Integrating arsenic bioaccessibility uncertainty and human exposure variability for setting up site-specific remedial goals

Abstract

Arsenic is a highly toxic soil contaminant, which is a major public concern. The universal health risk models and global efforts on deriving remedial goals for arsenic-contaminated soil have not yielded the desired or very satisfactory results. In this study, we developed a probabilistic risk-assessment method with a two-dimensional Monte Carlo simulation by integrating arsenic bioaccessibility uncertainty and human exposure variability. We found that arsenic bioavailability significantly varied in gastric (0.59–43.20%) and intestinal (0.72–44.22%) phases owing to arsenic fractions and total iron content. We showed that the mean carcinogenic risk at the 95th percentile was 7.64 × 10−5, exceeding the acceptable risk level (10−6), and the non-carcinogenic risk was 3.48, exceeding the acceptable risk level (1.0). Finally, we recommend 25.72 mg/kg as a remedial goal for the site based on this new approach. Overall, this study demonstrated that the improved method effectively mitigates the conservative nature of the existing regulatory approach. The improved approach helps prevent unnecessary remediation actions, supporting SDG 13 climate action by lowering pollutant and carbon emissions.