Heavy Metal Content and Associated Health Risks in Selected Energy Drinks Sold in Birnin Kebbi, Nigeria

Overview

Yahaya and colleagues (Federal University Birnin Kebbi, Kebbi State, Nigeria) quantified five metals (zinc Zn, copper Cu, lead Pb, iron Fe, cadmium Cd) in one hundred and twenty canned energy-drink samples representing three popular commercial brands (anonymised here as Brands A, B, and C) purchased from retail outlets in Birnin Kebbi, Northwestern Nigeria over March–April 2021. Samples were acid-digested with concentrated nitric acid then analysed by atomic absorption spectrophotometry (PG-990 AAS). The authors computed Average Daily Intake (ADI), Hazard Quotient (HQ) for non-carcinogenic risk, and Carcinogenic Risk (CR) using ingestion-rate and body-weight inputs drawn from prior Nigerian dietary-risk literature, with oral reference doses from Iwuanyanwu & Chioma (2017) and cancer slope factors from Masok et al. (2017). The authors report (Results section, journal p. 29; Conclusion, journal p. 30; Table 5) that Fe and Cd exceeded the cited WHO drinking-water permissible limits in all three brands, that Cu exceeded the limit only in Brand A (Cu was reported as Not Detected in Brands B and C), and that the source’s text frames Pb as exceeding the WHO drinking-water limit only in Brand C — although Brands A and B both report Pb at 0.012 mg L⁻¹, which numerically exceeds the cited 0.01 mg L⁻¹ cap by approximately 20% (the source’s “only Power Horse” framing therefore reflects practical-significance rounding rather than strict numerical exceedance, and the discrepancy between the source’s Conclusion text and its own Table 5 is flagged in Verification notes). Zn was within the WHO drinking-water limit in every brand. The source’s abstract additionally claims that “Fe, Cu, and Cd were above the permissible limits in all the energy drinks,” which contradicts the same paper’s Results section, Conclusion, and Table 5 with respect to Cu; the Results-section / Table-5 / Conclusion reading is followed throughout this wiki page and the abstract-vs-results discrepancy is flagged in Verification notes. ADI for all five metals remained below the cited recommended daily intake (RDI) values in all three brands, but HQ for Cd exceeded the negligible-hazard threshold (HQ > 1) in every brand, HQ for Pb exceeded the threshold in Brand C, HQ for Cu exceeded the threshold in Brand A, and CR for Cd exceeded the United States Environmental Protection Agency (USEPA) tolerable threshold of 1×10⁻⁶ in every brand and for Pb in Brand C.

Key numbers

All concentrations are reported in the source as mg L⁻¹ on a beverage-as-consumed basis (samples were undiluted canned ready-to-drink energy drinks). The cited WHO drinking-water reference values (Table 5 final row, attributed to WHO 2014) are Zn 5.00, Cu 0.05, Pb 0.01, Fe 0.1, Cd 0.02 mg L⁻¹. The source does not report instrument-method limits of detection or limits of quantification; “Not Detected” (ND) is reported for Cu in two of the three brands and is treated here as left-censored at the unspecified instrument detection floor. The brand identifiers used by the source are three named commercial canned energy drinks; (brand firewall, strict reading locked 2026-05-17) the brand names are not reproduced in this wiki page body and the three brands are referred to throughout as Brand A, Brand B, and Brand C. The per-brand source-to-anonymised mapping is held in the verification notes only and is not load-bearing for any wiki claim.

Heavy metal concentrations in the three brands of canned energy drinks (Table 5, p. 9 of source PDF / journal p. 34, mg L⁻¹, mean ± SD across n=40 samples per brand)

Per-analyte detected ranges across the three brand-level means (mg L⁻¹):

• Zn: 0.937 (Brand B) – 1.005 (Brand A); all three brands below the cited WHO drinking-water limit of 5.00 mg L⁻¹.
• Cu: ND (Brands B and C) – 14.041 (Brand A); Brand A exceeds the cited WHO drinking-water limit of 0.05 mg L⁻¹ by approximately 280-fold (the source labels this finding as “non-permissible”). Brands B and C are reported as Not Detected.
• Pb: 0.012 (Brands A and B) – 0.323 (Brand C); Brands A and B exceed the cited WHO drinking-water limit of 0.01 mg L⁻¹ marginally; Brand C exceeds it by approximately 32-fold.
• Fe: 1.083 (Brand A) – 1.157 (Brand C); all three brands exceed the cited WHO drinking-water limit of 0.1 mg L⁻¹ by approximately 10- to 12-fold.
• Cd: 0.769 (Brand B) – 0.779 (Brands A and C); all three brands exceed the cited WHO drinking-water limit of 0.02 mg L⁻¹ by approximately 38- to 39-fold.

Average Daily Intake (Table 6, p. 9 of source PDF / journal p. 34)

ADI was computed as ADI = (C_drink × IR × EF × ED) / (BWT × AT), with IR = 0.5 L/day, EF = 365 days/year, ED = 30 years, BWT = 65 kg, AT = 4 680 days (= EF × ED for the non-carcinogenic ADI calculation). Values are reported in mg L⁻¹ in the source (the units label is verbatim from Table 6 footer), although the standard ADI unit is mg kg⁻¹ day⁻¹ and the equation as written produces a result in mg kg⁻¹ day⁻¹; this is a paper-internal unit-labelling caveat carried into the wiki page faithfully without recalculation (see Verification notes for the recomputation check). Dash (–) indicates ADI not reported because the corresponding concentration was Not Detected.

The source concludes that ADI for all evaluated metals is below the cited RDI threshold in every brand.

Hazard Quotient (Table 7, p. 9 of source PDF / journal p. 34)

HQ was computed as HQ = (C_drink × IR × EF × ED) / (AT × BW × RfD_oral), with the same exposure-factor inputs as for ADI and oral reference doses RfD_oral (mg L⁻¹ day⁻¹)⁻¹ from Iwuanyanwu & Chioma (2017): Zn 0.30, Cu 0.0371, Pb 0.001, Fe 0.7, Cd 0.0005. A HQ value of 1 or below is interpreted as indicating negligible non-carcinogenic hazard. Dash (–) indicates HQ not reported because the corresponding concentration was Not Detected.

HQ exceedances of the 1.0 threshold: Cd in every brand (26.35–28.00); Cu in Brand A (6.81); Pb in Brand C (4.15).

Carcinogenic Risk (Table 8, p. 9 of source PDF / journal p. 34)

CR was computed as CR = CSF × ADI using the carcinogenic-exposure inputs IR = 2.0 L/day, EF = 365 days/year, ED = 70 years, BWT = 65 kg, AT = 25 550 days (= EF × ED for the lifetime CR calculation) and cancer slope factors CSF: Zn 0.00, Cu 0.00, Pb 0.0085, Fe 0.00, Cd 6.3 (mg kg⁻¹ day⁻¹)⁻¹ from Masok et al. (2017). The USEPA tolerable CR threshold cited by the source is 1×10⁻⁶. NC = non-carcinogenic (CSF = 0).

CR exceedances of the 1×10⁻⁶ threshold: Cd in every brand (0.088, i.e., 8.8 × 10⁻² — five orders of magnitude above the tolerable threshold); Pb in every brand (1.7–5.2 × 10⁻⁵, i.e., one-to-two orders of magnitude above tolerable).

Methods (brief)

Ten (10) samples of each of three commercial brands of canned energy drink were purchased from retail outlets in Birnin Kebbi, Kebbi State, Northwestern Nigeria every other week during March–April 2021, across four field-sampling weeks, yielding 120 samples total (40 samples per brand). Batch numbers differed between sampling weeks. Samples were stored under retail-shop-equivalent conditions prior to analysis.

For analysis, 15 mL of each beverage sample was added to 15 mL of distilled water and 15 mL of concentrated nitric acid in a beaker. The mixture was heated gently to reduce the total volume to approximately 15 mL until red fumes indicating nitric-acid release were observed. The digest was filtered into a clean beaker, brought to 50 mL with distilled water, and analysed for Zn, Cd, Pb, Cu, and Fe using a PG-990 atomic absorption spectrophotometer (AAS). The source attributes the digestion protocol to Yahaya & Okpuzor (2012).

Quality assurance and control: glassware and plasticware were washed with detergent and rinsed with deionised water, sterilised with 10% nitric acid, and rinsed again. Background contamination was checked by analysing blank samples after every five sample analyses. All analyses were performed in triplicate; reproducibility was reported at the 95% confidence level. All chemicals were of analytical grade. The source does not report limits of detection or limits of quantification, certified-reference-material recovery percentages, blank-correction values, or instrument-method validation metrics.

Health-risk inputs (Tables 1–4): ADI and HQ used IR = 0.5 L/day, EF = 365 days/year, ED = 30 years, BWT = 65 kg, AT = 4 680 days. CR used IR = 2.0 L/day, ED = 70 years, AT = 25 550 days; same body weight. Oral reference doses (mg L⁻¹ day⁻¹)⁻¹ were Zn 0.30, Cu 0.0371, Pb 0.001, Fe 0.7, Cd 0.0005 (Iwuanyanwu & Chioma 2017). Cancer slope factors (mg kg⁻¹ day⁻¹)⁻¹ were Pb 0.0085 and Cd 6.3 (Masok et al. 2017); Zn, Cu, and Fe were treated as non-carcinogenic (CSF = 0).

Statistical reporting: per-brand values are reported as mean ± standard deviation across the n=40 samples per brand. The source does not present per-sampling-week values or per-batch values; the per-brand summary is the only level at which the underlying sample-level data appear in the publication. The source does not report a between-brand statistical comparison (no ANOVA, no Kruskal-Wallis).

The arsenic analyte and the mercury analyte were not measured. The chromium analyte was not measured. No speciation was performed (the inorganic arsenic (iAs)/total arsenic (tAs) and methylmercury (MeHg)/total mercury (tHg) distinctions are not applicable because neither arsenic nor mercury was in the panel). Among the ten HMTc/HMI analyte slots, this source covers Pb, Cd, and (incidentally) the non-HMTc analytes Zn, Cu, and Fe — three of ten HMTc analytes are addressed (Pb, Cd; the source’s Zn-Cu-Fe panel does not overlap the rest of the HMTc analyte list). MeHg/tHg, tAs/iAs, nickel (Ni), aluminum (Al), hexavalent chromium (Cr-VI), tin (Sn), and uranium (U) are not addressed.

Evidence Fitness

This source is direct primary occurrence evidence for finished canned energy drinks measured in Nigeria in 2021–2022. The analytical methodology — concentrated nitric-acid wet digestion followed by AAS — is method-appropriate for the matrix analysed, but several characteristics constrain pooling eligibility and synthesis weight:

(i) No analytical quality control reported. The source does not report limits of detection (LOD), limits of quantification (LOQ), certified-reference-material (CRM) recovery percentages, blank-correction values, or instrument-method validation metrics. Triplicate analysis and 95% confidence-level reproducibility are stated in prose but the underlying reproducibility data are not tabulated. Analytical accuracy cannot be independently verified from the published article.

(ii) Per-brand mean only; no per-sample distribution. The source aggregates n=40 samples per brand into a single mean ± SD, with no per-sampling-week, per-batch, or per-sample tabular breakout. The within-brand standard deviations reported in Table 5 (0.00–0.0058 mg L⁻¹) are implausibly small for forty samples drawn from four sampling weeks across two months, particularly given that batch numbers differed between sampling weeks. Without per-sample data, the underlying distribution for any of the three brands cannot be inspected, and the pooling for percentile-based standards is limited to a single point per brand rather than forty.

(iii) Brand-level reporting in violation of HMI public-wiki Part 12. The source publishes per-brand contamination tables that name three commercial brands and rank them. (strict reading locked 2026-05-17) prohibits reproducing such brand-level tables in the public wiki. This wiki page anonymises the brand identifiers as Brand A, Brand B, and Brand C and treats the source as a three-sample dataset of canned-energy-drink brand-level means from the Nigerian market.

(iv) Reference-value framework is drinking-water, not beverage-specific. The cited WHO 2014 permissible limits (Zn 5.00, Cu 0.05, Pb 0.01, Fe 0.1, Cd 0.02 mg L⁻¹) are WHO drinking-water guideline values. There is no matrix-specific contaminant limit for energy drinks in Nigerian or international regulation at the time of the source’s writing; the source applies the drinking-water cap as a proxy comparator. The “exceedance” findings are exceedances of a drinking-water cap applied to a non-drinking-water matrix, not of a regulatorily binding energy-drink limit.

(v) Several reported concentrations are at the extreme high end of published energy-drink ranges. Brand A’s Cu value (14.041 mg L⁻¹) is approximately 280-fold above the cited WHO drinking-water limit and is approximately two-to-three orders of magnitude above the per-sample Cu values reported in the companion Hamza et al. 2025/2026 and Babayo et al. 2026 Nigerian energy-drink papers, which sample non-overlapping brand panels in the same national market. The three Cd values (0.769–0.779 mg L⁻¹) and the three Fe values (1.083–1.157 mg L⁻¹) are likewise high relative to the comparator literature. The values are reported here as the source presents them; whether they reflect a genuine three-brand outlier signal or an analytical-method artefact cannot be determined from the published article in the absence of LOD/CRM-recovery reporting (item (i)) and per-sample distribution (item (ii)).

(vi) The ADI Table 6 units label is mg L⁻¹, but the equation as written and the standard ADI calculation produce a result in mg kg⁻¹ day⁻¹. The numerical values in Table 6 (0.014–0.252) are consistent with mg kg⁻¹ day⁻¹ as the unit and inconsistent with mg L⁻¹ as the unit (spot-check: Cd in Brand A = 0.779 × 0.5 × 365 × 30 / (65 × 4 680) = 0.014 mg kg⁻¹ day⁻¹, matches Table 6; the same recomputation gives 0.014 mg L⁻¹ only if the formula is misapplied with the L⁻¹ unit). The same Table-6-as-mg-kg⁻¹-day⁻¹ reading is confirmed by the Table-7 HQ values (which divide ADI by the oral RfD in mg kg⁻¹ day⁻¹ to yield a dimensionless HQ). This is a paper-internal unit-labelling caveat; the substantive ADI values are reported here as the source presents them with this caveat documented in Verification notes.

(vii) Publication venue is lower-tier. African Journal of Health, Safety and Environment is a regional open-access journal published by the Applied Environmental Bioscience and Public Health Research Group at the University of Benin, Nigeria. It is peer-reviewed and CC-BY-licensed, but its citation footprint and indexing breadth are limited; the venue places an upper bound on evidence weight.

Reported public evidence label: Direct evidence — primary occurrence data for the energy-drinks matrix in the Nigerian market, with brand identities anonymised.

Evidence tier set to C. This is primary research with concrete quantitative measurements that puts it above narrative-review tier-C floor, but the absence of LOD/LOQ/CRM-recovery reporting (item i), the per-brand-mean-only sample structure (item ii), the brand-firewall anonymisation requirement (item iii), the drinking-water-cap reference framework (item iv), the analytically extreme reported concentrations (item v), the unit-label inconsistency in Table 6 (item vi), and the lower-tier publication venue (item vii) together prevent a tier-B promotion. The source contributes one Nigeria-market point per brand (n=3 brand-level means) to the broader category-level distribution and should not be relied on in isolation to set or revise any HMTc threshold.

Implications

• Certification: contributes Nigeria-market primary occurrence values for the sports-energy-drinks HMTc category (Category 5 row 9) as three brand-level mean points (n=3 brands, Brand A/B/C anonymised). Brand-level Pb means range from 0.012 to 0.323 mg L⁻¹; Cd means range from 0.769 to 0.779 mg L⁻¹; Fe means range from 1.083 to 1.157 mg L⁻¹; Zn means range from 0.937 to 1.005 mg L⁻¹; Cu means span ND to 14.041 mg L⁻¹. All values are tier-C and should not be used in isolation to set or revise an HMTc threshold; they contribute as one Nigeria-market input to the broader category-level distribution alongside the related papers in near_duplicates and higher-tier evidence such as Czarnek 2024 (Poland) and Alsayyed 2024 (Jordan).
• Courses: useful as a teaching reference for (1) the methodological hazard of comparing drinking-water reference values against a non-drinking-water beverage matrix where no matrix-specific cap exists; (2) the public-wiki brand-firewall reasoning applied to a paper that reports per-brand contamination tables; (3) the structure of HQ and CR calculation across the non-carcinogenic (HQ) and carcinogenic (CR) frameworks using USEPA exposure-factor inputs; (4) the divergence between an ADI-within-RDI finding and an HQ/CR-above-threshold finding for the same dataset (the same Cd concentration that produces a within-RDI ADI of 0.014 mg kg⁻¹ day⁻¹ produces an HQ of 26–28 and a CR of 0.088 because the carcinogenic slope factor for Cd is 6.3 (mg kg⁻¹ day⁻¹)⁻¹).
• App: contributes three brand-level mean points for the sports/energy-drinks product class in the Nigerian market; sample-level percentile work is not possible because per-sample values are not published.
• Discovery: this is the earliest dated Nigerian energy-drink occurrence paper in the existing corpus and predates the Bunu 2023 Bayelsa and Kogi studies and the Hamza 2025/2026 and Babayo 2026 Nigerian-energy-drink papers by 1–4 years. Useful comparator papers identified by the source’s own reference list that may merit ingestion if not already present: Adepoju & Ojo 2014 (energy-drink consumption among Ibadan students, Food and Nutrition Sciences), Salako et al. 2016 (alcoholic and non-alcoholic canned drinks at Idiroko border, British Journal of Applied Sciences and Technology), Magomya et al. 2015 (soft drinks in Nigeria, International Journal of Innovation Science Engineer Technology), Kilic et al. 2018 (energy drinks by ICP-MS, Environmental Monitoring and Assessment), Izah et al. 2017 (heavy metals in Nigerian beverages review, Toxics), Udota & Umoudofia 2011 (Nigerian and imported alcoholic drinks, Journal of Industrial Pollution Control), Ogunlana et al. 2015 (soft drinks in Nigeria, Journal of Global Biosciences), Ubuoh et al. 2013 (canned beers in Owerri, European International Journal of Science and Technology), Golam et al. 2021 (fizzy drinks in Dhaka, Journal of Food Science and Nutrition Research).

Provenance notes

Open-access article published in African Journal of Health, Safety and Environment (AJHSE), Volume 3, Issue 1, March 2022, pages 26–34. DOI 10.52417/ajhse.v3i1.197. Accepted 2022-03-29. Article reference number AJHSE030104. ISSN (Online) 2695-1819 / ISSN (Print) 2695-2386. Published by the Applied Environmental Bioscience and Public Health Research Group, University of Benin, Benin City, Nigeria. Licensed under Creative Commons Attribution 4.0 International (CC-BY-4.0); copyright retained by the authors. Author affiliations: Department of Biological Sciences, Department of Microbiology, Department of Biochemistry and Molecular Biology, and Department of Pure and Industrial Chemistry, Federal University Birnin Kebbi, PMB 1157, Kebbi State, Nigeria. Corresponding author Yahaya, T.O. (yahayatajudeen@gmail.com; yahaya.tajudeen@fubk.edu.ng). No funding statement, ethics statement, or conflict-of-interest declaration beyond a single “no conflict of interest” line appears in the published article. Accessed via the Manual Fetch Discovery autopilot.

Related evidence

• Lead
• Cadmium
• Zinc
• Copper
• Iron
• Sports/Energy Drinks

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.