5 min read

Characteristics of PAA

Published on
May 18, 2023

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PAA or Peracetic Acid has been somewhat of a buzzword in recent years, not only in the safety and health world, but across numerous well-known industries. The use and market share of this chemical has grown rapidly in the last 5 years, due to its myriad of applications, its ease of use, effectiveness, and the fact that it does not leave behind any toxic residues. With its many advantages, it is hard to find another chemical like it. 

PAA is instrumental in ensuring that a variety of products are safe for consumer use. It is a chemical that serves as both a disinfectant and sanitizer in the healthcare, wastewater treatment, food industries, and beyond. Produced by reacting acetic acid and hydrogen peroxide with an acid catalyst, peracetic acid is always sold in stabilized solutions containing acetic acid, hydrogen peroxide, and water. For the food and healthcare industries, peracetic acid is typically sold in concentrates of 1 to 5 percent and is diluted before use. 

PAA can also be known as peroxyacetic acid, peracetic acid, periacetic acid, or per acid. It is a clear, colorless liquid, known for being a strong oxidizing agent. Those electrons you see in the above chemical structure play an important role in making PAA such a successful disinfectant. It usually has a strong, vinegar (acetic acid)-like odor. PAA degrades rapidly, leaves little to no residue, and decomposes into relatively harmless naturally occurring substances. Its decomposition products are acetic acid, oxygen, and water. It is known for being environmentally friendly because, unlike other sanitizers, no rinse is required. PAA can be used as a sanitizer, disinfectant, or sterilizer; it is just a matter of contact time and concentration.

How is it so effective? The reason for the excellent and rapid antimicrobial effects of peracetic acid is its specific capability to penetrate the cell membrane. It does this through the process of oxidation - remember all those electrons? In the most basic terms, oxidation is the transfer of electrons. PAA disinfects by oxidizing the outer cell membrane of bacterial cells, endospores, yeast, mold spores, and other types of cells. Inside the cell, it denatures proteins, disrupts cell wall permeability, and oxidizes sulfur bonds in enzymes. PAA irreversibly disrupts the cell's systems and destroys it.

Is there a downside? Or is PAA an invincible powerhouse? Despite the significant benefits of PAA use, there are concerns about the health and safety of those exposed to it while working with the chemical. PAA in high concentrations can be corrosive and cause mild to severe irritation of the eyes, nose, and upper respiratory system. Proper handling and taking recommended precautions while using or applying PAA is essential. For industrial hygienists, accurate quantification of PAA in the air remains challenging, as it rapidly degrades into its constituents of acetic acid and hydrogen peroxide, and sampling methodologies are still being developed by both governmental agencies and private companies. This makes it difficult to determine concrete occupational exposure limits, a work in progress by private industry and governmental industries alike.

In conclusion, it is safe to say that the hype around PAA is not without merit. The list of applications and uses of PAA will continue to grow, as will our knowledge on how to quantify and safely use it. It is an exciting time to be in this industry. Morgan Henrie.