Mapping and assessment of activity concentration of 222Rn and its associated exposures from the drinking water sources of Taraba State, Nigeria

This study assessed the activities of 222Rn and their likely exposure rates from the drinking water sources of Taraba State and represent the 222Rn concentrations on map of Taraba, which is very important to environmental and health officers of the state and the general public. A Liquid Scintillation Counter (LSC) set-up at the Centre for Energy Research and Training (CERT), Ahmadu Bello University, Zaria, Nigeria, was used to determine the activity concentrations of 222Rn in water samples. The activity of 222Rn in the water samples of the state ranged from below the detection limit (BDL) to $$11.5 Bq/L$$ , with an average value of 5.7 ± 0.3 Bq/L . This mean value though it is below the $$10 Bq/L$$ of WHO and $$11.1 Bq/L$$ of USEPA recommendations but is higher than $$0.1 Bq/L$$ acceptable limit for Nigerian Standard for Quality Drinking Water (NSQDW). The iso-concentration map of the state showed that Takum, Ussa, Bali, Sardauna, Gashaka, Yorro, Zing, Lau, Karim Lamido, and Jalingo local government areas (L.G.As) of the state had 222Rn concentrations above $$5.5 Bq/L$$ , while Ardo-Kola, Ibi, Wukari, and Donga L.G.As had 222Rn concentrations below $$5.5 Bq/L$$ . The total yearly effective dosage (YED) resulting from ingesting and inhaling radon-contaminated water in Taraba state were found in the range of BDL to 112.6 μ Sv/y with a mean value of 55.7 ± 2.8 μ Sv/y . It was observed that there is a direct proportional relationship between the total YED and activity concentration of 222Rn in the state. Hence, an increase in the activity concentration of 222Rn in the state relates to 9.82 μ Sv/y increase in total YED in the state.