Non-carcinogenic and Carcinogenic Risk Potentials of metals Exposure from Vegetables Grown in Sharada Industrial Area Kano, Nigeria

Chemical elements such as heavy metals significantly functions as trace elements but their bio-toxicity to human biochemical process poses a great concern for public health. The human exposure to heavy metals via food chain has been a documented risk factor for cancer development and other health-related implications. The levels of some carcinogenic (Chromium Cr; Cadmium Cd and Lead Pb) and non carcinogenic (Nickel Ni; Cobalt Co; Copper Cu and Zinc Zn) heavy metals in vegetables (Onion, Drumstick, Lettuce, Okra, and Carrot) grown in Sharada industrial area, Kano were evaluated. The human health risk implications were also determined by estimating the daily metal consumption, and calculating non cancer and cancer risks (Incremental Life Cancer Risk, ILCR and Target Hazard Quotients) using US-EPA probabilistic health risk assessment (US-EPA risk predicting model). The mean concentration of lead (Pb) ranged from 11.21±0.55 µg/g in Okra to 16.84±0.86 µg/g in onion. Carrot had the highest concentration of chromium (65.10±3.20 µg/g). The levels of various heavy metals found in the studied vegetables/plants differ generally with plant species. The predictive values of human developing cancer disease from the incessant intake of studied plant/vegetables was found higher than the standard threshold risk boundary set by US-EPA, (>10-4) for Cr, Pb, and Cd. The non cancer health risk values also predicted Pb, Cr and Cd as the dominant metal contaminants of the vegetables with the Health Risk Index greater than one (>1), while Ni, Co, and Zn showed safe quotients. Among the studied vegetables/plants, carrot has predicatively, the highest cancer risk (∑ILCR 1.25 with chromium contributing 92%), followed by lettuce, onion, Moringa oleifera, and okra (Carrot> Lettuce > Onion > Moringa > Okra). It is, therefore, suggests that the industrial area is unsafe for irrigation due to the heavy metals pollutions of the soil and irrigation water and the risk of high consumption of vegetables grown exposes the population to incremental cancer risks potential among others.