Abstract

This study was conducted to determine the mean concentration of some trace metals in soil and waterleaf (Talinum triangulare) harvested from some abandoned and active waste dumpsites and their control sites in Uyo designated as SP1, SP2, SP3, SP4 and SP5 using flame atomic absorption spectrophotometer. The transfer factor of these metals and the human health risk via the consumption of the above plant was assessed using standard models proposed by USEPA. Measureable amount of the trace metals namely: Lead (Pb), Cadmium (Cd), Iron (Fe), Copper (Cu), and Zn (Zn) was observed in this study. The range for the result in the soil samples at the dumpsites and the control sites were as follows: Pb (0.160-11.286), Cd (0.607-21.098), Zn (11.070-44.346), Fe(1.925-45.876), Cu (0.768- 55.071) while the range for waterleaf was Pb (0.052-3.617), Cd ( 0.140- 2.060), Zn (0.118-12.346), Fe( 0.193-13.372), Cu (0.163-10.267). The mean concentrations of the investigated metals in the soil and plant samples were higher at the dumpsite compared to their control sites (P < 0.05). The concentrations of the investigated trace metals in soil at all the dumpsites were lower than the WHO standard except Cd in all the locations and Cu in two locations. Also, the mean concentration of Fe, Cu and Zn in waterleaf was higher than the standard stipulated by WHO/ FAO in two locations while the concentrations of Pb and Cd were higher than the above standard in most of the study locations. The transfer factor for all the metals at the dumpsite was greater than one except Pb, Cu, Cd at SP1 while the transfer factor for all the studied metals was lower than one at the control sites. The result for estimated daily intake via the consumption of water leaf for the toxic metals (Pb and Cd) was higher than the oral reference dose while the EDI for the essential trace metals was less the oral reference dose. Also, the target hazard quotient for the toxic metals was higher than one while that of the essential trace metals was less than one. The hazard index which indicates the cumulative target hazard quotient was greater than one in all the study locations. Therefore, the consumption of Talinum triangulare harvested from abandoned and active waste dumpsites in Uyo Urban should be discouraged to avoid Pb and Cd toxicity.