Arsenic in Drinking Water and Adult Mortality A Population-based Cohort Study in Rural Bangladesh

Background: Arsenic is a potent human carcinogen and toxicant. Elevated concentration of arsenic in drinking water is a major public-health problem worldwide. We evaluated risks of adult mortality (due to cancer and cardiovascular and infectious diseases) in relation to arsenic exposure through drinking water. Methods: A cohort analysis was applied to survival data prospectively collected during 1991-2000 in a health and demographic surveillance system in Matlab, Bangladesh, where tubewells were installed beginning in the early 1970s. A total of 115,903 persons aged 15 or more years on I January 1991 were available for analysis. In this period, 9015 people died and 22,488 were lost to follow-up. Arsenic exposure data were derived from a survey in 2002-2003 of past and current water use and arsenic concentrations in all tubewells. We estimated risk of excess mortality in relation to arsenic exposure, using proportional hazards models. Results: Even at low levels (10-49 mu g/L) of arsenic in drinking water, we observed increased risk of death due to all nonaccidental causes (hazard ratio = 1.16 [95% confidence interval = 1.06-1.26]). Increased risks at exposure of 50-149 mu g/L were observed for death due to cancers (1.44 [1.06-1.95]), cardiovascular disease (1.16 [0.96-1.40]), and infectious diseases (1.30 [1.13-1.49]). We observed clear dose-response relationships for each of these causes. Conclusions: Arsenic exposure through drinking water has generated excess adult mortality after 20-30 years of exposure.