Can guinea pigs eat string?
There is no harm in them chewing it as long as they don’t swallow it.
If they swallow it they are in big trouble, so it is not worth having it in their cage where they can access it.
If you do have any string accessible to them in their cage, it would be worth taking it out so they can’t reach it and there isn’t any risk of they swallowing it.
Once a guinea pig chews it then just keep an eye on them to see if there are any ill effects but they shouldn’t do more than chewing a little of it as it won’t be very appetizing for them.
For more things that guinea pigs can and can’t eat, check out our guinea pig food list.