Alizadeh et al. 2017 - Mercury and lead in Mashhad bar soaps

Alizadeh, Balali-Mood, Mahdizadeh, and Riahi-Zanjani measured total mercury and total lead in 32 bar-soap samples purchased from the Mashhad, Iran retail market in 2016, spanning four anonymized cosmetic-soap brands, five anonymized hygiene-soap brands, and two anonymized contraband-soap product lines. All values were below the FDA cosmetic-material comparators of 1 µg/g for mercury and 20 µg/g for lead the authors invoke. Contraband-soap mercury was significantly higher than cosmetic (P<0.01) and hygiene (P<0.05) soap mercury. The paper also reports a within-hygiene-category significant difference between brands P and T, but the source narrative and Table 3 disagree on whether the contrast is in lead or mercury (see Verification notes). The highest mean mercury was reported for one of the two contraband lines (0.39 µg/g) and the highest mean lead for the P hygiene brand (0.36 µg/g).

Key numbers

All concentrations are in µg/g (= mg/kg) of finished soap as purchased. The FDA comparators the source invokes for soap and cosmetic materials are 1 µg/g for mercury and 20 µg/g for lead.

Overall category means (Table 1; mean ± SEM)

Contraband mercury was significantly higher than cosmetic (P<0.01) and hygiene (P<0.05) soap mercury. Lead differences across the three categories were not statistically significant.

Cosmetic-soap brands (Table 2; mean ± SEM, n=3 per brand)

No significant differences across cosmetic brands.

Hygiene-soap brands (Table 3; mean ± SEM, n=3 per brand)

Significant P-vs-T contrast (P<0.05): the source’s prose describes this as a lead contrast, but the asterisk in source Table 3 is printed on the mercury column. The contradiction is preserved here rather than silently resolved (see Verification notes).

Contraband-soap lines (Table 4; mean ± SEM)

No significant differences between the two contraband lines.

Methods (brief)

Soap samples were purchased from the Mashhad retail market in 2016. Lead was measured by atomic absorption spectrometry with graphite furnace on a Perkin Elmer model 3030 instrument. Total mercury was measured by a mercury/hydride system; the source does not explicitly state whether the mercury/hydride system is integrated with the Perkin Elmer 3030 or is separate instrumentation. Method reliability was evaluated by spiking five samples and computing recovery, detection limit, and accuracy; reported accuracy was 98.4% for mercury and 99.4% for lead. Statistical analyses used SPSS for Windows version 11.5 with a P<0.05 significance threshold; values are reported as mean ± SEM. The paper does not report numerical LOD or LOQ values, does not separate mercury species (results are total mercury), does not state per-brand sample counts explicitly for the hygiene category (presumed three samples per brand by parallel with the cosmetic-category statement), and does not report digestion procedure detail.

Implications

Certification: Provides finished-product Pb and total-Hg occurrence values for an anonymized Iranian-market bar-soap panel. The usable concentration basis is finished product as purchased; the values are not food-occurrence data and should not be routed into dietary benchmark pools. All values are well below the 1 µg/g Hg and 20 µg/g Pb FDA cosmetic-material comparators the source invokes.

Courses: A compact example of a single-market personal-care heavy-metal panel, illustrating how contraband or unregistered soap categories can carry meaningfully higher mercury than registered cosmetic and hygiene lines in the same market even when all values remain below a regulatory cosmetic-material comparator.

App: Supports Iran-market personal-care context for bar soaps. Because the source reports a small panel (n=32) with anonymized commercial brands, app use should frame the values as a small surveillance study, not a national distribution.

Microbiome: Not addressed.

Wiki pages this source may touch

• bathing-soaps
• lead
• mercury-total

Verification notes

• DOI: the PDF does not print a DOI. The article is cited as IJT 2017 (4): 1-3, Volume 11, Number 4, July-August 2017, accessed via http://www.ijt.ir. doi left null and no_doi_assigned: true.
• Brand firewall (CLAUDE.md Part 12, strict 2026-05-17 reading):
  • The single-letter codes F, D, S, L (cosmetic) and P, Y, T, G, A (hygiene) are the authors’ own anonymization of commercial brand identities, not commercial brand names; the source page preserves them as anonymized sample codes.
  • The two named contraband-soap lines printed in source Tables 1 and 4 are anonymized here as Contraband-A and Contraband-B. An earlier draft of this page named them under Part 12 Exception 1 (regulatory-event subject) reasoning, but the source itself does not document any Congressional investigation, FDA recall, or agency enforcement action against the named lines; the Exception 1 framing was an extrapolation from outside knowledge rather than from the source. The strict reading is applied: aggregate as anonymized contraband lines, do not name. The within-contraband statistical contrast (no significant Halazoon-vs-Kharchang difference per source Table 4) is preserved under the anonymized codes; per-line means and SEMs are preserved because they are the data the paper reports for the contraband category.
• Paper-internal contradiction on the P-vs-T hygiene-brand significant difference: source prose (Results paragraph, p.2) reads “P soap significantly had higher levels of lead as compared to T brand (P<0.05) (Table 3),” but source Table 3 prints the asterisk on P’s mercury column value (0.14 ± 0.026*) with the footnote “P<0.05 indicates significant changes compared to the T soap.” The prose names lead; the asterisk location names mercury. Both interpretations are preserved on this page; neither is silently selected. The opening narrative and the Hygiene-soap-brands subsection both flag the contradiction in line. No outside resolution is attempted.
• Speciation discipline: mercury values are total mercury (mercury/hydride AAS, no organic/inorganic separation). Recorded as tHg in frontmatter and in body tables.
• Per-brand hygiene-soap sample counts are not explicitly stated in the source. Total n=32 is computed under the assumption that the “three samples from” phrasing extends from the cosmetic category to the hygiene category (4×3 + 5×3 + 2 + 3 = 32). Flagged in Methods.
• Slug routing: products: [[products/bathing-soaps]] is the live taxonomy slug (provisional scaffold under wiki/products/bathing-soaps.md, created 2026-06-02 by the oviri2024 Nigerian-bathing-soaps ingest). The slug is newer than the taxonomy-snapshot.md generation date (2026-05-18), so audit passes that reference the older snapshot may flag it as missing; routing audit accepts it as a direct_evidence target.
• Evidence Fitness: B-tier / small single-city surveillance panel. Limitations: n=32 across three categories with brand-level n=2-3, no LOD/LOQ reported, no mercury speciation, no inductively coupled plasma mass spectrometry validation, single-market sampling, brand names anonymized so values cannot be tied back to specific commercial products. Evidence tier set to B (not A) because of the absent LOD/LOQ reporting, the absent digestion-procedure detail, and the small per-brand n.
• HMTc firewall (CLAUDE.md Part 2): no percentile arithmetic, no threshold proposals, no comparison to HMTc-certified products. The FDA cosmetic-material comparators (1 µg/g Hg, 20 µg/g Pb) are transcribed only as the source’s own comparator, not as wiki claims.
• Fresh-context audit (Claude subagent, 2026-06-03): QUARANTINE verdict. Audit findings reviewed and applied as follows. (1) Check 2 invented-slug ❌ on bathing-soaps — verified false positive: slug exists in live wiki as 2026-06-02 provisional scaffold; the taxonomy-snapshot.md the audit referenced was generated 2026-05-18 and is stale. Routing audit accepts the slug as a direct_evidence target with zero unresolved entries. No change to frontmatter; slug-routing rationale added to Verification notes for future audits running against stale snapshots. (2) Check 4 brand firewall ❌ on Halazoon/Kharchang naming — verified correct: source does not document any regulatory event against the named lines; Exception 1 invocation was unsupported. Names replaced with anonymized Contraband-A / Contraband-B in narrative, Table 1 implicit reference, Table 4 header column, and Implications. (3) Check 1 ⚠️ on P-vs-T significance footnote — verified correct paper-internal contradiction: source prose says lead, source Table 3 asterisk says mercury. Both interpretations preserved; contradiction flagged in narrative, table caption, and this Verification note. (4) Check 3 ⚠️ on “same instrument” inference — verified correct: source does not explicitly tie the mercury/hydride system to the Perkin Elmer 3030. Methods reworded to say “a mercury/hydride system” with explicit unclear-integration flag.

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.