Qin et al. 2026 — Spatial coupling of rice cadmium and liver cancer incidence in Guangxi, China
Qin and colleagues conducted a large-scale spatial and individual-level study linking dietary cadmium exposure via rice to hepatocellular carcinoma incidence in Guangxi, a province with unusually high liver cancer rates (crude rate 40.54 per 100,000, roughly 1.46x the Chinese national average). Across 3,754 rice grain samples from 44 counties, the median Cd concentration was 0.07 mg/kg (70 ppb) and the arithmetic mean was 0.12 mg/kg (120 ppb), with spatial clustering of high-Cd rice in central and south-central Guangxi overlapping geographically with liver cancer hot spots. High-Cd counties (Mashan, Gangnan, Hepu, Binyang, Guiping) averaged 0.21–0.24 mg/kg Cd, roughly 2–3x the Guangxi average. Blood Cd levels were significantly higher in liver cancer patients than healthy controls, and a strong correlation (Pearson) was found between county-level rice Cd concentrations and liver cancer incidence rates, with individual rice-to-blood Cd matching suggesting rice consumption as the primary exposure pathway.
Key numbers
Rice grain Cd (n=3,754, 44 counties, Guangxi):
- All-county median: 0.07 mg/kg (70 ppb)
- All-county arithmetic mean: 0.12 mg/kg (120 ppb)
- Guangxi published average: 0.11 mg/kg (comparable to this dataset)
- Chinese national median: 0.06 mg/kg (this dataset is 1.2x national median)
- Chinese regulatory limit (GB 2762-2017, polished rice): 0.20 mg/kg
- Codex Alimentarius limit: 0.40 mg/kg
- Highest-Cd counties: Mashan (mean 0.24), Gangnan (0.23), Hepu (0.23), Binyang (0.22), Guiping (0.21) mg/kg
Five representative study areas (n=175 rice samples):
- Celing Township (northern Guangxi): median 0.39, mean 0.39 mg/kg — highest; exceeds regulatory limit (0.20 mg/kg)
- Changle Town (southern Guangxi): median 0.18, mean 0.18 mg/kg
- Gula Town (central Guangxi): median 0.02, mean 0.03 mg/kg — lowest
- Houlu Township: median 0.08, mean 0.10 mg/kg
- Qingfeng Town: median 0.03, mean 0.05 mg/kg
Blood Cd (patients vs controls, n=105 each, selected from Binyang County, Hengzhou City, Urban Nanning, Qinbei District):
- Hengzhou City patients: median 1.74, mean 2.13 µg/L
- Urban Nanning patients: median 1.42, mean 2.15 µg/L
- (Controls detailed in paper; patients consistently elevated)
Methods (brief)
Rice grain Cd analyzed by ICP-MS following microwave digestion; compliant with GB 2762-2017 and DZ/T 0295-2016 geological industry standard. Analysis by Guangxi Institute of Geological and Mineral Testing. Blood Cd by ICP-MS per group standard TGXAS 727-2024 (22 elements in blood). Spatial analysis in ArcGIS; statistical analysis in SPSS 19.0. Pearson correlation for rice Cd vs liver cancer incidence. Study design limitations: patient/control selection not fully age/sex matched; residual confounding acknowledged.
Implications
Certification: The Guangxi dataset is one of the largest spatial surveys of rice Cd in a high-contamination Chinese province (n=3,754). The Celing Township mean of 0.39 mg/kg for rice grain Cd nearly doubles the Chinese regulatory limit and is close to the Codex limit. This dataset strengthens the evidence that certain Chinese rice supply chains carry Cd well above safe levels and that regional sourcing matters for certification purposes.
Courses: Landmark epidemiological dataset linking a specific dietary exposure pathway (rice-derived Cd) to a health outcome (liver cancer) at provincial scale in China. Demonstrates that rice Cd is not merely a regulatory compliance issue but has measurable public health consequences in high-exposure geographies.
App: Guangxi all-county rice Cd: median 70 ppb, mean 120 ppb; some areas exceed 390 ppb. Use as regional-specific contamination data for Chinese Guangxi-origin rice. Note: applies to polished rice analyzed by wet-weight basis (conventional for food regulatory compliance in China).