Safe, Effective Ethylene Oxide (EO) Sterilization
Midwest Sterilization Corporation
Doug Tropf, Regulatory Affairs Manager
Scott Holmes, Network Administrator
Ethylene Oxide (EO) sterilization is the most widely used and cost effective sterilization method available. EO is compatible with most medical devices and packaging, including heat and irradiation sensitive materials. Approximately 55% of medical products are processed with EO sterilization.
The EO sterilization process typically starts with inbound truck loads of palletized product being unloaded into the warehouse receiving area (warehouse areas are divided by physical barriers to prevent mixing of sterile and non sterile product).
Once unloaded, product is sorted and grouped according to the sterilization process needed. Some loads receive biologic indicators during non sterile set-up that will be tested after sterilization to verify product sterility. Product tracking records, prepared during non sterile set-up, are signed by operators at each phase of the sterilization process to document that loads are processed as planned. Once non-sterile set-up is completed, forklifts are used to move the productto a pre-conditioning room to be brought up to desired temperature and humidity conditions. These carefully controlled and monitored conditions promote the growth of any microbes present on the product resulting in a more effective kill in the sterilization chamber.
After pre-conditioning, the load is transferred to a sterilization chamber in which a controlled and validated cycle is ran to sterilize the load. During the cycle, EO is introduced into the sealed chamber under a vacuum and circulated in and around the product for a specified period of time. EO is then evacuated from the chamber and a series of gas washes follow to further remove the gas from the chamber and product.
The EO evacuated from the chamber is routed through gas tight pipes to the plant’s emission control system where it is scrubbed and converted to ethylene glycol. This environmentally friendly process creates a bi-product that can be utilized by other types of industry.
Following sterilization, the load is moved to a heated aeration room for the removal of any EO that has been absorbed by the product. The aeration room emissions are directed through a control device that consists of a series of beds filled with media that reduces EO concentrations to an environmentally safe level before they are released back into the atmosphere.
When the aeration phase is complete, the quality department processes the tracking paperwork, biological indicators, and computer data collected to ensure all quality parameters have been achieved prior to release of the product. The sterilized loads are stored in the sterile area of the warehouse prior to shipment. The entire EO sterilization process is carefully monitored by trained operators using computer control and monitoring equipment. Reports and printouts are generated for each phase in the sterilization process to ensure quality and safety standards are met. Sterilization process tracking records must be maintained in accordance with regulatory requirements.
EO sterilization facilities are heavily regulated, resulting in many safety oriented engineering and work practices that include ventilation systems designed to move air in a manner that reduces employee exposures to EO. Specially designed work stations that vent air away from employees during up close handling and inspection of the product is also provided. Employees removing product from sterilization chambers are required to wear breathing protection to guard against unsafe EO exposures. Both personnel and area air monitoring are routinely conducted to ensure a safe and healthful work environment.
EO sterilization’s cost effective quality performance continue to make it the sterilization method of choice for the medical product industry.