QUOTE : Radiation is all around us. It emanates from the sun and cosmic rays, bathing cities at high altitude in greater levels of background radiation than those at sea level. Underground deposits of thorium and uranium emit radiation, but so does masonry: stone, brick, and adobe all contain radioisotopes. The granite used to build the US Capitol is so radioactive that the building would fail federal safety codes regulating nuclear power plants. All living tissue is radioactive to some degree: human beings, like bananas, emit radiation because both contain small amounts of the radioisotope potassium 40; muscle contains more potassium 40 than other tissue, so men are generally more radioactive than women. Brazil nuts, with a thousand times the average concentration of radium of any organic product, are the world’s most radioactive food.