Short for disodium ethylenediaminetetraacetic acid. Used as a chelating agent in cosmetic products, meaning it prevents ingredients in a formula from binding with trace elements (mainly minerals) that can be present in water. Studies have found that EDTAs, including disodium EDTA, as used in cosmetic formulations are safe.
References for this information:
European Commission Directorate General for Health and Consumers. Cosmetic Ingredient Glossary; Substance: Disodium EDTA. [Internet]. 2015 [cited 2015 Sept]. Available from: http://ec.europa.eu/growth/tools-databases/cosing/index.cfm?fuseaction=search.details_v2&id=33604
International Journal of Toxicology, 2002, Supplement 2, pages 95-142