Actually from what I can find out, the Fresh water DE is food grade, and the dust is not any worse for humans than, road dust or grain dust, although it isn't recommended to inhale any of the three of them. People will take a teaspoon full of food grade DE every day for high blood pressure, cholesterol reduction, joint pain, re-grow hair, harden fingernails, and facial blemishes, and removal of liver spots on the skin. It is also used to de-worm your pets, and livestock, as well as shine your wife's silverware, and tooth polish.
You can use it to kill bed bugs in your bed or sprinkle it inside your home for ant and cockroach control.
It's the Salt water DE that is poison to humans and animals.