Manouchehri et al. 2021 — Heavy metals in honey: systematic review (Uludag Bee Journal)

This systematic review from Iranian and Turkish authors, published in the Turkish Uludag Bee Journal, evaluates the presence of toxic and carcinogenic heavy metals in honey, covering bee uptake pathways (contaminated water, pollen, nectar, inhalation during flight, adhesion to hairy body surfaces), the health effects of consuming contaminated honey, and findings from studies across multiple countries. Bees act as biomonitors for environmental heavy metal pollution, and honey from industrial areas consistently shows higher metal levels than honey from rural regions. Key geographic findings reviewed include: in Iran, most honey samples showed low contamination but Cd and Hg exceeded permitted limits in some regions tied to industrial proximity; in Croatia and Kosovo, Pb content was higher than reported in other European countries; in Nigeria, Fe, Cu, Mn, and Zn exceeded WHO/FAO permitted levels; studies in Turkey showed a direct correlation between honey metal contamination rates and proximity to industrial centres. The review also describes Pb and Sn migration as a storage-container pathway for acidic honey.

Key numbers

The review does not generate primary concentration data. Table 1 of the review aggregates honey heavy metal measurements from 28 cited studies across 19 countries, sampling years 2010–2021. Reporting units across cited studies are heterogeneous (mg/kg, µg/kg, ppm, ppb, ng/g, mg/L) and are not harmonised in the review; consequently the table is a directional gateway rather than a pooled occurrence estimate.

Selected high-value findings as reported in Table 1 of the review (units as printed in the source):

• Iran, Markazi Province, n=25 industrial-area samples (Aghamirlou et al. 2015, ICP-OES): Pb 507.58 ± 402.14 µg/kg, Cr 899.75 ± 184.03 µg/kg, Cd 27.62 ± 32 µg/kg, Ni 651.78 ± 173.29 µg/kg — the highest Pb and Cr means in the table, attributed to industrial proximity.
• Iran, Iran-wide markets, n=15 (Sobhanardakani & Kianpour 2016, ICP-OES): Cd 63.18 ± 43.39 µg/kg, Cr 58.05 ± 30.39 µg/kg, Zn 684.43 ± 190.43 µg/kg, Al 56.15 ± 54.32 µg/kg.
• Italy, n=72 (Quinto et al. 2016, ICP-MS): Pb 32.8 ± 47.9 µg/kg, Al 1400 ± 2300 µg/kg, Fe 2080 ± 1060 µg/kg, Cr 116 ± 10.7 µg/kg.
• Croatia, n=244 (Bilandžić et al. 2011, ICP-MS): Pb 0.458 mg/kg, Cd 0.013 mg/kg, Al 288.5 mg/kg, Mn 53.1 mg/kg — the Croatian study cited as having Pb above other European values.
• Kosovo, n=80 (Fadil et al.): Pb 0.88 mg/kg, Cd 0.05 mg/kg — also flagged in the discussion as elevated against other European ranges.
• Ghana, n=20 (Magna et al. 2018, AAS): Pb 79.815 ± 16.796 mg/kg, Al 15.785 ± 10.968 mg/kg, Cu 13.855 ± 10.213 mg/kg, Mn 8.215 ± 4.452 mg/kg. The Pb value is implausibly high for honey (~80 ppm) and the review does not flag it as anomalous; treat as a data-quality concern in the cited primary source rather than as a usable occurrence point.
• China, multi-region (Tuzen et al. 2007): Cd 1.34 µg/kg, Pb 33.98 µg/kg, As 13.44 µg/kg, Hg 1.65 µg/kg.
• Chile (Fredes & Montenegro 2006, volcanic-soil region): Al 6.15 ± 4.53 mg/kg, Cd 0.01–0.05 mg/kg — Al attributed by the authors to volcanic soils.
• Hungary, n=187 (Sajtos et al. 2019): Pb 0.51 ± 0.2 mg/kg, Mn 3.32 ± 3.11 mg/kg, Al 2.53 ± 4.67 mg/kg. The review’s Table 1 method-column lists ICP-OES; the cited paper title reads “By MP-AES Method” — the review is internally inconsistent on the analytical technique for this row.

Country-level synthesis statements made by the review (not pooled occurrence numbers):

• Turkey/Iran: Cd and Hg above permitted limits in some honey samples from industrially proximate regions.
• Nigeria (Toma et al. 2020 study cited): Fe, Cu, Mn, Zn mean concentrations above WHO/FAO maximum permissible levels in honey; industrial-area honey higher than rural-area.
• Croatia/Kosovo: Pb in honey “higher than reported amounts in other European countries”, framed by the review as worrying.
• Iran (Akbari et al. 2012, Saghaei et al. 2012): Pb in honey from Iran, Ardabil, and Urmia city markets reported as 0.011, 0.935, and 0.04 mg/kg respectively; Urmia honey samples described as good quality.
• Poland, Romania, Ethiopia (Winiarska-Mieczan et al. 2021): cumulative consumption considered nutritionally safe for children and adults.
• Bhalchandra & Baviskar (India, Apis dorsata): As, Cd, Pb, Hg, and Ni detected in all honey samples, but mean concentrations below the Indian regulatory limit.
• A multi-country study cited by Altekin et al. (2015) and Piven et al. (2020) reported Cr, Zn, Fe, Ni, Mn, Pb, Cu, Cd, and Co concentrations in honey below FAO/WHO limits, posing no risk; the same studies note bee-body burden higher than honey burden for most metals, consistent with bees acting as a filter during nectar processing.

Metals covered in the review: Fe, Zn, Cu, As, Pb, Cd, Ni, Cr, Al, Mn, Co, Hg, and Sn as a storage-container pathway. Methods referenced in cited studies include ICP-OES, ICP-MS, ICP-AES, AAS, FAAS, GFAAS, HGAAS, MP-AES, FES, HPLC, and TXRF.

Bee body accumulation is reported to be higher than honey accumulation for most metals, suggesting bees filter out some contamination in the honey production process.

Methods (brief)

Systematic review using keywords “heavy metals” and “honey” in databases: Google Scholar, SID, Scopus, PubMed, Science Direct, ISI. Received July 2021, accepted September 2021. No PRISMA protocol stated. Evidence tier B: the review is a useful synthesis of honey heavy metal literature across multiple countries but lacks primary occurrence measurements, does not present pooled quantitative estimates, and the Turkish-language journal has limited indexing depth. Useful as a gateway reference for the honey contamination profile and for its geographic survey of industrial-area effects on honey quality.

Implications

Certification: This review documents contamination pathways through bee forage and storage containers and establishes that honey metal burden is geographically variable, with industrial proximity a dominant driver. It is review-level orientation evidence rather than a primary ppb occurrence dataset.

Courses: Useful for supply-chain modules demonstrating that biomonitors like bees reflect environmental contamination. Also illustrates the metal-in-packaging pathway: the review notes that acidic honey (pH ~3.9) can corrode metal containers, and soldered cans increase Pb and Sn in honey; unsealed or improperly coated storage containers are a contamination source.

App: Not a source of usable ppb values for contamination_profile. Storage container material is a relevant contamination lever for honey.

Wiki pages this source may touch

• honey
• honey
• lead
• cadmium
• mercury-total
• chromium
• nickel
• aluminum
• iron
• zinc
• copper
• arsenic-total
• manganese
• cobalt
• tin-inorganic

Verification notes

• Cross-vendor audit (Codex, 2026-05-17) expanded the metal and country scope to match the review table and discussion, removed the invalid supply-chain/packaging link, and replaced HMT&C category speculation with source-level language.
• 2026-05-18 brand-firewall recheck (Part 12, stricter reading): re-read full PDF body, abstract, ÖZ, discussion, and references against the wiki page. No commercial honey brand names appear in the source or in the wiki page; the cited Akbari et al. 2012 study title references “Iranian Honey Brands” but the review body presents only country/region/market identifiers (Iran, Ardabil, Urmia, Saveh City, Markazi Province, Tadla-Azilal, etc.). Firewall passes.
• 2026-05-18 merge-enhance: added Chile (CL) and China (CN) to jurisdictions to match the Fredes & Montenegro 2006 (Chile) and Tuzen et al. 2007 (China) studies discussed in the body text, and expanded Key numbers with quantitative Table 1 highlights so the page is usable as a directional gateway to the cited primary sources.
• The review does not provide arsenic or mercury speciation; this page treats those entries as total arsenic (tAs) and total mercury (tHg).
• Sn is included only for the storage-container leaching pathway discussed by the review, not as a pooled honey occurrence estimate.
• Table 1 of the review contains internal anomalies (cross-unit inconsistencies, e.g., the “UT 2015” Turkey row reporting Pb 110 ± 1.277 mg/kg wet weight in the table, which is implausible and the review does not flag; and Magna et al. 2018 Ghana Pb 79.815 ± 16.796 mg/kg, a comparable-magnitude implausible value). The Key numbers section flags these magnitudes rather than treating them as usable occurrence points.
• 2026-05-18 audit-subagent finding (verified against Table 1 column order on PDF p.240): the prior Magna et al. 2018 Ghana bullet transposed Pb and Ni — the 79.815 ± 16.796 value sits in the Lead column, not the Nickle column. Corrected, and the false WHO/FAO Ni-exceedance synthesis statement that accompanied it (the actual WHO/FAO-exceedance statement in the review is for Toma et al. Nigeria Fe/Cu/Mn/Zn, not Magna Ghana Ni) was removed. The audit subagent also flagged the Aljedani Saudi Arabia bullet for attribution ambiguity between Table 1 and the discussion text (the same “0.008 ± 0.008” value is attributed to Aljedani in Table 1 and to Saghaei in the p.242 discussion); the bullet was dropped because the review’s internal inconsistency makes it unusable as a citation. Sajtos Hungary method label was reconciled by noting Table 1 (ICP-OES) and the cited paper title (MP-AES) disagree.

Page history

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