Natural Radioactivity Levels of 226 Ra and 228 Ra and Associated Radiological Risk in Borehole Water from...

Radiological investigation of 26 borehole water samples in Ogwashi-Uku, Nigeria has been carried out using γ -ray spectroscopy to assess the 226 Ra and 228 Ra levels and evaluate the health risks posed to indigenes of Ogwashi-Uku. Activity concentrations of 226 Ra range from 1.8 to 21.6 Bq L -1 with an average mean of 7.99 Bq L -1 and 1.9 to 11.3 Bq L -1 for 228 Ra with an average mean of 4.90 Bq L -1 , respectively. The calculated mean annual effective doses for the different age groups received by the local populace due to the ingestion of 226 Ra and 228 Ra were found to be above WHO permissible limit of 0.1 mSv y -1 for 228 Ra and 226 Ra. The mean value of excess lifetime cancer risks were found to be higher than WHO permissible limits of 10 -3 . This implies a risk of developing cancer immediately over a lifetime due to the consumption of the sampled borehole water. The results in this study may form part of a larger baseline values of the database in Delta State, Nigeria, and the world that will help in setting up radiological safety guidelines with respect to consumption of borehole water.