Assessment of heavy metal contents in farm produce around Ewekoro and its health implications on consumers

Abstract

This study was conducted to assess the risk of exposure to thirteen (13) heavy metals from food products obtained from cassava tubers grown in the limestone mining area of Ewekoro, Ogun State in Nigeria. Four (4) samples each of soil and cassava tubers were collected at three different sites for this study. The first two sample collection sites were at 150 m and 300 m from the mining site while the third or the control samples were collected at a distance of 25 km far away from the mining activities. The collected samples were analyzed by the use of Inductively Coupled Plasma-Optical Emission Spectrometry. The concentration average of Fe, Mg, Na, Ag, As, Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn ranged from 2.00–1284.96 to 0.0098–646.31 mg/kg for both soil and cassava tubers, respectively at site 1, which was far higher than 0.26–622.01 and 0.90–514.35 and 0.07–688.37 and 0.07–371.74 mg/kg reported in both soil and cassava tuber samples at the other 2 locations. The transfer factor from the soil to cassava tuber for Fe, Mg, Ag, As, Cd, Cu, Co, Mn and Pb were observed to be < 1. While Na, Cr, Ni and Zn had transfer factor > 1. The estimated average daily intake at site 1 for both adults and children were 0.46 and 1.69 mg kg−1 bw−1 d−1, respectively. These values were far higher than the results noted at sites 2 and 3 for both adults and children. Similarly, the Risk Index for both adults and children at site 1 were reported to be 7.01 and 25.42, which were higher than the values noticed at the other 2 sites. Therefore, it can be concluded that although the concentrations of these heavy metals were higher than the internationally recommended standard, the EADI and RI revealed that children are at higher risk of exposure to the heavy metal contents from food products derived from cassava in the study area.