Photo: The difference between sodium lauryl sulfate (SLS) and sodium laureth sulfate (SLES)?

SLS and SLES are foaming agents. (Credit: Merlinprincesse via Flickr)

SLS and SLES play similar roles in home cleaners and cosmetics. You can often find both of these surfactants or foaming agents in dish soap, liquid laundry detergents, toilet-bowl cleaners, shampoos, bubble bath and facial cleaners. Both can be derived from petroleum, although there are plant-based alternatives as well.

SLS is a skin, eye and respiratory tract irritant that Environment Canada has also categorized as inherently toxic to aquatic organisms, flagging it for further assessment.

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To make SLS less irritating, it is often ethoxylated (by adding ethylene oxide), resulting in the modified compound of SLES. But SLES is also a concern because it can be contaminated with 1,4-dioxane, which may cause cancer (according to the International Agency for Research on Cancer), and it stays in the environment for a long time. Contamination occurs during the process of ethoxylation.

Adria Vasil, author of Ecoholic Home, notes that even some organic dish soaps contain troubling levels of 1,4-dioxane. The good news is that many brands—from Seventh Generation to Whole Food's 365 to Ecover had only trace amounts or have reformulated their products.

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