I've never been afraid of books, what is in them or on them. There are people out there who are fearful of what may be on them. In particular some people won't use library books because they are afraid of the germs they may be carrying. Murphy has twice chewed up library books, Wolf Hall by Hilary Mantel and The Sense of an Ending by Julian Barnes. Truthfully, despite all the hype, I was not that impressed by Wolf Hall, but I did like The Sense of an Ending. Both times I said to the librarian I wasn't sure why my dog would suddenly choose these certain books (out of all the library books I have around) to chew up when this is not something she normally does. Both ladies said something like well you never know what people might have gotten on those books.... and left the rest to my imagination.
I've read that you can microwave books to sanitize them, though I've never tried. I've also read you can bake them in the oven to kill any germs; I'm guessing the way my mother used to bake soil to ready it for indoor plants.
No I've never worried about germs from library books; my worries are much more high-faluting than that.
For the record, Murphy has cost me with this book-chewing; it's a twenty dollar charge each time which I think is very fair and a small price to pay to support my on-going book addiction.