Chlorine Dioxide: An Emerging Alternative to EtO

Due to FDA’s sterilization innovation challenge and the EPA’s new restrictions on ethylene oxide (EtO) emissions, there has been heightened attention across the healthcare industry to find and broadly adopt alternative sterilization modalities on an accelerated timeline. A select few alternatives seem to be rising to the top, including chlorine dioxide gas (ClO2). While ClO2 has been used as a sterilant in various industries for years, including healthcare, it’s use in healthcare has been minimal compared to EtO and there is an opportunity for industry to better understand this modality. I recently discussed this technology with Emily Lorcheim, Project Manager at ClorDiSys Solutions, Inc, a ClO2 provider with over 20 years of experience servicing the healthcare segment. Emily provided me with a lesson in history and basic ClO2 gas properties, as well as the benefits and potential watchouts when considering ClO2 for medical device sterilization.

The Basics: 

ClO2 has been used as a gas sterilizing agent since the 80’s and is used for treating drinking water and food products. It is generally recognized as safe by the EPA, and ClorDiSys’ gas generation specifically is an EPA Registered Sterilant. Sterilization occurs in a chamber (available in a variety of sizes to support individual sterile barrier systems or multiple pallets), which can be outsourced for contract sterilization or brought in-house for sterilization on site.  

Similar to EtO, ClO2 is a true gas, which means it has excellent distribution and penetration. But unlike EtO, ClO2 takes this form at room temperature, which is an advantage for sensitive devices (like electronics or cold chain products) that are not compatible with the elevated temperature that occurs during an EtO cycle. ClO2 is non-carcinogenic, non-flammable, and non-explosive at the concentrations for sterilization. It is yellow-green in color and can be monitored with a photometric device in real time for controlled release within the chamber. It is also water soluble, providing the ability to penetrate water, which not all sterilants can do. 

Benefits: 

• True gas = excellent penetration, including devices with complex geometries 

• Fast cycle times (~4-8 hours from pre-conditioning to final aeration, all within the chamber) 

• Sterilization occurs at room temperature, making it compatible with products such as auto-injectors, pre-filled syringes, and electronic and battery-operated devices 

• Due to the gas properties and fast cycle, residuals are typically below detectable levels on products and packaging; ClO2 does not continue to “degas” and sterilized packages and products can be handled right away 

• Compatible with many device and packaging materials, including stainless steel, anodized aluminum, plastics, cellulosic materials, gasket materials, and electronics 

• Sterilization can be contracted out, or chambers can be purchased to sterilize packaged products in-house; this is more accessible to start-ups and small businesses that struggle with EtO timelines and volume demands, but chambers also range in size, including those than can accommodate multiple pallets 

Considerations: 

• While ClO2 is recognized by the FDA and used commercially today to sterilize medical devices and follows ISO 14937:2009 like other novel sterilization modalities, there is no specific industry standard for it like there is for EtO so adoption may be a lift from a regulatory perspective (BUT, industry working groups are working on this!) 

• ClO2 exposure may cause yellowing on polycarbonate and silicone substrates, depending on material grade or blend of chemicals incorporated 

• While large multi-pallet chambers are available, EtO or other radiation modalities are currently set up to better handle particularly high volumes (~50% of devices in industry today use EtO… ClO2 is not yet scaled to meet that type of demand) 

• Products such as paper drapes and gowns are more compatible with radiation modalities, due to absorption 

As industry continues to seek EtO alternatives, it will be critical to understand the ins and outs of device and packaging material compatibility, scalability, logistical and financial implications, and environmental impact. There won’t be one solution that solves the sterilization innovation challenge, but ClO2 will certainly be one modality to pay close attention to and consider for near future testing. You can learn more about ClorDiSys and their sterilization technology here!