Toxic metal contamination and health risk assessment of packaged fruit juices for children in Gondar city, Ethiopia

Overview

This peer-reviewed Scientific Reports study (Sci Rep 15:36868, 2025) measured cadmium, chromium, lead, and nickel in 80 packaged fruit juice samples consumed by children in Gondar city, Northwest Ethiopia. Samples covered eight Ethiopian-manufactured brands across four juice types (mango, pineapple, strawberry, cocktail) and five packaging formats (tetra pack, glass, carton, plastic, canned). Health risk to children aged 3-14 years was assessed via target hazard quotient (THQ), hazard index (HI), and cancer risk (CR), parameterized from a separately-conducted consumption survey of n=422 Gondar children. Median pooled concentrations across all 80 samples were cadmium (Cd) 0.08 mg/L, chromium (Cr) 0.004 mg/L, lead (Pb) 0.035 mg/L, nickel (Ni) 0.078 mg/L (Table 5). Several samples exceeded international safety limits for Cd, Ni, and Pb, but all individual-metal THQ values and HI fell below 1, suggesting non-cancer effects are unlikely at the modeled intake (0.034 L/day, 20 kg body weight, 6-year exposure duration). Cancer risk for Cd and Ni exceeded the USEPA 1×10⁻⁶ acceptable threshold. Cr and Ni concentrations differed significantly by juice type (Kruskal-Wallis p=0.018 for Cr, p=0.001 for Ni; Cd p=0.055 is at the conventional threshold but does not meet p<0.05); the authors also report that juices in cans and glass containers carried higher metal loads than tetra pack or plastic containers. Method: 210VGP flame atomic absorption spectroscopy with HNO₃ wet acid digestion, triplicate measurements, certified reference material from an India-accredited laboratory, calibration r² 0.9983-0.9998 (Table 2; the PDF narrative text on p. 3 prints the range as 0.9983-0.9992, a paper-internal inconsistency).

Key numbers

Pooled medians and ranges across all 80 samples (Table 5, unspiked column; mg/L)

Metal	Median ± IQR	Min	Max	ppb-equivalent of median
cadmium (Cd)	0.08 ± 0.026	0.010	0.1	80 ppb
chromium (Cr)	0.004 ± 0.002	0.0003	0.0081	4 ppb
lead (Pb)	0.035 ± 0.0022	0.01	0.04	35 ppb
nickel (Ni)	0.078 ± 0.035	0.0025	0.08	78 ppb

Ni and Cd medians lie close to the reported maxima for the 80-sample set; this is unusual for a median statistic but reflects what the source publishes in Table 5.

Median by juice type (Table 6; mg/L)

Metal	Mango (n=50)	Pineapple (n=10)	Strawberry (n=10)	Cocktail (n=10)	Kruskal-Wallis p
cadmium (Cd)	0.056	0.06	0.08	0.07	0.055
chromium (Cr)	0.004	0.0051	0.0036	0.0031	0.018*
lead (Pb)	0.031	0.0315	0.0353	0.036	0.68
nickel (Ni)	0.034	0.07	0.062	0.0565	0.001*

*p < 0.05. The source’s Table 6 prints “Pub” in the row that holds Pb values; this is a typographical error in the source and the row is lead.

Health risk assessment for children (Table 7)

Metal	CDI (mg/kg/day)	THQ	CR
cadmium (Cd)	5.1×10⁻⁴	0.136	1.55×10⁻⁵
chromium (Cr)	4.13×10⁻⁵	2.26×10⁻⁴	1.02×10⁻⁶
lead (Pb)	2.04×10⁻⁴	0.017	1.56×10⁻⁷
nickel (Ni)	4.08×10⁻⁴	0.0165	6.76×10⁻⁵

Hazard Index (HI = ΣTHQ) = 0.171. All single-metal THQ values are below 1 and the HI is below 1, indicating non-cancer adverse effects are considered unlikely at the modeled intake. Cancer risk ranking is Ni > Cd > Cr > Pb. Cd (1.55×10⁻⁵) and Ni (6.76×10⁻⁵) exceed the USEPA 1×10⁻⁶ acceptable cancer-risk threshold; Cr (1.02×10⁻⁶) is at the threshold; Pb (1.56×10⁻⁷) is below.

Exposure parameters (source p. 5): ingestion rate IRi = 0.034 L/day (converted from 0.238 L/week as stated in the methods text; the Table 4 survey mean of 0.28 L/week ± 0.095 was not used directly in the HRA model); body weight BWi = 20 kg; exposure duration ED = 6 years; exposure frequency EF = 365 d/yr; averaging time AT = ED × EF = 2190 days; age-dependent adjustment factor ADAF = 3 for cancer risk. Reference doses (RfD, mg/kg-day): Cd 0.001, Cr 0.003, Pb 0.0035, Ni 0.008. Cancer slope factors (kg-day/mg): Cd 0.38, Cr 0.5, Pb 0.0085, Ni 1.7.

Analytical performance (Table 3, with caveat below)

Metal	Recovery (%)	RSD (%)	Column-3 “LOQ” (mg/L)	Column-4 “LOD” (mg/L)
cadmium (Cd)	81.5-113.3	1.2-13	0.01	0.04
chromium (Cr)	99.9-113	1.4-13.3	0.02	0.0024
lead (Pb)	100-114.5	2.17-13	0.04	0.08
nickel (Ni)	90-114.3	1.87-11.1	0.01	0.03

Calibration r² values: Pb 0.9998, Cd 0.9983, Cr 0.9997, Ni 0.9995 (Table 2). Table 3 columns are labeled “LOQ(mg/L)” then “LOD(mg/L)” in the source; for Cd, Pb, and Ni this produces the unusual condition LOD > LOQ. The source text (p. 4) states “Table 3 shows the instrumental detection limit ranges from 0.001 to 0.04 mg/L, whereas the method detection limit was 0.0024-0.08 mg/L,” which suggests the column labels may have been transposed or that the two columns mix instrumental and method limits. The values are reproduced here exactly as the source’s Table 3 prints them and the discrepancy is flagged in Limitations.

Methods (brief)

Sample collection: cross-sectional sampling from five purposively-selected Gondar markets (Bilko, Piassa, Chechela, College, Azezo) in 2022 (source prints the date range as “February 30 to July 30 2022”; February 30 is a non-existent date — this is a paper-internal contradiction and the actual start date is presumably an end-of-February or early-March 2022). Eight Ethiopian-manufactured brands were selected by simple random technique; 10 samples per brand were purchased proportional to lot-size, for a total of 80 juice samples. Brand identities are stated in the source as B1-B8 with associated juice and packaging descriptors (mango in tetra pack, glass, and canned formats from Neqemte; strawberry canned and pineapple carton from Addis Abeba; cocktail glass; one mango brand “B8” in plastic). Samples were transported refrigerated to the laboratory; per-brand samples were pooled and homogenized into representative composites for analysis.

Sample preparation: 4 mL aliquot of juice + 7 mL concentrated HNO₃ (69-72%) in 50 mL conical flask, heated on hotplate at 180 °C until clear and colourless; cooled digestate then diluted with 10 mL deionized water and filtered through Whatman No. 42 paper; filtrate transferred to 50 mL volumetric flask and diluted to the mark with distilled water; stored at 4 °C until analysis. Each digest analyzed in triplicate. Reagent-only blanks digested in parallel. Glassware washed with detergent and tap water, rinsed with distilled water, soaked in dilute chromic acid (H₂CrO₄ prepared from concentrated H₂SO₄), and rinsed again with distilled water.

Instrumentation: 210VGP-model flame atomic absorption spectrometer with air-acetylene flame and analyte-specific hollow-cathode lamps. Operating conditions (Table 1): Cd 228.9 nm / slit 0.7 nm / 3.244 eV; Pb 217 nm / slit 0.7 nm / 2.566 eV; Cr 359 nm / slit 0.7 nm / 3.833 eV; Ni 324.7 nm / slit 0.2 nm / 3.792 eV. Acetylene was used as the fuel gas.

Calibration and QA: seven-point calibration curves prepared from serial dilution of Blulux 1000 mg/L stock standards (range per analyte, Table 2: Pb 0.06-8 mg/L, Cd 0.005-10 mg/L, Cr 0.02-7 mg/L, Ni 0.04-6 mg/L). Certified reference material from an India-accredited laboratory was used for standard preparation. Recovery was assessed by spiking juice samples with 100 ppm Cd/Cr/Ni or 10 ppm Pb intermediate standards, redigesting, and computing %R = (C_spiked – C_sample) / C_added × 100; observed recovery 81-115% across all metals (within the 80-120% acceptance window). RSD 1.2-13.3% across metals.

Children’s juice consumption survey: a separately-conducted structured questionnaire of n=422 parents in Gondar (72.9% children age 3-6 years, 27.1% age 7-14 years; 60.6% female, 39.4% male children; mean child age 6.0 ± 2.54 years). Sample size derived from single-population proportion formula (Z=1.96, P=0.50, q=0.50, d=0.05) yielding minimum n=384; inflated to 422 for 10% expected non-response. Survey mean weekly intake 0.28 L/week ± 0.095 (range 0.25-2 L/week, Table 4). The methods text reports 0.238 L/week (= 0.034 L/day) as the value carried into the CDI calculation; this differs from the Table 4 survey mean and the page reproduces both values without resolving the discrepancy.

Statistics: data tabulated and managed in Microsoft Excel; transferred to SPSS for analysis. Non-parametric tests used because of non-normality. Kruskal-Wallis with multiple pairwise comparisons for between-group (juice-type) differences. Significance threshold p ≤ 0.05.

Limitations

The 80-sample pool mixes tetra pack, glass, carton, plastic, and canned packaging within a single statistic. Strawberry (n=10) is sampled only in canned format; pineapple (n=10) only in carton; cocktail (n=10) only in glass; mango (n=50) spans tetra pack, glass, canned, and plastic. The pooled medians in Table 5 therefore cannot be reproduced as a single packaging-homogeneous estimator. The Figures 2-4 caption/data integrity issues (see next bullet) limit how reliably the by-packaging cross-tabs can be reconstructed from the published paper alone.
Median values for Cd (0.08 mg/L, max 0.1) and Ni (0.078 mg/L, max 0.08) lie within the IQR of the reported maxima for the 80-sample set; the IQR width relative to the median-to-max distance suggests the distribution is heavily left-skewed or has ties at the upper end. The source does not publish per-sample values or the per-brand composite values, so the distribution shape cannot be independently reconstructed from the published tables.
Table 3 column labels for LOD and LOQ produce the unusual relationship LOD > LOQ for Cd, Pb, and Ni. The source’s text describes “instrumental detection limit 0.001-0.04 mg/L” and “method detection limit 0.0024-0.08 mg/L” but does not reconcile these ranges with the Table 3 column headings. Sub-LOQ imputation or non-detect handling cannot be inferred reliably from the published table alone.
Source figure labels are partially corrupted: Figures 2, 3, and 4 are each captioned “Distribution of cadmium concentration” or “Distribution of lead concentration” but the plotted y-axis ranges and values appear to correspond to different analytes in the surrounding text (Fig. 2’s body-text refers to chromium; Fig. 3’s body-text refers to lead; Fig. 4’s body-text refers to nickel; Figs. 3 and 4 are visually identical to each other). Because of these caption/data mismatches, the figure-level packaging × juice-type cross-tabs are not reproduced on this page; Tables 5 and 6 are used as the reliable cross-tabs.
Sampling date range is stated as “February 30 to July 30 2022,” a paper-internal contradiction (February has no 30th day).
The HRA intake parameter (0.238 L/week → 0.034 L/day) used in the CDI calculation differs from the survey-derived mean intake (0.28 L/week, Table 4). The source does not explain the discrepancy.
Only Ethiopian-manufactured brands were included; the conclusion does not generalize to imported juices on the Ethiopian retail market.
The CSF (cancer slope factor) values used (Cd 0.38, Cr 0.5, Pb 0.0085, Ni 1.7 (kg-day/mg)) are stated by the authors without IRIS/USEPA citation; the Cr CSF in particular (0.5) corresponds approximately to the oral CSF for Cr(VI), not total Cr — the source measures total Cr by FAAS and does not speciate, so the CR estimate for Cr should be treated as an upper bound assuming all Cr is Cr(VI).

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