of TCE may cause headaches, lung irritation, dizziness, poor coordination, and difficulty concentrating. Breathing large amounts of TCE may cause impaired heart function, unconsciousness, and death. Breathing it for long periods may cause nerve, kidney, and liver damage. Drinking large amounts of TCE may cause nausea, liver damage, unconsciousness, impaired heart function, or death. Drinking small amounts of TCE for long periods may cause liver and kidney damage, impaired immune system function, and impaired fetal development in pregnant women, although the extent of some of these effects is not yet clear. Skin contact with TCE for short periods may cause skin rashes.

Epidemiologic studies have been inadequate to determine if a correlation exists between exposure to TCE and increased cancer risk in humans. Some human studies with exposure over long periods to high levels of TCE in drinking water or in workplace air have found evidence of increased cancer; however, these results are inconclusive because the cancer could have been caused by other chemicals. Some studies with mice and rats have suggested that high levels of TCE may cause liver or lung cancer. Although U.S. EPA's Science Advisory Board recommended a weight-of-evidence classification of C-B2 continuum (C = possible human carcinogen; B2 = probable human carcinogen), the agency has not adopted a current position on the weight-of-evidence classification. In an earlier evaluation, TCE was assigned to weight-of-evidence Group B2, probable human carcinogen. The International Agency for Research on Cancer (IARC) has determined that TCE is not classifiable as to human carcinogenicity.

The following is a presentation of the toxicity information associated with Trichloroethene.

• The Oral Chronic Reference Dose is 3.00E-04 (mg/kg-day) based on critical effects in the liver, kidney, and developing fetus.

• The Dermal Chronic Reference Dose is 4.50E-05 (mg/kg-day).
• The Dermal Chronic Reference Dose is based on a gastrointestinal absorption factor of 0.1500.

• The Inhalation Chronic Reference Concentration is 4.00E-02 (mg/m³) based on critical effects in the central nervous system, liver, and endocrine system.
• The Inhalation Chronic Reference Dose is 1.14E-02 (mg/kg-day).

• The Oral Slope Factor is 4.00E-01 (mg/kg-day)^-1.

• The Inhalation Slope Factor is 4.00E-01 (mg/kg-day)^-1.

• The Dermal Slope Factor is 2.67E+00 (mg/kg-day)^-1.
• The Dermal Slope Factor is based on a gastrointestinal absorption factor of 0.1500.