The Truth About SLS/SLES

Uncategorised
15 February 2025
Marista

This is an in-depth article searching for the truth about sls/sles and its place in our daily lives.

Introduction

Sodium Lauryl Sulfate (SLS) and Sodium Laureth Sulfate (SLES) are two of the most commonly used surfactants in personal care and cleaning products. These compounds are responsible for the foaming action in shampoos, toothpastes, body washes, and household cleaners. While they are highly effective cleansing agents, concerns have been raised about their potential health risks and environmental impact.

This comprehensive analysis delves into the history, chemical properties, uses, potential health effects, environmental concerns, economic impact, and regulatory status of SLS and SLES. The aim is to provide a well-rounded understanding of these surfactants, allowing consumers to make informed decisions about their use.

What Are SLS and SLES?

Sodium Lauryl Sulfate (SLS)

SLS, chemically known as sodium dodecyl sulfate, is an anionic surfactant that lowers the surface tension of liquids, allowing them to spread and penetrate surfaces more effectively. It is synthesized through the esterification of lauryl alcohol (derived from coconut or palm kernel oil) with sulfuric acid, followed by neutralization with sodium carbonate or sodium hydroxide.

As a surfactant, SLS effectively removes oil, grease, and dirt, making it a popular choice for both personal care and industrial cleaning products. However, its strong cleansing ability can also strip the skin of natural oils, potentially leading to irritation.

Sodium Laureth Sulfate (SLES)

SLES is a modified form of SLS, created by introducing ethylene oxide molecules in a process known as ethoxylation. This process results in a milder surfactant with reduced skin irritation potential. Chemically, SLES is known as sodium laureth sulfate, where “laureth” refers to the ethoxylated lauryl sulfate chain.

The ethoxylation process also introduces the possibility of contamination with 1,4-dioxane, a byproduct classified as a probable human carcinogen. However, regulatory agencies have set safety limits on its presence in consumer products.

History and Development

SLS was first introduced in the 1930s as a detergent for industrial use. Its strong foaming and emulsifying properties made it a valuable ingredient in household and personal care products, and it quickly became a staple in formulations for shampoos, soaps, and toothpaste.

The truth is that as consumer awareness of skin irritation issues increased, the industry developed SLES as a gentler alternative. By the mid-20th century, SLES became the preferred surfactant in many personal care products due to its lower irritation potential. Despite this, both SLS and SLES remain widely used, with ongoing debates about their safety and environmental impact.

Uses and Applications

SLS and SLES are found in a wide range of products due to their effective cleansing and foaming abilities. Their primary applications include:

Personal Care Products

Shampoos and Conditioners – Help remove dirt and oil from the scalp and hair.
Body Washes and Soaps – Provide lather that enhances cleaning efficacy.
Toothpastes – Act as foaming agents to distribute ingredients evenly and improve plaque removal.
Facial Cleansers – Assist in deep cleaning and oil removal.

Household and Industrial Cleaners

Dishwashing Liquids – Break down grease and food residue.
Laundry Detergents – Remove stains and dirt from fabrics.
Floor Cleaners and Degreasers – Cut through grime and oils on hard surfaces.

The concentration of SLS and SLES in these products typically ranges from 1% to 30%, depending on the intended use and formulation.

Potential Health Effects

Skin and Eye Irritation

The truth is that SLS is known to cause irritation, particularly in individuals with sensitive skin. Studies have shown that it can strip the skin of natural oils, leading to dryness, redness, and itching. A study published in the Journal of the American College of Toxicology found that even low concentrations of SLS (0.5%) can trigger irritation in some individuals.

SLES, due to its ethoxylation process, is considered milder than SLS. However, both compounds can cause mild eye irritation at higher concentrations, as noted by the Cosmetic Ingredient Review (CIR) Expert Panel.

Allergic Reactions

Although rare, some individuals may develop allergic reactions to SLS. The journal Contact Dermatitis has reported cases of contact dermatitis in patients exposed to SLS in cosmetics and topical medications. These reactions can include redness, itching, and inflammation.

Carcinogenicity and Long-Term Safety Concerns

Claims that SLS and SLES are carcinogenic have circulated widely, but the truth is that scientific research has not supported these claims.

SLS and Cancer – There is no direct evidence linking SLS to cancer in humans. Regulatory bodies such as the U.S. Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA) have deemed SLS safe for use in consumer products.
SLES and 1,4-Dioxane Contamination – The primary concern with SLES is the potential contamination with 1,4-dioxane, a byproduct of the ethoxylation process. The U.S. Environmental Protection Agency (EPA) has classified 1,4-dioxane as a probable human carcinogen, but manufacturers follow strict guidelines to minimize its presence in final products.

Oral and Systemic Toxicity

SLS has been examined for potential toxicity when ingested, particularly in toothpaste. While excessive ingestion may cause gastrointestinal distress, normal use in oral care products is deemed safe by regulatory agencies.

Environmental Impact

Biodegradability

Both SLS and SLES are biodegradable, meaning they break down relatively quickly in the environment. However, concerns remain about their production and disposal.

Water Pollution

Residues from personal care and cleaning products can enter water systems, potentially harming aquatic life. The accumulation of surfactants in water bodies can affect fish and other organisms by disrupting their natural protective barriers.

Sustainability Concerns

The truth is that SLS and SLES are derived from coconut or palm kernel oil, raising concerns about deforestation and biodiversity loss associated with palm oil production. Many manufacturers are now opting for sustainably sourced palm oil or alternative plant-based surfactants.

Economic Impact

Market Size and Demand

The global market for SLS and SLES continues to grow. According to a 2021 market report, the industry was valued at approximately $1.1 billion and is projected to reach $1.6 billion by 2028, driven by increasing demand for personal care and cleaning products.

Job Creation and Industry Growth

The production of SLS and SLES contributes to job creation in manufacturing, research, and sales sectors. Major companies like Unilever, Procter & Gamble, and Johnson & Johnson rely on these surfactants, boosting economic growth.

Shift Toward Sulfate-Free Products

As consumer awareness of sulfates’ potential irritancy grows, many companies are reformulating products using sulfate-free alternatives such as:

Cocamidopropyl betaine
Decyl glucoside
Sodium cocoyl isethionate

While this shift presents challenges for traditional SLS/SLES producers, it also creates new market opportunities for greener alternatives.

Regulatory Status

International Guidelines

U.S. FDA – Recognizes SLS and SLES as Generally Recognized as Safe (GRAS) when used within recommended limits.
European Chemicals Agency (ECHA) – Classifies SLS as an irritant but does not restrict its use in cosmetics.
Environmental Working Group (EWG) – Provides moderate concern ratings for SLS and SLES, advising caution for sensitive individuals.

Conclusion

The truth is that SLS and SLES remain fundamental ingredients in cleaning and personal care products due to their affordability, effectiveness, and foaming properties. While concerns over skin irritation, environmental impact, and contamination with 1,4-dioxane exist, scientific research supports their safety within regulated limits.

For individuals with sensitive skin or environmental concerns, sulfate-free alternatives offer a viable option. As the industry moves toward sustainability, the future of surfactants will likely involve continued innovation and the development of gentler, eco-friendly formulations.

SLS and our Products

The truth is that none of our products contain either SLS or SLES, it is completely sulfate free. We believe that since our products are aimed at healing the skin, it is best to avoid even potential irritants, so we opted for completely sulfate and paraben free formulations.

Feel free to shop our amazing products here and to investigate the ingredients we use here.