This study mapped the spatial distribution of cadmium (Cd) across 334 grain samples (rice, corn, wheat) collected from karst farming regions of Guizhou province, China, a zone known for elevated natural Cd background due to karst geology. Cadmium concentrations ranged widely, and exceedance rates against the Chinese national standard (GB 2762-2017: 0.2 mg/kg for rice, 0.1 mg/kg for corn and wheat) were substantial, especially in wheat (45.1%). The paper also addressed fluorine, but Cd is the primary heavy-metal finding of wiki relevance.
Key numbers
Sample n: 334 total (113 rice, 119 corn, 102 wheat). Cadmium ranges: rice 0–463 µg/kg (mean not extracted from abstract, flagged for table review); corn 0–307 µg/kg; wheat 12–537 µg/kg. Exceedance rates against Chinese standard (0.2 mg/kg rice, 0.1 mg/kg corn/wheat): rice 11.6%, corn 13.5%, wheat 45.1%. Method: ICP-MS. Jurisdiction: Guizhou province, CN.
Methods (brief)
ICP-MS on acid-digested grain samples. Spatial mapping using GIS-based interpolation across karst regions. Risk assessment using hazard quotient (HQ) and cancer risk methods. n=334 samples across three crops.
Implications
Certification: Guizhou wheat at 45.1% exceedance rate against Chinese 0.1 mg/kg limit is a high-risk origin for wheat-containing products. Corn exceedance at 13.5% is also significant. Sourcing decisions for grain ingredients should screen for Guizhou karst origin. Courses: Illustrates geology-driven (karst) Cd contamination vs. industrial sources; strong case study for origin-specific supply chain risk. App: Supports geographic_breakdown entries for Cd in rice, corn, and wheat; Guizhou karst region warrants elevated risk flagging.