This project studies risks, mechanisms and susceptibility in the aetiology of bladder, skin and kidney cancers in relation to arsenic in drinking water. For 1200 cases and 600 controls, estimates of the cumulative dose will be constructed and cancer risks will be estimated in relation to arsenic intake, adjusting for potential confounding by diet, tobacco and occupation. The impact on risk of individual differences in arsenic metabolism, DNA repair and diet will be assessed. For subgroups of the population more detailed analyses of inter-individual differences in speciation, the effect of other nutrients and minerals, and specific polymorphisms will inform models of metabolism. Risk management will be explored for those with the highest continuing exposure. The project will improve quantitative risk assessments, understanding of mechanisms of arsenic toxicity and communication among European researchers in this field.