Water Dilutes and Alcohol Concentrates Urinary Arsenic Species When Food is the Dominant Source of Exposure

Exposure to certain arsenic (As) species has been associated with increased cancer risk and a wide range of other health concerns, even at low levels. Here we used urine as a biomarker of As internal dose in a well-characterized cohort to relate diet, demographics and geography to exposure. As speciation in spot urine samples was determined for 89 participants aged >= 50 years from the Northern Ireland Cohort for the Longitudinal Study of Ageing (NICOLA), stratified to cover the country. Principal component analysis showed that all As species clustered together, suggesting that arsenobetaine, inorganic As (iAs) and the methylated species monomethylarsonic acid and dimethylarsinic acid forms have a common source. Seafood and alcohol consumption were positively correlated with As species, while dairy products (i.e. milk) and tap water were negatively correlated. Multiple regression analysis showed that diet explained approximately 30% of the variability in urinary iAs concentrations. Geography was not found to be a predictor of As exposure. Dairy consumption was negatively correlated and the best predictor of iAs in urine, explaining 15.9% of the variability. The majority of the variation in As biomarkers was not explained, suggesting the contribution of other sources and other non-predicted variables on As metabolism and elimination.