It seems that our parents were — again — worried about absolutely nothing. Which makes sense… anyone contemplating such a move would quickly realize that if they did it on a mass scale they’d be tracked down in a day or two at most, and even targeting it at the one brat that has been terrorizing your pet iguana for years offers too much opportunity for discovery or for someone else ingesting the weaponized treat.
Sorry to ruin your fun, but poisoned apples apparently only happen in fairy tales.