What is it? Sodium laureth sulphate. Other names it goes by? Sodium lauryl ether sulphate, sodium alkyl ether sulphate, sodium diethylene glycol. What's it used in? Shampoo, body wash, facial cleansers, bubble bath, exfoliants, hair colours and liquid hand soap. What does it do? Helps the product to foam, allowing for smoother distribution. Any controversy? Tests since 1972 have shown it's an irritant for eyes and skin. It may be contaminated with 1,4-dioxane, which the US Environmental Protection Agency says is a probable carcinogen. The US Food and Drug Administration encourages manufacturers to remove 1,4-dioxane, but they are not required to do so under US law.