Peracetic acid (PAA) can burn skin, irritate eyes and lungs, and cause respiratory symptoms if exposed to high concentrations, but it breaks down quickly into harmless by‑products.
What is peracetic acid?
PAA is an organic peroxyacid formed when acetic acid reacts with hydrogen peroxide. It is clear, has a sharp odor, and oxidises microbes rapidly.
Where is it used?
Food processors use low‑concentration PAA (≤0.02%) to wash produce. Hospitals employ it in sterilising surgical instruments and endoscope reprocessors, often at 0.2–0.5% during cycles. Wastewater plants add it to effluent to kill pathogens before discharge.
Health effects of exposure
Contact with undiluted PAA can cause second‑degree skin burns. Even dilute solutions (≈0.2%) irritate skin, eyes and the respiratory tract. Inhalation above 0.5 ppm is a respiratory hazard; chronic exposure may lead to asthma‑like symptoms.
Why rapid breakdown matters
After use, PAA degrades to acetic acid, water and oxygen within 20–30 minutes in water and even faster under sunlight. This limits long‑term environmental persistence, but vapors can linger in poorly ventilated spaces.
Safety and monitoring
There is no federal OSHA permissible exposure limit. ACGIH recommends an 8‑hour time‑weighted average of 0.4 ppm. Monitoring is difficult because PAA degrades in sampling tubes; portable monitors are expensive.
Comparing disinfectants
PAA is stronger and faster than bleach, quaternary ammonium compounds and hydrogen peroxide, and leaves no toxic chlorinated residues. However, it is more volatile; a spill can saturate a room’s air quickly, making ventilation and PPE essential.
Environmental impact
In water, PAA breaks down quickly, but high concentrations can be toxic to fish. Typical wastewater limits cap PAA at about 0.5 ppm to protect aquatic life.