Assessment of Hazard Index and Incremental Life Cancer Risk Associated with Heavy Metals in the Soils

Abstract

The purpose of this review was to evaluate the hazard Index and Incremental life cancer risks associated with heavy metal contaminations of the soil for residents in the country. Many scientific articles have been accessible online in the Nigeria were evaluated for the estimation of [Hazard Index and Incremental Life Cancer Risk] for individual heavy metals. The heavy metals considered in this work are; [Lead (Pb), Copper (Cu), Iron (Fe), Manganese (Mn), Zinc (Zn), Chromium (Cr), and Cadmium (Cd)] The concentrations of these metals were obtained from the literature and modeled for, hazard index (HI), and carcinogenic risk (ILCR) via ingestion, inhalation, and dermal pathways for adults following the United State Environmental Protection Agency [USEPA] method. The hazard index for all the exposure pathways (ingestion, inhalation, and dermal contact) was found to be 21914, 1020.7, 580.8, 2.641, 0.272, 0.05165, 0.021, and 0.011[mg/kg/day], for Fe, Mn, Cr, Pb, Cu, Zn, Ni, and Cd respectively. United States EPA considered an overall hazard index value of 1.0 as an acceptable threshold below which no observable clinical effect was reported. In order of magnitude: Fe > Mn > Cr > Pb > Cu > Zn > Ni > Cd, Fe, Mn, and Cr have the highest Hazard Index in all the soil samples analyzed by different researchers in the country. In all the heavy metals reviewed, the Cd has the highest Incremental Life Cancer Risk followed by Cr, Pb, and Ni. This indicated that most of the areas are highly polluted with Cd, Cr, and Pb. Therefore, dwellers of the locations may likely be affected with cancer due to the ingestion, inhalation, and dermal contact with metals. The Overall results suggested that there is probable adverse health effects to an exposed population in all locations reviewed. Therefore, an effort will be made to prevent the transfer of heavy metals in the soil to the surrounding environment should be encouraged and soil remediation to further reduce the concentration of heavy metals needs to be effected immediately at root level.