Biomedical Engineering Reference
In-Depth Information
TABLE 10.4 Assignment of Risk Factor Values by Correlation to Associated Risk
Factor Characteristics (Adapted from [24])
Risk Factors
Amount of
Bioburden
(Typically
Recovered
Quantity)
Solute
Composition
(Concentration
and Solute
Valency)
Presence of
Proteins,
Peptides or
Amino
Acids
Risk
Factor
Va l u e
Typical
Microflora
Features
Microbial
Adhesion
Risk
1
< 0.1 cfu/ml
< 1mM
monovalent or
divalent
cations
< 0.1 mg/ml
No appendages,
no
extracellular
polysaccha-
ride, low
hydrophobic-
ity
Product
2
0.1-1.0
cfu/ml
1-150 mM
monovalent
cations
1-50 mM
divalent
cations
0.1-1.0
mg/ml
Appendages or
extracellular
polysaccha-
ride,
hydrophobic
3
>
1.0 cfu/ml
>
150 mM
monovalent
cations
> 150 mM
divalent
cations
>
1 mg/ml
Spore former
Risk Factors
Amount of
Bioburden
(Typically
Recovered
Quantity)
Risk
Factor
Va l u e
Microbial
Adhesion
Risk
Surface
Smoothness
Surface
Charge
Hydrophobicity
1
< 0.1
cfu/cm 2
Electro-
polished,
< 0.30 μmRa
Net negative
Low
Equipment
/item
2
0.1-1.0
cfu/cm 2
0.30-0.70
μ
m
Neutral
Medium
Ra
3
>
1.0
cfu/cm 2
Visible
imperfections,
>
Net positive
High
0.70
μ
mRa
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