13 Wildly Irresponsible Vintage Ads Aimed at Kids: #2. Gilbert Atomic Energy Lab
Yes, the Gilbert Atomic Energy Lab came with real live radioactive materials. It was supposedly low-level radiation and "completely safe and harmless!" though this is 1950 we're talking about. It's impossible to know if they were using the modern definition of the word "safe" or the Iver Johnson Revolver definition.
This toy was unofficially promoted by the U.S. government, which advertised a cash reward along with the toy to anyone who used the toy's Geiger counter to find uranium. There was presumably an additional reward for the first brave little boy to successfully use his Gilbert Atomic Energy Lab to kill a communist.