Arsenic exposure in drinking water and the associated risk with coronary heart disease and type II diabetes mellitus

A case cohort study was conducted to investigate the association between cumulative arsenic exposure and both coronary heart disease and diabetes mellitus, controlling for known physiologic and behavioral risk factors. The study selected 626 subjects from the San Luis Valley Diabetes Study cohort. Subjects were recruited to participate in an interview to collect residential and employment location history and long-term water consumption patterns. A water sample was also collected and together with secondary data sources of arsenic concentrations, the results were incorporated into a complex spatial and temporal model reflecting the distribution of arsenic in drinking water using a Geographic Information System (GIS) to estimate lifetime arsenic exposure for each individual. Individual exposure estimates were compared to arsenic concentrations in a concurrently collected urine sample to determine the most accurate method for estimating biologic dose. A Cox proportional hazards model found an increased risk for CHD (Hazard Ratio [HR] =1.38; 95%CI=1.06, 1.78) and diabetes (HR=1.27; 95%CI=1.0, 1.59) with the time weighted arsenic exposure estimate while controlling for known behavioral, clinical, and demographic risk factors. Results showed a 38 percent increase in risk for CHD and a 20 percent increased risk for diabetes for every 15microg/I-year increase in the time weighted average inorganic arsenic concentrations in residential drinking water. Our study presents a positive association between chronic low-level inorganic arsenic exposure and CHD and diabetes. There are several directions for future research including: investigating the specific mechanism for arsenic toxicity especially within oxidative stress, potential genes and gene expression that interacts with arsenic exposure, and defining the clinically relevant exposure period for arsenic. Arsenic in drinking water is a common exposure in the United States and further research on these topics is crucial to elucidate the pathobiology of arsenic and CHD and diabetes.