METHYLISOTHIAZOLINONE

Name / description

Methylisothiazolinone (MI, MIT), 2-Methyl-4-isothiazolin-3-one, 2-Methyl-2,3-dihydroisothiazol-3-one

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Function(s) of this ingredient in cosmetic products

FRAGRANCE FUNCTIONAL

Functional ingredient (excipient) of perfume oils and / or flavours

PRESERVATIVE

Protects cosmetic products from microbial spoilage

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Origin

synthetic

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Occurrence in cosmetics

Various rinse-off products, also in combination with methylchloroisothiazolinone or chloromethylisothiazolinone (CMIT / MCI)

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Occurrence in other products

Paints, glues and cooling lubricants, household and industrial cleaning agents, stationery, lubricants, wood care and water treatment agents

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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. Fragrances or mixtures of fragrances are often referred to in the cosmetics area as "perfuming agents" or "perfume oils" or "parfum oils". On the cosmetic products they are declared with the INCI name "PARFUM". These are undiluted individual substances or their mixtures which originate from natural raw materials or can be produced (semi-) synthetically. They are starting materials for the production of perfume, eau de parfum, eau de toilette, eau de cologne and other perfumed cosmetic products. The average content of fragrances amounts in perfume to 15-30 %, in eau de parfum to 10-14 %, in eau de toilette to 6-9 %, in eau de cologne to 3-5 % as well as in skin creams, shampoos, hair and deodorant sprays to approximately 0.2-1 % and approximately 1-3 in deodorant sticks. The perfume oils include essential oils, resinoids and absolutes. The sources are, amongst others, flowers, leaves and stems, fruits and fruit peels or roots of plants; woods, grasses or herbs, needles, resins and balsams. Moreover, only compounds isolated from natural products such as aldehydes, ketones, esters, alcohols etc. are used (geraniol, citronellal, citral, eugenol, menthol) as well as semi-synthetic (citronellol, geranyl acetate, jonone) and synthetic scents (eg phenylethyl alcohol and linalool) are used. Scents of animal origin such as musk and ambra are only rarely used.

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Information on safe use

Methylisothiazolinone is used in cosmetic rinse-off products up to a concentration of 15 ppm as preservative. The European Scientific Committee for Consumer Safety (SCCS) assessed the use of methylisothiazolinone in rinse-off products in its opinion of December 2015 on the basis of extensive scientific data as safe. 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?

Methylisothiazolinone (MIT) and methylchloroisothiazolinone (MCIT) have a sensitising potential, i.e. they can induce an allergy. The facts: MIT and MCIT have been widely used as preservatives in cosmetic products to replace the unjustly criticised parabens. In view of the resurgence of skin allergy cases and the data confirming the sensitising potential of MIT and MCIT, cosmetics industry representative bodies at European level have recommended limiting their use since 2013 (1). In this context, the industry decided of its own accord to limit MIT use and alerted scientific experts on the grounds for this decision. MIT and MCIT are now banned in leave-on cosmetic products, and severely restricted in rinse-off products (much shorter contact time) (2, 3 and 4). The authorised concentration in rinse-off products is considered to be low enough to avoid inducing allergies in non-sensitised people (5). Key points to take away: Current restrictions on the use of MIT and MCIT allow for a safe use in rinse-off cosmetic products with regard to possible allergy induction in a non-allergic person. As with any ingredient in a cosmetic product, the presence of MIT and/or MCIT is indicated on the packaging. Thus, people who are already sensitised to MIT or MCIT can avoid using cosmetic products containing them. Sources: (1) https://cosmeticseurope.eu/files/3614/7634/5470/Recommendation_on_MIT.pdf (2) Cosmetic Products Regulation (EC) No 1223/2009; Annex V (3) European Scientific Committee on Consumer Safety (SCCS): SCCS/1521/13: https://ec.europa.eu/health/scientific_committees/consumer_safety/docs/sccs_o_145.pdf (4) European Scientific Committee on Consumer Safety (SCCS): SCCS/1557/15: https://ec.europa.eu/health/scientific_committees/consumer_safety/docs/sccs_o_178.pdf (5) Cosmetic Ingredient Review: Amended Safety Assessment of Methylisothiazolinone and Methylchloroisothiazolinone as Used in Cosmetics, 2021: https://pubmed.ncbi.nlm.nih.gov/34259066/

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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.