Sterility assurance level (SAL)

The probability that a single unit is non-sterile after sterilization, expressed as a power of ten. For terminally sterilized products the usual target is 10⁻⁶, one chance in a million. The value follows from the validated lethality of the sterilization cycle and the bioburden before sterilization. Aseptically processed products have no comparable numeric value; their assurance rests on process design, environmental control and media fills. Japanese documents use SAL as often as the Japanese term.