Abstract
Urinary concentrations of inorganic arsenic (iAs) metabolites have been used as biomarker of exposure in the previous studies. However, whether or not iAs and its metabolite concentration in spot urine represents long-term iAs exposure level of the individual has not been extensively studied. The aim of this study was to quantitatively compare inter- and intra-individual variability of urinary iAs metabolites in Japanese subjects for evaluating whether single spot urine is suitable medium for the assessment of long-term iAs exposure. We collected five first morning urine samples from each of 14 healthy female subjects for 4 - 5 months at 2 - 3 weeks interval. Urinary iAs and its metabolites concentrations were determined by liquid chromatography-ICP mass spectrometry with a hydride generation system. The median concentration of iAs + methylarsonic acid in 70 urine samples was 1.90 µg As/g-cre (range: <0.47 - 58.3). The intraclass correlation coefficient of urinary concentration of iAs + methylarsonic acid of the 14 subjects were 0.15, indicating poor reproducibility. It was shown that the concentration of iAs metabolites in single spot urine is not a suitable biomarker of long-term exposure levels of iAs in Japanese at individual level; it was estimated that four spot urine samples were required from a subject for that purpose.
