Paying Attention to Peracetic Acid
You use it. You smell it. But what is Peracetic Acid (PAA)? Also known as peroxyacetic acid, PAA is a disinfectant used in healthcare and many other industries. It is a highly effective antimicrobial/biocide showing good efficacy against a broad spectrum of pathogens. PAA typically occurs as an equilibrium mixture of acetic acid (the acid in vinegar) and hydrogen peroxide (H2O2). After use and upon reaction, PAA breaks down to acetic acid and water, with no harmful byproducts, giving it its environmental friendly qualities. However, even though PAA is environmentally friendly, it is unfortunately not employee friendly. It is a highly corrosive chemical that can severely irritate and burn the skin and eyes, and vapors can cause irritation as well. It is important to take safety precautions (according to manufacturers’ instructions) when working with and around Peracetic Acid.
Further information on Peracetic Acid can be found at:
• National Library of Medicine, Hazardous Substances Data Bank https://pubchem.ncbi.nlm.nih.gov/source/hsdb/1106
• CDC Guideline for Disinfection and Sterilization https://tinyurl.com/y8qw2vq3
Peracetic Acid (PAA) is commonly used as a high level disinfectant for reprocessing endoscopes in hospitals & ASCs. Major manufacturers of Automatic Endoscope Reprocessors (AERs) utilize Peracetic Acid in their disinfection chemistry, and it is sometimes used in Environmental Services to disinfect rooms. Hospitals will either wash down a room or ‘fog’ a room with PAA vapor, thus killing any bacteria, viruses, and spores on the surfaces in the room. However, PAA vapors are dangerous to people if inhaled. In this way, PAA vapor is similar to smoke: smoke can be used to preserve meat (since it is antimicrobial), but smoke can also harm a person should they breathe too much of it in. As a stronger antimicrobial agent, PAA is more toxic to people than smoke, and a room being washed down or fogged should be continuously monitored to ensure employees are not over-exposed to PAA vapors.
The method by which PAA attacks pathogens is through the reaction with the cellular walls. This reaction leads to the breakdown of cell membranes and cellular death due to cell content leakage. It is similar to popping bubble wrap or a water balloon: the contents of the item spill out, making the item lose shape. Rupturing the cell wall or cell membrane will result in the cell’s death. In addition to reacting with the cell membrane, PAA reacts with and interrupts various processes inside the cell. Once inside, PAA acts on the bases of DNA molecules, hindering cellular replication. PAA will also interfere with molecular functions by reacting with double bonds. In summary, PAA can destroy cells through a variety of attacks!
For more information on the mechanisms of PAA in the inactivation of microbes:
Microbes are tiny microorganisms that can be primarily classified into four groups: bacteria, viruses, fungi, and protozoa. Humans and microbes share the same biological heritage of much of the microbial kingdom, and both are made up of living cells. Since Peracetic Acid (PAA) is a broad spectrum antimicrobial, it will kill or harm practically any living organism. While PAA is targeted for use at inactivating living microbes, it presents a hazard to humans as well. PAA makes no distinction in damaging the cells of dangerous microorganisms and damaging healthy human cells. As such, it is important to take measures to prevent your employees from being unnecessarily exposed to PAA.
PAA can cause a combination of harmful medical effects, including eye irritation and damage, shortness of breath and respiratory irritation, skin redness, irritation, and blisters, along with pulmonary edema (the build-up of fluid in the lungs). Plus, PAA can present a number of physical hazards as well, since it is a strong oxidant. PAA reacts with combustible fuels such as paper, so sawdust must never be used to clean up PAA spills. PAA will also react with many common metals, such as brass, copper, iron, and zinc and will cause severe corrosion. These metals and their ions can cause PAA to decompose, sometimes violently.
For more information on PAA’s Health Risks, check out this Safety Data Sheet on Peracetic Acid:
Unlike many sterilant chemicals, PAA CAN be smelled at fairly low concentrations. However, few people can determine the concentration of PAA in the air from smell alone. As such, employees can’t assess the risk of over exposure, even though they can smell the PAA in the air. Often, people will get used to the vinegar-like smell of PAA due to olfactory fatigue. This is similar to how people do not notice the smell of their own homes, but do notice the smell of other people’s houses because it is a new environment with new smells. With olfactory fatigue, workers may eventually not be able to smell the PAA at all.
While PAA automated endoscope reprocessors (AERs) are well designed and have many fail safes, there is a possibility that they may leak or fail. This situation is analogous to cars: they have many safety features, but for a variety of reasons they may cause someone to die in an accident. It could be the impact (despite all the many safety features that cars have) or human error (like a passenger not wearing a seatbelt). Similarly, PAA AERs can fail or leak for many reasons, ranging from a mechanical failure to human error, such as inappropriate handling of the "empty" PAA bottle. Unless a department is using continuous monitoring, the employees may not know to what extent they are being exposed until it is too late, and the health damage has already been done. With the possibility of equipment vapor leaks (even if the chance is remote), continuous monitoring is an important safeguard to protect department employees from the worst-case scenario.
While PPE can protect workers from experiencing certain types of injuries from PAA, such as how gloves can protect against chemical burns, most masks used in healthcare will not filter out PAA vapors and protect against respiratory damage or irritation.
For an example from the FDA regarding human error (improper handling of PAA), where PPE did not prevent exposure to PAA:
For an example from the FDA regarding a mechanical error (equipment leak), where PPE did not prevent exposure to PAA:
Failure or poor performance of ventilation systems can cause problems, and potentially harm the employees by not removing all PAA vapor that may be present. Under-performing ventilation can cause a buildup of PAA vapors, exposing employees in the space to concentrations of PAA over the Short-Term Exposure Limit (STEL). Use of continuous monitoring methods could reveal inadequacies in the ventilation system and allow for prompt intervention for employee safety.
How many AER cycles are you running each day? There is a trend with high level disinfection and sterilization technologies towards faster and faster cycle times in Sterile Processing and Endoscopy settings. Thanks to PAA being an effective cold-temperature high level disinfectant, endoscopes can now be cleaned in about 30 minutes. As such, the endoscopes can now be used and processed more often, reducing inventory needs. However, more cycles means more chances for employees to potentially be harmed by leaking PAA. Malfunctions, human error, and poor ventilation can all result in worker exposure to PAA. As such, it is important to continuously monitor for PAA in order to ensure your employees stay safe.
For more information on PAA's effective microbicidal activity:
OSHA regulates employee exposure to chemicals by issuing Permissible Exposure Limits (PELs). Currently there is no OSHA PEL or NIOSH REL for PAA, but there is an ACGIH Threshold Limit Value (TLV) of 0.4 ppm as a 15-minute Short Term Exposure Limit (STEL) and “Cal-OSHA has proposed 0.2 ppm as an 8 hr TWA PEL,” (https://www.cdc.gov/niosh/hhe/reports/pdfs/2017-0114-3357.pdf).
Even though there is no OSHA PEL, OSHA can and has fined employers for not providing a safe work environment under the General Duty Clause, (Sec. 5a Occupational Safety and Health Act of 1970) which states “Each employer shall furnish to each of his employees employment and a place of employment which are free from recognized hazards (like peracetic acid) that are causing or are likely to cause death or serious physical harm to his employees.” (https://tinyurl.com/yaucj4ab)
The best way to ensure your workers’ safety in a workplace with PAA is continuous monitoring. By having a continuous monitor for PAA above or next to the AER, employees can have real time readings of their environment, and will be able to react quickly to any leaking vapors that may put them in danger. Most AERs work well, but as with any equipment, problems can occur. It's like putting a carbon monoxide alarm in your home: you don’t expect a carbon monoxide leak, but it's better to have an alarm, just in case.
Preventative Maintenance on an Automated Endoscope Reprocessor (AER) is an important part of keeping employees safe from PAA over-exposure. However, equipment failures and human error do not just happen on some kind of a regular PM schedule, and so real time monitoring is required to ensure a prompt response to any leaks. Continuous monitoring provides advanced indication of the need for maintenance of equipment in real time. Small leaks detected early alert the user to the need for maintenance or repair, reducing the risk of over-exposure to PAA.
The short answer to this question is NO. PAA is normally found as a mixture with acetic acid and H202 in varying ratios. An H202 monitor will only be able to detect the H202 vapors, but it will not be able to detect the PAA vapors present. In mixtures with a high PAA content, PAA is the dominant toxic vapor present in the air and is more hazardous than the H202 or acetic acid that may be present. Using an H202 monitor in this situation may show an acceptable reading for H202, but the vapors contain a hazardous amount of PAA. The best strategy to designing a gas detection system is to assess which vapor presents the greater hazard and detect that one.
For more information on continuous monitoring of PAA:
You may be surprised to discover how much Peracetic Acid touches your life outside of healthcare. It is used in a variety of industries ranging from water treatment to cleaning fresh produce. This is because when PAA reacts, it breaks down into water, oxygen, and acetic acid, making it environmentally safe to use in sterilization, high level disinfection, and food processing. PAA’s primary use outside of healthcare is in the food industry, where it has been used since the 1950s as a disinfectant applied directly to meat, fruit, and vegetables. That may seem surprising at first, but disinfection of food is a big issue in food safety, as microbial contamination is the number one enemy of the food supply. PAA leaves virtually no toxic residue after it is applied in the correct concentrations. PAA is also used to aseptically fill bottles, disinfect plumbing, and treat wastewater, because it kills bacteria with no long-term adverse environmental impacts. Peracetic Acid will likely remain to be a popular antimicrobial in the food and sanitation industries because of its efficacy, low cost, ease of application, and lack of toxic residues.
Continuous Monitoring systems should play a part in impacting these crucial dynamics in the department:
• Employee Turnover – The number one challenge in Sterile Processing is employee turnover. Employee Turnover results in approximately $40,000 in additional training costs per employee. A Continuous Monitoring system alone will not fix a department’s turnover problem, but it could play a role in showing your team you care about them.
• Motivation – If an employee feels valued, they will be more motivated to excel in their role. The saying goes, “Treat your employees like they make a difference, and they will.” If you want your team to buy into your vision for the department, make sure they know their safety is the organization’s number one priority.
• Quality – Unsafe work conditions negatively impact employee performance and overall quality. Poor quality leads to poor surgeon satisfaction and possibly even poor patient outcomes. Stay ahead of the culture of failure and make sure your team knows they are technical professionals, working with carefully maintained equipment, which is being monitored by accurate monitoring systems.
PPE (personal protective equipment) like gloves, gowns, and masks, can cost a Sterile Processing or Endoscopy department in the vicinity of $85,000-$176,000 annually. Air circulation and filtration systems, commonly used in wards of immunocompromised patients, are used to keep pathogens isolated and prevent patient exposure. These systems are estimated to cost a department around $20 a day, or anywhere from $5,000-$17,000 per year, depending on the type of filtration system and size of the hospital. For the Endoscopy department’s safety, upfront cost for one continuous monitor is $5,865 and then $1,625 per year for calibration costs, with a recommended policy of one monitor per sterilizer. When considering the costs incurred in keeping employees and patients safe across the entire organization with PPE and filtration systems, the cost of continuous monitoring in the Endoscopy department seems proportionate and comparatively small.