I had read a VPI article (Dave and Tracy Barker) that mentioned the ingestion of paper towel I thought it was odd but given the Barkers reputation for the science end of things I thought i'd ask my vet. She has worked around reptiles for a long time and learned under another vet she said that she has seen it four times in the past. No substrate ingestion is good but most are not as serious. Paper is also hydroscopic and reduces humidity as well. I felt that pointing out that others have had serious problems I thought it was a good thing to point out. It was mentioned that this was larger snakes and not hatchlings.
Ref. "BALL PYTHONS: History, Natural History, Care & Breeding" 2006 VPI library