Determinants of lead exposure in children on the outskirts of Salvador, Brazil

Lead (Pb) is a toxic heavy metal that is widely distributed throughout the environment. Pb is an important neurotoxic metal and children are more susceptible to its effect due to their higher absorption rate and greater susceptibility of the developing nervous system. In this work, we evaluated the lead exposure levels in children living near a metallurgical plant and identified risk factors associated with its internal dose. All children, aged 1-10 years and 11 months, living near a metallurgical plant in the great Salvador area, Brazil were evaluated in this cross-sectional study and compared with children from a non exposed area. Occipital hair and blood were used to assess exposure. Air lead levels in the respirable fraction (PM2.5) were also measured in both areas. Blood lead levels (BLL), hair lead levels (PbH) and air lead were determined by graphite furnace atomic absorption spectrometry. Spearman correlations analysis was used to evaluate correlations between BLL, PbH and descriptors. Significant risk factors were modeled using multivariate linear regression analysis. Air lead levels were approximately ten-folds lower than EPA reference concentration (0.15 mu g/m(3)). Median BLL and PbH were1.65 +/- 1.45 mu g/dL and 1.26 +/- 3.70 mu g/g, respectively, in exposed children. In the referents, medians were BLL 1.20 +/- 1.20 mu g/dL; PbH 2.09 +/- 2.06 mu g/g. No significant difference was observed in biomarkers levels between boys and girls. It was observed a positive weak correlation (Spearman rho = 0.197, p = 0.033) between BLL and PbH. Our data show that children's lead body burden measured as BLL or PbH are low when compared with the recommended reference values. Despite that, we were able to identify four risk factors associated with increased biological lead levels: age, living near industrial site, environmental tobacco smoking and, above all, domestic waste burning. In order to prevent such avoidable exposure, environmental education and proper waste management should be implemented, especially in developing countries.