Artificial radioactivity produced high risks of large-scale environmental contamination during World War II after nuclear bombardment at Hiroshima and Nagasaki in August 1945 .
These two radionuclides have very long half-lives and considered main contributors to the whole collective dose from artificial radioactivity.
Some examples of these are: the discovery of the radioactivity of thorium, and the new elements polonium and radium (1898); the identification of alpha and beta radiation (1899); the Rutherford/Soddy disintegration theory (1902); the discovery of isotopes (1909); the Rutherford nuclear theory of the atom (1911); the Bohr theory of the atom (1913); the disintegration of nitrogen atoms (1919); the discovery of artificial radioactivity
(1933); and the discovery of nuclear fission (1938).
This is called artificial radioactivity
, since it comes about as the result of bombardment of nuclei in the laboratory.
Scientists induced artificial radioactivity
for the first time, extended the periodic table, tapped the sun's energy with two experimental solar motors, and predicted that man would soon harness atomic energy.