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The natural radioactivity due to the presence of 226Ra, 232Th and 40K in conventional raw materials and some solid industrial wastes and by-products which are being used or have a potential for use in the building and ceramic industries in Australia has been measured by gamma-ray spectrometry. The majority of materials examined in this work showed fairly low levels of radioactivity. Some samples of red mud, phosphogypsum, zircon products and fly ash did show higher levels of radioactivity than would be acceptable on the basis of a criterion formula for gamma-ray activity suggested for use in some OECD countries. But this higher level of radioactivity should not pose an environmental health problem when these materials constitute a relatively small portion of the materials used in a normal building. The present work has also shown that the radioactivity levels of some of the materials can be reduced through the removal of fines by sieving, as the fines seem to contain a higher concentration of radioactive nuclides.
Beretka et al. (Tue,) studied this question.