Sodium Lauryl Sulfate (SLS)

Sodium Lauryl Sulfate (SLS), also known as Sodium dodecyl sulfate, is a widely used surfactant in cleaning products, cosmetics, and personal care products. The sodium lauryl sulfate formula is a highly effective anionic surfactant used to remove oily stains and residues. It is found in high concentrations in industrial products, including engine degreasers, floor cleaners, and car wash products, where workplace protections can be implemented to avoid unsafe exposures. SLS is also used in lower concentrations in household and personal care products such as cleaning products, toothpastes, shampoos, and shaving foams.

SLS has been thoroughly reviewed for its safety by a number of governments. For example:

• Based on a thorough safety review, including consideration of chronic risks, the U.S. Environmental Protection Agency (EPA) has issued an exemption for SLS from the requirement of tolerance for residues when used as a component of food contact sanitizing solutions applied to all food contact surfaces in public eating places, dairy-processing equipment, and food-processing equipment and utensils at a maximum level in the end-use concentration of 350 parts per million (ppm). The regulation eliminates the need to establish a maximum permissible level for residues of sodium lauryl sulfate. http://www.epa.gov/fedrgstr/EPA-PEST/2009/August/Day-12/p19314.htm

• The Food and Drug Administration (FDA) includes Sodium Lauryl Sulfate on its list of multipurpose additives allowed to be directly added to food. Sodium Lauryl Sulfate and Ammonium Lauryl Sulfate are also approved indirect food additives. For example, both ingredients are permitted to be used as components of coatings.
  
  Links to the Code of Federal Regulations related to FDA evaluations for Sodium Lauryl Sulfate and Ammonium Lauryl Sulfate are:
   
  • http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=172.822&SearchTerm=sodium%20lauryl%20sulfate
  • http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=175.320&SearchTerm=sodium%20lauryl%20sulfate
     
  • http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=175.210&SearchTerm=ammonium%20lauryl%20sulfate
• Sodium Lauryl Sulfate and Ammonium Lauryl Sulfate may be used in cosmetics and personal care products marketed in Europe according to the general provisions of the Cosmetics Directive of the European Union.
  
  Link to the EU Cosmetics Directive: http://ec.europa.eu/commission/index_en

• The Organization of Economic Cooperation and Development, which is an organization of 30-plus developed countries, has reviewed the human and environmental hazards of a category of chemicals that includes Sodium Lauryl Sulfate. No chronic human health hazards, including carcinogenicity, were identified.
  
  The hazard assessment for the category (alkyl sulphates, alkane sulphonates and alpha-olefin sulphonates category) is posted on the OECD website.

SLS has also been thoroughly reviewed for human safety by an industry funded, independent panel, which found:

• There is no evidence of harm from the use of SLS in cosmetic products, where there is intentional, direct contact with the skin. The ingredient was reviewed in 1983 and re-reviewed in 2005 by the Cosmetic Ingredient Review (CIR)1 Expert Panel and found to be safe for use in cosmetic and personal care products. SLS can cause skin irritation in some persons, which is one reason why it is important to follow the label instructions when using a cleaning product. A complete report on SLS is available from CIR.

SLS functions in cleaning product as a surfactant, wetting surfaces, emulsifying or solubilizing oils, and suspending soil so that they can be rinsed away. This ingredient contributes foaming properties to cleaning products.

SLS is safe for use in cleaning products.  It has been through numerous reviews. There is no direct or circumstantial evidence that this ingredient has any carcinogenic potential. The studies that have been conducted on SLS indicate it is safe under proper conditions of use. Workplace exposures to SLS could be expected to be significantly higher than in the consumer use setting due to either the higher use concentrations and/or longer duration of use that can occur in the workplace. Since the primary side-effect of SLS, namely skin irritation, is dependent on the level and duration of exposure, consumer product formulators design products to avoid or minimize this effect during consumer use.

SLS is not listed by any authoritative bodies as a carcinogen, including the International Agency for the Research of Cancer (IARC), U.S. National Toxicology Program (NTP), California's Proposition 65 list of carcinogens, U.S. EPA or the European Union.

For several years there has been misinformation circulating on the Internet about Sodium Lauryl Sulfate, falsely labelling SLS as a carcinogen. This allegation is unsubstantiated and false.

Find out more about this Internet myth:

• The Personal Care Products Council has commented on the Internet rumors in the context of SLS in cosmetics and personal care products.
  • http://www.cosmeticsinfo.org/HBI/20
  •  BACKGROUND: SLS Use in Cleaning Products
• Urban Legends: http://urbanlegends.about.com/library/weekly/aa090998.htm​​​​​​
• Snopes.com: http://www.snopes.com/inboxer/household/shampoo.asp
• American Cancer Society: http://www.cancer.org
• Personal Care Products Council: http://www.cosmeticsinfo.org/HBI/20

CIR¹ Safety Review: The safety of Sodium Lauryl Sulfate, and Ammonium Lauryl Sulfate, has been assessed by the Cosmetic Ingredient Review (CIR) Expert Panel. The CIR Expert Panel evaluated scientific data and concluded that Sodium Lauryl Sulfate and Ammonium Lauryl Sulfate were safe in formulations designed for discontinuous, brief use, followed by thorough rinsing from the surface of the skin. In 2002, the CIR Expert Panel considered available new data on Sodium Lauryl Sulfate and Ammonium Lauryl Sulfate and reaffirmed this conclusion. Sodium Lauryl Sulfate can be  an irritant at concentrations of 2% or greater. Irritation increases with the concentration of the ingredient. The longer this ingredient stays in contact with the skin, the greater the likelihood of irritation, which may or may not be evident to the user.

The CIR Expert Panel also found that, although Sodium Lauryl Sulfate is not carcinogenic, it has been shown to causes severe epidermal changes to the area of skin to which it was applied. Other studies found heavy deposition of the detergent on the skin surface and in the hair follicles; damage to the hair follicle could result from such deposition. Further, it has been reported that 1% and 5% Sodium Lauryl Sulfate produced significant number of comedones. These two problems—possible hair loss and comedone formation—along with proven irritancy, should be considered in the formulation of cosmetic products containing these ingredients.

Resources

Sodium Lauryl Sulfate is used in cosmetics and personal care products marketed in the U.S. Link to Personal Care Products Council web pages on SLS: http://www.cosmeticsinfo.org/ingredient_details.php?ingredient_id=178

Wikipedia page on Sodium Lauryl Sulfate: http://en.wikipedia.org/wiki/Sodium_lauryl_sulfate

National Library of Medicine website:
http://hpd.nlm.nih.gov/cgi-bin/household/brands?tbl=chem&id=204

Footnotes:

¹CIR was established in 1976 by CTFA (Cosmetic, Toiletry, and Fragrance Association, now the Personal Care Products Council). CIR is a unique endeavor to assess the safety of ingredients used in cosmetics in an unbiased, expert manner. Its findings have established a public record of the safety of cosmetic ingredients. The heart of the CIR program is the Independent Expert panel consisting of world-renowned physicians and scientists. Expert Panel members must be free of any conflicts of interest, and must meet the same conflict of interest requirements as outside experts to the Food and Drug Administration (FDA).

In addition to the seven Expert Panel voting members, FDA and the Consumer Federation of American, and CTFA provide liaison members to the panel. Although funded by CTFA, CIR and the review process are distinctly separate and independent from CTFA and the cosmetic industry. CIR is located at 1101 17th Street NW, Suite 310, Washington, DC 20036, www.cir-safety.org.