Toward a More Realistic Estimate of Exposure to Chromium and Nickel in Soils of Geogenic And/or Anthropogenic Origin: Importance of Oral Bioaccessibility

To enhance risk assessment for contaminated sites, incorporating bioavailability through bioaccessibility as a corrective factor to total concentration is essential to provide a more realistic estimate of exposure. While the main in vitro tests have been validated for As, Cd, and/or Pb, their potential for assessing the bioaccessibility of additional elements remains underexplored. In this study, the physicochemical parameters, pseudototal Cr and Ni concentrations, soil phase distribution, and oral bioaccessibility of twenty-seven soil samples were analysed using both the ISO 17924 standard and a simplified test based on hydrochloric acid. The results showed wide variability in terms of the concentrations (from 31 to 21,079 mg kg−1 for Cr, and from 26 to 11,663 mg kg−1 for Ni) and generally low bioaccessibility for Cr and Ni, with levels below 20