Trichloroethylene and cancer: a carcinogen on trial.

The organic solvent trichloroethylene has been used in dry cleaning, as an industrial degreasing agent and as a solvent for oils and resins; large numbers of workers have been exposed to trichloroethylene, mainly by inhalation. Trichloroethylene has been categorised as a Group 2A carcinogen (probably carcinogenic to humans) by the International Agency for Research on Cancer (World Health Organization) and a Category 2 carcinogen (to be regarded as carcinogenic to humans) by the Australian National Industrial Chemicals Notification and Assessment Scheme. The Administrative Appeals Tribunal was asked to determine the validity of classifying trichloroethylene as a Category 2 rather than a Category 3 (data inadequate for making a satisfactory assessment) carcinogen. In the AAT's determination, relevant epidemiological evidence was not taken into account because such evidence concerned tumour sites apart from the kidney (the site of tumour induction by trichloroethylene in rats). This mode of evaluation is fundamentally different from that used by the International Agency for Research on Cancer. The precedent set by the consideration of carcinogenicity data in this case could have significant implications for classification of other putative carcinogens