Summary
This Scientific Reports study analyzed proximate composition and heavy metal content in 8 locally produced baby milk samples and 12 infant formula samples purchased from Umuahia, Nigeria. Lead, cadmium, nickel, and chromium were measured by atomic absorption spectrometry (AAS) after aqua-regia digestion. Target hazard quotient (THQ) and hazard index (HI) risk assessment was performed using EPA IRIS reference doses. The paper reports that only cadmium and chromium (less than 0.2 to 0.3 mg/kg) posed health risk. Baby milk was generally higher in mineral content than infant formula. The study is relevant as market-surveillance evidence from Sub-Saharan Africa.
Key numbers
Heavy metal concentrations, mg/kg (Table footnote in abstract; values are ranges across samples):
Baby Milk (BM, n=8 samples; Table 1 of full text):
- Lead (Pb): range 0.06-0.21 mg/kg (60-210 µg/kg)
- Cadmium (Cd): range 0.01-0.04 mg/kg (10-40 µg/kg); reported as posing health risk
- Nickel (Ni): range 0.03-0.26 mg/kg (30-260 µg/kg)
- Chromium (Cr): range 0.000-0.006 mg/kg (0-6 µg/kg); reported as posing health risk (above 0.2 mg/kg threshold cited)
Infant Formula (IF, n=12 samples; Table 1 of full text):
- Lead (Pb): range 0.00-0.21 mg/kg (0-210 µg/kg)
- Cadmium (Cd): range 0.00-0.04 mg/kg (0-40 µg/kg)
- Nickel (Ni): range 0.23-0.83 mg/kg (230-830 µg/kg)
- Chromium (Cr): range 0.000-0.006 mg/kg (0-6 µg/kg)
Risk assessment:
- THQ < 1 considered safe; THQ > 1 indicates potential health risk
- HI = sum of THQs across metals
- Reference doses used: Cd 0.001, Cr 0.003, Pb 0.0035 mg/kg/day (US EPA IRIS)
- Average body weight assumed 5 kg for all infants; average daily intake 0.1 kg/day
- Results: only Cd and Cr exceeded THQ of 1 in some samples
Proximate composition: Baby Milk had higher carbohydrate and lower protein content; Infant Formula had higher protein. All moisture contents were within acceptable ranges. Infant Formula moisture was above 5% (Codex limit), which the authors flag as a potential spoilage concern.
Methods (brief)
Cross-sectional market survey in Umuahia, Abia State, Nigeria. One sample per brand purchased at different shop locations. Samples stored in refrigerator until analysis. Heavy metals determined by acid digestion with 20 mL aqua-regia (HCl:HNO3, 3:1 ratio) at 90 degrees C for 2 h, filtered and diluted to 100 mL, analyzed by atomic absorption spectrophotometry (Perkin Elmer, Analyst Model 400). THQ and HI calculated per EPA IRIS framework. Statistical analysis by ANOVA with Duncan multiple range test at p < 0.05.
Limitations
Small sample size (8 BM + 12 IF). Single-city sampling frame (Umuahia). The study does not report speciated arsenic (tAs not measured), methylmercury (not measured), or aluminum. The analytical method (AAS with aqua-regia open vessel digestion) has lower precision than ICP-MS microwave digestion for some metals. Only locally produced brands are included; imported formula brands available in Nigeria are not represented. Nickel and chromium THQ interpretation is limited because total Cr (not Cr-VI) is measured and the oral hexavalent chromium (Cr-VI) RfD is not applicable to total Cr.
Implications
- Certification: Useful as African-market occurrence context for Pb, Cd, Ni in infant formula. Lead and cadmium values fall within global ranges. Nickel range 230-830 µg/kg in IF is notably high relative to Polish market data (median 0, max 17 µg/kg) and may reflect local raw material or water quality differences.
- Courses: Useful example of market surveillance in a developing-country context and of how analytical method limitations affect comparison across studies.
- App: Adds African-market occurrence signal for Pb, Cd, Ni in infant formula powder.
- Microbiome: No direct microbiome endpoint.
Provenance notes
Open-access CC BY-NC-ND article. PDF retrieved from PMC (PMC13129085). SHA256 verified against MANIFEST.csv for HMI-PROD-ready-to-feed-formula-1.
Update history
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