Overview
Larsen and colleagues sampled maize and millet flour at village corn mills in 10 communities of the Tolon District, Ghana, in March 2019, and compared it with the same grain pounded by hand. Six metals were measured by AAS. Lead was the highest metal in both flours and about eleven times the Codex value the authors used, while hand-pounded controls also held lead, so the mill plates were not the only source.
Key numbers
- Milled maize: lead 2.2177 ± 0.0534 mg/kg; nickel 0.9502 mg/kg; chromium 0.4359 mg/kg (Table 2, p. 4208).
- Milled millet: lead 2.2780 ± 0.0221 mg/kg (Table 2); the text gives 2.29 mg/kg.
- Pounded maize control: lead 2.26 mg/kg, slightly above the milled flour (text, p. 4209).
Methods (brief)
Samples were briefly oven-dried, digested in sulfuric acid with catalyst tablets and read on a Varian Spectra 220 FS AAS. No detection limits, recoveries or reference materials are reported. Cadmium, arsenic and mercury were not measured.
Evidence Fitness
Ten samples per flour type with weak reported QA; the basis is not stated, and the lead values are very uniform across communities. The paper measures maize flour, not a finished tortilla or chip: it is a proxy for corn-tortilla and tortilla-chips, which are not linked.