Ethylene oxide (EO) is a highly effective sterilant, which offers many advantages. However, due to its toxic nature, it has been classified as carcinogen by the U.S. Environmental Protection Agency (EPA). Due to EO’s carcinogenic nature and emissions from sterilization centers, some sterilization facilities have been shut down. This article discusses challenges faced by EO sterilization.
1. What lead to this?
In 2019, Illinois EPA sealed Sterigenics facility in Willowbrook, Illinois and temporary closures of four EO facilities in Georgia. The decision was taken due to hazardous impacts of high emissions from these facilities on the surrounding area. However, only sterilization facilities are not to be held responsible for these emissions. EO in the air can be sourced from car exhaust, cigarette smoke, manufacturing units, plant decay, and so on.
EO is majorly used for medical devices sterilization. Around 20 billion devices in the U.S. are sterilized using EO. Because of the ongoing closure of sterilization facilities, there is fear of shortage of critical medical devices and supplies. A shortage on medical supplies is an undesirable situation in itself, however, the prevailing pandemic exacerbates the concern. Even though the temporary closed facilities in Georgia have reopened, but Willowbrook facility is sealed causing strain on other sterilization facilities.
2. Challenges with EO Alternatives
Some medical devices cannot withstand high temperatures, greater than 100°C, of moist heat sterilization. EO offers a safe low temperature sterilization process, using less than 55°C to sterilize single-use thermolabile plastic medical devices.
The reason EO alternatives cannot be applied to most of the plastics is their non-compatibility with modalities such as radiation processes, including gamma, e-beam and X-ray; due to their cross-linking and chain scission in polymers.
These processes can lead to weakening of medical devices and other undesirable changes like crack, craze, or discoloring. Moreover, EO penertrates into the hardest surfaces to sterilize devices thoroughly. Whereas, alternative sterilization processes such as nitrogen dioxide, vaporized hydrogen peroxide, vaporized peracetic acid and super critical CO2 do not offer such thorough sterilization. Virtually, none of these alternative methods can sterilize on as massive scale as EO does.
3. Changes to EO Processes
Although some niche alternatives can be used, but it is more viable to change the existing EO processes for lowering the amount of EO emission. Some companies are retorting to validation processes, using overkill approach. Bacillus atrophaeus spores is the universally recognized MRO (Most Resistant Organism) for EO sterilization. A validation practice uses high concentrations of EO to kill this biological challenge, far bigger hazard than the naturally occurring bioburden. Using a PCD, to indicate the resistance of a product, for determining whether or not to use it, the resistance of bioburden is assessed.
4. The Future of EO
EO with changes can offer a sustainable process of sterilization. By controlling concentrations and reducing EO emissions, it could be made a practical solution for cleaning medical devices. Moreover, this will also help in lowering the residual levels on product, hence helping hedge against future potential changes to the ISO 10993-7 standard.
The changed and new optimized cycles can be shorter, with lower gas concentration. Anything that compromises a sterilant’s ability to penetrate through the packaging should be assessed. Breathable material may help with sterilant penetration, and efficient outgassing if the product design needs to incorporate gas pathways. Looking at the complete picture of packaging, product, and process, EO can be revamped.
The EO process parameters by Dynatec labs are specific for products packaged in a sterile wrapped peel pouch. We carry out the EO sterilization and Clean Room Certification according the changed requirements of EPA. The products and packaging tolerate the EO process better than an autoclave or radiation sterilization process. To know more about EO sterilization, get in touch with our experts not.