Prepregnancy exposure to dietary arsenic and congenital heart defects.

INTRODUCTION: Arsenic crosses the placenta and accumulates in fetal tissues. In the United States, diet is the predominant route of arsenic exposure, but epidemiologic data are sparse regarding this exposure and development of birth defects. Using data from a large case-control study, we explored associations between maternal dietary arsenic exposure and congenital heart defects (CHDs), the most prevalent birth defects. METHODS: We used maternal self-reported dietary assessments and arsenic concentration estimates in food items to estimate average daily exposure to dietary arsenic during the year before pregnancy for mothers of 10,446 unaffected control children and 6,483 case children diagnosed with CHDs. Using tertiles of dietary exposure to total arsenic (all species) and inorganic arsenic, we applied logistic regression analysis to estimate associations for middle and high tertiles, compared with the low tertile. RESULTS: Positive associations (odds ratio [OR] ≥ 1.2) for total arsenic were observed in both tertiles for perimembranous ventricular septal defect (VSD) and high tertile only for double outlet right ventricle-transposition of the great arteries (DORV-TGA), partial anomalous pulmonary venous return (PAPVR), and tricuspid atresia. Positive associations were also observed in both tertiles (tricuspid atresia) and high tertile only (DORV-TGA, conoventricular VSD, PAPVR, and pulmonary atresia) for inorganic arsenic. Most remaining associations were near or below unity. DISCUSSION: Exploration of maternal dietary exposure to total and inorganic arsenic and CHDs produced few positive associations but was limited by available food item concentrations. Future research requires expanded collection of dietary data, improved estimates of concentrations, and consideration of nondietary sources of arsenic exposure.