Background
Inorganic arsenic exposure in water and food is a global public health problem. Chronic exposure to high levels of arsenicis consistently associated with increased risk of cardiovascular disease, whereas prospective data on low to moderate chronic arsenic exposure (<100μg/L in drinking water) are lacking.
Objective
To evaluate the association between chronic low to moderate arsenic exposure and incident cardiovascular disease.
Design
Prospective cohort study.
Setting
The Strong Heart Study baseline visit in 1989-1991, with follow-up through 2008.
Patients
3,575 American Indian men and women aged 45-74 years living in Arizona, Oklahoma, and North and South Dakota.
Measurements
The sum of inorganic and methylated arsenic species in urine at baseline was used as a biomarker of chronic arsenic exposure. Participants were followed for incident fatal and non-fatal cardiovascular disease, including coronary heart disease and stroke.
Results
1,184 participants developed fatal and non-fatal cardiovascular disease and 439 participants developed fatal cardiovascular disease. Comparing the highest to lowest quartile arsenic concentrations (>15.7 vs. <5.8 μg/g creatinine), the hazard ratios (95% confidence interval) for cardiovascular disease, coronary heart disease, and stroke mortality after adjustment for socio-demographic factors, smoking, body mass index, and lipids were 1.65 (1.20, 2.27; p-trend<0.001), 1.71 (1.19, 2.44; p-trend<0.001) and 3.03 (1.08, 8.50; p-trend=0.061), respectively. The corresponding hazard ratios for incident cardiovascular disease, coronary heart disease, and stroke were 1.32 (1.09, 1.59; p-trend=0.002), 1.30 (1.04, 1.62; p-trend=0.006), and 1.47 (0.97, 2.21; p-trend=0.032), respectively. These associations varied by study region and were attenuated following further adjustment for diabetes, hypertension, and measures of kidney disease.
Limitations
Direct measurement of individual arsenic in drinking water was unavailable. Residual confounding and differences in potential confounders across study regions may exist.
Conclusions
Low to moderate chronic arsenic exposure, as measured in urine, was prospectively associated with cardiovascular disease incidence and mortality.