LEAD AND CADMIUM CONTENT OF COMMONLY CONSUMED LEAFY VEGETABLES IN OPEN MARKETS IN IBADAN AND WARRI, NIGERIA

Abstract

Leafy vegetables are the most predominant constituents of Nigerian cuisine and are essential sources of vitamins and minerals. Urban activities in cities like Warri and Ibadan may elevate heavy metal (HM) concentrations in the environment. Prolonged consumption of Lead (Pb) and Cadmium (Cd) contaminated vegetables may lead to health problems such as nervous disorders, kidney diseases and impaired cerebral functions. However, the possibilities of contamination of leafy vegetables with Lead and Cadmium have not been well documented in Warri and lbadan. This study was therefore conducted to determine levels of lead and cadmium in leafy vegetables in the two cities. This study was a cross-sectional survey involving three randomly selected major markets each from Warri (Mainmarket, Makaiva and Ogbeijo) and lbadan (Bodija, Gate and Oje). Vegetables identified through the questionnaire as mostly consumed were selected and replicate samples were pooled to make up a composite that was used for the analysis. Sample collection was done in the morning (8-9 a.m.) and evening (4-5 p.m) for three non-consecutive days. Edible leafy portions of the samples were picked, oven dried at 105°C, ground and analysed for Pb and Cd using Atomic Absorption Spectrophotometer. Results were compared with WHO/FAO acceptable limits for Pb (0.3 mg/kg) and Cd (0.2 mg/kg) in food. Data were analysed using descriptive statistics and t-test at p=0.05. Commonly consumed vegetables in the study areas were Telfairia occidentalis (Ugu) and Talinum triangulare (Waterleaf). Concentrations of HMs found in vegetables were Talinum triangulare (Tb=0.42±0.19 mg/kg; Cd=0.54±0.19 mg/kg) and Telfairia occidentalis (Pb=0.38±0.13 mg/kg; Cd=0.39±0.18 mg/kg) in Warri while the values in lbadan were Talinum triangulare (Pb=0.42±0.16 mg/kg, Cd=0.28±0.12 mg/kg) and Telfairia occidentalis (Pb=0.42±0.19 mg/kg, Cd=0.25±0.15 mg/kg). Among the vegetables sampled, acceptable limits for Pb and Cd in food were exceeded in both Warri and lbadan. Cadmium concentration among vegetables in Warri (0.46±0.20 mg/kg) was significantly higher than Ibadan (0.26±0.16 mg/kg). There was no significant difference in the Pb concentration in the two cities. Talinum triangulare consistently showed higher metal concentration in both study areas for both Pb and Cd. Concentrations of Lead and Cadmium in leafy vegetables in lbadan and Warri exceeded safe limits, thus indicating excessive contamination that could be considered a serious health hazard. Periodic assessment by regulatory agencies should be carried out to identify sources of heavy metal contamination and provide abating strategies for the promotion of food safety.