Radiological indices estimation from radon concentration in selected groundwater supplies in Abeokuta, south western Nigeria

Abstract

Lung cancer has been linked to long-term exposures to radon through food or water consumption, inhalation in caves or closed chambers, or exposure to radon-saturated open air. In Abeokuta, Nigeria, 58 samples of drinking water were tested for radon. 25 samples from a hand-dug well and 33 samples from a borehole of water used for drinking and other domestic purposes were each taken from different locations in Abeokuta. For this study, the RAD7 Radon Monitor system was employed. The water samples were taken using a 250 mL radon-tight bottle. A bubbling kit was included with the radon detector. Radon measurements were performed using the WAT 250 technique and grab mode on the water samples. On each sample, a total of two cycles were performed. The findings revealed that the mean value for radon concentration in borehole drinking water samples is 18.8 Bq/L, with a range of 10.65-29.5 Bq/L. In contrast, the measured samples from hand-dug wells range from 1.41 to 20.02 Bq/L, with a mean value of 9.7 Bq/L. 100% of borehole water samples and 48% of hand-dug well water samples showed radon concentrations over 11 Bq/L, the maximum contamination limit advised by the US Environmental Protection Agency (EPA). Furthermore, water samples from boreholes range between 0.037 and 0.081 mSv per year with an average mean of 0.051 mSv per year, while the total annual effective dose of radon concentration due to ingestion and inhalation from hand-dug well samples ranges between 0.0038 and 0.055 mSv per year with a mean of 0.027 mSv per year. No samples from hand-dug wells or boreholes have cumulative yearly effective doses of radon that are higher than the maximum contaminant level advised, which is 0.1 mSv/y.

Keywords: Abeokuta; Annual effective dose; Groundwater; Inhalation and ingestion; RAD 7 solid state detector; Radon concentration.