Occupational and Environmental Hepatotoxicity

Tetrachloroethylene perchloroethylene [PCE] is a colorless liquid that is widely used today as a dry-cleaning fluid and for metal degreasing. A total 263,000 metric tons were used in the United States and Europe in 1997, and more than 1.5 million workers were potentially exposed.24 It is a common contaminant at Superfund waste sites and a surface water and groundwater pollutant. PCE is volatile, and approximately 85% of the PCE that is used annually is lost to the atmosphere, thus making it an airborne pollutant as well. Therefore PCE is an extremely common potential occupational and environmental hepatotoxicant. Exposures occur through inhalation, ingestion, and the dermal route. As with TCE, the metabolism of PCE is exceptionally complex, with multiple competing pathways leading to the formation of DCA and TCA.30

Although PCE is regarded as relatively nontoxic, hepatic injury has been documented in humans, as well as in animal models. Biopsy-proven liver disease has been documented in the setting of high occupational exposure.3 Interestingly, chronic occupational PCE exposure appears to be associated with liver disease with normal liver enzyme levels.3,30 Findings on hepatic ultrasound were abnormal in 62% of PCE-exposed laundry workers with normal liver enzymes versus only 39% of nonexposed laundry workers.31 Although pathologic confirmation was lacking, the ultrasound appearance was consistent with fatty liver.31 PCE is listed as a 2A (probable) human carcinogen by the IARC. Like TCE, PCE is a well-documented hepatocarcinogen in mice. However, liver tumors have not been documented in humans. Chronic inhalation studies conducted by the NTP demonstrated both benign (hepatocellular necrosis) and malignant liver disease

Tetrachloroethylene is used primarily in the dry cleaning industry and for textile processing. It is also used as an insulating fluid in the production of fluorocarbons and, to a lesser extent, in the production of adhesives, aerosols, and paint. Most exposure occurs through inhalation and dermal contact as an industrial contaminant. Liver injury, including cirrhosis, has been reported in workers with low-dose exposure over a 2–6-year period [104]. There has been one report of acute liver failure (ALF) associated with occupational use [105]. Histological examinations of the liver revealed massive hepatic necrosis. Cases of accidental high-level exposure resulting in hepatotoxicity have also been re