If you click the link in your original post you will be able to click on the description of the product under which is says this is the same product as food grade DE. That being said you can use it if you like but I don't use it, from all the reading I have done it seems it is not useful, many people on this forum use it and claim it is helpful but I feel many of them are wasting their money and use it so they can feel warm and fuzzy about not using pesiticides to treat their birds. Also DE is only effective when dry, I don't know about you but my chicken coop isn't always the driest place on earth, I leave windows open and have plenty of ventilation, the birds make water messes on the floor and the feces contains moisture all of which will effect the properties of DE.
Also as mentioned DE is a silica product and they claim the food grade is safer than filter grade but neither one is safe to be breathing into your lungs, don't worry about the chicken, a chicken doesn't live long enough to contract silicosis from breathing that garbage in, you will have that opportunity. This sort of thing gets trapped in your lungs much like breathing in concrete dust on a construction site, it is very dangerous to expose yourself to that for long periods of time and will potentially cause lung disease. Chicken coops are dusty places and unless you wear a respirator when you work with your birds you can be effected.
