What does Sodium Lauryl Sulphate do to Your Skin?
The ‘surfactant’ is the part of a soap or detergent mixture that does the actual dirt and oil removal (the cleaning). The most common surfactants that you will find added to soaps and shampoos as well as many detergents are the Linear Alkyl Sodium Sulfonates (LAS). These surfactants include the well known surfactant, sodium lauryl sulfate. It may surprise you to hear that skin contact with these surfactants can give rise to skin irritation and damage. But, this is a well known fact among those that test surfactants and other personal use chemicals. Skin irritation and damage will occur if your skin comes in contact with this surfactant for long enough. This is due to the effect the surfactant has upon the structure of the membranes of your skin.
Basically, a surfactant such as sodium lauryl sulfate affects your skin by partially dissolving the cell membranes of your skin cells. This anionic surfactant is also able to penetrate right into living cells. Cell membranes are made up primarily of lipid (another name for fat) molecules. The molecules of the lipids which compose the membrane of cells are very similar in nature to anionic surfactant molecules. And, it is therefore not surprising that some surfactants are very readily absorbed into the skin cell membranes. Sodium lauryl sulfate is one of the most readily absorbed surfactants, in fact, and it has been chosen for experimental purpose to enhance the penetration of different elements in living systems.
The damage taking place to your skin when you use this surfactant is not noticeable to you at first. Only at sufficiently high concentrations of sodium lauryl sulfate on your skin will you detect the damage that it is causing. At lower concentrations, you will still suffer cellular damage; you just will not be able to tell it is happening.
In an experiment comparing different skin irritants including hydrochloric acid, DMAC and others sodium lauryl sulfate showed a most significant effect on skin mitotic activity (cell division rate). This is to say, that with applications of between 0.5% sodium lauryl sulfate and 2% sodium lauryl sulfate increased cell division rates up to twenty five fold. Skin cells respond in this way when they suffer damage. Not only this, but, at levels of 2% sodium lauryl sulfate the solution was sufficiently toxic to prevent cells from dividing at all and perhaps destroying them.
In other experiments sodium lauryl sulfate was was shown to specifically remove ceramides and cholesterol from the skin. These compounds are responsible for the barrier function of skin. Other studies have shown that proteins are removed from skin that is being rinse with sodium lauryl sulfate solutions. This means that the protein component of your skin’s surface is in actually, in part, being de-natured and washed away when you wash your body with a cleanser which contains the surfactant sodium lauryl sulfate.
Sodium Lauryl Sulfate from Natural Sources is not Necessarily Safe
Besides the direct harm that Linear alyl sodium sulfonates can cause to the surface of your skin other risks are associated with the use of these substances. As with many synthetic compounds, these surfactants will carry with them minute amounts of trace impurities. Sodium lauryl sulfate can be produced from palm oil, it is know as the coconut surfactant. Because of this sodium lauryl sulfate is often regarded as a safe, natural source surfactant. Unfortunately, though it is derived from plant sources, it can not be expected to be toxin free.
The manufacturing processes used to create sodium lauryl sulfate are still subject to tainting with dioxins even when they are produced from plant sources. Benzenes may also be present as impurities. These toxins are carcinogenic and are harmful to the unborn. Not only are they harmful to the person who uses the detergent that accidentally contains them, but, they are frequently leaked into the environment during the manufacturing of the surfactant. Outbreaks of dermatitis, in Scandinavia, on a couple of occasions, were traced to impurities which were present in particular improperly processed batches of sodium lauryl sulfate used to produce detergent with.
Is the coconut surfactant really safe and natural? It does not look like it is. Check the labels of your personal care products. It is surprising how many products are formulated with this surfactant. Personally I would consider purchasing different and more simple products in the future. Natural soaps made with old fashioned saponified fats (the same as bar soap) would be my first pick.
Gloxhuber, C., Klaus Kunster; Anionic Surfactants: Biochemistry, toxicology, dermatology, Surfactant Science Series, Volume 43, second edition, revised and expanded. New York, USA, 1992. pages 299 – 302,
This post is part of the series: All About Surfactants in Laundry Detergents
- Green Laundry Detergents and the Chemical Structure of Surfactants
- Are the Cleaning Compounds (The Surfactants) in Laundry Detergents Really Safe to Use?
- More Synthetic Surfactants: Fabric Softeners and Other Questionable Inventions
- The Case of Nonionic Surfactants in Europe and America: To Ban or Not to Ban
- Is Sodium Lauryl Sulfate a Natural Surfactant?