Low-level arsenic in drinking water and risk of incident myocardial infarction: A cohort study

Background: Epidemiological studies have shown that intake of drinking water with high levels of arsenic ( > 100 mu g/L) is associated with risk for cardiovascular diseases, but studies on lower levels of arsenic show inconsistent results. Objective: The aim of this study was to investigate the relationship between exposure to low level arsenic in drinking water and risk of myocardial infarction in Denmark. Methods: From the Danish Diet, Cancer and Health cohort of 57,053 people aged 50-64 years at enrolment in 1993-1997, we identified 2707 cases of incident myocardial infarction from enrolment to end of follow-up in February 2012. Cohort participants were enrolled in the Copenhagen and Aarhus areas. We geocoded residential addresses of the cohort members and used a geographic information system to link addresses with water supply areas. Arsenic in tap water at each cohort members address from 1973 to 2012 was estimated for all cohort members. Poisson regression was used to estimate incidence rate ratios (IRRs) for myocardial infarction after adjustment for lifestyle factors and educational level. Results: Arsenic levels in drinking water at baseline addresses ranged from 0.03 to 25.34 mu g/L, with the highest concentrations in the Aarhus area. We found no overall association between 20-years average concentration of arsenic and risk of myocardial infarction. However, in the Aarhus area, fourth arsenic quartile (2.21-25.34 mu g/ L) was associated with an IRR of 1.48 (95% confidence interval (CI): 1.19-1.83) when compared with first quartile (0.05-1.83 mu g/L). An IRR of 1.26 (95% CI: 0.89-1.79) was found for ever (versus never) having lived at an address with 10 mu g/L or more arsenic in the drinking water. Conclusions: This study provides some support for an association between low levels of arsenic in drinking water and the risk of myocardial infarction.