EDTA
The chelating agent named on the label by its own initials, because its persistence in the environment made it worth naming.
In detail
EDTA is a chelating agent: a molecule that wraps around a metal ion and holds it in a cage of its own bonds, so the ion can no longer react with anything else. It is very good at this across a wide range of metals, which is why it appears in cleaning products, in food, in cosmetics and in medicine. In a cleaner its jobs are the familiar ones — soften the water so surfactants are not precipitated, hold back the trace metals that would decompose a peroxide bleach, and lift metal-containing stains such as rust that are held to a surface by an ion rather than by a film. It is one of only two chelating agents the detergent labelling law names individually rather than by class, alongside NTA. That reflects concern about how poorly it degrades in the environment and how effectively it can remobilise metals already settled in sediment.
Why
Sources for this page
Sources
Regulation (EC) No 648/2004 on detergents, Annex VII — labelling and ingredient data sheet
European Parliament and Council, as retained in UK law (legislation.gov.uk), 2004 · Government or regulator
Relied on for: That EDTA and its salts are named individually in the detergent labelling annex and declared in weight bands above 0.2%. (states this directly)
Safer Chemical Ingredients List — functional-use classes
United States Environmental Protection Agency (EPA), Safer Choice · Government or regulator
Relied on for: That the class is one of the functional-use classes a cleaning formulation is assessed in. (states this directly)
Kirk-Othmer Encyclopedia of Chemical Technology
John Wiley & Sons · Reference work
Relied on for: That EDTA is an aminopolycarboxylate chelating agent that sequesters metal ions across a wide range. (background and mechanism only)