It could be an issue if not careful. They're usually not long enough to get caught around anything though. They're meant to be individually knotted between each bead (and the beads are generally small, just a little bit bigger than a coco pop), and have a plastic clasp that breaks easily if put under strain. You're not meant to leave them on while they are sleeping/unsupervised, but most people wrap them around the ankle and then put a soak over it and put their babies down to sleep in sleeping bag where they can't get to it but still keep in on. TBH my DS has never noticed his - Never gone for it once.

It's normally something that you just leave on once you start using them, except for bath times etc. where they might get wet. I think they say you can use them from 3 months onwards. And they need "Recharging" every now and then, which basically is giving them a quick rinse with cold water and then rubbing them with a sunglasses cloth to get any build up of dead skin cells etc. off it that would get in the way of absorption. The Succinic acid in them wouldn't be finite either, so my guess is they would need to be replaced every 6-12 months if it is being worn for the health benefits rather than just fashion.