Evaluation of the Radiation Hazard Indices and Excess Life Time Cancer Risk Due to Natural Radioactivity in Ground Water in Mining Areas of Plateau State

Abstract

The radiological implications of water intake from ground water supply in mining areas of Plateau State have been estimated. Fifty eight ground water samples (23 boreholes and 35 well samples) were randomly taken in two litres plastic containers within the Naraguta Topo sheet 168 covering the mining areas. About 10ml of Nitric acid was added to each sample at the point of collection for preservation. The samples were later evaporated and transferred into planchets. They were then counted for gross alpha and beta activity concentrations using MPC-2000-DP. The results obtained showed that the range of alpha activity concentration varied from (0.110 – 1.550)Bq/l for borehole sample and (0.010 – 12.590)Bq/l for well samples. The range of beta activities concentration varied from (0.012 – 2.760)Bq/l for borehole samples and (0.020 – 14.640)Bq/l for well samples. The hazard indices and excess lifetime cancer Risk were evaluated. For borehole samples the mean value for AEDE, AGED and ELCR for alpha emitting radionuclides were 0.157mSv/yr 0.039 mSvr/yr and 0.548 x 10-3 respectively while beta emitting radionuclides had the mean values of 0.134mSv/yr, 0.668mSv/yr and 0.468 x 10-3 respectively. For well water samples, the mean values of AEDE, AGED and ELCR for alpha emitting radionuclides were 0.335mSv/yr, 0.084mSv/yr and 1.172 x 10-3 respectively while beta emitting radionuclides had mean values of 0.393mSv/yr, 1.964mSv/yr and 1.375 x 10-3 respectively. Almost all the values are above their acceptable standards. It can be concluded that there is a significant radiological hazards to the people in the study area which can be attributed to the mining activities that took place in the area