Oguh CE, Chima UC, Wisdom OO, Ugwu CV, Tochi AP, Blessing OC, Kelechi EG
This study investigate the bioaccumulation of potentially toxic elements build-up in vegetables Amaranthus cruentus, and Corchorus olitorius grown with water treatment sludge and the human health risk associated with their consumption. Soil and vegetables samples were collected from farms with sludge and other samples from a farm where there were no sludge served as control. The soil samples were collected at random and analyzed for physicochemical properties, using a standard method and concentrations of the toxic elements both in soils and vegetables, As, Cd, Cr, Cu, Hg and Pb were analyze using Atomic Absorption Spectroscopy (AAS). The potential risk from the consumption of these vegetables was assessed using standard methods. The result showed a significant increase in physicochemical properties on soil with sludge over the control without sludge. The mean concentration of Cd and Hg in AC soil with sludge (3.61 and 3.28 mg/kg) and CO soil with sludge (3.27 and 3.39 mg/kg) respectively, were above the WHO/FAO permissible limits of 3.0 mg/kg Cd and 2.0 mg/kg Hg for soil except for other metals and the control soil samples which recorded a mean value that was below the permissible limit. The mean concentrations of As, Cd, Cr, Cu, Hg and Pb recorded in AC with sludge were 2.80, 2.00, 3.72, 4.08, 3.54 and 3.61 mg/kg respectively while CO with sludge were 2.89, 2.00, 3.64, 4.26, 3.48 and 3.09 mg/kg respectively which were above the WHO/FAO permissible limit of 0.5, 0.20, 0.3, 3.0, 0.1 and 0.3 mg/kg respectively for edible vegetables and are significantly different (p<0.05) from the controls. The mean values recorded at all control sites were below the FAO/WHO acceptable value except Cr which was above the WHO/FAO permissible limit of 0.3 mg/kg for edible plants. The HQ and HI shows that there is no harmful effect on the consumption of the vegetables since the values obtain were not greater than>1. The study concludes that soil around water treatment sludge and vegetables grown with water treatment sludge can bio accumulate toxic substance such as heavy metals which pose health risk from the consumption.
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