Cleansing and foaming
Sodium lauryl sulfate creates a rich foam and cleanses the hair and skin. Its thorough action dissolves dirt and grease effectively.
Sodium lauryl sulfate is a surfactant. All surfactants are partly water-soluble and partly oil-soluble, allowing oil and water to become dispersed. Above a minimum concentration, the surfactant molecules become organised in a structure that can trap the oil based dirt from the hair, allowing it to be rinsed away. Sodium lauryl sulfate gives thick, rich foam which helps the hands to work the shampoo through the hair while it’s thorough cleansing action dissolves dirt and grease effectively.
Sulfates became widely used in the 1930s and they started the development of the modern shampoo industry. Sodium lauryl sulfate has been used for more than sixty years as a main shampoo ingredient. It is now being superseded by milder surfactants.
Surfactants cleanse the hair leaving the hair fresh, clean and with great shine. Soap (which is one of the oldest surfactants) will clean the hair but its alkalinity tends to cause roughening of the cuticles on the hair follicle, leading to a dull appearance.
Should you be stressed about SLS?
In recent years, there has been increased negativity towards products that contain SLS, partly because reports have incorrectly linked it to cancer. Nicola Smith, health information officer at Cancer Research UK, told us: “There’s no evidence to suggest that sodium lauryl sulphate causes cancer. Cosmetics are under tight regulation in Europe and have to be shown to be safe before they can be sold. Unfortunately, there are a lot of unfounded rumours on the internet about cosmetics causing cancer but they simply aren’t backed up by convincing scientific evidence.”
It’s likely that these concerns stem from confusion surrounding the manufacturing process. The SLS that we use is derived from coconut and/or palm kernel oil, both of which are rich sources of lauric acid. This lauric acid is processed into SLS by adding sulphuric acid (from petroleum) followed by neutralisation with sodium carbonate (a natural mineral). Some reports have claimed that this process produces chemical compounds known as ‘nitrosamines’, of which 90% are believed to be carcinogenic. However, it’s chemically impossible for nitrosamines to be found in SLS.
“For years, sodium lauryl sulfate has been developing a negative reputation with consumers due to flawed interpretations of the scientific literature that continue to be perpetuated,” says Cosmetic Chemist Kelly Dobos. “Sodium lauryl sulfate is produced by the sulfation of lauryl alcohol. No chemicals used in the synthesis contain nitrogen so the resulting SLS contains no nitrogen and therefore no possible presence of nitrosamines.”
There are also concerns about the impact that SLS can have on marine life, since all soap and shampoo products are released into the environment via household water waste. According to Kelly, we don’t need to worry. She explains: “The ability of a chemical to decompose into simple, nontoxic components under normal environmental conditions within a short period of time (96 hours or less) means that it is biodegradable. SLS has been shown to be readily biodegradable not biopersistant. By the time personal care product ingredients reach natural waters, they are mostly degraded. Ecotoxicity studies have determined that these low concentrations of SLS would be essentially nontoxic to fish and other aquatic life.”
Getting in a lather
Many of us don’t feel completely clean unless we use lather up with soaps and shampoos. However, the sulphates which are responsible for producing this luxurious foam can be harsh and drying, leaving hair frizzy. Although dryness is a common concern, irritation is unlikely, even among people who have sensitive skin, provided that the foam is rinsed off thoroughly. In fact, the risk is so small that there are no EU limits on the usage of SLS in wash-off products, as irritation only occurs with products that are left on the skin.
“Most people can use products containing SLS without worrying about skin or scalp irritation,” says Dr Stefanie Morris, Dermatologist & Medical Director at European Dermatology London. “This is because it’s a rinse-off product — the contact time is short and, after rinse-off, there is extremely little SLS (if any), which stays on the skin/scalp.”
If your hair is dry, delicate, damaged or processed, you’ll be happy to hear that the majority of Lush liquid shampoos are SLS-free, and contain the gentler surfactants ammonium laureth sulphate (ALS) and sodium alkyl sulphate (SAS) instead. For example, Curly Wurly shampoo contains ALS along with coconut and jojoba oil to nourish curly hair, while Blousey shampoo contains ALS along with bananas, cocoa and cupuaçu butters to soften hair and restore moisture.
Alternatively, shampoo bars are an excellent option for sensitive scalps, mainly because of the way they are used. A single shampoo bar is the equivalent to three 200ml bottles of liquid shampoo, so although they contain a very high concentration of SLS — up to 90% — the risk of irritation is very low because only the foam is applied to the hair and scalp. We recommend shampoo bars to customers who want to reduce their SLS usage because the amount that you apply is easier to control. There’s no need to squeeze a large dollop of shampoo onto your scalp. Instead, you prepare the product in your hands first, before distributing it evenly through the hair.
“This is quite a dramatic difference,” explains Lush co-founder and herbal trichologist Mark Constantine. “When you use a liquid shampoo you apply the neat material to your scalp, but you don’t get that with a shampoo bar — you only get the foam that comes off the material, which means that even people with the most sensitive scalps can use it.”
If you’re sold on shampoo bars but want a lower-SLS alternative, try Jason And The Argan Oil shampoo bar; it’s made with agar agar, a cleansing seaweed extract, which enables us to use 23% less SLS.
Raising the bar
In 2017, we launched our reformulated gourmet soap range using our own in-house soap base. Our base has been palm free since 2006, but now that we don’t need to add SLS or sodium stearate we can guarantee that the entire soap, and all its ingredients, don’t include any traces of palm.
This in-house soap base is made from a blend of Fair Trade organic cocoa butter, extra virgin coconut oil and organic castor oil, mixed with sodium hydroxide to induce a reaction called saponification. This creates the lathering solid base of the soap on which infusions, juices or oils are added to benefit the skin and provide fragrance. It can also be blended with other soap bases made with different ingredients such as olive or argan oil, to create a greater range of textures and lathers.
We’ve since reformulated some of our most popular soaps too, including Honey I Washed the Kids, Coalface and Rock Star. These are currently only available on our website and, as a result, the majority of our soaps no longer contain SLS.
What this is all means is that customers now have even more choice, making it easier to find the products and ingredients that work best for you.