Assessment of Natural Radioactivity Hazard in Water Sample in some parts of Delta State, Nigeria

Abstract

In this study, the radioactive activity concentrations (AC) are determined, along with radiological parameters such as absorbed dose rate, internal hazard index, radium equivalent activity index, excess lifetime cancer risk, and committed effective dose (mSvy-1). This resulted in relatively high activity concentrations in all water sources in the study area, with average activity concentrations exceeding WHO recommended levels of permissible drinking water of 10, 1.0, and 0.1 Bql-1 for 40K, 238U, and 232Th and 1.0, and 0.1 Bql-1 for Radium Equivalent Activity Index (226Ra, 228Ra), respectively (WHO,2008). The descriptive statistical overview of the AC for each location is for 40K, 238U, 232Th and Raeq, radionuclides in the water samples ranged from 129.89 ±11.37 to 345.78 ±7.99 Bql-1, 5.29 ± 0.11 to 10.24 ± 2.05 Bql-1, 1.58 ± 0.03 to 9.06 ±2.12 Bql-1 and 22.33- 40.14 Bql-1 respectively. These results demonstrate that samples UKW 5 (Ukwuani LGA), INE 3 (Ika North East LGA), OSN 3 (Oshimili North LGA) and ANS 5 (Aniocha South) have the highest values for 40K, 238U, 232Th and Raeq, respectively, while samples PAT 1 (Patani LGA), INE 5 (Ika North East LGA), UKW 4 (Ukwuani) and ISS 1(Isoko South LGA) have the lowest for 40K, 238U,232Th and Raeq respectively. Test of significance by one-way analysis of variance (ANOVA) shows no significant differences (p ≥ 0.05) exist between the LGA and there exist a significant value with the WHO value. The results also shows the statistics of the radiological parameter which ranges from 0.008 - 0.033 where OSS 2, UKW 4, PAT 3,ISN 2 has the lowers value of 0.008 while OSN 2 has the highest value of 0.033 with a mean of 0.014±0.001. The excess lifetime cancer risk and statistics for every local government area in the study region were above the world average value of 10-4 (EPA, 2012). This implies that the chances of having cancer in the study area is significant. Therefore all the sources of drinking water in this area of study must be treated before consumption to avert the likely health implications.