Ask a Chemist: The Truth About Sulphates

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Should consumers be concerned about sulphates in their skincare? Louise Hidinger, PhD chemist, answers our question:

Sulphates, specifically sodium lauryl sulphate (SLS) and sodium laureth sulphate (SLES), are cleansing agents commonly found in skincare and other products, particularly anything foamy. In recent years, these ingredients have gotten a bad reputation. Consumers have become afraid of sulphates as being highly irritating, and there is a continuing urban myth that sulphates may be linked to cancer. SLS and SLES are not carcinogens and have never been linked to cancer.

In the case of sodium laureth sulphate, there is a possibility that it may be contaminated with trace amounts of 1,4-dioxane, a chemical classified as a Group 2B possible carcinogen by the International Agency on Cancer (IARC). To keep that in perspective, examples of other Group 2B possible carcinogens include coffee, Asian pickled vegetables and car exhaust fumes. 

Both sodium lauryl sulphate and sodium laureth sulphate are very effective detergents and will strip oils from the skin, which in turn may cause skin irritation. The issue with SLS and SLES is one of concentration: if these sulphates are present in a product in overly high concentrations, and used too often, the barrier function of the skin can be compromised and irritation may result.

Many consumers associate dense suds with effective cleansing, but they should know that the products that produce a lot of foam also contain relatively high levels of these detergents, which are likely overstripping their skin.

Louise Hidinger is a PhD chemist and the writer behind the website Ingredients: The Science of Beauty.