Monte Carlo approach to risks assessment of heavy metals at automobile spare part and recycling market in Ilorin, Nigeria

This study evaluates the sources and health risks associated with heavy metals in Ipata spare part market in Ilorin, Nigeria. Soil and water samples were collected within and outside the market for heavy metal (As, Pb, Mg, Mn, Cd, Cr, Cu, Zn, Fe and Ag) analysis using Atomic Absorption Spectrometry. The results indicate that all the heavy metals analyzed show higher concentration within the recycling market than the control location. The concentration of heavy metals at the market decreases with an increasing depth between 0 and 50 cm and appears to be stable below 50 cm of the soil depth. All the Hazard Indices (HI) estimated for the soil samples are less than one (< 1) which is the standard set by USEPA, whereas, the Hazard Index (HI) for the water samples within the station is greater than 1. The Incremental Lifetime Cancer Risk (ILCR) for soil samples ranged from level I to level V, while that of water samples ranged from level VI to Level VII based on Delphii method of classification. This shows that the main lifetime cancer risk occurs through the water exposure pathway. Similarly, according to the mean, P5% and P95% cumulative probability using the Monte Carlo simulation, the ILCR is above the acceptable range of 1.00E−6 and 1.00E−4. All the pollution indices reveal that the significant pollution at the park is more of anthropogenic than pedogenic and lithogenic. Therefore, the market is contributing immensely to environmental pollution which may lead to unforeseen danger to human health.