Dense nonaqueous phase liquids (dnapls)

Halogenated Alkenes

Trichloroethene

Human Health Toxicity

Trichloroethene (TCE) is used as a solvent, degreaser for metals, and as an intermediate in the synthesis of other chemicals. It also is used in the manufacture of electronic equipment and in a range of varnishes, paints, and adhesives. From the 1950s to the 1980s, TCE was used widely in obstetrics and dentistry as an inhalation anesthetic. The general public is exposed to TCE in ambient air, surface water, ground water, and drinking water. A survey conducted between 1981 and 1983 estimated that 401,373 employees were potentially exposed to TCE in the workplace.

The lung and gastrointestinal tract rapidly absorb TCE, and the circulatory system distributes it throughout the body. It concentrates in body fat and organ fat, such as that of the liver and brain. TCE generally metabolizes in the liver but a portion also is exhaled unchanged following both oral and inhalation exposure. As a lipophilic compound, TCE is predicted to be in breast milk where it could present a potential source of exposure to nursing infants.

Long-term animal studies employing dermal and inhalation routes of exposure indicate that among the non-cancer effects of the compound, the central nervous system is most sensitive to TCE. However, the liver and kidney are also affected.

Epidemiological studies indicate that the children of women exposed to TCE (and other degreasing solvents) have elevated risks for cardiac abnormalities. Neural tube defects also have been reported as a result of exposure to solvents (including TCE) in the workplace and in drinking water. Animal drinking water studies on the developmental effects of TCE indicate that TCE or its metabolites cause both cardiac and eye malformations. Other studies suggest that TCE affects the developing brain in rats. Several studies indicate that TCE may have a potentially adverse effect on the reproductive and endocrine systems of the human male.

TCE does not appear to be a potent genotoxicant, and in a number of standard tests, it has shown negative results for genotoxicity. However, the compound has produced some positive results, so it is not possible to completely rule out the possibility of genotoxicity.

EPA has characterized TCE as "carcinogenic to humans" by all routes of exposure and has found that TCE poses a potential human health hazard for non-cancer toxicity, including effects on the central nervous system, the kidney, the liver, the immune system, the male reproductive system, and the developing fetus. (EPA 2011).

---

Adapted from:

Toxicological Profile for Trichloroethylene (TCE)
Agency for Toxic Substances and Disease Registry (ATSDR)
Department of Health and Human Services, Atlanta, GA, 1997

Public Health Goal for Trichloroethylene in Drinking Water
Office of Environmental Health Hazard Assessment
California Environmental Protection Agency (CalEPA), 1999

Report on Carcinogens, Eleventh Edition
National Toxicology Program (NTP)
U.S. Department of Health and Human Services, 2002

Toxicological Review of Trichloroethylene (CAS No. 79-01-6) in Support of Summary Information on the Integrated Risk Information System (IRIS)
U.S. EPA, Office of Research & Development, Washington, DC.
EPA 635-R-09-011F, 1,200 pp, 2011

Trichloroethylene Health Risk Assessment: Synthesis and Characterization. External Review Draft
Office of Research and Development
U.S. EPA, EPA/600/P-01/002A, 2001

Ecological Toxicity

Although numerous studies exist on the effects of TCE in laboratory animals, no studies were located for terrestrial species of mammals, birds, or reptiles.

Some acute toxicity data are available for aquatic species. Median lethal concentrations (LC₅₀) values have been reported for grass shrimp (96 hr LC₅₀ 2 mg/L), medaka (24 hr LC₅₀ 440-730 mg/L), medaka (48 hr LC₅₀ 1.9 mg/L), sheepshead minnow (96 hr LC₅₀ 20 mg/L), bluegill sunfish (96 hr LC₅₀ 44.7 mg/L), fathead minnow (96 hr LC₅₀ 40.7 mg/L), and clawed toad 21-28 days after hatching (48 hr LC₅₀ 45 mg/L).

Human Health References

Public Health Goal for Trichloroethylene in Drinking Water
Office of Environmental Health Hazard Assessment
California Environmental Protection Agency (CalEPA), 1999

Report on Carcinogens, Eleventh Edition
National Toxicology Program (NTP)
U.S. Department of Health and Human Services, 2002

This three-page summary provides data on the carcinogenicity of TCE, its uses, properties, production and exposure.

Scope of the Risk Evaluation for Trichloroethylene
EPA 740-R-17-004, 66 pp, 2017

EPA presents the occupational scenarios in which workers and occupational non-users might be exposed to TCE during conditions of use, such as manufacturing, processing, repackaging, and recycling. EPA believes that workers and bystanders as well as certain other groups of individuals may experience greater exposures to TCE than the general population. The report is accompanied online by a separate extensive bibliography of literature concerning the chemical's fate, exposure, and environmental and human health hazards.

Toxicological Profile for Trichloroethylene (TCE)
Agency for Toxic Substances and Disease Registry (ATSDR)
Department of Health and Human Services, Atlanta, GA, 1997

2013 Addendum to the Toxicological Profile for Trichloroethylene

Toxicological Review of Trichloroethylene (CAS No. 79-01-6) in Support of Summary Information on the Integrated Risk Information System (IRIS)
U.S. EPA, Office of Research & Development, Washington, DC.
EPA 635-R-09-011F, 1,200 pp, 2011

Following U.S. EPA 2005 Guidelines for Carcinogen Risk Assessment, TCE is characterized as carcinogenic in humans by all routes of exposure. This conclusion is based on convincing evidence of a causal association between TCE exposure in humans and kidney cancer. The purpose of this toxicological review is to provide scientific support and rationale for the hazard and dose-response assessment in IRIS pertaining to chronic exposure to TCE; it is not intended to be a comprehensive treatise on the chemical or toxicological nature of TCE.

Trichloroethylene (TCE)
U.S. EPA, Health & Environmental Research Online (HERO).

In September 2011, EPA released the final health assessment for TCE to the IRIS database. The studies used in that assessment are listed in the HERO database. HERO is updated with newly published TCE toxicity studies as they are identified.

Trichloroethylene Health Risk Assessment: Synthesis and Characterization. External Review Draft
Office of Research and Development
U.S. EPA, EPA/600/P-01/002A, 2001

This 153-page draft document is a review of the health affects of TCE.

Ecological References

Environmental Contaminants Encyclopedia
Irwin, R.J., et al.
National Park Service, Water Resources Division, Fort Collins, CO, 1998

This web page provides information on human health effects, fate and transport, production, and uses of many chemicals including PCE.