Since the beginning of time, all living creatures have been, and are still being, exposed to radiation. Nonetheless, most people are not aware of all the natural and man-made sources of radiation in our environment. Natural sources of radiation account for about 50 percent of human exposure, while man-made sources account for the remaining 50 percent. This article discusses various sources of radiation we find both man made and natural.
A worker holding a plutonium button. Plutonium, a man-made substance, was rare. Scraps resulting from production and plutonium recovered from retired nuclear weapons were reprocessed into valuable pure-plutonium metal.