Šmajgl & Obhođaš 2015 — Tin in disposable baby diapers, Croatia
This study quantifies total tin in the top sheet and adhesive tape system of 6 brands of disposable baby diapers (Croatia, 2012-2014) using ²⁴¹Am-excited energy-dispersive X-ray fluorescence (EDXRF). Tin appears in 4 of 6 diapers’ top sheets (range <MDL to 23.1 mg/kg) and 2 of 6 in adhesive tape systems (range <MDL to 22.4 mg/kg, with two more at 12.2 and 9.5 mg/kg). The authors note that diaper tin is almost certainly present as organotin compounds (TBT, DBT, MBT, DOT) used as PVC stabilizers, catalysts, or biocides. Measured concentrations are below the EU REACH Annex XVII No. 20 prohibition limit (0.1 % = 1000 mg/kg in articles) but exceed the voluntary EU-supplier-agreed limits of <2 mg/kg for TBT and <10 mg/kg for individual organotins, and the worst-case dermal exposure for a 6-8 month infant (5 diapers/day) is estimated at 20-100% of tolerable daily intake.
Key numbers
| Diaper # | Top sheet Sn (mg/kg) | Adhesive tape system Sn (mg/kg) |
|---|---|---|
| 1 | <MDL | 9.5 |
| 2 | 23.1 | 22.4 |
| 3 | <MDL | <MDL |
| 4 | <MDL | 12.2 |
| 5 | <MDL | n.a. |
| 6 | 2.0 | 22.4 |
- MDL (minimum detection limit): 1.5 mg/kg total Sn
- Analytical error: 15.6%
- “n.a.” = not applicable (sample not analyzed for that component)
Comparison with other diaper organotin studies (sources cited in the paper, total or speciated organotin where reported):
| Product layer | Reported organotin (mg/kg) | Source |
|---|---|---|
| Nappies/diapers | 0.023 | WHO 2006 |
| Nappies/diapers | 0.049 | WHO 2006 |
| Nappies/diapers | 0.019 | WHO 2006 |
| Nappies/diapers | 0.024 | WHO 2006 |
| Nappies/diapers tape system | 47 | WEN 2000 (Women’s Environmental Network) |
| Nappies/diapers polyester covers | 33.7 | Kannan & Kurunthachalam 1999 |
| Nappies/diapers nylon covers | 5.5 | RIVM 2000 |
Worst-case infant dermal exposure (paper cites 6-8 month infant, 8 kg body weight, 5 diapers/day): 0.021 µg Sn/kg-bw/day; estimated 20-100% of organotin TDI (TDI value cited from RPA 2005 report). Authors flag that this exposure may be additive with other consumer-product organotin sources for children.
Regulatory references:
- EU REACH Annex XVII No. 20: prohibits organotin compounds in articles at >0.1 % by weight (>1000 mg/kg)
- Voluntary EU supplier limits: <2 mg/kg TBT; <10 mg/kg each organotin species individually (these are detection-limit-driven values, not toxicology-anchored)
- Sweden KEMI 2012 survey of 11 diaper types: no prohibited organotin found, but the same limit (0.1%) is “too high” per the authors
Methods
EDXRF using ²⁴¹Am ring-shaped radioactive source (energy 59.6 keV). Diaper top sheet and adhesive tape system separated, cut into very small pieces, homogenized, pressed into 2.5 cm pellets (~0.2 g each). Blank reference: white cotton processed identically. Standard addition with Sn certified solution (1 g/L, TraceCERT, Fluka). Canberra Ge(Li) detector (GL0055P, FWHM 155 eV at 5.9 keV), 2000 s acquisition. IAEA AXIL + QXAS software for spectrum fitting.
EDXRF measures total Sn. It does NOT speciate organotin compounds (TBT, DBT, MBT, DOT). For speciation, the authors note that gas chromatography (GC) or liquid chromatography (LC) with ICP-MS or AAS is required; those methods have lower LODs (µg/g to ng/g) but require destructive extraction, derivatization, and have lower sample-volume throughput than EDXRF.
Implications
Certification: For HMTc Cat 2 disposable baby diapers row, this paper documents that:
- Diaper tin contamination is real and intermittent (4/6 brands in top sheet; 2/6 in adhesive tape system). Routine surveillance is justified.
- The EU REACH 0.1% prohibition limit (1000 mg/kg) is far above measured values; it doesn’t constrain real-world diaper contamination. The voluntary <2 mg/kg TBT / <10 mg/kg organotin limits are operative.
- Speciation matters: total Sn by EDXRF is fast and cheap (3-day throughput per ~$X capex) but doesn’t separate inorganic Sn (low toxicity) from organotins (TBT, DBT, MBT, DOT — neurotoxic, reproductive, endocrine-disrupting). HMTc Cat 2 diaper thresholds should require organotin speciation in addition to total Sn.
- Worst-case dermal exposure for an 8 kg infant on 5 diapers/day reaches 20-100 % of TDI. This is the highest single-product Sn exposure for the youngest age group and warrants a precautionary threshold below 2 mg/kg total Sn in any diaper layer with skin contact.
Courses: Useful for a Cat 2 module on dermal exposure modelling. The 20-100 % TDI estimate is a teachable example of how an exposure surface (diaper) × frequency × duration × dermal absorption fraction × body weight calculates to a real dose.
App: For diapers, the consumer app should flag high-Sn brands (any layer >10 mg/kg total Sn) as concerning. Speciated organotin data is rarely on labels; the surrogate “total Sn” from supplier COAs is the practical proxy.
Microbiome: Not addressed in this paper. Organotin effects on the developing gut microbiome (relevant for infants whose gut is colonizing) are documented elsewhere; cross-reference microbiome when those source pages exist.
Wiki pages updated on ingest
- tin
- organotins (if exists; otherwise propose new metal page for speciated Sn)
- disposable-baby-diapers (Cat 2 row — to be created)
- children-personal-care
- eu-reach-annex-xvii-no-20-organotins (to be created)