Oral Ingestion Risks of Heavy Metal Accumulation at Top Soils of Automobile Workshops in Owerri Capital City of Imo State, Nigeria

Abstract This investigation was carried out to assess the heavy metal concentrations and health risks associated with automobile workshops in Owerri Metropolis. Using an Atomic Absorption Spectrophotometer, soil samples from Orji Mechanic Village (OMV), Naze Mechanic Village (NMV), New Market Automobile Workshops (NMAV), Matrix Mechanic Yard (MMY) and Alvan Mechanic Yard (AMY) were assayed for Silver (Ag), Cobalt (Co), Nickel (Ni), Mercury (Hg), Lead (Pb), Arsenic (As), Chromium (Cr) and Cadmium (Cd) concentrations. The result showed that at majority of the sites, the Ag, Pb, As, and Cd levels exceeded their baseline values, whereas the Ni and Co levels were equivalent to those of their baselines, at some sites. Soil samples at MMY were the most acidic while that of NMAV was the most alkaline. The pollution models indicated very high Ag contamination at OMV, NMV, and NMAV while all the sites showed very high contamination of Pb and Cd, and no Co, Ni, Hg, and Cr pollution was recorded for all the sites as shown by their Igeo values. The result for the enrichment factor showed anthropogenic sources of deposition of these heavy metals at all the sites. From the risk assessment models applied, none of the contaminated sites showed an estimated daily intake, hazard quotient, and total hazard index beyond the reference values, with Pb found to possess the greatest potentials of toxicity. This study has shown the necessity to periodically monitor and apply measures that can halt the environmental decay, occurring at the automobile workshops.