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Abstract

Argos M, Kalra T, Rathouz PJ et al. Arsenic exposure from drinking water, and all-cause and chronic-disease mortalities in Bangladesh (HEALS): a prospective cohort study. Lancet 2010; 376:252-8 Background: Arsenic exposure from contaminated groundwater is a worldwide public health concern. An estimated 35-77 million people in Bangladesh have been chronically exposed to inorganic arsenic after installation of millions of deep tube wells intended to provide a pathogen-free water supply. Prospective investigation of an association between arsenic exposure and mortality with individual level data has not been performed. Research question: Is chronic arsenic exposure, as measured by repeated individual total urinary arsenic levels, associated with increased all-cause and chronic-disease mortality? Methods: A prospective cohort study was performed on adult (age 18-75 years) residents of Araihazar, Bangladesh. Study participants were recruited over a 2-year period and follow-up was performed biennially. Trained physicians blinded to arsenic concentrations in local well water utilized a verbal autopsy questionnaire and collected clinical samples. Well water was analyzed for arsenic concentration. A Cox proportional hazards model was used to analyze hazard ratios for mortality. Results: Eleven thousand seven hundred forty-six participants were recruited over the study period. Mean follow-up time was 6.5 years. Four hundred seven deaths were detected from the beginning of recruitment to the end of the follow-up period. Multivariateadjusted hazard ratios showed an increased risk of mortality at all concentrations of arsenic in well water. A one-quartile increase in arsenic concentration in well water was associated with 15% increase in all-cause mortality (95% CI 1.05-1.26). Recent change in exposure did not have a significant effect on mortality. Investigators estimated that over 20% of deaths could be attributed to elevated arsenic concentrations in drinking water. Conclusion: Chronic exposure to arsenic in well water was associated with increased all-cause and chronic-disease mortality. Critique: The method employed for measuring the concentration of urinary arsenic levels did not allow for speciation; therefore, estimation of nontoxic organic arsenic compounds such as arsenobetaine was unavailable. Arsenic dose was calculated in part by employing selfreported estimates of water intake. Furthermore, assigning the cause of death relied on accurate description of chronic diseases and symptoms in the deceased by relatives or neighbors. A longer follow-up period might better show the effects of remediation efforts, as subjects with decreasing urinary arsenic levels did not show a similar decline in mortality risk. Implication for toxicologists: This study highlights the consequences of an ongoing public health crisis. Strategies