How does tetrasodium EDTA work in cleansers?

Washing hands with soap.
Tetrasodium EDTA in your skin cleanser helps you get clean when using hard water. See more pictures of unusual skin care products.
© Mitic

Many people take soap for granted. We know it works, but we don't know why. We base our purchasing decisions on brand names and price more than we do on ingredients, and who can blame us? Trying to read the ingredients on the back of a shampoo bottle can be like trying to read a foreign language for the first time. But if you tried, you might find tetrasodium EDTA mixed in with all those other hard-to-pronounce chemical compounds. It's a common ingredient in cleansers such as shampoo and hand soap, and you'd have a hard time getting clean without it.

Tetrasodium EDTA is used as a chelating agent, or to put it in layman's terms, it makes hard water become soft. As water makes its way through the water cycle, it sometimes picks up metal ions such as calcium and iron. These metal ions can make water hard, which is a problem because hard water won't get you clean. Body washes, shampoos and other cleansers work as surfactants, which are responsible for attracting dirt and oil and pulling it off your skin so it can be rinsed away by water. The only problem is that surfactants also attract the metal ions found in hard water, hindering the surfactants' ability to cleanse your skin. That's where tetrasodium EDTA comes in. As the chelating agent, it neutralizes the metal ions in hard water and allows the surfactant to do its job. The end result is soft water and squeaky clean skin [source: Parbhoo].


Some research on this chemical compound show that it is safe when used in small amounts as recommended [source: Cosmetic Independent Review]. The same principles that make tetrasodium EDTA effective in skin cleansers also make it effective in automobile and household cleaning products [source: U.S. Department of Health and Human Services].

Keep reading for lots more information on why tetrasodium EDTA is so effective as a chelating agent.


Lots More Information

Related HowStuffWorks Articles

  • Cosmetic Ingredient Review. "Cosmetic Ingredient Findings: 1976 to present." July 18, 2009. (Accessed 9/2/2009)
  • Parbhoo, Rupesh. "A Chemical Engineer's Guide to Cleaning Just About Anything." Illumin. Issue II, Vol. 10. 2008. (Accessed 09/06/2009)
  • U.S. Department of Health and Human Services. "Household products database: Tetrasodium EDTA." September 2009. (Accessed 9/21/2009)
  • University of Maryland Medical Center. "Ethylenediaminetetraacetic Acid (EDTA)." June 7, 2007. (Accessed 9/21/2009)