See et al. 2025 — Heavy metals in leafy vegetables from Selangor wet market, Malaysia

This 2025 Malaysian market survey measured Al, Cd, Cr, Cu, Fe, and Pb in four commercially important leafy vegetables (cabbage, mustard, spinach, and pak choi) purchased from Pasar Borong Selangor, one of the largest wholesale wet markets in the Klang Valley region, using inductively coupled plasma–optical emission spectrometry (ICP-OES). Cd, Cr, Cu, and Pb were undetected in all samples (below detection limits of <0.004 mg/kg for Cd and Pb, <0.01 mg/kg for Cr and Cu). Al and Fe were detected at levels within FAO/WHO permissible limits, with spinach consistently showing the highest concentrations of both metals. Health-risk assessment via target hazard quotient (THQ) and hazard index (HI) found low non-carcinogenic risks for the adult population across all vegetables and metals; target cancer risk (TCR) values were not calculable because no carcinogenic metals were detected.

Key numbers

Table 1 — Heavy metal concentrations (mg/kg fresh weight, mean ± SD; n=3 per vegetable):

LODs: Cd and Pb <0.004 mg/kg; Cr and Cu <0.01 mg/kg. ND = not detected. All concentrations are fresh weight. Tukey HSD significance letters (superscripts in original) indicate Al and Fe means differ significantly (p < 0.05) across vegetables; full significance letters preserved in the source table.

Rank order for detected metals (mean concentration):

• Al: spinach (41.37) > mustard (28.97) > pak choi (25.69) > cabbage (11.12) mg/kg
• Fe: spinach (13.59) > cabbage (6.30) > pak choi (4.14) > mustard (4.12) mg/kg

Table 2 — Estimated Daily Intake (EDI, mg/day/kg body weight; 240 g/day consumption, 70 kg adult):

ᵃ Table 2 of the source prints the Al total EDI as “3.123 × 10⁻³” but the four-vegetable Al EDI sum is 3.123 × 10⁻² (verified by direct addition; this also matches the source’s reported Al GTHQ of 0.03123 since RfD(Al)=1 makes THQ=EDI numerically). Reproduced as 3.123 × 10⁻² above; see verification notes.

Table 3 — Target Hazard Quotient (THQ) and Hazard Index (HI), adult population:

RfD values (mg/kg/day) used by authors: Al 1, Cd 0.001, Cr 0.003, Cu 0.04, Fe 0.7, Pb 0.0035. Oral cancer slope factors (CSF₀, mg/kg/day) cited but not applied since carcinogenic metals (Cd, Cr, Cu, Pb) were ND: Cd 0.38, Cr 0.5, Cu 1.7, Pb 0.0085. All HI values for individual vegetables, and the cumulative HI = 0.04299, are well below 1, indicating low non-carcinogenic risk from these specific leafy vegetables for the adult Selangor wet-market consumer.

Methods (brief)

Sampling: Four vegetable types (cabbage Brassica oleracea subsp. capitata, mustard B. juncea, spinach Spinacia oleracea, pak choi B. rapa var. chinensis), ~350 g each, were randomly purchased once per week for three consecutive weeks (19 October, 26 October, 2 November 2022) from Pasar Borong Selangor wholesale wet market in Seri Kembangan, Selangor. Same vendor lots were used across the three weeks: Lot 167 (spinach and pak choi, n=3 each), Lot 183 (cabbage, n=3), Lot 207 (mustard, n=3).

Sample preparation: Bruised or rotten portions removed; edible parts washed under running water then three times with distilled water, dried with tissue paper, cut, with ~400 g placed in airtight polyethene bags and stored frozen until digestion.

Digestion: Microwave acid digestion (MARS 6 system, 180°C, 45 min) using 9 mL 10 M HNO₃ + 3 mL 10 M HCl on 0.5 g homogenized sample, with conditions adapted from Gebeyehu & Bayissa (2020). Digestate filtered through Whatman No. 42 and adjusted with 2% HNO₃ prior to analysis. Digestion and analysis triplicated.

Analysis: ICP-OES (Avio 550 Max, PerkinElmer) integrated with the High Throughput System (HTS) flow-injection sample introduction. Power 1,400 W; RF generator 40 MHz; argon nebulizer flow 0.73 L/min, auxiliary 0.8 L/min, plasma 13 L/min; peristaltic pump 2.5 mL/min through Tygon PVC tubing. Calibration r² ≥ 0.998 against 1,000 ppm stock standards.

Statistics: Minitab 21.1, 95% confidence; one-way ANOVA with Tukey HSD comparison across vegetables, plus Pearson correlation. Results reported as mean ± SD (mg/kg fresh weight).

Health-risk equations: EDI = (E_f × E_D × F_IR × C_M × C_f) / (BW × T_A) × 0.001 where E_f = 365 d/y, E_D = T_A = 65 y, F_IR = 240 g/person/d (WHO 2002 low-intake reference), C_f = 0.085 (fresh→dry conversion factor, Harmanescu et al. 2011), BW = 70 kg adult. THQ = EDI/RfD; HI = Σ THQ across metals; TCR = EDI × CSF₀.

Study limitations: Small sample size (n=3 per vegetable type, single wet market, 3-week collection window in October–November 2022); does not capture inter-seasonal or inter-source variation. Edible portions only and after thorough washing (surface contamination partially removed). Health-risk calculations restricted to a 70 kg adult population at 240 g/day intake; do not assess children, pregnancy, or other vulnerable populations. ICP-OES does not speciate As, Cr, or Hg (the paper does not measure As or Hg at all). Cd, Cr, Cu, and Pb were all reported as ND across all samples, so no occurrence values for those analytes are contributed to the corpus from this study — only LOD-bounded non-detection statements.

Implications

Certification: This study documents non-detection of Cd, Cr, Cu, and Pb in four commonly consumed leafy vegetables from a major Malaysian urban wholesale market (Pasar Borong Selangor) — a positive baseline finding for Klang Valley supply. However, the authors note that other Malaysian studies (Sulaiman et al. 2020 in Pahang; Aweng et al. 2020 in Kelantan) found As, Pb, Cd, and other metals in leafy vegetables from agricultural and rural areas at concerning levels, suggesting market origin matters significantly. Non-detection in this study does not generalise to all Malaysian leafy vegetable supply.

Courses: Illustrates that market-point surveillance of leafy vegetables in urbanised Malaysia can show lower Cd/Pb contamination than farm-gate or near-mining surveys; the authors note that Pasar Borong Selangor draws supply both from within Selangor and from Cameron Highlands, Pahang (without concluding that the latter explains the non-detections). Al is the notable exception — spinach accumulates Al at 41.37 mg/kg, and the paper cites Martín-León et al. (2023) as having found Al EDI from spinach contributing 12% of the adult Al toxic-reference dose and 4% of the children’s value (the 12% figure is from the cited reference, not measured in this study). Methodologically useful as a study that pairs ICP-OES occurrence with EDI/THQ/HI/TCR computation in the native fresh-weight basis with the standard 240 g/day Malaysian adult intake assumption.

App: Pak choi, cabbage, mustard greens, and spinach from Malaysian Klang Valley wet-market sources: Cd, Cr, Cu, and Pb are data gaps under <0.004–0.01 mg/kg LODs in this single study; Al is a relevant analyte for spinach specifically. Geographic and market-channel context (urban wet-market sourcing from Selangor wholesale vs. near-farm sampling) is a key uncertainty flag — the app should not treat these non-detections as representative of all Malaysian or Southeast Asian leafy vegetables.

Wiki pages this source may touch

• lead
• cadmium
• aluminum
• chromium
• copper
• iron
• leafy-vegetables
• leafy-greens
• spinach
• cabbage

Mustard (B. juncea) routes via leafy-greens (mustard-greens is an alias on that page; no dedicated mustard-greens ingredient page in the current taxonomy). Pak choi (B. rapa var. chinensis) likewise routes via leafy-greens / leafy-vegetables in the absence of a dedicated pak-choi ingredient page; auto-stub at freq ≥ 2 will surface the slug if the corpus accumulates sufficient pak-choi-specific evidence.

Verification notes

• 2026-05-20 — Merge-enhance pass against the source PDF (raw/Manual Fetch Kimi /02_Vegetables_and_Vegetable_Products/02_Vegetables_and_Vegetable_Products/Heavy Metals Assessment in Selected Leafy Vegetables from Malaysian Wet Markets.pdf). Prior page version (updated 2026-05-13) had several defects that have been corrected here:
  • metals: previously listed [Al, Cd, Cr, Pb, Fe] — missing Cu, even though the paper measures six metals (Al, Cd, Cr, Cu, Fe, Pb) and Table 1 reports Cu as ND <0.01 mg/kg across all vegetables. Updated to [Al, Cd, Cr, Cu, Fe, Pb].
  • raw_path: was truncated to …Malaysi.pdf; corrected to the full filename …Malaysian Wet Markets.pdf.
  • raw_handle: was the generic manual-fetch-kimi; updated to the specific MFK_heavy-metals-assessment-in-selected-leafy-vegetabl form per current convention.
  • matrices: previously listed [leafy-vegetable, fresh-weight]; fresh-weight is a basis, not a matrix, and has been removed. Native basis is documented narratively (fresh weight throughout).
  • ingredients: previously contained broken wikilinks [[ingredients/mustard-greens]] (alias on leafy-greens, not a page) and [[ingredients/pak-choi]] (no page). Replaced with [[ingredients/leafy-greens]] (which already aliases mustard-greens) and noted both species’ routing destination explicitly in the Wiki pages section.
  • products: previously empty ([]), triggering the products-missing routing advisory in routing_malformed.csv. Populated with [spinach, leafy-vegetables-other] — the two existing HMTc-locked Row 4 / Row 5 product pages that this paper provides direct context for. No new product pages were created (Step 0 Lock remains Karen’s call).
  • Prior Key-numbers table cell for “Pb Malaysian limit” read 0.3 (Malaysian Food Reg. 1985) — but Table 1 of the source explicitly prints N/A for the Pb Malaysian column. Corrected to N/A. The 0.3 figure shown in the prior version was a conflation with the FAO/WHO leafy-vegetable Pb limit; only the Cd row of the paper’s Table 1 carries a Malaysian limit value (1.0 mg/kg, MFR 1985 14th Schedule).
  • Replaced legacy ## Wiki pages updated on ingest heading with ## Wiki pages this source may touch per current schema.
  • Added full Table 2 (EDI) and Table 3 (THQ/HI) transcriptions so downstream synthesis can read every value rather than the narrative summaries in the prior version.
• Source-internal anomaly preserved (not a wiki defect): Table 2 of the source prints the Al “Total EDI via consumption of selected leafy vegetables” as 3.123 × 10⁻³, but the sum of the per-vegetable Al EDI values is 3.123 × 10⁻² (one decimal order higher). The latter value is independently confirmed by the source’s reported Al GTHQ (0.03123, page 228), since RfD(Al) = 1 makes the Al GTHQ numerically equal to the Al total EDI. The 3.123 × 10⁻² figure has been reported above; the table-vs-sum discrepancy is a paper-internal typo, not a data-integrity stop condition.
• Pb permissible limit text-vs-table: the source’s prose (“the permissible limits of 0.3 and 2.0 mg/kg (FAO/WHO, 2014)”) cites two values for Pb, while Table 1 prints only 0.3 for the FAO/WHO column. The 0.3 mg/kg figure is the Codex CXS 193 leafy-vegetable Pb maximum level (the row-specific limit relevant here); the 2.0 figure appears to be a non-leafy or legacy reference and is not the leafy-vegetable Codex limit. The 0.3 value is used in the wiki Key-numbers table, matching the source’s Table 1.
• Speciation discipline: the paper measures total Cr (ICP-OES, no Cr-VI separation) and does not measure As or Hg at all. metals: [Cr ...] is correct (not Cr-VI). No speciation flags required.
• Brand firewall: no brand names appear in the source or this page; the paper samples market-level vendor lots without brand attribution.
• Routing: products: [spinach, leafy-vegetables-other] routes this source as broad context to both Row 4 (clean benchmark) and Row 5 (higher-contamination sibling) of the HMTc fruits-and-vegetables category. matrices: [leafy-vegetable] retained; fresh-weight removed as it is a basis label, not a matrix.
• 2026-05-20 — Fresh-context audit subagent (verdict REVISE) flagged three findings; all three were verified against the source and corrected:
  • ❌ Check 2: [[metals/aluminium]] (British spelling) — verified against the taxonomy snapshot (line 50) and wiki/metals/: the canonical slug is aluminum (US spelling). Corrected to [[metals/aluminum]].
  • ⚠️ Check 5: “Al EDI from spinach alone contributing ~12% of the adult Al PTWI-derived MTDI” — verified against PDF p.227: this 12% (adult) / 4% (children) figure is explicitly attributed by See et al. to Martín-León et al. (2023), not to their own data. Reattributed in the Courses Implication so the cited authorship is preserved.
  • ⚠️ Check 5: “due to sourcing from cleaner growing regions (Cameron Highlands suppliers)” — verified against PDF p.217: the paper mentions Cameron Highlands as a supply region but does not conclude that the wet-market non-detections are caused by Cameron Highlands sourcing. Softened to factual mention without the causal “due to” framing.
  • The auditor’s ⚠️ on the Al Total EDI typo handling (Check 1) was explicitly noted as acceptable disclosure; no further action required.

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.