ABSTRACT

This study aimed to assess the human health hazards, pollution indices and potential ecological risks of heavy metals from waste sites established in Umuahia residential vicinity. The heavy metals analyzed using Atomic Absorption Spectrometer (AAS) were Chromium (Cr), Lead (Pb), Cadmium (Cd), Nickel (Ni). Copper (Cu) and Zinc (Zn). A total of40 soil samples were collected from waste sites in two residential estates (Ehimiri and Umuobia) located in the urban and suburb areas of Umuahia Abia slate, Nigeria. Results revealed a trend in concentrations of the heavy metals for both sites in the following order: Cu > Ni > Zn > Cr > Cd > Pb, indicating absence of industrial contributions to the urban waste site. The concentrations of heavy metals in the studied waste sites were much lower than the background values employed, except Cd which was slightly higher. The contamination factor (CF) indices for Pb, Cr, Cu, Ni and Zn were less than 1 for both sites, signifying a low contamination scenario. The contamination factor for Cd (6 > CF) for both sites indicated a very high contamination status. The estimated degree of contamination (Cdeg) was less than the lower threshold of 8.0 (Cdeg = 6.8, urban; Cdeg = 7.3, rural) denoting a low degree of contamination. Cd was the highest contributor to ecological risk with Er index value of 184.2 among measured heavy metals. The overall potential ecological risk index for urban and a rural sites are 187.1 and 196.1 respectively, classifying the sites as moderate risk. The overall noncarcinogcnic hazard index values (III) for adult and child in urban and rural soils are 0.00248, 0.0198 and 0.0028, 0.0223 respectively, which arc below the acceptable limit (HI < 1), indicating that the exposed residents arc unlikely to experience any apparent adverse health hazards. However, children arc more susceptible to non-carcinogcnic hazards than adults in the study areas.