Measurement of natural radioactivity in Brazilian beach sands

The distribution of natural radionuclide γγ-ray activities and their respective annual effective dose rates, produced by 40K, 226Ra and 232Th, were determined for sand samples collected along the coast of four Brazilian States: São Paulo (SP), Rio de Janeiro (RJ), Espírito Santo (ES) and Bahia (BA). For some specific beaches, the values of the annual effective dose rates or γγ-ray radiation hazard indices exceed the average worldwide exposure of 2.4mSvy-1 due to natural sources and the limits proposed by Organization for Economic Co-operation and Development for building materials. The average values of the radium equivalent activities were evaluated and found to be 696Bqkg-1 in Mambucaba (RJ), 1621Bqkg-1 in Buena (RJ), 2289Bqkg-1 in Anchieta (ES), 10205Bqkg-1 in Meaipe (ES), 83425Bqkg-1 in Guarapari (ES), 531Bqkg-1 in Vitória (ES), 2026Bqkg-1 in Serra (ES), 3240Bqkg-1 in São Mateus (ES), 3075Bqkg-1 in Porto Seguro (BA) and 1841Bqkg-1 in Itacaré (BA). These values are above the limit of 370Bqkg-1 recommended for the safe use of building materials for dwellings by OECD.