http://en.wikipedia.org/wiki/Diatomaceous_earth
barngodess - I keep fish and have used the pool filter kind as well in tanks. The problem with it for mammals is the Silica that is in it. It will cause Silicosis. Fish don't breath it.
It just sits in the filter. When you itroduce it to the air of something breathing is where the problem comes.
Your dogs, cats, chickens, excetera will not fall over dead upon usage.
The symptoms would develop over time. The severity and the time it takes to rear it's head would be proportionate to how often, and how much you use.
I know wiki is not always reliable but the link aboveand the text on it gives more info, some of which is below, and it's pretty well correct on this entry.
The saltwater (industrial) 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. Food-grade diatomite generally contains very low percentages of crystalline silica. Diatomite produced for pool filters is treated with heat, causing the formerly amorphous silicon dioxide to assume its crystalline form.
In the United States, the crystalline silica content in the dusts is regulated 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.[3]
