Radiological Risk Assessment of Building Materials Used in Federal College of Education (Technical) Akoka, Lagos State, Nigeria

Abstract

Multiple building constructions necessitating a regular influx of different soils for building purposes within Federal College of Education (Technical) Akoka, in Lagos State, Nigeria spurred a radiological risk assessment of selected soil samples. Five (5) construction points were identified and ten (10) soil samples were collected. A gamma spectrometer was used to evaluate the natural radionuclides (226Ra, 232Th, and 40K) present in the soils. IAEA-certified standard materials of RGU-1, RGTh-1, and RGK-1 were used to determine the full peak efficiencies of gamma energies 609, 1120, and 1764 keV for 238U, 2614 keV for 232Th and 1460 keV for 40K. Activity concentration, absorbed dose, annual effective dose equivalent, hazard indices, and excess lifetime cancer risk (ELCR) were estimated to assess possible radiological risks in the building soil samples. Results from the analysis revealed the highest radioactivity among soil samples was 674.3 Bq/kg from 40K and the lowest was 18.5 Bq/kg from 226Ra. The absorbed dose (D) varies from 65.8 nGy/h to 215.3 nGy/h with an average value of 136.6 nGy/h, and the annual effective dose equivalent ranged from 0.081 mSv/y to 0.264 mSv/y with an average value 0.168 mSv/y. The internal and external hazard index ranged from 0.49 −1.46 and 0.39 − 1.32 respectively which is not completely below the hazard index threshold value ≤1 as recommended by UNSCEAR. The ELCR values ranging from 0.222 × 10-3 − 0.726 × 10- 3 with an average value of 0.461 × 10-3 predicted an insignificant carcinogenic risk with the probability of four persons in every 10,000 persons.

Keywords

• absorbed dose
• annual effective dose equivalent
• elcr
• external hazard index (hex)
• gamma spectrometer
• internal hazard index (hin)