Investigation of the concentration of chemical compounds in toys

Overview

This single-author peer-reviewed study in the first issue of Environmental Health and Pollution Research surveys 120 children’s toys (30 each of plastic, painted wood, rubber, and plush) sampled across three Iranian cities in January–June 2024 for five heavy metals (Pb, cadmium (Cd), total mercury (tHg), total arsenic (tAs), Cr) by ICP-MS and for phthalate plasticizers (DEHP, DBP, BBP), bisphenol A, and brominated flame retardants (PBDEs) by GC-MS. The principal heavy-metal findings are that painted-wood toys carried the highest mean concentrations of lead (Pb) (212.4 ± 45.1 mg/kg), chromium (Cr) (102.3 ± 25.7 mg/kg), and mercury (Hg) (4.5 ± 1.4 mg/kg), with painted-wood Cr and Hg group means exceeding the EU EN-71-3 reference values cited in the same tables (60 and 2 mg/kg, respectively) and the painted-wood Pb mean approaching but not exceeding the cited 160 mg/kg Pb reference. Plush toys consistently exhibited the lowest mean concentrations across all five metals. Stated non-compliance rates were 23.3% (Pb), 30.0% (Cr), and 6.7% (Hg) in the painted-wood subset; the paper reports 0% non-compliance in the plastic subset for any heavy metal. Kruskal-Wallis testing returned p = 0.003 for Pb (painted wood > plastic, rubber, plush; plastic > plush) and p = 0.057 for Cd (no significant pairwise differences). The author concludes that painted-wood toys present the highest heavy-metal exposure risk in the Iranian retail market and calls for the Institute of Standards and Industrial Research of Iran (ISIRI) to strengthen enforcement of ISIRI 6243 and ISIRI 10166 on rubber and painted-wood toys.

Key numbers

All concentrations are reported in mg/kg as group mean ± SD (n = 30 per material category). The paper describes two sample-preparation protocols — (a) EN-71-3 simulated-gastric acid extraction (0.07 mol/L HCl, 2 h at 37 °C) for migratable elements, and (b) closed-vessel microwave-assisted HNO₃/H₂O₂ digestion of 0.5 g material for total elemental analysis — but does not state which protocol produced the Table 1 values, and the body text characterises the Table 1 values against “EU migration limits” (the EN-71-3 framing) without disambiguating. Both extractables and total-content interpretations are textually supported; this ambiguity is documented in Verification notes.

Heavy-metal concentrations by toy material (Table 1, p. 44; n = 30 per category; mg/kg, mean ± SD)

Body-text emphasis (p. 45): painted-wood toys exhibited the highest mean Pb (212.4 ± 45.1 mg/kg) and Cr (102.3 ± 25.7 mg/kg), “both exceeding the EU migration limits (160 mg/kg for lead and 60 mg/kg for chromium)”; mercury “also surpassed its limit (2 mg/kg) in some painted wooden samples.” Plastic toys “contained significant amounts of lead (145.2 ± 38.6 mg/kg) and chromium (85.6 ± 20.4 mg/kg), but their average lead content remained within the EU limit.” Plush toys “consistently demonstrated the lowest concentrations across all tested heavy metals.”

Regulatory non-compliance rates (Table 3, p. 46; samples exceeding cited EU limits)

Statistical comparison across material categories (Table 4, p. 46; Kruskal-Wallis with Dunn’s post-hoc, Bonferroni-corrected)

Organic-compound concentrations by toy material (Table 2, p. 45; n = 30 per category; mg/kg, mean ± SD)

Reported for context — these are not heavy-metal data but support the paper’s overall material-stratification finding.

Hazard-quotient summary

The paper states (Conclusion, p. 47) that “Quantitative health risk assessment confirmed these concerns, calculating Hazard Quotients (HQ) exceeding 1 for lead in painted wood toys and DEHP in rubber toys, indicating a potential for adverse health effects under reasonable exposure scenarios.” Numerical HQ values, the exposure-parameter inputs used, and the reference doses applied are not tabulated; the HQ > 1 conclusion is stated only as a qualitative summary.

Methods (brief)

Sampling (Section 2.1, p. 44). Stratified random sampling of 120 children’s toys from major retail chains, toy stores, online marketplaces, and informal vendors/bazaars in Tehran, Shiraz, and Tabriz between January 2024 and June 2024. Four material strata (plastic, painted wood, rubber, plush) with n = 30 per stratum. Inclusion criteria: newly purchased; explicitly marketed for children under 12; prioritizing mouthing or prolonged-skin-contact items (teethers, dolls, squeeze toys, building blocks). Exclusion criteria: “phthalate-free” or “BPA-free” labels; educational/scientific kits not intended for routine play.

Sample preparation (Section 2.3, p. 44). Two protocols applied to each sample: (a) EN-71-3 acid extraction — sample immersion in 0.07 mol/L HCl for 2 h at 37 °C to simulate gastric conditions and assess migratable elements; (b) microwave-assisted digestion — HNO₃ + H₂O₂ mixture applied to 0.5 g of toy material in a closed-vessel microwave system for total elemental analysis. The paper does not explicitly state which extract was used for the Table 1 mean ± SD values or for the Table 3 non-compliance rates.

Instrumental analysis (Section 2.3). Heavy metals (Pb, Cd, Hg, Cr, arsenic (As), Sb, Zn, nickel (Ni), Cu, Mn) quantified by ICP-MS; only Pb, Cd, Hg, Cr, As are tabulated. Chromium speciation (Cr(III) vs Cr(VI)) assessed by HPLC-ICP-MS; speciated Cr values are not reported in the result tables, only total Cr. Organic compounds (phthalates DEHP/DBP/BBP, bisphenol A, brominated flame retardants/PBDEs) quantified by GC-MS. The paper does not report LODs, LOQs, reference-material identifiers, or recovery percentages.

Speciation. The metals tabulated as Pb, Cr, Hg, As, Cd are total elemental concentrations from ICP-MS without speciation, despite the methods section’s mention of HPLC-ICP-MS for Cr(III)/Cr(VI). No inorganic arsenic (iAs)/tAs distinction; no methylmercury (MeHg)/tHg distinction. The source metadata records this as metals: [Pb, Cd, tHg, tAs, Cr] (when a paper does not separate iAs vs tAs the page uses tAs; when it does not separate MeHg vs tHg it uses tHg; when total Cr without hexavalent chromium (Cr-VI) it uses Cr).

Statistical analysis (Section 2.4, p. 44). SPSS v26. Descriptive statistics (mean, SD, range) per compound × material. Normality assessed by Kolmogorov-Smirnov. For non-normally distributed data, Mann-Whitney U and Kruskal-Wallis tests across material categories. Post-hoc pairwise testing by Dunn’s test with Bonferroni correction. Principal Component Analysis (PCA) “employed to identify clustering patterns and potential sources of contamination” — PCA results are not reported in the manuscript. Significance set at p < 0.05.

Authorship. Single author: Mehran Seifi, Student Research Committee, Research Institute for Health Development, Kurdistan University of Medical Sciences, Sanandaj, Iran. Corresponding author email mehran.seifi72@gmail.com on the title page. Received 20 October 2025; revised 01 January 2026; accepted 01 January 2026; published 02 January 2026. AI Use Declaration: ChatGPT used for language translation; the author retains full responsibility for the manuscript content.

Implications

• Direction of finding (HMTc Cat 21 routing). The paper’s material-stratified design reproduces a pattern reported in the toy-contamination literature corpus: painted-wood toys carry higher Pb/Cr exposure risk than plush, plastic, or rubber toys; rubber toys carry higher phthalate-plasticizer exposure risk than plush, painted-wood, or plastic toys; plush toys consistently exhibit the lowest chemical burden across analyte panels. For HMTc Cat 21 (Children’s Toys, Arts, and Crafts) Row 1 (toys-painted, general toys with paint/surface coatings), Row 6 (toys-squeeze), and Row 3 (toys-stuffed-bean-bag), this paper contributes direction-of-finding evidence for the material-stratification approach, with the caveat that the absolute point estimates carry the data-integrity uncertainty documented in Verification notes (mean ± SD vs reported non-compliance rates not internally consistent under a normal-distribution assumption).

• Iranian retail-market baseline. This is one of a small number of corpus sources reporting heavy-metal contamination in children’s toys in the Iranian retail market (Tehran, Shiraz, Tabriz, 2024). The paper’s sampling frame deliberately spans formal channels (retail chains, toy stores), online marketplaces, and informal channels (street/bazaar vendors), making the dataset informative for the import-and-informal-trade segment of the Iranian children’s-toy market that is harder to surveil through customs-only data.

• App. Per-material-category mean ± SD distributions for Pb, Cd, tHg, tAs, Cr in painted-wood, plastic, rubber, and plush toys are direct input for any future app feature estimating contamination likelihood by toy material. The Cd group means range 7.8–9.1 mg/kg across the three non-plush categories (with no significant pairwise differences by Kruskal-Wallis, p = 0.057) and 1.2 mg/kg for plush — a useful background-Cd-floor data point for the Cat 21 baseline.

• Courses. Worked example for (a) the EN-71-3 simulated-gastric acid-extraction protocol vs total-elemental microwave digestion, and the EN-71-3 limits’ migration-vs-total-content framing that the paper itself does not disambiguate; (b) the limits of group-mean comparison against migration limits when non-compliance is the regulatory test (the paper reports group means alongside non-compliance rates without reconciling the two when mean ± 1 SD straddles the limit); (c) Kruskal-Wallis + Dunn’s with Bonferroni as the non-parametric workhorse for material-stratified contamination surveys when the Kolmogorov-Smirnov test rejects normality. The paper-internal data-integrity inconsistencies (see Verification notes) make this a useful teaching case for the broader question of how a wiki source page handles a peer-reviewed paper whose internal arithmetic does not fully reconcile.

• Microbiome. Not addressed by this source.

Related evidence

• Lead
• Chromium
• Mercury
• Arsenic
• Cadmium
• General toys with paint/surface coatings
• Squeeze toys
• Stuffed toys and bean bag-type toys
• Pacifiers and sucking/teething aids

Update history

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