ASTM G22-23
(Practice)Standard Practice for Determining Resistance of Plastics to Bacteria
Standard Practice for Determining Resistance of Plastics to Bacteria
SIGNIFICANCE AND USE
4.1 The resin portion of plastic materials is usually resistant to bacteria, in that it does not serve as a carbon source for the growth of bacteria. It is generally the other components, such as plasticizers, lubricants, stabilizers, and colorants that are responsible for bacterial attack on plastic materials. It is important to establish the resistance of plastics to microbial attack when plastics are used under conditions of high temperature and humidity favorable for such attack.
4.2 The effects to be expected are:
4.2.1 Surface attack, discoloration, and loss of transmission (optical).
4.2.2 Removal of susceptible plasticizers, modifiers, and lubricants, resulting in increased modulus (stiffness), changes in weight, dimensions, and other physical properties, and deterioration of electrical properties such as insulation resistance, dielectric constant, power factor, and dielectric strength.
4.3 Often the changes in electrical properties are due principally to surface growth and associated moisture, and to pH changes caused by products of bacterial metabolism. Other effects include preferential growths caused by nonuniform dispersion of plasticizers, lubricants, and other processing additives. Pronounced physical changes may be observed on products in film form or as coatings where the ratio of surface to volume is high, and where nutrient materials such as plasticizers and lubricants continue to diffuse to the surface as they are utilized by the organisms.
4.4 Since attack by organisms involves a large element of change due to local accelerations and inhibitions, the order of reproducibility may be rather low. To assure that estimates of behavior are not too optimistic, the greatest observed degree of deterioration should be reported.
4.5 Conditioning of specimens such as exposure to leaching, weathering, heat treatment, etc., may have significant effects on the resistance of plastics to bacteria. Determination of these effects is not covered i...
SCOPE
1.1 This practice covers two procedures, A and B, for determining the effect of bacteria on the properties of plastics in the form of molded and fabricated articles, tubes, rods, sheets, and film materials. Procedure B provides a more extensive contact between the test bacteria and the specimens than does Procedure A. Changes in optical, mechanical, and electrical properties may be determined by the applicable ASTM methods.
1.2 The values stated in SI units are to be regarded as the standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: G22 − 23
Standard Practice for
1
Determining Resistance of Plastics to Bacteria
This standard is issued under the fixed designation G22; the number immediately following the designation indicates the year of original
adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.1 Selection of suitable specimens for determination of
pertinent properties,
1.1 This practice covers two procedures, A and B, for
3.1.2 Inoculation of specimens with suitable organisms,
determining the effect of bacteria on the properties of plastics
3.1.3 Exposure of inoculated specimens under conditions
in the form of molded and fabricated articles, tubes, rods,
favorable to growth,
sheets, and film materials. Procedure B provides a more
3.1.4 Examination and rating for visual growth, and
extensive contact between the test bacteria and the specimens
3.1.5 Removal, sterilization, and evaluation of specimens.
than does Procedure A. Changes in optical, mechanical, and
electrical properties may be determined by the applicable
NOTE 1—Since the procedure involves handling and working with
bacteria that may be capable of infecting man, it is essential that personnel
ASTM methods.
trained in microbiology perform the portion of the procedure involving
1.2 The values stated in SI units are to be regarded as the
handling of bacterial organisms and inoculated specimens.
standard.
4. Significance and Use
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4.1 The resin portion of plastic materials is usually resistant
responsibility of the user of this standard to establish appro-
to bacteria, in that it does not serve as a carbon source for the
priate safety, health, and environmental practices and deter-
growth of bacteria. It is generally the other components, such
mine the applicability of regulatory limitations prior to use.
as plasticizers, lubricants, stabilizers, and colorants that are
1.4 This international standard was developed in accor-
responsible for bacterial attack on plastic materials. It is
dance with internationally recognized principles on standard-
important to establish the resistance of plastics to microbial
ization established in the Decision on Principles for the
attack when plastics are used under conditions of high tem-
Development of International Standards, Guides and Recom-
perature and humidity favorable for such attack.
mendations issued by the World Trade Organization Technical
4.2 The effects to be expected are:
Barriers to Trade (TBT) Committee.
4.2.1 Surface attack, discoloration, and loss of transmission
(optical).
2. Referenced Documents
4.2.2 Removal of susceptible plasticizers, modifiers, and
2
2.1 ASTM Standards:
lubricants, resulting in increased modulus (stiffness), changes
D618 Practice for Conditioning Plastics for Testing
in weight, dimensions, and other physical properties, and
G21 Practice for Determining Resistance of Synthetic Poly-
deterioration of electrical properties such as insulation
meric Materials to Fungi
resistance, dielectric constant, power factor, and dielectric
strength.
3. Summary of Practice
4.3 Often the changes in electrical properties are due prin-
3.1 The procedure described herein consists of the follow-
cipally to surface growth and associated moisture, and to pH
ing steps:
changes caused by products of bacterial metabolism. Other
effects include preferential growths caused by nonuniform
dispersion of plasticizers, lubricants, and other processing
1
This practice is under the jurisdiction of ASTM Committee G03 on Weathering
additives. Pronounced physical changes may be observed on
and Durability and is the direct responsibility of Subcommittee G03.04 on
products in film form or as coatings where the ratio of surface
Biological Deterioration.
Current edition approved Feb. 1, 2023. Published February 2023. Originally
to volume is high, and where nutrient materials such as
approved in 1976. Last previous edition approved in 1996 as G22 – 76 (1996) which
plasticizers and lubricants continue to diffuse to the surface as
was withdrawn January 2002 and reinstated in February 2023. DOI: 10.1520/
they are utilized by the organisms.
G0022-23.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
4.4 Since attack by organisms involves a large element of
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
change due to local accelerations and inhibitions, the order of
Standards volume i
...
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