Zhao et al. 2022 — Pb and Cd in China’s Sixth Total Diet Study
The Sixth China Total Diet Study (TDS), conducted 2016–2019 across 24 provincial-level administrative divisions covering approximately 86% of the Chinese population, measured dietary exposure to lead (Pb) and cadmium (Cd) in 288 composite samples spanning 12 food categories. The study found that mean dietary Pb intake for Chinese adult males (0.318 µg/kg body weight per day) was within acceptable levels by margin of exposure (MOE) analysis, while mean Cd intake (8.26 µg/kg body weight per month, 33% of PTMI) was broadly acceptable but exceeded the PTMI in Hunan Province (120% of PTMI) driven by exceptionally high Cd in cereals (primarily rice). This represents a significant national dietary surveillance finding from the NHC Key Laboratory of Food Safety Risk Assessment at China’s National Center for Food Safety Risk Assessment (CFSA).
Key numbers
Detection rates and food concentrations (µg/kg):
| Food category | Pb detection rate (%) | Pb mean | Pb range | Cd detection rate (%) | Cd mean | Cd range |
|---|---|---|---|---|---|---|
| Cereals | 100 | 11.9±20.6 | 1.2–47.6 | 100 | 14.5±33.5 | 3.0–83.2 |
| Legumes | 100 | 12.9±15.5 | 4.7–34.9 | 100 | 16.8±18.5 | 4.5–41.9 |
| Potatoes | 100 | 11.2±16.2 | 0.4–35.5 | 100 | 11.1±14.4 | 2.3–30.8 |
| Meats | 100 | 10.3±15.3 | 1.3–28.9 | 100 | 2.4±3.7 | 0.6–8.1 |
| Eggs | 95.8 | 9.7±12.4 | <LOD–25.3 | 100 | 1.1±4.0 | 0.1–9.0 |
| Aquatic foods | 100 | 14.1±19.4 | 2.2–37.4 | 100 | 16.9±46.3 | 0.9–83.8 |
| Dairy products | 95.8 | 1.6±2.6 | <LOD–4.8 | 50.0 | 0.1±0.5 | <LOD–0.9 |
| Vegetables | 100 | 15.7±24.4 | 3.6–54.0 | 100 | 12.5±19.1 | 2.9–46.6 |
| Fruits | 100 | 5.0±8.6 | 0.3–19.1 | 100 | 0.9±1.7 | 0.3–4.3 |
| Sugar | 100 | 9.7±30.4 | 0.4–75.0 | 100 | 3.4±19.5 | 0.1–49.0 |
| Beverages & water | 100 | 1.9±2.7 | 0.2–5.7 | 50.0 | 0.1±0.4 | <LOD–0.9 |
| Alcohol | 100 | 1.9±3.4 | 0.1–7.1 | 66.7 | 0.35±1.3 | <LOD–2.9 |
Analytical LODs: Pb = 0.08 µg/kg; Cd = 0.05 µg/kg. Below-LOD values set to 1/2 LOD per WHO guidance.
Dietary intake — lead:
- National mean Pb intake: 0.318 µg/kg body weight/day (range across 24 PLADs: 0.103–0.746 µg/kg BW/day)
- Northern regions: 0.326 µg/kg BW/day; Southern regions: 0.310 µg/kg BW/day
- MOE values: 1.6–11.7 across 24 PLADs (BMDL0.1 = 1.2 µg/kg BW/day for 1 mmHg systolic BP increase); all MOE >1, indicating acceptable risk
- Top dietary Pb sources (nationally): cereals 43.5%, vegetables 29.0%, beverages/water 9.8%
- Regional variation: in southern China, cereals 31% and vegetables 37.1%; in northern China, cereals 50.6% and vegetables 19.7%
Dietary intake — cadmium:
- National mean Cd intake: 8.26 µg/kg BW/month (range: 2.60–30.02 µg/kg BW/month; 10.4%–120% of PTMI = 25 µg/kg BW/month)
- Southern regions: 11.96 µg/kg BW/month; Northern regions: 4.55 µg/kg BW/month
- Only Hunan Province exceeded PTMI: 120% of PTMI
- Hunan cereals Cd: 83.17 µg/kg (vs. national mean 14.45 µg/kg; 5.8× higher)
- Top dietary Cd sources: cereals 56.3%, vegetables 26.6%
- Compared to Fifth TDS: Cd intake decreased 47%, Pb intake declined gradually over latter three TDS cycles
Sixth TDS compared to other countries (Supplementary Table S1):
| Country | Pb mean (µg/kg BW/day) | Cd mean | Population |
|---|---|---|---|
| France | 0.2 | 0.16 µg/kg BW/day | adult |
| USA | 0.047–0.28 | 0.2 µg/kg BW/day | whole population |
| UK | 0.09–0.10 | 0.14–0.17 µg/kg BW/day | adult |
| Australia | 0.018–0.16 | 2.0–5.5 µg/kg BW/month | 19+ years |
| Canada | 0.13 | 0.2 µg/kg BW/day | 40–64 years male |
| China (5th TDS) | 0.316 | 8.3 µg/kg BW/month | adult |
| China (6th TDS) | 0.318 | 8.26 µg/kg BW/month | adult |
China’s Pb and Cd intake levels remain higher than comparable TDS data from France, UK, USA, Australia, and Canada.
Methods (brief)
ICP-MS for Pb and Cd determination (LOD: 0.08 and 0.05 µg/kg respectively). Sixth TDS covered 24 PLADs (86% of Chinese population), with food samples collected from local markets, cooked by local methods, then composited by weight proportional to consumption to form 12 composite samples per PLAD (288 composite samples total). Food consumption data from >40,000 individuals via 3-day household dietary surveys and 24-hour recall. Point estimate method used for dietary intake calculations. Pb risk assessed by MOE approach (BMDL0.1); Cd risk assessed against PTMI (25 µg/kg BW/month, replacing PTWI at 73rd JECFA meeting). All Pb and Cd levels below China GB 2762–2017 maximum levels.
Implications
Certification: Vegetables are a major contributor to both Pb (29% of national intake) and Cd (26.6% of national intake) exposure in China. The Hunan Province finding (cereals Cd 83.17 µg/kg, 5.8× national mean) illustrates the geographic concentration of Cd risk in rice-dominant southern China — directly relevant to HMT&C cereal/grain ingredient sourcing specifications. The north-south dietary divergence (rice south, wheat north) is a key geographic factor for Cd burden.
Courses: The Sixth TDS provides an authoritative national benchmark for contextualizing product-category Pb and Cd risks within total dietary exposure. The declining trend across TDS cycles (Cd down 47% from Fifth TDS) demonstrates that regulatory pressure and pollution control can reduce dietary metal burden.
App: Vegetables contribute 29% of dietary Pb and 26.6% of dietary Cd in the Chinese diet — one of the highest vegetable contributions to metal exposure reported in any national TDS. Legumes and aquatic foods are also high-Cd categories. Cereal Cd is strongly geography-dependent (Hunan ≫ northern China).
Microbiome: Rice-dominant southern diet pattern correlating with higher Cd exposure is relevant to population-level gut microbiome metal exposure gradients.