Cytotoxic effects induced in vitro by organic extracts from urban air particulate matter in human leukocytes

Urban areas represent major pollution sources as a result of anthropogenic activities located in these districts. Among the legislated air pollutants, polycyclic aromatic hydrocarbons (PAHs), which are mostly adsorbed on the surface of dust particles, are known for their adverse health effects. The present study has been carried out to examine the cytotoxic effects induced in vitro on human peripheral monocytes (PBMCs) by extractable organic matter (EOM) from PM10 (characterized for its PAH content) collected at four sites in the urban center of Messina, Italy. Chromatographic analyses showed the presence of PAHs in all EOM. Only EOM from one site induced a marked cell death probably resulting from the highest PAH content in this sample. Conversely, apoptosis activation was evident after PBMC exposure to all the EOM tested. These apoptotic effects do not appear related only to the total PAH content, but are probably influenced by chemical composition. In conclusion, our findings confirm that the cytotoxic potential of organic matter associated to ambient respirable air particles depends predominantly on the quantity and quality of the chemicals contained in it. In particular, the present data strongly evidence that the only evaluation of air concentration of particulate matter and benzo[a] pyrene, as well as the generally used risk models based on additivity, are not sufficient to evaluate air quality and PAH effect on human health because they do not take into account the possible inhibitory or synergic or antagonistic effect of combined exposure and the interference of other organic compounds present in respirable matter.