Exposure to Lead and Cadmium in the Sixth Total Diet Study

Overview

Zhao and colleagues report the lead and cadmium exposure component of the Sixth China Total Diet Study, covering 288 composite food samples across 24 provincial-level administrative divisions (PLADs) and ~86% of the Chinese population. Pb and Cd were quantified by ICP-MS in 12 food categories. The national mean dietary intake for adult males was 0.318 µg/kg bw/day for Pb (MOE > 1 in all 24 PLADs) and 8.26 µg/kg bw/month for Cd (33.0% of PTMI nationally); Hunan Province adult males exceeded the PTMI for Cd at 120%, primarily driven by cereals (rice).

Key numbers

Six TDS round (2016–2019); 24 PLADs; 12 food categories per PLAD → 288 composite samples total (Foreword + article p. 176).
Pb LOD 0.08 µg/kg; Cd LOD 0.05 µg/kg by ICP-MS; samples below LOD set to 1/2 LOD per WHO method (p. 176).
Detection rate: 99.3% for Pb; 88.9% for Cd across 288 PLAD composites (p. 176).
National mean (µg/kg) by food category — Pb (mean ± SD, min–max): Cereals 11.9±20.6, 1.2–47.6 (DR 100%); Legumes 12.9±15.5, 4.7–34.9 (100%); Potatoes 11.2±16.2, 0.4–35.5 (100%); Meats 10.3±15.3, 1.3–28.9 (100%); Eggs 9.7±12.4, <LOD–25.3 (95.8%); Aquatic foods 14.1±19.4, 2.2–37.4 (100%); Dairy products 1.6±2.6, <LOD–4.8 (95.8%); Vegetables 15.7±24.4, 3.6–54.0 (100%); Fruits 5.0±8.6, 0.3–19.1 (100%); Sugar 9.7±30.4, 0.4–75.0 (100%); Beverages & water 1.9±2.7, 0.2–5.7 (100%); Alcohol 1.9±3.4, 0.1–7.1 (100%) (Table 1, p. 177).
National mean (µg/kg) by food category — Cd (mean ± SD, min–max): Cereals 14.5±33.5, 3.0–83.2 (DR 100%); Legumes 16.8±18.5, 4.5–41.9 (100%); Potatoes 11.1±14.4, 2.3–30.8 (100%); Meats 2.4±3.7, 0.6–8.1 (100%); Eggs 1.1±4.0, 0.1–9.0 (100%); Aquatic foods 16.9±46.3, 0.9–83.8 (100%); Dairy products 0.1±0.5, <LOD–0.9 (50.0%); Vegetables 12.5±19.1, 2.9–46.6 (100%); Fruits 0.9±1.7, 0.3–4.3 (100%); Sugar 3.4±19.5, 0.1–49.0 (100%); Beverages & water 0.1±0.4, <LOD–0.4 (50.0%); Alcohol 0.35±1.3, <LOD–2.9 (66.7%) (Table 1, p. 177).
Highest mean Pb foods (µg/kg): vegetables 15.7; aquatic foods 14.1; legumes 12.9; cereals 11.9; potatoes 11.2.
Highest mean Cd foods (µg/kg): aquatic foods 16.9; legumes 16.8; cereals 14.5; vegetables 12.5; potatoes 11.1.
Mean dietary Pb intake for Chinese adult male 0.318 µg/kg bw/day (range 0.103–0.746 across 24 PLADs); north 0.326, south 0.310 µg/kg bw/day.
MOE for Pb computed against BMDL₀.₁ = 1.2 µg/kg bw/day; MOE > 1 in all 24 PLADs (range 1.6–11.7) — within acceptable level for all adult-male populations.
Top 3 dietary Pb sources nationally: cereals 43.5%; vegetables 29.0%; beverages and water 9.8%. Northern PLADs: cereals 50.6%, vegetables 19.7%. Southern PLADs: cereals 31%, vegetables 37.1%.
Mean dietary Cd intake for Chinese adult male 8.26 µg/kg bw/month (range 2.60–30.02 across 24 PLADs); southern regions 11.96, northern regions 4.55 µg/kg bw/month.
Cd dietary intake as % PTMI (25 µg/kg bw/month) across 24 PLADs: 10.4% to 120%. Only Hunan adult males (120% PTMI) exceeded the PTMI; primarily driven by cereal contribution of up to 76% (rice).
Hunan cereal Cd mean 83.17 µg/kg = 5.8× national cereal Cd mean (14.45 µg/kg).
Main national Cd contributors: cereals 56.3%; vegetables 26.6%.
Reference daily Pb intakes from prior TDS rounds: TDS1 86 µg/person/day → TDS6 20 µg/person/day; ~47% decrease vs TDS5.
Reference daily Cd intakes from prior TDS rounds: TDS1 13 µg/person/day → TDS6 17 µg/person/day (slight increase trend across rounds 1–5, 47% decrease from TDS5 to TDS6).
Body weight reference: 63 kg standard Chinese man (Foreword Methodology, p. 159).

Methods (brief)

Pb and Cd were quantified in TDS composite food samples by ICP-MS (LOD 0.08 µg/kg Pb; 0.05 µg/kg Cd); values below LOD set to 1/2 LOD per WHO methodology. The Sixth TDS expanded coverage to 24 PLADs (vs. 12 in TDS1–4 and 20 in TDS5), covering ~86% of the Chinese population. Sampling was conducted 2016–2019 via household dietary surveys (n>40,000 individuals; 24-hour recall × 3 consecutive days) at multiple sites per PLAD. Foods cooked using local methods, then composited per food category at 12 PLAD-level samples × 24 PLADs = 288 composites. Point-estimate dietary intake calculated against the BMDL₀.₁ (1.2 µg/kg bw/day) for Pb using MOE approach (JECFA withdrew the PTWI for Pb at the 73rd meeting) and PTMI (25 µg/kg bw/month) for Cd. Adult-male standard body weight 63 kg. The paper does not perform Pb or Cd speciation; both are total elemental concentrations measured by ICP-MS.

Implications

Certification (HMTc): Adds 288 PLAD-level Chinese TDS composite-sample occurrence values for Pb and Cd across 12 food categories on as-consumed cooked basis. Direct evidence for Cereals, Rice (cereal-cohort), Vegetables, and Legumes Pb and Cd profiles in the Chinese diet context. The Hunan cereal Cd hotspot (83.17 µg/kg) is a notable single-region outlier informing regional sourcing risk discussions.
Courses: Useful as a TDS-methodology case study and as evidence of geographic variance (north vs south) for QA, regulatory affairs, and sourcing audiences.
App: Contributes occurrence data points across 12 food categories on as-consumed basis; complements raw-ingredient data with cooked/composite values; informative for risk-by-region modeling against Chinese dietary patterns.

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Exposure to Lead and Cadmium in the Sixth Total Diet Study — China, 2016–2019