Chlorothymol

What Is It?

Cresols (p-Chloro-m-Cresol, Mixed Cresols, m-Cresol, o-Cresol, p-Cresol) and Isopropyl Cresols (Chlorothymol, Thymol, o-Cymen-5-ol, Carvacrol) can all be in the form of crystals. These ingredients may be used in bath, skin, personal care and hair products, hair dyes and mouthwashes.

Why Is It Used?

In cosmetics and personal care products, the Cresol and Isocresol ingredients are used as cosmetic biocides/preservatives and/or fragrance ingredients. Follow this link for more information about how preserviatives protect cosmetics and personal care products.

Scientific Facts

Cresols are methylphenol compounds which are naturally occuring or synthetic. For example, Thymol, also called isopropyl-m-cresol, thyme camphor or thymic acid, is obtained from the essential oil of the herb thyme, Thymus vulgaris. It is also produced synthetically. Thymol is effective as an antifungal preservative. Thymol has a characteristic pungent odor and a somewhat caustic taste.

Safety Information

The Food and Drug Administration (FDA) permits the use of Thymol as a direct and food additive (as a flavoring substance) and as an indirect food additive (for use in paper an paperboard in contact with food). The safety of Cresols and Isopropyl Cresols including Thymol has been assessed by the Cosmetic Ingredient Review (CIR) Expert Panel. The CIR Expert Panel evaluated the scientific data and concluded that Sodium p-Chloro-m-Cresol, p-Chloro-m-Cresol, Chlorothymol, m-Cresol, o-Cresol, Isopropyl Cresols, Thymol, o-Cymen-5-ol and Carvacrol were safe at concentrations up to 0.5% in cosmetics and personal care products; however, the available data were insufficient to support the safety of p-Cresol and Mixed Cresols for use in cosmetic and personal care products.

CIR Safety Review: The CIR Expert Panel concluded that the toxic effects of cresol and isopropyl cresol ingredients were observed at doses higher than would be available from cosmetics and personal care products. In order to ensure that these ingredients are used at a level that would not cause any adverse effects, the CIR Expert Panel recommended an upper concentration limit. Data were available to demonstrate that m-Cresol and o-Cresol when tested at 0.5% do not cause chemical leukoderma (skin whitening). It may be that Sodium p-Chloro-m-Cresol, p-Chloro-m-Cresol, Chlorothymol, m-Cresol, o-Cresol, Isopropyl Cresols, Thymol, o-Cymen-5-ol and Carvacrol do not cause chemical leukoderma at concentrations higher than 0.5%, but data were not available to support that possibility. Therefore, a concentration limitation of 0.5% was chosen to ensure the absence of a chemical leukoderma effect. p-Cresol was shown to cause depigmentation of hair and possibly the skin. In addition, there was a concern that p-Cresol may be a strong allergen. There were insufficient data for the CIR Expert Panel to determine a safe use level that would not sensitize or lighten the skin for p-Cresol and Mixed Cresols (which contains p-Cresol). Therefore, the CIR Expert Panel considered that the available data were insufficient to support the safety of these two ingredients in cosmetics. Studies are needed which would demonstrate a concentrations of use of p-Cresol and Mixed Cresols that would not result in skin whitening.

Link to FDA Code of Federal Regulations for Thymol

In the European Union, p-Chloro-m-Cresol, Sodium p-Chloro-m-Cresol at concentrations up to 0.2% and o-Cymen-5-ol (4-Isopropyl-m-cresol) at concentrations up to 0.1% are allowed to be used as preservatives (see Annex VI).

Link to the EU Cosmetic Regulation: 
http://europa.eu/legislation_summaries/consumers/product_labelling_and_p…