The study of the fate and effects of radioactive materials in the environment. As a hybrid field of scientific endeavor, it is founded upon, and derives its basic principles from, both of its parent disciplines, that is, basic ecology and radiation biology. Following the discovery of ionizing radiation and radioactive particles in biological studies in the 1940s and 1950s, these phenomena were studied under what were usually controlled laboratory conditions. Soon after, however, a need was demonstrated for a better understanding of the fate and effects of radioactive materials that were being released into the environment following the use or testing of nuclear weapons. This need became an important factor in the emergence of radioecology as a scientific discipline in its own right.