Radon concentration in water sources and its associated cancer risks to the populace of Ede, South Western Nigeria

Abstract

An estimated two billion people do not have access to portable and clean drinking water due to diverse pollutants present in water, including Radon (²²²Rn). For this reason, the World Health Organisation (WHO) designated clean water and sanitation as goal $♯$6 in its 2030 sustainable development (SDG) agenda. This work aimed to measure the concentrations of radon in various water sources at Redeemer’s University campus, Ede, and its environment, and to estimate the associated radiological health hazard. Thirty five (35) boreholes, surface water and hand-dug well water were sampled and analysed for (²²²Rn) content, and its health risk estimated using the annual effective dose (AED) and the excess lifetime cancer risk (ELCR). (²²²Rn) distributions in borehole water samples, ranged from 0.51 ± 0.40 to 36.25 ± 2.80 Bq$l^{-1}$. For the hand-dug well, it ranged from 1.75 ± 1.00 to 5.91 ± 0.20 Bq$l^{-1}$, and for the stream water, it was 0.106 ± 0.1 Bql⁻¹. The mean radon concentration in surface water, borehole water, and hand-dug well sources were 0.106 ± 0.1 Bq$l^{-1}$, 15.35 ± 9.73 Bq$l^{-1}$ and 4.25 ± 1.72 Bq$l^{-1}$, respectively. The measured values in all the water samples was distributed between 0.106 Bq$l^{-1}$ and 36.250 Bq$l^{-1}$, the average value was 13.330 Bq$l^{-1}$. The mean AED from inhalation and ingestion of (²²²Rn) gas was 39.259 $\mu$Svy⁻¹. Total AED received from all water sources was estimated to be less than 100 $\mu$Svy⁻¹, which is the WHO and European Union (EU) Commission recommended value. The estimated ELCR showed probabilities of 1 ± 1, 30 ± 12 and 108 ± 70 cases per a million people developing cancer from exposure to radon from surface water, hand-dug wells, and borehole water sources, respectively, which were within the United States Environmental Protection Agency (USEPA) reference limit. This implies that, at present the entire community is safe from any radiologically linked health effects that could arise from exposure to radon gas from water sources.