1,2-Hexanediol

Safety Information

United States (U.S.)

Expert Panel for Cosmetic Ingredient Safety:

The safety of pentylene glycol, 1,2-hexanediol and caprylyl glycol has been reviewed by the Expert Panel for Cosmetic Ingredient Safety. The Expert Panel reviewed the scientific data and concluded that these ingredients were safe as used in cosmetics and personal care products.

The Expert Panel reviewed data indicating that caprylyl glycol and the smaller compounds were easily absorbed into the skin. Additional studies suggested that these compounds are metabolized in the skin before they reach the systemic circulation. Repeated dose studies with these compounds have not resulted in significant adverse effects or effects on reproduction or development. These compounds were not genotoxic. Products containing the 1,2-glycol ingredients did not cause dermal irritation or sensitization.

Based on the data reviewed, the Expert Panel concluded that pentylene glycol, 1,2-hexanediol and caprylyl glycol are safe for use in cosmetic products.

European Union (EU)

Pentylene glycol, 1,2-hexanediol and caprylyl glycol may be used in cosmetics and personal care products marketed in Europe according to the general provisions of the Cosmetics Regulation of the European Union.

Resources

EU Cosmetic Ingredients Inventory

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Search the FDA Code of Federal Regulations

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1,2-Hexanediol

What Is It?

Pentylene glycol, 1,2-hexanediol and caprylyl glycol are 1,2-glycol compounds that vary only by the number of carbons. Each of these compounds has a hydroxyl group (-OH) on the first and second carbons. Pentylene glycol has 5 carbons, 1,2-hexandiol has 6 carbons and caprylyl glycol has 8 carbons in the carbon chain. In cosmetics and personal care products, these ingredients may be used in baby products, bath products, eye makeup, cleansing products, skin care products and hair care products.

Why Is It Used?

The following functions have been reported for the 1,2-glycol ingredients:

Hair conditioning agent
Caprylyl glycol preservative
Caprylyl glycol, pentylene glycol skin-conditioning agent
Emollient

Caprylyl glycol skin-conditioning agent
Miscellaneous
Pentylene glycol solvent
Pentylene glycol, 1,2-hexanediol

Scientific Facts

Pentylene glycol, 1,2-hexanediol and caprylyl glycol are all soluble in water, with water solubility increasing with decreasing carbon chain length. Although caprylyl glycol and pentylene glycol have been reported to have some antimicrobial activity, these ingredients may also serve to increase the antimicrobial activity of other preservatives.

1-Naphthol is a polycyclic phenol that functions as a hair colorant by reacting with other ingredients. Hair dyeing formulations belong to three categories — temporary, semi-permanent and permanent coloring of hair. The permanent hair dyeing formulations are often referred to as oxidative hair dyes which are generally marketed as two-component products. One component contains the compounds (precursors) that become the colorants and the other component is a stabilized solution of hydrogen peroxide.

The two components are mixed immediately prior to use. The precursors and peroxide diffuse into the hair shaft, where color formation takes place after the ingredients combine to produce the coloring mixture. The precursors are oxidized by the hydrogen peroxide to form the colorant molecules. These molecules are too large to escape from the hair structure. The hydrogen peroxide in the oxidative hair dye product also serves as bleaching agent for the natural pigment of the hair. The color that is formed depends on the precursors and direct dyes present in the dyeing solution, pH of the dyeing solution and the time of contact of the dyeing solution with the hair.