There was a news item from about 15-20 years ago about a child's playground jungle gym/swing set which was associated with symptoms of radiation sickness in the children who played on and around it. It turned out that the metal swing set was radioactive. Further investigation yielded the information that the swing set had been manufactured out of recycled dental office X-ray machines.
I call BS on that one. A dental or medical X-ray doesn’t make things radioactive. It can harm living tissue, particularly DNA, but doesn’t make it radioactive.
Perhaps the report was garbled by someone who didn’t know physics (like, a reporter, maybe?). The steel for the swing set could instead have come from a radiotherapy device that used radioisotopes. Such devices have gotten out into the wild; there was a story years ago of an abandoned medical clinic in South America where the locals broke apart a radioactive source, and several died from playing with the material.
Nope, 'fraid not. Dental x-ray machines use x-ray tubes to generate x-rays. No radioisotopes involved, nor any radioactivity generated. The culprits were pipeline weld inspection sources, which use gamma rays (not x-rays), and contain cobalt-60 or cesium-137 radioisotopes. As I recall, they had been stolen and sold as "scrap metal" in Mexico.