Natural radionuclides are found in soil and are capable of disintegrating leading to the release of ionizing radiations that can have harmful effects on individuals exposed to them most especially when exceeded the recommended limits. Assessment of activity concentrations of 40K, 238U and 232Th, in surface soils samples from some public primary and secondary schools in Sagamu, Ogun State in Nigeria had been determined by gamma spectrometry using NaI (TI) detector coupled with a pre-amplifier base connected to a multiple channel analyzer (MCA) which was used to calculate the radiological indicators. 10 samples were collected from areas that were densely populated based on classrooms, playing ground, assembly ground, staffroom and administrative office. The mean activity concentrations of 40K, 238U and 232Th obtained from the soil samples were 388.61 ± 4.58 Bqkg-1, 25.05 ± 3.87Bqkg-1 and 39.63 ± 3.59Bqkg-1 respectively. The mean external hazard index (Hex) and mean internal hazard index (Hin) for all the soil samples were calculated to be 0.3015 and 0.3692 respectively, while the mean radium equivalent activity was obtained to be 111.56 Bqkg-1. The mean absorbed dose rate value was calculated to be 53.49nGyhr-1 with mean annual effective dose equivalent of 0.0656mSvy-1 and the mean excess lifetime cancer risk for outdoor exposure of 0.2297 x 10-3. The values of the radiological parameters: mean external hazard index and mean internal hazard index, mean radium equivalent activity, mean absorbed dose rate, and mean excess lifetime cancer risk are within the limits of 1.0, 370Bqkg-1, 55.00nGy/hr, 1.0mSvyr-1 and 1.45 x 10-3 recommended by European Commission, OECD, UNSCEAR, UNSCEAR and ICRP respectively and therefore have no negative radiological health implication to the people in the study area.
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