What is it?
The potassium salt of acetic acid, the acid that gives vinegar its sour taste. In cosmetics it is used as a buffering agent, which helps keep a product’s pH stable, and it has also been listed as a fragrance ingredient. Cosmetic use is uncommon; the industry data reviewed by safety experts showed it in nail creams and lotions. It is also a permitted food additive, E261, used as an acidity regulator and preservative.
Key information
- Potassium acetate is the potassium salt of acetic acid, the acid in vinegar.
- The CIR Expert Panel concluded that acetic acid and its salts, including potassium acetate, are safe in the present practices of use and concentration.
- The only reported cosmetic use in the CIR review was at 3 percent in nail creams and lotions.
- WHO and FAO food additive experts set no numerical limit on daily intake for acetic acid and its potassium and sodium salts.
More information
The Cosmetic Ingredient Review (CIR) Expert Panel assessed potassium acetate together with acetic acid, several other acetate salts and a group of acetate esters, because enzymes in the skin break those esters down into acetic acid. The panel concluded that all of them are safe in the present practices of use and concentration, and its final report was published in 2012. In the industry survey the panel reviewed, potassium acetate was reported at 3 percent in nail creams and lotions, while no products containing it had been registered in the FDA’s voluntary reporting program at the time.
The available safety data point to low toxicity. The oral dose that killed half of the test rats was 3,250 mg per kg of body weight, a high figure. Metal acetate salts were described as minor eye irritants in animal studies.
As a food additive, potassium acetate is E261, used as an acidity regulator and preservative. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) evaluated acetic acid and its potassium and sodium salts as a group in 1973 and set an acceptable daily intake of “not limited,” meaning it saw no need for a numerical limit, a position it maintained in 1997. On labels it appears as potassium acetate.
Sources: Cosmetic Ingredient Review: Methyl acetate, simple alkyl acetate esters, acetic acid and its salts, draft final report (2010); Cosmetic Ingredient Review: Quick reference table of ingredient findings (September 2020); WHO JECFA database: Potassium acetate
