Objective: Lung cancers have been observed among patients of arsenic intoxication since the 1950s, but data on the dose-response relationship were limited. In order to obtain such data, a study was conducted in ten townships in Taiwan.
Methods: Measurements of arsenic levels in drinking water were available for 138 villages from a census survey conducted by the government. Certificates of deaths that occurred in the villages between January 1, 1971 and December 31, 1990 were reviewed, and 673 male and 405 female mortality cases of lung cancer were identified. Multi-variate regression models were applied to assess associations between arsenic levels in drinking water and mortality of lung cancer using village as the unit.
Results: After adjusting for age, arsenic levels above 0.64 mg/l were associated with a significant increase in the mortality of lung cancer in both genders, but no significant effect was observed at lower levels. Post-hoc analyses confirmed such a dose-response relationship.
Conclusions: The results indicate a prominent carcinogenic effect of high arsenic levels in drinking water on the lung and suggest the new 'maximum contaminant level' of 10 micro g/l published by the US Environmental Protection Agency provides sufficient protection against lung cancer. Nonetheless, further studies with exposure data on individuals are warranted to confirm these findings.