Deposição atmosférica de metais pesados e avaliação de risco à saúde humana na cidade do Recife avaliados por musgos e exposição à poeira do asfalto

Abstract

Vehicular emissions are one of the main sources of heavy metals in urban areas due to the wear of automotive parts and products and the burning of fossil fuels that release waste into the atmosphere and can be deposited on the asphalt in the form of dust. The accumulation of metals in the dust can pose risks to human health due to direct contact with the population exposed mainly by the route of ingestion. In this sense, the study had as objectives (1) Biomonitoring the atmospheric deposition of barium, cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Vb) and zinc (Zn) by the use of mosses, (2) to evaluate the total and bioaccessible contents of these metals in samples of asphalt dust of the city of Recife and (3) to estimate the health risks of children and adults exposed to this material. The study area comprised 13 Recife urban streets with different traffic flows. Twenty - five samples composed of moss and thirty - nine samples composed of dust were collected by the routes. Moss samples were taken from trunks of tree species and dust samples were obtained by scanning 1 m² of asphalt. The total metals contents were extracted by total digestion of the moss and dust. Gastrointestinal bioaccessibility was based on the physiological basis extraction test. Total and bioaccessible contents were determined by ICP-OES. The total contents of the metals in the moss presented the following decreasing order (mg kg-1): Fe> Zn> Ba> Mn> Sr> Cu> Cr> Pb> V> Ni> Sb> Cd. (mg kg-1): Fe> Ba> Mn> Sr> Zn> Cu> Cr> Pb> V> Ni> Cd> Sb . The bioaccessible contents of all metals were higher in the gastric phase, being this enough to obtain the bioaccessibility of the metals in the dust. Carcinogenic and non-carcinogenic risks were reduced by the use of bioaccessible levels and were higher for children than for adults, but were classified as acceptable for all metals in all routes of exposure. The higher vehicular flow showed the highest atmospheric deposition of metals indicating a strong traffic relation with Recife air quality. The urban dusts of the city of Recife do not present significant risks to the health of the population. However, concentrations of metals should be monitored to prevent increased risk.