Oxidative potential of mineral dust particles: A focus on chemical components and cell-free assay

Oxidative potential (OP) assays are feasible methods to comprehensively understand how exposure to atmospheric chemical components can influence the formation of reactive oxygen species (ROS) in the human body. The increase of ROS concentration can enhance the oxidation of numerous components, such as of the DNA, proteins, and lipids, which cause mutations and cell damage, leading to respiratory illness. According to available studies, the mechanisms of PM-related health effects are not totally understood. The aim of the present study is to assess which available assays are suitable for evaluating the OP of different Mineral dust (MD) samples and what limitations may apply to either method. Cell-free assays are assessed including methods based on the interaction of ascorbic acid (AA) and dithiothreitol (DTT) with soluble aerosol chemical components.

Oxidative potential experiments were carried out on both commercially available standard solutions, ultrapure water (DTT) and buffer solution (AA), as well as on soluble extracts of one-quarter filter samples obtained using both shaking and ultrasound procedures. Most limitations were related to high concentrations of transition metals in the buffer solution composition, which was treated using Chelex 100 sodium resin. Transition metals were strongly correlated to both methods, such as Ti, Cr, V, and Mn for DTT assays, and Fe, and Sr for AA assay. The mineral dust OP values were lower than the OP of particulate matter samples from urban metropolitan centers. Such results could be related to the fewer metal and quinone concentrations in the MD samples in comparison to the urban sample. DTT assay has shown more sensibility to the MD content compared with AA chemical procedure. These assays contribute to building an impact-evaluation model for assessing the variation of MD OP based on its different chemical composition.