STEARETH-21

Name / description

Steareth-21; Stearyl Alcohol, Polyethyleneglycol Ether (on average 21 units of -CH2-CH2-O-)

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Function(s) of this ingredient in cosmetic products

CLEANSING

Cleans skin, hair or teeth

SURFACTANT - CLEANSING

Surface-active agent to clean skin, hair and / or teeth

SURFACTANT - EMULSIFYING

Allows the formation of finely dispersed mixtures of oil and water (emulsions)

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Origin

synthetic

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Background information on use in cosmetics

Polyethylene glycols (INCI: PEG-...) are poly condensation products of ethylene glycol, or polymerisation products of ethylene oxide. The number added to the name refers to the mean number of ethylene oxide units in the substance. The consistency of the PEG derivatives is increasingly solid with a growing degree of polymerisation. PEGs with a mean molar mass of up to 600 g/mol are liquid, up to 1,000 g/mol wax-like and from 4,000 g/mol solid wax-like substances. By mixing solid and liquid components, products of a creamy consistency are obtained which are used as water-free and water rinse-off bases. With growing molar mass water solubility and hygroscopicity (ability to absorb moisture) of the polyethylene glycols decrease. Surfactants are so-called detergent substances and have a major significance in cosmetics for the cleansing of the skin and hair. Surfactants are substances which, based on their molecular structure, are able to reduce the surface tension of a liquid. In this way it is possible that two actually not mixable substances, such as oil and water, can be finely mixed. Because of their properties, surfactants have manifold uses in cosmetics: they can cleanse, produce foam and act as emulsifiers and mix substances with one another. In shampoos, shower gels and soaps, surfactants are, for instance, used to wash fat and soil particles with water off from the body. Surfactants are also used in toothpaste. Here they promote during tooth cleaning the rapid and full dissolution and distribution of the paste in the mouth. The surfactants used in cosmetic products are primarily produced synthetically on the basis of vegetable raw materials. Surfactants are often used in combination to equally meet all desired requirements – like dissolution of soil and formation of foam in combination with a good skin tolerance – in the best possible manner. Through a skilled combination of a surfactant – viewed on its own – with unfavourable skin tolerance but a very good soil removal property with a very mild, skin protecting surfactant altogether a product with good cleansing properties and the same good skin tolerances is obtained. Emulsifiers are often used in cosmetics as excipients. They allow actually unmixable components like oil and water to be brought in a permanently stable emulsion. In this way both aqueous and oily care and active ingredients can be used in one and the same product in cosmetics. Emulsifiers are able to do that since their molecules consist of a lipophilic and a hydrophilic part. In this way they can reduce the interfacial tension which actually exists between two incompatible substances like fat and water. Emulsifiers are, more particularly, used for creams, lotions and cleansing agents. At present emulsifiers are, however, more than only excipients which keep an emulsion stable. Fatty acid esters on the basis of sugar, lecithin or glycerin monodistearate contribute, for instance, to improving the moisture balance of the skin and are, therefore, also considered as cosmetic active ingredients.

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Information on safe use

Claudia Fruijtier-Pölloth: Safety assessment on polyethylene glycols (PEGs) and their derivatives as used in cosmetic products. In: "Toxicology" (2005), No. 214, P. 1-38. Publisher: Elsevier Ireland Ltd.

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Belongs to the following substance groups

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Regulating cosmetics

Cosmetics Ingredients are subject to regulation. Please note, different regulations may apply to cosmetic ingredients outside the EU.