Radioactivity in raw materials and end products in the Italian ceramics industry

The natural radioactivity due to the presence of 238U, 232Th and 40K in zirconium minerals (zircon and baddeleyite) used in the Italian ceramics industry, in tiles and in waste sludges resulting from ceramic processes, has been measured. The measurements were made by γ-ray spectrometry with a high-purity germanium (HPGe) detector connected to a multichannel analyser. The average concentrations of 238U and 232Th observed in the mineral samples (>3000 and >500 Bq kg−1, respectively) are higher than the concentrations found in the earthʹs crust by one or two orders of magnitude. The specific activities of tiles and sludges are much lower than in zirconium minerals. The 238U and 232Th concentrations in tiles (50–79 and 52–66 Bq kg−1, respectively) are not higher than in other building materials. The 238U concentration of sludges (116–193 Bq kg−1) is 4–6 times higher than the mean value for the earthʹs crust. The results are examined on the basis of the existing Italian legislation (D.Lgs no. 230, 1995, Gazzetta Ufficiale 13/06/1996, no. 136, Supplemento Ordinario, Rome, Italy) and the EC Directive no. 29/Euratom of the year 1996 (Gazzetta Ufficiale della Communità Europea 29/06/1996, no. L159).