Why you should avoid SLS & SLES in your cosmetics

What is SLS?

Sodium lauryl sulfate (SLS) and its close relatives sodium laureth sulfate (SLES) and ammonium lauryl sulfate (ALS) are common ingredients in cosmetics. Simply speaking, their role is to make foam and help cleansing your skin and hair. Most likely, all your foamy personal hygiene and household products contain either SLS, SLES or ALS.

    Here are some examples:
    - Shampoo
    - Toothpaste
    - Mouthwash
    - Handwash
    - Facewash
    - Shower gel
    - Bath oil
    - Dishwashing liquid
    - Laundry detergent

    shampoo, ingredients list, sodium laureth sulfate
    A list of ingredients of a typical shampoo

    Anything to worry about?

    1. Skin irritation

    SLS (as well as SLES or ALS) can cause skin irritation. These chemicals remove lipids from the skin 6 and dehydrate it 14. Besides, SLS damages the natural barrier of the skin, allowing other cosmetic chemicals easily penetrate it causing the irritation. Baby skin as well as dry and sensitive skin are especially susceptible to SLS11.

    2. Recurrent aphthous stomatitis (mouth ulcers)

    SLS present in most toothpastes may provoke recurrent aphthous stomatitis - a condition when multiple painful ulcers appear in the mouth 1, 5, 8. Even though the ulcers do not represent any health concern, they do cause significant discomfort. What SLS has to do with this condition? SLS impairs a natural barrier of the mouth 12, 21 and increases exfoliation of the surface cells 8. It makes the mouth skin more vulnerable to infections and various irritating substances 12. Use of SLS-free toothpaste eases the disease: ulcers heal faster and become less painful 21.

    3. Decreasing the efficiency of a toothpaste

    The main positive effect of a toothpaste is a constant delivery of fluoride - an important component protecting teeth from cavities. SLS reacts with fluoride making your toothpaste less efficient and your teeth prone to cavities 2, 3, 13.

    sodium lauryl sulfate, toothpaste, flouride

    4. Contamination of SLES with 1,4-dioxane

    Suprisingly, the main risk of SLES comes not from the chemical itself, but from the way it is produced. SLES often contains trace amounts of carcinogenic substances – ethylene oxide and 1,4-dioxane 9, 10, 18. Both chemicals are banned for use in cosmetics by EU regulations 15, and producers are required to purify SLES from these dangerous components. However, these toxic substances are still found in some cosmetic products 4, 22.

    The problem is that we have no way to know, how much 1,4 dioxane there is in our shampoo or in the toothpaste. Furthermore, other common cosmetic ingredients (e.g. polyoxyethylene lauryl ether, PEG) may also contain similar carcinogenic impurities 7. How much of these carcinogens can we take daily with no risk for our health? The question remains open.

    SLES
    SLES often has traces of 1,4-dioxane, a carcinogenic chemical

    What shall we do?

    Our skin comes into contact with hundreds of chemicals. SLS and SLES are those that your skin will ”meet” many times a day. Avoiding them completely will not be possible as they are present in so many different products. However, you can still reduce the use of SLS-containing cosmetics at home:

    1. Use a SLS-free toothpaste

    2. Choose a SLS-free facewash to prevent skin irritation, especially if you have sensitive skin.

    3. For your baby: choose only SLS-free cosmetics.

    4. Always carefully wash off the product you used – shampoo, shower gel, etc. - since you don't want your skin to stay in contact with SLS/SLES too long.

    5. Watch out for ingredients containing ”-eth”: polyethylene, sodium laureth sulfate, polyoxyethylene because they might contain carcinogenic impurities.

    no SLS, shower gel

    References:

    1. Barkvoll P. Should toothpastes foam? Sodium lauryl sulfate-a toothpaste detergent in focus. Nor Tannlaegeforen Tid. 1989 Feb;99(3):82-4.
    2. Barkvoll P., Rølla G., Lagerlöf F. Effect of sodium lauryl sulfate on the deposition of alkali-soluble fluoride on enamel in vitro. Caries Res. 1988;22(3):139-44.
    3. Barkvoll P. Effect of sodium lauryl sulfate on the uptake of fluoride from NaF and MFP by etched enamel in vitro. J Biol Buccale. 1991 Sep;19(3):235-9.
    4. Black R.E., Hurley F.J., Havery D.C. Occurrence of 1,4-dioxane in cosmetic raw materials and finished cosmetic products. J. AOAC Int. 2001 May-Jun;84(3):666-70.
    5. Chahine L., Sempson N., Wagoner C. The effect of sodium lauryl sulfate on recurrent aphthous ulcers: a clinical study. Compend Contin Educ Dent. 1997 Dec;18(12):1238-40.
    6. Frobe C. L., Simion S. A., Rhein L. D., Cagan R. H., Kligman A. Stratum corneum lipid removal by surfactant: relation to in vivo irritation. Dermatologica 1990: 181: 277–283.
    7. Fruijtier-Pölloth C. Safety assessment on polyethylene glycols (PEGs) and their derivatives as used in cosmetic products. Toxicology. 2005 Oct 15;214(1-2):1-38
    8. Herlofson B.B., Barkvoll P. Oral mucosal desquamation caused by two toothpaste detergents in an experimental model. Eur J Oral Sci. 1996 Feb;104(1):21-6.
    9. International Agency for Research on Cancer (IARC). Re-Evaluation of Some Organic Chemicals, Hydrazine and Hydrogen Peroxide. IARC Monogr. Eval. Carcinog. Risk Chem. Hum. 71, 589–602 (1999).
    10. Kitchin K.T. & Brown J.L. Is 1,4-dioxane a genotoxic carcinogen? Cancer Lett. ,53 67–71 (1990).
    11. Lee C. H., Maibach H. I. The SLS irritation model: an over-view. Contact Dermatitis 1995: 33: 1–7
    12. Linden S.K., Sutton P., Karlsson N.G., Korolik V, McGuckin M.A. Mucins in the mucosal barrier to infection. Mucosal Immunology (2008) 1, 183–197; doi:10.1038/mi.2008.5; published online 5 March 2008.
    13. Melsen B., Rölla G. Reduced clinical effect of monofluorophosphate in the presence of sodium lauryl sulphate. Caries Res. 1983;17(6):549-53.
    14. di Nardo A., Sugino K., Wertz P., Ademola J., Maibach H.I. Sodium lauryl sulfate (SLS) induced irritant contact dermatitis: a correlation study between ceramides and in vivo parameters of irritation. Contact Dermatitis. 1996 Aug; 35(2):86-91.
    15. Regulation (EC) No 1223/2009 of the European Parliament and of the Council of 30 November 2009 on cosmetic products (Text with EEA relevance). Available at: http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=celex:32009R1223. Accessed 2, November, 2015.
    16. Shim Y.J, Choi J.H., Ahn H.J., Kwon J.S. Effect of sodium lauryl sulfate on recurrent aphthous stomatitis: a randomized controlled clinical trial. Oral Dis. 2012 Oct;18(7):655-60. doi: 10.1111/j.1601-0825.2012.01920.x. Epub 2012 Mar 21.
    17. Tahara M., Obama T., Ikarashi Y. Development of analytical method for determination of 1,4-dioxane in cleansing products. Int J Cosmet Sci. 2013 Dec;35(6):575-80. doi: 10.1111/ics.12079. Epub 2013 Aug 5.
    18. U.S. Environmental Protection Agency. Integrated Risk Information System (IRIS) on 1,4-Dioxane. National Center for Environmental Assessment, Office of Research and Development, Washington, DC (1999).