An Insight into the Process of Sterilization by Ethylene Oxide

Ethylene oxide is used in many products and industries, including household cleaners, disinfectants, detergents, laundry soaps, antifreeze and automotive fluids. It also is used in the manufacturing of medical devices and personal protective equipment.

Sterilization by ethylene oxide is an essential part of the modern healthcare industry. It helps prevent infection and disease, manufactures medications that are safer to deliver, and ensures that medical equipment is not damaged during transport or use.

Ethylene oxide is widely used in the production of chemicals and products. It also is a valuable component of the medical device sterilization process, sterilizing devices such as catheters, needles, surgical tools and implants that are needed to help prevent disease and infection.

Sterilization by Ethylene Oxide is a common sterilization method used to chemically destroy microorganisms on medical devices and products. It is an effective and cost-effective alternative to traditional dry heat or steam sterilization methods, but it does have its limitations. It may cause toxic residuals that can be harmful to human health.

EO can sterilize a wide range of materials, making it an attractive option for many medical devices and products. It is an alkylating agent, meaning it disrupts cellular metabolism and reproductive processes of microorganisms and has a high penetrating power for reaching surfaces.

EO Sterilization Process

EO Sterilization Process

The EO sterilization process involves a series of steps to ensure a safe and efficient procedure. This includes preconditioning, the introduction of ethylene oxide, and post-sterilization processing.

Preconditioning: Before loading items into the sterilization chamber, they are pre-humidified to a specific level of relative humidity by using steam injections (or similar). This process helps replenish the moisture that was lost during the evacuation phase and also allows the products to aerate more easily when exposed to the ethylene oxide gas in the sterilization chamber.

Exposure Phase: During this phase, the products are exposed to ethylene oxide in a vacuumed and humidified chamber for a period of time that is determined by the specialized cycle design scientist based on product type, load configuration, and desired sterility assurance level. This exposure time is typically 3-6 hours or longer depending on the material and the amount of ethylene oxide used in the cycle.

Sterile Removal: After the EO exposure phase, all of the ethylene oxides that remains within the chamber is removed by performing a series of post-vacuums followed by nitrogen backfill washes. This process can take anywhere from 1 to 6 hours, and it is performed multiple times to ensure that all of the ethylene oxide has been purged from the sterilizer and products.

Nitrogen Dilution: After the sterile removal phase, the ethylene oxide is again introduced into the chamber but this time with the addition of nitrogen to further aid in air removal from the chamber and product. This is done to further reduce residuals and increase safety in the EO sterilization process.

Air Purge: The ethylene oxide vapour is then slowly and safely purged from the chamber, and the products are allowed to off-gas during this time as well. The ethylene oxide concentration in the chamber must fall below the flammable limit for EO.

EO Residual Testing: Any product sterilized with ethylene oxide that comes in physical contact with patients must undergo a series of ethylene oxide residual tests to determine if they meet strict EO residue limits to keep people safe. These EO residuals can include ethylene oxide, ethylene chlorohydrin, and ethylene glycol.

These ethylene oxide residues are toxic and can be carcinogenic to humans at certain levels. Therefore, all ethylene oxide-sterilized medical devices and products must be tested to determine if they meet current EO residual limits set by the FDA. This testing is called simulated use or exhaustive extraction and can be done by either a laboratory or an experienced contract testing organization.