SLS is a wetting agent, or surfactant, whose purpose is to reduce the surface tension of the water thus allowing the shampoo to spread easier and penetrate the hair more easily. It is a cheap ingredient and mixed with Sodium Stearate, usually composes approximately fifty percent of a shampoos ingredients. About forty percent is water and the other 10 percent is preservatives, fragrance and color. Many shampoos that claim to have herbal extracts usually include them in the water content - which is fine. However, considering all the other chemicals, the risk far outweighs the benefit these herbs provide.
Judi Vance, a pioneer in the fight to educate consumers about the chemicals contained in most personal care products and author of Beauty to Die For has done exhaustive research on SLS. Here are some of the results of her findings:
There are four categories of SLS. They include Anionic, Nonionic, Cationic and Amphoteric. Amphoteric and Anionic are the types found in most shampoos, conditioners and lotions. Anionic are the cheapest and foam the best while Amphoteric are the mildest group and are used in shampoos for their conditioning abilities. Their sibling, the Nonionic group, are used in spray-on oven cleaners. But here is where the problem lies.
A study citied in the Wall Street Journal (November 1, 1988) linked SLS to cataracts and nitrate absorption (nitrates are carcinogens-or cancer causing substances). Apparently, this absorption occurs when the SLS becomes contaminated with NDELA (N-nitrosodiethanolamine) during processing. This contamination comes about as a result of SLS coming into contact with any number of chemicals including TEA (triethanolamine) which is a commonly used ingredient in shampoos as a detergent.
The equation looks like this: SLS + TEA = NDELA (a nitrosamines and a recognized carcinogen).
While many companies claim that SLS itself is a safe ingredient (the jury is still out on this) there is a growing concern with what we refer to as the “chemical cocktail”. When many ingredients come into contact with one another (see the equation above), some will bond forming cancer causing nitrosamines. This is where the danger lies. To be realistic, there is no way that the FDA could possibly test all of the combinations of chemicals available. So, while some chemicals may be mild or classified as safe independently, once you combine them, dangerous things can happen. Just because SLS supposedly comes from coconuts doesn’t mean the molecular structure of the combination of chemicals isn’t potentially damaging.
There is a lot of information available on SLS - it is very controversial these days. At greenfeet, we strongly believe that the presence of the “chemical cocktail” is a very real concern. Be sure to read labels, do your research, don't be afraid to ask questions.