Alumina nanoparticles size and crystalline phase impact on cytotoxic effect on alveolar epithelial cells after simple or HCl combined exposures.

Applications using alumina nanoparticles (AlO NPs) have incredibly increased in different fields of activity. In defense and aerospace fields, solid composite propellants use leads to complex combustion aerosols emissions containing high concentrations of AlO NPs and hydrogen chloride gas (HCl). To better characterize potential hazard resulting from exposure to these aerosols, this study assesses cytotoxic effects of mixtures containing both compounds on human pulmonary alveolar epithelial cells (A549 cell line) after 24 h exposures. After all co-exposures cell viability was >80%. However co-exposures decrease normalized real-time cell index. Significant decreases of intracellular reduced glutathione pool were also observed after co-exposures to γ-10 nm or γ/δ-13 nm AlO NPs and HCl. Co-incubations with γ/δ-13 nm or γ-500 nm AlO particles and HCl induced significant DNA double-strand breaks increases. Moreover all co-exposures and HCl alone disrupted cell cycle (increased G1 phase cells). Transmission Electron Microscopy (TEM) observations revealed γ/δ-13 nm AlONPs adsorption and internalization in cell cytoplasm only, suggesting indirect genotoxic effects. According to our results AlO particles/HCl mixtures can induce cytotoxic effects and AlO size and crystallinity are two main parameters influencing cytotoxic mechanisms.