Amer et al. 2019 — Heavy metal exposure assessment in Egyptian apples, grapes, and oranges
This study measured Pb, Cd, Cr, Cu, and Ni concentrations in 108 fresh fruit samples (apples, grapes, oranges) collected from four governorates in Egypt (Cairo, Giza, Alexandria, El-Fayoum). Lead and cadmium were not detected in any sample. Copper and nickel were present in all samples, frequently above WHO/FAO maximum residue limits. Chromium was detected only in grape samples from Cairo and El-Fayoum at concentrations exceeding EU permissible limits. Washing grapes reduced Cu and Ni by up to 97%; peeling oranges reduced Cu by up to 81%.
Key numbers
Apples (n=36, AAS, dry-ashed; LODs: Pb 0.1, Cd 0.02, Cu 0.03, Ni 0.1, Cr 0.06 mg/kg):
| Metal | Cairo | Giza | Alexandria | El-Fayoum | MRL |
|---|---|---|---|---|---|
| Pb | ND | ND | ND | ND | 0.10 mg/kg (EU 1881/2006) |
| Cd | ND | ND | ND | ND | 0.05 mg/kg |
| Cr | ND | ND | ND | ND | 0.10 mg/kg |
| Cu | 1.63 ± 0.22 | 0.55 ± 0.14 | 0.89 ± 0.28 | 0.14 ± 0.03 | 0.20 mg/kg (WHO/FAO) |
| Ni | 0.36 ± 0.12 | 0.19 ± 0.06 | 0.11 ± 0.03 | 0.34 ± 0.11 | 0.20 mg/kg |
Grapes (n=36):
| Metal | Cairo | Giza | Alexandria | El-Fayoum | MRL |
|---|---|---|---|---|---|
| Pb | ND | ND | ND | ND | 0.10 mg/kg |
| Cd | ND | ND | ND | ND | 0.05 mg/kg |
| Cr | 1.01 ± 0.04 | ND | ND | 1.06 ± 0.06 | 0.10 mg/kg |
| Cu | 3.52 ± 0.74 | 0.72 ± 0.07 | 2.53 ± 0.98 | 3.21 ± 0.86 | 0.20 mg/kg |
| Ni | 0.30 ± 0.05 | 0.83 ± 0.31 | 1.78 ± 0.77 | 0.31 ± 0.08 | 0.20 mg/kg |
Oranges (n=36):
| Metal | Cairo | Giza | Alexandria | El-Fayoum | MRL |
|---|---|---|---|---|---|
| Pb | ND | ND | ND | ND | 0.10 mg/kg |
| Cd | ND | ND | ND | ND | 0.05 mg/kg |
| Cr | ND | ND | ND | ND | 0.10 mg/kg |
| Cu | 2.20 ± 0.95 | 0.64 ± 0.05 | 0.81 ± 0.11 | 0.36 ± 0.01 | 0.20 mg/kg |
| Ni | 0.31 ± 0.02 | 0.38 ± 0.03 | 0.16 ± 0.05 | 0.06 ± 0.02 | 0.20 mg/kg |
Mitigation: Washing grapes reduced Ni by 28–97% (governorate-dependent); Cu reduced by 19–75%. Peeling oranges reduced Cu by 13–81%.
Estimated daily intake (EDI) vs. tolerable daily intake (TDI): EDI for Cu and Ni in multiple governorates exceeded TDI values (TDI: Cr 0.003, Cu 0.040, Ni 0.020 mg/kg/day per USEPA Region III).
Methods (brief)
Atomic absorption spectrophotometry (Agilent Technologies 200 Series AA). Dry-ashing at 540°C; digestion in 36% HCl. LODs: Pb 0.1, Cd 0.02, Cu 0.03, Ni 0.1, Cr 0.06 mg/kg (wet weight). Note: only total metals measured; no arsenic or mercury speciation. No iAs, tHg, Al, Sn, U reported.
Implications
Certification: Cu and Ni MRL exceedances in Egyptian-origin fresh fruit are relevant for sourcing audits. Pb and Cd were not detected in these samples, consistent with the pattern of Egyptian horticultural soils being cleaner for these analytes. Washing and peeling are documented mitigation levers.
Courses: Good example of how washing and peeling reduce surface-bound metals (Ni and Cu predominantly surface-contaminated), but limits of these interventions (some Ni appears systemically absorbed in Alexandria grape samples).
App: Cu and Ni present across all fruit types; Pb and Cd not detected. Chromium only in grapes from two of four regions. Regional variation is substantial.