Emulsifier and foaming agent

Sodium Lauryl Sulfate (SLS) is an emulsifier and foaming agent used in many cosmetic products and industrial cleaners. It can be found in soaps, shampoos, toothpaste, body washes and laundry detergent. SLS, or sodium dodecyl sulfate, sulfuric acid, monododecyl ester, sodium salt, sodium salt sulfuric acid, sodium dodecyl sulfate, aquarex me or aquarex methyl (to keep things easy!), is produced a fatty acid called lauric acid, that usually comes from petroleum oil.

SLS is actually a pesticide and herbicide and it is toxic to aquatic organisms, so it makes you wonder what it is doing in your shampoo, right? It is a known skin and eye irritant and because it strips oils and moisture from the skin, it can dry out your skin. Scientists use SLS to irritate the skin of animals and human volunteers to test the effectiveness of products on irritated skin. Furthermore, according to the Journal of the American College of Toxicology it has “a degenerative effect on the cell membranes because of its protein denaturing properties”.  Other research has indicated that SLS is easily absorbed by the body and enters the blood stream, after which it can enter the kidneys, liver, lungs and brains and accumulate because it stays there for quite a while.


Sodium Laureth Sulfate is SLS´s little brother. SLES is produced by putting SLS through the additional process of ethoxylation to make it more gentle. But during this process the ingredients can become contaminated with 1,4 dioxane. The FDA does not require 1,4-dioxane to be listed as an ingredient on product labels because the chemical is a contaminant produced during manufacturing. The EPA (Environmental Protection Agency) classifies 1,4-dioxane “likely to be carcinogenic to humans”.

Combined with the ingredients DEA (diethanolamine), TEA (triethanolamine) and MEA (monoethanolamine), SLS forms nitrosamines on the skin that are possible carcinogens that are absorbed through the skin. DEA is banned by the European Commission, but can still be found in products in the USA. I read on various websites that all ethanolamines are banned in Europe, but on the list of banned ingredients I could only find DEA.


Sodium Coco Sulfate, or SCS, is similar to SLS, but it is derived from coconuts (although SLS is sometimes too). The difference between the two is that SLS is a relatively simple molecule and has a small molecular mass allowing it to penetrate the skin easily and irritate the underlying living skin cells. SCS has a more complex molecular structure with a greater molecular mass preventing it from penetrating the skin. 

I read websites that say that SCS is just as bad as SLS, like The Natural Penguin, but also ones, like So Organic, saying there is a big difference and that SCS is an alternative that causes less irritation. What do you think?

Summary SLS