Is it safe to use spit balls (jelly balls) in my water pipe as a diffuser?

I got these rubbery-like jelly balls that expand when they’re put into a bowl of water. I’m not sure what they’re made of but the package says that they’re non-toxic. I was just wondering if the smoke coming from the pipe could possibly melt them? Or release toxic fumes? On YouTube I watched a couple videos of people already using them as diffusers, but I really want to know if they’re safe.