Brazil

• No unusual congenital abnormalities, stillbirths, or changes in live births could be found in a Brazilian study of 44,000 pregnancies, even though the background radiation was five to ten times "normal."
• (From the same investigation) "The high terrestrial radiation, 9 mGy/year [900 mrem/yr], in Espirito Santo, Brazil did not affect the fertility of 8,000 couples in this study. [Freire-Maya, A. and Kreiger, H. Human genetic studies in areas of high natural radiation. Health Physics, 34, 61, 1978.]
• The beaches of Guarapari have 25%-35% monazite sand giving a dose to vacationers (who bury themselves in it) of 0.03 mGy/hr (at least 30 mrem per ten-hour day - 420 mrem for a two-week vacation). Though it's illegal, the tourists steal the rocks and sand for their bedrooms at home. [Cullen, T.H., et al. Two decades of research in the Brazilian areas of high natural radioactivity. Radiation Protection: A Systematic Approach to Safety, Pergamon Press, Oxford, 1980.]