Tajdar-oranj et al. 2018 — Pb, Cr, Cd, Al in instant noodles on the Iranian (Tehran) market with Monte Carlo non-carcinogenic risk assessment

This Tehran retail-market study reports total concentrations of lead, chromium, cadmium, and aluminium in commercial instant noodle samples drawn from three Iranian-produced brands (coded 1, 2, 3) and one imported brand (coded 4), collected in Spring 2017 and analysed by ICP-OES after acid digestion on samples dried at 85 °C for 24 h before grinding. The principal occurrence finding is that mean concentrations in every brand exceeded the WHO 0.025 mg/kg food-products ceiling for Pb, the WHO 0.003 mg/kg ceiling for Cd, the WHO 0.050 mg/kg ceiling for Cr, and the WHO 0.237 mg/kg ceiling for Al. Significant brand-vs-brand differences (Kruskal-Wallis p < 0.05) were observed for all four metals, and significant Iranian-vs-imported differences (Mann-Whitney p < 0.05) were observed for all four metals: imported noodles carried higher Cr, Cd, and Al but slightly lower Pb than the pooled Iranian noodles. The principal risk-assessment finding is that the Monte-Carlo (10 000-iteration) 95th-percentile target hazard quotient for aluminium exceeded 1 in both adult (P95 THQ_Al 1.789) and child (P95 THQ_Al 6.167) consumer panels, indicating a considerable non-carcinogenic health risk for Al from instant-noodle ingestion at the Iranian per-capita rate of 0.0027 kg/person/day; THQ for Pb, Cr, and Cd was below 1 at P95 in both panels. Children carried roughly 3.5× the adult THQ across all four metals owing to the lower-body-weight denominator.

Key numbers

Pooled per-origin mean ± SD concentrations (Abstract, p. 1; Results §“Lead in instant noodle samples” through §“Aluminum in instant noodle samples”, pp. 4-6; values in mg/kg on a dried-product basis):

Per-brand mean ± SD concentrations (Results §3.1-§3.4 prose, pp. 4-6; not all four metal values are published in the prose for every brand — gaps below are paper-internal):

Single-sample maxima and minima across the four-brand panel (Results §3.1-§3.4 prose, pp. 4-6):

The Al maximum and minimum both falling within Brand 1 is consistent with the very wide intra-brand SD (Brand 1 Al 6.83 ± 4.13 mg/kg, the highest coefficient of variation in the Al panel) and reflects sample-to-sample heterogeneity within the same commercial brand.

Reference / regulatory limits cited by the paper for direct mean-vs-ceiling comparison (Introduction §“Heavy metals introduction” and Discussion, pp. 2-3 and pp. 4-6):

The Iranian National Standard is reported to set no specific Pb limit in noodles per the paper text (“Iranian National Standard Institute established the limit of 0.15 (mg/kg) for the Pb in wheat-based food products there is no recognized standard for Pb in noodle”); the Bangladesh BSTI 2 mg/kg noodle ceiling is cited as the nearest noodle-specific regulatory comparator. The paper cites the WHO 0.050 mg/kg cereal limit as Cr-VI, not total Cr (Introduction p. 3: “The permissible limit set by WHO for chromium(VI) in cereals is 0.050 (mg/kg)”). See Verification notes for the speciation-vs-comparator mismatch this introduces.

Brand-level exceedance fractions versus WHO food-product ceilings (Conclusion p. 8):

Brand-level exceedance fractions versus Iranian National Standard / ISIRI cereal Cd ceiling (Conclusion p. 8): 40.74% of samples exceeded the ISIRI 0.03 mg/kg Cd ceiling for wheat-based food products. The Conclusion paragraph also states “Cd in 40.74% and Al in all instant noodle samples were higher than the recommended levels by Iranian Institute of Standard and Industrial Research (0.03 mg/kg) and WHO (0.237 mg/kg), for Cd and Al, respectively.” No explicit per-brand Pb-exceedance fraction against ISIRI is published (the paper notes ISIRI has no noodle-specific Pb ceiling).

Method-validation limits of detection and quantification (Results §3.1-§3.4 leading paragraphs, pp. 4-6):

ICP-OES instrumental operating conditions (Table 1, p. 3):

Exposure-assessment parameter set used in Monte-Carlo simulation (Table 2, p. 4):

Oral reference doses applied in the THQ computation (Materials and Methods §“Health risk assessment”, p. 4):

95th-percentile (P95) target hazard quotients from Monte-Carlo simulation (10 000 iterations, Oracle Crystal Ball v11.1.2.4; Results §“Health risk assessment” and Conclusion, pp. 6-8; Figs. 2-4):

The TTHQ row is wiki-computed as the sum of the four metal-specific THQ_P95 values; the paper publishes the four component THQs and Figure 4 plots a stacked bar of “TTHQ for adult and children consumers” showing TTHQ > 1 in both groups, dominated by Al. The Cr child:adult ratio of ~33 is anomalous relative to the ~3.5 ratio for the other three metals; the Cr values are at the limit of meaningful precision (Adult 7×10⁻⁶, Child 2.3×10⁻⁴) and likely reflect tail-distribution behaviour in the Monte-Carlo rather than a real ~10× elevation, but the paper does not comment on this directly. See Verification notes.

The risk-rank order in both adult and child panels was Al > Pb > Cd > Cr (Conclusion p. 7), driven by the combination of the high Al concentrations (≈ 9-16 mg/kg vs sub-mg/kg for the other three metals) and the low Al RfD (4 × 10⁻⁴ mg/kg/day vs 8.5 × 10⁻³ mg/kg/day for Pb, 5 × 10⁻⁴ mg/kg/day for Cd, and 1.5 mg/kg/day for Cr).

Methods (brief)

Sample collection. 27 Iranian-produced instant noodle samples drawn from three commercial brands (coded 1, 2, 3) and an unspecified number of imported instant noodle samples from one brand (coded 4) were collected from the Tehran retail market in Spring 2017 (Materials and methods §“Sample collection and preparation”, p. 3). The total panel size including the imported brand 4 is not explicitly published — the abstract reports “27 Iranian instant noodle samples from three commercial brands … and imported instant noodle in one brand,” and the per-brand replicate count would need to be assumed (likely 9 samples per Iranian brand × 3 brands = 27 Iranian + N imported). The wiki frontmatter sample_n: 27 records the Iranian-only count published in the abstract; the imported-brand replicate count is not stated.

Sample preparation. Instant noodle samples were dried in a hot-box oven with fan (Gallenkamp OHF097.XX1., UK) at 85 °C for 24 h, then ground with a ceramic mortar and pestle for 10 min. To prevent contact with metal surfaces, a plastic spoon was used for weighing, mixing, and collecting the powder. Powders were stored in polyethylene bags until analysis (maximum 1 week). Acid digestion was performed by combining 1 g of weighed powder with 6.0 mL of 65% HNO₃ (Merck KGaA, Darmstadt, Germany) and 2.0 mL of 30% H₂O₂ (Merck KGaA) and heating in an oven at 130 °C for 1 h. Digests were diluted to 10 mL with double-distilled deionised water, filtered through Whatman No. 42 filter paper, and re-diluted to 10 mL with double-distilled deionised water. Blank samples (6.0 mL HNO₃ + 2.0 mL H₂O₂ without any noodle aliquot) were prepared in parallel.

Instrumentation. The digested extracts were analysed by inductively coupled plasma optical emission spectrometry (ICP-OES) on a Spectro Arcos system (SPECTRO Analytical Instruments, Germany) equipped with a Flared End EOP Torch (2.5 mm). Operating conditions are tabulated above. The method follows Fathabad et al. 2018.

Quality control. One package of Iranian instant noodle was dried, ground, and split into three glassware beakers; each was acid-digested (1 g) in parallel under the same procedure, with one beaker receiving 1 mL of standard solution A, the second receiving 2 mL of standard solution B, and the third receiving no spike (solution C). Quality-control samples were injected to ICP for each heavy metal. Solutions A and B carried higher heavy-metal content than C, with B approximately double the heavy-metal content of A. The difference between the measured-vs-true content for the multielement standard (Fluka Analytical reagent no. 51844, multielement standard solution 4 for ICP) was less than 5%.

Speciation. ICP-OES on acid-digested noodle samples measures total elemental content. The paper reports Pb, Cr, Cd, and Al as total concentrations with no species separation (no Cr-VI vs Cr-III speciation step, no Al-species fractionation). The Introduction discusses Cr toxicity primarily in terms of Cr(VI) as the human carcinogen and cites the WHO 0.050 mg/kg cereal limit specifically as a Cr-VI limit, but the analytical method measures total Cr. The wiki page accordingly tags Cr as total chromium in the metals frontmatter (not Cr-VI) and flags the comparator-vs-measurand mismatch in the Verification notes.

Statistical analysis. SPSS v22.0 (SPSS Inc., USA). Differences between country origins (Iranian vs imported) were tested by Mann-Whitney U test. Differences between brands (1, 2, 3, 4 across the four-brand panel) were tested by Kruskal-Wallis H test. Significance threshold p < 0.05.

Risk assessment. Non-carcinogenic risk via the Target Hazard Quotient method (USEPA 2011):

• CDI = (C × IRi × EFi × EDi) / (BWi × ATn) — Equation 2
• THQ = CDI / RfD — Equation 1
• TTHQ = Σ THQi across metals — Equation 3

Adult and child consumer panels were modelled with the Iranian per-capita instant noodle ingestion rate of 0.0027 kg/person/day from WINA 2018. Probabilistic risk was computed by Monte-Carlo simulation (10 000 iterations) in Oracle Crystal Ball v11.1.2.4 with normal distributions assumed for C, IRi, EFi, EDi, BW, AT, and RfD. The 95th-percentile THQ was reported as the panel risk benchmark; THQ ≤ 1 indicates non-carcinogenic adverse effect is not likely, THQ > 1 indicates potentially adverse effect is likely (USEPA 2011).

Implications

This source contributes Iranian retail-market occurrence data for total Pb, Cr, Cd, and Al in commercial instant noodles drawn from three Iranian-produced brands and one imported brand on the Tehran market in Spring 2017, plus a probabilistic non-carcinogenic risk assessment under Iranian-adult (70 kg, 30 y) and Iranian-child (20 kg, 6 y) consumer assumptions. Principal contributions to the wiki evidence pool:

• A four-brand Tehran-market occurrence panel showing pooled-Iranian instant-noodle Pb 1.21 ± 0.81 mg/kg, Cr 0.08 ± 0.10 mg/kg, Cd 0.03 ± 0.06 mg/kg, and Al 9.15 ± 4.82 mg/kg; imported-brand instant-noodle Pb 1.00 ± 0.61 mg/kg, Cr 0.07 ± 0.07 mg/kg, Cd 0.04 ± 0.03 mg/kg, and Al 15.90 ± 0.93 mg/kg. All four metals separated significantly between Iranian and imported origins (Mann-Whitney p < 0.05) and across the four brands (Kruskal-Wallis p < 0.05).
• A 100%-exceedance signal against the WHO 0.025 mg/kg food-products Pb ceiling: every brand’s mean Pb concentration (1.004 to 1.57 mg/kg) exceeds this ceiling by 40× to 63×. The paper notes that no Iranian noodle-specific Pb ceiling exists (ISIRI publishes a 0.15 mg/kg ceiling for wheat-based food products generally, against which all four brand means also exceed by 7× to 10×).
• A 40.74% exceedance signal against the ISIRI 0.03 mg/kg Cd cereal ceiling, driven primarily by Brand 2 (Iranian) which carries the highest Cd panel mean of 0.14 ± 0.19 mg/kg and the panel-maximum single sample of 0.35 mg/kg.
• A 100%-exceedance signal against the WHO 0.237 mg/kg food-products Al ceiling: every brand’s mean Al concentration (6.83 to 15.91 mg/kg) exceeds this ceiling by 29× to 67×. The paper attributes the Al loading to Al-containing food additives used in instant-noodle production for decorative, stabilising, firming, and anti-caking purposes (metallic Al, Al sulphates, Al silicate).
• An imported-vs-domestic origin contrast: imported instant noodles carry significantly higher Cr, Cd, and Al but slightly lower Pb than Iranian instant noodles in this Tehran-market panel. The paper recommends additional control measures specifically targeting imported instant noodles for Cr, Cd, and Al quality.
• A worked probabilistic non-carcinogenic risk assessment showing P95 THQ_Al > 1 in both adult (1.789) and child (6.167) consumer panels, identifying Al as the only metal of the four whose Tehran-market instant-noodle exposure at the Iranian per-capita ingestion rate poses a considerable non-carcinogenic risk at the 95th-percentile threshold. P95 THQs for Pb, Cr, and Cd were all below 1 in both panels under the Iranian per-capita instant-noodle ingestion rate of 0.0027 kg/person/day, indicating that despite very high concentration-vs-WHO-ceiling exceedance ratios for Pb, Cr, and Cd, the low per-capita instant-noodle ingestion rate keeps the noodle-specific health-quotient contribution below the non-carcinogenic-risk threshold for those three metals in isolation. The TTHQ sum across the four metals exceeds 1 in both panels, driven almost entirely by Al.
• A child-vs-adult risk-ratio of ~3.5× across all four metals, consistent with the body-weight ratio (70 kg adult / 20 kg child = 3.5) given the same per-capita ingestion rate. The Cr child:adult ratio of ~33 in the published P95 THQs is anomalous; see Verification notes.
• A medium-panel (27 Iranian + N imported, N not published), single-city, single-season (Tehran Spring 2017), single-cohort (Iranian adult 30 y, Iranian child 6 y) sampling footprint with no Cr-species separation, no As panel, no Hg panel, no Ni panel, no recovery / CRM / measurement-uncertainty validation data published beyond the multielement-standard <5% accuracy statement, and no per-brand replicate count published for the imported brand. The B-tier classification reflects these limitations; the source should pool with other Iranian-market noodle and wheat-based-pasta work for occurrence-distribution purposes (e.g., the Iranian per-brand mean concentration tables sit naturally in any Iranian instant-noodle dataset built alongside katyal2020-instant-noodles-canada-metals for cross-market comparison).

Wiki pages this source may touch

• lead
• chromium
• cadmium
• aluminum
• noodles
• wheat
• pasta-wheat-based

Verification notes

• Identity checks (three-way) clean. DOI grep (10.1007/s11356-018-3030-y) returned no existing wiki/sources page; raw-handle grep (MFK_tajdar-oranj2018) returned no existing page; cite-key grep (tajdar-oranj2018) returned no existing page. The page is a fresh NEW-path ingest. No first-author surname collision: no other “Tajdar-oranj” appears in wiki/sources.
• Frontmatter discipline. All ingredient, product, metal, matrix, and jurisdiction slugs verified against the 2026-05-18 taxonomy snapshot (docs/gpt-collaboration/taxonomy-snapshot.md). Metals use the Part 14 abbreviation vocabulary (Pb, Cr, Cd, Al). Matrix slug instant-noodles-dry matches the precedent set by katyal2020-instant-noodles-canada-metals. Product slug pasta-wheat-based covers the wheat-based instant-noodle product form (the paper explicitly states wheat flour is used for instant-noodle production); no rice-noodle slug is needed for this paper since all four brands are wheat-based instant noodles. Ingredient slugs noodles and wheat reflect the dual ingredient layers of the analysed product.
• Speciation discipline (Part 14, locked). ICP-OES on acid-digested noodle samples measures total elemental content; no Cr-species (Cr-VI vs Cr-III) separation step is described in §“ICP-OES analysis”. The metals: field uses Cr (total chromium), not Cr-VI. A consequential comparator-vs-measurand mismatch: the paper cites the WHO 0.050 mg/kg cereal Cr limit specifically as a Cr-VI ceiling (“The permissible limit set by WHO for chromium(VI) in cereals is 0.050 (mg/kg)”) and then compares the measured total-Cr concentrations against this Cr-VI ceiling without species correction. Since Cr-VI is typically a small fraction (<10%) of total Cr in food matrices, the paper’s “all brands exceed the WHO Cr-VI 0.050 mg/kg ceiling” conclusion is an over-call: the comparison should be against a total-Cr ceiling (e.g., the WHO Cr provisional tolerable intake or a different national total-Cr food-product ceiling) or the measured Cr should be speciated. The wiki page reports the comparator as published but flags this mismatch. No Hg panel, no As panel, no Ni panel.
• Brand firewall (Part 12, strict reading locked 2026-05-17). The paper labels its three Iranian brands “1, 2, 3” and the imported brand “4” without publishing the underlying commercial brand names. The wiki page accordingly reports per-brand statistics by the paper’s 1/2/3/4 numeric codes — these are paper-internal indexing artefacts, not real commercial brand identifiers, and reproducing them does not constitute brand attribution under Part 12. The Iranian-vs-imported origin contrast is reported per the paper’s published categorisation. Scientific-method vendor and material identifiers (Spectro Arcos / SPECTRO Analytical Instruments instrument, Gallenkamp OHF097.XX1. oven, Merck KGaA reagents, Whatman No. 42 filter paper, Oracle Crystal Ball v11.1.2.4 software, SPSS v22.0, Fluka Analytical multielement standard 51844) are retained per Part 12 Exception 2.
• Wiki/HMTc firewall (Part 2). No threshold proposals, no consumer-audience advisories. Cross-paper comparisons in the Implications section are limited to a single descriptive cross-reference to katyal2020-instant-noodles-canada-metals (Canadian-market instant-noodle Pb, As, Cd occurrence) as a candidate pooling partner for an Iranian-vs-Canadian instant-noodle market contrast in any future synthesis pass. Full cross-paper synthesis (e.g., updating the noodles or pasta-wheat-based contamination profile) is the Part 9 workflow’s job and is not done in this ingest pass.
• Sample-count opacity. The abstract states “27 Iranian instant noodle samples from three commercial brands (coded as 1, 2, and 3) and imported instant noodle in one brand (coded as 4)” but does not publish the per-brand replicate count for the Iranian brands (27 / 3 = 9 per Iranian brand, if even) or the absolute sample count for the imported brand 4. The Methods §“Sample collection and preparation” repeats the same wording without resolving the imported-brand count. The wiki sample_n: 27 records the abstract’s Iranian-panel count; total panel size including imported brand 4 is not derivable from the paper text.
• Per-brand metal table gaps. The paper publishes per-brand means and SDs for Pb (all four brands), Al (all four brands), and Cr/Cd for Iranian brands 1 and 2 only (Brand 2 Cr 0.25 ± 0.21 as the panel high, Brand 1 Cr 0.07 ± 0.07 as the panel low; Brand 2 Cd 0.14 ± 0.19 as the panel high, Brand 1 Cd 0.03 ± 0.02). Brand 3 and Brand 4 Cr and Cd per-brand means are referenced via Figure 1 but not numerically printed in the prose. The wiki Key numbers per-brand table flags these as “not stated in prose” rather than digitising the figure values by eye.
• TTHQ-sum column is wiki-computed. The Key numbers P95 THQ table includes a TTHQ row computed as the sum of the four metal-specific P95 THQ values. The paper publishes the four component P95 THQs and plots a stacked TTHQ bar in Figure 4 showing TTHQ > 1 in both adult and child panels with Al as the dominant contributor; the paper’s prose says “TTHQ of heavy metals for both adults and children was higher than 1 value (Fig. 4)” without printing the numeric TTHQ values. The wiki TTHQ row (1.811 adult, 6.246 child) is the simple sum of the four published P95 THQs and is labelled as wiki-computed.
• Cr child:adult P95 THQ ratio anomaly. The published P95 THQ_Cr for adults is 7 × 10⁻⁶ and for children is 2.3 × 10⁻⁴, a ratio of ~33×. The other three metals show child:adult P95 THQ ratios of ~3.5 (Pb 3.67, Cd 3.50, Al 3.45), consistent with the BW-ratio scaling between the two panels (70 kg / 20 kg = 3.5). The ~33 Cr ratio is anomalous and the paper does not comment on it. The most plausible explanation is Monte-Carlo tail-distribution behaviour at the very-low absolute Cr THQ values (both well below 10⁻³) where the P95 of the Cr distribution becomes sensitive to the tail of the underlying concentration distribution, which is skewed by the Brand 2 Iranian Cr 0.25 ± 0.21 mg/kg outlier. The wiki reports the published values verbatim and flags the anomaly here without re-computing the THQ.
• RfD value choice. The Pb RfD of 0.0085 mg/kg/day cited from “USEPA 2018 / PPDB 2018” is unusual relative to the more commonly used USEPA-IRIS Pb provisional oral RfD of 3.5 × 10⁻³ mg/kg/day (or the absence of a current USEPA-IRIS RfD for Pb pending the 2024-2025 reassessment). The Pb 0.0085 value matches the older PPDB (Pesticide Properties DataBase) ARfD-style value for inorganic Pb. The wiki reports the published RfD verbatim; the choice would lower the published P95 THQ_Pb by ~2× relative to a 3.5 × 10⁻³ RfD, but the qualitative finding (P95 THQ_Pb < 1 in both panels) would be unchanged.
• Basis. Per the Sample preparation procedure (§“Sample collection and preparation”, p. 3), instant noodle samples were dried at 85 °C for 24 h before grinding and acid digestion. All published concentration values are therefore on a dried-product basis. Iranian instant noodles are typically packaged dry (the noodle block plus a dry seasoning sachet); the 85 °C / 24 h pre-drying step removes residual moisture from the package-as-purchased state before digestion. The wiki matrix slug instant-noodles-dry reflects this basis. Whether the seasoning sachet was included in the analysed sample is not explicitly stated in §“Sample collection and preparation” (the published text refers to “instant noodle samples” without distinguishing noodle block from seasoning); the precedent paper katyal2020-instant-noodles-canada-metals analysed the noodle plus seasoning ground together, but Tajdar-oranj 2018 does not specify.
• Sampling-year specified. The Methods state samples were collected from the Tehran market in Spring 2017. The frontmatter sampling_year_range: "Spring 2017" records this.
• Data-integrity transcription notes. Pooled per-origin mean ± SD values transcribed from the Abstract (p. 1) and re-verified against Results §3.1-§3.4 prose (pp. 4-6). Per-brand mean ± SD values transcribed from Results §3.1-§3.4 prose (pp. 4-6); per-brand Cr and Cd values for Brands 3 and 4 are referenced in the text as part of the Figure 1 plot but not numerically printed and are not transcribed. Single-sample maxima and minima transcribed from Results §3.1-§3.4 prose. Reference limits transcribed from Introduction §“Heavy metals introduction” (pp. 2-3) and Discussion prose. LOD/LOQ values transcribed from Results §3.1-§3.4 leading paragraphs. ICP-OES operating conditions transcribed from Table 1 (p. 3). Exposure-assessment parameters transcribed from Table 2 (p. 4). RfD values transcribed from Materials and Methods §“Health risk assessment” (p. 4). P95 THQ values transcribed from Conclusion (p. 7) and Figs. 2-3 (pp. 5-6). No paper-internal contradictions beyond those flagged above were identified.

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