"talcum powder" is a natural mineral. mixed with "fragrance" it becomes "baby powder". my concern with corn starch is that it would react with moisture. in other words, it would go rotten and stink like a dead thing. for that reason, i'd stick with baby powder or talcum powder.

edit: asbestos & calcium are other examples of "natural minerals". there's not an absolute correlation between "natural" and "healthy"