Trichloroethylene, commonly called TCE, is a synthetic chemical primarily used as an industrial degreasing solvent and as a raw material for manufacturing refrigerants. As of 2004, roughly 73% of all TCE consumed in the United States went toward producing the refrigerant HFC-134a, while 24% was used for metal degreasing. The remaining 3% covered a range of smaller applications. However, the EPA finalized a rule in December 2024 that will prohibit virtually all manufacturing, processing, and use of TCE due to its cancer risk.
Metal Degreasing and Industrial Cleaning
TCE’s best-known use is vapor degreasing, a process for removing oils, greases, and other residues from metal and composite parts. The process works by heating liquid TCE inside a degreasing unit until it becomes a hot vapor. When metal parts are lowered into the unit, the vapor condenses on their cooler surfaces, forming droplets that bead up and drip off, carrying contaminants away and leaving a clean surface behind. This method is fast, effective, and doesn’t require scrubbing or water rinsing, which made it a staple in manufacturing for decades.
Vapor degreasing with TCE has been common in metal plating, electronics assembly, part fabrication, and automotive and aerospace repair shops. It was also used by dry cleaners to remove stains from fabrics. Beyond industrial degreasing, TCE showed up in a surprisingly wide range of consumer and commercial products: brake cleaners, sealants, lubricants, adhesives, paints and coatings, furniture care products, and even arts and crafts spray coatings designed to protect finished prints or artwork.
Refrigerant Manufacturing
The single largest use of TCE in the United States has been as a chemical feedstock, meaning it serves as a starting ingredient in the production of another chemical. Specifically, TCE is converted into HFC-134a, a refrigerant introduced in the 1990s as a replacement for CFC-12, which was phased out because it damaged the ozone layer. Global demand for HFC-134a drove strong U.S. exports of TCE for years and kept production volumes high even as degreasing applications declined. By 2004, this feedstock use accounted for nearly three-quarters of all domestic TCE consumption.
Historical Uses in Medicine and Food
TCE had a surprisingly broad role in medicine and food processing before its health risks were fully understood. During the 1950s and 1960s, it was used as an anesthetic in hospitals, particularly for women during childbirth. It also served as a surgical disinfectant and was prescribed to treat migraines and trigeminal neuralgia, a nerve disorder that causes severe facial pain.
In the food industry, TCE was used to extract vegetable oils and spices and to remove caffeine from coffee beans in the production of decaffeinated coffee. It was also applied as a grain fumigant and added to pet food as a processing agent. All food and medical uses were banned in 1977.
Why TCE Is Being Phased Out
The EPA classifies TCE as “carcinogenic to humans” by all routes of exposure, including breathing it, touching it, and ingesting it. The cancers most strongly linked to TCE are kidney cancer (renal cell carcinoma), non-Hodgkin’s lymphoma, and liver tumors. These findings are not based on animal studies alone; human epidemiological data supports the link.
Beyond cancer, TCE is one of the most common groundwater contaminants at Superfund cleanup sites across the country. When TCE seeps into soil and groundwater from old industrial sites, it can evaporate from the contaminated ground and rise as vapor into homes, schools, and workplaces through cracks in foundations. This process, called vapor intrusion, means people can be exposed to TCE without knowing it and without any way to avoid it unless a mitigation system is installed. The EPA’s drinking water standard for TCE is 5 parts per billion, with a health goal of zero.
The 2024 Federal Ban
In December 2024, the EPA finalized a rule under the Toxic Substances Control Act that effectively ends the commercial life of TCE in the United States. The rule prohibits the manufacture (including import), processing, and distribution of TCE for all uses. Industrial and commercial use of TCE is also prohibited, though a small number of critical uses receive longer compliance timeframes or time-limited exemptions. The rule even bans disposing of TCE into public or industrial wastewater treatment systems. Most of these prohibitions take effect within one year.
For workers still in contact with TCE during any remaining transition period, OSHA’s current permissible exposure limit is 100 parts per million as a time-weighted average over a work shift, with a ceiling of 200 ppm. The National Institute for Occupational Safety and Health recommends a much stricter limit of 25 ppm and considers TCE a potential occupational carcinogen.