ASTM G160-12(2019)

Standard Practice for Evaluating Microbial Susceptibility of Nonmetallic Materials By Laboratory Soil Burial

SIGNIFICANCE AND USE
3.1 These results may be used to compare the susceptibility of materials when exposed to this test procedure.  
3.2 Microbiological susceptibility may be reflected by a number of changes including staining, weight loss, or reduction in tensile or flexural strength.  
3.3 This practice may be considered an inoculation with a mixed culture of fungi and bacteria.
SCOPE
1.1 This practice is limited to the method of conducting an evaluation of a nonmetallic material's microbiological susceptibility when in contact with the natural environment of the soil under use conditions. This practice is intended for use on solid material test specimens that are no larger than approximately 2 cm (0.79 in.) thick and 100 cm 2  (15.5 in.2) or on film forming materials such as coatings which may be tested in the form of films at least 50 by 50 mm (2 by 2 in.) in size. This practice may be applied to articles that do not spend the majority of their service life in soil.  
1.2 A wide variety of properties may be affected by microbial attack depending on material or item characteristics. Standard methods (where available) should be used for each different property to be evaluated. This practice does not attempt to enumerate all of the possible properties of interest nor specify the most appropriate test for those properties. Test methods must, however, be appropriate to the material being tested.  
1.3 Materials intended for use in soil burial applications are often subjected to periods of exposure to solar radiation and other elements of weather for some time before they are buried. Because these exposures may alter the ability of a material to resist the effects of soil-borne microorganisms, it is recommended that this practice be combined with appropriate environmental exposures (for example, solar simulating weathering devices, the hydrolytic effects of extended aqueous contact, or extraneous nutrients) or fabrication into articles (for example, adhesive bonding of seams) which may promote microbiological susceptibility during the service life of the material.  
1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses are provided for information purposes only.  
1.5 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.  
1.6 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

• Status: Published
• Publication Date: 14-Mar-2019
• ICS: 19.040 - Environmental testing
• Technical Committee: G03 - Weathering and Durability
• Drafting Committee: G03.04 - Biological Deterioration

Relations

• Replaces: ASTM G160-12 - Standard Practice for Evaluating Microbial Susceptibility of Nonmetallic Materials By Laboratory Soil Burial
• Effective Date: 15-Mar-2019
• Refers: ASTM G154-12 - Standard Practice for Operating Fluorescent Ultraviolet (UV) Lamp Apparatus for Exposure of Nonmetallic Materials
• Effective Date: 01-Dec-2012
• Refers: ASTM G154-06 - Standard Practice for Operating Fluorescent Light Apparatus for UV Exposure of Nonmetallic Materials
• Effective Date: 05-Jun-2006
• Refers: ASTM G155-05a - Standard Practice for Operating Xenon Arc Light Apparatus for Exposure of Non-Metallic Materials
• Effective Date: 01-Oct-2005
• Refers: ASTM G155-05 - Standard Practice for Operating Xenon Arc Light Apparatus for Exposure of Non-Metallic Materials
• Effective Date: 01-Jul-2005
• Refers: ASTM G155-04a - Standard Practice for Operating Xenon Arc Light Apparatus for Exposure of Non-Metallic Materials
• Effective Date: 01-Oct-2004
• Refers: ASTM G154-04 - Standard Practice for Operating Fluorescent Light Apparatus for UV Exposure of Nonmetallic Materials
• Effective Date: 01-Oct-2004
• Refers: ASTM G155-04 - Standard Practice for Operating Xenon Arc Light Apparatus for Exposure of Non-Metallic Materials
• Effective Date: 01-Feb-2004
• Refers: ASTM G155-00 - Standard Practice for Operating Xenon Arc Light Apparatus for Exposure of Non-Metallic Materials
• Effective Date: 10-Aug-2000
• Refers: ASTM G155-00ae1 - Standard Practice for Operating Xenon Arc Light Apparatus for Exposure of Non-Metallic Materials
• Effective Date: 10-Aug-2000
• Refers: ASTM G155-00a - Standard Practice for Operating Xenon Arc Light Apparatus for Exposure of Non-Metallic Materials
• Effective Date: 10-Aug-2000
• Refers: ASTM G154-00 - Standard Practice for Operating Fluorescent Light Apparatus for UV Exposure of Nonmetallic Materials
• Effective Date: 10-Jun-2000
• Refers: ASTM G154-00a - Standard Practice for Operating Fluorescent Light Apparatus for UV Exposure of Nonmetallic Materials
• Effective Date: 10-Jun-2000
• Refers: ASTM G154-00ae1 - Standard Practice for Operating Fluorescent Light Apparatus for UV Exposure of Nonmetallic Materials
• Effective Date: 10-Jun-2000
• Referred By: ASTM D7176-22 - Standard Specification for Non-Reinforced Polyvinyl Chloride (PVC) Geomembranes Used in Buried Applications
• Effective Date: 15-Mar-2019

Overview

ASTM G160-12(2019), Standard Practice for Evaluating Microbial Susceptibility of Nonmetallic Materials by Laboratory Soil Burial, provides a recognized methodology for assessing how nonmetallic materials respond to microbiological attack when in contact with soil. Developed by ASTM International, this practice helps manufacturers and researchers determine changes in material properties-such as staining, weight loss, and reductions in tensile or flexural strength-that may indicate susceptibility to microbial degradation. By subjecting specimens to laboratory-controlled soil burial and, if required, pre-exposure to environmental factors such as solar simulation, this standard supports more reliable material selection, product development, and quality assurance in various industries.

Key Topics

• Microbial Susceptibility Evaluation
  The practice focuses on exposing nonmetallic materials-including plastics, rubber, and coatings-to soil conditions designed to foster microbial growth, featuring a mixed culture of fungi and bacteria. Resulting changes such as staining, weight loss, and physical or mechanical property loss are observed and documented.

• Test Specimen Requirements
  This standard details the acceptable sizes and types of test specimens-including solid samples no larger than 2 cm thick and 100 cm² area, or film-forming materials of at least 50 x 50 mm-ensuring consistent and meaningful results for comparative microbial resistance testing.

• Environmental Exposure Recommendations
  Materials intended for soil burial use may also be subject to environmental pre-conditioning, such as simulated solar radiation or moisture exposure, to better represent real service conditions.

• Soil and Test Conditions
  The soil used is a controlled mixture that promotes microbial activity and is maintained at specific pH and moisture levels. The exposure environment includes controlled temperature and humidity to simulate natural soil burial conditions.

• Assessment and Reporting
  The practice prescribes methods for evaluating microbial staining, visual changes, and quantitative measurements of physical properties before and after soil burial. Results are to be reported with detail on procedures, specimen condition, and any pre-exposure, supporting clear documentation and repeatability.

Applications

The ASTM G160-12(2019) standard serves a wide range of practical needs, including:

• Material Selection & Product Design
  Engineering teams apply this standard to screen candidate materials for biodegradability, fungal resistance, or general microbial durability, supporting robust product design for soil-contact or biodegradable goods.

• Quality Control & Assurance
  Manufacturers utilize these procedures during product QC to confirm that materials used will meet microbial resistance standards and maintain performance throughout their lifecycle.

• Research & Development
  Research institutions and laboratories use ASTM G160 for comparative studies and to validate new nonmetallic materials intended to resist or degrade in soil environments.

• Compliance & Specification
  Adherence to ASTM G160 provides a defensible basis for meeting client requirements, regulatory expectations, or sustainability goals regarding material performance in soil-exposed applications.

Related Standards

To ensure comprehensive evaluation and simulate broader environmental exposures, ASTM G160 can be used alongside other standards, including:

• ASTM G154 - Standard Practice for Operating Fluorescent Ultraviolet (UV) Lamp Apparatus for Exposure of Nonmetallic Materials
  Useful for simulating the effects of sunlight prior to soil burial.

• ASTM G155 - Standard Practice for Operating Xenon Arc Light Apparatus for Exposure of Non-Metallic Materials
  Applied to replicate environmental exposure scenarios before or during microbial susceptibility testing.

Using ASTM G160-12(2019) in combination with these standards enhances the accuracy and relevance of microbial resistance evaluations for nonmetallic materials, supporting industry best practices in materials science, environmental testing, and product development.

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: G160 − 12 (Reapproved 2019)
Standard Practice for
Evaluating Microbial Susceptibility of Nonmetallic Materials
By Laboratory Soil Burial
This standard is issued under the fixed designation G160; 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 responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
1.1 This practice is limited to the method of conducting an
mine the applicability of regulatory limitations prior to use.
evaluation of a nonmetallic material’s microbiological suscep-
1.6 This international standard was developed in accor-
tibilitywhenincontactwiththenaturalenvironmentofthesoil
dance with internationally recognized principles on standard-
under use conditions. This practice is intended for use on solid
ization established in the Decision on Principles for the
material test specimens that are no larger than approximately
2 2 Development of International Standards, Guides and Recom-
2 cm(0.79 in.)thickand100 cm (15.5 in. )oronfilmforming
mendations issued by the World Trade Organization Technical
materials such as coatings which may be tested in the form of
Barriers to Trade (TBT) Committee.
films at least 50 by 50 mm (2 by 2 in.) in size. This practice
may be applied to articles that do not spend the majority of
2. Referenced Documents
their service life in soil.
2.1 ASTM Standards:
1.2 A wide variety of properties may be affected by micro-
G154 Practice for Operating Fluorescent Ultraviolet (UV)
bial attack depending on material or item characteristics.
Lamp Apparatus for Exposure of Nonmetallic Materials
Standard methods (where available) should be used for each
G155 Practice for Operating XenonArc LightApparatus for
different property to be evaluated. This practice does not
Exposure of Non-Metallic Materials
attempt to enumerate all of the possible properties of interest
nor specify the most appropriate test for those properties. Test
3. Significance and Use
methods must, however, be appropriate to the material being
3.1 These results may be used to compare the susceptibility
tested.
of materials when exposed to this test procedure.
1.3 Materials intended for use in soil burial applications are
3.2 Microbiological susceptibility may be reflected by a
often subjected to periods of exposure to solar radiation and
numberofchangesincludingstaining,weightloss,orreduction
otherelementsofweatherforsometimebeforetheyareburied.
in tensile or flexural strength.
Because these exposures may alter the ability of a material to
3.3 This practice may be considered an inoculation with a
resist the effects of soil-borne microorganisms, it is recom-
mended that this practice be combined with appropriate envi- mixed culture of fungi and bacteria.
ronmentalexposures(forexample,solarsimulatingweathering
4. Soil
devices, the hydrolytic effects of extended aqueous contact, or
extraneous nutrients) or fabrication into articles (for example,
4.1 Composition—Soil shall be composed of equal parts of
adhesive bonding of seams) which may promote microbiologi-
fertile topsoil (soil with a high clay content should not be
cal susceptibility during the service life of the material.
used), well-rotted and shredded horse manure, and coarse sand
(10 to 40 mesh).
1.4 The values stated in SI units are to be regarded as
standard. The values given in parentheses are provided for
4.2 Mixing—Thesoilcompositionof4.1shouldbeprepared
information purposes only.
by simple mixing and sifting through ⁄4 in. mesh screen.
1.5 This standard does not purport to address all of the
4.3 Aging—The mixture is aged for three months and
safety concerns, if any, associated with its use. It is the
resifted twice at four-week intervals during the three months.
Afterthreemonths,aviabilitycontrolofuntreatedcottoncloth,
This practice is under the jurisdiction ofASTM Committee G03 on Weathering
and Durability and is the direct responsibility of Subcommittee G03.04 on
Biological Deterioration. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved March 15, 2019. Published March 2019. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1998. Last previous edition approved in 2012 as G160 – 12. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/G0160-12R19. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G160 − 12 (2019)
2 2
400 to 475 g⁄m (12 to 14 oz⁄yd ), buried in the soil shall have various stages of fungal attack will be variable. The ASTM
a tensile strength loss of at least 50 % after five days. Manual 7 may be used as a guide.
NOTE 1—The soil mixture may be used for sequential tests as long as
the cotton cloth control degrades within the specified time period.
7. Solar-Simulating Weathering Devices
7.1 For those soil burial applications in which the materials
4.4 pH—The soil shall have a pH between 6.5 to 7.5,
checked periodically, and maintained by the addition of ground are expected to be exposed to environmental conditions,
including solar radiation, it is recommended that they be
limestone to raise the pH or flowers of sulfur to lower the pH.
The soil pH may be taken by dispersing 1 weight part soil in exposed in a laboratory accelerated weathering device prior to
soil burial. The type and duration of exposure shall be agreed
20 parts of water, shaking or stirring, then allowing the mix to
upon by interested parties. The duration shall be of sufficient
settle for 1 h. The pH is measured with indicator paper,
electrodes, or by titration. length, known by previous experience to have reduced the
resistance of some materials to the effects of soil-borne
4.5 Moisture—The soil shall be maintained at between 20
microorganisms. If used, the type and duration of exposure
and 30 % moisture, based on the dry weight of the soil. (The
shall be completely described in the Test Report.
percent moisture is calculated by weighing approximately
7.2 The two types of weathering devices described in the
50 mL of a representative portion and taking the portion to
Practices listed below have been used historically prior to
constant weight by placing the soil in an oven at a temperature
evaluation of the microbial susceptibility of nonmetallic mate-
of 101 to 106 °C.) Water lost during use as a result of
rials by laboratory soil burial. Because of differences in the
evaporationshallbereplacedwithoutdeformingthesoilbed.If
spectral power distributions of the exposure sources as well as
the surrounding atmosphere is maintained at 85 to 95 %
the other conditions in the two types of laboratory weatherin
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