Estimation of Annual Effective Dose Due to Ingestion and Inhalation of Radon in Groundwater from Kaduna, Nigeria

The variation in the concentration of radon in groundwater sources comprising of boreholes and wells in Kaduna metropolis and environs were determined by using Tri-carb LSA 1000 liquid scintillation counter. The radiation dose received by individuals within different age groups categorized under; infants, children and adults, depending on their average annual water consumption rates (ACRs) were also estimated. The mean radon activity in 16 boreholes and 18 well water samples were 1.8/Bq/L and 0.57 Bq/L respectively; while the average radon activities ranged from 0.85 to 2.57 Bq/L and 0.35 to 0.85Bq/L respectively with all values far below the United States Environmental Protection Agency MCL of 11.1 Bq/L. All the estimated annual committed effective dose (ACED) for all samples were observed to increase with radon concentration, age and ACRs, but were significantly lower than the United Nation Scientific Committee on Effect of Atomic Radiation (UNSCEAR) and World Health Organization (WHO) recommended limit of 1mSv/yr. The radiation dose rate received by the lung cells due to the inhalation of waterborne radon in the air was considerably higher when compared to that received by the stomach walls via ingestion.