ASSESSMENT OF RADIOACTIVITY AND RADIOLOGICAL HAZARDS ASSOCIATED WITH CLAY BRICKS IN JALINGO CITY AND ITS METROPOLIS, NORTH-EASTERN NIGERIA

Abstract

This study estimates the radiation safety of soils used in making clay bricks, a common building material in Jalingo City and its surrounding areas. The activity concentration of the natural radioactive elements ²³⁸U, ²³²Th, and ⁴⁰K in the soils was measured using a gamma-ray spectrometer equipped with a 905-3 NaI (TI) crystal detector and a high photomultiplier measuring 7.62 cm by 7.62 cm. The average activity concentrations of ²³⁸U, ²³²Th, and ⁴⁰K in the soils were 12.5±1.3, 26.7±1.7, and 65.1±5.2 Bqkg^-1 respectively, all of which were lower than the global average concentrations. The research also assessed the Radium equivalent activity, absorbed dose rates, and other radiological hazard parameters relevant to building materials. The mean Radium equivalent activity was 55.69 Bqkg^-1, below the safety limit of 370 Bqkg^-1. Additionally, the mean outdoor absorbed dose rate was 24.64 nGyh^-1, below the safety limit of 59.00 nGyh^-1, and the mean indoor absorbed dose rate was 46.08 nGyh^-1, below the safety limit of 84.00 nGyh^-1. All assessed hazard parameters, including annual effective dose rates (indoor and outdoor), lifetime cancer risk, annual gonadal effective dose, representative level index, and both external and internal hazard indices, were well below the established global safety limits. The activity concentration of the primordial radionuclides and the radiological hazard parameters were also lower compared to other parts of Nigeria and the world. As a result, the study concluded that the soils and the buildings constructed with them are radiologically safe and pose no hazard threats to the occupants.