Environmental genotoxicity assessment of nanoparticles using human airway epithelial model

Because of the growing use of nanoparticles (NPs) in manufacturing consumer goods, it is essential to identify new in vitro approaches to assess their toxicity and improve risk assessment. Humans are exposed to NPs from contaminated aerosol via multiple routes, such as inhalation, ingestion, and dermal absorption. Human airway epithelial cells are a promising tool for assessing the genotoxicity of NPs in vitro. This study aims to evaluate the genotoxic effects of titanium dioxide (TiO₂), zinc oxide (ZnO), and silver oxide (AgO) NPs on human bronchial/tracheal epithelial cells (HBTECs) using the comet assay. The exposure duration was set to 24 h, and two- (2D) and three-dimensional (3D) spheroid models were used. The genotoxicity of TiO₂ NPs in 2D and 3D HBTEC cells was not statistically significant based on the concentration points examined in vitro. ZnO NPs at concentrations ranging from 10 to 50 μg/mL, when exposed to 2D HBTEC cultures for 24 h, did not show any genotoxic effects. However, genotoxicity was observed at higher concentrations. In contrast, treatment of 2D HBTEC cultures with AgO NPs increased the percentage of tail DNA damage from 50 to 100 μg/mL in a concentration-dependent manner. Within a controlled laboratory environment, ZnO and AgO NPs exhibited a reduction in the length of the tail in 3D spheroid cells. When evaluating genotoxicity, spheroids (3D) represent in vivo-like cell behavior more accurately than monolayer cultures (2D). Collectively, our findings illustrate the harmful effects of NPs on genetic material and emphasize the significance of employing cell culture models to evaluate the risk of toxicity.