Dense nonaqueous phase liquids (dnapls)

Halogenated Alkenes

Tetrachloroethene

Human Health Toxicity

Tetrachoroethene (PCE) is used in dry cleaning clothes and other textiles and degreasing metal. It is used as a solvent for inks, paint removers, and adhesives, and as an intermediate in the production of other chemicals. It also is used in the electronics industry. PCE is volatile and readily evaporates during use.

In addition to occupational exposures to PCE, the general population is likely to be exposed to the compound. It is detectable in outdoor air at concentrations generally below 1-2 µg/m³ and at higher concentrations (median value 4 µg/m³) in indoor air. PCE may be present in drinking water and ground water. An estimate for the mean daily intake of PCE is 0.5-3 µg/kg body weight per day.

PCE is readily absorbed following inhalation or oral exposure, and lesser quantities may be absorbed via the skin. Absorbed PCE is distributed to fat tissue, with comparatively small amounts distributed to the brain, kidneys, lungs, and liver. Most of the absorbed compound is excreted chemically unchanged in exhaled air. However, metabolism of PCE takes place in the liver and its metabolites are excreted in urine.

Fish studies indicate a low potential for PCE to bioaccumulate.

Repeated exposure of laboratory animals to PCE showed that the liver, kidney, and central nervous systems are target organs for toxicity. Species differences were observed in response to PCE, with greater liver toxicity in mice than in rats. Long-term (chronic) studies have determined that PCE is carcinogenic in laboratory animals by both inhalation and oral exposure routes. Leukemia and malignant kidney tumors were seen in rats following inhalation exposure. Liver tumors developed in mice after oral and inhalation exposure. Benign tumors of the Harderian gland (a structure associated with the lachrymal glands of the eye) appeared in mice following inhalation of PCE. A weight-of-evidence approach suggests that PCE is not significantly genotoxic in vivo. In vitro testing does not indicate that PCE is genotoxic, although mammalian metabolites of the compound show mutagenic activity in Ames tests.

Developmental and reproductive studies in laboratory animals suggest that PCE is toxic to the fetus at doses that are also toxic to the mother. No evidence of structural deformities was seen in the young of pregnant rats and rabbits exposed to PCE, but a mouse study reported soft tissue malformations in the offspring at doses that were maternally toxic. Offspring of rats and mice whose dams were exposed to PCE in pregnancy showed slight changes in the central nervous system, including the neurochemistry.

Women exposed to PCE in the workplace have shown increased risks of spontaneous abortion, according to some epidemiological studies. Not enough information exists to conclude whether PCE has other adverse reproductive effects, such as fetal deformities or reduced fertility.

Occupational studies of exposed workers suggest that inhaled PCE is toxic to the central nervous system and to the kidney. The neurotoxic effects of PCE exposure were demonstrated by deficits in behavioral tests. Injuries to both the glomerular and tubular areas of the kidney were reported.

Evidence of carcinogenicity in workers exposed to PCE is limited. Existing studies do not provide good information on the levels of worker exposure to PCE or to previous occupational exposures to other solvents. Elevated mortality for dry cleaning workers has been reported with an increased incidence of cancers of the esophagus and uterine cervix. Some studies reported excess cases of non-Hodgkins lymphoma, but these excesses were not statistically significant. Exposure to PCE in drinking water does not appear to increase the risk of total or specific cancers for the general population as determined by general population and case-control studies.

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Adapted from:

Concise International Chemical Assessment Document (#68) Tetrachloroethene
International Programme on Chemical Safety (IPCS), 2006

Ecological Toxicity

Aquatic invertebrates are affected by the addition of PCE to their environment. For example, in a study using an experimental pond system, some species, such as rotifers, first increased in number, then entirely disappeared later in the study. Fish appear to be sensitive to PCE, and rainbow trout have a 96-hr median lethal concentration (LC₅₀) of 5 mg/L. One study of the Japanese medaka has shown that 1.5 mg/L PCE will reduce hatching and induce a significant number of developmental effects, including abnormal development of the heart and circulatory system, pericardial edema, hemorrhage, and scoliosis.

The 14-day LC₅₀ for earthworms is in the range of 100-320 mg/kg. No studies of terrestrial mammals are available. Terrestrial plants are affected when PCE is added to water in a hydroponic cultivation system; no increase in the mass of hybrid polar cuttings was observed after two weeks of continuous exposure to 45 mg/L PCE.

Human Health References

Concise International Chemical Assessment Document (#68) Tetrachloroethene
International Programme on Chemical Safety (IPCS), 2006

This document is a comprehensive review of the physical/chemistry properties, fate and transport, human and ecological health effects, and occurrence of PCE.

Review of the Environmental Protection Agency's Draft IRIS Assessment of Tetrachloroethylene
National Research Council, Board on Environmental Studies and Toxicology.
National Academies Press, Washington, DC. ISBN-10: 0-309-15094-9, 174 pp, 2010

The June 2008 EPA assessment of PCE reviewed by the National Research Council Committee found that existing (and already protective) standards for PCE exposure, particularly for the inhalation pathway, were not sufficiently protective. The committee identified concerns about some of the approaches that EPA used to evaluate the data on PCE, as well as several parts of the draft IRIS assessment that could be improved on in the future. The report also documents divisions about the assessment among the committee members, including an unusual dissenting statement and rebuttal.

Scope of the Risk Evaluation for Perchloroethylene (Ethene, 1,1,2,2-Tetrachloro)
EPA 740-R-17-007, 77 pp, 2017

EPA presents the occupational scenarios in which workers and occupational non-users might be exposed to PCE 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 PCE 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.

Search for Tetrachloroethylene in EPA's Substance Registry System
Substance Registry System
U.S. EPA, 2006

A database maintained by EPA that provides synonyms and some physical chemical data but is mostly devoted to providing links to regulatory resources and toxicological databases.

Tetrachloroethylene (Perc, or PCE)
U.S. EPA, Health & Environmental Research Online (HERO).

In February 2012, EPA released the final health assessment for PCE to the IRIS database. The studies used in that assessment are listed in the HERO database. HERO is updated with newly published PCE toxicity studies as they are identified.

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

This profile provides information on human health effects, fate and transport, production, and uses of PCE.

Toxicological Review of Tetrachloroethylene (Perchloroethylene) (CAS NO. 127-18-4) in Support of Summary Information on the Integrated Risk Information System (IRIS)
U.S. EPA, Washington, DC. EPA 635-R-08-011F, 1077 pp, 2012

This toxicological review presents the scientific support and rationale for the hazard and dose-response assessment in IRIS pertaining to chronic exposure to PCE. This assessment replaces the 1988 IRIS assessment for PCE and for the first time includes a hazard characterization for cancer effects. The assessment is not intended to be a comprehensive treatise on PCE's chemical or toxicological nature.

Toxicology and Carcinogenesis Studies of Tetrachloroethylene (Perchloroethylene) (CAS No. 127-18-4) in F344/N Rats and B6C3F₁ Mice (Inhalation Studies) TR 311.
National Toxicology Program, 1986
(Abstract)

Ecological References

Concise International Chemical Assessment Document (#68) Tetrachloroethene
International Programme on Chemical Safety (IPCS), 2006

This document is a comprehensive review of the physical/chemistry properties, fate and transport, human and ecological health effects, and occurrence of PCE.

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.