Sodium Lauryl Sulfate (SLS) and Sodium Laureth Sulfate (SLES)


I don’t know about you but I am always suspicious of unpronounceable chemical names on labels. These 2 in particular are notorious and controversial as you will come across many sites saying that they cause no harm ( mainly personal hygiene product companies and others with a vested interest) and others vilifying them ( mostly bloggers ). To top it, many sites just quote others or add their own particular hot chilli mix.  So, could someone PUHLEASE clarify?

Sodium Lauryl Sulfate (SLS):

WHAT? AAAAThis is a man-made organic compound which is mainly used in detergents. It is a white or cream-colored crystal, flake, or powder or a clear to yellowish thick fluid with a faint odor.

WHY? It is a highly effective surfactant. What does that mean, you say? Well, basically that it cleans by helping to dissolve elements which aren’t water-soluble, like fats/oils. It also creates foam/lather as it “solubilizes air” in water. However, its ability to foam has a negligible effect on the functional performance of the product as this is mainly to satisfy consumer demand, fuelled by media making us believe that foam cleans. It is used also for its thickening effect. The properties go on- it acts as a dispersion agent to properly mix the ingredients in fragrance oils and body sprays and lastly, it kills microbes. Sounds pretty useful, huh? No wonder it is so widely used.

WHERE? It is found in higher concentrations in industrial products including engine degreasers, floor cleaners, and car wash soaps and in lower concentrations in toothpaste, shampoo, shaving cream/foam and bubble bath It is used as a dispersing agent in creams, lotions, as a cleansing agent in cosmetics, a whipping aid in dried egg products and food additives and has an essential function in commerce in leather softening and wool cleaning, metal processing, as an emulsifier, penetrant in glaze, paint remover and an antifoaming agent in solid rocket propellants. It may, also, be used as a penetrant, flocculating and de-inking agent in paper industry.

HOW?  SLS is derived from coconut oil. However, a very important ‘however’, it is made by adding sulfuric acid (made from sulfur taken from direct mining or processing of low-grade ores such as coal and petroleum) to the oil. A chemical reaction occurs where Hydrogen lauryl sulfate is produced which, being unstable, is then neutralized with sodium carbonate. Does this make SLS plant derived? Er…..kinda, the same way plastic is plant derived ( I mean, petrol is fermented plant material, right? Face palm)

SO? I have looked closely at about 10 human studies and skimmed many, many others and it seems that at worst, it is a skin irritant for humans, with one study ( A. Blondeel et al, 1978) stating that, “Among 242 patients suffering from eczematous dermatitis,…(a) Great number of allergic reactions to sodium lauryl sulfate (6.4%) was observed.” That’s 15 people among 242. Re the various animal studies that I looked at, the words “eye irritant” appeared but mostly, the phrase “no effect” was oft-repeated. However, what I found worrying was its effect on the environment for “The substance is toxic to aquatic organisms. It is strongly advised not to let the chemical enter into the environment.” (U.S. National Library of Medicine) And what do you think you wash into the waterways through your toothpaste and bubble bath and cleaning products etc….

Should you want to get rid of SLS, here are some alternative names for Sodium Lauryl Sulfate (or SLS) to look out for in labels:

• Sodium lauryl sulphate
• Sulfuric acid monododecyl ester sodium salt
• Sodium dodecyl sulfate
• Dodecyl sulfate, sodium salt
• Sodium lauryl sulfate ether
• Sodium dodecyl sulfate

…am sure that am missing a few in this list..

Sodium Laureth Sulfate (SLES):

SODIUM3WHAT? WHY? WHERE? SLS and SLES have pretty much the same properties (see above) with ONE major difference. Since, as we know from the above, SLS is a skin and eye irritant, to make it milder, it is put through a manufacturing process called “ethoxylation” and transforms into SLES. Ergo, the lauryl changing to laureth. Voilà!

With this change though, the alternative / trade names for Sodium Laureth Sulfate mulitply wildly. Am sure that I am missing some but here is the list:
• Alkyl Ether Sulfate
• Aquarex ME/ Methyl
• Carsonol SLS
• Dehydrag Sulfate
• Dodecyl Alcohol
• Dreft
• Duponal
• Emal 10
• Hydrogen Sulfate
• Irium
• Lanette Wax-S
• Laureth-8 carboxylic acid
• Maprofix 563/ NEU/ WAC/ WAC-LA
• Monogen Y 100
• Monododecylester
• Neutrazyme
• Orvus WA Paste
• Perklankrol ESD 60
• Perlankroll
• PEG-5 lauryl ether sulfate sodium salt
• PEG-7 lauryl ether sulfate sodium salt
• PEG-8 lauryl ether sulfate sodium salt
• PEG-12 lauryl ether sulfate sodium salt
• Polyethylene glycol 5 ( or 7/12/400/600) lauryl ether sulfate sodium salt
• Quolac EX-UB
• Sipex OP
• Sipon PD/WD
• Solsol Needles
• Sepanol T 28
• Sodium dodecylpoly (oxyethylene) sulfate
• Sodium lauryl sulfate ethoxylate
• Sodium polyoxyethylene POE(2) lauryl ether sulfate
• Sodium laureth-8 sulfate
• Sodium Diethylene glycol Lauryl Ether Sulfate
• Sodium salt
• Sodium laureth 5 ( or 7 /12) sulfate
• Sodium lauryl ether sulfate
• Steol-130, 230, 270, 330, 370 or 460
• Stephanol or anything with the word Stephanol and something else
• Sulfuric Acid
• Tarapon K 12
• Texapon K 12
• Trepenol WA
• 000151-21-3

You can check here for further chemical info on any of the trade or alternative names which I have listed above, for both SLS and SLES.

So WTF? I have been researching these 2 chemicals for weeks. I have seen good and bad. 2 studies ([Piret J et al 2000)  and (J.Piret et al, 2002)  have shown SLS to aid against the Herpes Simplex virus. Another study says that “nanosuspensions coated with SDS (Sodium dodecyl sulfate) may ultimately lead to improvements in the treatment of Toxoplasmic encephalitis and other cerebral diseases”. On the other hand, a study says that SLS affects the duration of mouth /canker sores and seems to increase the pain too. (YJ Shim et al, 2012). And so it goes on, with research after research on carcinogenicity, developmental or reproductive toxicity (with “no effects” being the result) and the picture I am getting is that the main threat seems to be of SLS as an eye and skin irritant  dependant on the intensity of detergent concentrations and length of exposure. Now you know why shampoo bottles always mention rinsing your eyes out as soon as the product gets in.

Be that as it may, my environmental concerns remain. What we wash out through our sinks/baths and showers end up in waterways in concentrations which are harmful to fish and other water fauna. Various studies show the harmful effects of surfectant molecules on water plants. Here is just one and here another one.

Another point to note is that most of the studies look at these chemicals in isolation – (more on this in the next post.) Also, no one seems to have researched the posible gradual and or, cumulative effects of long-term, repeated exposures of all the chemicals in personal care products, on us. Have you thought of the combined effect of all those chemials in all those things that you use daily in conjunction with the increasingly contaminated environments we live in and the heavily sprayed food we eat? Gulp!

Green and handmade ALTERNATIVES coming up, never fear!

DISCLAIMER: I have not been paid/advised by anybody to write/research the above. I have no links whatsoever to big pharma or any personal higiene product company. The views in this post are my own. I wish I could quote/mention the many, many articles that I read and do a meta-analysis but I am afraid that that would be beyond me at the moment.