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Contamination of Heavy Metal(Loid)S in Cereals, Vegetables, and Legumes Purchased from Local Markets of Jiaozuo, China and The Associated Health Risk Assessment

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Overview

This single-author Henan Polytechnic University study measured eight elements (Pb, cadmium (Cd), total arsenic (As), total mercury (Hg), chromium (Cr), nickel (Ni), Cu, Zn) in 244 commercially available cereal, legume, and vegetable samples purchased in 2024 from Jiaozuo City markets (Henan Province, central China) and applied the USEPA target hazard quotient (THQ) and target carcinogenic risk (TCR) framework to estimate non-carcinogenic and carcinogenic risks for adult and child consumers. Pollution-index analysis ranked food categories legumes > cereals > leafy greens > kale > solanaceous fruits > edible mushrooms > tubers, with Hg in rice (mean 0.124 mg/kg; 44.16% of cereal samples exceeding the GB 2762-2022 Hg limit) and Ni in peanuts (75.47% exceedance) as the dominant single-element exceedances. Children’s TTHQ for the combined cereal-legume-vegetable diet reached 4.619 (adults 2.518), with rice (TTHQ 5.481, children) and peanuts (TTHQ 2.035, children) contributing most. Cumulative carcinogenic risk remained within the USEPA acceptable range (children 8.92×10⁻⁶; adults 2.65×10⁻⁶). The study uses single-laboratory sampling, single-composite measurement per product without disclosed analytical replicate counts, fresh-weight basis, and the GB 2762-2022 (China) regulatory baseline.

Key numbers

Cereal samples (n=78; rice 39, wheat flour 27, corn 12; Table 7, page 188; mg/kg fresh weight):

  • Cr range nd–1.500 mg/kg, mean 0.210 ± 0.255 mg/kg; exceedance rate 2.60% vs GB 2762-2022 cereals limit 1.0 mg/kg.
  • As range 0.01–0.170 mg/kg, mean 0.043 ± 0.065 mg/kg; within standard (paddy/rice limit 0.2 mg/kg; cereals-except-paddy 0.1 mg/kg).
  • Cd range 0.010–0.040 mg/kg, mean 0.011 ± 0.012 mg/kg; within standard (rice 0.2 mg/kg; cereals-except-paddy 0.1 mg/kg).
  • lead (Pb) range 0.010–1.15 mg/kg, mean 0.124 ± 0.142 mg/kg; exceedance 3.90% vs cereals limit 0.2 mg/kg.
  • Hg range 0.002–0.444 mg/kg, mean 0.044 ± 0.088 mg/kg; exceedance 44.16% vs cereals limit 0.02 mg/kg. Rice Hg mean implied ~0.345 mg/kg from Table 8 THQ back-calculation (C = THQ × BW × RfD / IR = 3.983 × 15.9 kg × 3.00E-04 / 0.055 kg/d = 0.345 mg/kg, using child rice Hg THQ 3.983, RfD_Hg 3.00E-04, child BW 15.9 kg, IR_cereal 55 g/d). This is consistent with Figure 1 (page 189) rice Hg boxplot showing max approaching 0.450 mg/kg and median near 0.10 mg/kg.
  • Ni range nd–0.700 mg/kg, mean 0.164 ± 0.126 mg/kg; exceedance 3.90% vs cereals limit 0.4 mg/kg.
  • Cu range 0.180–6.990 mg/kg, mean 1.608 ± 1.087 mg/kg; within standard.
  • Zn range 0.460–15.500 mg/kg, mean 7.577 ± 3.789 mg/kg; within standard.

Vegetable samples (n=114; Table 7, page 188; mg/kg fresh weight):

  • Cr range 0.003–0.278 mg/kg, mean 0.032 ± 0.054 mg/kg; within standard (fresh vegetables 0.5 mg/kg).
  • As range nd–0.107 mg/kg, mean 0.006 ± 0.006 mg/kg; within standard (fresh vegetables 0.5 mg/kg).
  • Cd range 0.000–0.104 mg/kg, mean 0.008 ± 0.017 mg/kg; within standard (fresh vegetables 0.05 mg/kg; leafy 0.2 mg/kg; root/tuber 0.1 mg/kg).
  • Pb range up to 0.430 mg/kg (body text page 186 states “0.430 mg/kg for Pb” as the upper end of the vegetable Pb range), mean 0.013 ± 0.028 mg/kg; spinach showed the highest median among leaf greens (boxplot Figure 1, page 190, indicates spinach Pb median approximately 0.05 mg/kg with maximum approaching 0.08 mg/kg); the 0.430 mg/kg maximum exceeds the GB 2762-2022 leafy/Brassica vegetable limit of 0.3 mg/kg in at least one sample, yet the paper’s conclusion (page 199) states vegetable Pb remained “below the corresponding standard limits” — a paper-internal inconsistency flagged below.
  • Hg range 0.000–0.014 mg/kg, mean 0.004 ± 0.003 mg/kg; exceedance 0.90% vs fresh vegetables limit 0.01 mg/kg.
  • Ni range 0.002–0.086 mg/kg, mean 0.016 ± 0.024 mg/kg; within standard (vegetables 0.3 mg/kg per Yang et al. 2018).
  • Cu range 0.002–0.599 mg/kg, mean 0.064 ± 0.096 mg/kg; within standard.
  • Zn range nd–3.991 mg/kg, mean 0.589 ± 0.570 mg/kg; exceedance 17.12% vs vegetables limit 1.0 mg/kg (FAO/WHO 2001).

Legume samples (n=52; soybean 21, peanut 21, mung bean 10; Table 7, page 188; mg/kg fresh weight):

  • Cr range 0.007–2.600 mg/kg, mean 0.717 ± 0.476 mg/kg; exceedance 16.98% vs legumes limit 1.0 mg/kg; soybean mean 1.143 mg/kg (exceedance 42.86% within soybean subset).
  • As range 0.001–0.003 mg/kg, mean 0.011 ± 0.009 mg/kg; GB 2762-2022 does not specify a total arsenic (tAs) limit for legumes (the paper notes this).
  • Cd range 0.01–0.430 mg/kg, mean 0.081 ± 0.128 mg/kg; within standard (legumes 0.2 mg/kg; peanut 0.5 mg/kg).
  • Pb range 0.002–0.072 mg/kg (body page 186), mean 0.086 ± 0.072 mg/kg (Table 7 page 188 and body page 188); the printed mean 0.086 exceeds the printed range maximum 0.072 — a paper-internal arithmetic inconsistency flagged below. Exceedance 13.21% vs legumes limit 0.2 mg/kg.
  • Hg range as printed in Table 7 (page 188) “0.15–24.22 × 10⁻³” mg/kg (i.e., 0.00015–0.02422 mg/kg); body page 188 states legume Hg mean 0.012 mg/kg (SD not separately stated). Body page 186 lists the legume Hg range as “0.500–20.100 mg/kg” which is three orders of magnitude larger than Table 7 and appears to be a misprint or transcription of Cu/Ni values — flagged below. GB 2762-2022 does not specify a total mercury (tHg) limit for legumes.
  • Ni mean 7.914 ± 5.378 mg/kg (Table 7 and body page 188); body page 186 lists legume Ni range “6.860–12.400 mg/kg” — the printed mean 7.914 sits within this range but the table-vs-body cross-substitution noted above complicates which numbers belong to Ni vs Cu. Exceedance 75.47% vs legumes limit 3.0 mg/kg per Yang et al. 2018.
  • Cu mean 7.297 ± 1.280 mg/kg per Table 7 page 188; body page 188 prints legume Cu mean as 9.297 mg/kg — a 2 mg/kg disagreement between Table 7 and body text flagged below. Body page 186 does not list a separate Cu range for legumes.
  • Zn range 20.100–33.100 mg/kg, mean 25.988 ± 3.160 mg/kg.

Single-factor and Nemerow’s pollution-index findings (Figure 2, page 191):

  • As, Cd, Cu, Zn within safe limits across all categories.
  • Cr in peanuts and Hg in spinach, Chinese cabbage, pak choi at precautionary level (0.7 < Pi ≤ 1).
  • Cr in soybeans, Pb in corn, Hg in corn, Ni in mung beans at slight pollution (1 < Pi ≤ 2).
  • Ni in peanuts at moderate pollution (2 < Pi ≤ 3).
  • Hg in rice and Ni in peanuts at severe pollution (Pi > 3).
  • Nemerow’s synthetic pollution index (Figure 2(a), page 191) reports per-food values including peanut 1.464, rice 1.184, mung bean 1.114, corn 0.846, Chinese chives 0.658, Chinese cabbage 0.541, pak choi 0.541, spinach 0.541, with the food categories ordered from most-polluted to least-polluted per the body-text summary (page 191): legumes > cereals > leafy greens > kale > solanaceous fruits > edible mushrooms > tubers. Corn, soybeans, and mung beans classified slightly polluted; peanuts moderately polluted; rice severely polluted; remaining items safe.

Non-carcinogenic risk — children (Table 8, page 193; THQ; BW 15.9 kg, IR_cereal 55 g/d, IR_vegetable 100 g/d, IR_legume 25 g/d):

  • Cereals TTHQ: rice 5.481 (Hg THQ 3.983 = 72.7% of rice TTHQ), corn 2.060, wheat 0.853. Cereal sum TTHQ 8.394.
  • Legumes TTHQ: peanut 2.035 (Ni THQ 0.791 dominant), soybean 1.741, mung bean 0.949.
  • Vegetables TTHQ: edible mushrooms 0.554 (mean), leafy vegetables 0.333, kale 0.132, tubers 0.111, solanaceous fruits 0.104. All vegetable categories THQ <1. Spinach TTHQ 0.505; pak choi 0.404; Chinese cabbage 0.342.
  • Table 8 grand-total TTHQ row 18.031 (sum of every per-food TTHQ in the table).

Non-carcinogenic risk — adults (Table 9, page 194; THQ; BW 56.8 kg, IR_cereal 300 g/d, IR_vegetable 400 g/d, IR_legume 30 g/d):

  • Cereals TTHQ: rice 2.704 (Hg THQ 1.673 dominant), wheat 1.213, corn 1.117.
  • Legumes TTHQ: peanut 0.667, soybean 0.617, mung bean 0.351 (all <1).
  • Vegetables TTHQ: edible mushrooms 0.672, leafy greens 0.384, kale 0.153, tubers 0.140, solanaceous fruits 0.123 (all <1).
  • Table 9 grand-total TTHQ row 12.506.

Carcinogenic risk — children (Table 10, page 196; TCR; Cd, As, Cr only — Pb and Ni CSF rows are listed in Table 6 but TCR for Pb and Ni is not tabulated in Table 10):

  • Cereals TCR: wheat 8.65×10⁻⁷ > rice 6.98×10⁻⁷ > corn 2.42×10⁻⁷.
  • Vegetables TCR: edible mushrooms 6.63×10⁻⁶ > leafy greens 4.64×10⁻⁶ > tubers 1.04×10⁻⁶ > solanaceous fruits 7.43×10⁻⁷ > kale 7.34×10⁻⁷.
  • Legumes TCR: peanut 1.55×10⁻⁶ > soybean 1.13×10⁻⁶ > mung bean 2.56×10⁻⁷.
  • Table 10 grand-total TCR row 1.85×10⁻⁵.

Carcinogenic risk — adults (Table 11, page 197; TCR):

  • Cereals TCR: rice 2.03×10⁻⁶ > wheat 1.96×10⁻⁶ > corn 3.69×10⁻⁷.
  • Vegetables TCR: edible mushrooms 1.98×10⁻⁶ (verified against Table 11 row means: needle 7.46×10⁻⁷, oyster 2.15×10⁻⁶, mushroom 3.03×10⁻⁶, average ≈ 1.97×10⁻⁶) > leafy greens 6.80×10⁻⁶ as printed in body text page 195; however Table 11 leafy-greens row sums (spinach 1.09×10⁻⁶, Chinese chives 2.60×10⁻⁷, Chinese cabbage 5.90×10⁻⁷, romaine 6.89×10⁻⁷, pak choi 1.08×10⁻⁶, lettuce 3.75×10⁻⁷) average ≈ 6.81×10⁻⁷, suggesting the body-text “6.80×10⁻⁶” is a misprint that should read “6.80×10⁻⁷” — flagged below. Tubers 2.32×10⁻⁷ > kale 6.38×10⁻⁷ > solanaceous fruits 6.60×10⁻⁷.
  • Legumes TCR: peanut 1.10×10⁻⁶ > soybean 4.26×10⁻⁷ > mung bean 9.34×10⁻⁸.
  • Table 11 grand-total TCR row 1.82×10⁻⁵.

Cumulative diet-wide risk (Table 12, page 199):

  • TTHQ — children: vegetables 0.246, cereals 2.798, legumes 1.575, cumulative 4.619 (>1, indicating non-carcinogenic risk).
  • TTHQ — adults: vegetables 0.292, cereals 1.678, legumes 0.545, cumulative 2.518 (>1).
  • TCR — children: vegetables 7.34×10⁻⁶, cereals 6.02×10⁻⁷, legumes 9.77×10⁻⁷, cumulative 8.92×10⁻⁶ (<1×10⁻⁴, acceptable).
  • TCR — adults: vegetables 6.53×10⁻⁷, cereals 1.46×10⁻⁶, legumes 5.39×10⁻⁷, cumulative 2.65×10⁻⁶ (<1×10⁻⁴, acceptable).

Reference regulatory limits cited (Table 4, page 184):

  • GB 2762-2022 (National Health Commission of the People’s Republic of China, State Administration for Market Regulation 2022): Hg cereals ≤0.02 mg/kg, Hg fresh vegetables ≤0.01 mg/kg, Hg edible mushrooms ≤0.1 mg/kg; Pb cereals ≤0.2 mg/kg, Pb vegetables-except-Brassica-leafy-leguminous-potatoes ≤0.1 mg/kg, Pb Brassica/leafy ≤0.3 mg/kg, Pb yams ≤0.2 mg/kg, Pb edible mushrooms ≤0.5 mg/kg (oyster ≤0.3 mg/kg), Pb legumes ≤0.2 mg/kg; tAs vegetables ≤0.5 mg/kg, tAs edible mushrooms ≤0.5 mg/kg, tAs cereals-except-paddy ≤0.5 mg/kg, tAs rice ≤0.2 mg/kg; inorganic arsenic (iAs) cereals-except-paddy ≤0.1 mg/kg, iAs paddy/rice ≤0.2 mg/kg; Cd fresh vegetables ≤0.05 mg/kg, Cd leafy vegetables ≤0.2 mg/kg, Cd root/tuber/stem vegetables ≤0.1 mg/kg, Cd fresh edible mushrooms ≤0.2 mg/kg, Cd mushroom ≤0.5 mg/kg, Cd legumes ≤0.2 mg/kg, Cd peanut ≤0.5 mg/kg.
  • Ministry of Agriculture of the People’s Republic of China 2005: Cr cereals ≤1.0 mg/kg, Cr fresh vegetables ≤0.5 mg/kg, Cr legumes ≤1.0 mg/kg; Cu cereals/products ≤10 mg/kg, Cu beans/products ≤20 mg/kg; Zn cereals/products ≤50 mg/kg, Zn beans/products ≤100 mg/kg.
  • FAO/WHO 2001: Cu vegetables ≤20 mg/kg, Zn vegetables ≤1.0 mg/kg.
  • Yang et al. 2018: Ni cereals ≤0.4 mg/kg, Ni legumes ≤3.0 mg/kg, Ni vegetables ≤0.3 mg/kg.

Methods (brief)

Samples (n=244) collected from Jiefang District (Xinhua, Dazhang, Yonghui, Wangfujing, Little Snail supermarkets; Zhongzhou and Moon Season markets; Jiaobei Marketplace) and Shanyang District (Yutong Agricultural Trade, Lubao Wholesale, Pak Tai Ka Yuen, Tanan farmers, Baida supermarkets) within Jiaozuo City, Henan Province, central China. Sampling year not stated; publication year 2024.

Sample preparation: vegetable samples cleaned with deionised water, oven-dried at 70°C for 30 min then 105°C to constant weight; cereal and bean samples cleaned, dried at 105°C to constant weight. Dried samples ground and sieved through 100-mesh, stored in sealed plastic bags. For digestion, 300 mg (±0.001 g) sample weighed into 50 mL PTFE digestion jar; 8 mL concentrated HNO₃ for pre-dissolution, then 2 mL H₂O₂, sealed lid, microwave digestion ramped to 150°C in 10 min and held at 180°C for 20 min.

Instrumentation: Hg by Direct Mercury Analyzer (DMA-80, Milestone, Italy) — total Hg measurement, no speciation. Pb, Cd, Cr, As, Ni, Cu, Zn by inductively coupled plasma mass spectrometry (Varian 810-MS, Jena, Germany) — total elemental As, no speciation between iAs and organoarsenic. ICP-MS operating parameters (Table 2, page 183): 1450 W power, 18.0 L/min plasma flow, 1.80 L/min auxiliary gas, 0.85 L/min nebuliser, 0.85 L/min sheath, 2 rpm peristaltic pump, 6.5 mm sampling depth, 1.0 mm sampling cone aperture, 0.4 mm interception cone bore, mass-analysis mode, ⁷²Ge internal standard. Results reported on fresh-weight basis.

Quality control: each 24-sample batch accompanied by one standard reference material (Hunan rice GBW10045a) and one deionised-water blank; blanks below detection limit; parallel-sample relative standard deviation within ±20%. SRM measurements (Table 3, page 183) for As 0.10±0.01 mg/kg (reference 0.12±0.02), Cd 0.32±0.02 (reference 0.32), Cr 0.08±0.02 (reference 0.08), Cu 2.23±0.16 (reference 2.4±0.2), Hg 2.94±0.16 µg/kg (reference 3.5±0.8), Ni 0.244±0.04 (reference 0.27±0.03), Pb 0.06±0.02 (reference 0.08±0.02), Zn 10.63±0.42 (reference 12.4±1.2) — all within prescribed error limits.

Contamination assessment: single-factor pollution index Pi = Ci/Si and Nemerow synthetic index P = √[(P²_ave + P²_imax)/2], where Si are the GB 2762-2022, Ministry of Agriculture 2005, FAO/WHO 2001, or Yang et al. 2018 limits in Table 4. Five-grade contamination classification per Huang et al. 2018: ≤0.7 safe, 0.7–1 precaution, 1–2 slight, 2–3 moderate, >3 severe.

Health risk: USEPA model. Target hazard quotient THQ = EDI/RfD = (ED×EF×IR×C)/(BW×AT_n×RfD). Cumulative TTHQ = Σ THQ. Carcinogenic risk CR = (C×IR×CSF×ED)/(BW×AT_c). TCR = Σ CR. Adult parameters: BW 56.8 kg, ED 30 a, EF 365 d/a, IR_vegetable 400 g/d, IR_cereal 300 g/d, IR_legume 30 g/d. Child parameters: BW 15.9 kg, ED 10 a, IR_vegetable 100 g/d, IR_cereal 55 g/d, IR_legume 25 g/d. RfD values from US EPA 2015 / Xiao et al. 2017: Pb 4.00×10⁻³, Cr 3.00×10⁻³, Cd 1.00×10⁻³, As 5.00×10⁻², Ni 2.00×10⁻², Zn 3.00×10⁻¹, Cu 4.00×10⁻², Hg 3.00×10⁻⁴ mg/(kg·d). CSF values: Cd 6.1, As 1.5, Cr 5.00×10⁻¹, Pb 8.50×10⁻³, Ni 8.40×10⁻³ mg/(kg·d)⁻¹.

Key limitations: single-author single-laboratory study; sample collection year not stated; per-product within-market variance and replicate counts per analysis not disclosed; Hg measured as total Hg with no methyl- vs inorganic-Hg speciation, which limits health-risk interpretation since RfD_Hg (3.00×10⁻⁴) is the methylmercury RfD; As reported as total elemental As with no iAs/tAs speciation, although the paper applies the As CSF of 1.5 (which is the inorganic-As CSF), introducing potential bias in cancer-risk estimates; legume Pb mean (0.086 ± 0.072 mg/kg) printed in the body text exceeds the printed legume Pb maximum (0.072 mg/kg) in Table 7, an internal arithmetic inconsistency reproduced from the source; legume Hg and Cu ranges in Table 7 appear cross-substituted with the legume Ni range (legume Hg row printed as 0.500–20.100 mg/kg, which equals the legume Cu row printed elsewhere, while the legume Ni printed range 6.860–12.400 mg/kg appears more consistent with the legume Cu range); fresh-weight basis used uniformly without specifying water content per product type, which complicates cross-study comparison with dry-weight datasets.

Evidence Fitness

EF-2 — distributional anchor with caveats. Provides defensible category-level mean and range estimates for Pb, Cd, Cr, Ni, Cu, Zn in 244 commercially purchased Chinese cereal, legume, and vegetable samples from one prefecture (Jiaozuo, Henan) in 2024, suitable for cross-region comparison with other Chinese-market datasets and for product-page evidence on legumes-pulses-other, leafy-vegetables-other, root-tuber-vegetables, spinach, peanuts, and soy-products. The total-Hg and total-As measurements without speciation, the absence of disclosed analytical replicate counts per composite, the absence of sampling-year disclosure, and the multiple paper-internal arithmetic inconsistencies in Table 7 legume rows reduce confidence below EF-1. The USEPA THQ/TCR application is the conventional dietary-exposure framework but inherits the speciation gaps (using inorganic-As CSF and methyl-Hg RfD with total-As and total-Hg concentrations).

Implications

Not synthesised — single-paper source page.

Provenance notes

PDF was retrieved by the autonomous discover skill into the archived source file under the filename auto-leafy-vegetables-other-pb-product_2024_10-62051-10-62051-ijnres-v2n1-21.pdf. The “leafy-vegetables-other-pb” portion of the auto-handle reflects the discovery query that surfaced this paper; the actual content covers eight elements across cereals, legumes, and vegetables broadly, of which leafy-vegetables-Pb is one panel. License CC BY-NC 4.0 per Warwick Evans Publishing footer (page 1 footer Creative Commons mark); open access.

Single author Zhen Wu, affiliated School of Resources & Environment, Henan Polytechnic University, Jiaozuo 454000, China. International Journal of Natural Resources and Environmental Studies Volume 2 Number 1 (2024), ISSN 3006-2012 (print) / 3006-0834 (online). Publisher Warwick Evans Publishing.

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