Assessment of radiation dose level and excess lifetime cancer risk associated with dust samples collected from selected nursery and primary schools in Ife Central and Ife East, Osun State, Nigeria.

Primordial radionuclides are, among others, sources of radiation exposure to man. In this study, dust from some 24 nursery and primary schools in Ife Central and Ife East Local Government Areas (LGA) of Osun State were collected and analysed for 238U, 232Th, and 40K using CsI scintillation detector connected to a Universal Radiation Spectrum Analyser (URSA II) for spectrum analysis. From the specific activity concentrations of 238U, 232Th, and 40K, absorbed dose rates and radiological parameters were calculated. The mean activity concentrations of 238U, 232Th, and 40K in Bq/kg were found to be (45±2, 46±2), (56±5,60±5) and (669±76, 744±86) respectively for Ife Central and Ife East LGAs, however, the difference between the data sets from the two communities were not statistically significant. The total mean ± S.D (standard deviation) calculated over the whole study area were as follows; 238U= 45±11; 232Th=58±15 and 40K=702±196. The values of these radionuclides’ activities were higher than the world averages of 33, 45, and 420 for 238U, 232Th, and 40K respectively set by UNSCEAR. The mean absorbed dose rate in the air (in nGy/h) for Ife Central was 85±7 while for Ife East was 92±8. Both values were higher than the world average of 55 nGy/h. Also, the excess lifetime cancer risk was 1.66 × 10-3 for Ife Central and 1.8 × 10-3 for Ife East LGAs. Generally, Ife East LGA has higher activity concentrations than Ife Central LGA although the difference is not statistically significant.