Abstract

The levels of some heavy metals (Cr, Mn, Fe, Cu, Ni, Cd, Hg, As, Pb) were detected using Atomic Absorption Spectroscopy (AAS). Vegetable samples of tomatoes (Solanum  lycopersicum), spinach (Spinacia oleracea), roselle (Hibiscus sabdariffa), onion (Allium cepa) and cucumber (Cucumis sativus) from five different agricultural locations (S1 – S5) around Gubi Dam, Bauchi State. The concentration of the selected heavy metals exceeded the maximum permissible limits as specified by FAO/WHO with exception the of Hg and As. Result on the average daily intake (ADI) were below the provisional tolerance daily intake for (Cr 0.5-0.2, Mn 20, Fe 0.048, Cu 3, Ni 1.4, Cd 0.0003, Hg 0.06, As 0.13 and Pb 0214) mg/kg, in all the vegetable samples while the values of hazard quotient (HQ) were also lower than the threshold of 1 mg/kgd-1. However, Cr concentration in spinach samples from point S1 agricultural location recorded the highest value of 1.19E + 00 mg/kgd-1 than the threshold of 1 mg/kgd-1. Results from the hazard index (HI) shows that consumption of the vegetables from the study area might result to potential health risks with respect to Cd and Pb. The cancer risk (CR) assessment shows the probability of developing cancer-related illness with respect to the Cd, Ni and Cr. Based on the above results, the study concludes that the agricultural locations within Gubi Dam are exposed to potentially toxic heavy metals; thus, relevant agencies should be involved in monitoring the study environment.

Key words: Risk assessment, vegetables, heavy metals contamination, Gubi Dam, Nigeria.