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Sodium Laureth Sulphate – What’s the fuss about?

February 24, 2009

Well, first of all it is important to know what we are talking about. Sodium Laureth Sulphate (also known as Sodium Lauryl Ether Sulphate/ sulfate) are the same thing.  Sodium Lauryl Sulphate (or sulfate) is slightly different.

Sodium Laureth Sulphate is made like this:

Coconut or palm oil* is extracted from the fruit > It is spit down into fractions  of fatty acids (these natural oils contain lots of different chemicals, each different one can be separated by distillation) > The lauric fatty acid is quite long  (12 carbons) it then gets changed to an alcohol by a REDUCTION reaction > Lauric Alcohol  can be used as a skin emollient (softener) on its own OR > Lauric alcohol can be reacted with Ethylene Oxide to make it surface active. It can then emulsify oil and dirt from surfaces such as the skin or hair.

Sodium laureth sulphate can also be made by taking Sodium lauryl sulphate and reacting it with ethylene oxide.

So is it natural? The majority of the surfactant is natural and is pretty much the same as when it was growing in the coconut or palm. However, the bit that makes sodium laureth sulphate useful to cosmetics is the ethoxylated head. This is produced synthetically.

Is it safe for us to use? We will see later.

Sodium Lauryl Sulphate  is made like this:

Like the above Sodium Lauryl Sulphate also comes from palm or coconut’s.** The same fraction is taken (the Lauric acid> lauric alcohol  but instead of being reacted with ethylene oxide, the head is reacted with sulfuric acid.  The head group is then neutralised to give the sodium salt.

So is this natural? It is actually more natural than the ethoxylated version above. That is because the lauric acid is natural and sulfuric acid is naturally occuring (although the sulfuric acid used in the reaction will be synthetically made for economic reasons).

So is this safe? Again, we will delve into this later.

The chemistry behind these two products may seem a little confusing to the average consumer but the important thing to note is that both of these chemicals are derived from natural sources but both are then reacted with synthetic chemicals to make them surface active.

Why are they used anyway?

Sodium laureth sulphate and sodium lauryl sulphate are two of the most cost effective surfactants for personal care manufacturing. They are added into products to help them to emulsify dirt. They do this by using their chemically modified heads to attract dirt from a surface and then drag it away in the foam that is created as a bi-product of the emulsification process.  SLES and SLS are both ANIONIC surfactants which means that they have a negative charge on their heads. Surfaces such as the hair, skin and often hard surfaces are positively charged. This means that the surfactants are attracted, like a magnet to the dirt!

How long have they been used for?

The  consumer focused surfactant industry really took off in the post war 1940’s although they were being used in the 1920’s and 30’s to some degree. Before that time surfactants had mainly been studied in medical fields and for heavy industry. Companies such as  Proctor and Gamble and Unilever started to develop more effective  products for cleaning the house, laundry and people. Liquid soaps and detergents became popular and shampoo’s such as P&G’s Drene really captured the public’s imagination.   Since then the use of surfactant containing products has skyrocketed. We now use soaps, shampoos, laundry products, dish washing detergents, hard surface cleaners and toothpastes all of which contain one or another type of surfactant. Sodium laureth sulphate and sodium lauryl sulphate can be found in all of the above.

OK, so these types of chemicals have been used for a while. What are the issues with SLS and SLES?

IRRITATION

Sodium Lauryl Sulphate – This is the more harsh detergent from a skins point of view. It is very good at stripping oil from surfaces and that includes your skin! There is no doubt that exposing yourself to too much of this stuff  will make your skin irritated and could, with repeat exposure  leave you open to sensitisation. It has also been linked to an increase in cankers or mouth sores in high risk groups.  However, in controlled doses this product should be safe for most people.  SLS is used in very low volume in products such as toothpastes and mouthwash. Your risk of irritation can be determined by your exposure and your own skin history.

Sodium Laureth Sulphate (Sodium lauryl Ether Sulphate) – This is milder than SLS (above) but can still cause skin irritation – See SLES MSDS.   SLES is not really used in oral products and is most usually seen in shampoos and bubble baths. The same precautions hold true here as for above. In normal useage contitions most consumers will be fine with SLES. SLES is often blended with another ingredient – Cocamidopropyl Betaine which has been shown to decrease the irritancy potential of SLES.  If your skin if extremely dry or you are suffering from a skin condition such as dermatitis or eczema you may want to discuss your bathing routine with a dermatologist as ALL surfactants will strip more moisture from the skin, not just SLS or SLES.

SLS is also irritant to the eyes and can cause permanent damage in high concentrations. However, in normal usage situations SLS should be perfectly safe. SLES is slighlty less toxic but care should still be taken.

TOXICITY

SLS – If you read a material safety data sheet for this chemical (MSDS SLS here) you will notice that it has some figures for toxicity expressed as LD50. This is an industry standard for working out how much of a chemical (in its pure state) an animal would have to ingest for it to kill 50% of the test subjects. In this case it was rats.  Well, a group of rats have to eat 1288mg of SLS for each Kg of body weight in order to kill 1/2 of the test group.  Based on this result SLS is classified as slightly toxic on the Hodge and Sterner scale. It gets a rating of 4 out of 6 where 1 is extremely toxic and 6 is relatively harmless.  See more here: Toxicity chart . SLS is also slightly toxic if it is breathed in.   Very few consumer products contain dry SLS so the exposure to SLS dust would be minimal for the consumer. Also SLS and SLES have not been found to bioaccumulate or build up in your body.

SLES – The SLES MSDS is here.  It is slightly less toxic than SLS, otherwise the same  conditions as SLS apply.

DOES IT CAUSE CANCER?

NO- Neither SLS or SLES have been proved to cause cancer.

Internet scare stories often say that SLS and SLES cause cancer.  What these stories are talking about is the contaminant 1,4-dioxane which may be present in small quantities in ethoxylated surfactants – SLES is an ethoxylated surfactant.  1,4-dioxane  is definately not good for health and has been linked to skin irritation, kidney failure and liver necrosis when people are exposed to high doses – usually via occupational exposure.  A safety assessment by NICNAS (Australian Chemical Notification body) is available to read here: Dioxin health risks by NICNAS

NICNAS concluded that 1,4-dioxane when handled correctly poses little risk to workers. NICNAS also looked at the amount of dioxane present in consumer cosmetic products. The level found was tiny – no more than 30 ppm. While the Environmental Working Group are looking into this further the general consensus is that while dioxane is not good, it is not present in great enough quantities to be of high concern.

The surfactants industry is aware of concern over dioxanes and many surfactant manufacturers are now taking steps to measure and reduce the amount of dioxane present in their surfactants. Some, such as Stepan list the amount of dioxane on the product MSDS.

Environmental Issues.

SLS and SLES are both readily biodegradable and are not expected to bioaccumulate.  See the Stepan environmental report below for more information.

SLS and SLES are also usually made in large scale production facilities and transported in bulk. While Realize Beauty has done no lifecycle analysis on SLS or SLES  the scale of manufacture of these ingredients may well make it more environmentally sound than the manufacturing of niche surfactants. RB will seek comment on this from industry representatives! Stay tuned.

So,in summary, should I ditch SLES or SLS?

At Realize Beauty we believe that only you can make that decision.  We have read evidence from Government Health Departments, the World Health Organization, the cosmetics industry and various consumer groups. The information that you can find on the internet can be at best alarmist and at worst completely false. While we have found that SLES and SLS can be irritating we have found no evidence that they contribute to anything more sinister.

SLES and SLS are skin irritants but they are no more irritant when put into a consumer product than many other ingredients (things like Tea Tree oil, retinol, alpha hydroxy acids are also irritating to the skin). Cosmetic scientists work to make their formulations as mild as possible – many test their products to support claims of “hypoallergenic” or “Tear Free”.

SLES and SLS don’t give you cancer.

SLES and SLS are being constantly monitored by surfactant manufacturers and the process is getting cleaner and cleaner to avoid by-products.

The cosmetic industry takes safety concerns seriously and is constantly researching into better solutions.

SLES and SLS are biodegradable. Stepan voluntarily submitted a dossier to the US environmental protection agency about Sodium Laureth sulphate. The dossier was submitted in 2006 and looked at the health and environmental hazards associated with this surfactant. A copy of the report is available here: Stepan and the EPA. A letter from PETA regarding the animal data used in this evaluation is also available here.

SLES and SLS are usually present in cosmetics and toiletries at levels ranging from 1% – 15% per active depending on the product (shampoo is at the higher end, toothpaste the lower).

We suggest talking to a dermatologist to find out what is best for your skin. If you (like me) have eczema you may want to opt for a more gentle cleansing routine or go soap free.

More reading and research.

Take time to read through the links in the document. You may also like those below.  If any new information comes to light about SLS and SLES we will be sure to let you, the Realize Beauty reader know.

Personal Care Product Councils response to internet rumors. In response to the 1998 e-mail.

The soap and detergents industry association

Queensland Governments health report on Sodium Lauryl Sulphate

*, **  While most manufacturers of personal care grade SLES or SLS are now sourcing raw materials naturally it is still possible that some surfactants are manufactured from synthetic sources such as petroleum. You would have to ask the maufacturer for confirmation on this.

12 Comments leave one →
  1. June 22, 2012 8:30 am

    No, you can’t make SLES by reacting SLS with ethylene oxide. The synthesis won’t work in that order. You have to first ethoxylate, then sulfonate.

  2. George Brousseau permalink
    December 22, 2014 4:35 am

    Thanks for the information. I bought a Body Wash product called Equate (Deep Moisturezer) and I started to have itching in both eyes. I read on this site what Equate could cause this irritation; the equate product contains Sodium Laureth sulfate that can cause irritations on the eyes. But the information that caught my attention is that this product has 25 ingredients. Do we need that many ingredients to clean and moisturize our body?.

    • RealizeBeautyEd permalink*
      December 22, 2014 7:45 am

      You don’t necessarily need much at all to clean a body but to make a safe, commercial product you can quickly end up with 25 or so ingredients. There is usually two preservatives to get a broad spectrum coverage, one chelating agent to help with micro protection, water as a carrier and wetting agent (very important) – so now we are up to 4 ingredients and we have only got preserved water! Oh and that water might need pH adjusting to make it more hydrating and so that the preservatives can work well. pH of the skin is at between 4-5.5 – water sits naturally at 7 so citric acid or equivalent brings the pH down. That’s 5 ingredients and still no product.

      Your cleaning agents are usually a mix of three or more ingredients which work synergistically to clean without stripping the skin. That’s the aim anyway. So there is another 3 things to add to the list to make a total of 8 ingredients.

      Then you have to consider how the mixture will thicken – we could use salt (Sodium Chloride) in some cases and in others we use either a natural or synthetic thickener – acrylates copolymer, cellulose, xanthan etc. Sometimes more than one is used for a better flow – rheology. Now we are up to around 10 ingredients.

      Then there are the ingredients that differentiate a product – moisturisers, natural actives, essential oils, vitamins and minerals. You could have any number of these to help improve the appearance of the skin.

      And lastly there is fragrance for fragrance sake. You might get away with one or two essential oils or night want to use one synthetic fragrance.

      So the minimum amount of ingredients you would typically find in a commercial liquid body wash would be around 12 based on the above.

      We don’t NEED them but just like we can get all the nutrition we need from a food replacement meal in a tube we ENJOY and prefer the combination both in terms of how it feels on the skin and how it sparks our imagination.

      Each to their own though.

      • December 22, 2014 10:09 am

        12 ingredients is still just half of 25. If you look at the formulas recommended in the trade journals, which are partly puff pieces promoting one or more ingredients from a given mfr., the number of ingredients would usually be in the single digits. You might get into double digits when the trade journal formulary entry lists simply “preservative” and you give the label declaration breaking that down to individual preservative components–sometimes including congeners as with the individual parabens. But if you get up to 15, you’re probably puffing up the label for the label’s sake with a lot of pinches of practically non-functional stuff.

      • RealizeBeautyEd permalink*
        December 22, 2014 11:39 am

        What I was trying to say is that you can easily get to 12 ingredients WITHOUT any marketing/ claims driven ingredients. Those formulations you see in the trade journals are starter formulations and very few brands just want nuts and bolts stuff – they want the product to do more and be more appealing.

        Whether these extra ingredients are just pinches of practically non-functional stuff or something more substantial is down to the individual brand and formulator to decide. I have known situations where a product contains a natural extract at 0.05% just so it can appear on the label and also situations where the additional actives make up more than 15% of the final product. Every situation needs to be viewed by its merits and it is very hard to judge that without a bit of background info.

  3. Rebecca permalink
    February 28, 2016 4:34 pm

    As SLS and SLES are often derived from palm oil, you might like to add this info in your environmental segment of your page. There are several websites with information on this concern. Here is one example: https://www.rainforest-rescue.org/topics/palm-oil

    • RealizeBeautyEd permalink*
      February 28, 2016 4:52 pm

      Hi Rebecca, This is a pretty old article now and I’m sure there is much more I’d change should I have the time. In general though I’ve written extensively about Palm oil and have it at the heart of my PhD – a quick search on the blog will show other things I’ve written. The issue with SLS and SLES is a bit more complex, these surfactants actually became MORE palm derived in 2010 as a result of pressure from the market for vegetable derived surfactants. Before then they contain a substantial proportion of petroleum derivative. So really it is a case of the general public being careful what they wish for. Here is a link to the launch of these new ‘natural’ surfactants:http://www.cosmeticsdesign-europe.com/Formulation-Science/Rhodia-launches-first-wholly-vegetable-derived-surfactant

      • February 29, 2016 5:21 am

        Interesting that one, thanks, with even the ethylene oxide being vegetable-derived. But “wholly vegetable-derived”? I’m sure the sulfonating agent is mineral! (Well, I guess they could use plant-derived sulfur, but I doubt they would.)

      • RealizeBeautyEd permalink*
        February 29, 2016 7:17 am

        You could be right there.

      • February 29, 2016 5:23 am

        Oof, mangled my URL above. I meant this one, linking to the page on my bubble mixture.

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