Izah et al. 2016 — Heavy metals in beverages consumed in Nigeria

Izah and colleagues (Niger Delta University, Bayelsa State, Nigeria) review the published literature on heavy metal concentrations in alcoholic and non-alcoholic beverages consumed in Nigeria between 2007 and 2016. The review tabulates concentration ranges from 13 underlying non-alcoholic studies (Table 1) and 5 underlying alcoholic-beverage studies (Table 2), compared against the Standard Organization of Nigeria (SON) and WHO drinking-water guideline limits. The review reports no new measurements, treats drinking-water limits as the reference framework for evaluating beverages, and discusses qualitative health implications for each heavy metal.

Key numbers

This is a narrative review with no new measurements. All values reported below are concentration ranges (mg/L unless noted) reproduced from the review’s Tables 1 and 2, attributed to the underlying primary studies the review compiled. Concentration values are reported as ranges (low–high across the underlying sample sets). The review does not provide pooled per-analyte means across studies.

Table 1 — Non-alcoholic beverages (mg/L unless noted)

Compiled by Izah et al. from 13 underlying Nigerian studies. Categories below describe the beverage type at the product-form / category level; brand names appearing in the source tables are omitted per CLAUDE.md Part 12 brand-firewall (strict reading locked 2026-05-17).

SON drinking-water limit row (Table 1, reference [37]): Fe 0.3 / Zn 3 / Cd 0.003 / Cr 0.05 / Pb 0.01 / Hg 0.001 / Cu 1 / Ni 0.02 / Mn 0.2 / As 0.01 mg/L. WHO drinking-water guideline row (Table 1, reference [38]): Cd 0.003 / Cr 0.05 / Pb 0.01 / Hg 0.001 / Cu 2 / Ni 0.07 / Sn 0.002 / As 0.01 / Sb 0.02 mg/L. The review applies these drinking-water values as reference limits for beverages.

The four asterisked rows in PDF Table 1 (fruit juices and soft drinks broad mixed list, canned soft drinks broad mixed list, canned milk beverages, and canned dairy and juice beverages) are reported as µg/mL per the table footnote ”* Expressed as µg/mL”; the underlying sources for these four rows are Roberts and Orisakwe 2011 (reference [26]) and Eno-obong and Ukoha 2013 (reference [54]). 1 µg/mL is numerically equal to 1 mg/L for these units, so the canned-milk Sn range of 217.6–516.0 µg/mL is more than five orders of magnitude above the WHO 0.002 mg/L drinking-water Sn limit; the review does not explicitly flag this magnitude gap and reports the value as the underlying source published it. The two non-asterisked Sn rows reported by Maduabuchi et al. 2007 (reference [40]; 0.003–0.161 and 0.002–0.261) are in mg/L per the table header.

Table 2 — Alcoholic beverages (mg/L)

Compiled by Izah et al. from 5 underlying Nigerian studies.

SON and WHO drinking-water limit rows reproduced unchanged from Table 1.

Exceedance summaries cited in Section 4.11

The review reproduces percentage-exceedance figures from underlying studies:

• Maduabuchi et al. [29], 21 canned + 30 non-canned beverages: Fe exceedance 95.25% canned / 75.86% non-canned; Mn 42.86% / 51.72%; Ni 80.95% / 72.41%.
• Magomya et al. [30], 24 soft drinks: 53.33% Fe, 7.14% Cu, 20.83% Cr, 29.17% Pb, 16.67% Cd above MCL.
• Orisakwe and Ajaezi [36], 30 energy drinks (locally manufactured and imported): 66.7% Pb, 36.7% Cr, 70% Co above WHO limits; 33.3% had negligible daily-intake-level lead.
• Ogunlana et al. [15], 10 soft drinks: 70% of 6 heavy metals (As, Cd, Pb, Zn, Cu, Fe) exceeded WHO permissible limits.
• Roberts and Orisakwe [26], 38 fruit juices and soft drinks: 0% Sb, 86.5% Sn, 89.2% Hg exceeded WHO desirable limits.
• Maduabuchi et al. [40], 21 canned + 30 non-canned beverages: 33.3% canned / 55.2% non-canned exceeded US EPA MCL for As; 68.9% / 76.2% exceeded for Cr.

Evidence Fitness

This source is a narrative review of secondary data. It contributes no primary occurrence measurements and is not eligible for pooled-percentile work on any product row. It functions as: (1) a discovery anchor for the 2007–2016 Nigerian beverage heavy-metals literature, (2) a category-level qualitative picture of which metals exceed SON / WHO drinking-water limits in which beverage categories sold in Nigeria, and (3) a list of primary papers (Engwa et al. [39]; Salako et al. [44]; Adegbola et al. [52]; Ubuoh [27]; Maduabuchi et al. [29, 40]; Magomya et al. [30]; Ogunlana et al. [15]; Adepoju-Bello et al. [41]; Iweala et al. [1]; Udota and Umuodofia [43]; Robert and Orisakwe [26]; Eno-obong and Ukoha [54]; Nnorom et al. [23]; Garba et al. [16]; Igwemmar et al. [18]) worth ingesting individually if any becomes a candidate input for synthesis on the soft-drinks, fruit-juice, beer, or herbal-drink rows. Reported public evidence label: Context only.

The review uses drinking-water limits (SON and WHO) as the comparison framework for finished beverages. This is the methodological choice the review itself makes and reports (Section 4, paragraph 2: “the reference limits for heavy metal in beverages including alcoholic and non-alcoholic drinks, fruit juices, candy have been generally compared with potable water limits”). Drinking-water limits are not finished-beverage food safety limits, and the review does not propose finished-beverage limits of its own.

Methods (brief)

Narrative review. Section 2 states the methodology in full: “In this study secondary data from Internet sources was used. Literature reports on the concentration of heavy metals in alcoholic and non-alcoholic beverages consumed in Nigeria between 2007 and 2016 was assessed. The mean and/or range data was extracted and presented in Tables 1 and 2 in Section 4. The concentration of heavy metals in beverages is usually assessed based on drinking water guidelines [30]. As such, the concentrations were discussed based on limits of the Standard Organization of Nigeria [37] and World Health Organization [38].”

The review does not state a systematic search strategy, database list, inclusion/exclusion criteria, deduplication procedure, or PRISMA flow diagram, and does not present pooled-by-analyte statistics across the underlying studies. It is a narrative review rather than a systematic review or meta-analysis. The review does not independently verify any value reported in its Tables 1 and 2 against the original studies’ methods, sample size, sampling year, analytical instrument, detection limit, or speciation; the values are reproduced as the underlying papers reported them.

Implications

• Certification: contributes no direct occurrence data to soft-drinks-carbonated-beverages, fruit-juice-not-canned, fermented-beverages-non-tea-based, or herbal-botanical-infusions. The Nigerian beverage primary literature this review aggregates should be ingested directly from the cited primary papers if any becomes a candidate input for synthesis on those rows.
• Courses: useful as a teaching reference for the Nigerian beverage-contamination landscape circa 2016 and for the SON-versus-WHO drinking-water reference frame the review uses.
• App: contributes no per-product concentration values; downstream consumers should source values from the original primary papers.
• Discovery: the reference list contains 64 entries; the Nigerian beverage primary papers most likely to warrant their own ingest are reference [39] Engwa et al. 2015 (soft drink contamination, Toxicology Reports), [40] Maduabuchi et al. 2007 (As and Cr in canned and non-canned beverages, Int. J. Environ. Res. Public Health), [44] Salako et al. 2016 (metals in alcoholic and non-alcoholic canned drinks, Idiroko border), [29] Maduabuchi et al. 2008 (Fe, Mn, Ni exposure from beverages, J. Health Sci.), [30] Magomya et al. 2015 (metal contaminants in Nigerian soft drinks, Int. J. Innov. Sci. Eng. Technol.), [15] Ogunlana et al. 2015 (heavy metal analysis of soft drinks, J. Glob. Biosci.), [41] Adepoju-Bello et al. 2012 (metallic impurities in soft drinks in Lagos, Afr. J. Biotechnol.), [54] Eno-obong and Ukoha 2013 (Sn and Al in canned foods and beverages, Chem. Mat. Res.), [36] Orisakwe and Ajaezi 2014 (energy drinks, Malays. J. Nutr.), and [26] Roberts and Orisakwe 2011 (Sb, Sn, Hg dietary toxicity in Nigerian beverages, QScience Connect).

Provenance notes

Open-access article distributed under CC BY 4.0 (license declaration on page 15 of the PDF). Received 6 November 2016; accepted 18 December 2016; published 22 December 2016. Toxics is an MDPI peer-reviewed journal. The cite-key uses the first-author surname “izah” (Sylvester Chibueze Izah, corresponding author) and year 2016 reflecting the online publication date; the journal cover prints “Toxics 2017, 5, 1” because the article opens volume 5. Accessed via the Manual Fetch Discovery autopilot.

The DOI 10.3390/toxics5010001 resolves to the MDPI article landing page. Editorial review: David Bellinger (academic editor). Affiliations: Department of Biological Sciences, Faculty of Science, Niger Delta University, Wilberforce Island, Yenagoa P.M.B. 071, Bayelsa State, Nigeria.

Evidence tier set to C. The source is a narrative review (no new data, no systematic methodology), and its Tables 1 and 2 reproduce values from underlying primary studies without independent verification, without method standardisation, and without pooled statistics. It functions as discovery and narrative reference; primary occurrence claims should be sourced from the cited primary papers, not from this review.

Wiki pages this source may touch

• lead
• cadmium
• arsenic
• mercury
• chromium
• nickel
• tin
• antimony
• copper
• manganese
• zinc
• soft-drinks-carbonated-beverages
• fruit-juice-not-canned
• fermented-beverages-non-tea-based
• herbal-botanical-infusions

Verification notes

No brand names appear in the source-page body. The underlying Tables 1 and 2 in the source PDF name many commercial brands of Nigerian and imported beverages (soft drinks, fruit drinks, malt drinks, beers, gins) as the sample sets the underlying primary studies analysed. Per CLAUDE.md Part 12 brand-firewall (strict reading locked 2026-05-17), brand-by-brand listings are not reproduced in the wiki. The Tables 1 and 2 reproduced above describe each row at the product-form / category level (e.g., “Twenty-four selected soft drinks”, “Canned beer composite”); brand names are dropped throughout, including the underlying Eno-obong and Ukoha 2013 row originally labelled “Olympic and Three Crown milk” (now “Canned milk beverages”) and the underlying ref [54] row originally labelled “peak, milo and five alive juice drink” (now “Canned dairy and juice beverages”). The brand-count annotations (“n=8 brand mix”, “21 brands”, “38 brands per source”) that appeared in an earlier revision of this page were wiki-introduced numbers that did not match the PDF brand lists; they have been removed.

The source tin value of 217.6–516.0 µg/mL for canned milk beverages (Eno-obong and Ukoha 2013, reference [54]) is verified against page 7 of the source PDF (Table 1) and is reproduced as the review prints it. The magnitude (≥217.6 mg/L, more than 100,000× the WHO 0.002 mg/L drinking-water Sn guideline) is implausibly high for a finished canned milk product and likely reflects a unit-of-measure or significant-figure issue in the underlying Eno-obong and Ukoha 2013 paper; the review does not flag this and does not propose a correction. The value is reported here as the review prints it; any future direct ingest of the Eno-obong and Ukoha paper should re-derive the canned-milk tin concentration from the original measurements and units.

Mercury concentrations in the broad soft-drink list (ND–11.33 mg/L, attributed to Engwa et al. [39]) are likewise implausibly high relative to the WHO 0.001 mg/L drinking-water guideline; the review reproduces the value as the underlying source published it. The same caveat applies — direct ingest of Engwa et al. 2015 should re-verify the value.

The metals: frontmatter lists Pb, Cd, tAs, tHg, Cr, Ni, Sn, Sb, Cu, Mn, Zn. The review uses “As” and “Hg” without speciation labels; per CLAUDE.md Part 14 non-negotiable speciation convention, these are recorded as tAs and tHg (total arsenic and total mercury) since no inorganic-arsenic or methylmercury determination is documented in the review. Cr is recorded as elemental Cr (the review does not specify Cr-VI vs Cr-III). Fe is omitted from metals: because Fe is not one of the HMI tracked analytes per CLAUDE.md Part 14; the iron values are retained in the body tables for completeness.

The ingredients: frontmatter is empty. The review discusses palm sap, sorghum, millet, maize, rice, wheat, acha (Digitaria exilis), Hibiscus sabdariffa, hops, barley, and water as beverage feedstocks, but the underlying Tables 1 and 2 report finished-product values rather than ingredient values, and none of these feedstocks is mapped to an HMI primary tracking ingredient at the finished-beverage scope.

The products: frontmatter maps to four existing umbrella product slugs: soft-drinks-carbonated-beverages (Tables 1 rows covering Sprite/Fanta/Coke/Pepsi-class soft drinks), fruit-juice-not-canned (Tables 1 rows covering juice and milkshake categories), fermented-beverages-non-tea-based (Table 2 rows covering beer, lager, stout, locally brewed gin, and the ethanolic herbal drink), and herbal-botanical-infusions (the agbo jedi jedi rows in both tables). No beer-specific, palm-wine-specific, or energy-drink-specific product page exists in the current taxonomy; routing relies on the umbrella slugs.

The matrices: list includes non-alcoholic-beverages and alcoholic-beverages (the review’s own top-level categories), soft-drink, fruit-juice, herbal-drink, beer, palm-wine, and canned-beverage to support sub-category routing. These are free-form bare strings consistent with the active-corpus matrices vocabulary.

The jurisdictions: list includes NG (Nigeria, the review’s geographic scope) and GLOBAL (because the SON and WHO drinking-water guideline rows used as the reference frame are international and because the imported beverages tabulated come from South Korea, China, South Africa, UAE, Germany, Belgium, Hong Kong, Pakistan, Thailand, Holland, USA, and Nigeria itself). No specific other-country jurisdiction is added because the review groups all imported beverages under the same Nigerian-consumption frame.

No HMTc threshold proposals, no consumer-audience translations, no risk advisories, and no synthesis claims of the form “this confirms the literature consensus that…” appear in the body, per CLAUDE.md Part 2 wiki/HMTc firewall.

Audit subagent (2026-06-06) raised three ❌ Part 12 findings against the initial revision (three Table 1 row labels still carrying brand names: “cocacola/Amstel/Fanta/malta Guinness/Maltina”; “Olympic and Three Crown milk”; “peak/milo/five alive juice”). All three verified against PDF page 7 and applied: each row label was rewritten to the product-form descriptor alone, matching the strict reading. The audit also raised three ⚠️ Check 1 findings against the Sn-units note: (1) the parenthetical “(0.003–0.261)” was a compression of two separate ref-[40] rows; (2) attribution to “Eno-obong and Ukoha 2013, reference [54]” was wrong because those two Sn values are reference [40] (Maduabuchi et al. 2007); (3) the µg/mL unit claim does not match the PDF asterisk-scoped footnote (ref-[40] rows are not asterisked, so are in mg/L per the table header). All three verified against PDF page 8 and applied: the note was rewritten to scope the µg/mL footnote to the four asterisked rows only and to clarify that the two ref-[40] rows are in mg/L. The audit also raised ⚠️ findings on five wiki-introduced brand-mix counts (n=8 / n=8 / n=5 for Table 2; “21 brands” and “38 brands per source” for Table 1) that did not match the PDF brand lists; all five verified against PDF pages 7 and 9 and applied by removing the count annotations rather than recounting (the source itself does not number the brand mixes, and reintroducing counts would be wiki annotation rather than source content).

Page history

The five most recent substantive edits to this page. 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.