The problem with Shampoo (2)

The first post on the "problem with shampoo" (click to read) listed the generic ingredients that go into making shampoo and argued why most ingredients are not really essential and may actually cause more harm than good. This post looks at each of these ingredients in greater detail.

Surfactants/Detergent: Shampoos work by employing detergents that are both lipophilic (fat-loving) and hydrophilic (water-loving). The lipophilic action helps in attaching to sebum (natural oil secreted by the skin/scalp) and the hydrophilic action helps removal of this sebum when hair is washed/rinsed with water. Typically shampoos contain combinations of different detergents to achieve desired results: very oily hair = strong detergent; dry hair = mild detergent and so on. Based on polarity and chemical ionic properties, shampoo detergents can be further classified but that would be too technical and beyond the scope of this post and hence not discussed. Examples of a few detergents/surfactants used in shampoos include:

• Lauryl Sulfates: Usually listed as a second or third ingredient on the label, under the names sodium lauryl sulfate (SLS), triethanolamine lauryl sulfate, and ammonium lauryl sulfate (ALS).
• Laureth Sulfates: One of the most common primary detergents in shampoo designed for normal-to-dry hair and popular with consumers because they produce luxuriant foam. They would be listed under the names sodium laureth sulfate (SLES), triethanolamine laureth sulfate, and ammonium laureth sulfate.

Pick up any popular shampoo brand and it will usually contain either Lauryl or Laureth Sulphate as an active ingredient. A few exclusive shampoos have entered the market that claim to be "SLS-free".

• Sarcosines: Not usually used as primary detergents as they are poor cleansers but excellent conditioners and therefore are often added to shampoos that offer the "added benefits of conditioning" - the bounce, the shine and all the bells and whistles that we fall for. These detergents would be listed as lauryl sarcosine and sodium lauryl sarcosinate.
• Sulfosuccinates: Very strong detergents that are usually present in shampoos for very oily hair and listed as disodium oleamine sulfosuccinate and sodium dioctyl sulfosuccinate.
• Other detergents: Include polyoxyethylene fatty alcohols, polyoxyethylene sorbitol esters and alkanolamides which are milder and usually feature as secondary detergents. Some ingredients like cocamidopropyl betaine and sodium lauraminopropionate are found in baby shampoos because they are non-irritating to the eyes or so goes the claim but if the truth of the pudding is in the eating, then allow it to run into a baby's eyes and the truth will emerge.

A recent trend is the return of "Natural Cleansers" derived from plant sources such as Sarasparilla, soapwort, ivy agave etc. which are called "natural saponins" - They have excellent foaming properties but are poor cleansers and work only when used in very high concentrations. Marketers get over this problem by combining these with synthetic detergents listed above - The synthetic detergents do all the cleansing while the "natural detergents" do the marketing and selling - "Herbal, Natural, Ayurvedic etc. etc.

Although detergents such as SLS, SLES have not yet been classified as carcinogenic (cancer-causing) there have been persistent and troubling reports from various studies that point to how these detergents and several others used in shampoos, toothpastes, soaps are serious and often dangerous irritants. The International Journal of Trichology recommends that these detergents should not be used in concentrations above 1%. The full article can be read here. At higher concentrations, SLS can be a very harmful irritant. At a concentration of 10% it caused serious corneal / eye damage in rabbits. One other concern with SLS is the risk of contamination with 1,4 Dioxane a confirmed carcinogen when it is extracted through a process called ethoxylation (the suffix "Eth" in SLS comes from this process of ethoxylation). Then again, the question that needs to be asked is why is a detergent that is also used as an industrial cleanser present in cosmetic and personal care products?

There is a lot more that can be said and a lot, lot more that should cause concern but that should be the topic of another post that will look at the other ingredients that make up shampoo formulations and the associated concerns, risks, and issues.

References:

1. http://journals.sagepub.com/doi/abs/10.3109/10915818309142005
2. https://www.forbes.com/sites/quora/2016/03/16/is-common-shampoo-ingredient-sodium-laureth-sulfate-harmful/#63932b6b7543
3. http://articles.mercola.com/sites/articles/archive/2010/07/13/sodium-lauryl-sulfate.aspx