Coconut shell by itself is a natural non-toxic substance. It is actually one of the most widely used substrates used in keeping frogs (frogs are highly sensitive to toxins) because it is completely safe if ingested. I believe it is considered a wood product, and if so, it is exempt from CPSIA. Having said that, if any coatings, sealers or anything has been applied to the coconut, that would change things. Hope that helps. If you want to be 100% sure, I would start by contacting the manufacturer of you buttons.