Rashid and Yaacob 2015 — Metal contamination in rock melon and coco peat from Malaysian farms

Rock melon fruits (Cucumis melo, cultivar ‘Glamour’, n=70) from five Malaysian farm locations — selected because preliminary testing had already shown elevated metals — were analyzed for Al, B, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn by ICP-OES. Six of the ten elements (Al, Cr, Cu, Fe, Pb, Zn) exceeded Malaysian Food Act (1983) / Malaysian Food Regulation (1985) maximum allowable limits (MALs) in the fruit; B, Mn, and Ni did not exceed; Co was not detected. The coco peat growth medium used in the fertigation system also showed elevated metals (Al, Cu, Fe, Mn, Ni, Pb above MAL in coco peat), which the authors propose as a contamination pathway pending confirmatory work.

Key numbers

Concentrations in Cucumis melo (means ± SD across 5 farms, ppm = mg/kg in the analyzed sample; basis not explicitly stated by source — see Methods):

Per-farm Pb means (Table 2): Mantin-1 1.81, Mantin-2 1.89, Mantin-3 1.78, Klang-1 1.74, Klang-2 1.82 ppm. Mean Pb range across farms 1.74–1.89 ppm. Mean Pb across all 70 fruits 1.82 ppm; SPI/MPI/PI risk indices were not reported.

Note: Cr measured as total chromium; no Cr-VI speciation performed. Pb, Al, and Ni are HMT&C target analytes; Cr-VI is on the HMT&C list but only total Cr was measured here, so this paper does not contribute to Cr-VI evidence. Cu, Fe, Mn, Zn, B, and Co are not HMT&C analytes but are reported for completeness.

Comparison with international limits in mg/kg: Pb 1.82 mg/kg is ~18× the EU Regulation 1881/2006 limit for fruits (0.10 mg/kg), and exceeds the Malaysian MAL of 0.50 mg/kg by ~3.6×. The Malaysian MAL for Pb in fruit (0.50 mg/kg) is itself permissive relative to EU and Codex limits.

Sampling caveat: farms were chosen because preliminary tests had already shown elevated metals. These values are not representative of typical Malaysian rock melon retail and are upper-bound, biased outlier values rather than a national survey.

Methods (brief)

Sampling: completely randomized design with 14 fruit replications per location across 5 farms (3 farms at Mantin, Negeri Sembilan; 2 farms at Jalan Kebun, Klang, Selangor). Coco peat samples (70 used as growth medium plus 14 fresh-before-use) collected from the same farms.

Instrument: Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) at the soil laboratory, Faculty of Applied Science, Universiti Teknologi MARA (UiTM), Shah Alam. The paper does not describe sample preparation (acid digestion protocol, drying schedule, particle size), instrument operating conditions, calibration standards, limits of detection, recovery checks, or QA/QC procedures. Statistical reporting is limited to per-cell means with SDs and asterisk codes for significance vs. MAL (* p<0.05, ** p<0.01, *** p<0.001) but the test underlying those flags is not named.

Basis ambiguity: the paper reports concentrations in “ppm” without specifying wet vs. dry weight. Fe 102.62 ppm and Al 60.14 ppm in fresh melon flesh are implausibly high if interpreted as wet weight (typical fresh melon Fe is ~1–5 ppm wet weight, Al typically <1 ppm wet weight), suggesting either a dry-weight basis or a substantial methodological artefact (e.g., inadequate washing, surface contamination from soil/coco-peat residue, or contamination during digestion at the soil lab). The paper itself draws no distinction. Coco peat values (Table 1: Al 1220 ppm, Fe 210.53 ppm) are consistent with dry-weight reporting in a substrate context.

Evidence tier B: regional journal (Jurnal Intelek, UiTM Perlis), no DOI, methods reporting is thin, sample selection is explicitly biased toward known-contaminated farms.

Implications

Certification: Pb at 1.82 mg/kg in rock melon from these contaminated Malaysian farms is approximately 18× the EU Regulation 1881/2006 fruit limit (0.10 mg/kg) and exceeds the Malaysian MAL by ~3.6×. However, farm-selection bias plus basis ambiguity preclude using these values as evidence of typical Malaysian rock-melon contamination. Useful only as upper-bound outlier evidence and as illustration of a contaminated-growing-medium pathway in fertigation systems.

Courses: Useful illustration of (a) coco-peat growing medium as a metal contamination vector in soilless/fertigation cultivation, (b) the importance of basis specification (wet vs. dry weight) in interpreting reported ppm values, and (c) how biased farm selection limits the inferential reach of a contamination survey.

App: Not suitable for typical contamination profiling of melons given biased farm selection and basis ambiguity. Provides upper-bound outlier context only.

Wiki pages this source may touch

• lead
• chromium
• aluminum
• nickel
• copper
• iron
• zinc
• manganese
• cobalt
• melon

Verification notes

• 2026-05-20 merge-enhance pass against full PDF (pages 33–36): corrected ingredient slug melons → melon (the wiki ingredient page is singular wiki/ingredients/melon.md); corrected metal-page wikilink aluminium → aluminum to match the actual wiki page slug; expanded metals: frontmatter from [Al, Cr, Pb, Ni] to the full ten elements the paper measured; fixed truncated raw_path (missing closing parenthesis and .pdf segment); corrected the body note that previously stated “Al is not among the 10 HMT&C target analytes” (Al is on the HMT&C 10-analyte list per CLAUDE.md Part 14); added per-farm Pb means from Table 2; flagged basis ambiguity (paper does not state wet vs. dry weight); expanded Methods to note absent QA/QC, digestion, calibration, and LOD reporting; added EU comparator for Pb; renamed routing section from “Wiki pages updated on ingest” to “Wiki pages this source may touch” per Part 5b (model does not maintain routing by hand).
• Part 12 (brand firewall) re-check: paper identifies sampling locations by geography (Mantin, Negeri Sembilan; Jalan Kebun, Klang) and by cultivar name (‘Glamour’), not by commercial brand owner. The Star newspaper reference is a citation to a news article; no brand-by-brand contamination tables are reproduced. No firewall issue.
• Fresh-context audit subagent (2026-05-20) verdict REVISE: one ⚠️ on Check 3 (Speciation/Methods) flagging that the body sentence “Pb, Al, Cr, and Ni are HMT&C target analytes (Cr-VI only on the list, but only total Cr was measured here)” was internally self-correcting but initially misstated Cr as an HMT&C analyte. Verified against CLAUDE.md Part 14: the HMT&C 10-analyte list contains Cr-VI, not total Cr. Applied the suggested clearer phrasing. Checks 1 (numerical fidelity, including per-farm Pb means against Table 2 and no transposition with Table 1 coco peat values), 2 (slug vocabulary), 4 (Part 12 brand firewall), and 5 (Part 2 wiki/HMT&C firewall) all came back ✅ clean. 1 ⚠️ applied, 0 ❌ findings.

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.