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Speciation of Arsenic in Urine from the Health Effects of Arsenic Longitudinal Study (HEALS) Revealing New Arsenic Species and Individual Variability

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Summary

This 2026 cross-sectional biomonitoring study applied an improved anion-exchange HPLC-ICP-MS method to 1,873 urine samples from the HEALS (Health Effects of Arsenic Longitudinal Study) cohort in Araihazar, Bangladesh, where groundwater arsenic concentrations range from 0.1 to 864 ug/L. The study characterised the urinary profile of inorganic arsenic (iAs), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), and arsenobetaine (AsB), and identified uncharacterised arsenic species in a subset of participants (751/1,873; mean 1.8 ug/L). Participants with skin lesions (a clinical endpoint of chronic arsenic toxicity) had significantly higher concentrations of all measured urinary arsenic species compared to matched controls without skin lesions.

Key numbers

  • Mean total urinary arsenic: 114.3 ug/L (range 0.9-2,634 ug/L)
  • Mean urinary DMA: 79.2 ug/L (71.7% of sum of species)
  • Mean urinary MMA: 12.1 ug/L (11.0%)
  • Mean urinary iAs: 16.4 ug/L (14.8%)
  • Mean urinary AsB: 2.1 ug/L (1.9%)
  • Unidentified species: detected in 751/1,873 samples; mean 1.8 ug/L (range 0-42 ug/L)
  • R2 = 0.996 for regression of (iAs + MMA + DMA) sum vs. total As by ICP-MS
  • Skin lesion cases (n=76) had significantly higher DMA, iAs, MMA, and total arsenic (As) than matched controls (n=74; all p less than 0.05)

Methods

Anion-exchange HPLC-ICP-MS (Hamilton PRP-X100 column, 150 x 4.1 mm; mobile phase 10 mmol/L ammonium carbonate pH 10; isocratic elution approximately 10 min). LODs: 0.05 ug/L for iAs(III), iAs(V), MMA, DMA; 0.1 ug/L for AsB. Total urinary arsenic by ICP-MS after acid digestion. Urinary dilution correction by specific gravity.

Implications

This dataset represents the largest urinary arsenic speciation cohort from a high-exposure groundwater arsenic setting in peer-reviewed literature and is a primary reference for the urinary speciation profile of iAs, MMA, and DMA under chronic exposure. The methylation profile (DMA 71.7%, MMA 11.0%, iAs 14.8%) reflects efficient but incomplete methylation and is the benchmark for high-exposure populations. The association between urinary arsenic species and skin lesions confirms the biomarker validity of urinary speciation for chronic toxicity outcomes.

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