Dokubo et al. 2023 — Heavy metals in Nigerian seasoning powders (IJSHR)

This original research article measured ten metals (As, Cr, Ni, Pb, Cd, Fe, Co, Cu, Mn, V) in four brands of commercially sold dry seasoning powder purchased in Port Harcourt, Nigeria, using Flame Atomic Absorption Spectrophotometry, and computed adult-population health-risk indices (Estimated Daily Intake, Hazard Quotient, Hazard Index, and Cancer Risk) using the USEPA model. Mean Pb (6.35 ± 1.07 mg/kg) and mean Cd (0.53 ± 0.09 mg/kg) across the four brands exceeded the FAO/WHO Maximum Permissible Limits of 5.0 mg/kg and 0.3 mg/kg respectively. One brand (SP4) carried Pb at 12.61 mg/kg, more than 2.5× the MPL. Arsenic and chromium were not detected in any sample. The summed Hazard Index exceeded 1.0 for one brand (SP2 HI = 1.04). The combined Excess Cancer Risk for Ni + Pb + Cd exceeded the 1×10⁻⁴ upper bound in all four brands.

Key numbers

Mean concentrations across the four brands (mg/kg, dry sample basis):

• Pb: 6.35 ± 1.07 (above FAO/WHO MPL 5.0 mg/kg)
• Cd: 0.53 ± 0.09 (above FAO/WHO MPL 0.3 mg/kg)
• Fe: 16.31 ± 2.56 (highest of any measured metal; below WHO MPL)
• V: 0.16 ± 0.10 (lowest)
• As: not detected in any sample
• Cr: not detected in any sample
• Co, Cu, Mn, Ni: mean values not given in text; ordering in §3.3 was Fe > Co > Pb > Mn > Ni > Cu > Cd > V

Per-brand Pb (mg/kg, Figure 2 / §3.1):

• SP1: 5.94 ± 0.02 (above MPL)
• SP2: not stated in text; derivable from Table 4 EDI of 0.171 µg/kg/day as ≈1.11 mg/kg (below MPL)
• SP3: 5.72 ± 0.07 (above MPL)
• SP4: 12.61 ± 0.03 (≈2.5× MPL)

Per-brand Cd (mg/kg, §3.1):

• SP1: 0.35 ± 0.02 (above MPL)
• SP2: 0.96 ± 0.03 (above MPL)
• SP3: not stated in text; derivable from Table 4 EDI of 0.0385 µg/kg/day as ≈0.25 mg/kg (below MPL)
• SP4: 0.56 ± 0.01 (above MPL)

Per-brand Ni (§3.1): SP4 at 8.24 ± 0.01 mg/kg, above WHO MPL of 5.0 mg/kg. Other brands not stated in text.

Per-brand Co (§3.1, above the WHO MPL of 3.5 mg/kg the authors cite): SP1 3.86 ± 0.02; SP3 3.67 ± 0.02; SP4 7.66 ± 0.04.

Per-brand Mn (§3.1, above the WHO MPL the authors cite): SP2 10.45 ± 0.04; SP4 2.78 ± 0.04.

Estimated Daily Intake for Pb (Table 4, µg/kg-bw/day; FAO/WHO tolerable limit 0.5 µg/kg/day): SP1 0.912; SP2 0.171; SP3 0.881; SP4 1.940. Three of four brands exceeded the tolerable limit; SP4 was ≈4× the limit.

Hazard Index summed across measured metals (Table 5): SP1 0.35; SP2 1.04; SP3 0.26; SP4 0.83. Only SP2 exceeded the threshold of 1.

Excess Cancer Risk (ILCR, sum of CR for Ni + Pb + Cd; Table 6, USEPA acceptable upper bound 1×10⁻⁴): SP1 5.31×10⁻⁴; SP2 31.99×10⁻⁴; SP3 6.01×10⁻⁴; SP4 16.7×10⁻⁴. All four brands exceeded the upper bound; ordering SP2 > SP4 > SP3 > SP1. The dominant per-metal contributor differed by brand: Cd dominated in SP1 (Cd CR 95.8×10⁻⁴) and SP2 (Cd CR 29.2×10⁻⁴), while Ni dominated in SP3 (Ni CR 3.70×10⁻⁴ vs Cd CR 2.43×10⁻⁴) and SP4 (Ni CR 11.5×10⁻⁴ vs Cd CR 5.05×10⁻⁴). Pb CR values were within the acceptable range in every brand (1.45×10⁻⁶ to 1.65×10⁻⁵).

USEPA model parameters: adult body weight 65 kg, daily seasoning-powder ingestion 0.01 kg, exposure frequency 365 days/year, exposure duration 54 years, lifetime 54 years.

Methods (brief)

Flame Atomic Absorption Spectrophotometry (FAAS), model GBC 908PBMT. Sample preparation: 2 g of each dried sample digested with 2 mL concentrated HNO₃, 10 mL concentrated HCl, and 2 mL H₂SO₄, heated until a clear solution evolved, cooled 30 min, filtered, and made up to 50 mL with distilled water. No LOD/LOQ values, no certified reference material, no replicate digestions, and no recovery data are reported; the methods section states only that “adequate quality assurance measures were carried out.” Health-risk indices computed per USEPA (EDI, HQ, HI, CR). Statistical analysis: SPSS v26; values reported as mean ± SD. Evidence tier B reflects the small sample (n = 4 brands, single city), the lower analytical sensitivity of FAAS relative to ICP-MS, the absence of reported LOD/LOQ or recovery data, and that the journal (IJSHR) is a general health-sciences venue with moderate indexing. Arsenic non-detection in particular should be read with caution given that FAAS detection limits for As are typically in the high-µg/kg to mg/kg range, so true low-µg/kg contamination would not be visible. The Pb and Cd exceedances are large enough relative to MPLs that the headline finding is analytically robust even with FAAS.

Implications

Certification: Seasoning powders / bouillon-style flavor-enhancer powders are not a current HMT&C product category. This study contributes Africa / West Africa supply-chain data for Pb, Cd, and Ni in commercial Nigerian-market seasoning blends.

Courses: Useful case study for the processed-foods module: bouillon-style seasoning powders aggregate exposure from multiple ingredient inputs (salt, vegetable extracts, spices, starch, glutamate), and the high daily-use pattern of these products in West African cooking compounds per-unit contamination into clinically relevant intake even at modest mg/kg levels.

App: Commercial seasoning / bouillon powders in West African markets are a flag for Pb, Cd, and Ni exposure; the ingredient-list cue is “flavor enhancer” / “seasoning powder” / “bouillon” as a discrete product, not a single spice or vegetable.

Wiki pages updated on ingest

• condiments-general
• spices
• lead
• cadmium
• nickel

Verification notes

2026-05-18 merge-enhance pass (Claude, /ingest-next-manual-fetch-pdf v2):

• Corrected raw_handle from the legacy placeholder papers-cube to the per-skill handle PCMF_ijshr12.
• Added raw_sha256 (207c26632a…) and access_url (DOI resolver) to frontmatter for provenance.
• Set ingredients: []: the previous values [[ingredients/seasoning-powder]] and [[ingredients/bouillon]] were invented slugs (no such pages exist in the current taxonomy). The paper measures contamination at the finished-product level, not at any isolated single ingredient; product-level routing via condiments-general and spices captures the actual scope without overspecifying frontmatter.
• Expanded metals: to the full set of analytes the paper measured, including the As and Cr non-detections (Cr, tAs added) and the non-toxicology trace metals (Fe, Co, Cu, Mn, V) the paper reported alongside Pb/Cd/Ni. As is recorded as tAs because FAAS does not speciate.
• Replaced the previous flat “above the acceptable range” CR statement with the actual Table 6 data: per-metal Pb CR was inside the acceptable range in every brand; the binding finding is the ILCR sum exceeding 1×10⁻⁴, driven primarily by Cd.
• Added derived per-brand values for SP2 Pb (≈1.11 mg/kg) and SP3 Cd (≈0.25 mg/kg) back-calculated from the Table 4 EDI values, flagged as derived. The paper omits these specific brand cells from the text but they are recoverable from the EDI arithmetic.
• Added per-brand Ni, Co, and Mn cells the paper does state.
• Removed the synthesis claim “consistent with broader literature on processed spice contamination” from the Certification line (Part 2 wiki/HMTc firewall — single-source page should not synthesize across the corpus).
• Strengthened the Methods section with the omitted-QA detail: no LOD/LOQ, no CRM, no replicate digestion, no recovery data reported.
• Brand-firewall check: Table 1 of the paper names four commercial brands (Spicity Stew and Jollof, Lasor Chicken, Kitchen Glory, Onga Classic). The wiki page deliberately preserves only the anonymous SP1–SP4 codes per Part 12. No brand names appear anywhere on this page.

2026-05-18 audit-subagent pass (general-purpose Agent, fresh context):

• ⚠️ Subagent flagged the original “dominant per-metal CR contributor was Cd” claim as over-broad. Verified against Table 6 (PDF p. 5): Cd-dominant holds for SP1 (95.8×10⁻⁴ Cd vs 4.27×10⁻⁴ Ni) and SP2 (29.2×10⁻⁴ Cd vs 2.78×10⁻⁴ Ni); Ni-dominant for SP3 (3.70×10⁻⁴ Ni vs 2.43×10⁻⁴ Cd) and SP4 (11.5×10⁻⁴ Ni vs 5.05×10⁻⁴ Cd). The subagent caught SP4 but missed SP3; the wiki was wrong in both. Corrected the Key-numbers sentence to enumerate by brand.
• ⚠️ Subagent flagged products/condiments-general as not present in docs/gpt-collaboration/taxonomy-snapshot.md. Verified independently — wiki/products/condiments-general.md exists in the live wiki (the routing audit also produces a row for it for this source). The taxonomy snapshot is stale; the slug is valid. False positive against the source page, real flag against the snapshot. Leaving slug in place.
• Subagent verdict: REVISE. All other findings (numerical fidelity, speciation/methods, brand firewall, Part 2 firewall) were clean.

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.