🌿 Plant-derived cleaning products, made in the USA since 2012

Sodium Laureth Sulfate

Sodium Laureth Sulfate

What It Is

Sodium laureth sulfate (SLES) is an anionic surfactant produced by ethoxylating sodium lauryl sulfate -- adding ethylene oxide units to the SLS molecule to create a larger, less irritating compound (CAS 9004-82-4 for the generic; specific CAS numbers vary by ethoxylation degree). The "eth" in the name stands for ethoxylated. SLES is typically sold with 2-3 moles of ethylene oxide per molecule (SLES-2 or SLES-3). It is a clear to slightly hazy viscous liquid that functions as a cleanser, foaming agent, and emulsifier.

Common Uses

SLES is the most widely used surfactant in the global personal care industry. It appears in shampoos, body washes, hand soaps, bubble baths, facial cleansers, dish soaps, and household cleaners. It is preferred over SLS in many formulations because it delivers similar cleaning and foaming performance with less skin irritation. SLES is available in both plant-derived (coconut/palm) and petroleum-derived forms, with the plant-derived versions increasingly common in consumer products.

How It Works

SLES works through the same surfactant mechanism as SLS -- it reduces surface tension, forms micelles, and traps oils and dirt for rinsing. The ethylene oxide chains added during manufacturing make the molecule larger and more water-soluble, which reduces its ability to penetrate the skin's lipid barrier as deeply as SLS. This is why SLES causes less irritation: the ethoxylation makes the molecule too bulky to disrupt skin proteins and lipids as aggressively.

The tradeoff for this gentleness is minimal. SLES retains most of SLS's cleaning power and foam generation while being noticeably milder in clinical irritation tests. This combination of performance and mildness is why SLES dominates the shampoo and body wash market.

Safety and Regulation

The CIR Expert Panel concluded that SLES is safe as a cosmetic ingredient in current practices of use and concentration (CIR, 2010 reaffirmation). SLES is substantially less irritating than SLS in clinical patch tests, though it can still cause irritation at high concentrations or with prolonged exposure.

The primary safety concern specific to SLES is 1,4-dioxane contamination. The ethoxylation process can produce trace amounts of 1,4-dioxane, a probable human carcinogen (EPA Group B2). The FDA does not set a specific limit for 1,4-dioxane in cosmetics but has noted that manufacturers can reduce it to negligible levels through vacuum stripping. California's Proposition 65 lists 1,4-dioxane as a known carcinogen. Actual 1,4-dioxane levels in finished SLES-containing products vary by manufacturer; FDA monitoring surveys have detected levels ranging from undetectable to approximately 20 ppm depending on supplier controls and the use of vacuum stripping during manufacturing (FDA).

SLES is readily biodegradable. The ethoxylation does not significantly impede environmental breakdown.

Why Natural Flower Power Does Not Use It

Natural Flower Power does not use sodium laureth sulfate in any product.

SLES is a well-performing surfactant with a lower irritation profile than SLS, and the 1,4-dioxane concern is manageable through manufacturing controls. Our exclusion is based on two factors. First, we exclude all sulfate surfactants as a category -- it is a formulation standard we set when we built our product line, not a response to any single safety concern. Second, the ethoxylation process introduces a potential contamination vector (1,4-dioxane) that our current surfactant choices simply do not have. Decyl glucoside, cocamidopropyl betaine, and sodium alpha olefin sulfonate deliver the cleaning performance we need without ethoxylation and without the associated monitoring burden.

Related Ingredients

Sodium lauryl sulfate (SLS) is the non-ethoxylated precursor to SLES, with stronger cleaning power but higher irritation potential. Ammonium lauryl sulfate is a related sulfate surfactant with a different counterion. Decyl glucoside is a nonionic, plant-derived surfactant that Natural Flower Power uses as an alternative to sulfate-based surfactants. Sodium alpha olefin sulfonate is the primary anionic surfactant in NFP's formulations -- sulfate-free and not produced through ethoxylation.

Sources

  • Cosmetic Ingredient Review (CIR). "Amended Final Report on the Safety Assessment of Sodium Laureth Sulfate and Related Compounds." International Journal of Toxicology, 2010 reaffirmation.
  • U.S. Environmental Protection Agency. 1,4-Dioxane Technical Fact Sheet. epa.gov.
  • U.S. Food and Drug Administration. “1,4-Dioxane in Cosmetics: A Manufacturing Byproduct.” fda.gov.

Disclaimer

The information provided in this ingredient guide is for general educational purposes only. It is intended to explain how individual ingredients are commonly used in formulated products and does not constitute medical, safety, regulatory, or professional advice.

Ingredient function, safety considerations, and regulatory status can vary depending on formulation, concentration, product type, and intended use. Individual sensitivities may also vary. Always refer to product labels, safety data sheets, and applicable regulations for complete and current information.

Regulatory frameworks and requirements may change over time. References to regulatory context reflect general conditions as of the date noted and are not a claim of approval, certification, or compliance for any specific product.

This content does not replace professional evaluation, testing, or compliance review and should not be used as the sole basis for product selection or use decisions.