Deriving health-based soil cadmium thresholds in mining-impacted agricultural regions: An integrated deterministic...

Soil cadmium (Cd) contamination in mining impacted regions poses a critical threat to public health. However, deriving scientifically defensible soil standards is challenging due to complex site-specific dynamics. This study developed a robust risk assessment framework by integrating deterministic and probabilistic (Monte Carlo simulation) models based on 444 paired soil-crop samples from Anhui, China. Our results revealed that bioconcentration factors (BCFs) for rice and rapeseed were significantly suppressed in highly contaminated mining areas, demonstrating a non-linear relationship between soil Cd and plant uptake. Rice ingestion was identified as the dominant exposure pathway (>92 %), with children being the most susceptible group (Hazard Index up to 3.35). Crucially, our probabilistic assessment showed that conventional deterministic methods systematically underestimate risk for the most exposed 15-25 % of the population. From this dual-model framework, we derived a single, site-specific deterministic soil threshold of 0.50 mg kg^-1 and a probabilistic spectrum of thresholds (0.23-0.55 mg kg^-1). The primary contribution of this work is a transferable methodology that enables policymakers to develop flexible, risk-informed soil management strategies tailored to the unique biogeochemistry and population characteristics of a specific region.