Measurements of radioactivity levels in part of Ota Southwestern Nigeria: Implications for radiological hazards indices and excess lifetime cancer-risks
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Super SPEC RS-125 radiation detector with large 2.0 x 2.0 NaI crystal and linear
energy ranging from 0.80 MeV to 1.2 MeV was used to measure the activities of primordial
nuclides and the radiation dose exposures rate in Iyana-Iyesi, Ota, southwestern Nigeria. The
measured activities vary from 17±0.02 Bqkg-1 to 30.49 ±0.01 Bqkg-1, 50.01 ±0.16 Bqkg-1 to
158.49±0.17 Bqkg-1, and 406.9±0.42 Bqkg-1 to 1275.48±0.82 Bqkg-1 for 238U, 232Th and 40K
respectively. The acquired gamma radiation dose rate range from 138.696 ±2.06 (nGyh-1) to
350.103±7.21 (nGyh-1) with mean value of 148.22 (nGyh-1), almost three times higher than the
recommended safe limit of 55 (nGyh-1). The measured activities and radiation dose rate were
engaged to estimate the annual outdoor effective dose, gamma index, excess lifetime cancer
risks and annual gonadal dose equivalent. It was observed from all the estimated parameters,
those values in the study area are well above the recommended safe limit for normal
background radiation. This suggest that the dwellers and those using the excavated
geomaterials from this area for construction purposes are exposed to very high radiation from
natural radionuclides. Further research to evaluate the mineralogy and geochemistry of the clay
deposits in the area is highly recommended
Keywords
Q Science (General), QC Physics