Heavy Metal Contamination, Source Apportionment, and Probabilistic Health Risk Assessment of Street-Vended Roasted Plantain in Benin City, Nigeria: Children as a Vulnerable Population

Street-vended roasted plantain (Musa paradisiaca L.), locally called boli, is widely consumed in urban Nigeria, yet its open-air charcoal preparation exposes it to multi-source heavy metal contamination. This study integrated contamination characterisation, source apportionment, and probabilistic health risk assessment of iron, zinc, copper, and lead in roasted plantain from ten urban microenvironments in Benin City, Edo State. Five independent vendor samples were collected per site (n = 50), wet-digested in concentrated sulphuric and nitric acids, and analysed by flame atomic absorption spectrophotometry, with quality assurance against the certified plant-matrix reference material NIST SRM 1547 (Peach Leaves). Mean concentrations decreased in the order Fe (6.89–9.13 mg/kg) > Zn (2.27–4.68 mg/kg) > Cu (0.91–2.67 mg/kg) > Pb (0.016–0.049 mg/kg). All lead values fell below the method quantification limit and are treated as provisional throughout, as is every lead-derived estimate. Copper exceeded the FAO/WHO limit (0.5 mg/kg) at all ten sites, peaking at 2.67 mg/kg at New Benin. Multivariate source apportionment resolved two sources explaining 78.7% of variance: an iron–zinc–copper industrial–commercial factor and a provisional lead-associated vehicular factor. Children showed approximately four-fold higher exposure and risk than adults. Non-carcinogenic risk was below the threshold of concern for adults at every location. For children, on a dry-weight basis, it exceeded the threshold at New Benin under the deterministic model, and Monte Carlo simulation extended exceedance to three further locations; expressed on a fresh-weight basis these exceedances are conditional on the moisture content of the consumed product, which was not determined. Lead-related carcinogenic risk fell within the acceptable range at all sites on a provisional basis. These findings identify children as the priority population and New Benin as the principal intervention node for street-food safety.