Bioaccessibility of Arsenic and Lead in Polluted Soils Using Three In-vitro Gastrointestinal Simulation Models

In human health risk assessment (HHRA), oral ingestion of soil can be a major route of exposure to many immobile soil contaminants. Development and validation of in vitro assays is currently being undertaken to avoid overestimation of pollutants absorbed by the human body when calculating total pollutant concentrations in HHRA. In this study, arsenic (As) and lead (Pb) bioaccessibility in polluted Australian soils (n = 6) was assessed using three in vitro assays: a physiologically based extraction test (PBET), Solubility/Bioavailability Research Consortium Assay (SBRC) and Unified Bioaccessibility Research Group Of Europe Method (UBM). In vitro results were compared among these three assays and the possible causes of their differences were discussed. A bioaccessibility-corrected HHRA was then conducted. Bioaccessibility varied greatly among metal(loid)s and methods, and extending the three assays from the gastric to the intestinal phase generally resulted in decreased As and Pb bioaccessibility. Using these bioaccessibility values, both hazard index (HI) and carcinogenic risk (CR) were calculated, and were found to be higher than threshold values in most samples, indicating a potential health risk to local inhabitants.