Coal fly ash and mineral dust for toxicology and particle characterization studies: Equipment and methods for PM2.5- and PM1-enriched samples

Laboratory methods to produce particle samples from known, reproducible sources with sufficient mass to perform both detailed characterization and replicated in vitro toxicological assays are described. These samples are being used to study the ability of inhalable particles to produce abnormal concentrations of intracellular iron, resulting in the production of reactive oxygen species in cultured airway epithelial cells. Bulk samples of size fractionated particles from laboratory-generated coal fly ash and from simulated fugitive mining tailings and road dust were collected as surrogates for important sources of iron-bearing particles in the ambient air. An Andersen cascade impactor was used to produce particle samples enriched in three size ranges: >10 μm, 10-2.5 μm, and <2.5 μm aerodynamic diameter. A multijet preseparator and rectangular slot virtual impactor were used to produce a fraction enriched in particles below 1 μm. Data on the particle production conditions, production rates, and particle sample quality are provided to illustrate the feasibility of the experimental approach. The amount of iron mobilized from particles by a physiologically-relevant chelator does not correlate with the total iron. This supports the hypothesis that particle characteristics and iron speciation are important for the production of abnormal iron concentrations in cultured type A549 human airway epithelial cells. Comparison of results obtained with these surrogate particles to previous work with urban particulate standard reference materials (SRM 1648 and SRM 1649) suggests particle sources and size fractions that should be emphasized for detailed characterization of particle morphology and mineralogy.