Permissible Exposure Limits for Sterilant Gases

If you use Ethylene Oxide (EtO), Hydrogen Peroxide (H₂O₂), or Peracetic Acid (PAA) at your facility, it’s important to know and understand the industry standards set forth for the safe administration and use of these sterilant chemicals to protect both your business and your workers.

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Occupational Exposure Limits

Several government agencies and industry associations have set limitation guidelines for workers exposed to EtO, H₂O₂, and PAA. These guidelines are enforced to ensure workers who are exposed to high concentrations of these sterilant chemicals do not develop serious health problems, ranging from minor irritations to serious health concerns.

In the USA, the Occupational Safety and Health Administration (OSHA) has promulgated Permissible Exposure Limits (PELs) for several hundred chemicals (29 CFR 1910.1000) and some states also have their own PELs. These PELs are legally enforceable exposure limits. In addition, government agencies such a the National Institute of Occupational Safety and Health (NIOSH) has issued its recommended exposure limits and the American Conference of Governmental and Industrial Hygiene (ACGIH) has issued its Threshold Limit Values (TLVs).

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How Chemical Monitoring Can Help

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Permissible Exposure Limits

Note 1: For hydrogen peroxide Short Term Exposure Limits: The 15-minute Time Weighted Average (TWA) is 2 ppm in the UK and Hawaii, 3 ppm in Washington, and typically2 ppm or 3 ppm in Canada based upon province.

Note 2: OSHA uses the term ”Excursion Limit” to describe the STEL for EtO (29 CFR 1910.1047)

Note 3. The NIOSH REL for ethylene oxide is < 0.1 ppm 8 hr TWA, and for the short term exposure a ceiling of 5 ppm (max 10 min/day).


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Ethylene Oxide

EtO is a sterilant chemical used in hospitals and the medical device manufacturing industry. EtO is a very effective sterilant, with excellent material compatibility, but it is also a known carcinogen, mutagen and teratogen and so exposure can cause serious health effects. It’s also a colorless chemical that is highly flammable and reactive at room temperature. 

Hydrogen Peroxide

H₂O₂ is a sterilant chemical used in hospitals and aseptic packaging facilities. H​O is a strong oxidant. Contact with the liquid can cause chemical burns, and exposure to the vapor can cause damage to the eyes and the respiratory system. H​O is environmentally friendly because its high reactivity results in a short residence time if it is released into the environment and the benign decomposition products are only oxygen and water.

Peracetic Acid

PAA is a widely-used disinfectant chemical in hospitals and throughout the food processing industry. PAA is a stronger oxidizing agent than even H​O. Contact to the chemical can cause chemical burns and exposure to the vapor can cause damage to the eyes and respiratory system. PAA solution is a colorless liquid with a strong vinegar-like odor. Like H​O, PAA is environmentally friendly because it rapidly breaks down to form benign products, namely oxygen and acetic acid, so PAA is safe for direct food contact.

How is Workforce Safety Mandated?

The Occupational Safety and Health Administration (OSHA) is authorized by the 1970 Occupational Safety and Health Act to regulate, monitor and inspect workplaces. In many cases, these inspections can be unannounced and can cover any place of employment – from structure and machines to equipment and materials. The National Institute for Occupational Safety & Health (NIOSH) has also closely examined the effects of overexposure from EtO, H₂O₂, and PAA and set forth permissible exposure limits for safe and effective use within the workplace.

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