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The Many Uses and Hazards of Peracetic Acid
BY KAY BECHTOLD

Peracetic acid (CAS No. 79-21-0), also known as peroxyacetic acid or PAA, is an organic chemical compound used in numerous applications, including chemical disinfectant in healthcare, sanitizer in the food industry, and disinfectant during water treatment. Peracetic acid has also previously been used during the manufacture of chemical intermediates for pharmaceuticals. 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. Many users know peracetic acid to be versatile and effective, and professionals with environmental responsibilities consider it to be environmentally friendly due to its decomposition products, which include acetic acid, oxygen, and water. However, industrial hygienists recognize that it is also highly corrosive and a strong oxidizer, and exposure to peracetic acid can severely irritate the eyes, skin, and respiratory system.

MANY ADVANTAGES “I’ve never seen a chemical whose applications cross over from food and beverage to wastewater,” says Debbie Dietrich, CIH, senior vice president of sales and marketing and corporate industrial hygienist at SKC Inc. “From an industrial standpoint, there are so many advantages to peracetic acid: it’s easy to apply and it doesn’t leave any toxic residues.”
Dietrich, who first learned about peracetic acid from the AIHA Healthcare Working Group, was surprised to find that the use of the compound extends far beyond the healthcare industry, where it’s primarily used as a chemical disinfectant. Outside of hospitals, peracetic acid has a wide variety of applications, including as a preventive additive to control bacteria such as Legionella in cooling towers and as a biocide to inhibit microbes in wastewater treatment. It’s even used for bleaching and wastewater treatment in the pulp and paper industry. In the food industry, peracetic acid is an effective antimicrobial used during poultry processing, to wash fresh produce, to sanitize surfaces, and more.
Christine R. Knezevich, CIH, an industrial hygienist for the U.S. Air Force who has previous experience working in the food industry and for a manufacturer/distributor of peracetic acid, agrees that the compound has many advantages.
“What’s so wonderful is it’s no-rinse,” Knezevich, a former Safe Quality Food (SQF) practitioner, explains. She adds that because peracetic acid functions well at cold temperatures it can be used effectively in freezers and coolers where meat processing occurs. And some peracetic acid products can be used for more than one task.
“The great thing about peracetic acid is that depending on the product registration and instructions for use, you can use it for multiple purposes: as a sanitizer, a disinfectant, or a sterilizer,” she explains. “Many times, it’s just a matter of the contact time and the concentration.”
According to Knezevich, peracetic acid doesn’t pose an issue for facilities with water discharge permits under EPA’s National Pollutant Discharge Elimination System (NPDES) permit program. The chemical compound is found on the agency’s Safer Chemical Ingredients List as an antimicrobial active that EPA has “verified to be of low concern based on experimental and modeled data.” Peracetic acid is especially attractive to companies who are under pressure to use greener chemicals—particularly those that are certified under the ISO 14001 Environment Management System standard. Knezevich explains that large companies evaluate suppliers based on these “green” requirements. HAZARDS The International Chemical Safety Card (ICSC) for stabilized peracetic acid warns of short-term exposure effects, noting that “the substance is corrosive to the eyes, the skin and the respiratory tract.” Symptoms of acute exposure may include cough, labored breathing, and shortness of breath; skin redness, pain, and blisters; and “severe deep burns” in the eyes, according to the ICSC, which is available on NIOSH’s website. While peracetic acid is highly irritating to those who work with it—manufacturing workers are most at risk, along with chemists studying the compound—Knezevich maintains that the primary concern associated with peracetic acid is that it’s a strong oxidizer.
“Our major concerns were actually the fire and explosion hazards and reactivity issues,” she says, explaining that peracetic acid reacts violently with soft metals such as brass, copper, iron, and zinc. And at concentrations of 15 percent or higher, a major chemical manufacturer, FMC Corporation, recommends explosion-proof equipment.
But for products containing concentrations of peracetic acid of five percent or less, which is what the majority of industries are dealing with, the biggest worry is that the compound will come into contact with the wrong type of metal, says Knezevich. She describes a mishap in which a galvanized steel dip tube was installed through the bung of a 55-gallon drum of a solution containing peracetic acid. The drum was laid horizontally in its cradle over the weekend so it would be ready for use the following week. The soft metals of the dip tube reacted with the peracetic acid, resulting in a buildup of oxygen gas. Sometime over the weekend, the drum ruptured from the heat and pressure of the reaction, releasing its contents onto the floor. Had staff been in the facility during that time, they likely would have noticed something was wrong.
“They would have noticed that it was starting to bulge or foam,” Knezevich says. “I’ve worked for chemical companies that made products with peroxide, and, believe me—you’ll know when something has gone wrong.”
Workplaces using peracetic acid at lower concentrations will preferably have some type of chemical metering pump system in place to minimize exposures to workers. During a roundtable presentation on surface disinfectants at AIHce 2013, Knezevich described how such a system can be set up in a space such as a janitor’s closet and be used to add water to concentrated peracetic acid products. Figure 1 depicts an example of a dispensing system. Some companies that sell peracetic acid products will also help set up and train workers on chemical dispensing equipment.
Editor’s note: The mention of specific products, companies, or services does not constitute endorsement by AIHA® or The Synergist®.
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Figure 1. Chemical metering pump system that works by chemical proportioning through Dosatron pumps (left) and the transferring of chemicals through air pumps (right).

Tap on the image to open a larger version in your browser.
Knezevich stresses the importance of employee training and safety precautions when dealing with peracetic acid.

“Worker education doesn’t end with the people handling [the peracetic acid],” she says. “If you have personnel doing maintenance work, they have to understand what can and cannot be used with that system.”
Knezevich prefers annual training to ensure that employees fully understand the hazards of peracetic acid. Workers and others handling products containing peracetic acid should also be sure to follow the manufacturer’s instructions for use on technical information sheets that accompany each product. These sheets provide directions for use, including instructions for diluting the product, if necessary; chemical characteristics; safety and handling; and storage and disposal. EXPOSURE LIMITS While OSHA does not currently have a permissible exposure limit (PEL) for peracetic acid, IH and OEHS professionals are not entirely without guidance.
In 2014, ACGIH adopted a Threshold Limit Value–Short-Term Exposure Limit (TLV-STEL) for peracetic acid of 0.4 ppm (1.24 mg/m3) as a 15-minute time-weighted average (TWA) exposure that should not be exceeded at any time during a workday. The ACGIH STEL value carries the Inhalable Fraction and Vapor (IFV) endnote, which indicates that peracetic acid “may be present in both particle and vapor phases” and signals IHs to consider both phases when assessing exposures. The adverse health effects on which the TLV-STEL is based are upper respiratory tract, eye, and skin irritation.
In 2010, the technical documentation supporting an Acute Exposure Guideline Level (AEGL) for peracetic acid was published in the eighth volume of Acute Exposure Guideline Levels for Selected Airborne Chemicals published by the National Academies Press. AEGLs, or exposure levels below which adverse health effects are not likely to occur, set threshold exposure limits for the general public and are applicable to emergency exposures ranging from 10 minutes to eight hours. They are established at three levels, with AEGL-1 representing the least severe toxic effects caused by exposure and AEGL-3 representing a level of exposure that could cause life-threatening health effects or death. The AEGL-2 for peracetic acid, which indicates the level at which exposure could cause serious, long-lasting adverse health effects, is 0.5 ppm (1.6 mg/m3). A table outlining all AEGLs for peracetic acid is published on EPA’s website.
Most recently, this past August NIOSH reopened for comment its draft Immediately Dangerous to Life or Health (IDLH) value profile for peracetic acid. The profile summarizes the health hazards of acute exposures to high airborne concentrations of peracetic acid and discusses the rationale for the proposed IDLH value. The draft document lists the IDLH value for peracetic acid as 0.64 ppm (1.7 mg/m3). The agency does not currently have a recommended exposure limit (REL) for the compound.
Exposure guidelines for peracetic acid are limited, but Knezevich notes that because it’s most often sold as a mixture with hydrogen peroxide and acetic acid, there are other ways for IHs to measure worker exposure to those chemicals.
“You simply don’t have a limit for peracetic acid, so the next step is to look at what else is in the mixture,” she says.
Workplaces using peracetic acid at lower concentrations will preferably have some type of chemical metering pump system in place to minimize exposures to workers.
Fortunately, the OSHA PELs, ACGIH TLVs, and NIOSH RELs cover both hydrogen peroxide and acetic acid. All three organizations have set their respective exposure limits at 1 ppm, or 1.4 mg/m3 TWA, for hydrogen peroxide. ACGIH notes that hydrogen peroxide is a “confirmed animal carcinogen with unknown relevance to humans.” The PEL, TLV, and REL for acetic acid are all set at 10 ppm, or 25 mg/m3 TWA. ACGIH and NIOSH both adopted a STEL for acetic acid at 15 ppm, or 37 mg/m3. SAMPLING AND ANALYTICAL METHODS The only method currently available for sampling peracetic acid was published in 2004 by the Institut National de Recherche et de Sécurité (INRS), a French research organization similar to NIOSH. The INRS method is for the simultaneous collection of peracetic acid and hydrogen peroxide because the two are found together in solutions. It took U.S. laboratories some time to begin analyzing samples using this method, but growing interest spurred several AIHA-accredited labs to offer the analysis over time, Dietrich says. SKC offers the media for the French method—two-section and single sorbent tubes for sampling peracetic acid, preceded by a treated glass filter for hydrogen peroxide.
Bureau Veritas has been offering analysis for peracetic acid for at least two or three years. Kristine Kurtz, PhD, a department supervisor who is involved in method development and validation at Bureau Veritas’ Novi, Mich., laboratory, says that her lab analyzes five to ten samples a week for peracetic acid. Kurtz explains that most people use the two-section sorbent tubes for collection and that the media is silica gel that’s been treated with methyl p-tolyl sulfoxide, or MTSO.
“During collection, the peroxyacetic acid oxidizes the MTSO from the sulfoxide into the sulfone, so the actual analyte that we’re dealing with is the oxidation product, or MTSOO,” Kurtz says. “In order to report out results as peroxyacetic acid, we use a conversion factor to convert the oxidation product that we’re actually using in the analysis back to peroxyacetic acid.”
Dietrich says that when the media was first developed, laboratory professionals and others approached SKC with two concerns. One was that the method might not be accurately capturing the peracetic acid.
“Results were coming out as below the ACGIH TLV-STEL, but workers were still complaining of irritation,” she says.
Another concern was that the background level on the sampling media was too high. Dietrich says that SKC put the media on hold to investigate the concerns with laboratory partners.
SKC ultimately found a different reagent to lower the background levels of the company’s sorbent tube and worked with laboratory partners to verify that the INRS method worked with the media available. Kurtz says the improved media has allowed her laboratory to lower its reporting limit for peracetic acid to 5 micrograms.
Both Dietrich and Kurtz stress the importance of using a flow rate of at least 1 L/min when using a filter and tube in series to sample for these chemicals.
“Our tests showed that the method was capturing the chemical as long as you kept the flow rate at 1 liter per minute,” Dietrich says. “And it’s not easy—a lot of sampling pumps really struggle to pull 1 liter per minute through this sampling media because it has a very high pressure drop. Even if it drops to 800 milliliters per minute, you will see a drop in the recovery.” FUTURE SOLUTIONS In January, OSHA published Method 1019 for hydrogen peroxide based on the INRS sampling and analytical method for the chemical. OSHA Method 1019 uses the same filter media as the French INRS method and is available on OSHA’s website.
Knezevich would like to see a PEL for peracetic acid. She describes the balancing act that often challenges professionals who are responsible for health and safety as well as environmental issues.
“We have this great product, and having more information on occupational exposure limits would help guide industrial hygienists” who currently rely mostly on their professional judgment in terms of peracetic acid, she says. “How do you find something that’s safe for workers, effective, and doesn’t cause any environmental effects?”
Dietrich is hopeful that new solutions related to peracetic acid are forthcoming, citing how government agencies, practitioners, and vendors collaborate when there are industrial hygiene problems to solve.
“The global IH profession has once again come together to address the hazards of peracetic acid,” Dietrich says. “Everybody’s working to ensure that workers are safe when dealing with this chemical that has so many uses and so many advantages.” KAY BECHTOLD is assistant editor of The Synergist. She can be reached at kbechtold@aiha.org or (703) 846-0737. Acknowledgment: The Synergist thanks Debbie Dietrich, Christine Knezevich, Kristine Kurtz, Bob Lieckfield, and members of the Healthcare Working Group—including Melissa McCullough, Erica Stewart, and Steve Derman—for their time and assistance in developing this article.
NIOSH: External Review Draft “Immediately Dangerous to Life or Health (IDLH) Value Profile for Peracetic Acid [CAS No. 79-21-0]” (PDF, March 2015).
Synergist Solutions: “A Global Focus on the Hazards of Peracetic Acid” (PDF, May 2014).
The Annals of Occupational Hygiene: “Simultaneous Sampling of Peroxyacetic Acid and Hydrogen Peroxide in Workplace Atmospheres” (November 2004).
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Although the print version of The Synergist indicated The IAQ Investigator's Guide, 3rd edition, was already published, it isn't quite ready yet. We will be sure to let readers know when the Guide is available for purchase in the AIHA Marketplace.
 
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- Ed Rutkowski, Synergist editor
Disadvantages of being unacclimatized:
  • Readily show signs of heat stress when exposed to hot environments.
  • Difficulty replacing all of the water lost in sweat.
  • Failure to replace the water lost will slow or prevent acclimatization.
Benefits of acclimatization:
  • Increased sweating efficiency (earlier onset of sweating, greater sweat production, and reduced electrolyte loss in sweat).
  • Stabilization of the circulation.
  • Work is performed with lower core temperature and heart rate.
  • Increased skin blood flow at a given core temperature.
Acclimatization plan:
  • Gradually increase exposure time in hot environmental conditions over a period of 7 to 14 days.
  • For new workers, the schedule should be no more than 20% of the usual duration of work in the hot environment on day 1 and a no more than 20% increase on each additional day.
  • For workers who have had previous experience with the job, the acclimatization regimen should be no more than 50% of the usual duration of work in the hot environment on day 1, 60% on day 2, 80% on day 3, and 100% on day 4.
  • The time required for non–physically fit individuals to develop acclimatization is about 50% greater than for the physically fit.
Level of acclimatization:
  • Relative to the initial level of physical fitness and the total heat stress experienced by the individual.
Maintaining acclimatization:
  • Can be maintained for a few days of non-heat exposure.
  • Absence from work in the heat for a week or more results in a significant loss in the beneficial adaptations leading to an increase likelihood of acute dehydration, illness, or fatigue.
  • Can be regained in 2 to 3 days upon return to a hot job.
  • Appears to be better maintained by those who are physically fit.
  • Seasonal shifts in temperatures may result in difficulties.
  • Working in hot, humid environments provides adaptive benefits that also apply in hot, desert environments, and vice versa.
  • Air conditioning will not affect acclimatization.
Acclimatization in Workers
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