Characterization of urban aerosol: Seasonal variation of genotoxicity of the water-soluble portion of PM2.5 and PM1.

Urban particulate matter (PM) is a complex mixture of several classes of chemicals: elemental carbon, ammonium, sulfates, nitrates, organic compounds and metals. For a long time, numerous studies had shown that PM causes health problems and, in 2013, it has been classified by the International Agency for Research on Cancer as carcinogenic to humans (group 1). Furthermore, it's known that the fine fraction of PM is the most genotoxic, and that smaller particles are retained by the lower respiratory system, making fine particles a public health concern. In this study we characterize the water-soluble portion of urban aerosol from Bologna, a county town of Emilia-Romagna in the north of Italy, by collecting the finest fractions of airborne particles, PM2.5 and PM1, in three different seasons (winter, summer and autumn) over a three-year period. The genotoxicity of the water-soluble extracts was evaluated, both by a standard and a enzyme-modified Comet assay and also by the Micronucleus test, with lung adenocarcinoma epithelial cells (A549). In the same extracts, water-soluble metals (V, Ni, Cu, Cr, Fe) were detected and associations between the physicochemical parameters of PM and genotoxicity were evaluated. DNA strand breaks were found in summer and winter samples in the Comet experiments, whereas oxidative damage was induced by autumn extracts; winter samples induced chromosome breakage or loss in A549 cells. Iron and copper were the most abundant transition metals in both fractions and both were associated with micronuclei induction, whereas chromium is linked with oxidative damage. This study also shows that the water-soluble fraction of PM contributes to global genotoxicity and that transition metals play a role, therefore both organic and water-soluble fractions should be considered in an air-quality monitoring program.

Genotoxicity of airborne PM2.5 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.

Characterization of urban aerosol: seasonal variation of mutagenicity and genotoxicity of PM2.5, PM1 and semi-volatile organic compounds.

Urban particulate matter (PM) is an environmental public health concern as it has been classified by the IARC as carcinogenic to humans (group 1) and it's well known that pollutants are more associated with the finest fractions of PM. In this study we characterize urban aerosol in Bologna, county town of Emilia-Romagna in the north of Italy, collecting PM2.5, PM1 and semi-volatile organic compounds using polyurethane foam. Samples were collected in three different seasons (winter, summer and autumn) and were extracted with acetone. On these three fractions we assessed mutagenicity using Salmonella reverse mutation test and genotoxicity by alkaline comet assay and micronucleus assay in human lung cancer cell line, A549. Organic extracts were also characterized for alkanes, polycyclic aromatic hydrocarbons (PAHs), nitrated and oxygenated PAHs. We also evaluated associations between the physicochemical parameters of samples and their genotoxicity. The particulate samples, collected in autumn and winter, indicated the presence of both base pair substitution and frameshift mutagens using TA98 and TA100 strains of Salmonella typhimurium and the mutagenicity was more associated with the finest fraction. Enhanced mutagenic response was observed in the absence of enzyme activation. Only a third of comet and a half of micronucleus assays gave positive results that, unlike Salmonella's ones, are not season-related. These results were compared with environmental chemicals concentrations and we found that Salmonella's data correlated with PAHs detected on PM filters and with mass concentrations, whereas the DNA damage correlate only with PAHs extracted from polyurethane foams. The use of different assays was sensitive to detect and identify different classes of airborne mutagenic/genotoxic compounds present in aerosol, showing that monitoring air quality using this methodology is relevant.

The Salmonella mutagenicity of urban airborne particulate matter (PM2.5) from eight sites of the Emilia-Romagna regional monitoring network (Italy).

ARPA Emilia Romagna created, in 1997, a regional network for the continuous monitoring of the mutagenicity of PM(2.5) by short-term mutagenicity bioassays to guarantee a constant surveillance on the entire regional territory. The continuous monitoring of the PM mutagenicity provides essential information for a better understanding of the impact of air pollution on the health of the population, and allows one to better judge the efficiency of national and local efforts for urban air quality improvement (use of "green" petrol and ecodiesel, days during which traffic is prohibited, etc.). This article presents the results relating to the Network's activity between September 2000 and December 2002, on PM(2.5) fraction. The organic extracts of PM(2.5) were tested for mutagenicity using Salmonella tester strains TA98 and TA100 with and without metabolic activation (S9). The data obtained on the genotoxicity of air particulate extracts have revealed a constant presence of mutagenic substances adsorbed on particulate matter-with a prevalence of direct-acting mutagens than of promutagens-in a typical seasonal trend featuring higher levels in autumn-winter and lower in warmer periods of the year. In this work the evolution of PM(2.5) mutagenicity was compared with the particles, carbon monoxide (CO) and nitrogen dioxide (NO(2)) concentrations (monthly average); these comparisons revealed a quite good level of agreement on a local basis.