Arsenic in drinking and lung cancer mortality in Taiwan

The association between exposure to arsenic in drinking water and lung cancer has been observed in some epidemiology studies, but dose-response data are limited. To assess the dose-response relationship and identify hot spots, we analyzed the national death registry data of Taiwan from 1971 to 2000. We adopted data on 311 townships gathered by a nationwide survey of drinking water and divided arsenic levels into three groups: below 0.05 mg/L, 0.05-0.35 mg/L, and above 0.35 mg/L. Using the direct standardization method to adjust for the effects of age, we calculated the standardized mortality rates of lung cancer in both genders and evaluated their associations with arsenic levels. We also used the geographical information system to identify the hot spots. During the 30-year study period, we identified 64,954 male and 27,039 female lung cancer deaths in the study townships. We found significant increases in lung cancer mortality associated with arsenic levels above 0.35 mg/L in both genders, but the increases associated with levels between 0.05 and 0.35 mg/L were statistically significant in men only. Using both 0.05 and 0.35 mg/L as the cut-offs, we found most of the hot spots were in the southwestern coast and northeastern areas, but the southwestern coast area had some hot spots where the percentages of high risk population were higher than any hot spots in the northeastern area.