What is SLS (Sodium Lauryl Sulfate)?
Sodium Lauryl Sulfate, or SLS, is a surfactant commonly used in various personal care products. It is inexpensive, easy to make, and foams a lot. However, this ingredient has been the subject of several controversies related to our health and sometimes recognized as particularly harmful. It is accused of being able to cause hair loss, cataracts, and even cancer.
In reality, it is only recognized as an irritant, which is probably why some myths about it are spread.
Indeed, SLS is irritating, and may not be suitable for those with sensitive skin. This is also why it cannot be present at more than 1% in products that are not rinsed off (e.g. a moisturizer). But when used properly and rinsed off afterwards, its irritating potential is drastically reduced. Furthermore, when used in conjunction with other ingredients, SLS can become much less irritating.
The Myth
In many cases, when an ingredient is controversial, there are often two more or less valid sides to the coin. Some studies will show that the ingredient is dangerous, others will not. It often takes knowledge in the field or in research in order to have the necessary tools to navigate everything that is presented and draw fair conclusions. It is often difficult to differentiate between reality and myth, and sometimes, there is not even a clear conclusion to these controversies.
This is not the case with SLS.
The general consensus is that SLS does not cause cancer and the myths surrounding its dangers are entirely false and medically unfounded.
So why is this myth so popular?
Snopes has a particularly detailed overview of this, so I invite you to take a look . But to summarize:
- In 1998, a popular message began to circulate explaining that SLS causes cancer
- SLS is an irritant that is not harmful to the scalp, as it is rinsed off after a few minutes.
- SLS is classified as non-carcinogenic by most government agencies that have a say in the toxicity of an ingredient (in the United States and Canada).
- In the 1970s, a batch of ethanolamine lauryl sulfates was reportedly contaminated with nitrosamines (a substance known to be carcinogenic).
- Snopes' hypothesis is that the author of the original message may have confused these two ingredients (they have a similar name in English) and announced that SLS is carcinogenic.
And there you have it! SLS is not carcinogenic!
Note that it is still an irritant, so avoid eating it or putting it in your eyes. But as mentioned above, it is perfectly safe when used properly.