Aseptic filling sterility confidence level

There is no appropriate defined sterility confidence level which can be translated directly into acceptance criteria for broth fill contamination for BFS processes. The most commonly recognized acceptance criterion is a sterility assurance level (SAL) of 10 although modem aseptic filling techniques such as BFS can achieve a higher SAL. This should be reflected by broth fill results and acceptance criteria for this advanced technology. 

Because of the level of automation of the entire process, little human intervention is required during manufacture compared to traditional aseptic filling and it is considered an advanced aseptic filling process. It is therefore possible to achieve very high levels of sterility confidence with a properly configured BFS machine designed to fill aseptically. 

This raises a second question of how much confidence must one have to claim sterility The answer to this question, for terminally sterilized products, is that there must be no more than one chance in a million that viable contaminants survive in any one unit. This is called a sterility assurance level (SAL) of 10 . The answer for aseptically filled products is that the SAL must be as close to 10 as is technically possible, with the proviso that thedegree of protection given to the process must afford no more than one chance in a thousand of any one unit becoming contaminated. This is called a contamination rate of 10 , and unlike the SAL it relates only to the protection given to the process and not to the potential for contaminants surviving or proliferating in actual products. ... 

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