E.T. Aisien

Urban vegetable cultivation in Benin Metropolis contributes significantly to household nutrition but faces contamination risks from heavy metals. This study assessed heavy metal concentrations in vegetables grown in polluted areas (Ibiwe axis) and less contaminated zones (Oko community). A comparative cross-sectional design was adopted, and samples of Talinum triangulare (water leaf), Ocimum gratissimum (scent leaf), Vernonia amygdalina (bitter leaf) and
Telfairia occidentalis (pumpkin leaf) were collected from dumpsites, mechanic workshops and residential gardens. Following acid digestion, cadmium (Cd), lead (Pb), nickel (Ni), copper (Cu) and zinc (Zn) levels were determined using Atomic Absorption Spectrophotometry. Independent sample t-tests (p < 0.05) showed significantly higher concentrations of Cd, Zn and Ni in vegetables from polluted sites. For instance, Cd in water leaf was 0.017 ± 0.001 mg/kg in
polluted sites compared with 0.004 ± 0.001 mg/kg in cleaner areas, while Zn in scent leaf reached 0.080 ± 0.001 mg/kg against 0.002 ± 0.001 mg/kg. Bitter leaf showed the highest accumulation across all metals, particularly Ni (p = 0.001). Although overall concentrations were below WHO/FAO limits, polluted-site vegetables contained 4–40 times more metals than those from unpolluted zones. These findings highlight that cultivation location strongly influences
metal accumulation and emphasize the need for stricter environmental controls and regular
monitoring to safeguard public health.

Vegetables are consumed in both the developing and developed countries of the world due to their high nutritive values, however they also contain some high levels of toxic substances including metals.This study assessed the comparative concentrations of selected heavy metals:cadmium (Cd), lead (Pb), nickel (Ni), zinc (Zn), and copper (Cu) in four commonly consumed leafy vegetables: fluted pumpkin (Telfairia occidentalis), bitter leaf (Vernonia amygdalina), water leaf (Talinum triangulare), and scent leaf (Ocimum gratissimum) cultivated in polluted (Oluku) and unpolluted (Iyowa) sites in Benin City, Edo State, Nigeria. Samples were analysed using Atomic Absorption Spectrophotometry (AAS), and results were compared with FAO/WHO permissible limits. The concentrations of all heavy metals were below recommended safety thresholds, with the general trend of accumulation being polluted site > unpolluted site. Statistical analysis (p < 0.05) revealed significant variations for some metals, particularly Zn, Cd, and Cu, across the two locations. Bitter leaf and scent leaf exhibited higher tendencies for metal accumulation compared to other vegetables. Although all concentrations were within safe limits, continuous cultivation near polluted areas may lead to long-term contamination risks. The findings highlight the influence of anthropogenic activities such as waste disposal and vehicular emissions on metal uptake in vegetables and underscore the need for regular environmental monitoring, improved waste management, and public awareness to ensure food safety