Until recent years, the US Agency for Toxic Substances and Disease Registry (ATSDR) contended that trichloroethylene had little-to-no carcinogenic potential and was probably a co-carcinogen—that is, it acted in concert with other substances to promote the formation of tumors.
State, federal, and international agencies classify trichloroethylene as a known or probable carcinogen. In 2014, the International Agency for Research on Cancer updated its classification of trichloroethylene to Group 1, indicating that sufficient evidence exists that it causes cancer of the kidney in humans as well as some evidence of cancer of the liver and non-Hodgkin's lymphoma.
In the European Union, the Scientific Committee on Occupational Exposure Limit Values (SCOEL) recommends an exposure limit for workers exposed to trichloroethylene of 10 ppm (54.7 mg/m) for 8-hour TWA and of 30 ppm (164.1 mg/m) for STEL (15 minutes).
Existing EU legislation aimed at protection of workers against risks to their health (including Chemical Agents Directive 98/24/EC and Carcinogens Directive 2004/37/EC) currently do not impose binding minimum requirements for controlling risks to workers' health during the use phase or throughout the life cycle of trichloroethylene.
In 2023, the United States EPA determined that trichloroethylene presents an unreasonable risk of injury to human health under 52 out of 54 conditions of use, including during manufacturing, processing, mixing, recycling, vapor degreasing, as a lubricant, adhesive, sealant, cleaning product, and spray. It is dangerous from both inhalation and dermal exposure and was most strongly associated with immunosuppressive effects for acute exposure, as well as autoimmune effects for chronic exposures. As of June 1, 2023, two U.S. states (Minnesota and New York) have acted on the EPA's findings and banned trichloroethylene in all cases but research and development. According to the US EPA, in October 2023 it "proposed to ban the manufacture (including import), processing, and distribution in commerce of TCE for all uses, with longer compliance time frames and workplace controls (including an exposure limit) for some processing and industrial and commercial uses until the prohibitions come into effect" to protect everyone including bystanders from the harmful health effects of TCE.