Genotoxicity induced in vitro by water-soluble indoor PM fractions in relation to heavy metal concentrations.

The aim of the present study was to examine the genotoxicity induced by water-soluble fractions of particulate matter (PM) and its potential relation with heavy metals. For this purpose, the genotoxicity induced on human peripheral lymphocytes by water-soluble PM (particles with aerodynamic diameter ≤ 2.5 μm) collected from the indoor air of various workplaces in Greece (n = 20), was examined by the Sister Chromatid Exchange (SCE) induction assay and assessed in relation to the concentrations of the heavy metals Cu, Pb, Mn, Ni, Co, Zn, Cr, and Cd. The number of SCEs per metaphase (SCEs/metaphase), as an indicator of genotoxicity, the proliferation rate index (PRI), as an indicator of cytostaticity, and the mitotic index (MI), as an indicator of cytotoxicity, were measured and assessed in three water-soluble fractions of PM: the total water-soluble fraction WS (filtered through 0.45 μm), the dissolved fraction WS (filtered through 0.22 μm), and the non-chelexed dissolved fraction WS (filtered through Chelex-100 resin). Results showed statistically significant number of SCEs/metaphase in all water-soluble PM fractions in relation to the control with large variabilities across the workplaces as a result of variations in indoor conditions, sources, and/or activities. The concentrations of genotoxicity were evaluated in terms of mass-normalized genotoxicity (SCEs/mg PM), that represents the genotoxic potency of particles, and air volume-normalized genotoxicity (SCEs/m air), that reflects the inhalation risk for people working or spending much time in these microenvironments. Correlation and linear regression analyses were further employed in order to investigate the potential relationships between genotoxicity and the water-soluble concentrations of PM-bounded heavy metals. According to the results, the highest mass-normalized genotoxicity values were found for PM from the photocopying center, whereas the highest air volume-normalized genotoxicity was found in tavern-2. Significant positive correlations between the genotoxicity and water-soluble metals were derived, highlighting the role that heavy metals play in the genotoxicity of indoor PM. Among the targeted metals, Zn and Pb were found to be good predictors of the genotoxicity of water-soluble PM