A Guide to Sodium Laureth Sulfate: Is it Safe?

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Soap Suds - SLES
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Here’s a pop quiz: what do lip balms, shampoos, toothpaste, engine degreasers, and shaving creams have in common? 

If you answered they all have some chemicals in them. You’re only half-correct. The specific answer is sodium laureth sulfate.

Quick Navigation

What is Sodium Laureth Sulfate?
What other ingredients or compounds are related to SLES?
How does SLES work?
Where do you find SLES?

Is SLES dangerous?
What are the regulations for SLS?
SLS alternatives
Key takeaways

What is Sodium Laureth Sulfate?

Sodium laureth sulfate (SLES) is a chemical surfactant that can be dissolved in water and oil. It is derived from inexpensive raw materials and easily processed into a liquid compound that can be mixed into various products. 

detergent in a measuring cup

It was initially used as an ingredient for synthetic detergents that were manufactured as cheaper alternatives to old fashioned soaps.

Manufacturers and users discovered that it created thicker foam, produced stronger degreasers, and prevented soap scum. So, it became a popular ingredient.

Today, many manufacturers use it in a wider array of products, from cosmetics to cleaning products to food.

Many of the concerns about this compound stem from the fact that it is used in beauty care products and food and cleaning products. The thought of applying on the skin or ingesting an ingredient that is used to remove food stains from the carpet can be worrisome for some people.

What other ingredients or compounds are related to SLES?

SLES is derived from Sodium Lauryl Sulfate (SLS), which in turn can be extracted from petroleum, coconut oil, or palm oil. SLES is created through a process where ethylene oxide is mixed into SLS to make the compound safer and gentler. Because of these effects, SLES has replaced SLS in many products.

coconut oil in a clear glass container

Both SLS and SLES are sometimes written on labels as: 

  • sodium dodecyl sulfate, 
  • lauryl sodium sulphate, 
  • lauryl sulphate sodium salt, or, 
  • sodium n-dodecyl sulphate in some products. 

How does SLES work?

SLES has many uses besides allowing water and oil, two very opposing ingredients, to combine. It is also an effective foaming or wetting agent, cleanser, and emulsifier.

These qualities let shampoos and liquid soaps produce foam and clean surfaces. But it isn’t the foam that actually removes oil-based dirt. It is the SLES molecules that trap dirt and oil-based substances like excess sebum from the scalp or grease on the ground and allow it to be rinsed away. The foam can be compared to tiny hands that let the SLES do its work.

This is why SLES and SLS are incorporated into many cleaning products that aim to remove oily stains and dirt.

scientist at work

Since these compounds work well with water or oil, manufacturers add water-based or oil-based ingredients to create different types of the same product. For example, water-soluble sea salt (sodium chloride) is added to shampoo to add volume and shine to hair.

Its emulsifying or thickening properties are incorporated into certain food.

Where do you find SLES?

Unless you’ve been very conscious of the ingredients of products you buy, you may have been many products containing SLES. Read the labels of your household products and you will most likely read sodium laureth sulfate or its variants in many of them. 

Even products that proclaim to be “all-natural”, “eco-friendly”, or “organic” can contain SLES or SLS since technically its ingredients are extracted from plant products and other chemicals from nature. 

cosmetic products

These products include:

  • Cosmetic products: facial cleansers and exfoliants, hand sanitizers, hair dyes, lip balms, lotions, makeup foundations, makeup removers, nail polish, shaving cream, styling gels, and sunscreens.
  • Cleaning products: all-purpose cleaners, bath salts, body wash, car wash cleaners, engine degreasers, floor cleaners, laundry detergents, liquid hand soaps, mouthwash, shampoos and conditioners, toothpaste, and teeth whitening products.
  • Food additives: dry beverages, fruit juices, marshmallows, and ready-made egg mixes.

The concentration of SLS and SLES varies according to the function of a product. Food has minimal concentration while industrial cleaning products contain a high concentration of the compound. 

Is SLES dangerous?

men wearing protective gear

Scientists have been studying the safety of SLES and SLS. There have been reports of possible risks to users and the environment.

  • Health hazards

Large-scale groups like the European Union, Human and Environmental Risk Assessment (HERA), International Agency for the Research of Cancer, US Cosmetic Ingredient Review (CIR) Expert Panel, World Health Organization consider SLES and SLS as safe for incorporation in products. These compounds are also not included in lists of carcinogenic chemicals.

To understand the other concerns about this compound, we must look at how it is processed. 

To produce SLS, sulphuric acid is added to the lauric acid extracted from coconut or palm oil. Then sodium carbonate is mixed into the compound to neutralize it. Some reports have asserted that SLS and formaldehyde used in certain products create nitrosamines, which are carcinogenic. However, other scientists have pointed out that both chemicals do not contain nitrogen so it would be impossible for their reaction to lead to nitrosamines, which needs nitrogen to develop.

What is more possible is that some SLS and SLES may be contaminated during the manufacturing process by ethylene oxide and 1,4-dioxane, which are heavily linked to cancer. 

In particular, the California Environmental Protection Agency lists ethylene oxide as a potential developmental toxicant that may harm the nervous system or interfere with human development.

Meanwhile, 1,4-dioxane can form as a by-product when SLS goes through the ethoxylation process when it turns into SLES. Some products have been found to contain up to 300 ppm of 1,4-dioxane. A study has shown that this amount can already irritate some people.

SLS itself has been proven to cause skin and eye irritation. Although SLES is milder, it can still lead to an allergic reaction in some people. Generally, though, it is considered safe for use if it is rinsed off immediately and not used continuously. 

Also, one of the reasons that SLS has a bad reputation as a cosmetic additive and shampoo ingredient is that it dries the skin. In particular, SLS is found in aqueous cream products, which are recommended by health professionals to treat eczema and other skin conditions like dermatitis or psoriasis. This drying effect worsens the condition.

Additionally, since SLES attracts oil, it can strip off a body’s natural oils leaving behind dry or damaged skin and hair. Some people, though, have different reactions to the compound. Their hair and skin actually become oilier, which forces users to wash more often. 

  • Environmental hazards

SLES contaminated by 1,4-dioxane can turn the compound into a non-biodegradable matter. This means that it will not decompose for a long time, which could impact marine life since all wastewater eventually ends up in the seas.

beach pollution

Environmentalists are also concerned with the fact that SLS is derived from palm oil. Reports show that large tracts of rainforest land, as big as 300 soccer fields, are destroyed every hour to make way for palm oil plantations in Asia. This results in wider environmental and ethical issues like loss of biodiversity and tons of CO2 emissions released when rainforests are cut down and burned to convert them into plantations. 

What are the regulations for SLS?

The US Food and Drug Administration (FDA) lists SLS as safe as a food additive based on various conditions and specifications, including not exceeding 1,000 parts per million when used with egg white solids and that the label will identify it as an ingredient.

Canada prohibits ethylene oxide and 1,4-dioxane as ingredients for cosmetics and other consumer products sold in the country. However, there is no regulation for the removal of these substances from contaminated products. The US FDA highly encourages companies to remove the substance but does require this process. There is no way for ordinary people to check if this substance is present in what they buy.

SLS alternatives

With so many negative claims against SLES and SLS, some manufacturers recommend ammonium laureth sulphate, which closely resembles SLES, as an alternative surfactant. It has bigger molecules so it will not easily penetrate or irritate normal skin. It may still dry or irritate sensitive skin, though.

Sodium Coco Sulfate (SDS) is also becoming a popular alternative among soap manufacturers even though SDS uses the same process as SLS. Both start with the fatty acid from coconut oil and its reaction to sulfuric acid to create a sulfate. But, as stated earlier, SLS uses the lauric acid extracted from coconut oil while SDS uses the whole coconut oil, which makes SDS less irritating than SDS. 

Other alternative surfactants are:

  • decyl glucoside, 
  • disodium/sodium cocoyl glutamate,
  • lauryl glucoside,
  • sodium cocoyl glycinate, or,
  • sodium lauryl sulfoacetate, 

These compounds are considered milder because these will not strip the moisture from the skin yet still deliver the same clean results.

Organizations that promote natural products recommend soap and shampoo bars rather than liquid forms because the former usually do not contain SLES or SLS. Although these products do not produce as many bubbles as liquid soaps or shampoos, they still do the work of cleaning the skin or the scalp.

For healthier cleaning products, vinegar or lemon juice are recommended instead of commercial cleaners.

Key takeaways 

key point

The amount of SLS in cosmetics, household products, and food is limited by some laws. Studies have shown that its negative effects on health and the environment can be isolated and indirect. 

However, those who are still worried have an increasing number of alternative products to choose from. After all, everyone is surrounded by chemicals every day. What you consider as a safe or natural chemical is all up to you. Just read the label before you buy a product.

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