Peracetic acid

(Peroxyacetic acid; acetyl hydroperoxide)

CAS 79-21-0

Note: Although other percarboxylic acids have different physical properties, their reactivity and toxicology are similar to those of peracetic acid.





Physical Properties

Colorless liquid

bp 105 °C (40% solution in acetic acid), mp 0.1 °C

Miscible with water



Acrid odor


Vapor Pressure



Flash Point

40.5 °C (open cup)


Autoignition Temperature

Explodes when heated to 110 °C


Toxicity Data

LD50 oral (rat)

1540 mg/kg


LD50 skin (rabbit)

1410 mg/kg

Major Hazards

Severely irritating to the eyes, skin, and mucous membranes; can form explosive mixtures with easily oxidized substances.


The acute toxicity of peracetic acid is low. However, peracids are extremely irritating to the skin, eyes, and respiratory tract. Skin or eye contact with the 40% solution in acetic acid can cause serious burns. Inhalation of high concentrations of mists of peracetic acid solutions can lead to burning sensations, coughing, wheezing, and shortness of breath.

Peracetic acid has not been found to be carcinogenic or to show reproductive or developmental toxicity in humans. There is some evidence that this compound is a weak carcinogen from animal studies (mice).

Data on other peracids suggest peracetic acid may show the worst chronic and acute toxicity of this class of compounds. Other commonly available peracids, such as perbenzoic acid and m-chloroperbenzoic acid (MCPBA) are less toxic, less volatile, and more easily handled than the parent substance.

Flammability and Explosibility

Peracetic acid explodes when heated to 110 °C, and the pure compound is extremely shock sensitive. Virtually all peracids are strong oxidizing agents and decompose explosively on heating. Moreover, most peracids are highly flammable and can accelerate the combustion

The National Academies of Sciences, Engineering, and Medicine
500 Fifth St. N.W. | Washington, D.C. 20001

Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement