Evaluation of Specific Activity Concentration of 238U, 232Th and 40K in Soil and Rice Grains from Solid Mineral Mining Sites in Ikwo Area of Ebonyi State, Nigeria

Evaluation of specific activity concentration of 238U, 232Th and 40K in soil and rice grains from solid mineral mining sites in Ikwo area of Ebonyi state was carried out using a Digilert-200 Radiation Meter. The radiological impact of the radionuclides was calculated. The average value concentrations of radionuclides obtained were 170.53, 9.26 and 8.81 (in Bq.Kg-1) for 40K, 238U and 232Th respectively in soil samples and 113.77, 5.86 and 7.08 (in Bq.Kg-1) for 40K, 238U and 232Th respectively in rice grain. These values are below the world permissive value of 400, 35 and 30(in Bq.Kg-1) respectively. All the health risk parameters calculated in soil and rice were below world permissive values. For the radionuclides in rice samples, the average annual committed effective doses(in mSvy-1) for ages (<1 year), (1 – 7 years), (7 – 12 years), (12 – 17 years) and (>17 years) are 0.37, 0.05, 0.04, 0.03, 0.02 respectively. These results are less than the world permissive value of 1.00 mSvy-1. Generally, the study shows that the rice consumption was relatively safe radiologically with little contamination which could be attributed to human activities but there is tendency for long term health hazards in future such as the cancer due to doses accumulation. It is recommended that the various human activities that raise the activity concentration in soil in Ikwo mining area that should be reduced. The activity concentration of radionuclides level in the area should be periodically assessed.