Groundwater pollution by trace metals and human health risk assessment in central west part of Bangladesh

To evaluate the trace element contamination level and human health risk in study area, a total of twenty groundwater samples were collected and analyzed for pH, EC, Cu, Cd, Fe, Mn, Ni, and Zn. The results revealed that, groundwater is slightly acidic in nature with the mean conductance of 686.10 mu s/cm. Heavy metal evaluation index (HEI), the degree of contamination (Cd) and nemerow pollution index ( NI) were employed to estimate the pollution load, and it was found 5%, 95%, and 75% of samples exhibits the high degree of pollution respectively. According to the spatial analysis it was found that, south-central part of the study area is highly contaminated with trace elements. Moreover, Pearson correlation, principal component analysis (PCA) and cluster analysis (CA) were applied to identify the pollution source and factors controlling groundwater quality, and the results indicates that groundwater of the study area were influenced by both natural and anthropogenic factors. Chronic health risk via exposure of both oral and dermal routes were also determined by calculating the hazard quotient (HQ) and hazard index (HI), for both adults and children. In case of oral exposure, almost 85% of samples suggest the medium category of chronic risk for adult, and 50% of samples were found at high risk for children. Again, dermal exposure showed comparatively lower risk than oral exposure, and 55% and 80% of samples attributed medium chronic risk for adult and children respectively. However, the carcinogenic risk of cadmium (Cd) via oral exposure pathway suggest, all of the samples are at high risk for both adults and children. Average lifetime cancer risks (LTCR) of Cd for both adult and children were found to be 4.55E-4 and 5.59E-4 respectively, that indicated high carcinogenic risk. Results of sensitivity analysis specified concentration has high impact on carcinogenic risk both for adult and children.