EDTA is added to oils and caustic soda during saponification to prevent soaps from becoming mouldy and producing scum.
Ethylenediamine Tetraacetic Acid (EDTA), also called edetic acid, is a white, odourless powder.
It is an anionic chelating agent which means that it can sequester (grab onto) free metal ions or minerals. The analogy we like the most is to describe EDTA like a lobster, with claws closing around the minerals as they float past in the water.
Removing free metal ions and minerals has several benefits. Firstly, it ensures successful saponification. Then, it stabilises formulae by acting as an antioxidant and therefore prevent changes in colour, texture and fragrance. Finally, it reduces the hardness of water, which provides a soft feel to the skin.
Since EDTA and its salts are used in a wide range of cosmetics, food, pharmaceuticals and household cleaning products, they have been the subject of in-depth studies since the 1980s as to their impact on the health and the environment. A regularly raised concern is that they are hardly biodegradable and are therefore found in most water systems. However, according to numerous studies, they aren’t of any problem for the environment or human and animal health as they don't bioaccumulate and are quickly eliminated by organisms. That said, we remain cautious with these materials and avoid overusing them. In 2015, Lush started using a new soap base which helped reduce the amount of EDTA used in our products.