STERIS AST Research Highlights Considerations for ISO 11137 Dose Validation

STERIS Applied Sterilization Technologies (AST) is pleased to announce newly published research examining the effectiveness of industrial gamma and electron beam (E-beam) irradiation in inactivating Bacillus pumilus spores under varying levels of water availability. 

The study, conducted and authored by STERIS TechTeam℠ Professionals Brian McEvoy, Pierre Reppert, Katharina Sturm-Lüdtke, Bianka Ulbricht, Martin Meltke, and Ana Maksimovic, was published in Radiation Physics and Chemistry.

In alignment with previous published research, studies on the comparative effectiveness of X-rays, gamma rays and electron beams to inactivate microorganisms at different dose rates in industrial sterilization of medical devices, the research found that gamma and E-beam irradiation were equally effective in inactivating dry B. pumilus spores, supporting the transfer of validated sterilization doses between industrial radiation sources when liquid water is not present.

This research demonstrated that spore resistance increased with water availability. E-beam was demonstrated to provide more effective inactivation of spores in the presence of liquid water. 

Speaking about the research, Dr. Brian McEvoy, Chief Technology Officer at STERIS AST, reflected: “As a follow-up to our previous published research work examining the effectiveness of radiation technologies with differing dose rates at inactivating dry spores, this research using similar methodology examined the effect of liquid water.  Gamma and E-beam were chosen as radiation technologies of differing dose rates. As expected, a change of spore resistance was observed and a variance in the inactivation kinetic from each technology was observed with E-beam being demonstrated as most effective. The most important aspect of these findings is the need to consider the impact of liquid water on both the initial validation and during transfer from one technology to another. It is our hope that such research helps inform important decision making and approach during validation in accordance with ISO 11137.”    

These findings provide important considerations for dose qualification strategies outlined in ISO 11137, particularly for products where moisture may influence microbial resistance. The research further strengthens industry understanding of radiation sterilization and supports the development of robust, science-based validation approaches.

The findings provide important considerations for manufacturers using radiation sterilization technologies and reinforce the importance of understanding how product definition and condition may influence dose validation strategies.

Through scientific research and technical collaboration, STERIS AST continues to support the advancement of sterilization science and industry best practices.

Access the research article through Science Direct here.