CFS 2013 — First Hong Kong Total Diet Study: Metallic Contaminants
The Centre for Food Safety (CFS) of Hong Kong conducted the First Hong Kong Total Diet Study (1st HKTDS) to estimate dietary exposures of the Hong Kong general population and population subgroups to metallic contaminants, and assess associated health risks. This report (Report No. 5 of the TDS series, published January 2013) covers aluminium (Al), antimony (Sb), cadmium (Cd), lead (Pb), methylmercury (MeHg), nickel (Ni), and tin (Sn), with vanadium (V) additionally reported. The study found that dietary exposures to Al, Sb, Cd, Ni, and Sn were all below their respective health-based guidance values for average consumers; about 11% of women of childbearing age had MeHg exposure exceeding the PTWI of 1.6 µg/kg bw, a public health concern for fetal neurotoxicity. Overall, the general adult population was assessed as unlikely to experience major adverse health effects from these contaminants.
Key numbers
- Study design: 1,800 samples of 150 TDS food items, purchased on 4 occasions (March 2010–February 2011); combined into 600 composite samples; analyzed by HR ICP-MS
- Aluminium: mean 30% and high consumers 77% of PTWI (2 mg/kg bw/week); highest levels in deep-fried dough (mean 250 mg/kg), steamed barbecued pork bun (mean 170 mg/kg), oyster (mean 62 mg/kg); leafy vegetables (e.g., Chinese spinach) 25–35 mg/kg; beverages, non-alcoholic were the largest contributor (33%) to Al exposure; vegetables group mean Al 4.1 mg/kg (range ND–45 mg/kg)
- Antimony: dietary exposures 0.3–0.7% (average) and 0.5–1.1% (high) of TDI (6 µg/kg bw/day); well below guidance
- Cadmium: exposures 33% (average) and 75% (high) of PTMI (25 µg/kg bw); all age-gender groups below PTMI
- Lead: no HBGV available; average consumer 0.21 µg/kg bw/day, high consumer 0.38 µg/kg bw/day; below 1.2 µg/kg bw/day (JECFA low-risk level for blood pressure in adults)
- Methylmercury: average consumer 22% and high consumer 82% of PTWI (3.3 µg/kg bw); ~11% of women aged 20–49 exceeded the more protective PTWI of 1.6 µg/kg bw for childbearing-age women
- Nickel: 26% (average) and 48% (high) of TDI (12 µg/kg bw); within guidance
- Tin: 0.2% (average) and 1.1–1.2% (high) of PTWI (14 mg/kg bw); well below guidance
- LODs (general food): Al 100 µg/kg, Sb 1 µg/kg, Cd 2 µg/kg, Pb 2 µg/kg, Ni 20 µg/kg, Sn 10 µg/kg, V 3 µg/kg; LOQ = 5 × LOD for most analytes
- MeHg LOD 0.3 µg/kg, LOQ 1.5 µg/kg (as mercury) in food; 51 TDS food items (204 composites) tested
Methods (brief)
Total Diet Study methodology: food items purchased as consumed, prepared as normally eaten, homogenized into composites. All 600 composites analyzed for Al, Sb, Cd, Pb, Ni, Sn, V by HR ICP-MS after microwave-assisted HNO3 digestion in Teflon high-pressure vessels. MeHg in 204 composites (mainly animal-origin and seafood) by enzymatic hydrolysis, HCl extraction, tetraphenylborate derivatization, iso-octane extraction, GC-ICP-MS with propylmercury internal standard. Sub-LOD treatment: if ≤60% below LOD, medium-bound used (½ LOD); if >60–80%, lower and upper bounds presented. Dietary exposure estimated using EASY exposure assessment system, incorporating FCS consumption data; mean and 95th percentile represent average and high consumers. Note: this report explicitly covers a separate iAs report (1st HKTDS on inorganic arsenic, published February 2012); arsenic speciation data are NOT in this report.
Implications
Certification: The 1st HKTDS provides validated dietary exposure benchmarks for the Hong Kong population across seven metallic contaminants. MeHg results confirm the childbearing-age vulnerability requiring differential guidance. Cd at 33% of PTMI for average consumers provides a baseline for monitoring dietary cadmium trends.
Courses: Strong pedagogical case for Total Diet Study methodology as the most cost-effective approach to estimating population-level dietary exposure. The MeHg data for women of childbearing age is an important vulnerable-population example.
App: This source provides aggregate dietary exposure data by food group for HK, not per-ingredient ppb concentration tables suitable for the app’s contamination_profile format. It can provide context for exposure magnitude but not direct ingredient-level contamination values.
Microbiome: Not applicable.