Han et al. 2024 — Nickel occurrence and dietary exposure in Zhejiang Province, China
This study quantifies nickel concentrations across six food categories in Zhejiang Province, China (2628 samples, 2018–2019) and assesses dietary exposure risk by age group. Beans (n=5) carry exceptionally high nickel levels (mean 3.094 mg/kg, all five samples above the GB 2762-2022 1 mg/kg national limit), while cereal products and fruits stay below the limit. Children aged 0–6 are the only population segment showing unacceptable cumulative exposure (THQ = 1.078) under high-consumption/high-contamination assumptions.
Key numbers
| Category | n | Range (mg/kg) | Mean | P50 | P95 | Detection rate | Overstandard rate |
|---|---|---|---|---|---|---|---|
| Beans total | 5 | 1.22–9.21 | 3.094 | 1.74 | 7.752 | 100% | 100% |
| Beans: Soybean | 1 | 9.21 | 9.21 | 9.21 | 9.21 | 100% | 100% |
| Beans: Mung bean | 2 | 1.22–1.38 | 1.3 | 1.3 | 1.372 | 100% | 100% |
| Beans: Ormosia | 2 | 1.74–1.92 | 1.83 | 1.83 | 1.911 | 100% | 100% |
| Meat and products total | 690 | 0.002–4.99 | 0.258 | 0.084 | 1.006 | 85.8% | 5.07% |
| Meat: Sausages | 316 | 0.002–3.38 | 0.262 | 0.095 | 0.978 | 91.14% | 4.11% |
| Meat: Chinese bacon | 296 | 0.002–3.0 | 0.252 | 0.053 | 1.093 | 78.04% | 6.42% |
| Meat: Other meat product | 7 | 0.010–0.447 | 0.116 | 0.049 | 0.37 | 85.71% | 0% |
| Vegetables and products total | 365 | 0.001–3.35 | 0.185 | 0.078 | 0.639 | 97.81% | 1.64% |
| Vegetables: Legume | 9 | 0.161–3.35 | 0.813 | 0.33 | 2.61 | 100% | 22.22% |
| Vegetables: Tubers | 240 | 0.001–3.19 | 0.215 | 0.118 | 0.751 | 97.08% | 1.67% |
| Vegetables: Pickled | 4 | 0.074–0.251 | 0.167 | 0.172 | 0.247 | 100% | 0% |
| Vegetables: Leafy | 78 | 0.007–0.99 | 0.07 | 0.032 | 0.231 | 100% | 0% |
| Vegetables: Other | 34 | 0.002–0.365 | 0.07 | 0.053 | 0.169 | 97.06% | 0% |
| Aquatic food total | 1405 | 0.001–48.9 | 0.261 | 0.071 | 0.852 | 82.28% | 3.56% |
| Aquatic: Sea fish | 30 | 0.001–1.34 | 0.057 | 0.007 | 0.076 | 43.33% | 3.33% |
| Aquatic: Gastropods | 3 | 0.05–0.35 | 0.194 | 0.183 | 0.333 | 100% | 0% |
| Aquatic: Other processed | 399 | 0.002–4.2 | 0.209 | 0.082 | 0.891 | 89.72% | 4.26% |
| Aquatic: Sea crustacea | 150 | 0.006–0.84 | 0.195 | 0.19 | 0.419 | 99.33% | 0% |
| Aquatic: Freshwater crustacea | 546 | 0.002–48.9 | 0.281 | 0.047 | 0.582 | 78.75% | 2.38% |
| Aquatic: Freshwater fish | 145 | 0.002–10.5 | 0.149 | 0.01 | 0.422 | 53.1% | 1.38% |
| Aquatic: Canned fish | 82 | 0.002–19.1 | 0.647 | 0.204 | 1.539 | 92.68% | 13.41% |
| Aquatic: Shellfish | 50 | 0.056–1.53 | 0.484 | 0.308 | 1.279 | 100% | 12% |
| Cereal products | 27 | 0.025–0.696 | 0.136 | 0.102 | 0.302 | 100% | 0% |
| Fruits | 136 | 0.004–0.75 | 0.097 | 0.059 | 0.293 | 100% | 0% |
Sampling: 11 cities, 2018–2019, multistage random; 5 categories sampled at field/market/online stages. Body weights and daily intakes by age group for consumption modelling are tabulated below.
| Age group | Body weight (kg) | Notes |
|---|---|---|
| 0–6 years | 18.988 | n=4173 of 19,000 (16.60%) population subset |
| 7–10 years | 35.233 | |
| 11–17 years | 61.639 | |
| 18–59 years | 60.170 | 70.14% of survey |
| ≥60 years | 52.652 | 13.26% of survey |
Daily Ni intake (µg/kg-bw/d), Mode D (P95 concentration × P95 consumption), by age group:
| Age group | Total Ni intake (Mode D) | THQ (Mode D) |
|---|---|---|
| 0–6 years | 21.57 | 1.078 (unacceptable) |
| 7–10 years | 12.680 | 0.634 |
| 11–17 years | 8.638 | 0.432 |
| 18–59 years | 9.923 | 0.496 |
| ≥60 years | 11.4 | 0.57 |
Beans and vegetables/vegetable-products were the main sources of dietary Ni exposure (>50% of total for low-consumption modes A and C; vegetables dominate in high-consumption modes B and D). USEPA reference dose used: 20 µg/kg-bw/d.
Methods
Inductively Coupled Plasma Mass Spectrometry (NexION 300D, PerkinElmer) on samples microwave-digested with nitric acid (6–8 mL) and hydrogen peroxide (1 mL) per the Mars-6 microwave program (120°C/150°C/190°C three-step). Sample mass 0.5 g, final volume 25 mL. LOD: 3.5 µg/kg for vegetables and fruits, 3.0 µg/kg for other matrices. Samples below LOD set to ½ LOD. Quality control: one QC sample per ten samples, certified reference materials, standard addition recovery. Total nickel only — no speciation between Ni(II) and Ni(0) or Ni carbonyls.
Risk assessment used USEPA target hazard quotient method (THQ = EDI / RfD; RfD = 20 µg/kg-bw/d). Four consumption modes A–D corresponding to median/P95 combinations of concentration × consumption. Statistical analyses: chi-squared test for detection/overstandard rates; Anderson-Darling normality test; Wilcoxon rank-sum test for skewed distributions.
Implications
Certification: Beans are a high-Ni outlier among Chinese food categories — all five sampled bean species exceeded the GB 2762-2022 1 mg/kg national standard. Canned fish (13.41% overstandard rate, P95 1.539 mg/kg) and shellfish (12% overstandard, P95 1.279 mg/kg) are the other concentrated Ni vectors. HMTc Ni thresholds for legumes, canned fish, and shellfish should anchor on these distributions; for fresh leafy vegetables and fruits the same dataset supports tight thresholds well below the 1 mg/kg national standard. The Cat 1 infant/child food pages should incorporate the 0–6 year THQ finding (1.078) as evidence that Ni cumulative exposure crosses the safety threshold for the youngest population segment under realistic consumption modes.
Courses: This paper is a clean teaching example of how ICP-MS dietary-intake studies combine concentration data with consumption surveys to produce age-stratified exposure estimates, and how the THQ method aggregates risk across food categories.
App: Beans, canned fish, and shellfish contribute disproportionately to per-serving Ni risk relative to their consumption frequency. The app’s per-ingredient Ni risk scoring for Chinese-market or East-Asian-dietary contexts should weight these three categories higher than the average.
Microbiome: Not applicable — paper does not address gut microbiome effects of Ni exposure.