What Is Laureth-4?
Laureth-4 is a synthetic polymer that is used in many different cosmetics and skincare products to improve the texture and feel of a formulation. It is mainly used as a surfactant and emulsifier.
Laureth ingredients are synthesized through a process known as ethoxylation, a chemical reaction in which ethylene oxide is added to a substrate. In this case, the substrate is lauryl alcohol. Lauryl alcohol is obtained from lauric acid, a saturated fatty acid with a 12-carbon atom chain that can be found in palm kernel oil or coconut oil. The number associated with laureth-4 indicates the average number of repeating ethylene oxide units in the molecule. Laureth-4 is a clear, colorless liquid. As the numerical value of laureth ingredients increases, the viscosity increases until they become white, waxy solids.
the good:Laureth-4 is used to improve the texture and feel of products.
the not so good:Doesn’t provide any specific benefits to the skin.
Who is it for?All skin types except those that have an identified allergy to it.
Synergetic ingredients:Works well with most ingredients
Keep an eye on:There is some controversy over ingredients that are produced via ethoxylation as there is a risk of contamination. However, this process is highly regulated and the products are purified and tested for contaminants.
Why Is Laureth-4 Used?
In cosmetics and skincare products, laureth-4 functions as a surfactant and emulsifier. It can be found in products such as bath, cleansing, hair, and sunscreen products. It is also used in cuticle softeners, deodorants, and moisturizing products.
As a surfactant, laureth-4 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 or attracted to water and one end that is lipophilic or 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, laureth-4 can be found in many different cleansers and body washes.
Emulsifiers are necessary when a formulation contains both water and oil-based ingredients. It can be difficult to mix oil and water-based ingredients as they tend to separate and split. To address this problem, an emulsifier like laureth-4 can be added to improve the consistency of a product, which enables an even distribution of topical skincare benefits.
Is Laureth-4 Safe?
The Cosmetic Ingredient Review (CIR) Expert Panel, a group responsible for evaluating the safety of skincare and cosmetic ingredients, evaluated the scientific data. The Expert Panel concluded that laureth ingredients were safe as used in cosmetic products only when formulated to be non-irritating. This is because the laureth ingredients have the potential to irritate the skin.
Even though laureth-4 is considered a safe cosmetic ingredient by the CIR Expert Panel, there are concerns about the presence of ethylene oxide in this ingredient. As mentioned above, laureth-4 is created through ethoxylation, a process that produces 1,4-dioxane as a byproduct. 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 is controlled through purification steps to remove it before blending laureth-4 into cosmetic formulations.
References:Robinson, V, et al., 2010. ‘Final Report of the Amended Safety Assessment of Sodium Laureth Sulfate and Related Salts of Sulfated Ethoxylated Alcohols’, International Journal of Toxicology.