Oral and respiratory bioacessibility of potentially toxic elements in urban soils and sediments

Abstract

Human beings can be exposed to potentially toxic elements (PTE) daily, especially those living in large urban center with heavy traffic and industrial activities, such as steel, metallurgy, and mining. Risk assessment methods can predict or indicate the exposure levels to contamination of an area. Beside the PTE pseudo-total contents in the soil extracted by acid solutions, the reactive, (bioavailable, the bioaccessible contents and the inert fraction of these elements are also determined to assess the degree of soil contamination. In this project, urban soil samples will be collected in Piracicaba, where the levels of contamination are low. Other samples will be collected in Apiaí, state of Sao Paulo, in the Centro Integrado de Ensino Multidisciplinar (CIEM/ Companhia de Pesquisa de Recursos Minerais - Geological Survey of Brazil); and in Santo Amaro, state of Bahia, where urban soils will be collected in residential areas, especially near the old mining and refining area, where many researchers have detected high levels of Pb, Cd and As. In these cities, there is a very large environmental liability and it is generating risks to the health of local population. In-vitro methods have been used to evaluate PTE bioaccesibility in humans in many countries. We will test procedures based on ingestion and inhalation of urban soils and sediments of Piracicaba. The Unified BARGE Method (UBM) and the Gamble's Solution will be used to determine the bioaccessible content in the gastrointestinal (GI) tract and in the lung fluid, respectively. However, the bioaccessible fraction does not estimate the concentration that is absorbed and transported to the bloodstream. Therefore, Caco-2 cell line will be employed as a model to simulate human intestinal epithelium. Mineralogical and geochemical characteristics of soils and sediments will be correlated to lung fluid and gastric juice.