Ghasemidehkordi et al. 2018 — Pb and tHg in ten green leafy vegetables and herbs from Markazi province, Iran, with soil/water context and adult non-carcinogenic risk assessment

This Iranian cross-sectional field survey quantifies total Pb and total Hg in ten species of green leafy vegetables and herbs, agricultural soil (0–15 cm), and irrigation water from five agricultural sites across Markazi province (an industrial-agricultural region of northwest Iran with aluminum, steel, petroleum, and automotive industries). Samples collected May–August 2014; analysis by ICP-OES (Varian Vista-MPX, Spectroacros EOP, with ultrasonic nebulizer). All vegetable Pb means exceeded the WHO/FAO 300 µg/kg leafy-vegetable Pb ceiling cited by the authors (range 990–1734 µg/kg dry weight across species). Hg means ranged 36–56 µg/kg dry weight; four species (Allium wakegi, Artemisia dracunculus, Lepidium sativum, Trigonella foenum-graecum) exceeded the 50 µg/kg drinking-water Hg “safety limit” the authors invoked. Soil and water Pb and Hg also exceeded WHO/FAO guidelines cited by the authors. Hazard Index (Pb + tHg THQ) for the combined 15–64 adult age range was 8.49 (urban) and 9.01 (rural); Pb contributed ~93 % and tHg ~7 % of HI; the authors concluded both urban and rural consumers face significant non-carcinogenic health risk from green leafy vegetable and herb consumption in this province.

Key numbers

Method validation (§3.1, Tables 1–2)

• Linear range Pb and Hg: 2.5–1000 µg/kg, with regression coefficients 0.9975 (Pb) and 0.9992 (Hg).
• Detection limits (LOD): Pb 2 µg/kg, Hg 0.35 µg/kg. Limits of quantification (LOQ): Pb 1.16 µg/kg, Hg 6.6 µg/kg. (See Verification notes for the LOD/LOQ swap and an LOQ-below-LOD inconsistency for Pb in the printed Table 2.)
• Recoveries (n=18 each, 6 spiking levels 15–750 µg/mL): Pb 96.2 % (soil), 106.8 % (vegetable), 113.5 % (water); Hg 98.2 % (soil), 104.3 % (vegetable), 115.1 % (water). RSD range 4.3–16.85 % across all matrices and analytes.

Table 3 — Mean Pb and Hg in vegetables (µg/kg dry weight), soil (µg/kg dry weight), and irrigation water (µg/L)

Across-vegetable pooled means (§3.2 text): Pb 1095 ± 722.07 µg/kg dw (range 990–1734); tHg 47.30 ± 23.35 µg/kg dw (range 36.12–56.14).

Standard limits cited by the authors: WHO/FAO leafy-vegetable Pb ceiling 300 µg/kg (Yahaya 2013); Hg “established safety limit” 50 µg/kg (Fawell et al. 2005 — note: the Fawell et al. reference is the WHO Mercury in Drinking-Water background document; the 50 µg/kg figure is a drinking-water-context value the authors apply to vegetables, with no explicit justification for the cross-matrix transfer). WHO irrigation-water Pb ceiling 0.01 mg/L = 10 µg/L cited at §3.2 (WHO 2007). All vegetable Pb means and the soil Pb mean exceed cited limits; the soil Hg mean is just above the 50 µg/kg threshold; the water Pb mean (494 µg/L) exceeds the 10 µg/L irrigation guideline by ~49-fold.

Table 4 — THQ for Pb and tHg and Hazard Index (HI) by age group, urban vs. rural Markazi consumers

THQ < 1 = no significant non-carcinogenic risk; THQ ≥ 1 = possible adverse effects; HI ≥ 10 = considerable non-carcinogenic risk (Lei et al. 2015 thresholds, §2.11.3). All Pb THQ values exceed 1; all Hg THQ values are below 1; all HI values exceed 1 (range 7.92–9.76). The authors state Pb is “14 times more than Hg” in HI contribution; from Fig. 3 caption: Pb accounts for 93 % and Hg for 7 % of HI.

Risk-assessment parameter set (§2.11.2)

• THQ formula (as printed, §2.11.2 Eq. 2): THQ = (EF × ED × FIR × C / RFD × WAB × TA) × 10⁻³. See Verification notes — the printed formula contains a typographic bracket-omission inconsistent with the standard USEPA THQ definition; the values in Table 4 are reconstructible with the standard interpretation THQ = (EF × ED × FIR × C) / (RFD × WAB × TA × 10⁶) where C is in µg/kg and RFD is in mg/kg/day.
• EF (exposure frequency): 365 days/year.
• ED (exposure duration): 70 years.
• TA (averaging time): 70 years (= 70 × 365 days).
• FIR (per-capita vegetable consumption): 250 kg/person/year = 684 g/person/day (FAO 2015 Iran figure).
• RFD: Pb 0.0004 mg/kg/day; Hg 0.0003 mg/kg/day (USEPA 2000).
• C: concentration of Pb or Hg in vegetable (µg/kg dry weight, as printed in Table 3).
• WAB (body weight): urban 64/71/74/74/72/69 kg for 15–24/25–34/35–44/45–54/55–64/15–64; rural 60/66/69/68/67/65 kg for the same age groups (Asgari et al. 2009 surveillance values).

Transfer factor (TF) interpretation (§3.2)

• All Pb TFs are below 1 (range 0.19–0.34): vegetables and herbs are weak Pb accumulators from this contaminated soil, with Spinacia oleracea the highest (0.34).
• Four Hg TFs exceed or approach 1: Allium wakegi 1.05, Artemisia dracunculus 1.07, Lepidium sativum 1.04, Trigonella foenum-graecum 1.02; the authors note this likely reflects atmospheric Hg deposition rather than soil-root uptake (Cao et al. 2010).
• The authors conclude the rank order of HI across age groups in both urban and rural Markazi areas is 15–24 > 25–34 > 55–64 > 45–54 > 35–44 (Conclusions §4); the youngest adult cohort carries the highest risk, driven primarily by Pb intake relative to body weight.

Methods (brief)

Study design. Cross-sectional vegetable, soil, and water survey across five agricultural sites in Markazi province, Iran (34° 05′ 30.26″ N, 49° 41′ 20.98″ E), May–August 2014. Ten leafy-vegetable/herb species collected per site (~1 kg each); 100 total vegetable composites (10 species × 10 samples). Five sites × six sample plots = 30 soil samples. 30 irrigation-water samples (in triplicate). Total n=160 sample units across the three matrices.

Vegetable/herb preparation. Samples washed with tap water, rinsed twice with deionized water, oven-dried 60–70 °C for 24 h, ground to small particle size, stored in polyethylene bags for ≤6–12 months prior to digestion. ~1 g powder + 15 mL acid mixture HNO₃ (70 %) + H₂SO₄ (65 %) + HClO₄ (70 %) in 5:1:1 v/v ratio in test tubes (Shakya & Khwaounjoo 2013 method).

Soil preparation. 10–15 cm depth samples, oven-dried 60–70 °C for 12–24 h, powdered. Digestion with 6 mol/L HNO₃; filtered under vacuum through Whatman No. 42 paper.

Water preparation. Collected from agricultural site irrigation in pre-cleaned polyethylene bottles (10 % HNO₃ soak overnight, two rinses with deionized water; Chary et al. 2008 protocol). Direct ICP-OES injection.

Instrumentation. ICP-OES EOP, Spectroacros, Varian Vista-MPX (Germany); ultrasonic nebulizer; argon carrier (99.999 % purity grade 5; 0.7 L/min for modified Lichte nebulizer, 13 L/min coolant); 4-channel peristaltic pump at 60 rpm pre-flush (45 s) and 30 rpm analysis; power 1400 kW (Marin et al. 2011 protocol).

Calibration. Stock solutions 10 µg/mL Merck; spiked calibration standards at 2.5–1000 µg/L equivalent in blank vegetable, soil, and water matrices. Recovery determined at six spiking levels (15, 25, 75, 150, 250, 500, 750 µg/mL — note: this is seven levels as listed, but the table reports six; the discrepancy is a paper-internal inconsistency).

Speciation. ICP-OES measures total elemental Pb and total elemental Hg. No methyl-/inorganic-Hg fractionation; no Pb species partitioning. Frontmatter metals: reflects total-Pb and total-Hg ([Pb, tHg]); MeHg is not reported.

Statistics. Means, SDs, min/max via SPSS v.22; one-way ANOVA; p-value threshold 0.05; data reported as normal-distributed enabling parametric tests. Figures generated in Excel 2016.

Risk-assessment formulas. THQ per Chien et al. 2002 (Eq. 2, with the bracket-typography caveat); HI = THQ_Pb + THQ_Hg per Fakhri et al. 2017–2018 (Eq. 3). Thresholds per Lei et al. 2015: THQ ≥ 1 = possible adverse effects; HI ≥ 10 = considerable risk.

Implications

This source contributes Iranian field-survey occurrence data for total Pb and total Hg in ten species of green leafy vegetables and herbs, agricultural soil, and irrigation water across one industrial-agricultural province (Markazi). Its principal contributions to the wiki evidence pool:

• Bulk leafy-vegetable and herb Pb occurrence (µg/kg dw) in a heavily industrialized Iranian province: range 990 (A. ampeloprasum) to 1734 (S. oleracea) across species means; soil Pb 4994 µg/kg dw; irrigation water Pb 494 µg/L. All vegetable Pb means exceed the 300 µg/kg WHO/FAO leafy-vegetable Pb ceiling cited by the authors; the water Pb mean exceeds the 10 µg/L irrigation guideline by ~49-fold. Useful as upper-end pooling data for Iranian-industrial-context leafy-vegetable Pb occurrence.
• Bulk leafy-vegetable and herb tHg occurrence (µg/kg dw): range 36 (S. oleracea) to 56 (A. dracunculus) across species means; soil tHg 52 µg/kg dw; irrigation water tHg 67 µg/L. Four of ten species exceed the 50 µg/kg threshold the authors invoke; the rest fall below. Useful as low-to-moderate-end occurrence data for a non-fish vegetable matrix in an industrial setting.
• Pathway evidence. Soil-to-plant TF for Pb is uniformly <1 (0.19–0.34) while TF for Hg is >1 for four species (1.02–1.07), suggesting that for these vegetables in this region, Pb accumulation is limited by root barriers despite high soil burden while Hg uptake may be supplemented by atmospheric deposition onto leaf surfaces (Cao et al. 2010). The paper does not measure atmospheric Hg directly, so the deposition pathway remains inferential.
• Risk-assessment parameter set. Documents a complete Iranian-context THQ/HI parameterization (Asgari et al. 2009 urban/rural body-weight surveillance values across five 10-year age cohorts; FAO 2015 250 kg/person/year vegetable consumption; USEPA 2000 RfDs). The 684 g/day FIR is a high-end staple-vegetable consumption value typical of Iranian dietary surveys and is not directly transferable to settings where leafy vegetables and herbs are non-staple commodities.
• Speciation limitation. Total Pb and total Hg only; no MeHg analysis. The 50 µg/kg Hg threshold the authors apply is a drinking-water-context value (WHO 2007 via Fawell et al. 2005), not a vegetable-matrix regulatory ceiling; the cross-matrix transfer should not be treated as a regulatory exceedance for downstream synthesis. Frontmatter metals: reflects this ([Pb, tHg]).

Sample size is moderate (n=100 vegetable composites across 10 species × 5 sites × 2 replicate samples per site; n=30 each for soil and water). The single-province sampling footprint, single-year window (May–August 2014), and absence of certified-reference-material validation limit standalone authority; the paper supports B-tier generalization to Iranian-industrial leafy-vegetable Pb burden but not to non-industrial Iranian agriculture or to other commodity classes. The 1.07 Hg TF in Artemisia dracunculus is notable but the underlying mechanism (foliar deposition vs. true root uptake) is not isolated by the study design.

Wiki pages this source may touch

• lead
• mercury-total
• mercury
• spinach
• parsley
• leafy-vegetables
• vegetables
• fresh-herbs
• herbs-and-spices
• water
• leafy-vegetables-other
• spinach

Verification notes

• Frontmatter discipline. All ingredient, product, and metal slugs verified against the 2026-05-18 taxonomy snapshot. Of the ten vegetable/herb species reported, only spinach (S. oleracea) and parsley (P. crispum) have dedicated ingredient pages in the current taxonomy. The other eight (leek, Welsh onion, tarragon, coriander, garden cress, mint, radish leaves, fenugreek) do not have dedicated slugs and are not auto-stubbed by this ingest per the freq-1-per-paper rule; they fan to leafy-vegetables, fresh-herbs, and herbs-and-spices umbrellas. water is included because the paper provides direct irrigation-water Pb and tHg measurements (493 µg/L Pb, 67 µg/L Hg). For products, leafy-vegetables-other and spinach are the two locked-taxonomy slugs that match the matrix; herb-specific product pages do not exist in the current taxonomy snapshot.
• Cite-key choice. ghasemidehkordi2018-markazi-vegetables-pb-hg follows the descriptive-suffix convention (first author, year, region, commodity, analytes). DOI 10.1016/j.fct.2018.01.048 is the canonical identity.
• Evidence tier B. Peer-reviewed in Food and Chemical Toxicology (Elsevier, subscription) by an experienced Iranian heavy-metals analytical team (Rezaei/Khaneghah/Fakhri co-authorships across multiple Iranian food-survey papers in the wiki corpus). ICP-OES on a current-generation Varian/Spectro instrument with ultrasonic nebulizer (notably improves Hg sensitivity). No certified reference material reported, no inter-laboratory comparison, no isotope-dilution validation. The recovery range 96.2–115.1 % is acceptable but the RSD upper bound (16.85 % for Pb in soil) is wide for an A-tier classification. Tier B (not A) because of the single-province sampling, single-year window, modest sample size per species (n=10), no CRM, and several paper-internal table/text inconsistencies flagged below.
• License. Elsevier subscription (the FCT publication does not bear a CC license; the access route is via institutional subscription or paywall).
• Speciation. Total Pb and total Hg only via ICP-OES. No MeHg/iHg fractionation. The wiki frontmatter metals: field uses [Pb, tHg] per CLAUDE.md Part 14; the body uses “tHg” in the data tables and “Hg” only where the authors’ own framing requires it (formulas, paper-internal nomenclature).
• Basis. Vegetable values in Table 3 are reported on a dry-weight basis (samples oven-dried at 60–70 °C for 24 h prior to digestion; §2.3); the table column header is implicit but §3.2 narrative confirms “dw”. Soil values are dry-soil basis (standard). Water values are µg/L. The THQ formula (§2.11.2) applies the dry-weight C value × 250 kg/year × 684 g/day FIR without an explicit fresh-to-dry conversion, which yields a likely conservative overestimate of THQ if Iranian consumers eat these leafy vegetables and herbs predominantly fresh (typical water content 80–90 % for these species). The wiki page records the dry-weight basis as printed; downstream synthesis should apply a fresh-weight correction (factor ~0.10–0.20) before pooling with fresh-weight datasets from other studies.
• Brand firewall (Part 12). No branded products are measured or reported. The methods name analytical-instrument vendors (Varian Vista-MPX, Spectroacros; Whatman filter paper; Merck chemicals; SPSS v.22) and statistical software, all of which fall under the 2026-05-17 scientific-method-vendor exception. Sites are identified by Iranian province name only (Markazi), with no farm or producer brand identification.
• Wiki/HMTc firewall (Part 2). No threshold proposals, no consumer advisories, no synthesis claims against other Iranian vegetable papers. The Implications section reports what this paper contributes to the pool; cross-paper synthesis is the Part 9 workflow’s job. The 50 µg/kg Hg “safety limit” the authors apply is a drinking-water-context value (WHO 2007 via Fawell et al. 2005) and is not a vegetable-matrix regulatory ceiling; the wiki records the authors’ framing without endorsing the cross-matrix transfer.
• Paper-internal inconsistencies flagged for downstream synthesis caution:
  • Abstract analyte-vegetable association reversed. The Abstract states: “Artemisia dracunculus L with 56.147 ± 17.30 µg/kg and Spinacia oleracea L with 1733.62 ± 2264.7 µg/kg can uptake and accumulate more concentration of Pb and Hg in their tissues, respectively.” The “Pb and Hg, respectively” parallel structure maps Artemisia→Pb and Spinacia→Hg, but Table 3 (and §3.2 narrative) make clear the opposite: Artemisia (56.15 µg/kg) is the highest Hg species and Spinacia (1733.62 µg/kg) is the highest Pb species. The Abstract has the analytes swapped relative to the species accumulating them. Table 3 is the authoritative reading; reproduced here as printed. This is a writing/copy-edit error that does not affect the underlying numerical data.
  • §3.2 soil Pb mean missing a digit. The §3.2 text states soil Pb mean as “499.83 ± 1287.8 µg/kg” but Table 3 and the Abstract both give 4993.83 (or 4993.84) ± 1287.88. The Table 3 / Abstract value is correct; §3.2 dropped a digit in typesetting. Reproduced verbatim where Table 3 controls.
  • §3.2 S. oleracea Pb SD typographic error. §3.2 reports S. oleracea Pb as “1733.62 ± 226.4” but Table 3 (and Abstract) give SD 2264.74. The Table 3 value is correct; §3.2 transposed digits. Reproduced from Table 3.
  • §3.2 numeric range error for Hg. §3.2 narrative: “The level of Hg accumulation in samples was between 56.14 ± 17.3 to 36.12 ± 20.44 µg/kg dw” — the narrative orders these as a range from max to min (56.14 max in Artemisia → 36.12 min in Spinacia), correctly identifying the endpoints, but the second-named species (“more and less concentration of Hg among other green leafy”) is then assigned “Artemisia dracun-culus L and Spinacia oleracea L can accumulate more and less concentration of Hg.” This intra-paragraph reading is consistent with Table 3 (Artemisia high, Spinacia low) — the only inconsistency is with the Abstract’s reversed analyte mapping (above).
  • THQ formula typographic bracket omission. §2.11.2 Eq. 2 prints: THQ = (EF × ED × FIR × C / RFD × WAB × TA) × 10⁻³. The standard USEPA THQ has brackets grouping numerator and denominator separately: THQ = (EF × ED × FIR × C) / (RFD × WAB × TA) × 10⁻³ (or 10⁻⁶ for µg/kg-to-mg/kg unit conversion). The Table 4 values are consistent with the standard interpretation; the printed equation is a typographic omission. Reproduced as printed, with the standard interpretation noted.
  • §3.2 “Pb concentration in vegetables…in this study was higher than the standard limit set by WHO/FAO for Pb (300 µg kg⁻¹) (Yahaya, 2013).” This sentence cites Yahaya (2013) for the 300 µg/kg WHO/FAO leafy-vegetable Pb limit. Yahaya 2013 (Afr. J. Pure Appl. Chem. 7:179–183) is a Nigerian vegetable survey, not the WHO/FAO Codex itself; the authors are citing the limit secondhand. The wiki page records the authors’ cited value (300 µg/kg) without endorsing the attribution chain.
  • Spiking-level list mismatch. §2.10 lists “concentration levels of 15, 25, 75, 150, 250, 500 and 750 µg/mL” (seven values) but the Table 2 RSD range and “n = 6” header indicate six levels were actually used. The discrepancy is unresolved in the paper; reproduced from §2.10 verbatim with note.
  • §3.1.2 LOD/LOQ swap. Text states “The LOQs for the Hg and Pb were calculated as 6.6 and 1.16 µg/kg, respectively. The detection limits for Pb and Hg were 2 and 0.35 µg/kg, respectively.” The numerical ordering implies Pb LOD 2, Hg LOD 0.35 (consistent with Table 2’s LOD column 2 / 0.35) and Hg LOQ 6.6, Pb LOQ 1.16. But the printed Pb LOQ of 1.16 µg/kg is below the Pb LOD of 2 µg/kg — an analytical-logic contradiction (LOQ is normally ~3× LOD). Reproduced as printed; downstream synthesis should treat the Pb LOD = 2 µg/kg as the operative reporting threshold and discount the Pb LOQ value.
  • No correction has been applied to any of the above; values are recorded exactly as printed in the authoritative source location (Table 3 for occurrence; Table 4 for risk metrics). Synthesis passes consuming this source should weight the Abstract’s analyte-species mapping with appropriate skepticism and rely on Table 3 for occurrence pooling.
• Sampling year. May–August 2014 stated explicitly (§2.3). Manuscript received 28 November 2017, revised 11 January 2018, accepted 27 January 2018, online 31 January 2018.
• Data integrity. All 22 vegetable/soil/water rows in Table 3 (Pb panel and Hg panel), all 36 cells in Table 4 (urban + rural × 6 age groups × 3 metrics), Table 1 (linear equations), Table 2 (recovery and RSD), and all parameter values in §2.11.2 transcribed from the source PDF and verified against the rendered tables. The seven paper-internal inconsistencies above are flagged in this section; no other transcription discrepancies identified.
• Audit subagent (2026-06-01) flagged [[ingredients/leafy-vegetables]] as not in the taxonomy snapshot; verified against source — finding was a false positive because the 2026-05-18 taxonomy snapshot (docs/gpt-collaboration/taxonomy-snapshot.md) contains both leafy-greens and leafy-vegetables in its ingredient slug list (line 40: “…leafy-greens,leafy-vegetables,legumes…”), and both wiki/ingredients/leafy-greens.md and wiki/ingredients/leafy-vegetables.md exist as canonical pages. The slug is valid; no change required. All other audit checks (numerical fidelity, speciation/methods, brand firewall, wiki/HMTc firewall) passed.
• Audit subagent (2026-06-01) flagged the across-vegetable pooled means (Pb 1095 ± 722.07 µg/kg; tHg 47.30 ± 23.35 µg/kg from §3.2 narrative) as a completeness gap; verified against source — values added to the Key numbers section under Table 3 as an “across-vegetable pooled means” line. This is a useful cross-paper-synthesis input that complements the per-species means.

Page history

The five most recent substantive edits to this page. The full version history lives in git; when DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.