"Renal cell cancer is not generally considered an occupationally associated tumor. . . . Considerable interest has recently been focused on the solvent trichloroethylene (TCE), largely as a result of bioassay findings in animals and of three studies conducted in the same area of Germany, which were initiated in response to clusters of renal cell cancer cases and which reported strikingly elevated relative risks for renal cell cancer associated with TCE exposure. These findings contrast starkly with results from other investigations, and several serious methodological shortcomings of these studies have been noted." [Schottenfeld, p. 1092-3] "Extensive epidemiologic cohort studies of TCE-exposed workers do not indicate significant increases in cancer incidence, but case-control studies suggest that prolonged exposure to high concentrations of TCE (hundreds to thousands of ppm) can increase the incidence of renal cancer." [ACGIH] "As in the rat studies, kidney toxicity is believed to be a prerequisite for the development of renal cancer in humans following exposure to trichloroethylene." [
PMID 15031388] The high levels of exposure have been documented for the various types of degreasing processes by Bakke, Stewart, and Waters [
PMID 17454505] and also by Fevotte et al. [
PMID 16840434] TCE was classified as carcinogenic to humans (Group 1) by the Working Group in October 2012. [
PMID 23323277] In the 2013 Hansen et al. paper on the Nordic Cohort Studies, the authors mention the IARC decision in 2012 to link TCE to occupational kidney cancer. In explaining why their study found no association between TCE and kidney cancer, the authors write, "Duration of exposure, as well as exposure levels of TCE, have in general been relatively low in Finland, Sweden, and Denmark, and if TCE is a risk factor for kidney cancer only at extremely high levels of TCE-exposure, this may explain in part our overall null finding for this cancer." [
PMID 23723420]