Sterility
Assurance Level
The
probability of having a non-sterile product
OR
the
probability of an organism surviving the process
Terminal
Sterilization: 10 –6
Aseptic
process: 10 -3
Determination
of SAL
D
– value & Z – value – Organism performance
Temperature,
Chemical Concentration, Relative humidity, Pressure, Fo – You must know the exact
physical conditions to which the spores have been exposed
Population
– you must know how many organisms are present
Calculation
of SAL
Known
BI population
Calculate
Spore Log Reduction
SLR
= Log of BI population + 2 + Log of desired SAL
Example
BI
= 1 x 106 population
log of 106 = 6
To
achieve 0 “+” BI’s in a set of 20 units from
one spore/BI requires an additional 2
Log
reduction
SAL
desired 10-6
log
of 10-6 = 6
therefore
6 + 2 + 6 = 14 SLR
Minimum
Sterility Assurance Level
SAL
10-6 = D121 value x 14 SLR = “X” minutes process exposure
NOTE:
This is more accurate if F0 is used instead of simply minutes of
exposure
Calculation
of SAL
Known
D-value, population and the process F0 value:
A)
SLR =
F0
D-value
B) SAL = 10-x
C) X = SLR – (log of population) – 2
Example
Known Unknown
D-value
= 2.0 min. Calculate SAL 10-X
Population
= 1 x 106
Process
Fo = 28
A) SLR =
28 = 14
2
B) X = 14 – (log of population) - 2
= 14 – 6 – 2 = 6
C) SAL = 10-X = 10-6
