Etymology Coined by Pierre Curie and Marie Curie in 1898 as French radio-actif, equivalent to English radio- + active.
1
Exhibiting radioactivity.
As a matter of fact many of our best drinking waters have all sorts of unspecified qualities. Burton water, for example, is radioactive by Beetham's standards up to the ninth degree.1917, H. G. Wells, “The First Vision”, in The Soul of a Bishop:
Today, no one would intentionally smear radioactive materials on their face, but in 1933, the dangers of radioactivity were not yet fully understood.2020 March 8, Jacopo Prisco, “When beauty products were radioactive”, in CNN:
2
Figuratively, Rare Dangerous and disgusting, particularly of people or ideas.
Even sleazy tactics and his radioactive mouth may not be able to contain this debacle.
It was as though he was possessed of an invisible aura repelling incoming bodies. ‘Look. No one wants to be associated with him now. He’s become radioactive.’2009, Michela Wrong, It’s Our Turn to Eat: The Story of a Kenyan Whistle Blower:
2 more examples
And while Biden’s other nominees have done little to provoke Republican backlash thus far, [Neera] Tanden is “radioactive,” as Sen. John Cornyn (R-Texas) put it.2020 November 30, Burgess Everett, Caitlin Emma, Theodoric Meyer, quoting John Cornyn, “Joe Biden's 'radioactive' nominee”, in POLITICO, archived from the original on 02 Dec 2020:
If, by some miracle, Democrats hang on to one or both houses of Congress this November, it will be because of Cawthorn, Paul Gosar, Marjorie Taylor Greene, Lauren Boebert and other would-be G.O.P. candidates trying to be just like them — the Radioactive Republicans.2022 April 4, Gail Collins, Bret Stephens, “Which ‘Radioactive Republicans’ Are We Betting On?”, in The New York Times, →ISSN, archived from the original on 06 Apr 2022: