DNA damage in A549 cells exposed to different extracts of PM2.5 from industrial, urban and highway sites.

The aim of this research is to investigate the role played by the chemical fraction of PM2.5 in the DNA damage induction in human lung cells (A549): in particular the effects of samples collected in urban, industrial and highway sites were compared. Organic and water-soluble extracts of PM2.5 were analysed to quantify PAHs (by GC-MS technique) and metals (by ICP-MS technique) and tested on A549 cells to evaluate, by the Comet assay (without and with Fpg enzyme), genotoxic and oxidative damage. The chemical analysis showed a variability of PAH composition in PM organic extracts of the three different sites and pointed out the presence of 14 metals (being Fe, Cu, Zn, Sb and Ba the most abundant) in all the PM water extracts. Regarding the biological effect, all the PM2.5 organic extracts caused a significant dosedependent increase of the A549 DNA damage. The genotoxic effect was related to the PM2.5 PAH content and the highest effect was observed for the highway site sample. The DNA oxidative damages were observed for the PM2.5 water extracts of the samples collected in industrial and highway sites. The extent of the oxidative damage seems to be related to the kind and concentration of the metals present. The results of this study emphasize the importance of PM chemical composition on the biological effects and highlight the need, when evaluating the effects on health and exposure management, to always consider, beside size and concentration of PM, also their qualitative composition.