Sodium Lauryl Sulphate (SLS) also known as sodium lauril sulfate or sodium dodecyl sulfate, is a very popular emulsifying, cleaning agent and has become a topic of controversy that some people want it out of their products. You might have heard that it is carcinogenic, toxic to aquatic life, causes endocrine disruption etc.
Where is SLS used?
It is used as a surfactant in personal-care products (toothpastes, soaps, shampoos) and cleaning products (detergents, cleaners). A surfactant is a substance that reduces surface tension and effectively removes dirt from surfaces.
How is SLS derived?
SLS is a synthetic chemical derived from petroleum or plant-based sources like coconut or palm oil.
Is SLS toxic to humans?
There are claims that SLS "absorbs into the bloodstream, bio-accumulates, and causes damage."
Even if any SLS gets absorbed by the skin, most of the material remains in or on the skin surface. Any SLS that is absorbed into the bloodstream is quickly metabolized by the liver into more water-soluble metabolites that are rapidly excreted through the urine, feces, and sometimes expired breath. All hail liver!
SLS alone can be toxic, but it depends on the dosage.
SLS might irritate the skin and / or the eyes (but these products are not designed for ocular use). SLS can produce very gentle products if it is formulated correctly.
Presence of SLS in a product does not mean that it will be less irritating than SLS-free products - it purely depends on how well-formulated the product is.
Is SLS biodegradable?
Research has shown SLS to be highly biodegradable. Degradation is generally reported to be > or = 90% within 24 hours.
Does SLS cause endocrine disruption?
No. There is no evidence for this claim.
Is SLS carcinogenic?
No. There is no evidence to support the idea that SLS causes cancer.
SLS is not listed as a carcinogen by the International Agency for Research on Cancer (IARC); U.S. National Toxicology Program; California Proposition 65 list of carcinogens; U.S. Environmental Protection Agency; and the European Union. In 1998, the American Cancer Society (ACS) published an article attempting to correct the public’s misconception of SLS .
Does SLS harm aquatic life?
Aquatic toxicity refers to the short-term negative impacts to aquatic life from a chemical or finished product, also measured as median lethal dose (LD50). Alone, SLS has an LD50 between 1-13.9 ml/L after 96 hours, making it moderately toxic to aquatic life. This means that while SLS alone is moderately toxic to aquatic life in its raw material form, product formulations that contain dilutions of SLS are not necessarily moderately toxic and, in fact, can be non-toxic to aquatic life.
For example, sodium chloride (table salt) has an LD50 of 3,000 mg/kg, making it moderately toxic by definition.
However, the toxicity of SLS depends largely on the marine species, water hardness, and water temperature. Similar to oral toxicity, this doesn’t mean that formulated products will have this same risk, and in fact, SLS dilutions (or products) are essentially non-toxic to aquatic life under most conditions. Moreover, by the time products reach natural waters, they’re largely degraded. As you remember, SLS is highly biodegradable.
Can I use products with SLS in it?
Whether you choose to use products (personal care and cleaning) with SLS in it is up to you, but now you know that it does not pose any risk if used correctly.
The presence of SLS as an ingredient in cleaning products does not introduce unnecessary risk to consumers or the environment, if properly formulated and qualified, does not pose danger to human health and safety. The perception that SLS is a threat to human health is not scientifically supported, and such claims should be regarded as false and misleading.
Some people may find it drying and irritating on the scalp and choose to opt for SLS-free hair care products, but this may vary from person to person.
Does Scentora use SLS in any of their products?
No, we don't use SLS. We use surfactants like SCI - Sodium Cocoyl Isothionate and SLSa - Sodium Lauryl Sulfoacetate as our primary surfactants. We chose these as they are derived from coconut oil.
1. Human and Environmental Toxicity of Sodium Lauryl Sulfate (SLS): Evidence for Safe Use in Household Cleaning Products: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4651417/
2. Waste-free PhD https://wastefreephd.com/2019/01/23/controversial-chemicals-sodium-lauryl-sulfate-sls/
3. American Cancer Society Debunking the Myth. 1998. [Accessed July 8, 2015]. Available at http://web.archive.org/web/20030803065801/http://www.cancer.org/docroot/nws/content/nws_2_1x_debunking_the_myth.asp.
4. Singer MM, Tjeerdema RS. Fate and effects of the surfactant sodium dodecyl sulfate. Rev Environ Contam Toxicol. 1993;133:95–149.
6. The Eco Well https://www.theecowell.com/blog/sls
Written by Brunda Sreedhar (Co-founder of Scentora)