Oviri et al. 2024 - Heavy metals in Nigerian bathing soaps

Oviri, Tesi, and Emoyan measured Pb, Ni, Zn, Co, Cd, and total Cr in 17 bathing soaps sold in Abraka, Delta State, Nigeria. The sampled categories were medicated, moisturizing, toilet, and skin-whitening soaps; the paper reports both individual anonymous sample values and category-level mean, median, and range statistics in mg/kg finished product. Across Table 2, Pb ranged 0.08-0.28 mg/kg, Cd 0.02-0.05 mg/kg, Ni 0.05-0.24 mg/kg, total Cr 0.01-0.09 mg/kg, Co 0.33-1.93 mg/kg, and Zn 0.10-6.42 mg/kg. The authors also calculated dermal systemic exposure doses and margins of safety using SCCS cosmetic-exposure defaults and concluded that all MoS values were above 100.

Key numbers

All concentration values below are from source Tables 2 and 3, in mg/kg finished soap as sold. Multiply by 1000 for ppb or ug/kg.

Individual anonymous soap samples

Category summaries

Exposure-modeling outputs

Table 4 reports systemic exposure dose (SED) under 50% and 100% bioaccessibility assumptions. At 50% bioaccessibility, maximum SED values were Cd 0.002, Pb 0.011, Cr 0.004, Co 0.075, Ni 0.007, and Zn 0.250 ug/kg bw/day. At 100% bioaccessibility, maximum SED values were Cd 0.004, Pb 0.022, Cr 0.007, Co 0.150, Ni 0.019, and Zn 0.500 ug/kg bw/day. The text states calculated MoS values for all investigated metals were greater than 100 at both bioaccessibility assumptions.

Methods (brief)

The authors purchased 17 soaps from supermarkets in Abraka, Delta State, Nigeria. They digested 1.0 g of each soap sample overnight in concentrated nitric acid, perchloric acid, and hydrochloric acid, heated the mixture to 125 C for two hours, filtered, diluted to 25 mL with 0.25 mol/L nitric acid, and analyzed Cd, Pb, Ni, Cr, Co, and Zn in triplicate by flame atomic absorption spectrophotometry using a Perkin Elmer Analyst 200. Blanks were processed in parallel; glassware was soaked in 10% nitric acid and rinsed with deionized water. Spike recoveries were 89.5-98.8%. The paper does not report LOD or LOQ values and does not speciate chromium.

The exposure model used a 60 kg adult body weight, SCCS default soap amount 18.67 g/day, exposed skin surface area 17,500 cm2, application frequency 1.43/day, retention factor 0.01, and 50% and 100% oral-bioavailability scenarios. The source treats MoS >= 100 as the no-health-risk benchmark.

Implications

Certification: This source contributes finished-product occurrence values for a provisional bathing-soaps product class and a three-sample skin-whitening soap subset. The usable concentration basis is finished product as sold; the values are not food-occurrence data and should not be routed into dietary benchmark pools.

Courses: Useful as a compact example of dermal rinse-off exposure modeling layered on finished-product heavy-metal measurements. It also illustrates why source tables should be preferred over abstract summaries when the two disagree.

App: Supports Nigeria-market personal-care context for bathing soaps and skin-lightening soaps, with concentration ranges and MoS-oriented exposure calculations. Because the source reports anonymous sample codes rather than market-share-weighted sampling, app use should frame the values as a small occurrence study, not a national distribution.

Microbiome: No microbiome data.

Wiki pages this source may touch

• bathing-soaps
• skin-lightening-cream
• lead
• cadmium
• nickel
• chromium
• zinc

Verification notes

• DOI and metadata were verified from the PDF first page: DOI 10.33003/fjs-2024-0803-2500, FUDMA Journal of Sciences Vol. 8 No. 3 Special Issue, June 2024, pp. 422-430, authors Victory I. Oviri, Godswill O. Tesi, and Onoriode O. Emoyan.
• The abstract reports wider ranges for several metals (Pb up to 0.39 mg/kg, Ni up to 0.33 mg/kg, Cd up to 0.09 mg/kg, Cr up to 0.19 mg/kg). Tables 2 and 3 instead report Pb max 0.28, Ni max 0.24, Cd max 0.05, and Cr max 0.09 mg/kg. The source page uses the table values because Tables 2 and 3 provide the analyte-by-sample and category-summary data; the abstract mismatch is retained as a paper-internal discrepancy, not silently corrected.
• The wishlist filename routed this PDF through whitening-products-cd-product, but the current [[products/whitening-products]] slug is an oral-care tooth-whitening row. This PDF is about skin and bath soaps, so it is not routed to oral-care whitening products. The three skin-whitening soap samples are routed as context for the existing skin-lightening product/advisory surface.
• Brand names listed in source Table 1 are intentionally omitted. The source page preserves anonymous sample IDs and category labels only, under CLAUDE.md Part 12 brand-firewall rules.
• Evidence Fitness: EF-2 / routeable small-panel occurrence evidence for finished bathing soaps and skin-whitening soaps. Limitations: n=17 total, no LOD/LOQ reported, chromium not speciated, and sampling is local to one Nigerian market area.

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.