Ametepey et al. 2018 — Heavy metals in market vegetables from Tamale, Ghana
Ametepey et al. measured Cd, Pb, Cr, Ni, Mn, Fe, Zn, and Cu in five vegetables (lettuce, spring onion, tomato, garden egg/eggplant, and kontomire/cocoyam leaf) purchased from three markets in Tamale, northern Ghana. Fifteen samples per vegetable were analyzed by AAS. The study is relevant to geographic variance in heavy metals in vegetables from West Africa, a region where wastewater irrigation, mining-area soils, and use of contaminated water for crop production are documented drivers of elevated metal concentrations. Cd and Pb were detected above WHO/FAO food safety limits in multiple samples, particularly in leafy vegetables.
Key numbers
- 5 vegetables × 3 markets × 5 replicates = 75 samples
- Cd concentrations: lettuce and kontomire showed highest Cd; range approximately 0.01–0.18 mg/kg fresh weight; some samples exceeded the Codex maximum of 0.05 mg/kg for leafy vegetables
- Pb: detectable in all vegetables; lettuce highest (approximately 0.1–0.4 mg/kg fresh weight); some samples approached or exceeded WHO/FAO limits
- Cr: detected in most samples; range approximately 0.01–0.15 mg/kg fresh weight
- Ni: detected in lettuce and kontomire at levels up to 0.3 mg/kg fresh weight
- Analysis by flame AAS (FAAS); wet weight basis
Methods (brief)
FAAS; 5 vegetable types; 3 markets in Tamale, Ghana; 15 samples per vegetable; wet digestion with HNO₃/HClO₄; fresh weight basis; QC with certified reference material.
Implications
Certification: Provides West African baseline data for vegetable Cd and Pb. Geographic variance between Ghana-sourced leafy vegetables and European-grown equivalents is substantial. Courses: West African market vegetables are a meaningful Cd and Pb exposure route for local populations; irrigated vegetables in urban markets are higher-risk than rurally grown. App: Geographic origin flag for leafy vegetables sourced from West Africa should carry elevated Cd/Pb risk signals relative to EU or US-grown equivalents.