Hydrated silica, which is used in many toothpastes.
Hydrated silica consists of the chemical compound silicon dioxide in a form that binds to water molecules. The water content of this compound can vary, and if silicon dioxide dissolves completely in water, the compound is called silicic acid. In nature, hydrated silica occurs in various forms, for example as diatomaceous earth and as opals. It can also be manufactured and usually contains enough water to produce a white jelly-like substance that is tasteless and odorless and can be used as a mild abrasive and to increase the viscosity or thickness of various products. This substance is non-toxic and is commonly used in toothpastes, cosmetics, and body products.
Hydrated silica is sometimes used in whitening toothpastes.
Silicon, also known as silica and having the chemical formula SiO 2 , is a metalloid, meaning it has some of the characteristics of metals and some of the characteristics of nonmetals. Not to be confused with silicone, which is a polymer. Silicon is one of the most common chemical elements on Earth and, in the form of silicon oxide, is found in sand, quartz, flint, granite, and many other minerals.
The proportion of water molecules in hydrated silica varies.
In the form of hydrated silica, it is also found in the cell walls of a type of algae called diatoms. Diatomaceous earth, a type of soft sedimentary rock mined for a variety of industrial uses, consists of hardened sediments of fossilized diatoms. It is also found in the form of opals, a type of gem that consists of silicon dioxide with a water content that is usually 6 to 10%.
Hydrated silica is often added to toothpaste to help remove plaque.
A very common use for manufactured hydrated silica is as an ingredient in toothpaste, prized for its abrasive properties that help remove plaque and calculus. In a normal toothpaste, hydrated silica is often ground until the grains are about 8 microns in diameter. For use in specialty whitening toothpastes, the grains are slightly larger, typically 10 microns in diameter, giving a more abrasive effect. In older types of toothpaste, diatomaceous earth was used for the same purpose. This substance is also used in various personal care products, such as skin creams, deodorants, and facial scrubs.
Skin creams and facial scrubs may contain hydrated silica.
In chemistry, hydrated silica is sometimes called an inert substance, meaning that it is not chemically reactive. This substance is not known to be toxic or carcinogenic, and has been classified as generally recognized as safe (GRAS) by the US Food and Drug Administration (FDA). It is important not to confuse this type of silica with crystalline silica, which is a toxic substance.