Radon contamination, risk evaluation, and their spatial distribution in groundwater of three selected northern districts

Radon (²²²Rn) has a ubiquitous nature in the environment and can pose serious health threats to living beings. Groundwater is the primary source of drinking and domestic uses for >3 million people in the area. The current study was conducted for investigation of groundwater for the ²²²Rn concentration and associated health risks. For that purpose, the groundwater was examined for ²²²Rn concentration using the RAD7 detector (Durridge Company, USA). Average concentrations of ²²²Rn were highest at 10.8 ± 3.6 Bq/L in the Lower Dir district and lowest at 6.39 ± 0.98 Bq/L in the Upper Dir. The average concentration of ²²²Rn was found below the threshold limit set by the US Environmental Protection Agency (USEPA) and the World Health Organization (WHO). However, the concentration in 30 % of sampling sites in the Lower Dir showed ²²²Rn concentrations higher than a recommended level of 11.1 Bq/L. This study evaluated the potential non-cancer risk and estimated lifetime cancer risk (ELCR) of various age groups via ²²²Rn consumption in groundwater. The results showed´s total annual mean exposure doses (EwTotal) values for infant of 43.7 ± 10.2, 25.2 ± 3.15, 27.0 ± 1.68 μSv/a, children 33.5 ± 7.80, 19.3 ± 2.42, 20.1 ± 1.29 μSv/a), and adults (32.3 ± 7.52, 18.6 ± 2.33, 20.0 ± 1.24 μSv/a) via groundwater intake in Lower Dir, Upper Dir, and Chitral districts, respectively. Infants showed higher vulnerability to health issues due to ²²²Rn contamination in groundwater. ²²²Rn concentrations showed a weak correlation with various studied physicochemical parameters in the groundwater.