DIETARY INTAKE AND HEALTH RISK FROM POTENTIALLY TOXIC ELEMENTS IN EDIBLE CROPS FROM SOILS DEVELOPED ON SHALE BEDROCK, SOUTH EASTERN, NIGERIA

A total of about 160 edible crop plants including vegetables, fruits and food crops grown on soils derived from shales were harvested, prepared, digested and analysed by means of Inductive Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). This was to investigate the levels of potentially toxic trace elements (PTE), evaluate the daily intake and health risk of the PTE in these staple crop plants in parts of south eastern Nigeria and neighbouring Cameroon. The results revealed that the mean concentrations of PTE in the plants is in the order, Fe>Al>Mn>Zn>Sr>Ba>B>Cu>Pb>Co>Cd with the vegetables showing the highest level of concentration. The mean concentration of Fe, Sr, Mn and Pb are above the range set by some regulatory bodies while the estimated daily intakes (EDI) are within these ranges. The target health quotient (THQ) of Cd (1.092- 4.007) and Pb (1.926- 7.064) for Colocasia escalentum vegetable (cocoyam leaves), Pb for Amanrantus hybridus, known locally as green (2.031-0.745) and Telfaira occidentalis (1.573 - 0.577) were above the FAO/WHO allowable limits. The hazard index (HI) were above 1 for Colocasia escalentum vegetable (2.084-17.001), Amanrantus hybridus (2.368– 1.282), Telfaira occidentalis (1.887-1.220), Ananas sativa (0.146-1.264) and Oryza sativa shoots ( 0.155–1.126). Cd and Pb are related to many health problem/biochemical defects for children and adults such as renal damages, abnormal urinary excretion of protein and toxicity of nervous system. The HI above 1 for some of these crop plants showed that humans may be exposed or associated to health risks through the consumption of these crop plants. Thus spatial assessment of the health risk of the populace via food consumption in the shale region as well as the soil-plant transfer factor is recommended for further studies.