Polysorbates (inci)

Polysorbates are mixtures of partial esters of sorbitol and its anhydrides with higher fatty acids (C12-C18), copolymerized with approximately 20 moles of ethylene oxide per mole of sorbitol. Polysorbates are usually present in oily form.

The polymers are non-ionic surfactants and are used in cosmetic formulations (and pharmaceuticals) as surfactants and emulsifiers. Polysorbates are also used as solubilizers for slightly or not water soluble substances like essential oils, resins, etc. Otherwise they are used as wetting agents or emulsifiers in food, cleaning agents and water-insoluble drugs.

Trademarks are Tween®, Scattics®, Alkest® and Canarcel®.

The various types of polysorbate differ in the fatty acids used, the average number of polyoxyethylene units used and the degree of esterification. The two-digit number in the name of a polysorbate is explained as follows:

• The first number represents the main esterified acid: 2=lauric acid, 4=palmitic acid, 6=stearic acid, 8=oleic acid, 12=isostearic acid.
• The second digit indicates the type of esterification: 0 for a monoester with 20 polyoxyethylene units, 1 for a monoester with 4 or 5 polyoxyethylene units and the number 5 for a triester with 20 polyoxyethylene units.

For example, polysorbate 20 is the monoester of polyethylene glycol sorbitane with lauric acid (2=lauric acid) containing 20 polyoxyethylene units, polysorbate 60 is the monoester of polyethylene glycol sorbitane with stearic acid (6=stearic acid) containing 20 polyoxyethylene units.

The World Health Organisation (WHO) has proposed an Acceptable Daily Intake (ETD) also called ADI (Acceptable Daily Intake) of 0 to 25 mg/kg bw for the intake of ethoxylated sorbitan fatty acid esters.