Platinum Group Element Enrichment in Road Dust and Their Human Bioaccessibility

Road dust is enriched with a range of metals and metalloids of human health concern, including technology-critical elements, such as the automotive exhaust catalysts platinum (Pt), palladium (Pd) and rhodium (Rh). To date, inhalable road dust particle size fractions have not been fully characterized in terms of their elemental composition or bioaccessibility upon uptake in the human lung. The goal of this study was to examine platinum group element (PGE) enrichment patterns and bioaccessibility in road dust particle size fractions of physiological relevance for human respiratory exposures (<10 microns). Inhalable particle size and bulk road dust samples (n=65) were collected in cooperation with the City of Toronto. Total (bulk) PGE concentrations were measured in dust samples using NiS fire-assay-INAA. The lung simulant, Gamble’s solution, was used to extract the bioaccessible fractions of PGE (n=16). Metal concentrations were measured in extracts with ICP-MS.Using a laser diffraction par...