Iron and Zinc Supplementation Does Not Impact Urinary Arsenic Excretion in Mexican School Children

Objective To examine the role of iron and zinc in arsenic excretion and metabolism in children. Study design An analysis of urinary arsenic (UAs) concentrations from a double-blind randomized trial originally testing the efficacy of iron and zinc for lowering blood lead levels in children. A 2 × 2 factorial design was used, with children randomized individually, stratified by sex and classroom, to receive 30 mg ferrous fumarate (n = 148), 30 mg zinc oxide (n = 144), iron and zinc together (n = 148), or placebo (n = 151). Of the 602 children enrolled, 527 completed the 6-month treatment, and 485 had both baseline and final UAs values. The baseline total UAs concentration ranged from 3.2 to 215.9 µg/L. Results At baseline, children in the highest tertile of serum ferritin concentration had higher excretion of dimethylarsinic acid (DMA; 1.93 ± 0.86%; P <.05), but lower excretion of monomethylarsonic acid (-0.91 ± 0.39%; P <.05), compared with children in the lowest tertile. In an intention-to-treat analysis, iron had no effect on arsenic methylation or UAs excretion, but children receiving zinc had lower %DMA in urine (-1.7 ± 0.8; P <.05). Conclusions Iron and zinc status are not related to arsenic metabolism in children, and supplementation with these minerals has limited application in lowering arsenic concentrations. Trial registration ClinicalTrials.gov: NCT02346188.