World War Two ended. Enrico Fermi had been the first to use a neutron to produce the radioactive change of one element to another.

VOA: special.2009.06.14

But radioactive waste is a serious unresolved issue.

VOA: special.2011.03.18

Florbetapir is a radioactive coloring agent.

VOA: special.2011.02.08

So,yes,there is a threat particularly of the use of radioactive material, although we have no specific evidence indicating any capability at this time."

VOA: standard.2009.05.01

But the acquisition of radioactive material for a so-called 'dirty bomb,' which is radioactive material that is dispersed with a conventional explosive device, that is not that challenging.

VOA: standard.2009.05.01