Abstract
The ceramic industry encompasses a varied group of producers and products. One of the main subsectors is the production of ceramic tiles. The consumption of ceramic tiles has experienced a considerable increment during the last decades, associated mainly to the development of the building sector. Ceramic tiles are considered building material as they are used as cover liner of floors and walls. Measurements of ceramic tiles and raw materials used in them, show that natural radionuclides of uranium (238U) and thorium (232Th) series, together with the radioactive isotope of potassium (40K) are present. Uranium series contain radium, which decays to radon (222Rn), an inert gas that can be released from materials and inhaled by individuals. Limits of 226Ra concentrations are established by different countries in order to control Radon levels (200 Bq/m3 in European Union) for internal dose calculation. 40K, 226Ra and 232Th descendants can cause an external dose. Therefore, with the purpose that individual doses due to building materials do not exceed a certain level, recommendations or regulations have been established. In practice an easy way to avoid building materials provide doses to individuals over the reference level is to introduce an index depending on activities concentrations of 226Ra, 232Th and 40K, defined so that the dose limits will never be exceeded. These limits and indexes present differences between countries. In this paper indexes are compared and differences are discussed. From the results exposed in this work, it is evident that certain ceramic tiles can or cannot be used as building materials depending on the index applied. Consequently, manufacturers of ceramic tiles to be exported should keep in mind these indexes as well as the concentrations of radioactive pollutants of their products to avoid problems in the customers.
