Does Sodium Lauryl Sulfate (SLS) Cause Cancer?

I did a review last week on EverPure Shampoo and Conditioner, and their main focus for marketing is the fact this product line is Sulfate Free.

The Campaign for Safe Cosmetics and those that believe their information, have been disseminating the myths that sodium lauryl sulfate or sodium laureth sulfate, will cause cancer. These statements are ambiguous at best and provide little evidence or research to support this theory.

When dealing with the facts, confusion abounds and then gets twisted to making these ingredients as one in the same or similar versions producing the same results. This in fact is not accurate and with so much misinformation out there, it is wise to take a closer look at these two ingredients and understand the differences, because they are different.

Yes they are both foaming agents and yes they are related, and yes you’ll find them in personal care products for cleansing teeth, hair and skin, so they are typically going to be found in bubble bath, toothpaste, shampoo, facial wash and shaving cream.

But let’s look at the discernible differences:

Sodium Lauryl Sulfate

This is a surfactant which works well as an emulsifier for removing dirt and oil from our hair or skin. It is used widely in toothpastes for getting that foaming action for cleaning our teeth and is shown to be very safe. It is also used as a laxative in enema application.

This ingredient has no link to cancer at all, but is shown to be an irritant on the skin in concentrations of 2% or higher in formulations. Problems with this ingredient, it’s irritating properties is equated in high doses when coming in contact with skin or eyes, such as in the MSDS for manufacturing, and again as so many who have read my articles in the past, realize the correlating factors are not the same when used in minute ratios of skincare products.

The Cosmetic Ingredient Review lists this ingredient as safe with a qualifier. What this means is that it is safe for use in rinse off products without restrictions to ratio, but in leave on products, the concentrations of less than 1% are what is determined to be safe and preventing skin irritation. This information is updated as of July of this year.

Confusion Or Deliberate Deception

Sodium lauryl sulfate has also been linked to causing cancer due to the production of nitrosamines. This became the ongoing myth that was perpetuated out of this discovery in shampoos containing miniscule nitrosamine contaminants back in the 1970’s. What was actually being used as a surfactant at the time was the ingredient ethanolamine lauryl sulfate, and it was believed that this ingredient contained the contaminant in shampoos. Manufacturers were responsive by removing the offending ingredient from their formulas and replaced it with SLS. Now the stigma remains due to the facts being misconstrued by the Campaign for Safe Cosmetics and others.

This information, though not readily available, is probably how the truth was spun into the perpetual myth, taking us farther from the actual truth. They are not one in the same at all. An article written in the Washington Post in 1998 touches on the subject of shampoos and gives and in depth report by Joe Schwarcz who is a professor of chemistry at Vanier College and McGill University, both in Montreal. He is the 1999 winner of the American Chemical Society’s James T. Grady-James H. Stack Award for Interpreting Chemistry for the Public.

In regard to ethanolamine lauryl sulfate, the CIR qualifies this ingredient as “safe only” as a rinse off product. So it is not recommended to be left on the skin in any amount and you certainly won’t find it in shampoo anymore. So this debate is rather moot at this point in time.

What I do find odd is that the skin deep database does not have any information in regard to SLS, just the campaign for safe cosmetics article on their theory based on antiquated misinformation which is misstated from another ingredient since removed from shampoo. It seems that if the science is shown and the evidence points to the contradiction as our skincare products improve, they do less than nothing in clarifying these facts. It is more important to keep that link to cancer in the back of consumers minds since this further promotes their agenda.

Update 12/15/10: In returning to the skin deep database, it appears either the program wasn’t working the day I did this research or I typed in something incorrectly, but SLS is rated in the skin deep database and they clearly have this earmarked for being a cancer causing agent.

However, they provide no actual study as always, showing proof of the allegation only that it is a primary skin irritant, again making no reference to the dose and is based mainly on reactionary markers on animals. Also I would like to point out that studies, when referenced, pertained to “in vitro” and not “in vivo” and all other studies are so outdated, it is ridiculous, and in many cases as they pertain to humans as far as an irritant, again no reference to dose. One can only surmise this info is only created based on manufacturing knowledge with workers exposed at higher levels of skin contact. Unfortunately, the consumer will not understand the differences.

As always Skin Deep Database remains antiquated and vague! Sorry for any confusion this may have caused to my readers.

Now as to ethanolamine lauryl sulfate, Skin Deep rates this ingredient all over the map for HAZARD! Warning…warning….. Danger Will Robinson! (Lost in Space for those that remember…hmm interesting metaphor) They literally are showing testing on the eyes of rabbits dating back to 1946. Not only is this antiquated, but the dose is described as “small”. What does this mean? The ambiguity is astounding and is the repeated pattern for the database! This teaches the consumer nothing but only serves to promote fear.

I was pleased to see an article written by Tree Hugger, part of the Discovery channel, basically denounce this ongoing urban myth in regard to sodium lauryl sulfate. I don’t always concur with some of what they write about, but in this regard they got this one right and are being extremely forthcoming and fair in this article. Many of the links for click through in the article are broken however, but I have provided others within this one.

Sodium Laureth Sulfate

Is similar to SLS but is identified as SLES. The difference is that sodium laureth Sulfate is the ethoxylation of dodecyl alcohol. This ingredient, like SLS is extremely safe to use and has been determined safe up to 50% in the emulsion. Due to it being used as a primary surfactant in facial cleansers, shampoos and toothpastes, it is also considered a rinse off product, so contact duration with skin is minimal.

Again, it can be an eye and skin irritant, but so can anything that comes in contact with mucous membranes not designed to be used in the eye, mouth or nose. Many natural ingredients will do the same thing.

How about a squirt of lemon juice in the old kisser…how do you think your eye would enjoy that?…..or perhaps a burp of Pepsi up the nose?….That’s my fave!

Where the concern comes from is during the ethoxylation process, 1,4-dioxane may be produced in negligible amounts. Many wish to believe this is a carcinogen and the research is insufficient at this time. In fact the CFSC goes so low and is completely shameless, as to correlate this supposed toxin and others, as being in baby shampoo, and has built an entire campaign around this reprehensible scare tactic toward mothers.

Toxicology research by the OSHA, NTP, and IARC supports the conclusions of the Cosmetic, Toiletry, and Fragrance Association (CTFA) and the American Cancer Society that SLES is not a carcinogen.

The U.S. Environmental Protection Agency classifies 1,4-dioxane to be a probable human carcinogen (having observed an increased incidence of cancer in controlled animal studies, but not in epidemiological studies of workers using the compound), and a known irritant (with a no-observed-adverse-effects level of 400 milligrams per cubic meter) at concentrations significantly higher than those found in commercial products.

So again, let’s be cognizant of the differences, such as animal versus human studies, and not allow the fear mongers to have us examining every label that comes off the store shelves out of paranoia created by them.

Urban Myth Spread Through Email Marketing

An example of this type of disingenuous marketing has been attributed to mass emails which are believed to come from MLM companies in support of selling you their, supposedly safer products. Some natural and organic companies are equally guilty of promoting this propaganda. One email in particular was addressed directly by the American Cancer Society.

They make the unfounded cancer claims in each email, or that SLS has been used to clean garage floors….so what!….SLS is a powerful surfactant (wetting agent) and detergent. It has industrial uses because it is a detergent which exerts emulsifying action, thereby removing oil and soil.

Are you going to use SLS at this concentration on your face or hair?….NO….would the industrial strength be used at this level in personal care products?…. a resounding NO… the comparison is ridiculous and adds no merit to this argument.

Many ingredients in the personal care products industry have multiple uses other than going on our bodies. Does this make them less safe because something we use on our bodies may also be exceptional for cleaning a dish or being a lubricant on mechanical machinery?

Silicone for instance is also used as a mechanical lubricant, but the properties of this fantastic ingredient for slip and its’ derivatives, proved to be excellent detangling agents for hair. Furthermore it provides slip in lotions and cosmetics for ease of application, and became the replacement for many mineral oil based emulsions.

A weird example: Cola products, due to their acidic nature, is used to remove blood from streets after an accident…… it is used as a rust remover and is able to dissolve corrosion on machine parts. It erodes the enamel of our teeth and removes grease and other stains from our clothes, yet we pour it down our gullet on a regular basis….so just curious, are you concerned….or are you going to stop drinking cola products based on this evidence?

A cola habit contributes to diabetes, weight gain, de-calcifying of teeth and bone, linking it to osteoporosis and to ulcerative colitis. So this is not a product I consume since childhood, but that is my choice and for those that love it, will continue to consume it despite the unhealthy evidence related to cola products.

The Final Analysis

In regard to either ingredient, Sodium Lauryl Sulfate or Sodium Laureth Sulfate, these are both fantastic at getting hair and scalp clean due to the intense foaming nature of these ingredients. Many people like this fact, since it also gives a nice volume to hair, and followed by a good conditioner can counteract some of the dryness caused by these ingredients.

But for those that don’t like these ingredients, there are many other alternatives available such as those derived from coconut. And since SLS and SLES do a great job, yet can be drying or irritating to delicate skin when used in facial care products, it is best to avoid them in this application. They can also have a stripping or drying effect on hair, leaving it with lackluster color, fly away or brittle.

So if you are looking for an alternative form of surfactants to the SLS or SLES in products, there are many to choose from. The removal of these otherwise safe ingredients for personal care products is based solely on the fear that has been perpetuated throughout the internet and sadly misinformed media, whereby creating a consumer demand for sulfate free products. Unfortunately, this has further created the ongoing spread of misinformation and its’ supporters are taking full advantage of this fact.

Personally, we don’t use it in our skincare products solely for the reasons I stated above… can be drying and possibly irritating to some skin types, but not based on the supposition of causing cancer. Other naturally derived surfactants have simply been shown to be far more gentle than SLS and SLES. But the beauty of this industry, you still have choice….for now!


  • Chemists Corner

    You know what I’ve never understood about the whole SLS, SLES bad publicity, why doesn’t Ammonium Lauryl Sulfate or Ammonium Laureth Sulfate ever get mentioned?

    Do people just assume they are the same thing or do they think they are different and ALS, ALES are fine?

    The majority of the top shampoos in the United States are based on ALS / ALES not SLS.

    • Katherine

      Apparently the Skin Deep database likes those two ingredients since they only give a score of 1. ALS and ALES are probably not mentioned since no one, including EWG or CFSC are raising any red flags. And as I stated in the article SLS is getting blamed for a problem which was caused by ethanolamine lauryl sulfate dating back to the 70’s.It is clear to see who leads the march on ingredients…when alarm bells go off with CFSC, then everyone with a vested interest to slam an ingredient uses their non science based rhetoric to spread the disinformation in support of selling their products or pushing their agenda. If CFSC has no discernible evidence to claim against an ingredient, it is pretty much left alone and not addressed. So this is why these two ingredients fly under the radar and are more readily accepted as better ingredients to use in place of SLS and SLES.

  • Dene Godfrey

    A great post , as always, Katherine. I particularly like the cola example – I may steal that one to use for myself! :-)

    • Katherine

      Thanks Dene, I just updated my info in a comment, since I was in error on one referenced point, and now it is corrected! Feel free to use the pepsi example, I thought it was kinda fun!

  • Katherine

    This is an update: In returning to the skin deep database, it appears either the program wasn’t working the day I did this research or I typed in something incorrectly, but SLS is rated in the skin deep database and they clearly have this earmarked for being a cancer causing agent.

    However, they provide no actual study as always, showing proof of the allegation only that it is a primary skin irritant, again making no reference to the dose and is based mainly on reactionary markers on animals. Also I would like to point out that studies, when referenced, pertained to “in vitro” and not “in vivo” and are so outdated, it is ridiculous, and in many cases as they pertain to humans as far as an irritant, again no reference to dose. One can only surmise this info is only created based on manufacturing knowledge with workers exposed at higher levels of skin contact. Unfortunately, the consumer will not understand the differences.

    As always Skin Deep Database remains antiquated and vague! Sorry for confusion in my initial article. It will be updated to reflect this latest information.

  • Erinthecitymouse

    Your article gave me a thought. Can people with the correct ingredient information create a database that could become a well known reference? I know that EWG is government funded etc. I am not sure about skin deep or the other one so i will not speak to that. It is unfortunate that we cannot stop them at this time but maybe there is another solution.
    I hear very well meaning people reference these misnomer databases and feel so upset and don’t know what to do because i am just some little person with good and real information, but to go against these agencies, who would believe me???….

    • Dene62

      @ETCM (love the name, btw), the problem is that it is not possible to create a database that would reflect the true safety of products – Skin Deep (funded by the EWG, incidentally) is classic proof of this. I don’t know if you have seen my article on Skin Deep on this site, but you can search for it here. The basic principle is that no manufacturer would knowingly place an unsafe product on the market. In the EU, a safety assessment, by a competent scientist, is required before the product can be sold. This means that Skin Deep is redundant in the EU anyway – the product has been deemed to be safe by someone who actually knows what they are talking about!

      We are all “little people”, but by contributing to sites like this we can make a difference, if only a small one! Please feel free to refer anyone relying on Skin Deep to my article on here (Skin Deep – Scratching Below The Surface).

    • Katherine

      Hello Erinthecitymouse, Sorry for the delayed response, but I don’t always find time to return to monitor my articles placed at PCT.

      I am grateful to Dene responding to you so quickly, and I really have nothing more to add since he has stated it quite well.

      I will state this however, please don’t be afraid to stand against those that are out to destroy an entire industry with their unfounded and non science based information. Trust me, you are not alone, and when stating the facts, that is all the protection you need. Stand with others in pursuit of the actual science, and you’ll be surprised at the numbers of us out there working diligently to stop the spread of the EWG’s disinformation. To reiterate Dene’s comment, refer those inquiring minds to PCT. You’ll find plenty of support here for what you are trying to accomplish. We are here for anyone who wishes to understand science in it’s entirety, not the cherry picked pieces by EWG which is mostly founded based on environmental issues something which does not extrapolate to personal care products.

      Thanks for stopping by, and I hope you revisit often in the future.

  • Meryam Ben

    sls is caner so att evey one

  • J Rook

    While I appreciate the contributions from biased industry reps below, there are numerous studies regarding the toxic effects of Sodium Lauryl Sulfate including liver damage and mutation effects on mammalian cells. You narrow focus on Cancer certainly calls into question the comprehensiveness of the research regarding carcinogenic effects and further research is warranted. However, minimizing the strength of the causal relationship in terms of cancer should not be used as a means to ignore the extensive list of toxic effects of chemicals such as Sodium Lauryl Sulfate. There are better alternatives, some of which you touch on at the end of your piece. I’m sure a conclusion that “Sodium Lauryl Sulfate doesn’t cause cancer so it is Safe” is equally as misleading and inadequate.

    • Dene Godfrey

      @ J Rook – I can’t help observing that your comment might have been better without the snide reference to “biased industry reps”. To which of the contributors do you refer, specifically? And please can you quote this “extensive list of toxic effects” for SLS? Your comment sounds rather vague, as you actually state “extensive list toxic effects of chemicals SUCH AS SLS”. It would be better to be much more specific, as you seek to undermine the article, but without any real evidence quoted; just vague accusations. Just two examples does not comprise an extensive list, and I would be interested to see any evidence that the use of SLS in cosmetics can lead to liver damage. I quote from the UK CTPA “thefactabout” web site”:
      “The safety of SLS (sodium lauryl sulphate) has not been questioned by the European Commission, nor its expert advisory committee (the Scientific Committee on Consumer Products, or SCCP), nor by any of the member states. The safety and toxicity of this ingredient was reviewed in 1983 by the Cosmetic Ingredient Review (CIR) Expert Panel of the USA. They concluded that SLS was safe for use in cosmetic products. This conclusion was re-confirmed by the CIR in 2002, after an additional 250 scientific research studies were considered.
      Although prolonged contact with high concentrations may cause irritation, this is not seen at the low concentrations of SLS used in cosmetics and personal care products, such as shampoos and toothpastes; these have a long history of in-use safety.”
      So it would appear that the independent expert panel employed by the EU Commission to make decisions on the safety of cosmetic ingredients are wroing in their assessment. perhaps you should contact them with your information?

    • Katherine

      I too would like to see these studies in relation to SLS since your assertion that there are mutation effects on mammalian cells does not track according to the Ames Test: as per their findings.

      SLS is not carcinogenic when either applied directly to skin or consumed. A review of the scientific literature stated “SLS was negative in an Ames (bacterial mutation) test, a gene mutation and sister chromatid exchange test in mammalian cells, as well as in an in vivo micronucleus assay in mice. The negative results from in vitro and in vivo studies indicate SLS does not interact with DNA.

      If you have something which contradicts these findings, yes please do share it with us.

  • Lia

    To me personally, it doesn’t matter what a “study” may or may not find to be dangerous. I have severe eczema on my hands and psoriasis on my scalp and arms. If using a product that has SLS makes me break out and bleed…. then study or not, I’m not going to use the product that contains SLS. Period. To me (and I know I am different then other people) SLS = painful bleeding so I don’t use anything that contains SLS.
    as far as the Cola example, ummm… You could have used another example. lol. That isn’t the healthiest beverage either. just saying. But this was an interesting article. Thanks for your imput. Have a great evening.

    • Katherine

      Thanks Lia for stopping by and I am glad you enjoyed the article. You also make a great point in regard to what this ingredient does to your skin. Based on this, of course avoid it at all costs as I would any ingredient that gave me fits. And that is the beauty of our industry, no pun intended, that we are free to choose from a multitude of products providing us the clear choice as to what we determine as safe based on the evidence, not supposition or myths created by the blogosphere or NGO’s deciding for us without any actual science.

      As far as the Cola example, well you know, I like a little drama, not too much, but it is fun sometimes to add a bit of shock value to make a point. ;~)