You must wear a dust mask when applying Diatomaceous earth, as it can irritate the mucous membranes. Once it settles after application, it won't hurt you.
While food grade Diatomaceous Earth is proven to be an effective and safe means of parasite control, Do Not Take Non-Food Grade Diatomaceous Earth Internally.
Diatomaceous Earth can be a valuable addition to our natural insect pest control arsenal. While it is generally safe for organic gardening, please always read and follow label directions.