Nothing like Rid-X, etc - a sales gimmick. Bleach can be used, but sparingly. I know of people who use bleach on EVERYTHING - she's a germaphobic or whatever.
I was told never to make rag quilts for babies,especially, nor very small children as they have a habit of putting things in their mouth and sucking on them. Can you imagine the strings that child could pull out.
Take them to a laundromat as strings can jam up a washer, too, before it goes thru the hose. Someone told me all of this a long time ago and guess she had a bad experience, so she researched it.