Airborne particulate matter in an iron mining city: Characterization, cell uptake and cytotoxicity effects of nanoparticles from PM2.5, PM10 and PM20 on human lung cells

Abstract

Airborne particulate matter (PM) is dispersed into the atmosphere and can internalize in the lungs during the respiratory process by passive exposure. Itabira city (Minas Gerais, Brazil) is a mining city with relevant PM emissions derived from iron exploitation, transport, and processing. In the present study, the PM2.5, PM10, and PM20 characterization from iron ore and its internalization and cytotoxicity effects were evaluated in the MRC-5 human lung cell line. PMs were characterized using scanning electron microscopy with EDS and X-ray analysis and, then, dispersed in water and analyzed by Dynamic Light Scattering and Nanosight techniques. Flow cytometry was applied to evaluate PM cellular uptake on MRC-5 cells and death induction. The results demonstrate that the PM10 mass collected were higher than those reported by the local governmental agencies and the PMs are mainly constituted by hematite and quartz. EDS analysis showed the presence of Fe, Si, Mg, Al, Zi, Ca, and emerging metallic contaminants, such as Ba and Ti, in environmental samples. Analyzed PM samples dissociate into nanoparticles (< 200 nm) in aqueous medium, demonstrating that the PM comprises aggregated nanoparticles that can be internalized in cells, leading to a decrease in cell viability. Thus, reducing PM exposure may be considered as a potential tool for reducing metal contaminants in the air and respiratory diseases. In view of the health and environmental problems caused by airborne PM pollution, this study brings new discussions aiming to improve safety standards and future investigations in this field worldwide.