It or any loose thread can wrap around a finger or toe cutting off circulation. On of my dd's got a thread inside a sleeper wrapped around just the tip of her toe as a baby.The tip of her toe was purple and the skin sloughed(?)off. Not permanent damage but had it been down farther she could have lost her toe.The thing with monofilament is you can't see it well.
That said, I have also used it with the "hand"quilting stitch on my machine and do like the wway it looks.