Alemu et al. 2022 — Metals in wheat flour, Ethiopia
This study measured concentrations of Fe, Mn, Cu, Zn, Ni, Cd, and Pb in nine samples of wheat flour purchased from Ethiopian markets, using flame atomic absorption spectrometry (FAAS). The primary food-safety interest is in Ni, Cd, and Pb. Ni ranged from 0.154 to 0.854 mg/kg (mean not reported per element; ranges are for Ethiopian samples), Cd ranged from 0.0411 to 0.216 mg/kg, and Pb was below the detection limit (LOD) of 0.043 mg/kg across all Ethiopian samples. Hazard quotients (HQ) for all metals were below 1.0, and the hazard index (HI) summing across metals was also below 1.0, suggesting no acute non-carcinogenic risk under the consumption assumptions used. Comparison with Indian wheat flour from the literature showed broadly similar Ni and Cd ranges.
Key numbers
- n = 9 Ethiopian wheat flour samples; analyzed by FAAS.
- Ni: 0.154–0.854 mg/kg (wet weight assumed, basis not explicitly stated).
- Cd: 0.0411–0.216 mg/kg.
- Pb: <0.043 mg/kg (all below LOD of 0.043 mg/kg).
- HQ (all metals individually): <1.0.
- HI (sum of HQs): <1.0.
- LOD for Pb: 0.043 mg/kg.
- Regulatory comparison made against FAO/WHO and Ethiopian Food, Medicine and Health Care Administration and Control Authority (EFMHACA) limits.
Methods (brief)
FAAS (flame atomic absorption spectrometry); samples dry-ashed or acid-digested (method details in paper). Total metals reported; no speciation. Sample size is small (n = 9), which limits confidence estimates. All Pb values below LOD — results reported as censored.
Implications
Certification: Cd at up to 0.216 mg/kg in Ethiopian wheat flour is within the range of concern for frequent consumers; below EU 0.2 mg/kg limit for cereals but approaching or exceeding it. Ni at up to 0.854 mg/kg relevant for nickel-sensitive consumers. The Pb censoring at 0.043 mg/kg is a relatively high LOD that may miss meaningful Pb contamination. Courses: Illustrates detection/non-detection handling and the importance of LOD in interpreting food surveillance data. App: Wheat flour contamination profile — Cd and Ni both in detectable ranges; Pb data gap due to LOD.