What a sterility assurance level of 10^-6 means

CRCST practice question · Sterilization Process

What does a sterility assurance level (SAL) of 10^-6 mean?

  • A. One million microorganisms remain on each item after processing
  • B. The cycle kills microorganisms in one-millionth of a second
  • C. Six spore strips must be tested in every load
  • D. There is no more than a one-in-a-million chance that a viable microorganism remains on an item

Answer

D. There is no more than a one-in-a-million chance that a viable microorganism remains on an item

An SAL of 10^-6 is the probability standard for terminal sterilization of medical devices: at most a one-in-a-million chance of a surviving microorganism. It is a statistical measure, not a count of survivors or a testing requirement.

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