Šmajgl & Obhođaš 2015 — Tin in disposable baby diapers, Croatia

This study quantifies total tin in the top sheet and adhesive tape system of six brands of disposable baby diapers (Croatia, 2012-2014) using ²⁴¹Am-excited energy-dispersive X-ray fluorescence (EDXRF). Tin was detected in two of six diaper top sheets (range <MDL to 23.1 mg/kg) and in four of five measured adhesive tape systems (range <MDL to 22.4 mg/kg; the fifth tape system was not analyzed). The authors attribute the diaper tin to organotin compounds (TBT, DBT, MBT, DOT) used as PVC heat stabilizers, catalysts, or biocides; EDXRF reports only total Sn and cannot speciate. Measured concentrations are below the EU REACH Annex XVII No. 20 prohibition limit (0.1 % by weight = 1000 mg/kg in articles) but exceed the voluntary EU supplier-agreed limits of <2 mg/kg for TBT and <10 mg/kg for each individual organotin species. The worst-case dermal exposure scenario (6-8 month infant, 8 kg body weight, five diapers/day) is estimated at 0.021 µg Sn/kg-bw/day, equivalent to 20-100% of the tolerable daily intake.

Key numbers

Total Sn by EDXRF in six diaper brands (Table 1, p. 2):

• MDL (minimum detection limit): 1.5 mg/kg total Sn
• Experimentally determined analytical error: 15.6%
• “n.a.” = not analyzed
• Detection counts (per abstract): top sheet 2/6 (Diapers 2 and 6); adhesive tape system 4/5 measured (Diapers 1, 2, 4, 6; Diaper 5 not analyzed)

Worst-case infant dermal exposure (paper text, p. 3, citing RPA 2005 [ref 3]): 6-8 month infant, 8 kg body weight, five diapers/day → 0.021 µg Sn/kg-bw/day → 20-100% of organotin TDI. The authors note this may be additive with exposure from other consumer-product organotin sources.

Comparison values from other diaper studies (Table 2, p. 2; reported organotin cations in mg/kg, primary citations as given in the paper’s reference list):

Regulatory references cited in the paper:

• EU REACH Annex XVII No. 20: prohibits organotin compounds in articles at >0.1 % by weight (>1000 mg/kg). Also fully bans organotin biocides in antifouling paints.
• Voluntary supplier-agreed limits for non-woven polypropylene top-sheet raw material (paper ref [15], described as detection-limit-driven values rather than toxicology-anchored): <2 mg/kg TBT; <10 mg/kg each organotin species individually.
• Sediment contamination upper limits cited from refs [1,2]: 0.1-0.5 mg Sn/kg dry weight (set for sea disposal of dredged material).
• 2012 Swedish KEMI survey of 11 baby-diaper types: no prohibited organotin compounds found; the paper’s authors comment that the 0.1 % prohibition limit is “too high.”

Methods (brief)

• Instrument. EDXRF with ring-shaped ²⁴¹Am radioactive excitation source (energy line at 59.6 keV in the recorded spectra). Canberra Ge(Li) detector (model GL0055P; FWHM 155 eV at 5.9 keV). Sample-to-source distance 12 mm; samples held in 99.9% Al holder. Irradiation time 2000 s per sample.
• Sample preparation. Top sheet and adhesive tape system of each diaper separated, cut into very small pieces, homogenized, and pressed into 2.5 cm diameter pellets weighing ~0.2 g.
• Blank. White cotton processed identically to diaper samples.
• Calibration. Standard addition with Sn certified solution (1 g/L, TraceCERT, Fluka, Switzerland). Calibrating sample cut and mixed for 15 min in agate mortar before each analysis, then pelletized. Three replicate cut/mix/analyze cycles per Sn aliquot.
• Spectrum fitting. IAEA AXIL program within the QXAS software package (open-domain IAEA software).
• MDL and error. MDL = 1.5 mg/kg total Sn; experimentally determined analytical error = 15.6%.
• Speciation. None. EDXRF measures total Sn only. The paper notes that organotin speciation (TBT, DBT, MBT, DOT) requires gas chromatography (GC) or liquid chromatography (LC) coupled to atomic absorption analysis, ICP-OES, or ICP-MS, with extraction, derivatization (for GC), purification, and enrichment steps; those workflows reach µg/g to ng/g LODs but are destructive, lower-throughput, and more contamination-prone than EDXRF.

Implications

Certification: For HMTc Cat 9 Row 7 (diapers and diaper components), this paper contributes:

1. Occurrence data documenting that diaper tin contamination is intermittent across brands (2/6 top sheets, 4/5 measured tape systems above the 1.5 mg/kg MDL).
2. Confirmation that the EU REACH 0.1% prohibition limit (1000 mg/kg) is non-binding for real-world diaper contamination at the concentrations measured here; the voluntary supplier-agreed limits (<2 mg/kg TBT; <10 mg/kg each organotin species) are the operative reference levels.
3. A methodological note that total Sn (EDXRF) is a screening proxy that cannot distinguish low-toxicity inorganic Sn from neurotoxic, reproductive- and endocrine-disrupting organotins (TBT, DBT, MBT, DOT). Any certification specification that relies on total Sn alone should record this limitation; speciation by GC- or LC-coupled atomic-spectrometry methods is the orthogonal confirmation pathway.
4. A worst-case dermal exposure estimate of 0.021 µg Sn/kg-bw/day for an 8 kg infant on five diapers/day, reaching 20-100% of the cited organotin TDI under the paper’s scenario. The paper itself flags that this exposure may be additive with other consumer-product organotin sources.

Courses: Useful for a Cat 9 module on dermal exposure modelling for infant skin-contact products. The 20-100% TDI estimate is a teachable example of how exposure surface area × frequency × duration × dermal absorption fraction × body weight resolves to a tolerable-intake fraction.

App: For diapers, the consumer-app signal from this paper is “total Sn in diaper layers is intermittently present in retail product, and most consumer-facing labelling does not report it.” Speciated organotin data is rarely available outside supplier COAs; total Sn from supplier QC is the practical proxy. Because the dataset is six anonymous brands in Croatia (2012-2014), no brand-level mapping is possible.

Microbiome: Not addressed in this paper. Organotin effects on the developing gut microbiome are documented elsewhere; cross-reference microbiome when those source pages exist.

Wiki pages updated on ingest

• tin
• diapers-and-components (Cat 9 Row 7)
• children-personal-care

Verification notes

• 2026-05-18 (Claude Opus 4.7, autonomous manual-fetch v2.0 enhancement): merge-enhance pass against prior 2026-05-14 page.
  • Corrected transposed detection counts. Prior page narrative said “Tin appears in 4 of 6 diapers’ top sheets and 2 of 6 in adhesive tape system.” Paper abstract (p. 1) says the opposite: “Almost all diapers contained tin in the adhesive tape system (four of five), and two of six samples contained tin in top sheet.” Table 1 confirms: top sheet detections in Diapers 2 (23.1) and 6 (2.0) only = 2/6; tape system detections in Diapers 1 (9.5), 2 (22.4), 4 (12.2), 6 (22.4) = 4/5 measured (Diaper 5 was n.a.). The numbers were swapped between rows.
  • Corrected HMTc category assignment. Prior page assigned this to “HMTc Cat 2 disposable baby diapers row.” wiki/products/diapers-and-components.md is HMTc Cat 9 Row 7 (Infant and Child Contact Products, Ages 0-5). Cat 2 is children-personal-care, a different (broader) category. Implications section updated to Cat 9 Row 7.
  • Removed Part 5 threshold proposal. Prior page Implications #4 said “warrants a precautionary threshold below 2 mg/kg total Sn in any diaper layer with skin contact.” Per Part 5 of CLAUDE.md and the audit-prompt Check 5 boundary, source pages report occurrence data and may describe what a paper contributes to threshold work, but must not propose threshold values. Reworded to note the methodological limitation of total-Sn screening and recommend speciation as orthogonal confirmation, without proposing a numeric ceiling.
  • Corrected speciation-methods description. Prior page said “GC or LC with ICP-MS or AAS.” Paper text (p. 1) lists “atomic absorption analysis, inductively coupled plasma atomic emission spectrometry or inductively coupled plasma mass spectrometry.” Added ICP-OES to the list.
  • Fixed invalid product slug. Prior page declared products/disposable-baby-diapers as a routing target; that page does not exist in wiki/products/. Replaced with products/diapers-and-components (the existing HMTc Cat 9 Row 7 product page; matches sibling diaper sources nyamukamba2023, lai2025, bae2018).
  • Fixed matrices vocabulary. Prior page used [cosmetic-personal-care, dermal-contact-product]. Sibling diaper sources use matrices: [diaper]; aligned to that convention.
  • Fixed sample_population precision. Prior version said “Top sheet and adhesive tape system analyzed separately for total tin.” Tightened to specify EDXRF as the analytical method.
  • Removed speculative app statement. Prior page said “the consumer app should flag high-Sn brands (any layer >10 mg/kg total Sn) as concerning.” That is a threshold proposal and a brand-flag prescription. Reworded to describe what is and is not available as consumer-facing data; no numeric ceiling and no flagging-rule proposed.
  • Preserved. cite_key, raw_handle, raw_path, license, evidence_tier (A — peer-reviewed primary study in X-Ray Spectrometry), sample_n=6, jurisdictions [HR, EU].
  • Verified accurate (no change needed). All numerical values in the Key numbers table match Table 1 exactly. Methods detail (²⁴¹Am source, Canberra Ge(Li) detector model and FWHM, 2000 s acquisition, IAEA AXIL/QXAS, 2.5 cm pellet ~0.2 g, MDL 1.5 mg/kg, error 15.6%) matches paper. Exposure scenario (0.021 µg Sn/kg-bw/day, 8 kg infant, 5 diapers/day, 20-100% TDI) matches paper p. 3 exactly. Regulatory citations (REACH Annex XVII No. 20, voluntary <2 mg/kg TBT, <10 mg/kg per organotin, KEMI 2012) match.

Page history

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