Discerning potable water sources using Monte Carlo based simulation for health risk assessment in Omu-Aran, Nigeria

Discerning potable water sources using Monte Carlo based simulation for health risk assessment in Omu-Aran, Nigeria

Human health is vulnerable upon exposure to persistent heavy metals (HMs) in environmental media such as groundwater even at trace levels. Therefore, this study aims to estimate the health risk posed by exposure to HMs using deterministic and probabilistic methods. Water samples were collected from 8 Hand dug wells (HWs) and 8 Boreholes (BHs) within Omu-Aran, Nigeria. The order of magnitude of the average contents for heavy metals are Zn > Fe > Al > Cu > Cr > Mn > Pb in HWs and Zn > Fe > Cu > Al > Cr > Pb > Mn for BHs. Pollution indices reveal that BHs were of better quality while HWs were more polluted. PCA shows contamination of HWs come from anthropogenic sources. Monte Carlo Simulation (MCS) technique was used to evaluate non-carcinogenic and carcinogenic risk in children and adults. The computed Hazard Index (HI) values for children and adults show the likelihood of exceeding the HI value of 1 is greater in children (90%) than in adults (16%) upon exposure to Cr in HWs. Computed lifetime carcinogenic risk (LTCR) values via oral pathways for Pb exposure are well below the 10−4, hence, no carcinogenic risk is expected upon exposure to Pb. Conversely, for HWs, LTCR values for Cr exposure in children ranged from 0 to 2.14*10−4, indicating that the current Cr levels pose a risk, especially for children. Hence, prolonged duration to HMs exposure via ingestion increases the possibility of having cancer. Sensitivity analysis reveal Exposure frequency and HMs concentration are the most significant input factors on the risk estimate. Overall, BHs represent a safe water source for both adults and children, while HWs could pose health risk in children due to elevated HMs levels.

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