This study was carried out in order to determine the concentrations of some heavy metals namely; lead, cadmium, nickel and zinc in selected vegetables. Cucumber (Cucumis sativus), watermelon (Cucurbita lanatus), tomato (Solanum lycopersicum) and pepper (Capsicum annuum), brought from Kano state as well as those cultivated in Edo state, Nigeria. A total of 25 samples consisting of four different vegetables were each purchased from two major markets where vegetables from Kano state are sold in Benin City as well as those cultivated in Benin City, Edo state, Nigeria. Edible portions of the samples were used for analysis. Samples for analysis were dried using the oven dry method at 105 oC for 24 hours and later ground. About 1.0g of the samples were each weighed and digested in a mixture of 10 ml Nitric–Perchloric acid in a 250 ml Kjeidahl flask under a fume hood. The content was mixed and heated gently at 120 – 200 °C for about 45 minutes on a hot plate. Heavy metals were present in all the vegetables analysed at various levels. Cadmium concentration ranges between 0.02 – 0.47 mg/kg, Lead was within the range of 0.03 – 11.12 mg/kg, zinc concentration ranges between 0.15 – 73.69 mg/kg, and nickel concentration ranges between 0.07 – 35.54 mg/kg respectively in all the vegetables from the two states. Cadmium and Lead were observed to be higher than that of the maximum permissible limit (MPL) stipulated by the World Health Organisation (WHO).
Key Words: Vegetables, Toxicity, Heavy metals, Assessment