Tuesday, April 26, 2011

The Poisonous Soap (SLES)

Sodium laureth sulfate, or sodium lauryl ether sulfate (SLES), is a detergent and surfactant found in many personal care products (soapsshampoostoothpaste etc.). SLES is an inexpensive and very effective foaming agent.[1]
SLES has been shown to produce eye or skin irritation in experimental animals and in some human test subjects.[2] Some products containing SLES have been found to contain low levels of the carcinogen 1,4-dioxane, with the recommendation from the FDA that these levels be monitored.[3]

Chemical structure

Its chemical formula is CH3(CH2)10CH2(OCH2CH2)nOSO3Na. Sometimes the number represented by n is specified in the name, for example laureth-2 sulfate. The commercial product is heterogeneous in the number of ethoxyl groups, wheren is the mean. It is common for commercial products for n= 3. SLES is prepared by ethoxylation of dodecyl alcohol. The resulting ethoxylate is converted to an half ester of sulfuric acid, which is neutralized by conversion to the sodium salt.[1]The related surfactant sodium lauryl sulfate (also known as sodium dodecyl sulfate or SLS) is produced similarly, but without the ethoxylation step. SLS and ammonium lauryl sulfate (ALS) are commonly used alternatives to SLES in consumer products.[1]


SLES, SLS and ALS are surfactants that are used in many cosmetic products for their cleansing and emulsifying properties. They behave similarly to soap.



Although SLES is considered safe at the concentrations used in cosmetic products, it is an irritant similar to other detergents, with the irritation increasing with concentration.[2] SLES has been shown to produce eye or skin irritation in experimental animals and in some human test subjects.[2] The related surfactant SLS is a known irritant,[4][5] and research suggests that SLES can also cause irritation after extended exposure in some people.[6][7]


Toxicology research by the OSHANTP, and IARC supports the conclusions of the Cosmetic, Toiletry, and Fragrance Association (CTFA) and the American Cancer Society that SLES is not a carcinogen.[8]

[edit]1,4-Dioxane contamination

Some products containing SLES have been found to also contain low levels of 1,4-dioxane, with the recommendation from the U.S. Food and Drug Administration that these levels be monitored.[3] The U.S. Environmental Protection Agencyclassifies 1,4-dioxane to be a probable human carcinogen (having observed an increased incidence of cancer in controlled animal studies, but not in epidemiological studies of workers using the compound), and a known irritant (with a no-observed-adverse-effects level of 400 milligrams per cubic meter) at concentrations significantly higher than those found in commercial products.[9] Under Proposition 65, 1,4-dioxane is classified in the U.S. state of California to cause cancer.[10][11] The FDA encourages manufacturers to remove 1,4-dioxane, though it is not required by federal law.[12]

[edit]See also


  1. a b c Kurt Kosswig,"Surfactants" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, 2005, Weinheim. doi:10.1002/14356007.a25_747
  2. a b c "Final report on the safety assessment of sodium laureth sulfate and ammonium laureth sulfate". Journal of the American College of Toxicology 2 (5): 1–34. 1983. doi:10.3109/10915818309140713.
  3. a b Black RE, Hurley FJ, Havery DC (2001). "Occurrence of 1,4-dioxane in cosmetic raw materials and finished cosmetic products". Journal of AOAC International 84 (3): 666–70. PMID 11417628.
  4. ^ Agner T (1991). "Susceptibility of atopic dermatitis patients to irritant dermatitis caused by sodium lauryl sulphate". Acta Dermato-venereologica 71 (4): 296–300. PMID 1681644.
  5. ^ Nassif A, Chan SC, Storrs FJ, Hanifin JM (November 1994). "Abnormal skin irritancy in atopic dermatitis and in atopy without dermatitis". Archives of Dermatology 130 (11): 1402–7. doi:10.1001/archderm.130.11.1402PMID 7979441.
  6. ^ Magnusson B, Gilje O (1973). "Allergic contact dermatitis from a dish-washing liquid containing lauryl ether sulphate". Acta Dermato-venereologica 53 (2): 136–40. PMID 4120956.
  7. ^ Van Haute N, Dooms-Goossens A (March 1983). "Shampoo dermatitis due to cocobetaine and sodium lauryl ether sulphate". Contact Dermatitis 9 (2): 169. doi:10.1111/j.1600-0536.1983.tb04348.xPMID 6851541.
  8. ^ Rumor: Sodium Lauryl Sulfate Causes Cancer. The Cosmetic, Toiletry, and Fragrance Association. 13, October 2000. Consumer Information
  9. ^ 1,4-Dioxane (1,4-Diethyleneoxide). Hazard Summary. U.S. Environmental Protection Agency. Created in April 1992; Revised in January 2000. Fact Sheet
  10. ^ "1,4-Dioxane cancer 123-91-1 January 1988" (PDF). Office of Environmental Health Hazard Assessment.
  11. ^ "California Files Prop 65 Lawsuit Against Whole Foods, Avalon"Bloomberg.
  12. ^ FDA/CFSAN--Cosmetics Handbook Part 3: Cosmetic Product-Related Regulatory Requirements and Health Hazard Issues. Prohibited Ingredients and other Hazardous Substances: 9. Dioxane

[edit]External links

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