OCCURRENCE AND DOSE FROM INTAKE OF RADON IN DRINKING GROUNDWATER IN OGUN STATE, NIGERIA

Radon-222 concentrations in groundwater from 10 local government areas (LGAs) of Ogun State were measured using AlphaGUARD radon detector and AquaKIT. The mean activity concentration of radon ranged from 1.23 ± 0.21 to 12.68 ± 18.11 Bq.l-1 corresponding to geometric means (GMs) of 1.22- 6.39 Bq.l-1. The radon concentrations of all the samples were below the World Health Organization and European Commission guidance level of 100 Bq.l-1, with 17% higher than 11.1 Bq.l-1, recommended by the United States Environmental Protection Agency. Mean annual effective dose due to ingestion ranged from 0.020 ± 0.004 to 0.254 ± 0.353 mSv.y-1 (adults), 0.041 ± 0.007 to 0.509 ± 0.705 mSv.y-1 (children) and 0.024 ± 0.004 to 0.297 ± 0.411 mSv.y-1 (infants). That of inhalation varied from 0.303 ± 0.053 to 3.108 ± 4.440 μSv.y-1. The mean annual effective doses of some of the LGAs were higher than the International Commission for Radiological Protection recommended reference dose level of committed effective dose of 0.1 mSv from 1-year consumption of drinking water.