They did not exist on earth until created by scientists. All radiation causes cancer. Most of the space occupied by an atom is empty. Electromagnetic radiation should be avoided at all costs. The human body is capable of detecting radioactivity.
Nuclear wastes are initially high in temperature and radioactive.
All atoms of a given element are alike in all respects. Small amounts of matter are converted into immense quantities of energy in nuclear bombs. The human body naturally contains a small amount of radioactive material. The majority of nuclear waste generated to date has come from nuclear power plants. Cells that divide rapidly are more sensitive to radiation than are cells that divide slowly.