Arsenic in public water supplies and cardiovascular mortality in Spain

Abstract Background High-chronic arsenic exposure in drinking water is associated with increased cardiovascular disease risk. At low-chronic levels, as those present in Spain, evidence is scarce. In this ecological study, we evaluated the association of municipal drinking water arsenic concentrations during the period 1998−2002 with cardiovascular mortality in the population of Spain. Methods Arsenic concentrations in drinking water were available for 1721 municipalities, covering 24.8 million people. Standardized mortality ratios (SMRs) for cardiovascular (361,750 deaths), coronary (113,000 deaths), and cerebrovascular (103,590 deaths) disease were analyzed for the period 1999−2003. Two-level hierarchical Poisson models were used to evaluate the association of municipal drinking water arsenic concentrations with mortality adjusting for social determinants, cardiovascular risk factors, diet, and water characteristics at municipal or provincial level in 651 municipalities (200,376 cardiovascular deaths) with complete covariate information. Results Mean municipal drinking water arsenic concentrations ranged from 10 μg/L. Compared to municipalities with arsenic concentrations 10 μg/L, respectively ( P -value for trend 0.032). The corresponding figures were 5.2% (0.8% to 9.8%) and 1.5% (−4.5% to 7.9%) for coronary heart disease mortality, and 0.3% (−4.1% to 4.9%) and 1.7% (−4.9% to 8.8%) for cerebrovascular disease mortality. Conclusions In this ecological study, elevated low-to-moderate arsenic concentrations in drinking water were associated with increased cardiovascular mortality at the municipal level. Prospective cohort studies with individual measures of arsenic exposure, standardized cardiovascular outcomes, and adequate adjustment for confounders are needed to confirm these ecological findings. Our study, however, reinforces the need to implement arsenic remediation treatments in water supply systems above the World Health Organization safety standard of 10 μg/L.