HEAVY METALS CONTAMINATION, POLLUTION INDICES AND HEALTH RISK ASSESSMENT OF SOILS IN DUMPSITES WITHIN THE VICINITY OF UNIVERSITY OF PORT HARCOURT, NIGERIA.docx

This study investigated the levels of Lead(Pb), Zinc (Zn), Cadmium (Cd), Manganese (Mn), Chromium (Cr), Nickel (Ni), Arsenic (As) and Copper (Cu) in soils from four selected dumpsites in the vicinity of the University of Port Harcourt, East-west Road, Choba, Rivers State, Nigeria. Analysis of metals was done by wet digestion and atomic absorption spectroscopy, and the concentrations were found to fall within the following range; Zn (74.54–122.42mg/kg), Cr (28.76-42.17mg/kg), Ni (15.71-24.95mg/kg), Cu (13.62-23.17mg/kg), Mn (6.15-10.74mg/kg), Pb (4.87-10.32mg/kg), Cd (2.79-5.15mg/kg) and As (0.35-0.85mg/kg) for the four samples respectively, showing their occurrence to be in the order Zn&gt;Cr&gt;Ni&gt;Cu&gt;Mn&gt;Pb&gt;Cd&gt;As. The results were further evaluated with some pollution indices (Geo-accumulation Index (Igeo), Contamination factor (CF), Pollution Load Index (PLI), Ecological Risk factor (Erⁱ), and The Potential Ecological Risk Index (R_i)). The average daily intakes (ADI) of metals were below the reference dose (RfD) recommended by World Health Organisation (WHO) showing little or no risk from heavy metals is associated with the routes of exposure. Estimation of pollution indices showed soils from dumpsites were extremely polluted with cadmium. Specifically, Igeo results graded soil samples as unpolluted to moderately polluted (Ni and Cr in sites B and C), with Cd being observed to be highly polluted in all the sample areas studied. The same trend was also observed for the CF, which ranged from very slightly contaminated to moderately polluted in the following order Mni values were below 40, showing a low ecological risk posed by the other metals save Cd which had a moderate (sites B and C) to high ecological risk (sites A and D). R_i values (113- 200) is a presentation of a low to moderate potential ecological risk posed by the metals in all sample locations, with cadmium contributing 96.38–96.47% of the entire potential ecological risk. Measured concentrations of these metals used to calculate the health risk for adult and children population, showed that the average daily intakes (ADI) of metals were below the reference dose recommended by World Health Organisation (WHO) showing that little or no risk from heavy metals in these sites is associated with the routes of exposure. However, the ADI of Cu in control site was greater than the RfD by WHO standards thus calls for concern for non-carcinogenic health complications. The Hazard index (HI) value for adult and child population, via exposure was &lt; 1, indicating low non-carcinogenic effects to the population. However, the Hazard Index value for the population in the control site was &gt;1, indicating a high non-carcinogenic risk to adult and children exposed in the area. The carcinogenic risk for all metals in this study was within the cancer safe limits, and poses no potential to cause carcinogenic health risk.<br><br>