Ours are paper. I don't think it'd be a big deal if they ate them, though I don't know if the dye in them might make them sick. They are back out now and being good so far.
We had streamers in the hallway when Kim graduated from college. Eclipse was determined to get them. He was still pretty small so we would pick him up to bat at them. When one finally fell down, we taped it to the back of a chair for him to play with. They were a thick malamar material so no worries about him eating them.