Contamination levels and health risk assessment of heavy metals in food crops in Ishiagu area, lower Benue trough South-eastern Nigeria

The assessment of health risk associated with the consumption food crops grown in the Ishiagu mining area has been carried out. Mining activities in the area have consequently increased the concentration of heavy metals in the arable soils. Uptake by plants can lead to bioaccumulation which increases the health risk of inhabitants of the community. In this study, forty (40) samples of leaves of Musa paradisiaca, Carica papaya, Abelmoschus esculentus, Telfairia occidentalis, Phaseolus vulgaris, Manihot esculenta, Colocasia esculenta and tubers ( Solanum tuberosum, Dioscorea alata, Dioscorea cayenensis, M. esculenta, Dioscorea rotundata and C. esculenta ) were collected across the area and analysed for heavy metals using atomic absorption spectrophotometric method. Health risk indices were applied to evaluate the effect on humans. Result show that the metal accumulations follow Hg > Cd > Mn > Pb > Cu > Co > As > Cr > Zn > Mo and Hg > Cd > Pb > Mn > Co > Cu > Cr for leaves and root/tubers, respectively. The DIM, HRI and THQ were analysed for adult and children, respectively, where children were found to be more vulnerable to these associated risks. DIM, HRI and THQ data revealed Hg, Cd and Pb as the most potent contaminants in the area with risk quotient of following order Hg > Cd > Pb. Tubers showed higher frequency of the presence of these metals, whereas leaves accumulate higher quantity/concentration of them. Mo and Zn were BDL in the crops sampled in the study area except for leave of M. esculenta from LSI 1 with Zn 42.15 mg/kg. There are diverse degrees of health risk that could be incurred through consumption of these food crops resulting from Hg, Cd and Pb which has HRI and THQ > 1.