In vitro bioaccessibility of metals in soils from a Superfund Site in Puerto Rico

摘要

For over 30 years the Municipality of Vega Baja-Puerto Rico (Figure 1) used a 19-acre parcel of land as a domestic, commercial and industrial landfill site where garbage was also cremated, resulting in approximately 8.5 X 10~5 m~3 of disposed waste,a practice which ended by 1979 (USEPA, 2002). During the 1970's people started constructing houses forming a community named "Brisas del Rosario" on this landfill-crematory site, with approximately 200 houses located on 11 acres. The United States Environmental Protection Agency (USEPA), and other federal and local health agencies became concerued with the health risk faced by this community located on a former industrial and domestic landfill. Past soil sampling conducted by the Puerto Rico Environmental Quality Board and the USEPA revealed significant levels of toxic chemicals such as Pb achieving concentrations as high as 26,000 mu g/g (ATSDR, 1998; USEPA, 2002). The health risk faced by this community, especially children, living on a hazardous waste site contaminated with high Pb soil concentrations, prompted the USEPA to declared it a Superfund Site (USEPA, 2002). According to the ATSDR (1998) and USEPA (2002), a major route of exposure to Pb for children living in "Brisas del Rosario" is contaminated soil. However, blood screening conducted only for Pb by the Puerto Rico Health Department (PRHD) in 1996 and 1998 in children aged 1-6 years old from "Brisas del Rosario" found blood Pb levels below 10 mu g/dL which did not reflect high soil Pb concentrations (ATSDR, 1998). Although the PRHD did not provide information on the discrepancy between blood and soil Pb concentrations, this could be partly explained by low bioaccessibility from soils due to high Pb-soil binding capacity impeding its dissociation into the stomach fluid and resulting in lesser amounts available for absorption.