Question: I have heard some controversial statements concerning the use of sodium lauryl sulfate, or SLS. Can you tell me exactly what SLS is, how it is used, and whether or not I should be concerned?
Laura Seipp responds: The chemical ingredients used in personal care products tend to be surrounded by a fair amount of controversy. There are those on either side of the issue who take an extreme view: “This ingredient is perfectly safe!” to “This ingredient should be avoided at all costs!” Sodium lauryl sulfate, or SLS, is perhaps one of the most controversial of these ingredients in use today.
SLS is a surfactant, degreaser, detergent and emulsifier that is used in thousands of foaming personal care products including shampoo, soap, facial cleansers, body wash, bubble bath, shower gel, shaving cream and toothpaste. Used in strong concentrations, SLS is also used to degrease engines and clean garage floors.
• SLS has been found to penetrate the eyes and tissues. Tests show that SLS can penetrate into the eyes as well as systemic tissues such as the heart, brain and liver, where they are retained for long periods of time.1 This quality makes SLS especially harmful to infants and children.
• SLS can form carcinogenic nitrates when used in shampoos and cleansers containing nitrogen-based ingredients. These nitrates can enter the bloodstream in large numbers and cause eye irritations, skin rashes and allergic reactions.2
• SLS tends to react with DEA (diethanolamine) and TEA (triethanolamine) to form the nitrosamine NDELA, a potent carcinogen that causes the body to absorb nitrates at high levels.3
• SLS strips moisture and oil from the skin and scalp, which may produce inflammation of the skin4, hair damage and hair loss5.
• SLS has been shown in studies performed in Japan to damage DNA in cells.6
Proponents of the use of SLS in personal care products contend that when used in small quantities and in the generally small concentrations found in most personal care products, and when rinsed from the skin or hair immediately and thoroughly, SLS poses absolutely no health risks.
Two common alternatives to SLS that are generally considered to be both mild and safe are ammonium cocoyl isthionate and olefin sulfonate. Sodium laureth sulfate (SLES), closely related to but milder than SLS, has ether added and is therefore considered toxic.7
When choosing personal care products, remember that knowledge is power. Make your choices carefully, and read those ingredient labels!
1 Green, Dr. Keith. “Detergent Penetration Into Young and Adult Eyes.” Department of Ophthalmology, Medical College of Georgia, Augusta, GA
2 Hampton, Aubrey. Dictionary of Cosmetic Ingredients. Organica Press, Tampa, FL
3 Erickson Kim. Drop-Dead Gorgeous. Contemporary Books, New York, NY
4 “Denaturation of Epidermal Keratin by Surface Active Agents.” Journal of Investigative Dermatology, 32-581, 1959
5 Wright, Camille S. Shampoo Report. Images International, Inc. 1989
6 Vance, Judi. Beauty To Die For. toExcel Press, Lincoln, NE