Nutritional Risks of Heavy Metals in the Human Diet—Multi-Elemental Analysis of Energy Drinks

Overview

Czarnek and colleagues (John Paul II Catholic University of Lublin; Medical University of Lublin; Maria Curie-Skłodowska University; Jagiellonian University; Lublin University of Technology; University of Life Sciences Lublin; Yeditepe University, Istanbul) quantified four macro-minerals (Na, K, Mg, Ca) and fifteen micro-minerals (B, aluminum (Al), V, chromium (Cr), Mn, Fe, Co, nickel (Ni), Cu, Zn, arsenic (As), Sr, cadmium (Cd), Ba, Pb) in nine commercially available energy-drink brands sold in Poland, all packaged in aluminum cans. Macro-minerals were measured by ICP-OES (Varian 720-ES) and micro-minerals by ICP-MS (Agilent Technologies 7700x), with each brand sampled in triplicate after microwave-assisted nitric-acid digestion. A toxicological risk assessment computed estimated daily intake (EDI), hazard quotients (HQ), cumulative hazard index (HI), and incremental lifetime cancer risk (ILCR) for adolescents (10–18 years, body weight 45 kg, intake 0.23 L/day) and adults (18–65 years, body weight 70 kg, intake 0.16 L/day). All HQ and HI values remained below the threshold of 1 for both age groups, but ILCR values for As, Cr, and Ni exceeded the 10⁻⁶ safe limit in multiple samples, with one sample (ED7) crossing the 10⁻⁴ high-cancer-risk threshold for arsenic in adolescents. The authors state this is the only study to date that has estimated carcinogenic risk from toxic-element exposure via energy-drink consumption.

Key numbers

All concentrations are reported in the source as mg L⁻¹ for macro-minerals and µg L⁻¹ for micro-minerals, based on n=3 replicate measurements per energy drink (total n=27 measurements per analyte across the nine brands). Statistical analysis used R version 4.4.1 with the tidyverse and rstatix packages; the Kruskal–Wallis H test was used for non-parametric multi-group comparison and one-sample Student’s t-tests with Bonferroni corrections were used to test individual brands against WHO, EU, and US EPA drinking-water normative values.

Macro-mineral content across the nine energy drinks (Table 4, p. 6, mg L⁻¹, n=27)

Element	Min	Max	Mean	SD	p.adj (Bonferroni)
Sodium (Na)	8.62	619.85	377.16	223.25	0.00524
Potassium (K)	5.51	189.57	65.28	72.90	0.00552
Magnesium (Mg)	0.013	543.97	83.96	184.14	0.00476
Calcium (Ca)	2.54	116.1	23.15	35.66	0.00692

Magnesium showed the largest spread (0.013–543.97 mg L⁻¹), driven by ED9 which is enriched with this element at the production stage (543.97 mg L⁻¹) against a background of low single-digit values in other drinks.

Micro-mineral content across the nine energy drinks (Table 5, p. 6–7, µg L⁻¹, n=27)

Element	Min	Max	Mean	SD	p.adj	WHO drinking-water limit (µg L⁻¹)	EU drinking-water limit (µg L⁻¹)	US EPA drinking-water limit (µg L⁻¹)
Boron (B)	194.01	796.82	432.28	186.54	1.00000	2400	1500	1400
Aluminum (Al)	227.54	456.97	297.32	67.18	0.43800	N/A	200	200
Vanadium (V)	0.29	10.44	3.60	3.04	0.02640	N/A	N/A	N/A **
Chromium (Cr)	13.49	67.53	39.70	18.26	0.02520	50	50	100
Manganese (Mn)	6.69	107.27	27.38	35.27	0.05415	N/A	50	50
Iron (Fe)	121.86	308.31	205.34	66.00	0.22950	300	200	300
Cobalt (Co)	0.19	4.13	1.20	1.18	0.01830	N/A	N/A	100
Nickel (Ni)	2.04	6.57	3.36	1.57	0.14745	70	20	100
Copper (Cu)	2.94	16.76	8.02	4.31	0.02950	2000	2000	1300
Zinc (Zn)	10.34	64.56	23.98	17.27	0.03960	N/A	N/A	5000
Arsenic (As)	1.57	23.05	7.33	7.00	0.02625	10	10	10
Strontium (Sr)	2.99	3878.21	452.74	1284.72	0.02400	N/A	N/A	1500
Cadmium (Cd)	0.19	0.78	0.34	0.18	1.00000	3	5	5
Barium (Ba)	4.81	19.98	11.54	5.18	0.04095	1300	N/A	2000
Lead (Pb)	5.00	32.79	10.37	8.53	1.00000	10	10	15

** A proposed notification level for vanadium of 15 µg L⁻¹ in drinking water established by the OEHHA (California). p.adj are p-values after Bonferroni correction.

Per-brand medians for the toxic elements (Figures 1–6, p. 8–10, µg L⁻¹, n=3 per brand)

Brand	Al median	As median	Cd median	Cr median	Ni median	Pb median
ED1	423.580	1.530	0.770	34.538	5.292	8.030
ED2	225.960	4.180	0.410	27.806	2.756	8.390
ED3	300.510	4.110	0.250	61.851	6.530	32.670
ED4	201.220	2.450	0.266	57.366	2.395	8.470
ED5	227.350	3.350	0.330	35.590	2.960	9.630
ED6	301.080	3.751	0.180	30.890	2.820	9.420
ED7	268.150	23.010	0.188	13.290	2.310	7.290
ED8	273.960	12.560	0.350	29.502	3.430	6.450
ED9	290.150	10.730	0.240	67.560	1.990	4.980

The notable exceedances called out by the authors (p. 14–17) are: aluminum exceeded the EU/US EPA 200 µg L⁻¹ drinking-water cap in ED6 (statistic = 28.372, p.adj = 0.006), ED3 (statistic = 11.656, p.adj = 0.033), and ED8 (statistic = 96.162, p.adj = 0.000); arsenic exceeded the WHO/EU/US EPA 10 µg L⁻¹ cap most clearly in ED7 (median 23.010 µg L⁻¹, statistic = 30.466, p.adj = 0.005); chromium showed significant departure from WHO/EU 50 µg L⁻¹ in ED3 (statistic = 308.273, p.adj = 0.000) and a moderate exceedance in ED9 (statistic = 10.746, p.adj = 0.038); lead in ED3 (median 32.670 µg L⁻¹) exceeded the WHO/EU 10 µg L⁻¹ drinking-water reference value and the US EPA 15 µg L⁻¹ value; strontium in ED3 (3878.21 µg L⁻¹, statistic = 918.030, p.adj = 0.000) significantly exceeded the US EPA 1500 µg L⁻¹ reference; iron in ED8 deviated significantly from the EU 200 µg L⁻¹ norm (statistic = 71.735, p.adj = 0.001); manganese in ED5 (statistic = 57.898, p.adj = 0.001) and ED8 (statistic = 37.589, p.adj = 0.003) exceeded the EU/US EPA 50 µg L⁻¹ norm.

Toxicological risk assessment (Tables 6–7, p. 12–13; Table 8, p. 14)

Hazard quotients (HQ = EDI/RfD) and cumulative hazard indices (HI = ΣHQ) for adolescents (BW 45 kg, IR 0.23 L/day, EXD 8 years) and adults (BW 70 kg, IR 0.16 L/day, EXD 47 years) — both with EF = 240 days/year — using reference oral doses (mg/kg/day) of 0.2 (B), 1 (Al), 0.009 (V), 0.003 (Cr), 0.14 (Mn), 0.7 (Fe), 0.0003 (Co), 0.02 (Ni), 0.04 (Cu), 0.3 (Zn), 0.0003 (As), 0.6 (Sr), 0.0005 (Cd), 0.07 (Ba), 0.0035 lead (Pb):

Brand	Adolescent HI	Adult HI
ED1	0.10	0.04
ED2	0.10	0.04
ED3	0.23	0.10
ED4	0.12	0.05
ED5	0.12	0.05
ED6	0.10	0.04
ED7	0.32	0.13
ED8	0.19	0.08
ED9	0.24	0.10

All adolescent HI values were between 0.10 and 0.32; all adult HI values were between 0.04 and 0.13. All HI values stayed below the critical non-carcinogenic threshold of one for both age groups.

Incremental lifetime cancer risk (ILCR = EDI × CSF) for the five elements with established oral cancer slope factors — CSF (mg/kg/day) of 0.5 (Cr), 1.7 (Ni), 1.5 (inorganic As), 0.38 (Cd), 0.0085 (Pb) — across both age groups:

Brand	Cr ILCR adolescent	Ni ILCR adolescent	As ILCR adolescent	Cd ILCR adolescent	Pb ILCR adolescent	Cr ILCR adult	Ni ILCR adult	As ILCR adult	Cd ILCR adult	Pb ILCR adult
ED1	5.9 × 10⁻⁵	3.1 × 10⁻⁵	7.9 × 10⁻⁶	1.0 × 10⁻⁶	2.3 × 10⁻⁷	2.5 × 10⁻⁵	1.3 × 10⁻⁵	3.3 × 10⁻⁶	4.2 × 10⁻⁷	9.7 × 10⁻⁸
ED2	4.7 × 10⁻⁵	1.6 × 10⁻⁵	2.1 × 10⁻⁵	5.4 × 10⁻⁷	2.4 × 10⁻⁷	2.0 × 10⁻⁵	6.7 × 10⁻⁶	8.9 × 10⁻⁶	2.2 × 10⁻⁷	1.0 × 10⁻⁷
ED3	1.0 × 10⁻⁴	3.8 × 10⁻⁵	2.1 × 10⁻⁵	3.4 × 10⁻⁷	9.4 × 10⁻⁷	4.4 × 10⁻⁵	1.6 × 10⁻⁵	8.7 × 10⁻⁶	1.4 × 10⁻⁷	3.9 × 10⁻⁷
ED4	9.7 × 10⁻⁵	1.2 × 10⁻⁵	1.3 × 10⁻⁵	3.8 × 10⁻⁷	1.8 × 10⁻⁷	4.1 × 10⁻⁵	5.2 × 10⁻⁶	5.3 × 10⁻⁶	1.6 × 10⁻⁷	7.7 × 10⁻⁸
ED5	6.0 × 10⁻⁵	1.7 × 10⁻⁵	1.7 × 10⁻⁵	4.3 × 10⁻⁷	2.7 × 10⁻⁷	2.5 × 10⁻⁵	7.2 × 10⁻⁶	7.1 × 10⁻⁶	1.8 × 10⁻⁷	1.2 × 10⁻⁷
ED6	5.2 × 10⁻⁵	1.3 × 10⁻⁵	1.9 × 10⁻⁵	2.4 × 10⁻⁷	2.6 × 10⁻⁷	2.2 × 10⁻⁵	5.4 × 10⁻⁶	7.9 × 10⁻⁶	1.0 × 10⁻⁷	1.1 × 10⁻⁷
ED7	2.4 × 10⁻⁵	1.4 × 10⁻⁵	1.2 × 10⁻⁴	2.4 × 10⁻⁷	2.1 × 10⁻⁷	9.9 × 10⁻⁶	6.1 × 10⁻⁶	4.9 × 10⁻⁵	1.0 × 10⁻⁷	8.8 × 10⁻⁸
ED8	4.7 × 10⁻⁵	2.0 × 10⁻⁵	5.4 × 10⁻⁵	4.5 × 10⁻⁷	1.8 × 10⁻⁷	2.0 × 10⁻⁵	8.5 × 10⁻⁶	2.3 × 10⁻⁵	1.9 × 10⁻⁷	7.7 × 10⁻⁸
ED9	1.1 × 10⁻⁴	1.2 × 10⁻⁵	6.3 × 10⁻⁵	3.3 × 10⁻⁷	1.4 × 10⁻⁷	4.8 × 10⁻⁵	4.9 × 10⁻⁶	2.7 × 10⁻⁵	1.4 × 10⁻⁷	6.0 × 10⁻⁸

The authors interpret an ILCR < 10⁻⁶ as the safe limit, 10⁻⁶ to 10⁻⁴ as moderate cancer risk, and > 10⁻⁴ as high cancer risk (p. 5, citing refs [22,34]). On those bands: ED7 As-ILCR in adolescents (1.2 × 10⁻⁴) crosses into the high-risk band; As ILCRs for adolescents in all other brands except ED1 fall in the 10⁻⁶ to 10⁻⁴ moderate-risk band, and for adults the As ILCR is in the moderate band for ED7, ED8, and ED9; Ni ILCRs for adolescents are in the moderate-risk band across all brands; Cr ILCRs in adolescents are in the moderate band across all brands, with ED3 (1.0 × 10⁻⁴) and ED9 (1.1 × 10⁻⁴) approaching or slightly exceeding the high-risk 10⁻⁴ threshold; for adults, ED1 (1.3 × 10⁻⁵) and ED3 (1.6 × 10⁻⁵) Ni ILCRs reach the moderate band while the remainder stay below 10⁻⁶; Pb and Cd ILCRs are below 10⁻⁶ for both age groups across every sample, indicating no carcinogenic concern for these two metals in the surveyed energy drinks.

Exposure assumptions (Section 2.4, p. 4–5)

The authors compute EDI from C (metal concentration in mg L⁻¹) × IR (intake rate L/day) × EF (exposure frequency days/year) × EXD (exposure duration years), divided by BW (body weight kg) × AT (averaging time days). The numerical inputs are IR = 0.23 L/day (adolescents) and 0.16 L/day (adults); EF = 240 days/year for both; EXD = 8 years (adolescents, 10–18 years old) and 47 years (adults, 18–65 years old); BW = 45 kg (adolescents) and 70 kg (adults). The intake rate is anchored to EFSA-reported consumption patterns: adolescents (10–18 years) average ~7 L/month with at least 4–5 uses per week, adults (18–65 years) ~4.5 L/month at 4–5 uses per week.

Methods (brief)

Nine commercially available energy-drink brands were purchased from markets in Lublin, Poland; selection criteria were the most popular and widely consumed brands based on market data. All samples were packaged in aluminum cans (composition of each ED in Table 1, p. 3–4 of the source). Dissolved CO₂ was eliminated by ultrasonic-bath sonication for 70 minutes. 9 mL of the degassed sample was transferred to a Teflon cuvette with 3 mL of 65% (v/v) HNO₃ (Suprapur grade, Merck, Darmstadt, Germany), then digested in a Multiwave 5000 microwave mineralizer (Anton Paar, Graz, Austria) using a temperature-controlled program: ramp to 180 °C over 20 min, hold at 180 °C for 10 min, cool to 70 °C. Digested samples were diluted to 25 mL with ultrapure water (18.3 MΩ cm⁻¹ resistance, EASYpure™ system, Barnstead/Thermolyne, Ramsey, MN, USA). Standard calibration solutions were prepared by dilution of ICP multi-element standard solution XXV for MS (Merck, Darmstadt, Germany). All analyses were performed in triplicate (n=3 per energy drink).

Macro-minerals (Na, K, Mg, Ca) were determined by inductively coupled plasma optical emission spectrometry on a Varian 720-ES spectrometer (Varian, Melbourne, Australia) at RF power 1000 W, plasma flow 15 L min⁻¹, auxiliary flow 1.5 L min⁻¹, nebulizer flow 0.75 L min⁻¹, wavelengths Ca 396.847 nm, K 766.491 nm, Mg 279.533 nm, Na 589.592 nm.

Micro-minerals (B, Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Sr, Cd, Ba, Pb) were determined by inductively coupled plasma mass spectrometry on an Agilent Technologies 7700x series spectrometer (Agilent, Tokyo, Japan) at RF power 1600 W, plasma flow 15 L min⁻¹, carrier gas 0.34 L min⁻¹, dilution gas 0.57 L min⁻¹, MicroMist nebulizer, x-Lens ion lens, three replicate readings, 30 s stabilization, spectrum acquisition mode, 0.1 rpm nebulizer pump speed, 5 V energy discrimination. Isotopes acquired: ¹¹B, ²⁷Al, ⁵¹V, ⁵²Cr, ⁵⁵Mn, ⁵⁶Fe, ⁵⁹Co, ⁶⁰Ni, ⁶³Cu, ⁶⁶Zn, ⁷⁵As, ⁸⁸Sr, ¹¹¹Cd, ¹³⁷Ba, ²⁰⁸Pb.

Statistical analysis used R version 4.4.1 with the tidyverse suite for data manipulation and rstatix for non-parametric statistical tests. The Kruskal–Wallis H test was applied to compare element concentrations among the nine brands (multi-group comparison; n=3 per group, degrees of freedom = 8). One-sample Student’s t-tests were applied to compare each brand’s mean concentration against WHO, EU, and US EPA drinking-water normative values. Bonferroni corrections were applied to p-values to control the family-wise error rate.

The source does not report instrument-method limits of detection or limits of quantification, certified-reference-material recovery percentages, or analytical blank-correction details. The arsenic measurement is total arsenic (⁷⁵As mass) and is not speciated into inorganic and organic forms; nevertheless, the toxicological risk calculation treats the measured total As as if it were inorganic As by applying the inorganic-As cancer slope factor of 1.5 mg/kg/day (Section 2.4, p. 5). The chromium measurement is total chromium (⁵²Cr mass); the discussion explicitly notes (p. 17) that “our study measured the total Cr levels, encompassing both Cr⁶⁺ and Cr³⁺,” and that “while Cr⁶⁺ is recognized as a genotoxic and carcinogenic compound, Cr³⁺ is an essential trace element,” underscoring the need for speciation analysis to accurately assess Cr exposure risk — yet the toxicological risk calculation again applies the chromium cancer slope factor of 0.5 mg/kg/day to total Cr. Mercury and inorganic tin were not measured.

Evidence Fitness

This source is direct primary occurrence evidence for finished energy drinks measured in Poland in 2024. The analytical methodology (microwave-assisted nitric-acid digestion → ICP-OES + ICP-MS, isotope-specified mass acquisition, replicate measurements per sample, R-based non-parametric statistics with Bonferroni correction) is appropriate for the matrix and analyte panel. The principal limitations bearing on pooling eligibility and synthesis weight are: (i) sample size of nine brands × three replicates yields n=27 measurements per analyte, which gives credible per-brand medians but limits inference to the population of energy drinks more broadly; (ii) single-country single-city sampling (Lublin market, Poland) limits geographic generalisability; (iii) the source does not report limits of detection, limits of quantification, or recovery of certified reference materials, so analytical-quality control cannot be independently verified from the published article; (iv) the arsenic measurement is total As without inorganic arsenic (iAs)/total arsenic (tAs) speciation, but the cancer-risk calculation treats it as inorganic As — this overstates the cancer-risk arithmetic if the As is partially organic-bound, and the source acknowledges Cr speciation as a related caveat in its own discussion (p. 17) without revising the risk calculation; (v) all nine drinks are aluminum-can-packaged, which is the dominant Polish-market packaging and confounds the Al-from-can signal with any Al-from-ingredients signal in this dataset. Reported public evidence label: Direct evidence — primary occurrence data for the energy-drinks matrix.

Evidence tier set to B. The source is primary research, peer-reviewed (Nutrients, MDPI, IF tracked), with structured methods and reproducible statistics. Tier-A would require larger sample size, multi-region sampling, As/Cr speciation, and reported CRM recovery, none of which this study provides. Tier-C would be a narrative review with no new data; this study generates new measurements and is therefore well above tier-C.

Implications

Certification: contributes direct primary occurrence values for the sports-energy-drinks HMTc category (Category 5 row 9). Per-brand Pb medians range from 4.980 µg L⁻¹ (ED9) to 32.670 µg L⁻¹ (ED3); per-brand tAs medians range from 1.530 µg L⁻¹ (ED1) to 23.010 µg L⁻¹ (ED7); per-brand Cd medians range from 0.180 µg L⁻¹ (ED6) to 0.770 µg L⁻¹ (ED1); per-brand Cr (total) medians range from 13.290 µg L⁻¹ (ED7) to 67.560 µg L⁻¹ (ED9); per-brand Ni medians range from 1.990 µg L⁻¹ (ED9) to 6.530 µg L⁻¹ (ED3); per-brand Al medians range from 201.220 µg L⁻¹ (ED4) to 423.580 µg L⁻¹ (ED1). The Pb finding in ED3 (32.670 µg L⁻¹) exceeds the WHO/EU 10 µg L⁻¹ and US EPA 15 µg L⁻¹ drinking-water references; the tAs finding in ED7 (23.010 µg L⁻¹) exceeds all three drinking-water references (10 µg L⁻¹); these are like-for-like comparisons against drinking-water caps because no energy-drink-specific contaminants regulation governs these elements in the EU at the time of the source’s writing.
Courses: useful as a teaching reference for (1) the aluminum-can-packaging contribution to Al loading in canned beverages versus PET bottles (the discussion at p. 15 cites comparator studies showing 150–7150 µg L⁻¹ Al in aluminum cans vs 10–120 µg L⁻¹ in PET bottles); (2) the toxicological-risk methodology gap when total As is used in an inorganic-As CSF computation; (3) the chromium-speciation gap that the authors flag in their own discussion as needing follow-up; (4) the practical worked example of EDI / HQ / HI / ILCR calculation given concrete BW, IR, EXD, EF inputs.
App: contributes per-product percentile-eligible values for the sports/energy-drinks product class in the Polish market. Per-brand identities are anonymised in the source (ED1–ED9) and remain anonymised here; the contribution is to the category-level distribution, not to per-brand rankings.
Discovery: useful comparator studies referenced for downstream ingestion include Leśniewicz et al. 2016 (Polish energy and isotonic drink mineral composition, Biol. Trace Elem. Res. 170:485–495) and Kilic et al. (the source’s ref [17]) for prior Polish/regional energy-drink mineral profiles. The single rural-Cd/Pb-elevated Pb finding in ED3 (32.670 µg L⁻¹) is the dataset’s most defensible high-tail observation and should be carried forward in any future percentile-pool calculation for the energy-drinks row.

Provenance notes

Open-access article distributed under CC BY (license declaration on p. 1 of the PDF). Received 15 November 2024; revised 5 December 2024; accepted 8 December 2024; published 13 December 2024. Citation: Czarnek, K.; Tatarczak-Michalewska, M.; Wójcik, G.; Szopa, A.; Majerek, D.; Fila, K.; Hamitoglu, M.; Gogacz, M.; Blicharska, E. Nutritional Risks of Heavy Metals in the Human Diet—Multi-Elemental Analysis of Energy Drinks. Nutrients 2024, 16, 4306. https://doi.org/10.3390/nu16244306. Academic editors: Ariana Saraiva and António Raposo. Funding: “commissioned project entitled ‘The study on the impact of energy drink consumption and selected plant adaptogens on the health and mental state of young adults – a research project,’ funded by the Minister of Science and Higher Education and conducted at the John Paul II Catholic University of Lublin” (Funding statement, p. 20). Institutional Review Board: Not applicable. Informed Consent: Not applicable. Data Availability: “Data are contained within the article” (p. 20). Conflicts of interest: “The authors declare no conflicts of interest” (p. 20). Accessed via the Manual Fetch Discovery autopilot.

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