As with most detergents, these Sulfates have an oil-soluble “tail” (seen on the left) and a water-soluble “head” (seen on the right). This gives it a double purpose, it equally loves water and oil which is its main use in personal care products.
When used with copious amounts of water, the Sulfates are fantastic at helping to separate oils from hair and skin – a little too good sadly. Those oils the Sulfates are trying to remove form an important part of your skin barrier, to keep things out and keep the water in.
So what’s the problem with them?
Chemicals by nature are not intelligent, so the detergents cannot distinguish between the unwanted oil we are trying to remove in order to cleanse ourselves and the necessary oils we need to maintain a healthy skin barrier.
To compound the issue, SLS itself is a comparatively simple molecule and therefore quite small in size, giving it the ability to penetrate straight through layers of skin with ease. When SLS penetrates to the deeper layers of the skin, it comes into contact with the delicate cells that are in the process of being formed into the dermis, causing more damage.
What gives SLS its excellent cleaning ability is also it’s biggest concern –
It’s simply too good at its job and is a well-known irritant.
5% SLS in a product is usually enough to cause irritation in most people, but many people are sensitive to far less. SLS is so well-known at being an irritant, it’s commonly used in lab testing to intentionally harm skin: Following application, scientists can test the efficacy of products intended to heal skin.
Although SLS is a potent irritant, there is no scientific evidence to even suggest that it causes cancer, as it’s wrongly claimed by many. (So that’s something positive… I guess?)