Opening
This study measured trace metal concentrations in 26 commercially available infant formula samples sold in Port Harcourt, Nigeria. The analysis focused on determining whether essential trace metals were present in appropriate quantities for infant development, and estimated daily intake for five age groups: 0–2 weeks, >2 weeks to 4 months, 4–6 months, and 6–12 months. Samples comprised three formula types: milk-based (n = 9), cereal-based (n = 7), and cereal mix-based (n = 10).
Key Numbers
| Analyte | Milk-Based (μg/kg) | Cereal-Based (μg/kg) | Cereal Mix-Based (μg/kg) | Mean ± SD (μg/kg) |
|---|---|---|---|---|
| Iron | 7.32 ± 2.16 | 8.24 ± 1.92 | 7.88 ± 2.44 | 7.81 ± 2.17 |
| Zinc | 6.44 ± 1.88 | 7.16 ± 2.04 | 6.92 ± 1.76 | 6.84 ± 1.89 |
| Manganese | 0.49 ± 0.16 | 0.56 ± 0.18 | 0.52 ± 0.14 | 0.52 ± 0.16 |
| Chromium | 2.88 ± 0.72 | 3.12 ± 0.84 | 2.96 ± 0.68 | 2.99 ± 0.74 |
| Cobalt | 0.18 ± 0.08 | 0.22 ± 0.10 | 0.20 ± 0.06 | 0.20 ± 0.08 |
Mean concentrations of measured metals by formula type (milk-based n = 9; cereal-based n = 7; cereal mix-based n = 10)
Estimated Daily Intake and Recommended Dietary Allowance Comparison
| Age Group | Chromium EDI (μg/day) | Chromium RDA (μg/day) | Cr EDI as % RDA |
|---|---|---|---|
| 0–2 weeks | 15.2 | 0.2 | 7,600% |
| >2 weeks–4 months | 18.4 | 5.0 | 368% |
| 4–6 months | 19.2 | 5.0 | 384% |
| 6–12 months | 17.6 | 5.5 | 320% |
Estimated daily intake and percentage of RDA for chromium across four infant age groups, based on mean formula concentrations and age-appropriate consumption volumes
The critical finding is that chromium EDI exceeded the recommended dietary allowance across all age groups examined, with the most extreme exceedance in the 0–2 week group (7,600% of RDA). Iron, zinc, manganese, and cobalt concentrations were within expected ranges for infant nutrition.
Methods
Sampling: 26 commercially available infant formula samples (brand names not disclosed) purchased from retail outlets in Port Harcourt, Nigeria. Three formula categories: milk-based (n = 9), cereal-based (n = 7), cereal mix-based (n = 10).
Sample Preparation: Each formula sample was weighed, dissolved in ultrapure water at the manufacturer’s recommended reconstitution ratio, and prepared for atomic absorption spectrophotometry.
Analysis: Atomic Absorption Spectrophotometry (AAS) was used to measure iron, zinc, manganese, chromium, and cobalt concentrations. Results reported in μg/kg on a dry-weight basis.
EDI Calculation: Estimated Daily Intake was computed for four age-stratified groups using age-appropriate consumption volumes derived from WHO infant feeding recommendations and average formula consumption rates. Formula reconstitution factor (powder-to-liquid) applied to convert dry-weight measurements to as-consumed basis.
RDA Comparison: Measured EDI values were compared against official Recommended Dietary Allowance values for each age group from WHO and EFSA guidelines.
Implications
The finding that chromium exceeded the RDA across all age groups raises questions about the appropriateness of chromium levels in infant formulae marketed in Nigeria, particularly for very young infants (0–2 weeks) where the margin of safety is extremely narrow. This may reflect either contamination during processing, intentional fortification (unlikely for chromium), or elevated chromium levels in source ingredients. The study provides baseline data on trace metal profiles in Nigerian infant formulae but does not investigate the source of elevated chromium or its bioavailability from formula matrices.
Wiki Pages Updated
metals/chromium.md— added as A-tier source on infant formula contamination; documented EDI exceedance across all age groupsingredients/milk-based-infant-formula.md— routed as direct evidence on Cr concentrationsingredients/cereal-based-infant-formula.md— routed as direct evidence on Cr concentrationsproducts/infant-formula.md— routed as broad evidence on trace metal profile in Nigerian market
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## Page history
The five most recent substantive edits to this page. The full version history lives in [git](https://github.com/paleofoundation/heavymetalindex); when DOI minting comes online (see [[../docs/schemas/index.md|schema docs]]), each entry below will also link to a version-pinned DataCite DOI.
| Commit | Date | Description |
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| [ce3e07c](https://github.com/paleofoundation/heavymetalindex/commit/ce3e07c) | 2026-05-28 | activation \| Vercel DATACITE env slots set, curators.md filled with founder entry + six scoped reviewer invitations, peer-review onboarding playbook drafted |
| [51400b9](https://github.com/paleofoundation/heavymetalindex/commit/51400b9) | 2026-05-28 | audit-queue: gasparik2017-wild-boar-slovakia-metals audited-revised |
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