Trichloroethylene (TCE)

Because of pervasiveness of TCE in the environment, most people are exposed to low levels of TCE. The general U.S. population is exposed via inhalation, ingestion, or dermal pathways. The most important pathways appear to be inhalation of contaminated ambient air and ingestion of contaminated drinking water. Consumers are exposed through their use of wood stains, varnishes, finishes, lubricants, adhesives, typewriter correction fluid, paint removers, and cleaners that contain TCE. Occupational exposure results primarily from use of TCE as a degreasing or metal cleaning agent; workers in the vapor degreasing industry are exposed to the highest levels through inhalation. Elevated exposure might occur to people living near waste facilities, those being exposed through occupational activities, and residents of some urban and industrial areas where TCE-contaminated media occur. TCE has been detected in breast milk, hence nursing infants may be exposed via this pathway. TCE does not accumulate or build up in the cells of plants or animals, so it typically is not found in the food chain. For most people, the level of exposure to TCE through food, beverages, or drinking water is very low.

The health effects from TCE vary depending on the amount of TCE to which a person is exposed and how long the exposure lasts. Levels of TCE in the normal environment generally are well below levels of those in the workplace. Health effects similar to those described below are unlikely to be observed in the general public. Dizziness, headache, slowed reaction time, sleepiness, and facial numbness have occurred in workers breathing TCE or in people who use TCE-containing products in small, poorly ventilated areas; concentrations causing these effects are higher than the allowable occupational exposure level. Irritation of the eyes, nose, and throat also occur under these conditions. In general, the effects that result from one or several exposures to TCE disappear when exposure ends. 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).

Studies in animals show that ingesting or breathing levels of TCE that are higher than typical environmental levels can produce nervous system changes; liver and kidney damage; effects on the blood; tumors of the liver, kidney, lung, and male sex organs; and possibly cancer of the tissues that form the white blood cells (leukemia).

Human Health

Assessing the Human Health Risks of Trichloroethylene: Key Scientific Issues
Committee on Human Health Risks of Trichloroethylene, National Research Council, 472 pp, 2006.

Chronic Toxicity Summary: Trichloroethylene
California Office of Environmental Health Hazard Assessment, 8 pp, 1999.

Consumer Fact Sheet on: Trichloroethylene
U.S. EPA, Office of Water.

Examination of Risk-Based Screening Values and Approaches of Selected States
Interstate Technology and Regulatory Council (ITRC). RISK-1, 115 pp, 2005.

Screening values for a specific chemical may vary among states and even among different regions of EPA. The ITRC Risk Team examined and documented the screening values for five specific contaminants�arsenic, benzo(a)pyrene, lead, polychlorinated biphenyls, and trichloroethene�that are often identified as drivers for management actions at contaminated sites.

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.

Sources, Emission and Exposure for Trichloroethylene (TCE) and Related Chemicals
U.S. EPA, Office of Research and Development, National Center for Environmental
Assessment, Washington, DC. EPA 600-R-00-099, 138 pp, Mar 2001.

TCE Issue Papers
U.S. EPA, National Center for Environmental Assessment, 2006.

These documents were prepared to provide an overview of recent studies with bearing on different aspects of TCE risk assessment in support of the National Research Council committee's review of EPA's 2001 draft TCE health risk assessment report. The issue papers summarize and outline some of the recently published scientific literature but are not intended to provide a complete survey and synthesis of the literature.

TCE Issue Paper 1: Issues in Trichloroethylene Pharmacokinetics

TCE Issue Paper 2: Interactions of Trichloroethylene, Its Metabolites, and Other Chemical Exposures

TCE Issue Paper 3: Role of Peroxisome Proliferator-Activated Receptor Agonism and Cell Signaling in Trichloroethylene Toxicity

TCE Issue Paper 4: Issues in Trichloroethylene Cancer Epidemiology

ToxFAQs™ for Trichloroethylene (TCE)
Agency for Toxic Substances and Disease Registry, 2003.

Toxicological Profile for Trichloroethylene (TCE)
Agency for Toxic Substances and Disease Registry (ATSDR), 2019.

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.

TSCA Work Plan, Chemical Risk Assessment, Trichloroethylene: Degreasing, Spot Cleaning and Arts & Crafts Uses
U.S. EPA, Office of Chemical Safety and Pollution Prevention.
EPA Document# 740-R1-4002, 212 pp, 2014

This risk assessment focused on uses of TCE as a degreaser both in small commercial settings and by consumers, such as commercial use of TCE as a spotting agent in dry cleaning shops and consumer use of TCE in a clear protective coating spray by individuals in the arts/crafts field. The assessment encompassed adults of both sexes, ages 16 and older, for both primary users (including pregnant women) and bystanders.

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
U.S. EPA, Office of Research and Development.
EPA 600-P-01-002A, 153 pp, 2001.

Review of Draft Trichloroethylene Health Risk Assessment: Synthesis and Characterization: An EPA Science Advisory Board Report
U.S. EPA Science Advisory Board (SAB), Environmental Health Committee, TCE Review Panel.
EPA-SAB-EHC-03-002, 83 pp, Dec 2002.

Ecological Impacts

Trichloroethylene (Trichloroethene, TCE, CAS number 79-01-6)
In Environmental Contaminants Encyclopedia, R.J. Irwin, M. VanMouwerik, L. Stevens, M.D.
Seese, and W. Basham (compilers).
National Park Service, Water Resources Division, Fort Collins, CO. 43 pp, 1997.
Contact: Roy Irwin, roy_irwin@nps.gov