Biomonitoring of 20 elements in urine of children. Levels and predictors of exposure

The levels of 20 elements in the urine of one hundred twenty children (Ages 6–11) from an agricultural and an urban area of Valencia Region, Spain, were assessed. The seven essential elements analysed (Co, Cu, Mn, Mo, Se, V, Zn) presented average concentrations (geometric mean) ranging from 0.22 µg L−1 to 63 µg L−1 (except Zn with 525 µg L−1). Eight out of the 13 toxic elements determined (As, Ba, Cd, Cs, Ni, Pb, Tl, Hg) had frequencies of detection of 100%, with geometric mean concentrations from 0.17 µg L−1 (Cd) to 33.6 µg L−1 (As). About 18% of children revealed urinary levels of total As higher than the normal range of 100 µg L−1 accepted by the ATSDR. The urine analysis was combined with a survey to evaluate variations between subgroups and potential predictors of metal exposure in children population. For socio-demographic variables, age was the main exposure determinant for the majority of selected elements (p < 0.05–0.001), with higher concentrations in younger children (6–8 years). Significant differences were also obtained between the rural and urban area studied for As, Co, Cs, Se, U and Hg, with higher levels in children living in the urban area. In relation to diet, statistically significant higher levels of Hg (p < 0.01, median = 1 µg g−1 creatinine) and Se (p < 0.05, median = 60.3 µg g−1 creatinine) were obtained for children with elevated fish consumption, and lower levels of Cd, Ni, Se and V were found (p < 0.05–0.01) in children with high consumption of dairy products.