Technician in blue latex gloves is inserting sealed dental probes inside an autoclave sterilizer. Closeup horizontal photo.

Why Ethylene Oxide Matters

January 18, 2022

Prolonged exposure to ethylene oxide (EtO) can be particularly harmful to humans – causing cancer and other diseases. EtO is a flammable, colorless gas used in the production of other chemicals needed for products like antifreeze, textiles, plastics, detergents, and adhesives. It’s also used to sterilize equipment and plastic devices that can’t be sterilized with steam – like medical equipment.

Ethylene oxide in the air can come from industrial sources, including chemical manufacturers and commercial sterilizers. It can also come from other non-industrial sources such as vehicle exhaust, plants, and cigarette smoke.

The United States Environmental Protection Agency (EPA) classified EtO as a known human carcinogen in December 2016.

Then, in 2018, the National Air Toxics Assessment review identified census tracks across the U.S. with elevated cancer risks because of EtO and updated its carcinogenic risk factor which determined it to be more carcinogenic than they originally thought. However, some have raised concerns over these assessments and believe them to be flawed.

Let’s take a look back at our history with EtO.

  • 1970 – The Clean Air Act is passed. This federal law regulates air emissions. EtO is considered a “hazardous air pollutant” that the EPA regulates at chemical manufacturing plants and sterilizer facilities.
  • 1985 – EtO is listed by the National Toxicology Program as a likely human carcinogen.
  • 1994 – The National Emission Standards for Hazardous Air Pollutants (NESHAP) adopts stationary source standards for EtO.
  • 2000 – EtO is listed by the National Toxicology Program as a known human carcinogen.
  • 2006 – NESHAP conducts the first 8-year review of EtO. No rule revisions are adopted.
  • 2016 – There’s a change in Integrated Risk Information System (IRIS) Risk Values for EtO. There’s a new inhalation URF increasing lifetime inhalation risk by a factor of about 30.
  • 2018 – National Air Toxics Assessment (NATA) identifies census tracts with potentially elevated risk from EtO exposure.
  • 2020 – EPA Finalizes Amendments to the Miscellaneous Organic Chemical Manufacturing National Emission Standards for Hazardous Pollutants (MON) covering EtO emissions from tanks, vents, and equipment leaks.
  • 2021 – The EPA issues a press release announcing broadening Toxic Release Inventory (TRI) reporting on EtO to include select contract sterilizers.

The EPA is currently taking a closer look at regulations to address EtO. They’re also working to review other regulations for facilities that emit EtO. These include complex rulemaking that can take three years to complete. These rules are under review with anticipated final dates:

  • Commercial Sterilizers:  2022
  • Hospital Sterilizers:  2023
  • Group 1 Polymers and Resins (Neoprene):  2024
  • Synthetic Organic Chemicals Manufacturing Industry:  2024
  • Polyether Polyols Production:  2024
  • Chemical Manufacturing Area Sources:  2024

If your organization is concerned about keeping up with EtO regulations, reach out to one of our experts at Montrose Environmental to walk through how we can help you.

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