The Impact of Ethylene Oxide Sterilization on Elastomers: Insights and Implications

Elastomers, particularly silicone-based materials used in medical devices, undergo various sterilization methods to ensure their safety and efficacy. Ethylene oxide (ETO) sterilization is a common technique due to its effectiveness in sterilizing materials that are sensitive to heat or moisture. This blog explores how ETO sterilization affects the physical properties of elastomers, with a focus on silicone rubbers, and the implications for their use in medical applications.

Ethylene Oxide Sterilization: A Brief Overview

ETO sterilization involves exposing products to ethylene oxide gas under controlled conditions to eliminate microbial life. It's favored for materials that can't withstand the heat of steam sterilization or might be degraded by radiation. The process requires careful consideration of parameters like gas concentration, humidity, temperature, and exposure time to ensure thorough sterilization without compromising the material's integrity.

Effects on Elastomers

Elastomers react differently to Ethylene Oxide (ETO) sterilization, each with its unique advantages and drawbacks. For instance, silicone maintains excellent stability and minimal property changes post-ETO sterilization, making it ideal for medical devices requiring flexibility and durability. However, it can be more expensive compared to other materials.

Silicones are prized for their flexibility, durability, and resistance to extreme temperatures and environments. When subjected to ETO sterilization, studies have shown that the mechanical properties of some elastomers can be affected, but for silicone rubbers, the exposure to ETO gas has been observed to cause minimal to no significant change in their tensile strength, elongation at break, or hardness. This resilience makes silicone a preferred material for medical devices requiring repeated sterilization.

However, the response to ETO sterilization can vary based on the elastomer's formulation and curing process. Platinum-cured silicones, for example, have been reported to maintain their properties better than peroxide-cured ones post-ETO sterilization. This difference is attributed to the curing agents and cross-linking mechanisms involved in their production.

Nitrile rubber offers good resistance to a wide range of chemicals and performs well in ETO sterilization, but it may not provide the same level of temperature resistance as silicone. Nitrile is also not typically used for medical applications.

EPDM (ethylene propylene diene monomer rubber) is another option, known for its weather resistance and suitability for outdoor applications. Though it withstands ETO sterilization, its application in medical devices is limited by its compatibility with fats, oils, and hydrocarbons.

Each elastomer's reaction to ETO sterilization involves a balance between maintaining material integrity and ensuring complete sterilization. The choice of elastomer depends on the specific requirements of the medical device, including chemical compatibility, temperature resistance, and physical properties.

Safety Considerations

While ETO effectively sterilizes without significant degradation to elastomers, it poses safety concerns due to its toxic and carcinogenic nature. Proper aeration post-sterilization is crucial to remove any residual gas from the material. The industry adheres to strict guidelines to ensure that the levels of residual ETO fall within safe limits, protecting both patients and healthcare providers.

Conclusion

ETO sterilization remains a viable option for elastomers used in medical devices, offering effective sterilization without compromising material integrity. The selection between elastomers, particularly the choice of curing method, should consider the material's response to ETO exposure. Ongoing research and adherence to safety protocols ensure that ETO sterilization continues to be a safe, effective method for medical device sterilization.

Incorporating the latest findings and ongoing research, manufacturers can make informed decisions regarding material selection, sterilization methods, and process optimization to meet stringent regulatory requirements and deliver high-quality products to the market.

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Sources:

1. Gautriaud, E., Stafford, K. T., Adamchuk, J., Simon, M. W., & Ou, D. L. (2024, January 31). Effect of sterilization on the mechanical properties of silicone rubbers. https://www.bioprocessintl.com/monoclonal-antibodies/effect-of-sterilization-on-the-mechanical-properties-of-silicone-rubbers
   
   
2. Hosting. (2020, May 7). Silicone sterilization. TBL Plastics. https://tblplastics.com/sterilize-platinum-peroxide-cured-silicone/
   
   
3. Chen, Y. Y. (1970). Ethylene oxide penetration of the SiliconerCoating used as a lubricant on disposable syringe RubberPlunger tips and hypodermic needles. Journal of Pharmaceutical Sciences, 59(5), 717–718. https://doi.org/10.1002/jps.2600590534
   
   
4. Choosing the best method for sterilizing medical device silicones. (2022, September 1). Medical Product Outsourcing. https://www.mpo-mag.com/issues/2022-09-01/view_columns/choosing-the-best-method-for-sterilizing-medical-device-silicones/
   
   
5. “Methods Used to Sterilize Silicone Based Medical Devices.” Methods Used to Sterilize Silicone Based Medical Devices, Polymer Systems Technology Limited, www.silicone-polymers.co.uk/pdfMaster/Methods Used to Sterilize Silicone Based Medical Devices.pdf. Accessed 7 Mar. 2024.