Dietary determinants of inorganic arsenic exposure in the Strong Heart Family Study

Background: Chronic exposure to inorganic arsenic (iAs) in the US occurs mainly through drinking water and diet. Although American Indian (AI) populations have elevated urinary arsenic concentrations compared to the general US population, dietary sources of arsenic exposure in AI populations are not well characterized. Methods: We evaluated food frequency questionnaires to determine the major dietary sources of urinary arsenic concentrations (measured as the sum of arsenite, arsenate, monomethylarsonate, and dimethylarsinate, Sigma As) for 1727 AI participants in the Strong Heart Family Study (SHFS). We compared geometric mean ratios (GMRs) of urinary Sigma As for an interquartile range (IQR) increase in reported food group consumption. Exploratory analyses were stratified by gender and study center. Results: In fully adjusted generalized estimating equation models, the percent increase (95% confidence interval) of urinary Sigma As per increase in reported food consumption corresponding to the lQR was 13% (5%, 21%) for organ meat, 8% (4%, 13%) for rice, 7% (2%, 13%) for processed meat, and 4% (1%, 7%) for non-alcoholic drinks. In analyses stratified by study center, the association with organ meat was only observed in North/South Dakota. Consumption of red meat [percent increase -7% (-11%, -3%)] and fries and chips [-6% (- 10%, - 2%)] was inversely associated with urinary Sigma As. Conclusions: Organ meat, processed meat, rice, and non-alcoholic drinks contribute to Sigma As exposure in the SHFS population. Organ meat is a unique source of Sigma As exposure for North and South Dakota participants and may reflect local food consumption. Further studies should comprehensively evaluate drinking water arsenic in SHFS communities and determine the relative contribution of diet and drinking water to total arsenic exposure.