Exposure assessment of heavy metal residues in some Egyptian fruits

Overview

This study measured Pb, Cd, Cr, Cu, and Ni concentrations in 108 fresh fruit samples (apples, grapes, oranges; 36 per fruit type, 9 per governorate per fruit) 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 more than ten times the EU permissible limit. Washing grapes reduced Cu and Ni by up to ~97%; peeling oranges reduced Cu by up to ~81%. Estimated daily intake for Cu and Ni exceeded reference tolerable daily intake values in most fruit-governorate combinations.

Key numbers

Apples (n=36 total, 9 per governorate; AAS, dry-ashed at 540°C; LODs: Pb 0.1, Cd 0.02, Cu 0.03, Ni 0.1, Cr 0.06 mg/kg):

Grapes (n=36 total, 9 per governorate):

Oranges (n=36 total, 9 per governorate):

Mitigation by washing (grapes): Ni reduced by ~28% (Cairo), ~97% (Giza), ~31% (El-Fayoum), ~75% (Alexandria); Cu reduced by ~12% (Cairo), ~29% (Giza), ~58% (El-Fayoum), ~55% (Alexandria). (Values read from Fig. 1.)

Mitigation by peeling (oranges): Cu reduced by 81.36% (Cairo), 12.56% (Giza), 24.07% (Fayoum), 54.32% (Alexandria); Ni reduced 9.67% (Cairo), 22.61% (Giza), and no reduction in Fayoum or Alexandria (the source states “no reducing effect on Ni” for those two governorates without giving a numerical value). The authors interpret this as Cu being predominantly surface-bound on orange peel and Ni being more systemically absorbed in some regional samples.

Estimated daily intake (EDI) vs. tolerable daily intake (TDI) for adults (assumed BW 70 kg; WHO GEMS/Food Middle East regional consumption: apples 7.5 g/person/day, grapes 15.8 g/person/day, oranges 31.5 g/person/day; reference TDI per USEPA Region III: Cr 0.003, Cu 0.040, Ni 0.020). EDI exceeded TDI in:

• Apples: Cu (Cairo, Alexandria, Giza); Ni (Cairo, El-Fayoum).
• Grapes: Cr (Cairo, El-Fayoum); Cu (all four governorates); Ni (all four governorates).
• Oranges: Cu (all four governorates); Ni (all four governorates).

The paper’s Table 4 reports both EDI and TDI in units it labels “mg/kg/day” but the magnitudes are consistent with µg/(kg body weight·day) given the input data and formula; the EDI > TDI comparisons inside the paper remain internally consistent because both sides use the same magnitude convention.

Methods (brief)

Atomic absorption spectrophotometry (Agilent Technologies 200 Series AA) with cathode-lamp settings: Cd 228.8 nm/0.5 nm slit, Cr 357.9 nm/0.2 nm, Cu 324.8 nm/0.5 nm, Pb 283.0 nm/1.0 nm, Ni 232.0 nm/0.2 nm. Sample prep: 5 g homogenized fresh fruit dried at 105°C for 16 h, dry-ashed at 540°C for 8–12 h, dissolved in 1.0 mL 36% HCl, filtered (Whatman No. 40 ashless), made up to volume, analyzed by AAS. Reference standards from Merck (Darmstadt), prepared from 1000 mg/kg stock in 0.1 N HNO3. Limits of detection (mg/kg): Pb 0.1, Cd 0.02, Cu 0.03, Ni 0.1, Cr 0.06. Basis convention not explicitly stated, but reporting against MRLs in mg/kg and the starting material being fresh homogenized fruit indicates fresh weight (wet weight). Only total metals were measured; no arsenic species (iAs vs tAs) or mercury species (MeHg vs tHg) were reported, and Al, Sn, Sb, U were not in scope.

EDI computed as Ci × IR / BW with Ci in mg/kg, IR in g/person/day, and BW = 70 kg. Statistical analysis: one-way ANOVA with Fisher’s Protected LSD for between-governorate comparison; significance at the 1% level (per table footnotes).

Implications

Certification: Cu and Ni MRL exceedances in Egyptian-origin fresh fruit are relevant for sourcing audits. Pb and Cd were below LOD (0.1 and 0.02 mg/kg respectively) in all 108 samples; this informs but does not by itself establish a regional clean-platform claim for Pb/Cd because the AAS LOD for Pb (0.1 mg/kg = 100 ppb) is well above modern ICP-MS LODs (~1 ppb) used in HMTc-relevant comparator studies. Washing and peeling are documented mitigation levers with substantial but incomplete reduction.

Courses: Useful example of how washing and peeling reduce surface-bound metals (Cu and surface-Ni predominantly), and of the limits of these interventions when metals are systemically absorbed (Alexandria grape Ni at 1.78 mg/kg is not plausibly all surface).

App: Cu and Ni present across all 12 fruit-governorate cells; Pb and Cd not detected; Cr only in grapes from Cairo and El-Fayoum. Within-fruit-type variation across governorates is approximately 10x for Cu and 6x for Ni, large enough that regional sourcing matters for category-level risk modelling.

Verification notes

• 2026-05-20 merge-enhance pass: fixed invalid ingredient slug apples → apple (canonical singular slug per current taxonomy; wiki/ingredients/apple.md exists, apples.md does not); restored full raw_path (previously truncated to frui.pdf); added per-governorate n=9 detail; added explicit wet-weight basis note (source does not state explicitly but starting material is 5 g fresh homogenized fruit reported against fresh-weight MRLs); preserved cite_key, raw_handle, license, DOI, near_duplicates fields; added explicit EDI/TDI exceedance enumeration from Table 4; expanded washing/peeling mitigation numbers from Figs. 1–2. Paper-internal note: the abstract and main text state Giza apples Cu = 0.33 mg/kg whereas Table 1 reports 0.55 ± 0.14 mg/kg; this page follows the table value (table reports per-replicate mean ± SE and is the authoritative datum). The paper’s Table 4 labels EDI/TDI units as “mg/kg/day” but the magnitudes are µg/(kg BW·day); EDI > TDI comparisons remain internally consistent within the paper’s convention.
• 2026-05-20 audit-subagent pass (verdict REVISE): one ⚠️ applied — peeling-oranges Ni line reworded from “0% (Fayoum), 0% (Alexandria)” to “no reduction in Fayoum or Alexandria” to match the source’s “no reducing effect on Ni” phrasing (PDF p. 540 §3.2) without overstating numerical precision. One ❌ rejected as a false positive: the subagent flagged ingredients/oranges as not present in docs/gpt-collaboration/taxonomy-snapshot.md, but the snapshot’s Ingredients line does include oranges (verified: ...orange-juice,oranges,organ-meats,...) and wiki/ingredients/oranges.md exists on disk — slug is valid in both taxonomy and on-disk inventory. Checks 1 (numerical fidelity), 3 (speciation/methods), 4 (brand firewall), 5 (HMTc firewall) all clean.

Wiki pages updated on ingest

• Apple
• Grapes
• Oranges
• Fresh Fruit
• Copper
• Nickel
• Chromium

Update history

The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and 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.