EDTA is in many products as a preservative, to stabilize it, or to enhance the foaming action. It’s also used as a chelating agent, which means it us used to precipitate out metals from the formulation (if tap water were used to make the formulation instead purified water, for example, and it can bind with metals dissolved in your shower water).
Why is it harmful for you?
Tetrasodium ETDA is made from ethylenediamine, formaldehyde—a known carcinogen according to the National Cancer Institute—and sodium cyanide (which is made from the toxic gas hydrogen cyanide). Even though, it has been scientifically not proven that EDTA itself is carcinogenic, it is better to be on the safe side of this ingredient.
EDTA is also a penetration enhancer. That means it breaks down the skin’s protective barrier, making it easier for other potentially harmful ingredients in the formula to sink deeper into your tissues.
Why is it harmful for the environment?
A study conducted in 2003 brings EDTA use under scrutiny. The compound has one of the highest concentrations in inland European waters. In natural environments studies detect poor biodegradability. It is concluded that EDTA behaves as a persistent substance in the environment and that its contribution to heavy metals bioavailability and remobilization processes in the environment is a major concern.