Levels of Heavy Metals and Potential Human Health Risks via Consumption of Leafy Vegetables Purchased in Popular Local Market in Lagos, Nigeria

The increase in consumption of leafy vegetables and their inclusion in daily diet have necessitated vegetable farming throughout the year on very busy road-side farms and gardens and conventional and non-conventional farming areas without consideration for potential risk to health of the consumers. Therefore, the objective of this study is to determine the levels of copper, zinc, chromium and nickel and evaluate the potential health risks to human exposure via the consumption of Celosia argentea, Talinum triangulare and Vernonia amygdalina leafy vegetables purchased in a popular local market in Lagos, Nigeria using ICP-MS after complete dissolution by mixed-acid digestion , The results indicated the presence of Cu, Cr, Zn and Ni with ranges of 6.50 ±0.37 - 18.98±0.31 mg/g, 1.33±0.03 - 7.30±0.19 mg/g, 1.00±0.06 - 3.90±0.60 mg/g and 0.49±0.02 - 2.01±0.06 mg/g respectively. Cu had the highest significant concentrations in V. amygdalina among the vegetables and with the highest concentrations at Site A. The concentrations of all trace metals in the leafy vegetables exceeded the stipulated WHO/FAO permissible standards. Overall, the hazard quotients for trace metals were low, indicating that they may not pose a health risk to the populace through consumption of the leafy vegetables, however, the continuous consumption may pose a serious health risk owing to values recorded that were above the acceptable limit set by WHO.