Association between drinking water arsenic and urinary inorganic arsenic in the US: NHANES 2003-2014

Abstract

BACKGROUND AND AIM: Important inequalities exist in arsenic (As) in drinking water across US populations. A critical research gap is how water As corresponds to internal dose, measured by urinary biomarkers. We evaluated the association between assigned private well and regulated community water system (CWS) As and urinary As concentrations in the National Health and Nutrition Examination Survey (NHANES). METHODS: We assigned 13,163 NHANES 2003-2014 participants county-level population- weighted CWS concentrations (µg/L) and private well estimates (probability >10 µg/L) using published nationwide estimates from US Environmental Protection Agency and US Geological Survey datasets, respectively. The internal dose of inorganic As related to drinking water was estimated by recalibrating urine dimethylarsinate (DMA) concentrations to adjust for arsenobetaine, seafood, smoking status, and past 24-hour intake of rice and other dietary sources. We evaluated geometric mean ratios (GMRs) of DMA across tertiles of water As, the lowest tertile as reference, for all participants and stratified by census region and quartile of geologic risk of elevated water As. RESULTS: Among CWS users, participants in the highest tertile of CWS As had significantly higher DMA overall (GMR= 1.17, 95% CI 1.09, 1.26) and in the South (GMR =1.23, 95% CI 1.09, 1.38), compared to participants in the lowest tertile. Among private well users, participants in the highest tertile of private well As had significantly higher DMA overall (GMR = 1.23, 95% CI 1.01, 1.50) and in the West (GMR = 1.34, 95% CI 1.18, 1.53). CONCLUSIONS: Arsenic in private wells and CWSs contributes to As exposure, measured in urine, in general US populations. Water As and urine DMA were more strongly associated among private-well users compared to CWS users nationwide, with differences by region. Positive associations were also observed among CWS users in the highest two quartiles of geologic risk. KEYWORDS: arsenic, exposure, water quality