Innovative Benefit–Risk-Value Assessment for Cadmium and Selenium Coexposure in Black Shale Regions

The coexistence of cadmium (Cd) and selenium (Se) in black shale regions poses challenges for assessing health risks in local populations. Traditional risk assessments focus exclusively on single Cd contamination and total dietary intake, neglecting the interactions between them and the digestion and adsorption processes in the human body. This study established a novel benefit-risk-value (BRV) criterion to assess coexposure effects. Besides, we compared existing single-element risk assessment criteria and evaluated changes in risk before and after the incorporation of bioaccessibility using in vitro simulation. Rice constituted the major exposure source for Cd, whereas Se intake primarily relied on meat and rice. Integrating bioaccessibility with traditional risk assessment criteria significantly reduced the health risks associated with Cd exposure, while revealing notable Se deficiency in adults and seniors. Different from traditional models, BRV analysis indicated that children were safe from Cd and Se exposure, whereas adults and the seniors suffered from Se deficiency. As a biomarker, hair further validated the feasibility of the new standard. Correlation analysis demonstrates an age-dependent decline in the molar ratio of Se to Cd in hair samples. This study reveals that the mitigation of Se on Cd toxicity may contribute to Se deficiency.