The food grade is safe for us. I am asthmatic so I am very careful about dust. You don't need to use a lot on the floor. I sprinkle it on the roosts, too, to kill any mites. It is finely ground up fossilized sea shells. The sharp edges cut the soft underbellies of insects, dehydrating them to death. I keep some in the feed so I don't get moth larva. You can apply it directly on your pets, I just try to apply it so the dust doesn't go directly in their face. I use it in my garden as well.
The non-food grade DE is full of silica. DO NOT use that! I spread it throughout my house years ago to control fleas and it my lungs were a mess!