Wale 2023 — Heavy metals in fruits and vegetables (International Journal of Food Science and Biotechnology)

This three-page single-author narrative review (Vol. 8, No. 2, pp. 23-25, doi 10.11648/j.ijfsb.20230802.12) summarizes secondary claims from the heavy-metals-in-produce literature, framed around the general thesis that untreated wastewater discharges from leather and textile industries, automobile lead emissions, and inadequate household waste disposal are the dominant routes by which Pb, Cd, As, Cr, Ni, and other heavy metals enter fruits, vegetables, and fruit juices at concentrations the review claims exceed WHO/FAO tolerable limits. The review presents no primary measurements; its two data tables are tertiary reproductions of values from Anwar et al. 2014 (Table 1, essential trace-element dietary reference intakes) and Ihesinachi and Eresiya 2014 (Table 2, claimed WHO/FAO tolerable limits in fruit juices). The paper carries paper-internal defects flagged below — notably a units-label inconsistency in Table 2 and an inclusion of palladium (Pd) as a major dietary heavy-metal contaminant alongside Pb/Cd/As/Cr, which is not a mainstream characterization in the heavy-metals-in-food literature. Evidence tier C: thin narrative review at a low-prestige Science Publishing Group venue with entirely tertiary data and unverified secondary citations.

Key numbers

All values below are reported by Wale as paraphrases of cited prior sources; none are original measurements.

Table 1 — Dietary reference intakes for essential trace elements (Source: ref [4] = Anwar, Mahmood, Haque 2014, FUUAST Journal of Biology; mg/day)

• Chromium (Cr): 0.05–0.1
• Iron (Fe): 15.0
• Zinc (Zn): 8.0–15.0
• Nickel (Ni): 0.4
• Manganese (Mn): 2.2–8.8
• Cobalt (Co): 0.3
• Copper (Cu): 3.2

Note: Table 1 reports total dietary intake recommendations for essential trace elements, not contamination limits. Wale does not state a population (adult vs child) or the source authority (WHO/FAO/IOM) for these reference values; the underlying ref [4] is a Pakistani undergraduate-journal compilation, not a recognized authority.

Table 2 — Claimed WHO/FAO tolerable limits in fruit juices (Source: ref [10] = Ihesinachi and Eresiya 2014, Journal Issues; units inconsistent in source — see flag below)

• Cadmium (Cd): 0.10
• Lead (Pb): 0.20
• Copper (Cu): 0.05–0.5
• Nickel (Ni): 0.14
• Cobalt (Co): 2.00
• Manganese (Mn): 0.30
• Iron (Fe): 0.80

Paper-internal unit-labeling defect: The table title states “mg/kg” while the column header states “g/kg”. The numerical magnitudes (0.10–2.00) are consistent with mg/kg, not g/kg (0.20 g/kg Pb would equal 200,000 ppb, a value no regulatory body has ever proposed for fruit juice). Treat all Table 2 values as mg/kg. The mismatch is intrinsic to the published source and is reported here without silent correction.

Authority-of-source defect: Wale attributes Table 2 to “WHO/FAO tolerable limits” but the source ref [10] is a 2014 single-site primary study (orange, pineapple, avocado pear, pawpaw from Kaani, Bori, Rivers State, Nigeria) that itself only paraphrased what the authors believed were WHO/FAO limits. Cross-checking against Codex CXS 193-1995 and FAO/WHO Codex Alimentarius general standard for contaminants in fruit juices: the Wale/Ihesinachi Pb value of 0.20 mg/kg does not match Codex (which sets Pb in fruit juices at 0.03 mg/kg per CXS 193-1995, with 0.20 mg/kg being a cereal-grain limit). Wale’s Table 2 should not be used as a citation for actual Codex or WHO/FAO regulatory values.

Narrative claims about contamination sources

• Cement-manufacturing industries enrich neighboring fruits and vegetables with Zn, Ni, Co, Cu, Cr (review’s paraphrase of ref [9] = Yaqub et al. 2021).
• Toxic metals with the greatest soil-to-plant transfer and bioaccumulation potential identified in the review: Co, Cu, Cr (paraphrase of ref [9] / [12]).
• Cd, Ni, Cr characterized as carcinogenic (paraphrase of ref [17] = Yang et al. 2019).
• Most common heavy metal contaminant identified as Pb, attributed historically to tetraethyl-lead use in petrol (paraphrase of ref [14] = Rajeswari and Sailaja 2014).
• Review states that “in most cities the accumulation of heavy metals in soil, ground water, fruits and vegetables exceeds the WHO/FAO maximum tolerable limits,” citing refs [5, 7, 9, 12]. No specific concentration values, sample sizes, or geographic specifics are given in the body for this aggregate claim.
• Review states that “concentrations of major studied metals (Fe, Mn, Cu, Zn, Pb, Cd and Hg) were exceeding than the recommended maximum acceptable levels proposed by the Joint FAO/WHO and EC Committees” (paraphrase of ref [3] = Alturiqi and Albedair 2012, which is itself a study of fish, meat, and meat products in Saudi Arabia, not fruits or vegetables — paper-internal mis-attribution flagged for downstream synthesis).

Palladium inclusion (paper-internal defect)

The review’s abstract and Section 2 list palladium (Pd) as a toxic heavy metal of concern alongside Pb, Ni, As, Cr in fruits and fruit juices. Section 2 further claims “urban areas are highly exposed to contaminate with heavy metals like Arsenic (As), Chromium (Cr), Palladium (Pd) and Lead (Pb).” Palladium is not commonly identified in the mainstream heavy-metals-in-food literature as a dietary contaminant of concern in fruits and vegetables (it appears primarily in catalytic-converter-derived urban-aerosol literature). Wale does not cite a primary source for the Pd-in-fruit claim. Flagged as outside-mainstream-framing; downstream pages should not treat this review as evidence supporting routine Pd surveillance in produce.

Methods (brief)

Single-author narrative literature review, 3 printed pages including references, no PRISMA flow, no documented inclusion/exclusion criteria, no risk-of-bias assessment, no quantitative synthesis. The review cites 17 references spanning 1992-2022, with the most recent primary studies cited being Mitra et al. 2022 (ref [11], a Journal of King Saud University-Science narrative review) and Ashraful Islam et al. 2022 (ref [5], a Bangladesh tropical-fruits primary study). The review makes no methodological distinction between essential trace minerals (Cu, Fe, Zn, Mn) and non-essential toxic heavy metals (Pb, Cd, As) when discussing “heavy metal contamination.” Evidence tier C is assigned because: (i) the paper has no original data, (ii) it is published in a Science Publishing Group journal (a publisher of recognized variable quality), (iii) its two data tables contain unit-labeling and authority-attribution defects, (iv) it includes palladium as a routine fruit-and-vegetable contaminant without supporting citation, and (v) its synthesis claims about WHO/FAO limit exceedance are aggregate paraphrases without quantitative anchoring to specific commodities, geographies, or sample sizes.

Implications

Certification: This review contributes no usable primary concentration data for HMTc threshold-setting workbench use. Its Table 2 claimed WHO/FAO limits should not be cited as Codex or FAO/WHO authority; the correct source for Codex limits in fruit juices is CXS 193-1995 directly. The review’s main wiki utility is as a citation pointer to several primary studies (Ashraful Islam et al. 2022 Bangladesh tropical fruits, Yaqub et al. 2021 Pakistan cement-industry fruits/vegetables, Ezeilo et al. 2020 Anambra State Nigeria market fruits/vegetables) that warrant separate ingestion if the wiki needs Nigerian, Pakistani, or Bangladeshi produce data.

Courses: The review is not pedagogically usable as a stand-alone teaching reference because of its data-table defects and palladium inclusion. The general framing (untreated industrial wastewater discharge as a contamination pathway into produce) is correct as a high-level narrative but is better sourced from the cited primary studies than from this review.

App: No app-ingestible data. The review’s claimed WHO/FAO Table 2 values are unreliable and should not be used as ingredient-class regulatory caps.

Wiki pages updated on ingest

• lead
• cadmium
• arsenic-total
• chromium
• nickel
• mercury-total
• copper
• iron
• manganese
• cobalt
• zinc
• fruits
• vegetables
• fruit-juice

Page history

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