Integrated assessment of chromium exposure risk from agricultural soils using chemical extraction, in vitro simulation, and mouse bioassay

Chromium (Cr) contamination in soil poses significant human health risks due to its toxicity and environmental persistence. In this study, the bioaccessibility of Cr from three aged agricultural soils was assessed using an in vitro (physiologically based extraction test, PBET) method. Simultaneously, single extraction methods (0.43 M HNO₃ and EDTA) and in vivo (mouse model) bioassay were used to assess the health effects of Cr exposure. The results showed that Cr bioaccessibility in the gastric phase ranged from 0.7 % to 21.7 %, and was 1.3–1.8 folds higher in the small intestinal phase. Among the three soils, the weakly alkaline soil exhibited the highest bioaccessibility in both phases. Significant correlations (R² = 0.74–0.95) were found between extractable Cr (%) and Cr bioaccessibility, particularly for 0.43 M HNO₃. In vivo bioassays determined relative bioavailability (based on kidneys or liver), absolute bioavailability, and Cr concentration in tissues, revealing that Cr tended to be excreted rather than accumulated in tissues. Additionally, Cr exposure altered gut microbiota composition, notably increasing Lactobacillaceae while decreasing Muribaculaceae, Prevotellaceae and Rikenellaceae. This study highlighted that single extraction methods could predict in vitro bioaccessibility, which facilitates the rapid and accurate assessment of risks from oral intake of Cr-contaminated soils.