Abstract:
Radiations of both natural and artificial origin are readily available in the environment. Building materials like stones, cement, ceramics, water and sand contain radioactive nuclides, which are harmful to mankind. Elevated levels of radiation from these materials are potential causes of prompt or delayed harmful effects to human health. The ceramic tiles which were the focus of this study are made from mixture of earthly matter including kaolin, quarts, talc and feldspar which contain primordial radioisotopes like Thorium-232(232Th), Potassium-40(40K) and Uranium-238(238U) known to release radiations. This study was aimed at establishing the levels of radiations from ceramic building tiles used in Kenya. A total of 37 samples of tiles from different countries and manufacturers were analyzed. Thallium doped sodium iodide gamma-ray counter (NaI (TI)) was used for data acquisition. A mean activity concentration of 53.73±2.34BqKg-1 for 232Th, 43.17±3.40BqKg-1 for 238U and 525.99±36.10BqKg-1 for 40K was obtained. The comparison of the obtained activity concentration values with other related studies indicated that the activity of the radio nuclides is dependent on the geological composition of the raw material source. Using the activity concentration values obtained, the dose rates and the hazard indices thereof were calculated. Mean values for radium equivalent activity, absorbed dose, indoor and outdoor annual effective dose, and hazard indices (internal and external) obtained were 159.59BqKg-1, 75.55nGyh-1, 0.28, 0.19, 0.54 and 0.43 respectively. The highest recorded value of hazard index (both internal and external) was found to be 0.92 while the lowest was 0.15 which are both below the world’s safety limit of a unit recommended in the International Commission for Radiation Protection (ICRP) reports. Generally, the ceramic building tiles in the Kenyan market as at the time of this study were safe for human handling as seen from the radiological parameters.
