DE is not as safe as many people make it out to be.
DE is made up of tiny crystalline structures. They are sharp, and over time, bed bugs (or other insects with exoskeletons) that come into contact with it die as they degrade from it.
However, DE is a significant inhalation hazard. While it can be applied safely (a very fine dusting barely visible to the eye only in areas where it will not get kicked up into the air), if improperly applied as we have heard about people doing, it can do significant damage to your lungs.
Also, often you will not see the results of the damage until years after exposure. So, unlike some chemical pesticides that cause immediate reactions to let you know you’ve been overexposed, DE doesn’t have a way to alert you that you’ve applied it improperly.
The DE that a consumer can buy off the shelf does not have the killing compound in it that the pest control techs have. As well as knowing how to properly apply the dust to be effective.
In some cases pest control professionals will not, for their own safety, treat properties that have been self-treated with DE until they have been vacuumed & cleaned of the dust.