In the 1960s, tetrachlorethylene (TCE), also known as perchlorethylene, became the organic solvent of choice for dry cleaners1. About half of the TCE produced in the United States in 1990 was used for dry cleaning and in the Nordic countries TCE use reached its peak around 1970 when it was the main dry cleaning solvent1, 2. The National Institute for Occupational Safety and Health (NIOSH) estimated that in the early 1980s, approximately 500,000 dry cleaners may have been exposed to TCE3. From the early 1970s to the 1980s, the incidence of primary liver cancer increased in several countries4. Over the years, the association between TCE and liver cancer has not been consistent between human epidemiological studies and associations observed in animal experiments4. Motivated by inconsistencies in prior literature and animal experimental evidence, this article reviews published epidemiologic studies reporting findings on tetrachlorethylene exposure and human liver cancer. ResultsTwo case-control studies4,5, two nested case-control studies2,6 and two cohort studies1,7 reported estimates. for the association between tetrachlorethylene (TCE) exposure and primary liver cancer. A non-significant association was found between occupational solvent exposure and primary liver cancer in one case-control study, while the other observed a significant association. Hemberg et al. found that the odds ratio (OR) for high/moderate exposure versus low/no exposure was 2.3 (95% CI: 0.8, 7.0). The association was restricted to women (Fisher's exact chi-square p = 0.007), with men having a non-significant odds ratio of 0.5. Stemhagen et al. found that among men, the OR for working in laundry or dry cleaning compared to not working in this occupation was 2.50 (95% CI: 1.02,.... . middle of article......tal Health Perspectives 2006; NIOSH. National Occupational Exposure Survey (1981-1983). . Primary liver cancer and solvent exposure. Occupational and environmental health. 1984;54(2):147-153.5. Stemhagen A, Slade J, Altman R, Bill J. Occupational risk factors and liver cancer. Retrospective case-control of primary liver cancer in New Jersey. Journal of epidemiology April 1983;117(4):443-454.6. Lynge E, Carstensen B, Andersen O. Primary liver cancer and renal cell carcinoma. Laundry and Dry Cleaning in Denmark. Scandinavian Journal of Labour, Environment and Health. August 1995;21(4):293-295.7. dry cleaning: an update. Feb 2001;39(2):121-132.