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Peracetic acid (PAA) is a strong oxidizing antimicrobial chemical. In healthcare, the CDC describes it as the active agent in an automated machine that chemically sterilizes immersible medical, surgical and dental instruments. It works quickly, even with organic soil present, but it is a point-of-use process with real limits.
This page describes products and general use; it is not medical advice.
Definition and scope
Peracetic acid, also called peroxyacetic acid, has the formula CH3CO3H (CAS 79-21-0) and is a strong oxidizer. Per the general chemistry reference on Wikipedia, it is made from acetic acid and hydrogen peroxide and is sold as a mixture with both, which keeps it stable. This page covers what the CDC says about it as a sterilant for reusable instruments in clinics and labs. Industrial, food-processing and water-treatment uses are outside its scope.
The CDC calls peracetic acid “a highly biocidal oxidizer that maintains its efficacy in the presence of organic soil.” Its mode of action is “thought to function as other oxidizing agents, i.e., it denatures proteins, disrupts cell wall permeability.”
How it is used in practice
The CDC describes an automated system. A single-dose container holds 35% peracetic acid plus an anticorrosive agent. The concentrate is diluted to 0.2% with filtered water at about 50 °C and pumped through the endoscope channels for 12 minutes. A chemical test strip can detect levels above 1500 ppm. The solution is discarded via the sewer and the instrument is rinsed four times with filtered water. Manufacturers suggest biological monitors (Geobacillus stearothermophilus spore strips).
That is a description of the product category, not operating guidance. Always follow the instructions for use of the specific device and the instrument maker.
What the CDC reports on microbial kill levels
| Target | Concentration and time reported by the CDC |
|---|---|
| Gram-positive and gram-negative bacteria, fungi, yeasts | Inactivated in under 5 minutes at under 100 ppm |
| Same organisms with organic matter present | 200-500 ppm required |
| Viruses | Wide dosage range, 12-2250 ppm |
| Bacterial spores in suspension | 15 seconds to 30 minutes at 500-10,000 ppm |
These are laboratory suspension figures from the CDC’s review, not performance claims for any product, and they are not a substitute for a manufacturer’s validated cycle.
Related concepts
Peracetic acid sterilization is one of the low-temperature options discussed in low-temperature sterilization method selection. Where it sits between sterilization and disinfection is covered in high-level disinfection and the Spaulding classification, and proof that a process works is covered in sterilization validation. For the wider family of chemical agents see types of disinfectants, for the instruments this process is built around see what an endoscope is, and for how sterility is expressed as a probability see sterility assurance level.
The CDC lists “Peracetic Acid/Hydrogen Peroxide” as a separate row from peracetic acid alone. It names different concerns for it: materials compatibility concerns (lead, brass, copper, zinc), limited clinical experience, and potential for eye and skin damage. Treat the two as different products.
Where it matters for labs, clinics and supply decisions
The CDC’s page on advantages and disadvantages of chemical sterilization (dated December 19, 2023, citing the 2008 guideline) gives the trade-offs side by side.
| CDC-listed advantages | CDC-listed disadvantages |
|---|---|
| Rapid cycle time (30-45 minutes) | Used for immersible instruments only |
| Low-temperature (50-55 °C) liquid immersion | Point-of-use system, no sterile storage |
| By-products are acetic acid, oxygen and water | One scope or a small number of instruments per cycle |
| Fully automated; single-use system removes concentration testing | Potential material incompatibility (for example, anodized aluminum becomes dull) |
| Does not coagulate blood or fix tissue to surfaces | Biological indicator may not be suitable for routine monitoring |
| Rapidly sporicidal | More expensive than high-level disinfection; concentrated solution can seriously damage eyes and skin |
Checks that follow directly from the CDC text, for anyone weighing a reprocessing system:
- Compatibility listing. The CDC notes that Olympus America has not listed this system as compatible for its bronchoscopes and GI endoscopes, so the instrument maker’s compatibility statement matters.
- Connectors. Lumened devices need the correct channel connector; inappropriate connectors have been tied to bronchoscopy-related infections.
- Water quality. The CDC records concern that filtered water may be inadequate to maintain sterility.
- Materials. Anodized aluminum is the CDC’s example of a material that can be affected.
Common misunderstandings
- It is not the same as a vinegar and peroxide mixture. Commercial peracetic acid is a controlled chemical product; the CDC lists serious eye and skin damage on contact with the concentrated solution.
- Sterilization is not stored sterility. The CDC lists “no sterile storage” as a disadvantage, because it is a point-of-use process.
- It does not suit every instrument. The process is for immersible instruments only.
- PAA alone and PAA with hydrogen peroxide are different rows. Their advantages and disadvantages are not interchangeable.
FAQ
What is peracetic acid used for in healthcare?
The CDC describes an automated machine that uses it to chemically sterilize immersible medical, surgical and dental instruments, with endoscopes as the main example.
Is peracetic acid the same as peracetic acid with hydrogen peroxide?
No. The CDC lists them as separate rows with different advantages and disadvantages, including materials compatibility concerns (lead, brass, copper, zinc) for the peroxide combination.
Does peracetic acid sterilization leave instruments sterile in storage?
No. The CDC lists it as a point-of-use system with no sterile storage.
Does peracetic acid work when organic soil is present?
The CDC describes it as maintaining its efficacy in the presence of organic soil, although its figures show a higher concentration range (200-500 ppm) is needed against bacteria, fungi and yeasts when organic matter is present.
Can any instrument be processed this way?
No. The CDC lists immersible instruments only, one scope or a small number of instruments per cycle, and potential material incompatibility, so the instrument maker’s compatibility statement matters.
Sources
- CDC, Peracetic Acid Sterilization, checked 2026-10-29.
- CDC, Advantages and Disadvantages of Chemical Sterilization, page dated December 19, 2023, checked 2026-10-29.
- Wikipedia, Peracetic acid (chemical formula and composition only), checked 2026-10-29.
