I had heard great things about food grade DE and using it with my chickens, unfortunately for me, it hasn't been the panacea that folks claimed it to be. I developed dry skin and painful sores on my hands, and my nose would start to bleed whenever I sneezed. I finally did the research that I should have done before hand, rather than relying on word of mouth from pseudo-experts. This is what I found: The absorbent qualities of diatomite can result in a significant drying of the hands if handled without gloves. The flux-calcined form contains a highly crystalline form of silica, resulting in sharp edges. The sharpness of this version of the material makes it dangerous to breathe and a dust mask is recommended when working with it. The type of hazard posed by inhalation depends on the form of the silica. Crystalline silica poses a serious inhalation hazard because it can cause silicosis. Amorphous silica can cause dusty lungs, but does not carry the same degree of risk as crystalline silica. Natural or dried diatomite generally contains very low percentages of crystalline silica. Diatomite produced for pool filters is treated with high heat (calcining) and a fluxing agent (soda ash), causing the formerly amorphous silicon dioxide to assume its crystalline form. The crystalline silica content of the dust's particulate is regulated in the United States by the Occupational Safety and Health Administration (OSHA), and there are guidelines for the maximum amounts allowable in the product and in the air near the breathing zone of workers. Since I can't keep dust masks on my birds, this stuff has been banished to the garbage bin. Now me and my birds are doing much better.