Comparative assessment of natural radioactivity and radiological hazards in building tiles and sharp sand sourced locally and those imported from China and India

Thirteen (13) types of building tiles and Sharp sand commonly used for building purposes were collected for their radionuclide contents analysis. Both imported and locally produced building tiles were examined.   The samples of tiles and sand were crushed to powder and they were prepared such that their content could be examined by the use of gamma-ray spectrometry. The average activity concentration of 238U (60.61 Bq/kg), 232Th (76.55 Bq/kg) and 40K (528.40 Bq/kg) for all the samples were observed to be higher than the world recommended standard of 35, 30 and 400 Bq/kg respectively. The external and internal hazard indexes were estimated for all the building materials, the average results were found to be below the recommended limits. However, samples 3 and 6 reported internal hazard indices of 1.08 and 1.06 respectively, which are higher than the world standard. Furthermore, the estimated absorbed dose rates were observed to be within the recommended safe limits. Moreover, a comparative study of the products revealed that the results of the measured parameters from both India and China products are far higher than Nigeria products by a factor of about 1.34. The results obtained showed the following trend of activity concentration for the analyzed samples, India > China > Nigeria, which implies that a long exposure to both India and China products poses higher risk to the inhabitants.