Sodium lauryl sulfate [SLS] and sodium laureth sulfate [SLES] are the lathering agents in soap and shampoo—they make the bubbles. Every few years “natural” soap and shampoo marketers target SLS and SLES as caustic agents to convince potential buyers to switch brands. Their efforts are working as I have recently witnessed my friends with no science background discussing the topic. Because of this, I have watched the videos and read the propaganda written by unqualified authors using bits and pieces of outdated studies that have been taken out of context. It makes me chuckle.
I was first introduced to SLS and SLES bashing in the late 90s when I was taking chemistry courses at UT. One of my professors worked in the soap industry and we had lengthy conversations about chemicals found in soaps, shampoos, and detergents. SLS and SLES are benign lathering agents with no documented general risks or adverse effects. Both have been studied rigorously by independent agencies. Because of the “electric” pull and the size of the molecule, it does not enter the skin and end up “in your system.” This is true for most other ingredients in shampoo as well.
SLS and SLES don’t grow on trees but they are derived from nature. Because the process of doing so occurs in a lab, they are known as chemicals. However, there is a difference between chemicals derived from nature and those constructed by man. Any ingredient with a number in the name is synthetic (manmade) and in large quantities can become a health hazard. 1,4 Dioxane (synthetic chemical carcinogen) and quaternium-15 (a formaldehyde releasing preservative) are ones to watch for.
In addition to synthetic chemicals (again, usually has a number in the name), watch out for “fragrance” on a product’s ingredient list. Under FDA law, a manufacturer does not have to disclose ingredients labeled as “fragrance” to protect against knockoff perfume formulations. Ingredients used to scent shampoos, soaps or detergents are not disclosed to any governing agency and that is where known cancer causing agents may be purposefully hidden.
There are movements in the US to change the “fragrance” protection law but the US Cosmetics, Toiletry and Fragrance Association (CTFA) has strong lobbyists who are paid well by a 60 billion dollar industry. The EU has banned over 1100 chemicals from personal care products because they may cause cancer, birth defects or reproductive problems. The US has banned only 9.
In the meantime, you can protect yourself by avoiding synthetic chemicals and products that contain “fragrance” on the ingredient list. Switching brands frequently might also help to reduce continued exposure to the unlisted ingredients. Alone, the “natural chemicals” in shampoo, such as SLS and SLES, are not going to harm you but the fragrance might.