Tetrachloroethylene

Tetrachloroethylene, also known as perchloroethylene or under the systematic name tetrachloroethene, and abbreviations such as perc, and PCE, is a chlorocarbon with the formula Cl2C=CCl2. It is a volatile, non-flammable, stable, colorless and dense liquid widely used for dry cleaning of fabrics and as a metal degreasing solvent, formerly as an oral anthelmintic. It has a mild, sweet, sharp odor, detectable by most people at a concentration of 50 ppm. Tetrachloroethylene is produced industrially by the chlorination or oxychlorination of hydrocarbons. Approximately a million tons of tetrachloroethylene are produced every year and the production amount is increasing every year, especially to be used in the production of HCFC and HFC refrigerants. It was first obtained from the thermal decomposition of hexachloroethane in 1820 by the English chemist-physicist Michael Faraday. Tetrachloroethylene is more stable compared to other chlorinated solvents and similar compounds as it does not react easily, does not tend to polymerize and has lower toxicity. Inhalation of vapours may affect the central nervous system, causing drowsiness, numbness, hallucinations and loss of consciousness. Exposure to high concentrations may irritate the skin and respiratory tract. It has been suspected of causing cancer in humans, but the evidence is limited. It was classified as "group 2A - probably carcinogenic" by the International Agency for Research on Cancer in 1995 due to sufficient evidence in some experimental animals and limited evidence for humans. The majority of studies investigating people exposed to tetrachloroethylene in the workplace and the environment have not found relation between tetrachloroethylene and human cancers. It is considered an industrial organic pollutant and has caused groundwater pollution in the past due to improper disposal. Its use has been restricted in some regions due to its environmental impacts and possible effects on human health, and alternatives are being explored in sectors such...