Sodium laureth sulfate, or SLES, is a synthetic compound made from a combination of sulfuric acid, ethylene oxide and sodium salt. It is commonly used as a foaming agent and emulsifier in the manufacturing of industrial products. It is also found in many personal care products, such as shampoos and moisturizers.
Description
Sodium laureth sulfate is a surfactant, which means that it contains both fat-soluble and water-soluble molecules. As such, it reduces the surface tension of water and other liquids to enable them to spread more easily over surfaces and blend together, or emulsify. This occurs through adsorption, which is the process of rearranging molecules from liquids so that they line up and adhere to the surface to form a film. This allows liquids to lather or foam in a manner similar to soap, which is why this compound is commonly used in shampoos and other personal care products, as well as detergents and some household cleaning products.
Production
Sodium laureth sulfate is synthesized from lauryl alcohol, a fatty alcohol extracted from the fatty acids of coconut or palm kernel oil. The process by which this synthesis takes place is called ethoxylation, which means that ethylene oxide is added to the fatty alcohol to act as a catalyst. This produces an ethoxylate, which is then reduced to a sodium salt. A related compound with similar properties but sometimes mistaken for SLES is sodium lauryl sulfate, or SLS. However, SLS is synthesized without undergoing ethoxylation, so it has a different chemical structure. In short, sodium laureth sulfate is the alcohol form of sodium lauryl sulfate.
Applications
SLES is widely used in the manufacturing of cosmetics and personal care products ranging from baby soap to skin lotions and sunless tanning products. It is also used to produce various household cleaners and industrial solvents and degreasers.
Safety Concerns
The safety of SLES has been a topic of controversy for years. In fact, rumors that this agent causes cancer have been persistently circulated through articles published on the Internet as well as in traditional print media. However, according to the chemical encyclopedia provided by HealthyChild.org, there is no evidence to confirm that SLES causes cancer. On the other hand, the organization also says that both the U.S. Environmental Protection Agency and the World Health Organization consider sodium laureth sulfate a possible carcinogen.
What has been established, however, is that the presence of sodium laureth sulfate in some consumer products may introduce low levels of 1,4-dioxane as a byproduct of the ethoxylation process. According to the Environmental Working Group, the National Toxicology Program classifies 1,4-dioxane as a known animal carcinogen, while the U.S. Environmental Protection Agency regards this compound as a probable human carcinogen.
Known Health Effects
Sodium laureth sulfate is known to produce skin and eye irritation in humans. If you experience irritation after using a personal care product containing this ingredient, discontinue use and consult your physician.
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