Rashid and Yaacob 2015 — Metal contamination in rock melon and coco peat from Malaysian farms
Rock melon fruits (Cucumis melo, n=70) from five Malaysian farm locations known from preliminary testing to exceed maximum allowable limits (MAL) 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) MALs in the fruit. Lead was found at 1.82 ± 0.235 ppm (mean), approximately triple the MAL; chromium at 6.42 ± 0.170 ppm, exceeding the limit; aluminum at 60.14 ± 0.393 ppm. The coco peat growth medium also showed elevated metals, suggesting the growing medium as a contamination pathway. Co was not detectable by ICP-OES.
Key numbers
Concentrations in Cucumis melo (means ± SD, ppm = mg/kg):
| Element | Mean ± SD (ppm) | Exceeds MAL? |
|---|---|---|
| Al | 60.14 ± 0.393 | Yes |
| Cr | 6.42 ± 0.170 | Yes |
| Cu | 17.4 ± 0.079 | Yes |
| Fe | 102.62 ± 0.114 | Yes |
| Pb | 1.82 ± 0.235 | Yes (~3× MAL) |
| Zn | 11.97 ± 0.821 | Yes |
| B | detectable | No |
| Mn | detectable | No |
| Ni | detectable | No |
| Co | not detected | — |
Note: Cr measured as total chromium; no Cr-VI speciation performed. Al and Fe are not among the 10 HMT&C target analytes; Pb and Cr are.
Basis: wet weight (fresh fruit), ppm = mg/kg. Sample selection was biased toward known high-contamination farms.
Methods (brief)
ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometry) at UiTM Shah Alam Faculty of Applied Science. Completely randomized sampling design with 14 replications across 5 locations. Study published in Jurnal Intelek (evidence tier B: limited-scope regional journal, Universiti Teknologi MARA). Important caveat: farms were selected because preliminary tests showed elevated metals; this is not a random national survey and values are not representative of typical Malaysian rock melon retail.
Implications
Certification: Lead at 1.82 mg/kg in rock melon from contaminated Malaysian farms substantially exceeds any international food safety limit (EU limit 0.10 mg/kg for fruiting vegetables; Malaysian MAL also exceeded). However, farm selection bias limits generalizability.
Courses: Useful illustration of fertigation/coco-peat growing medium as a metal contamination pathway; also illustrates that high Pb in fresh fruit can occur through soil/substrate contamination.
App: Not suitable for typical contamination profiling of melons given biased farm selection. Provides upper-bound outlier context only.