Long-Term Exposure to Arsenic in Community Water Supplies and Risk of Cardiovascular Disease among Women in the California Teachers Study

Introduction Inorganic arsenic in drinking water (wAs) remains an environmental exposure of concern, potentially linked to several prevalent chronic diseases in the US. (1,2) According to the American Heart Association [...]
BACKGROUND: Inorganic arsenic in drinking water (wAs) is linked to atherosclerosis and cardiovascular disease. However, risk is uncertain at lower levels present in US community water supplies (CWS), currently regulated at the federal maximum contaminant level of 10 [micro]g/L. OBJECTIVES: We evaluated the relationship between long-term wAs exposure from CWS and cardiovascular disease in the California Teachers Study cohort. METHODS: Using statewide health care administrative records from enrollment through follow-up (1995-2018), we identified fatal and nonfatal cases of ischemic heart disease (IHD) and cardiovascular disease (CVD). Participants' residential addresses were linked to a network of CWS boundaries and annual wAs concentrations (1990-2020). Most participants resided in areas served by a CWS (92%). Exposure was calculated as a time-varying, 10-year moving average up to a participant's event, death, or end of follow-up. Using Cox models, we estimated hazard ratios (HRs) and 95% confidence intervals (95% CIs) for the risk of IHD or CVD. We evaluated wAs exposure categorized by concentration thresholds relevant to regulation standards ( RESULTS: Our analysis included 98,250 participants, 6,119 IHD cases, and 9,936 CVD cases. The HRs for IHD at concentration thresholds (reference, 55 years of age at enrollment ([p.sub.interaction] = 0:006 and 0.012 for IHD and CVD, respectively). DISCUSSION: Long-term wAs exposure from CWS, at and below the regulatory limit, may increase cardiovascular disease risk, particularly IHD. https://doi.org/10.1289/EHP14410