He also never, ever let anyone into the factory (until the events in the book), so public safety concerns weren’t an issue.
Now, the Oompa Loompas… they’re not naturally sterile, because they’re wearing clean suits later, but it could be that they are more buoyant so their safety if they fall in is less of an issue.
Wonka has magical technology. He’s probably perfectly sterilizing the chocolate later in the process.
He also never, ever let anyone into the factory (until the events in the book), so public safety concerns weren’t an issue.
Now, the Oompa Loompas… they’re not naturally sterile, because they’re wearing clean suits later, but it could be that they are more buoyant so their safety if they fall in is less of an issue.
Wonka has magical technology. He’s probably perfectly sterilizing the chocolate later in the process.