Heavy Metal Index

Safety Evaluation of Absorbent Hygiene Pads: A Review on Assessment Framework and Test Methods

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Source access

Publication
Sustainability 10(11): 4146
Year
2018
Authors
Bae J; Kwon H; Kim J
Source type
peer reviewed
License
CC BY 4.0

Bae, Kwon & Kim 2018 — Safety-assessment framework review for disposable absorbent hygiene pads

This Sustainability review article describes the exposure-based quantitative risk-assessment (QRA) framework applied to disposable absorbent hygiene pads — baby diapers, feminine hygiene pads, and adult incontinence diapers — including hazard identification, hazard characterization, exposure assessment, risk characterization, clinical evaluation, and post-market surveillance. It is a methodology synthesis with no primary measurement data of its own. Heavy-metal content is limited to a regulatory listing — the Korea MFDS restriction list for baby-diaper “Sanitary Products” names eight metal contaminants (antimony, barium, cadmium, chromium, lead, mercury, arsenic, selenium) without quantitative limits or measured values — and a single secondary citation of organotin (tin) exposure from baby diapers in Šmajgl & Obhođaš 2015 (already ingested at smajgl2015-tin-baby-diapers-croatia). The paper is ingested as an out-of-core-scope methodology and regulatory-context reference; metals: [] is correct per the precedent set by lai2025-infant-diaper-phthalate-dna-oxidation (phthalate-only paper ingested for the paired diaper + urine + biomarker design). The exposure-model equations (Section 3.2.1) and the direct-contact / indirect-reflux pathway distinction (Section 3.2.2, 3.2.3) are reusable for HMI heavy-metals modeling once primary metal measurements in diaper or pad materials become available in the corpus.

Key numbers

This is a narrative review without primary measurements. The following are quantitative inputs reported by the authors as inputs to their methodology framework or as illustrative outputs from cited studies:

  • Disposable absorbent product types reviewed (Table 1, p. 3):
    • Baby diapers — age 0–36 months; time-weighted-average (TWA) body weight 10.2 kg (US EPA 2011); typical use 4.7 diapers/day (mean across all sizes, Dey et al.); length of use 36 months.
    • Feminine hygiene pads — age 14–49 years; body weight 50–60 kg; 5–7.5 pads/day; 7 days/month; ~35 years of use.
    • Adult incontinence diapers — body weight 60 kg; 2–5 pads/day (USA 3–5; Japan 3.5–4 pads or 1.5–1.75 pull-on/day per Proctor & Gamble research).
  • Korea MFDS restricted-chemical list for baby diapers (Table 2 footnote 1, p. 5): fluorescent whitening agent, formaldehyde, chlorinated phenols (pentachlorophenol and tetrachlorophenol), azoic dyes, phthalates, and heavy metals: antimony, barium, cadmium, chromium, lead, mercury, arsenic, selenium. No numerical limits are reported in this paper for the metal sub-list. For adult diapers, the MFDS list omits heavy metals (only fluorescent whitening agent, formaldehyde, pentachlorophenol, tetrachlorophenol, and azoic dyes — Table 2 footnote 2).
  • Safety regulations for diapers and sanitary pads by jurisdiction (Table 2, p. 5):
    • US — baby diapers: not available; menstrual/adult pads: FDA Class I Medical Device guidance (not legally enforceable); manufacturers recommended to identify new formulations and bleaching processes.
    • China — baby diapers and sanitary pads: GB 15979-2002 (mandatory; HS codes 9619001000 pull-up baby diapers and 9619002000 sanitary napkins/panty liners/tampons) plus GB/T 8939-2008 (guidance). Manufacturers must provide microbial and toxicological indicators (bacterial and fungal colonies, pathogenic purulent bacteria, coliforms, pH, water absorbency, infiltration capacity); imported products must report skin irritation (diapers), vaginal mucosa irritation (menstrual pads), and dermal allergic reaction (both).
    • Korea — baby and adult diapers: MFDS “Sanitary Products” (mandatory); menstrual pads: MFDS “Quasi-Drugs” (mandatory). Restricted chemicals and heavy metals as listed above; “a test protocol simulating exposure assessment has not been confirmed as of September 2018.”
  • Organotin exposure (Section 3.1, p. 7, citing ref [39] — Šmajgl & Obhođaš 2015): “Assuming the daily use of five diapers, daily organotin exposure was estimated to be 0.021 µg tin/kg weight·day. However, the dermal absorption rate of organotin compounds was not accounted in this study. Based on such information, risk characterization was conducted reporting that this content was 20–100% of the tolerable daily intake (TDI), and the risk of tin exposure is present.” Organotins listed: dibutyltin (DBT), monobutyltin (MBT), tributyltin (TBT), dioctyltin (DOT); analytical method cited as energy-dispersive X-ray fluorescence with ²⁴¹Am radioactive source.
  • Phthalate exposure example (Section 3.1, p. 7, citing ref [86]): EPA drinking-water limit for di(2-ethylhexyl)phthalate (DEHP) = 6 ppb; EPA workplace-air limit (8 h) = 10 mg/m³. European REACH and Japan regulation restrict certain phthalates in childcare articles to <0.1 % concentration (ref [87], [88]).
  • Phthalate risk characterization (Section 3.2, p. 7, citing Ishii ref [21]): seven phthalates quantified from diaper topsheet using artificial sweat and urine as eluents; extraction with dichloromethane; GC-MS analysis; transdermal absorption rate applied to compute daily exposure per body weight; Margin of Exposure (MOE) > 1000 across phthalates → tested diapers concluded safe from phthalate exposure (limitation: testing limited to topsheet only).
  • Dioxin/dioxin-like-compound exposure (Section 3.2, p. 7, citing Ishii ref [21]): polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (DL-PCBs) in fluff-pulp samples of sanitary pads; toluene extraction → GC-MS → TEQ via WHO TEFs; reference dermal absorption 3 % [ref 71,91]; estimated daily exposure < 1/9500 × TDI → risk concluded negligible.
  • VOC emission from feminine products (Section 3.2, p. 8, citing Korean MFDS ref [54]): 74 VOC types tested; pads frozen at −196 °C, ground at room temperature, analyzed at 120 °C by GC-MS; usage assumptions 7.5 pads/day, 7 menstruation days/month, lifelong use; Margin of Safety (MOS) from NOAEL (US EPA-IRIS / ATSDR / WHO IPCS) > 5 for all tested pads (likely an overestimate since the protocol assumes 100 % dermal absorption of the total VOC content of the pad).
  • Lotion / emollient transfer to skin (Section 3.2.2, p. 9): 3.0–4.3 % of the initial lotion amount transfers to skin per diaper-wearing (Odio et al. refs [36,37] using 3M Tegaderm collection-tape methodology); Rai et al. [24] alternatively used 7 % as a more conservative default skin transfer rate.
  • Indirect (fluid-reflux) exposure (Section 3.2.3, p. 9): Rai et al. [24] reflux value ≈ 0.25 % (modern SAP-containing diapers minimize resurfacing). Dey et al. controlled gravimetric collagen-skin-model study: 60 mL of 0.9 % saline applied at 82-min intervals under 0.41 psi (simulated 18–24-month-old infant pressure on 50 % diaper area) → rewetting fraction 0.32–0.66 % (mean 0.46 %). Default rewet value 0.46 % suggested as the worst-case scenario. Acrylic-acid-specific rewetting yielded 0.15–0.21 % (lower than the 0.46 % default).
  • Exposure-model equations (Section 3.2.1, p. 8):
    • Systemic exposure (µg/kg/d) = (M × C × F × D × Tdirect or indirect × A) / B
    • Dermal exposure (µg/cm²/d) = (M × C × F × D × Tdirect or indirect × A) / S
    • where M = raw-material mass in product (g); C = constituent concentration in raw material (%); F = frequency of use (numbers/day); D = exposure duration (% of day); Tdirect (%) = transfer rate from materials to skin (direct contact); Tindirect (%) = transfer rate from materials to skin (indirect contact, fluid reflux); A = dermal absorption rate (%); B = body weight (kg); S = exposed skin surface area (cm²).
  • Reference-dose conventions (Section 3.1, p. 6): No Observed Adverse Effect Level (NOAEL), Lowest Observed Adverse Effect Level (LOAEL), Oral Reference Dose (RfD), Inhalation Reference Concentration (RfC), Benchmark Dose Limit (BMDL), Acceptable Daily Intake (ADI), Tolerable Daily Intake (TDI). Uncertainty factor of 100-fold is typically used to extrapolate from animal POD to human exposure (10-fold inter-species + 10-fold inter-individual variability).

Methods (brief)

Narrative literature review, no primary samples. Structured around the four-step QRA framework (hazard identification → hazard characterization → exposure assessment → risk characterization) plus clinical evaluation and post-market surveillance, drawing on 112 cited references including OECD documents, IARC monographs, WHO IPCS, ATSDR toxicological profiles, EPA IRIS, EU REFIT and ECHA REACH lists, and primary studies of diaper and feminine-pad constituents (phthalates, organotins, dioxins, VOCs, chlorinated compounds, acrylic acid, methyldibromo glutaronitrile, cinnamaldehyde, styrene, chloromethane, chloroethane, chloroform, acetone). Regulatory frameworks reviewed: US FDA 510(k) Class I Medical Device for menstrual pads/tampons; EU consumer-product regulations (less stringent); China GB 15979-2002 (mandatory) and GB/T 8939-2008 (guidance); Korea MFDS Sanitary Products (baby/adult diapers, mandatory) and Quasi-Drugs (menstrual pads, mandatory). Exposure-model equations adapted from refs [14] (Kosemund et al.) for both systemic and dermal exposure under direct skin contact and indirect skin contact (reflux) pathways.

Implications

  • Certification (HMTc): This review contributes no occurrence values to HMTc threshold-setting for Cat 9 Row 7 (Diapers and diaper components) or Cat 15 Row 2 (Menstrual pads). It does, however, document that:
    1. Korea MFDS already regulates eight metals in baby diapers (antimony, barium, cadmium, chromium, lead, mercury, arsenic, selenium) under mandatory Sanitary Products rules, while US and EU rely on guidance or general consumer-product law and lack metals-specific limits for diapers. This regulatory gap is a HMTc-program-relevant data point: HMTc Cat 9 Row 7 thresholds will operate in a jurisdictional landscape where Korea has hard limits and US/EU do not.
    2. The exposure-based QRA framework (Section 3) is the operative methodology in this product class. Future HMI synthesis on diaper-related metals (e.g., Sn, Pb, Cd, Cr, Ni from printed-pattern dyes, SAP residuals, or backsheet pigments) should compute exposure using the direct-contact equation (Eq. 1) with conservative Tdirect = 3–7 % (lotion-transfer range) and the indirect-reflux equation (Eq. 2) with Tindirect = 0.46 % default (Dey et al. worst-case) or 0.15–0.21 % (acrylic-acid-specific range), modulated by ion-form-specific dermal absorption fraction (ABSd) from ATSDR / OEHHA guidance rather than the lipophilic-organic permeation defaults used for phthalates.
    3. The Šmajgl & Obhođaš 2015 organotin exposure estimate cited here (0.021 µg Sn/kg-bw/day → 20–100 % of TDI for a 5-diaper/day infant) is the same estimate already documented at smajgl2015-tin-baby-diapers-croatia; no independent data added.
  • Courses: Useful as a methodology reference for an HMTc educational module on dermal-exposure modelling for the diaper / pad product class. The systemic-vs-dermal exposure equations (Section 3.2.1), the direct-contact / indirect-reflux pathway distinction (Section 3.2.2, 3.2.3), and the uncertainty-factor framework (NOAEL → POD → MOE / MOS) are teaching-quality reference material. The regulatory crosswalk (Table 2) is a useful starting point for a regulatory-landscape lecture.
  • App: Not directly applicable to the heavy-metals consumer app — no per-product or per-brand metal data.
  • Microbiome: Not addressed beyond a passing mention of microbial-indicator testing under China GB 15979-2002. Out of scope for microbiome federation.

Verification notes

  • No heavy-metal occurrence data. metals: [] is correct. The paper’s only metals content is (a) a regulatory listing of eight metals in the Korea MFDS Sanitary Products restriction list (Table 2 footnote, p. 5) — names without numerical limits — and (b) a secondary citation of Šmajgl & Obhođaš 2015 organotin exposure (Section 3.1, p. 7, ref [39]) which is already ingested at smajgl2015-tin-baby-diapers-croatia with primary data. Per the lai2025-infant-diaper-phthalate-dna-oxidation precedent for diaper papers measuring only organic plasticizers, this review is ingested as out-of-core-scope methodology / regulatory-context reference rather than as a metals-occurrence contributor.
  • Brand-firewall compliance. The paper does NOT name brands as contamination-attributed entities. The “Proctor & Gamble consumer research” reference in Table 1 footnote 6 attributes adult-incontinence usage statistics (3–5 pads/day USA) to a P&G-sponsored survey cited via Rai et al. [53]; this is a use-pattern data source, not a contamination measurement, and so falls outside the Part 12 firewall. The 3M Tegaderm collection-tape product named in Section 3.2.2 (Odio et al. lotion-transfer methodology) is a scientific-method material / instrument vendor name and is preserved per the verification-checklist scientific-method exception (locked 2026-05-17).
  • Wiki/HMTc firewall (Part 2) compliance. The page reports what the review describes — frameworks, methods, regulations, cited measurements — without synthesizing claims about whether the cited measurements support tighter or looser HMTc thresholds. The Implications section names Cat 9 Row 7 and Cat 15 Row 2 as HMTc routing destinations and notes the regulatory gap (Korea has metals limits; US/EU do not) but does not propose HMTc threshold values or justify deviations.
  • Product routing. Paper covers three product classes: baby diapers, feminine hygiene pads, adult incontinence diapers. Wiki taxonomy has [[products/diapers-and-components]] (HMTc Cat 9 Row 7, infant scope) and [[products/menstrual-pads]] (HMTc Cat 15 Row 2, feminine scope). No adult-incontinence-diapers slug exists; adult incontinence is outside the HMTc Cat 9 (Ages 0-5) and Cat 15 (Feminine Care) frames covered by current taxonomy. Routing to the two available slugs captures the in-scope content; the adult-diaper coverage is documented in this page’s body but does not generate a routing row. Not surfaced as a new-page proposal because adult incontinence diapers are a deliberate scope-out under current HMTc taxonomy v2.0.
  • License. MDPI Sustainability publishes under Creative Commons Attribution (CC BY 4.0) license per MDPI’s standard open-access policy applicable at 2018 publication date. DOI 10.3390/su10114146 resolves to the open-access article at https://doi.org/10.3390/su10114146.
  • Evidence tier. Tier B — peer-reviewed methodology review with no primary measurements. Per conventions evidence grading, narrative reviews without independent data extraction sit below primary peer-reviewed studies (Tier A) but above grey literature.
  • Sample-size. sample_n: null is correct for a methodology review; the review surveys 112 references but does not constitute a defined sample frame.
  • Audit subagent (2026-05-18) flagged Check 2 ⚠️ on products/diapers-and-components and products/menstrual-pads as not present in the taxonomy snapshot. Verified against live wiki: both wiki/products/diapers-and-components.md (HMTc Cat 9 Row 7 scaffold, literature_scope: thin, frontmatter dated 2026-05-17) and wiki/products/menstrual-pads.md (HMTc Cat 15 Row 2 scaffold, literature_scope: thin, frontmatter dated 2026-05-17) exist as provisional scaffolds. Snapshot-staleness false positive — taxonomy snapshot used by the audit subagent has not yet been refreshed to include these recently-added scaffolds. Same pattern as the lai2025 and barabash2025 audits. Wiki page retains both routing destinations.

Ingest log

  • 2026-05-18 fresh ingest (Claude Opus 4.7, autonomous v2.0 manual-fetch skill, daemon tick): NEW path. Three identity checks against wiki/sources/ returned no hits: DOI 10.3390/su10114146 not present; raw_handle MFK_safety-evaluation-of-absorbent-hygiene-pads-a-revi not present; cite-key stem bae2018 not present. PDF SHA-256 1852664458af40802a0c576c35f407ee18f383bb25adc1f77a5aec9b0ad97aae. Paper is a methodology review with no primary heavy-metal measurements — ingested as out-of-core-scope methodology / regulatory-context reference per the lai2025-infant-diaper-phthalate-dna-oxidation precedent. Routed to [[products/diapers-and-components]] (HMTc Cat 9 Row 7 scaffold) and [[products/menstrual-pads]] (HMTc Cat 15 Row 2 scaffold) for discoverability as a multi-product methodology reference; metals: [] correctly reflects no metal occurrence data.

Page history

The five most recent substantive edits to this page. The full version history lives in git; when DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.

CommitDateDescription
ce3e07c2026-05-28activation | Vercel DATACITE env slots set, curators.md filled with founder entry + six scoped reviewer invitations, peer-review onboarding playbook drafted
51400b92026-05-28audit-queue: gasparik2017-wild-boar-slovakia-metals audited-revised