A guest post by Simon Mortimer.
Sodium Lauryl Sulphate (SLS) is a surfactant/detergent, these are essentially chemicals that have one end that likes water and another end that doesn’t! This means they break down water tension actually allowing water to effectively wet a surface and by attaching itself to grease/dirt they help lift this from skin or clothes or whatever surface they are applied in solution.
It is added to shampoo or similar rinse off products to perform these tasks, wet hair or skin and lift grease/dirt off their surfaces and allow the material you are trying to remove to be carried away in the water. It can cause irritation but so can almost any constituent of toiletries, there are alternative surfactants that can and are used but might be more expensive and some rinse off products are budget brands! The other issues are that it is found in rinse off products that are not supposed to be left in contact with skin, in fact the contact can be very transient and the concentration even in the product is generally low compared with more industrial cleaners containing the same material, and that is before you apply a large dilution factor in the sink or under the shower!
There are many articles linking SLS to skin irritation, mutagenicity and even cancer. There is no doubt that if you treat the neat material to unusual conditions like heating, or apply it neat and possibly repeatedly to skin in high concentrations (not found in toiletries) or leave it in your hair consistently then some of these might apply. But why would you do so, and do you?
Incidentally the carcinogen label is not related to the SLS itself but a trace impurity from its synthesis called 1,4 Dioxin. Dioxins are definitely nasty chemicals that are carcinogens but like with most of these relationships you have to consider concentration and exposure levels to really put their danger to ourselves into perspective. Levels of 1,4 Dioxin found are extremely low and well below any threshold that can even be considered hazardous or produce any adverse responses, and again once you use the products you add a massive further dilution factor. There are some common sense exceptions like those with existing skin problems particularly where skin thickness is compromised or even worse there are open sores etc but any sensible person in this condition would have sought medical advice and likely want to avoid any potential irritant, which means almost any toiletry and not just those implicated with irritancy.
So why SLS free? Marketing mainly! Of course if you have established a personal sensitisation to SLS or suffer as suggested above having a big label on the front telling you SLS is NOT inside is all very helpful, but really for the mainstream it is a fashion option, just like fragrance free, preservative free, colourant free. All of these are approved for use and considered safe in use over a long period of time. Except where typically small numbers have developed a personal sensitisation through their natural disposition and/or over exposure to specific chemicals or groups of chemicals. There is no real concern to the vast majority, just use the products sensibly and as directed, don’t bath in neat gel, don’t embalm your hair in shampoo and go to bed, don’t wash your face with perfume! If a shampoo is SLS free it must have an alternative surfactant in it otherwise it will be pretty useless as a shampoo! Now it is quite possible the alternative is considered “safer” however you define this term, perhaps has fewer trace impurities and has less toxicological studies built up around it, it could also have simply been used a lot less, for less time and so fewer people have looked actively to find out what they think is “wrong” with it, just wait 10 years and the google list for the new alternatives dangers might be just as long as the original material it replaced!
In sum remember that claims made against most constituents of toiletries are based on much higher concentrations than found in products and certainly as used; use products sensibly and as directed; if you develop an irritancy try a different brand but remember that this doesn’t necessarily mean a more expensive brand, it might be a case of simpler and cheaper is best! If you have a really serious reaction then seek medical advise because a skin reaction may be as a result of a reaction to food, fabrics, pets/animals or a whole host of other reasons other than your shampoo or face cream!
If you have any more questions for Simon simply ask in the comment box below and I’ll do my best to pass it on to him.