THIMEROSAL

Name / description

Thiomersal; Mercury((o-carboxyphenyl)thio)ethyl, Sodium Salt

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Function(s) of this ingredient in cosmetic products

PRESERVATIVE

Protects cosmetic products from microbial spoilage

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Origin

synthetic/plant

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Occurrence in cosmetics

Is at present practically no longer used.

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Background information on use in cosmetics

Preservatives protect cosmetic products against microbial spoilage and hence make a major contribution to consumer health. Preservatives are particularly required in cosmetic formulations containing water, because microorganisms can colonise and reproduce in an aqueous (water-containing) environment. Cosmetics often contain more than one preservative substances and these preservative systems act simultaneously against different bacteria, yeasts or moulds. Each of these substances has been comprehensively tested and assessed for safety (individually and in combination). Manufacturers always use only the lowest possible effective concentration in a product so that an optimum shelf life and safe application are ensured.

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Information on safe use

In accordance with the EC Cosmetics Regulation (Regulation (EC) No. 1223/2009), which applies to the entire EU market, preservatives means substances which are exclusively or mainly intended to inhibit the development of microorganisms in the cosmetic product. Annex V of the Regulation defines the substances which may be used as preservatives in cosmetic products. In this so-called positive list of preservatives, maximum concentrations are defined for the use of these substances in cosmetic products as well as the permissible uses. Preservatives are examined in respect of their toxicological safety prior to their approval in Annex V and undergo extensive tests. Manufacturers must prove the health safety in extensive scientific studies.

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Why are we talking about it?

Thimerosal contains mercury. It is also accused of inducing allergies (sensitising). The facts: Thimerosal is used in vaccines, sometimes in higher concentrations than those used in cosmetic products. The French health authorities and the World Health Organisation (WHO) consider that this preservative is safe at these concentrations, including by injection. In cosmetics, the concentrations are lower, and the exposure much lower (thimerosal is only used in low concentrations, only in certain categories of eye cosmetic products, which are applied in very small quantities), which allows for a margin of safety greater than the required margin of safety. As with any toxicant, the dose makes the poison, and the very low dose of mercury to which the consumer is exposed by using cosmetic products containing thimerosal is safe. Thimerosal can be sensitising to some people, but cases of allergies are rare. Key points to take away: Although the presence of mercury in thimerosal may seem unusual, the dose to which the skin is exposed via cosmetic products is very low and considered to be without risk. The use of thimerosal, which is highly regulated as for all preservatives, is therefore considered safe, including by the WHO.

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Further information

For the clarification of a suspicion of a contact allergy this substance can be routinely tested in the epicutaneous test at the dermatologist.

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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.