Cadmium accumulation in different types of vegetable across China: Dietary exposure risk, and a novel method for...

Cadmium (Cd) contamination in vegetables poses a potential risk to human health; thus an accurate soil Cd threshold is crucial for early warning to ensure safe production. In this study, a national-scale dataset of Cd contents in agricultural soils and vegetables in China was compiled to assess the dietary exposure risk, and a hybrid approach combining conditional inference trees (CITs) and species sensitivity distribution (SSD) was established to derive soil Cd thresholds. The results showed that amaranth, butterhead lettuce, Chinese cabbage, coriander, and garlic had higher Cd accumulation ability among 34 species studied. An optimal vegetable consumption ratio (50 % leafy, 30 % root-stalks, 10 % solanaceous, 10 % legume) was recommended to minimize health risks from Cd exposure. The CITs revealed that soil pH significantly affects Cd accumulation of leafy vegetables, with critical pH values of 5.34 and 6.98. Using the CITs-SSD model, priority-protection soil Cd thresholds were derived: 0.18-1.24 mg/kg for leafy, 0.54 mg/kg for root-stalk, 0.43 mg/kg for solanaceous, and 0.93 mg/kg for legume vegetables. After accuracy assessment, these thresholds reduced the misjudgment rate by 5.8 %-16.7 % compared with current national standards. This study presents a novel approach for establishing soil Cd criteria and provides scientific support for ensuring vegetable safety in Cd-contaminated areas.