Incidence of coronary heart disease in relation to lifetime exposure to inorganic arsenic in drinking water in Colorado

Consumption of drinking water with high levels of inorganic arsenic (over 1000μg/L) has been associated with coronary heart disease (CHD), but previous studies have been inconclusive about risks at lower levels (10μg/L -100μg/L). We present a cohort study based on individual estimates of lifetime arsenic exposure to further examine the relationship between chronic low-level arsenic exposure and risk of CHD. This study in San Luis Valley, Colorado included a cohort of 555 participants with 96 CHD events diagnosed between 1984 and 1998. Individual lifetime arsenic exposure estimates were determined using a methodology that incorporates the use of a structured interview, mobility history, geospatial modeling of arsenic concentrations in drinking water, and urine arsenic concentrations. A Cox proportional hazards model with known CHD risk factors as time-dependent covariates was used to assess the association between lifetime exposure to inorganic arsenic in drinking water and incident CHD, adjusting for known CHD risk factors of age, gender, first degree family history of CHD, and serum low density lipoprotein levels. There was a positive association between inorganic arsenic exposure and coronary heart disease risk (multivariate-adjusted HR per 15 ug/L=1.38, 95%=1.06, 1.78). We also found a dose response relationship between inorganic arsenic exposure (<20 ug/L, 20-30 ug/L, 30-45 ug/L, and > 45 ug/L) and CHD risk (adjusted HR= 1.00, 1.24, 2.14, 3.12 respectively, trend p<.001). Exposure to inorganic arsenic in drinking water, even at levels below 100 μg/L, may increase risk for CHD.