Hmm, another thing for parents of young kids to watch.
DD1 was a terror for putting things in her mouth long beyond the age when she should have grown past that stage. I went in to check her one night when she was six years old and noticed her mouth was moving. Watch for a moment then finger in and pulled out a button! She was fast asleep. Could have choked on it, it wasn't a tiny one that would have gone down!
I gave her a right blasting about safety next morning. Probably scared her witless, but it killed off the putting things in mouth habit.
I still shudder when I think of that night!