What about pencils? They're pretty much based on rubbing graphite on paper so that tiny graphene flakes break away and stick on the paper.

I thought it was lucky. Besides, it has been used in cosmetics for millennia.

Breathing ordinary soot is sub-optimal.

The set of things that are sub optimal to breathe is pretty wide ranging though. I agree that breathing soot is not great, but I don't think this is particularly because it contains CNTs, as much as because it is a fine particulate that can get into and block up alveoli. I can't think of any fine particulates off the top of my head that are particularly good to breathe in.