Peculiarities of toxic effects produced by aluminum oxide nano- and microparticles under multiple inhalation exposure

Introduction. Aluminum oxide nanoparticles (Al2O3 NPs) are widely used in nanotechnologies employed in various branches including chemical, food, and medical industry and perfume and cosmetics production. This high demand for Al2O3 NPs, given the wide-scale development of nanoindustries, can, in its turn, lead to ambient air pollution that creates public health risks under long-term exposure to it. Given that, it seems relevant to perform profound investigation with its focus on pathogenetic features of toxic effects produced by these nanoparticles and comparatively analyze them with effects produced by a micro-sized chemical analog under inhalation exposure to introduce more effective prevention. Materials and methods. We examined chemical properties of Al2O3, nano- and microparticles (MPs) in an experiment on Wistar rats, comparatively analyzed the results and described pathogenetic features of toxic effects produced by the examined particles under multiple inhalation exposure. Results. The examined samples were a nanomaterial judging by such parameters as particle size, shape, surface area, and total pore volume. They differed substantially from their micro-sized analog. Exposure to Al2O3 NPs causes more pronounced changes in the behaviour of rats relative to MPs. Under exposure to Al2O3 NPs, aluminum concentrations were statistically significantly by 1.62–55.2 times higher in the lungs, liver, brain and blood. The concentration of the examined elements was by 1.55–7.65 times higher in these organs as compared to exposure to the micro-sized particles. Exposure to Al2O3 NPs induced changes in biochemical indicators of negative effects against the control (exposure to micro-sized particles). We established higher activity of ALT, AST, AP, LDH, and elevated levels of direct bilirubin, GABA, glutamine acid, and MDA against the same indicators in the control group. Pathomorphological changes were identified in the lungs, brain, heart, and liver under exposure to Al2O3 NPs whereas exposure to the micro-sized analog induced such changes only in the lungs. Exposure to NPs induced more apparent changes in tissue structures in many organs. Limitations. The study involved only multiple inhalation exposure to Al2O3 NPs and MPs in an experiment on Wistar rats. Conclusion. Al2O3 NPs are more toxic than their micro-sized chemical analog; this is evidenced by a greater number of organs where bioaccumulation occurs, more apparent pathomorphological changes and pathological functional disorders. The study results should be considered when developing hygienic recommendations aimed at preventing and minimizing negative effects produced by Al2O3 NPs on human health.