Exposure and risk assessment to arsenic species in Spanish children using biomonitoring.

We present a new approach to arsenic (As) risk assessment using biomonitoring. In this pilot study we determined the levels of total and speciated urinary arsenicin 109 Spanish school children aged between 6 and 11 years, and interpreted these concentrations in a risk assessment context. The geometric mean (GM) for total As (TAs) was 33.82 μ/L. The order of occurrence and average concentrations of the different species was arsenobetaine (AsB) (100%, 15 μg/L), dimethylarsinic (DMA) (97%, 8.32 μg/L), monomethylarsonic (MMA) (26%, 0.27 μg/L) and inorganic As (iAs) (4%, 0.14 μg/L). 18% of children presented exposures to inorganic arsenic (7.52 μg/g creatinine) higher than guidance value for non-cancer risk (8.3 μg/g creatinine). For cancer risk the exposure to inorganic arsenic was much higher than the guidance value. Urinary DMA was positively associated with urinary AsB, suggesting exposure directly to this specie or metabolism of organic arsenicals to this specie, mainly through seafood consumption. Consequently, the exposure to inorganic As needs to be carefully interpreted because it may be overestimated. Our study supports the hypothesis that urinary iAs + MMA is the most reliable biomarker of exposure to inorganic As.