Peracetic Acid As a Disinfectant

Peracetic acid is a relatively new disinfectant created by mixing acetic acid and hydrogen peroxide in a water solution. It has been used in the food industry for purposes such as disinfecting slaughterhouses and in the medical industry as a method of sterilizing equipment, with other applications in water purification.

How It Works

• As a disinfectant, peracetic acid works because it oxidizes the outer cells of microorganisms. Both chlorine dioxide and sodium hypochlorite produce oxidation, but to a lesser degree than peracetic acid. This oxidation of microorganisms effectively deactivates them. Peracetic acid also works against viruses, bacteria, yeasts, molds and spores. It also works to prevent the formation of biofilm, which is a layer of microorganisms that forms on surfaces that are in contact with water, such as water towers and cisterns.

Changes in Efficiency

• The efficiency of the acid is influenced by its pH level and the temperature. It’s most effective with a pH value of 7 and less so when the pH ranges between 8 and 9. A greater amount of the acid has to be used as the temperature decreases. At a temperature of 59 degrees Fahrenheit, five times more peracetic acid is required to be effective than at a temperature of 95 degrees Fahrenheit.

Non-corrosive

• Some disinfectants can be damaging to metals, leading to corrosion. However, peracetic acid has a much lower rate of corrosion compared to other acid media. The results of an evaluation of peracetic acid’s effectiveness published in the Indian Journal of Medical Microbiology suggested that sterilization with peracetic acid caused minimal corrosive damage to dental instruments. Some hospitals, however, do not approve peracetic acid for use on some medical instruments including angioscopes, surgiscopes and bone flaps.

Environmental Effects

• Oxidizing disinfectants are those that generate active forms of oxygen. Such oxidants include hydrogen peroxide and peracetic acid and these products tend to create fewer byproducts than disinfectants with other active ingredients, such as chlorine or the nitrogen found in some compounds. Fewer byproducts means fewer toxins released into the environment.

Dangers

• At some concentrations--1,500 to 2,500 parts-per-million--peracetic acid has been shown to be cytotoxic. This means that if peracetic acid comes into direct contact with cells, it can cause damage to the cells and to the DNA. At lower concentrates, such as 800 ppm, this effect was found to be significantly reduced. However, the only ones likely to come into direct contact with peracetic acid in high enough concentrations are those working with it and trained in its use.