SODIUM LAURETH SULFATE (SLES)
Chemical name: Sodium Lauryl "ether" Sulfate. An ether chain is added to SLS, and is called a premium agent in cleansers and shampoos. In reality it is very inexpensive, but thickens when Sodium Chloride (salt-NaCl) is added in the formula and products high levels of foam to give the concentrated illusion it is thick, rich, and expensive. Used as a wetting agent in the textile industry, SLES is irritating to scalp and may cause hair loss (Wright).

SODIUM LAURYL SULFATE (SLS)
Sodium Lauryl Sulfate is an anionic detergent. It is used all over the world. SLS is the universal standard used to irritate skin in clinical testing so medical researchers can test ingredients to see how fast the skin heals.

It is commonly found in liquid soaps and shampoos, bubble baths, bath and shower gels, and in most all toothpastes marketed throughout the world. SLS has showed penetration into the eyes, as well as systemic tissues (brain, heart, liver, etc.). SLS also showed long-term retention in tissues. Because SLS and related substances are widely used in many populations on a daily basis in soaps and shampoos, there is an immediate concern relating to the penetration of these chemicals into the eyes and other tissues. This is especially important in infants, where considerable growth is occurring, because a much greater uptake occurs by tissues of younger eyes, and SLS changes the amounts of some proteins in cells from eye tissues. Tissues of young eyes may be more susceptible to alternation by SLS (Green).

SLS forms nitrates, possible carcinogens, when used in shampoos and cleansers containing nitrogen based ingredients. These nitrates can enter the blood stream in large numbers from shampooing, bubble baths, bath, and shower gels and facial cleansers. These synthetic substances are used in shampoos for their detergent and foam-building abilities. They can cause eye irritations, skin rashes, hair loss, scalp scurf similar to dandruff, and allergic reactions.

Dr. David H. Fine, the chemist who uncovered NDELA contamination in cosmetics, estimates that a person would be applying 50 to 100 micrograms of nitrosamine to the skin each time he or she used a nitrosamine-contaminated cosmetic. By comparison, a person consuming sodium nitrite-preserved bacon is exposed to less than 1 microgram of nitrosamine (Hampton).

Green, Dr. Keith -

"Detergent Penetration into Young and Adult Eyes"
Dept. Of Opthalmology, Medical College of GA Augusta, GA