Carcinogenicity of perfluorooctanoic acid, tetrafluoroethylene, dichloromethane, 1,2-dichloropropane, and 1,3-propane sultone

DCM was classified as probably carcinogenic to humans (Group 2A) on the basis of limited evidence that it causes biliary-tract cancer and non-Hodgkin lymphoma in humans and sufficient evidence of carcinogenicity in experimental animals (malignant lung and hepatocellular tumours in male and female mice).2,3,6-9 In making its overall assessment, the working group also took into account the strong evidence that DCM metabolism via glutathione-S-transferase T1 (GSTT1) leads to the formation of reactive metabolites, that GSTT1 activity is strongly associated with genotoxicity of DCM in vitro and in vivo, and that GSTT1-mediated metabolism of DCM does occur in humans. DNA reactivity was evident in various genotoxicity assays, including in animals and in human cells in vitro. Because 1,3-PS does not require metabolic activation and reacts directly with DNA and other macromolecules, the working group concluded that this mechanism probably operates both in animals and humans.