Lerner, K. Lee. Radiation exposure in Lerner B.W., Lerner K. Lee, eds. Worldmark Global Health and Medicine Issues (WMGH). Cengage, 2015
Radiation exposure occurs any time that electromagnetic rays or fast-moving particles interacts with living tissue. Ionizing radiation is particularly damaging to tissue; examples include x rays, gamma radiation, and fast-moving subatomic particles such as neutrons. Biological damage caused by exposure to ionizing ranges from mild tissue burns to cancer, genetic damage, and ultimately, death.
While radiation in the form of heat, visible light, and even ultraviolet light is essential to life, the word "radiation" is often used to refer only to those emissions which can damage or kill living things. Such harm is specifically attributed to radioactive particles as well as the electromagnetic rays with frequencies higher than visible light (ultraviolet, x-rays, gamma rays). Harmful electromagnetic radiation is also known as ionizing radiation because it strips atoms of one or more of their electrons, leaving highly reactive ions called free radicals which can damage tissue or genetic material.
There are, however, potential benefits of controlled exposures to certain kinds of radiation, which can be used for the detection, diagnosis, and treatment of certain diseases. (download to read more)