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Ethylene Oxide Sterilization

Ethylene Oxide (EO or EtO) is a simple chemical compound that is commonly used for gaseous sterilization of disposable healthcare products. A wide variety of materials and components commonly used in the manufacture of these products may be sterilized with ethylene oxide in their final breathable packaging configuration.

History of ethylene oxide

  • 1859 – Ethylene oxide is discovered
  • 1920s/1930s – EO is used for fumigation
  • 1940s – EO is developed as a sterilant by the U.S. military
  • Late 1950s – The McDonald process is patented for medical devices
  • 1998 – EOExpress® technology introduced

How does ethylene oxide work?

EO sterilization is a chemical process consisting of four primary variables: gas concentration, humidity, temperature and time. Ethylene oxide is an alkylating agent that disrupts the DNA of microorganisms, which prevents them from reproducing. EO sterilization assures that a safe and sterile product will be delivered to the market each and every time.

What is ethylene oxide used for?

The EO process is ideal for:
  • Custom procedure kits
  • Cellulose and plastic products that may exhibit discoloration with irradiation
  • Devices manufactured from materials whose physical properties degrade with heat or irradiation
  • Various materials not compatible with other methods of sterilization, such as tissue and collagen

What is a typical ethylene oxide processing cycle?

The EO sterilization process may take place within a traditional cycle or through our exclusive EOExpress® expedited processing cycle. Both options consist of three processing phases:

  • Pre-conditioning: Used to preheat and humidify product loads to predefined conditions. This will assure a repeatable sterilization process regardless of pre-processing load storage conditions
  • Sterilization: Performed using process phases specifically designed to provide the required level of ethylene oxide exposure to assure sterility for a device or family of devices
  • Aeration: Used to accelerate out gassing of exposed product loads and to contain and eliminate residual ethylene oxide emissions

Traditional Ethylene Oxide Processing

  • Biological indicators are placed into the sterilization load, and the load is placed into a preconditioning room
  • The product is then moved into the sterilization chamber where it is treated with EO gas
  • Following exposure, the product is transferred into an aeration cell for dissipation of the EO
  • Biological indicators are removed from the product and tested
  • Product is shipped to the Customer while still in quarantine
  • Product is released once the biological indicators have completed testing and the EO residual levels are acceptable

EOExpress® Expedited Processing

  • Product is loaded into the sterilization chamber, where it is exposed to all three phases of the sterilization process (pre-conditioning, sterilization and aeration)
  • This process uses parametric release, which eliminates the labor and time of post-process sterility testing
  • In-chamber aeration prevents products from having to be held for EO residual dissipation
  • Products can be processed and released to market within one day

Click here to read our EO TechTips and learn more about the ethylene oxide sterilization process

Spordex BIs

STERIS Spordex® Biological Indicators
Order online at steris.com

Spordex Bacillus atropheus spore strips with a 106
population used for ethylene oxide or dry heat cycles
Available in quantities of 100 or 500