Natural radioactivity and external hazard index in Brazilian sands

The distribution of natural radiation from Brazilian beach sands was studied using gamma-ray spectrometry. While in most of the regions studied the dose due to external exposure to gamma-rays, proceeding from natural terrestrial elements, are within the values 0.3 and 1.0 mSv/year, some sand samples from Bahia, Rio de Janeiro and Sao Paulo states present higher radioactivity levels due to the presence of monazite and zircon, exceeding the world average value for external exposure due to naturally occurring radionuclides.