Bioaccessibility of As, Cu, Pb, and Zn in mine waste, urban soil, and road dust in the historical mining village of KaAk, Czech Republic

Historical mining activities in the village of KaAk (in the northern part of the Kutna Hora ore district, Czech Republic) produced large amounts of mine wastes which contain significant amounts of metal(loid) contaminants such as As, Cu, Pb, and Zn. Given the proximity of residential communities to these mining residues, we investigated samples of mine waste (n = 5), urban soil (n = 6), and road dust (n = 5) with a special focus on the solid speciation of As, Cu, Pb, and Zn using a combination of methods (XRD, SEM/EDS, oxalate extractions), as well as on in vitro bioaccessibility in simulated gastric and lung fluids to assess the potential exposure risks for humans. Bulk chemical analyses indicated that As is the most important contaminant in the mine wastes (similar to 1.15 wt%), urban soils (similar to 2900 mg/kg) and road dusts (similar to 440 mg/kg). Bioaccessible fractions of As were quite low (4-13%) in both the simulated gastric and lung fluids, while the bioaccessibility of metals ranged between < 0.01% (Pb) and 68% (Zn). The bioaccessibilities of the metal(loid)s were dependent on the mineralogy and different adsorption properties of the metal(loid)s. Based on our results, a potential health risk, especially for children, was recognized from the ingestion of mine waste materials and highly contaminated urban soil. Based on the risk assessment, arsenic was found to be the element posing the greatest risk.