Sodium Laureth Sulfate is a member of a group of fatty alcohol sulphates (Sodium Lauryl Sulfate, Magnesium Lauryl Sulphate, TEA Lauryl Sulphate, etc…). This group of "surfactants" comprise the most widely used range of foaming and cleansing agents for shampoos, bubble baths, shower gels, hand cleansers, etc., in North America. In fact, more than 80% of all major brand shampoos contain at least one of the Lauryl Sulfates or Laureth Sulfates. Laureth Sulphates (like Sodium Laureth Sulfate) are simply Lauryl Sulfates that have been ethoxylated (treated with ethylene oxide) to make them more gentle on the skin. After the ethoxylation process, the ethylene oxide is also removed from the Sodium Laureth Sulfate, leaving us with a safe, gentle cleansing agent.
A number of years ago, in 1983, Sodium Laureth Sulfate received some bad publicity because small amounts of dioxin (a toxic and carcinogenic compound) were found in some batches of the raw material. Since then, the better suppliers of Sodium Luareth Sulfate have improved their production techniques to a point where dioxin levels are no longer an issue. The SLEs used in the Harper formulas is highly purified and dioxin free.
As to irritation - irritation studies are done on the skin with an "occlusive" patch test. This means that the SLS is applied to the skin, and then it is sealed with a special patch so that the compound cannot be washed off for 24 to 72 hours. Under these conditions, more than 90% of all cosmetic compounds will cause skin irritation to some degree.
Keep in mind that SLS is used primarily in wash-off products such as shampoos and some skin cleansers. SLS is not a substantive compound, which means that it does not remain on the skin or hair if proper rinsing is done, so the exposure time on the skin is usually less than 60 seconds. High concentrations (above 10%) certainly can be irritating if the SLS is not modified with other desensitizing compounds - like the amphoterics. A typical Baby Shampoo does contain about 7% SLS, but it also contains ingredients such as Sodium Amphoglycinate to give a product that is not only non-irritating but non-stinging to the eyes as well. It must be pointed out again; concentration means everything to irritation potential.
The Harper shampoos contain SLES (Sodium Laureth Sulfate). Through the ethoxylation process this is a different ingredient than SLS and should not be confused with SL. We have combined Sodium Laureth Sulfate with a corn oil derived foaming agent (Decyl Polyglucose) and Cocamidopropyl Betain, a coconut based amphoteric compound - widely used for its exceptional ability to form a complex with SLES to make it very mild on the skin and hair. In addition, other compounds such as Wheat Proteins and Chamomile are used to make the overall product very gentle on all types of skin.. This unique combination produces a cleanser with improved conditioning qualities and a greatly reduced potential for skin irritation. The Harper formulas have been further enhanced through the use of special vegetable proteins and carefully selected botanicals to produce products with outstanding overall qualities - better cleansing, improved conditioning, easier comb-out, repair of damaged hair, etc.