ASTM F1608 - Standard Test Method for Microbial Ranking of Porous Packaging Materials (Exposure Chamber Method):
ASTM F1608 is a test method for evaluating the microbial barrier properties of porous materials used in packaging sterile medical devices. This method is primarily designed to assess the passage of airborne bacteria through these materials, a crucial factor in maintaining the sterility of packaged devices.
The main value of the ASTM F1608 test method lies in its ability to provide quantitative data on the material's microbial barrier properties. This data can help evaluate the relative potential of a given porous material to contribute to the loss of sterility in the packaged content.
However, it is essential to remember that ASTM F1608 is not a predictive measure of a material's performance in a specific sterile packaging application. Maintaining sterility depends on several factors, including:
- Bacterial challenge: This includes the types and quantities of microorganisms the packaging is likely to encounter throughout its lifecycle. Variables such as shipping methods, shelf life, geographic location, and storage conditions can significantly influence this factor.
- Package design: Aspects such as the adhesion between materials, secondary and tertiary packaging, and the type of device inside the package play crucial roles.
- Air exchange rate and volume: This involves the changes in air that the porous package encounters during distribution and shelf life, influenced by factors such as free-air volume within the package and pressure changes from transportation, weather, or mechanical influences.
- Microstructure of the porous material: This influences the material's ability to adsorb or trap microorganisms under different airflow conditions.
ASTM F1608 provides a framework for determining the passage of airborne bacteria through porous materials, using conditions that result in detectable bacterial spore migration. A round-robin study conducted with eleven laboratories tested duplicate samples of six commercial porous materials to determine the Log Reduction Value (LRV). However, the study cautioned against comparing test data and ranking materials, especially when a small number of sample replicates are used.
Furthermore, the execution of this test method should be restricted to trained personnel due to the manipulation of microorganisms involved.