Cytotoxicity of Quartz and Montmorillonite in Human Lung Epithelial Cells (A549)

In this study, A549 cell viability, extracellular activities of lactate dehydrogenase (LDH), and tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 levels were investigated after incubation with quartz (KWC-Q4 and KWC-Q3), Nano-SiO2, and KWC-M; the micronucleus test and comet assay were carried out to evaluate the genotoxicity. The results showed there were significant differences in the cell death rate and extracellular LDH activities compared with the control group, and showed a good linear relationship in certain concentration range. All mineral particles tested can induce the increase of TNF-alpha after incubation with mineral powders at 200 mu g/mL for merely 3 h and also induce significant increase of IL-6 for 24 h; the results indicated that inflammatory reaction can be triggered by the exposure of KWC-Q4, KWC-Q3, Nano-SiO2, and KWC-M. The results of micronucleus test showed FMN (Frequency of micronucleus number) listed as Nano-SiO2>KWC-Q3>KWC-Q4. There was no significant FMN increase of KWC-M compared with the control group, which maybe resulted from its high cell mortality at low concentration. The comet assay confirmed the genotoxicity of all tested samples, and the DNA damage: KWC-M>Nano-SiO2>KWC-Q4>KWC-Q3.