Genotoxicity of airborne PM 2.5 assessed by salmonella and comet assays in five cities of the Emilia-Romagna (Italy) mutagenicity monitoring network.

Airborne particulate matter (PM) has long been recognized as a potential health hazard and in 2013 was classified as carcinogenic to humans by the International Agency for Research on Cancer. In this study we evaluate and compare mutagenic and genotoxic potencies of PM2.5 collected in three seasons, from 2012 to 2015, in five Italian cities. Mutagenicity was evaluated through the Ames test on TA98 and TA100 strains and, for the measurement of PM clastogenicity, Comet assay was carried out on cultured human lung cells (A549). Organic matter, extracted from urban particulate matter, was also characterized for polycyclic aromatic hydrocarbons (PAHs) and their derivatives content. Samples collected in the colder seasons show the presence of both base pair substitution and frameshift mutagens, with enhanced mutagenic response in the absence of enzyme activation. The highest DNA damage detected with the Comet assay was induced by winter extracts, but different from Salmonella, the relative increase per cubic meter in comet tail for November samples was comparable to July ones. Comparing mutagenicity and genotoxicity with chemical concentrations we found that data from the Salmonella assay correlate with mass concentration and, to a lesser extent, with PAHs, but no association was found with their derivatives, whereas DNA damage correlate only with PAHs measured at one site. These findings demonstrate that to assess the mutagenicity and genotoxicity of complex mixtures it's necessary to use bioassays and that the chemical analysis of pollutants does not take into account the possible inhibitory or synergic effects of exposure. Environ. Mol. Mutagen. 58:719-729, 2017. © 2017 Wiley Periodicals, Inc.