Diatomaceous Earth (DE) - Food Grade Diatomaceous Earth is a natural sedimentary rock formed from the 30 million-years-old chalky remains of microscopic algae-like plants. DE has a variety of uses that fall into several different categories, and is often used as a facial exfoliator, as a household cleaner and deodorizer, and it can also be used as a natural pesticide. What does Food Grade mean for Diatomaceous Earth? Our Food Grade DE has not been treated with high heat and contains less than 1% of crystalline silica, and it considered GRAS by the FDA. GRAS uses for DE include to be used in food processing as a filtration aid as a component of composite filtration media. However, there are other forms of DE commonly sold for other uses that are not appropriate for use in the same manner of food grade DE. For example, pool grade DE has been treated with high heat and contains a very high level of crystalline silica, which is very dangerous for the health of humans and animals and should be avoided for anything but its intended use (pool filtration).