Polysorbate 60 is a synthetic ingredient that is used in cosmetics and personal care products as a surfactant, emulsifier, and solubilizer.
Polysorbate 60 is produced by the ethoxylation of sorbitan. Sorbitan is the dehydrated form of sorbitol, a sugar alcohol that can naturally be found in some fruits. Ethoxylation is a chemical reaction in which ethylene oxide is added to a substrate (in this case, sorbitan). Sorbitan is reacted with 60 units of ethylene oxide (hence the 60 in the ingredient name). The final step is the reaction with fatty acids obtained from vegetable fats and oils, such as lauric acid, palmitic acid, stearic acid, or oleic acid. In addition to its function in cosmetics, polysorbate 60 can be used to prepare a wide variety of products in the food and pharmaceutical industries.
In cosmetics and personal care products, polysorbate 60 functions as a surfactant, emulsifier, and solubilizer.
As a surfactant, polysorbate 60 works by lowering the surface tension between two substances, such as two liquids or a liquid and a solid. A surfactant molecule contains one end that is hydrophilic (attracted to water) and one end that is lipophilic (attracted to oil). This allows surfactants to attract and suspends oils, dirt, and other impurities that have accumulated on the skin and wash them away. Due to these properties, polysorbate 60 can be found in many different cleansers, shampoos, and body washes.
Polysorbate 60 is also an emulsifier with an HLB value of 14.9. The HLB (Hydrophile-Lipophile Balance) value is an empirical expression for the relationship of the hydrophilic and lipophilic groups of a surfactant. An HLB of greater than 10 means that the substance is water soluble.
As an emulsifier, polysorbate 60 is often used in formulations that contain both water and oil components. Mixing water and oil together creates a dispersion of oil droplets in water (and vice versa). However, these two phases can separate if the product is left to settle. To address this problem, an emulsifier like polysorbate 60 can be added to the system to help the droplets remain dispersed. Emulsifiers improve the consistency of a product, which enables an even distribution of topical skin care benefits.
Lastly, polysorbate 60 functions as a solubilizer with a wide range of hydrophilic characteristics. A solubilizer helps other ingredients to dissolve in a solvent in which they would not normally dissolve. Specifically, polysorbate 60 helps to disperse oil in water as opposed to water in oil. Polysorbate 60 is an excellent solubilizer for essential oils and has good function as a wetting agent, viscosity modifier, anti-static agent, stabilizer, and dispersing agent.
The United States Food and Drug Administration (FDA) allows polysorbate 60 to be directly added to food as an adjuvant of flavoring agents or as a multipurpose additive. The safety of polysorbate 60 has been assessed by the Cosmetic Ingredient Review (CIR) Expert Panel. The Panel evaluated the scientific data and concluded that polysorbate 60 was safe as used in cosmetics and personal care products.
Despite the approval of polysorbate 60 by the CIR Expert Panel, there are concerns about the presence of ethylene oxide in this ingredient. This is because the process of ethoxylation may lead to contamination with 1,4-dioxane, a potentially dangerous by-product. 1,4-dioxane is a known animal carcinogen that penetrates readily into the skin. According to the National Toxicology Program, “1,4-dioxane is reasonably anticipated to be a human carcinogen.” It has also been linked with skin allergies. However, the potential presence of 1,4-dioxane can be controlled through purification steps to remove it before blending polysorbate 60 into cosmetic formulations.
References: Food Safety Commission, “Polysorbates”, 2007, Cosmetics Info, “Polysorbate 60”, Organic Consumers Organization, “1,4-Dioxane and Cosmetic Safety”.