October 21, 2013
What Is…Peracetic Acid?
By Michael D. Shaw
OK, the headline is not quite as catchy as “Who is John Galt?” but hopefully, it piqued your curiosity. Peracetic acid—aka Peroxyacetic acid and often abbreviated as PAA—is a highly effective antimicrobial, used in a wide range of applications, primarily in the food industry and health care settings. PAA disinfects by oxidizing the outer cell membrane of bacterial cells, endospores, yeast, and mold spores. The commercial product is an equilibrium solution of peracetic acid, hydrogen peroxide, acetic acid, and water.
It is also employed as a bleaching agent in the paper and textile industries, and in chemical synthesis. In certain settings, PAA has been replacing chlorine and chlorine dioxide, owing to its higher oxidation potential, as well as its non-toxic degradation products—ultimately carbon dioxide, oxygen, and water. Indeed, PAA is widely used in Europe for wastewater disinfection.
Related to the food industry applications is PAA’s growing presence in the horticultural and aquatic industries. In a recent publication, Jeff Rich of BioSafe Systems—manufacturer of peracetic acid-based products for that space—sets the record straight:
The horticultural and aquatic industries are riddled with exposure to hard and soft chemistries, yet there is a lingering misconception of “green chemistry” or “soft chemicals.” Many people disregard the dangers of “hard chemicals” and falsely claim that they are cheaper and more effective. It is common for greenhouses to use chlorine and acids to clean and lower the pH, even though this practice can be unsafe. If incorrectly combined, these two chemistries can form a noxious gas that is harmful to people.
He informs his readers that the degradation products of PAA not only leave no harmful residual, the added oxygen and water increase plant vigor. Rich also discusses the matter of pathogen mutation and eventual resistance. “Most [other] fungicides and bactericides are geared towards selecting specific pathogens. If 12% of a targeted pathogen survives a round of spraying, most will be resistant to the next round of spraying.”
Rich notes that even if growers spray on a rotational basis to avoid such consequences, toxic residuals are still involved. And with peracetic acid, the pathogens are killed virtually upon contact, reducing the likelihood of resistance mutations.
As to health care, even though the anti-bacterial properties of PAA had been known since the early 1900s, the chemical gained two major boosts in popularity over the last 50-odd years. In January 1960, a breakthrough paper entitled “The virucidal properties of peracetic acid” by Kline and Hull was published in the American Journal of Clinical Pathology. This was followed in the 1990s by the emergence of endoscopic procedures, along with the continuing interest in finding an alternative to glutaraldehyde, as the high-level disinfectant of choice. An entire industry of so-called automated endoscope reprocessors would emerge, many of which are based on peracetic acid disinfectants.
Within the realm of health and hygiene, food safety is about as basic as it gets. Chickens, especially, have come under close scrutiny since they are notoriously plagued with Salmonella and/or Campylobacter, the leading bacterial causes of food-borne disease.
Tom Super—of the National Chicken Council—reminds us, “It is always important to consistently follow safe food handling and cooking practices because all raw agricultural products—whether it’s produce, fruit, meat or poultry—could contain naturally occurring bacteria that might make someone sick. But, there are steps people can take in the home to significantly reduce their risk.”
Chlorine bleach solutions have been in widespread use in the US poultry industry for decades, and have spawned international trade disputes, as well as domestic worker safety issues. A few days ago, I caught up with Dr. John Dankert, Chief Scientific Officer of Synergy Technologies, Inc. Synergy provides an advanced line of processing aids and antimicrobial products targeting such pathogens as Salmonella, E. coli, Listeria and Campylobacter. Peracetic acid is an important component of Synergy’s products.
John has a distinguished background in all matters of decontamination/disinfection, in fields ranging from the military to food safety. He summarized the key benefits of his company’s products: “Poultry processing employees can be overcome with chlorine fumes, and if they are off the line, the plant loses $1000 per minute. What we do is make food safety as foolproof as possible—all under the watchful eye of the USDA.”
Finally, even though peracetic acid-based products have significant safety advantages over older formulations, they are by no means benign, and interest has risen in monitoring the air for this compound in affected environments. A key player here is Interscan Corporation, currently deploying its instruments into the food industry, after a successful introduction in health care.
Now you know what peracetic acid is.