Ma et al. 2024 — Heavy metals in sanitary napkins from seven countries
Ma et al. measured eight metals in 56 sanitary-napkin samples collected from China, Japan, South Korea, the United States, the United Kingdom, Australia, and Germany. The study reports country-level median concentrations and ranges in μg/kg for As, Co, Cu, Pb, Cd, Zn, Ni, and Cr. Arsenic and chromium were not speciated, so this page records arsenic as total arsenic and chromium as total chromium.
Key numbers
Table 1 reports median and range values in μg/kg for composite sanitary-napkin samples on the product-as-sold mass basis. The paper reports detection frequencies across the eight metals from 30.4% to 100%; Zn was detected in 94.6% of samples and Cr in 100% of samples.
| Country | tAs | Co | Cu | Pb | Cd | Zn | Ni | Cr |
|---|---|---|---|---|---|---|---|---|
| China (n=20) | 53.1 (<2.00-137) | 50.4 (<0.20-308) | 224 (36.6-1194) | <4.00 (<4.00-3674) | 4.89 (<0.20-15.5) | 6195 (936-99,420) | 5457 (<2.00-12,810) | 10,782 (7032-32,118) |
| Japan (n=6) | 3.33 (<2.00-69.0) | 32.2 (<0.20-370) | 41.1 (3.95-165) | <4.00 (<4.00-1407) | 0.56 (<0.20-15.7) | 4653 (13.5-11,754) | 45.9 (<2.00-881) | 28,863 (16,422-31,638) |
| South Korea (n=6) | <2.00 (<2.00) | <0.20 (<0.20-244) | 0.50 (<0.40-4.76) | <4.00 (<4.00) | <0.20 (<0.20-27.1) | 3300 (<8.10-8526) | <2.00 (<2.00-878) | 26,511 (24,612-29,580) |
| United States (n=6) | <2.00 (<2.00) | <0.20 (<0.20-8.08) | <0.40 (<0.40-38.4) | 924 (<4.00-3025) | 8.15 (<0.20-36.5) | 2355 (<8.10-4206) | <2.00 (<2.00) | 6202 (2580-18,462) |
| United Kingdom (n=6) | <2.00 (<2.00) | 1.51 (<0.20-25.4) | 27.6 (<0.40-466) | <4.00 (<4.00-4298) | 3.13 (<0.20-31.4) | 8082 (<8.10-140,580) | <2.00 (<2.00) | 2795 (1315-16,830) |
| Australia (n=6) | <2.00 (<2.00-7.23) | <0.20 (<0.20-50.8) | 53.2 (<0.40-143) | <4.00 (<4.00) | 2.14 (<0.20-17.1) | 5025 (216-7686) | <2.00 (<2.00) | 27,681 (19,488-37,512) |
| Germany (n=6) | <2.00 (<2.00) | 36.5 (<0.20-345) | <0.40 (<0.40-99.3) | <4.00 (<4.00-212) | <0.20 (<0.20-5.93) | 5829 (3660-13,620) | <2.00 (<2.00-617) | 23,409 (16,716-38,754) |
The source states that As, Co, Cu, Ni, and Cr differed significantly across countries (all p < 0.05). It reports the highest median As, Co, Cu, and Ni values in China, the highest median Cr in Japan, the highest median Pb and Cd in the United States, and the highest median Zn in the United Kingdom.
The source-side textile-standard comparison states that Cr, Ni, and Pb exceeded the comparator values in 96%, 23%, and 16% of total samples, respectively. The same paragraph identifies the comparator values as Pb 1.0 mg/kg, Ni 4.0 mg/kg, and Cr 2.0 mg/kg under the cited textile standards; this is the paper’s comparison, not an HMTc threshold.
For product-type comparisons, the paper reports no significant difference by pad thickness, significantly higher As, Ni, and Co in scented products than unscented products, and significantly higher Cu, Ni, As, and Co in low-priced products than high-priced products (p = 0.003, p = 0.004, p = 0.016, and p = 0.034, respectively). Cr was significantly higher in high-priced products (p = 0.047), with median Cr 24,840 μg/kg in high-priced samples and 11,658 μg/kg in low-priced samples.
Table 4’s “This study” row reports seven-country skin-contact daily exposure dose estimates in mg/kg-bw/d: As 5.52E-08, Co 1.40E-07, Cu 1.48E-06, Pb 1.10E-07, Cd 1.18E-07, Zn 1.57E-04, Ni 5.52E-08, and Cr 5.62E-04. The paper’s hazard-index calculation excludes As and Cr because dermal reference doses were not available; for the six included metals, HI ranged from 5.20 × 10-4 to 5.83 × 10-1, with median 3.50 × 10-2. The paper estimated carcinogenic risk only for Pb, reporting 5.36 × 10-10 to 6.92 × 10-7, with median 5.36 × 10-10.
Methods (brief)
The study selected representative sanitary-napkin products after questionnaire work in seven countries, then purchased three packs per selected type. Ten pieces were randomly selected from the packs, cut into 1.0 cm by 1.0 cm fragments, and composited from surface and middle layers; each composite sample had two parallel subsamples. Approximately 0.5 g of composite sample was digested with HNO3, H2O2, and HClO4 and analyzed by ICP-MS. Matrix-spike recoveries for As, Co, Cu, Pb, Cd, Zn, Ni, and Cr were 90.8%, 70.1%, 106%, 79.9%, 89.7%, 75.6%, 103%, and 97.6%, respectively, and LOQs were 0.20-8.10 μg/kg.
Implications
Certification: This is direct occurrence evidence for the menstrual-pads product category. Values are product-as-sold concentrations in μg/kg, with no wet/dry conversion and no analyte speciation. The source’s dermal-exposure calculations are exposure-model context and should not be treated as product concentration values.
Courses: The paper is useful for teaching the difference between a product-occurrence table, a source-side risk model, and a textile-standard comparator. It also provides a clean example of why total arsenic and total chromium must not be promoted to inorganic arsenic or Cr(VI).
App: The source supports a menstrual-pad evidence card for Pb, Cd, tAs, Ni, Cr, Zn, Co, and Cu, with country-level summary values and flags for source-side subgroup differences by scent and price but no brand-linked contamination values.
Microbiome: Not applicable.
Wiki pages this source may touch
Verification notes
Identity checks before drafting found no existing wiki/sources/ hit for DOI 10.1016/j.eti.2024.103606, raw handle MFK_1-s2-0-s2352186424000828-main, cite key ma2024-sanitary-napkins-metals, or the exact title. The DOI, title, authors, journal, year, and CC BY-NC-ND license were checked against the first page and PDF metadata. Table 1 values were re-opened from /tmp/hmi-fem-003.txt and checked against the source table; units remain μg/kg, and values below LOQ remain marked with <. Table 4 exposure estimates and Section 3.4 HI/CR values were checked separately and kept as source-side exposure context. The paper does not measure inorganic arsenic, Cr(VI), or any mercury species; frontmatter therefore uses tAs and Cr only. The source describes brand selection but this page intentionally reports only country/category and study-level statistics under the brand firewall. Frontmatter product and matrix slugs were checked against the closed taxonomy snapshot; no new slugs were invented. npm run evidence:source-routes exited 0 and generated one menstrual-pads route; routing_malformed.csv contains the same advisory-only missing-ingredients warning already present for other personal-care source pages because the closed ingredient vocabulary has no valid sanitary-napkin material slug, so ingredients: [] is intentionally retained.
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.
| Commit | Date | Description |
|---|---|---|
| 4039d20 | 2026-06-10 | scope: broaden ingest to the full upstream+downstream literature (marine, atmospheric, attribution, exposure, toxicology) — inclusion is the default |