Lena Shahbandar, MD
11/11/2018
History of Ethylene Oxide:
Ethylene oxide has been in commercial use for approximately 90 years. It was initially used in the agricultural context to prevent Japanese beetle dispersion1. In the medical field, ethylene oxide has been used for decades as an established means to effectively sterilize heat sensitive materials. However, ethylene oxide is a highly flammable compound with carcinogenic and mutagenic properties. In order to mitigate its toxicity (documented since the mid-20thcentury), it was historically mixed with chlorofluorocarbons (CFCs) in an 88%CFC/12%EO mixture1. In the 1980’s the Clean Air Act was passed and the US EPA raised concern over ethylene oxide as an air pollutant in a Federal Register notice—the “Assessment of Ethylene Oxide as a Potentially Hazardous Air Pollutant”2. The industry standard of using CFCs was then further altered in 1989 with the passing of the Montreal Protocol, which was signed and ratified by all UN member nations, in the effort to reduce the depletion of the ozone layer. After the passage of the Montreal Protocol, sterilization with ethylene oxide was shifted to pure ethylene oxide1. While that reduced the CFC burden on the atmosphere, the use of 100% ethylene oxide in sterilization resulted in increased flammability and toxicity of the sterilant. In 2008, the International Association for Research on Cancer declared ethylene oxide (EtO) a Group 1 carcinogen3. In December 2016, the United States EPA also classified ethylene oxide as carcinogenic to humans4. Concurrent with the increased awareness of the toxicity of EtO as well as the restriction of use of CFCs, the industry has seen an emergence of alternative technologies that improve sterilization time and reduce toxicity.
Alternative sterilization options:
Until the 1990’s, ethylene oxide remained the dominant form of sterilization for temperature- sensitive materials. However, the last two decades have seen an emergence of alternative sterilization options.5 ,1 ,6 Alternatives include:
1) Peracetic acid
2) Radiation (gamma and electron beam)
3) Vapor-Phase Hydrogen Peroxide
4) Plasma (hydrogen peroxide)
5) Hydrogen peroxide and ozone
6) Nitrogen Dioxide
The following chart describes advantages and disadvantages of the sterilization methods1,7,8,9,10:
Rutala William and David Weber. “Disinfection, sterilization, and antisepsis: An overview” Am J of In Control. 44 (2016) e1-e6
“A Comparison of Gamma, E-beam, X-ray and Ethylene Oxide Technologies of the Industrial Sterilization of Medical Devices and Healthcare Products.” Gamma Industry Processing Alliance. August 31, 2017.
“Fact Sheet: Ethylene Oxide Sterilant Alternatives” Board of Public Works City of Los Angeles. 1992. “A Guide to Nitrogen Dioxide Gast Sterilisation” Medical Plastics News. 19 Jun 2012.
Harrell R et al. “Risks of Using Sterilization by Gamma Radiation: The Other Side of the Coin” Int J Med Sci 2018, Vol 15
While ethylene oxide is effective in the sterilization of plastics, and the benefits of using a single sterilant with high product compatibility makes a strong argument for the continued use of EtO, the following chart also demonstrates there are alternative sterilization methods available for almost every plastic without the added risk of ethylene oxide11:
“Plastics Sterilization Compatibility.” Industrial Specialities Mfg & IS Med Specialties.
Medical Sterilization:
Medical device and product sterilization is essential to maintain the safety and health of patients undergoing medical interventions. There are two main categories for medical sterilization—the sterilization of reusable materials and the sterilization of disposables.
Hospitals primarily sterilize reusable materials. Over the past decade, many hospitals have successfully moved away from use of ethylene oxide due to its cost, inefficiency, and toxicity. Some documented transitions in hospital settings are noted below:
1) Early implementers of alternatives: Mary Hitchcock Memorial Hospital in Lebanon, New Hampshire documented its efforts in 2002. This hospital implemented use of both peracetic acid and hydrogen peroxide plasma devices and was able to significantly reduce its ethylene oxide use12.
2) In 2008, the Kaiser Health system documented its effort to reduce their ethylene oxide sterilization burden13.
3) By 2014, St. Joseph Hospital and Medical Center in Phoenix demonstrated even further success in reduction of ethylene oxide sterilization usage. St. Joseph was able to eliminate 100% of its use of ethylene oxide by substituting it with a hydrogen peroxide sterilization system. After implementation they were able to increase the output of sterile devices by 250%14.
In many Chicago-area hospital systems, there has been a large shift away from ethylene oxide, consistent with the above-mentioned efforts. Advocate Good Samaritan and the entire Advocate system shifted away from ethylene oxide approximately a decade ago. Saint Anthony Hospital eliminated use in 2014, and Swedish Covenant Hospital terminated use in 201515.
On the other hand, in the arena of disposable sterilization, ethylene oxide remains a major player. The sterilization of disposable medical materials occurs largely at manufacturers or off- site, contract sterilization companies. In this environment, ethylene oxide is the most commonly used sterilization method (50%), followed by gamma radiation (40%), and then other less commonly used methods1. One of the challenges with shifting away from ethylene oxide has been in sterilization of products with long, small lumens. However, as demonstrated in the shift in sterilization methods used in hospitals, industry innovation and advancement can allow for safer sterilization alternatives to take hold as the dangers of ethylene oxide sterilization are recognized. Just as the Clean Air Act and the Montreal Protocol were passed to protect our environment and precipitated a burst of innovation, new policy changes to safeguard the health of our population should surely encourage a healthy shift in commercial disposable sterilization practices.
WORKS CITED
1. “A Comparison of Gamma, E-beam, X-ray and Ethylene Oxide Technologies of the IndustrialSterilization of Medical Devices and Healthcare Products.” Gamma Industry Processing Alliance.August 31, 2017.
2. “Alternative Control Technology Document—Ethylene Oxide Sterilization/Fumigation Operations” US EPA Office of Air Quality Planning and Standards, March 1989.
3. “Ethylene Oxide.” IARC monograph-100F. https://monographs.iarc.fr/wp- content/uploads/2018/06/mono100F-28.pdf
4. “Evaluation of the inhalation carcinogenicity of ethylene oxide: executive summary.”December 2016. https://cfpub.epa.gov/ncea/iris/iris_documents/documents/subst/1025_summary.pdf#named dest=woe
5. Schneider, P. Low-temperature sterilization alternatives in the 1990s. United States: N. p.,1994.
6. Schneider, P. “New technologies and trends in sterilization and disinfection.” Am Jour of Inf Control. 41 (2013) S81-S86
7. Rutala William and David Weber. “Disinfection, sterilization, and antisepsis: An overview” Am Jof In Control. 44 (2016) e1-e6
8. “Fact Sheet: Ethylene Oxide Sterilant Alternatives” Board of Public Works City of Los Angeles. 1992.
9. “A Guide to Nitrogen Dioxide Gast Sterilisation” Medical Plastics News. 19 Jun 2012.
https://www.medicalplasticsnews.com/news/technology/a-guide-to-nitrogen-dioxide-gas- sterilisation/
10. Harrell R et al. “Risks of Using Sterilization by Gamma Radiation: The Other Side of the Coin”Int J Med Sci 2018, Vol 15
Schneider, P. Low-temperature sterilization alternatives in the 1990s. United States: N. p.,
1994. Web
11. “Plastics Sterilization Compatibility.” Industrial Specialities Mfg & IS Med Specialties.
12. “Replacing Ethylene Oxide and Glutaraldehyde” Environmental Best Practices for Health CareFacilities. Nov 2002. https://noharm-uscanada.org/sites/default/files/documents- files/918/Replacing_Eth_Oxide_and_Glut.pdf
13. Brown, Janet. “Focus on sterilization and high-level disinfection in a healing environment.”Heathcare Design, Jan 2008.https://www.healthcaredesignmagazine.com/trends/architecture/focus-sterilization-and-high- level-disinfection-healing-environment/
14. Miller, Robert. “Eliminating ETO translates to improved efficiency for Phoenix Hospital”,Infection Control Today, Marc 25 2014. https://www.infectioncontroltoday.com/purchasing/eliminating-eto-translates-improved- efficiency-phoenix-hospital
15. 2014 NATA Emissions Updates (as of August 22, 2018.)
Disclaimer:
This blog post is a representation of the author's opinion. Blog posts are intended for informational purposes only and not indented to provide medical or legal advice. Individual authorship may not represent all opinions of the Stop Sterigenics community.