Have you ever drank orange juice after you brushed your teeth and it strangely tastes terrible? This is because of a chemical compound called sodium lauryl sulfate— one of the ingredients in many toothpaste brands (BBC Science Focus, n.d.). Sodium lauryl sulfate, or SLS for short, acts as the foaming agent in toothpaste. When you brush your teeth, this chemical coats the inner lining of your mouth and as a result, the SLS impairs the tastebuds on your tongue making the orange juice taste bitter rather than sweet!
You’re probably wondering what SLS is and what its other purposes are since it surely can’t only be in toothpaste. First and foremost, SLS is naturally derived from coconut, palm, and petroleum oil but can also be man-made in labs (Bondi et al. 2015). SLS appears white or off-white in color and typically has a faint odor of fatty substances. It comes in many forms such as crystals, flakes, powders, and sometimes even in liquid form. The chemical formula for sodium lauryl sulfate is C12H25NaSO4 meaning that it is an organic compound with a 12-carbon long chain and a sulfate group attached to the end of it (National Center for Biotechnology Information, 2023). Because of its chemical structure, SLS has amphiphilic properties making it a surfactant (American Cleaning Institute, 2022). This means that it has both a non-polar, hydrophobic (water-hating) tail and a polar, hydrophilic (water-loving) head. In this case, the carbon chain acts as the hydrophobic tail and the sulfate group is the hydrophilic head. A surfactant works by lowering the surface tension between two materials, typically water and oil, dirt, or grease. Hence, SLS is not only found in toothpaste but several other personal care products and cleaning products. For instance, if you were to look at the ingredients list of products such as shampoo bottles, dish soaps, and detergents, there is a high chance that you will find sodium lauryl sulfate listed there (Schaefer, 2019). SLS is practically what creates the suds in many of these items. Among its purposes of being a foaming and lathering agent, SLS also acts as a wetting agent, thickening agent, and emulsifier. Because it is so versatile, SLS is not only found in cleaning and personal care products but is also used as a food additive. SLS is often added to foods such as marshmallows or dried egg products to help emulsify the ingredients (FooDB, 2018).
Since it is such a common ingredient in many products, you’re probably wondering whether SLS is safe to use or consume on a daily basis. The concentration of SLS found in consumer products varies by product and manufacturer but typically ranges from 1% to 30% in cleaning products and 0.01% to 50% in cosmetic products (Bondi et al. 2015). Generally, SLS is safe in products that are meant to be rinsed off such as shampoos, conditioners, body washes, dish soaps, and detergents. If you do end up ingesting it or getting it into your eyes, it is best to try not to induce vomiting, drink a glass of water, and ensure that you rinse your eyes thoroughly (Eisenbraun, n.d.). However, it is recommended that if you happen to be someone who has sensitive skin or possibly has a specific skin condition such as acne, eczema, or skin psoriasis, it may be best to avoid products with SLS overall. If your skin is sensitive to SLS, the area would become red, dry, scaly, itchy, or sore (U.S. Coast Guard, 1999). If you are looking for some safer alternatives, I would suggest going to SkinSAFEproducts.com as it is a helpful website that offers users a list of various products that can filter out potentially harmful ingredients (SkinSAFE, 2023). Ultimately, if you think that SLS may be the reason why certain products are causing adverse skin reactions, I would definitely try out SLS-free products!
Exam questions:
Why does SLS have amphiphilic properties?
What are three different purposes as to why SLS is added to products and/or food?
What are a few indicators that you may be sensitive to SLS?
References
American Cleaning Institute. (2022). Sodium Lauryl Sulfate (SLS). https://www.cleaninginstitute.org/industry-priorities/policy/other-issues/sodium-lauryl-sulfate-sls
BBC Science Focus. (n.d.). Why does toothpaste make everything taste horrible? BBC Science Focus. https://www.sciencefocus.com/the-human-body/why-does -toothpaste-make-everything-taste-horrible/
Bondi, C. A., Marks, J. L., Wroblewski, L. B., Raatikainen, H. S., Lenox, S. R., & Gebhardt, K. E. (2015). Human and Environmental Toxicity of Sodium Lauryl Sulfate (SLS): Evidence for Safe Use in Household Cleaning Products. Environmental health insights, 9, 27–32.
Eisenbraun, K. (n.d.). Dangers of sodium lauryl sulfate. Livestrong. https://www.livestrong.com/article/174367-dangers-of-sodium-lauryl-sulfate/
FooDB. (2018). Sodium Lauryl Sulfate.https://foodb.ca/compounds/FDB020359
National Center for Biotechnology Information (2023). PubChem Compound Summary for CID 3423265, Sodium dodecyl sulfate. https://pubchem.ncbi.nlm.nih.gov/compound/Sodium-dodecyl-sulfate
Schaefer, A. (2019). What is Sodium Lauryl Sulfate (SLS)? Healthline weblog.
https://www.healthline.com/health/beauty-skin-care/what-is-sodium-lauryl-sulfate
SkinSAFE. (2023). SkinSAFE products. https://www.skinsafeproducts.com/
U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. https://hero.epa.gov/hero/index.cfm/reference/details/reference_id/5208492
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