Background radiation level measurement using hand held dosimeter and gamma spectrometry in Ijebu-Ife, Ogun State Nigeria

Background: The knowledge of distribution of radionuclides and background radiation levels in the environment is important for assessing the effects of radiation exposure due to both terrestrial and extra-terrestrial sources. Materials and Method: In-situ gamma dose survey and gamma spectrometry was employed to investigate background radiation levels in Ijebu-Ife. Results: In-situ gamma dose rates vary from 0.02 to 0.10 μSv/hr with mean value of 0.05 μSv/hr which is less than 0.133 μSv/hr, recommended by the ICRP. The resulting annual effective dose was below 1 mSv/yr maximum permissible limit for the general public set by the UNSCEAR, 2000. The activity concentrations of the three naturally occurring radionuclides in soils ranged from Below Detection Level (BDL) to 320.11 ± 28.53, 9.11 ± 1.65 and 8.55 ± 0.95 Bq/kg with mean values of 119.05 ± 11.24 Bq/kg, 4.44 ± 1.01 Bq/kg and 4.55 ± 0.62 Bq/kg respectively which are lower than the average values of 400, 35, and 30 Bq/kg recommended by the UNSCEAR, 2000 for 40K, 226Ra, and 232Th respectively. The mean computed values for absorbed dose rate, annual effective dose and radium equivalent are 10.03 nGy/hr, 0.03 mSv/yr, 20.11 Bq/kg respectively, which fall within UNSCEAR, 2000 threshold. Conclusion: A significant positive relationship exists between the in-situ and evaluated effective dose equivalents (r = 0.89, p < 0.05). Radiation dose results indicate insignificant radiological risk, making the study area safe for living and agriculture purposes.