Tetrachloroethylene is a colorless liquid that is widely used today as a dry cleaning fluid and as a metal degreaser. In 1997, a total of 263,000 metric tons were used in the United States and Europe, potentially exposing more than 1.5 million workers. It is a common contaminant at the Superfund dump, as well as surface and ground water. PCE is volatile and about 85% of the PCE used each year is lost to the atmosphere, so it also becomes an air pollutant. Therefore, PCE is a very common potential occupational and environmental liver toxicant. Exposure occurs through inhalation, ingestion, and dermal pathways. Like TCE, the metabolism of PCE is extremely complex, with multiple competitive pathways leading to the formation of DCA and TCA.
Although PCE is considered relatively non-toxic, liver injury has been documented in human and animal models. Biopsy-confirmed liver disease has been documented in high occupational exposure Settings. Interestingly, chronic occupational PCE exposure appears to be associated with liver disease with normal liver enzyme levels. Liver enzymes were normal in 62% of the washermen who had been exposed to PCE, while only 39% of the washermen who had not been exposed to PCE had abnormal liver ultrasound results. Although pathologic confirmation was lacking, ultrasound findings were consistent with fatty liver. PCE is classified as 2A (probable) human carcinogen by IARC. PCE, like TCE, is a well – documented hepatocellular carcinogen in mice. However, liver tumors have not been documented in humans. Chronic inhalation studies conducted by NTP demonstrated benign (hepatocyte necrosis) and malignant liver disease.
Tetrachloroethylene is mainly used in dry cleaning industry and textile processing. It is also used as an insulating fluid in the production of fluorocarbons and, to a lesser extent, in adhesives, aerosols and paints. Most exposures occur through inhalation and skin contact as industrial contaminants. Liver damage, including cirrhosis, has been reported in workers exposed to low doses over a period of 2 to 6 years. There is a report on acute liver failure (ALF) associated with occupational use. Histological examination of the liver revealed extensive liver necrosis. Cases of hepatotoxicity due to unexpectedly high levels of exposure have also been reported. Tetrachloroethylene is carcinogenic to rodents.
