Lead in Urban Soils: Relation between the Hazard Exposure from Bioaccessible Fraction and Soil Fractionation

Abstract

ABSTRACT Lead is a toxic metal that can cause harmful effects on the environment and human health. In urban areas, airborne particulates can be a source of lead that can be deposited in urban soils. Therefore, this study aims to investigate the Pb bioaccessibility in urban soils and also correlate the solid-phase distribution sequential extraction steps with the gastric phase oral in bioaccessibility of Pb, since it can be an indicator of contamination potential human health risk. The study was conducted in the city of Ribeirão Preto, Brazil, a city with 700,000 habitants which has an intense vehicular traffic. The sequential extraction revealed that the highest amount of lead is bonded in Fe – Mn oxides in soil and at the residual phase, indicating the low leachability of Pb. The bioaccessibility assay showed a high release of Pb in the gastric phase and hazard quotient values of the samples were high for children, indicating higher potential harmful effects. This study also evidenced the relation between the release of Pb by different soil fractions and the bioaccessibility, since acid-extractable fractions can increase the Pb bioaccessibility in gastric phase.