[3] Diatomaceous earth, originally mined as "tooth powder" is a naturally occurring hydrated silica.
As a fine gel abrasive, frequently combined with softer calcium carbonate (from chalk) it helps to remove plaque.
[5] Hydrated silicas can form in nature through biotic processes primarily involving benthic microorganism activity in the oceans.
[6] In its pure form, as manufactured for toothpaste, it is an odorless, tasteless, white, gelatinous substance, which is chemically inert.
[8] A hydrated silica compound's effectiveness as a flame retardant is dependent upon the presence of chemically bonded transition metals, commonly iron and titanium[9] Hydrated silica is listed by the US Food and Drug Administration as "Generally Recognized as Safe" [10] Toothpaste: [1] Chemistry: [2][unreliable source?]