Wednesday, January 12, 2011

Peracetic Acid Uses, Health Risks & Workplace Guidelines

Peracetic or peroxyacetic acid (PAA) is a strong oxidizing agent used for high level disinfection and sterilization at low temperatures. It is water soluble, and leaves no solid residue after rinsing and the end products are only water, oxygen and acetic acid (vinegar), making PAA a very environmentally friendly compound.

In healthcare, the demand for faster turnaround time of heat sensitive reprocessed multiple-use medical devices led to the development of PAA liquid sterilization, given ethylene oxide’s longer required aeration time at the end of the sterilization cycle to vent the gas. In addition, the food packaging and waste water treatment industries have adopted PAA as a preferred disinfectant and sterilant wash because of its environmental properties.

Health Risks of PAA Exposure

As an antimicrobial agent, PAA is broadly effective against a wide range of microorganisms; it disrupts bonds in proteins and enzymes and interferes with cell membrane transportation through the rupture of cell walls, oxidizing essential enzymes and impairing vital biochemical pathways.

The properties of PAA that make it an efficient sterilant and environmentally friendly make it potentially dangerous to any employees exposed to it in the workplace. Unfortunately the health risks to workers from PAA exposure are not known by many employers. Hospitals, food handling and processing industries commonly use PAA, in concentrations that can be harmful to workers if they are exposed.

Specifically, the National Institute for Occupational Safety and Health (NIOSH) Registry of Toxic Effects of Chemical Substances identifies PAA as a primary irritant, known tumorigen and mutagen.

The New Jersey Department of Health and Senior Services Occupational Health Service released a study on the the health effects of PAA exposure. The study also found that PAA is very irritating to the skin, eyes, nose, throat, and lungs, with the potential for causing permanent scarring of the skin, cornea, and throat. Higher exposures in the short term can also cause pulmonary edema as well as liver and kidney effects.
PAA Workplace Guidelines

While there are no Occupational Saftey and Health Administration (OSHA )regulations specifically for PAA - most OSHA PELS have not been updated since their initial adoption in 1972 - the Environmental Protection Agency (EPA) has issued Acute Exposure Guideline Levels (AEGLs) for PAA, specifically:

AEGL-3 (death/permanent incapacity) 1.3 ppm: the threshold above which mortality and/or irreversible effects could be observed for an exposure of up to 60 minutes. AEGL-3 is analogous to the NIOSH Immediately Dangerous to Life or Health (IDLH) chemical listing concentrations and documentation values, which are 75 ppm for hydrogen peroxide and 800 ppm for ethylene oxide.
AEGL-2 (disability) 0.51 ppm: the threshold level above which intense lacrimation, extreme nose discomfort and transient incapacitation (inability of self protection but without residual consequences) could be observed for an exposure of up to 60 minutes.

AEGL-1 (discomfort) 0.17 ppm: the level above which discomfort could be observed for an exposure of up to 8 hours per day. AEGL is analogous to the OSHA PEL (1 ppm for both hydrogen and ethylene oxide, calculated as an 8 hour time weighted average. See OSHA Standard 1910.1000, Table Z1 Limits for Hydrogen Air Contaminants and OSHA Standard 1910.1047 for Ethylene Air Contaminants.

PAA Continuous Monitoring Solution

Designed specifically for occupational safety, the ChemDAQ PAA monitoring system gives immediate indication of PAA concentration in the work area so that workers can protect themselves from acute and chronic exposure. The Steri-Trac® area monitor has alarm limits and a real time display of PAA concentrations in ppm to provide safety from acute exposure. The DAQ® Central Monitoring System tracks EPA AEGL-1 and AEGL-2 with alerts to provide a level of safety from chronic exposure to PAA.

The continuous monitoring of PAA can help protect employees from the acute and chronic health affects by reporting the toxic concentrations in real time and providing alarms for proactive protection. Many employers whose workers have experienced symptoms of exposure and expressed concern are looking for solutions. A continuous monitoring system along with a comprehensive education program and safe work practices are the best ways to assure worker safety and maximize productivity.

For more information, check out the ChemDAQ Steri-Trac Peracetic Acid Area Monitor.


  1. Is peracetic acid harmful to eyes. My vision has become blurry since working wth glut and peracetic acid for last 4 year

  2. Does the combination of white vinegar at 5% and hydrogen peroxide at 3%, readily available in a grocery store, become peracetic acid? And can this specific combination ever cause the kind of harm to humans in the home as is decried here?

    1. Thanks for the Question. Yes, a mixture of 5% acetic acid (vinegar) and 3% hydrogen peroxide will form peracetic acid. The concentration of PAA can be calculated from the equilibrium constant and the risk of exposure estimated.

      In normal home use, the quantities used are very small and so the risk of exposure is minor. However, if the same mixture were used on a commercial scale, such as food processing operation spraying the mixture all day, then occupational exposure may be significant.

      Many chemicals commonly used in the home have stringent occupational exposure levels. Very few people are concerned about bleach in the home, but OSHA has ceiling PEL 1 ppm.

  3. What amount of dilution and neutralization is needed to make peracetic acid acceptable to put into a sewage system?

    1. I am sorry I don't know the answer to this question. The amount of dilution needed is normally determined by the local water authority. I recommend contacting them and I am sure they can give you an answer.