Know Your Ingredients: Sodium Lauryl Sulfate and Sodium Laureth Sulfate

Sodium lauryl sulfate, which you'll find in many shampoos and toothpastes, makes good bubbles. It is a surfactant, which means it allows the blending of oil-based and water-based liquids. It thickens, allows easier spreading, and lathers up nicely.

It's great for shampoo. And for engine degreasers. It is known to cause skin and eye irritation, and has been, vaguely, linked to canker sores and cancer. The cancer link is regarded as a hoax. Treehugger.com calls it an eco-myth. Other studies have failed to show the same purported correlations.

So is it bad for you?
SLS is a synthetic compound, meaning that it does not occur naturally. Men in white lab coats have to put it together. But it is put together from sulfate and lauric acid, both compounds which do occur naturally. Lauric acid is often obtained from coconut or palm kernel oil.

Tom's of Maine uses it in their toothpaste (except for their SLS-free line).
Dr. Bronner's doesn't use it in personal care products but does use it in SalSuds cleaning product.

SLS can irritate the skin when used in too concentrated an amount. Using coco-betaine and lauryl glucoside in conjunction with the SLS is thought to counter-act the irritant properties (that's what Dr. Bronner's does in their cleaner).
Sodium laureth sulfate (SLES) is closely related to our sodium lauryl sulfate (surprise!). SLES, formed by adding ethylene oxide to SLS, tends to be less irritating to the skin. I've found, however, that many shampoos contain both.

SLS is not the evil bane of natural beauty that it has been purported to be. It may not be the best, most natural option, but it isn't going to make you fall over dead in your shower. It's a man-made combination of two natural compounds. If you use too much, it might hurt you. So don't wash your hair with engine degreaser. I prefer as natural as I can get, so I'll pay more for a shampoo with coco glucoside instead of SLS, but I won't let it bother me if I can't find one.

When you are shopping for beauty product, know what you're paying for. I've noticed some "Natural Shampoos" that contain "saponified oil of coconut." Hmm. Deriviative of coconut oil (lauric acid, anyone?) combined through a chemical reaction with an ester, like sulfuric acid? Sounds strangely familiar...

Image Credits: Ernst Moeksis.