Overview
A short three-page Academic Journals Inc. paper quantifying lead, cadmium, nickel and total chromium in nineteen soap and detergent products purchased from open-market vendors in Akure, Ondo State, southwestern Nigeria, in July 2006. The sample mix spans toilet (bath/hand) soaps, multi-purpose bar soaps, powdered laundry detergents, a liquid laundry detergent, and one locally produced hand-mould soap. Quantification used dry ashing at 500 °C followed by 2 M HCl dissolution and analysis on a SP 9 Pye Unicam atomic absorption spectrophotometer at triplicate determinations per sample. The paper reports only pooled-distribution statistics (minimum, maximum, mean, standard error of the mean across all nineteen samples) for each metal; per-sample concentrations are not tabulated. Cadmium was below the detection limit in every sample (no LOD value is reported). Pooled means across the nineteen-sample distribution were lead (Pb) 3.78 mg/kg, nickel (Ni) 2.20 mg/kg, and total chromium (Cr) 1.33 mg/kg on a dry-product, as-purchased basis. The authors do not propose threshold comparisons against any cosmetic, household-cleaning or food regulatory ceiling; the framing throughout is descriptive (“the values obtained for the trace heavy metals determined were low, there is a cause for vigilance”) and the discussion section places the Akure results in context against other authors’ values for unrelated matrices (tea leaves, deer tissue, street dust, shrimp, coots) rather than against soap- or detergent-specific reference data.
Key numbers
Pooled-distribution statistics across all 19 samples (Table 2, p. 104; units mg/kg of finished product on a dry-ashed basis):
Cadmium was below the detection limit in every sample; the paper reports no numeric LOD value and no recovery, blank, or certified-reference-material data against which to interpret the “ND” floor.
Sample-composition breakdown (Table 1, p. 103; brand columns suppressed per Part 12):
| Product form (as described in Table 1) | Provenance descriptor | Count | Package descriptor (Table 1) |
|---|---|---|---|
| Toilet soap | Industrial (Nigerian factory) | 4 | Cellophane (4) |
| Toilet soap | Imported | 4 | Cellophane (3); paper (1) |
| Toilet soap | Local | 1 | No package descriptor |
| Bar soap | Industrial | 1 | No package descriptor |
| Bar soap | Local | 2 | No package descriptor |
| Hand-mould soap | Local | 1 | No package descriptor |
| Powdered detergent | Industrial | 4 | Cellophane (2); paper (1); no package descriptor (1) |
| Liquid detergent | Imported | 2 | Plastic (2) |
| Total | 19 |
Pearson correlation coefficients (Results & Discussion narrative, p. 103) between the analytes and the full sample set at 95 % confidence level:
- Pb: r = 0.969
- Ni: r = 0.835
- Cr: r = 0.806
(Cd is omitted because it was below detection limit throughout.) The paper does not specify what the correlation is between — the wording is ambiguous (“good correlation between the metals and all the samples”); a literal reading is correlation between the rank of the metal value and the rank of the sample index, but the authors do not state the second variable and the wiki does not impute one.
Authors’ verbal cluster statement (Results & Discussion, p. 103, brand attribution stripped per Part 12): the paper reports that “Pb, Ni and Cr contents were significantly higher” in five specific brand-named products (a subset of industrial toilet soaps and industrial powdered detergents) compared to the rest of the sample, and concludes that “the samples varied in the uptake of metals” while noting that “the type of package and manufacture had no significant influence on other variable.” No statistical test is named to substantiate the “significantly higher” claim and no per-sample values are tabulated to verify the cluster.
Methods (brief)
Sample acquisition. Nineteen soap and detergent samples were purchased from open-market vendors in Akure, Ondo State, Nigeria in July 2006. The paper does not state per-sample purchase locations, lot numbers, manufacturing dates, retail prices, or vendor identities. Each sample is identified in Table 1 by brand name plus a four-category type label (toilet soap, bar soap, hand-mould, detergent, liquid detergent), a three-category manufacture label (local, industrial, imported), and a three-category package label (cellophane, paper, plastic, or none).
Sample preparation and digestion. Approximately 0.5 g of each sample was dry-ashed in a muffle furnace at 500 °C for 1 hour. The ash was dissolved in 2 M hydrochloric acid, filtered, and made up to 50 cm³ with 2 M HCl in a volumetric flask.
Instrumentation. A SP 9 Pye Unicam atomic absorption spectrophotometer (Mercedes, 2002, cited as method reference) was used to quantify Pb, Cr, Ni and cadmium (Cd). Per-element wavelengths reported in the Materials and Methods section:
- Cd: 217 nm
- Cr: 262 nm
- Pb: 283.3 nm
- Ni: 260 nm
The reported wavelengths for Cd (217 nm), Cr (262 nm) and Ni (260 nm) do not correspond to the standard primary atomic-absorption resonance lines for these elements (Cd 228.8 nm; Cr 357.9 nm; Ni 232.0 nm); the Pb wavelength (283.3 nm) is the conventional secondary Pb line. The wiki reports the wavelengths as published and flags the discrepancy from standard practice under Limitations rather than substituting external values.
Replicates. “At least triplicate determinations were carried” on each sample (p. 102). The paper does not report whether the triplicate is at the digestion or instrument-aspiration stage, and does not propagate the within-sample variance into the Table 2 standard-error reporting.
Quality control and detection limits. No certified reference material, internal standard, blank, recovery percentage, instrumental detection limit, method detection limit, calibration range, or measurement-uncertainty value is reported. The “ND” floor for Cd is asserted without numeric anchoring.
Speciation. Total metals only. The paper measures total chromium and does not distinguish hexavalent chromium (Cr-VI) from Cr-III. No arsenic or mercury speciation issues arise because neither analyte is measured.
Basis. Concentrations are reported as mg of metal per kg of finished product on a dry-ashed, as-purchased basis. The paper does not report moisture content, ash content, or any factor that would allow conversion between the dry-ashed basis and the as-used (lathered, diluted) basis of these products.
Implications
- The dataset adds a small (n = 19) regional view from southwestern Nigeria (Akure, Ondo State) to the very thin global literature on trace metals in commercial soaps and detergents. Three of the four analytes measured (Pb, Cd, Ni) are on the HMTc certification analyte panel; total Cr is measured rather than the priority-panel sub-form Cr-VI, so the chromium values inform the broader chromium literature but do not directly bind Cr-VI threshold-setting.
- Cadmium below the detection limit in every sample is the most reportable finding for HMTc purposes, but the absence of a numeric LOD makes the Cd result unusable for quantitative bounding. The Pb (mean 3.78, max 5.80 mg/kg) and Ni (mean 2.20, max 3.10 mg/kg) ranges measured here are appreciably higher than the per-kg concentrations reported in other corpus papers on the Nigerian bathing-soap matrix; whether the apparent gap reflects genuine market-and-vintage differences (Akure 2006 vs Delta 2024), method differences (dry-ashing at 500 °C vs aqua-regia hot-plate digestion), or reporting-quality differences across source venues is a Part 9 synthesis-pass question and quantitative comparators are deferred to that workflow rather than tabulated here.
- The paper does not report per-sample values, so the dataset cannot contribute to a percentile distribution of Nigerian soap/detergent metal concentrations; only the pooled minimum, maximum, mean and standard error are recoverable. Downstream pooling will use the four marginal summary statistics for each metal as a single distribution-summary record per metal per source, not as a per-sample contribution.
- The authors propose no regulatory threshold comparison, no HMTc-relevant exposure calculation, and no margin-of-safety analysis. The framing is exploratory and descriptive. No threshold values are proposed by this source page.
Limitations
- Small-journal venue with thin reporting standards. Research Journal of Environmental Toxicology (Academic Journals Inc., Lagos / Wuhan / Online), ISSN 1819-3420, has been flagged in several index-quality assessments as a low-rigour venue with limited editorial peer-review depth. The article itself shows characteristic features (no QC/recovery/LOD data, no method validation, no statistical-test naming for the “significantly higher” cluster claim, multiple grammatical and typesetting inconsistencies) consistent with that venue. Treated as C-tier evidence on the HMI ladder accordingly.
- No per-sample values. Table 2 reports only the pooled-distribution minimum, maximum, mean and SEM across all nineteen samples for each metal. The cluster statement in the discussion text (“Pb, Ni and Cr were significantly higher in [five named brands]”) therefore cannot be verified against tabulated data; the wiki reports the cluster statement only as the authors’ verbal claim with brand attribution stripped.
- No detection-limit anchor. “Cd was below detection limit” is reported with no numeric LOD value. The result is therefore qualitative: it bounds Cd at “less than whatever the SP 9 Pye Unicam achieves under these digestion conditions at 217 nm”, which cannot be translated to a regulatory-comparable ceiling.
- Non-standard AAS wavelengths reported. The reported per-element wavelengths for Cd (217 nm), Cr (262 nm) and Ni (260 nm) are not the conventional primary atomic-absorption resonance lines (Cd 228.8 nm; Cr 357.9 nm; Ni 232.0 nm). The Pb wavelength (283.3 nm) is a conventional secondary line. The paper offers no calibration or sensitivity rationale for the chosen wavelengths. If the printed wavelengths reflect actual instrument settings, the sensitivity and selectivity of the measurements for Cd, Cr and Ni are likely degraded relative to a standard configuration; if they are typesetting errors for the standard lines, the documentation is unreliable. The wiki reports the wavelengths as published and flags the issue rather than substituting external values.
- No replicate variance propagation. “Triplicate determinations” are stated to have been carried out but the within-sample variance is not reported alongside the pooled standard-error-of-the-mean statistic in Table 2.
- No certified reference material, blank, or recovery data. None reported.
- Total chromium only. The paper measures total Cr and does not distinguish Cr-VI from Cr-III, so the chromium values cannot be applied directly to Cr-VI threshold-setting.
- Ambiguous correlation reporting. The paper reports correlation coefficients (Pb r = 0.969, Ni r = 0.835, Cr r = 0.806) without naming the second variable in the correlation. A literal reading is correlation between metal-rank and sample-index, but the authors do not state this and the wiki does not impute the second variable.
- Brand-by-brand attribution in the discussion section. Five specific brand names are listed in the discussion as having “significantly higher” Pb/Ni/Cr concentrations. The wiki strips brand attribution per Part 12 and reports only the product-form-and-provenance cluster (“a subset of industrial toilet soaps and industrial powdered detergents”). The underlying per-brand values are not tabulated in the source and cannot be recovered.
- Folder-vs-content mismatch. The source PDF was filed in the archived source file, but the paper is about soaps and laundry detergents, not toilet-bowl / bathroom descalers. The folder-level mis-categorisation is a manual-fetch-tracker note, not a content defect.
Provenance
- Source PDF: the archived source file
- SHA-256:
e37c78817569980591b0a844d9e1e2f77c5dabc641c7cb47545f3ea12a5628b5 - File size: 201 KB; 4 pages (cover, abstract+methods p. 102, results p. 103, references p. 104).
- Journal: Research Journal of Environmental Toxicology, Volume 1, Issue 2, pages 102–104 (Academic Journals Inc.; ISSN 1819-3420).
- Publication date: 2007.
- DOI: none assigned (Academic Journals Inc. did not mint Crossref DOIs for this article as of access date).
- License: open-access per Academic Journals Inc. policy; the journal publishes under terms permitting redistribution with attribution. Quality of editorial oversight is independently disputed (see Limitations); the access terms themselves are open.
- Access date: 2026-06-03.
- Acquisition path: included in source-retrieval Agent Download Corruption Issue (KADC) folder
household_papers/02_Toilet_Bathroom_Descaler/. (Folder naming reflects raw-asset provenance, not topical fit — the paper is a soap-and-detergent study filed alongside toilet-and-bathroom-descaler literature in the KADC batch.)
Related evidence
- Lead
- Cadmium
- Nickel
- Chromium
- Bathing soaps
- Hand soap (liquid and bar)
- Laundry detergents (liquid, powder, pods/sheets, delicates)
- Heavy Metals Concentration In Body Creams Commonly Used In Delta State Tertiary Institutions And Their Implications For Human Health
- Analysis of heavy metals in Detergent Sample of Jhansi, India
- Nickel, Cobalt and Chromium in Consumer Products: Allergic Contact Dermatitis
Update history
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