I would never bite your head off or hope I wouldnt intentionally try to offend you in anyway, Im a nice guyFrom my own personal experience I had an incident years ago with loose substrate where a very fine piece somehow became wedged between the teeth and ended up with a sore a couple days later that almost looked like an abscessed tooth , it was such a small splinter it took 2 vet visits and to notice so now I dont use loose substrate at all in my racks, It was prob a one in a million chance that happened but it was enough for me to switch to paper towels, just me personally I would worry about something like that happening versus it being ingested