Adams et al. 2017 - Nigerian processed spices metals

Adams et al. tested four Nigerian spice products for genotoxicity, microbial load, proximate composition, and heavy-metal content. The heavy-metal table is direct spice occurrence evidence for cadmium and nickel in curry, thyme, suya spice, and pepper-soup spice, with lead reported as not detected in all four products. Pepper-soup spice was the only product with detectable chromium.

Key numbers

All heavy-metal values in Table 5 are reported in mg/kg spice.

The paper lists standard-limit comparator values of 5.0 mg/kg for Pb, 0.20 mg/kg for Cd, and 1.63 mg/kg for Ni. The authors state that all four spices had cadmium above the cited standard limit and that only suya spice had nickel above the cited standard limit. The reported p-value row in Table 5 is 0.222 for Cd and 0.199 for Ni.

Methods (brief)

The spice samples were ashed, dissolved with concentrated nitric acid, evaporated to dryness, digested with hydrochloric acid, filtered hot through Whatman No. 4 paper, and made up to 100 mL. Minerals were determined by flame atomic absorption spectrometry (FAAS) with a hollow-cathode lamp and a fuel-rich flame. The paper does not report LOD/LOQ values for the heavy-metal table, so non-detects should remain source-level ND values rather than zeroes.

Implications

Certification: This source contributes occurrence evidence for Cd and Ni in mixed spice products from Nigeria, with a single Cr detection in pepper-soup spice and Pb not detected across the four sampled products.

Courses: The paper is useful for teaching that informal or culturally specific spice mixtures can differ from standardized packaged spices in microbial and metal findings.

App: Broad spice-category routing is appropriate; the paper does not provide enough brand-neutral commodity detail to assign all findings to individual ingredient pages.

Microbiome (if applicable): The paper reports microbial counts for suya and pepper-soup spices, but it does not study human or food-system microbiome effects.

Wiki pages this source may touch

• Spices
• Cadmium
• Nickel
• Lead
• Chromium

Verification notes

The PDF title, byline, DOI, year, journal, methods, and Table 5 values were read from the auto-fetched PDF. The routeable metals are total Pb, Cd, Cr, and Ni as reported by AAS; the source does not provide chromium speciation and does not report whether Pb non-detects reflect a specific detection limit.

The paper has internal inconsistencies between Table 5 and the Discussion/Conclusion body text. Table 5 reports standard-limit values of 0.20 mg/kg (Cd) and 1.63 mg/kg (Ni), while the Discussion body text states the limits as 0.02 mg/kg (Cd) and 0.163 mg/kg (Ni); the Discussion also gives a single Cd figure of 0.426 mg/kg (the unweighted mean across the four spices) and the Conclusion cites suya-spice nickel as 3.223 mg/kg where Table 5 shows 3.258 mg/kg. The wiki page cites Table 5 values throughout because the table is the primary data report; the inconsistencies are flagged here so a future auditor does not mistake them for wiki transcription errors.

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.