Breathing any dust is not good for you or your lizard.
Lizards need calcium and it is usually in the form of calcium carbonate.
Too much of anything is not good for you or your lizard.
I think it is just part of the general debate around keeping lizards like should they be kept on sand (they live in the desert and there is not much turf let alone astroturf there) and I would suspect there are lizards living happily in areas of marble, chalk and other forms of calcium carbonate.