Heavy metal(loid)s contamination and ecotoxicological hazards in coal, dust, and soil adjacent to coal mining operations, Northwest Pakistan

Heavy metal(loid)s (HM) are ascertained hazardous to the environment due to their toxic, bioaccumulative, and persistent nature. Coal, dust, and surrounding soil near coal mines (n = 21) in each specimen were examined for HM in the districts of Hangu and Kurram. Samples were investigated for HM using the atomic absorption spectrophotometer. Iron (Fe) exhibited the highest mean concentrations, whilst molybdenum (Mo) showed the lowest in the selected coal, dust, and soil specimens were 62,100 and 1.14, 52,610 and 0.9, and 45,300 and 2.0 mg/kg, respectively. HM in studied media was evaluated for ecotoxicological factors, namely contamination factor (CF), potential-ecological risk index (PERI), hazard index (HI), and cancer risk. CF values of dust were very-high and considerable due cadmium (Cd) in the districts of Hangu and Kurram, while that of soil were considerable in both districts. The ecological-risks (190 < PERI<380) were "considerable" due to dust and soil of the Hangu district, while the "moderate" ecological-risk (95 < PERI<190) was noted for the Kurram district. The HI values surpassed the limit of 1 for children due to soil and dust exposures. Higher HI values may pose chronic health risks to the locals. Among exposure routes, oral ingestion was noted as the primary pathway's. CR values were noted as less than the threshold set by the US EPA. This study recommended that HM contaminations be monitored periodically on a priority basis to develop strategies for combating the problem of health concerns.