ASTM D6691-24

Standard Test Method for Determining Aerobic Biodegradation of Plastic Materials in the Marine Environment by a Defined Microbial Consortium or Natural Sea Water Inoculum

SIGNIFICANCE AND USE
5.1 The use of plastics aboard ships is on the rise and the use of the sea as a trash dumping site is no longer a possibility; consequently, the disposal of plastic materials while at sea remains a major issue. It is possible that biodegradable plastics will help to allay public concern by allowing for the safe disposal of plastic materials at sea. This test method has been developed to assess the rate and degree of aerobic biodegradation of plastics exposed to marine microorganisms. Aerobic biodegradation is determined by measuring the amount of biogas (carbon dioxide) produced during such an exposure.  
5.2 It is acceptable to use the degree and rate of aerobic biodegradability of a plastic under the conditions of this test method to estimate the persistence of that plastic in biologically active marine environments, for example, seashore and open-ocean. However, it shall be recognized that predicting long-term environmental fate and effects from the results of short-term exposure to a simulated marine environment is difficult. Thus, caution shall be exercised when extrapolating the results obtained from this or any other controlled-environment test to disposal in the natural environment.
SCOPE
1.1 This test method is used to determine the degree and rate of aerobic biodegradation of plastic materials (including formulation additives) exposed to pre-grown population of at least ten aerobic marine microorganisms of known genera or the indigenous population existing in natural seawater. The test method is conducted under controlled laboratory conditions.  
1.2 This test method is designed to index polymer materials that are possibly biodegradable, relative to a positive reference material, in an aerobic environment.  
1.3 This test method is applicable to all polymer materials containing at least 20 % carbon that are not inhibitory to the microorganisms present in a marine environment.  
1.4 The values stated in SI units are to be regarded as the standard.  
1.5 There is no known ISO equivalent to this standard.  
1.6 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.  
1.7 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-Feb-2024
• ICS: 13.030.99 - Other standards related to wastes
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.96 - Environmentally Degradable Plastics and Biobased Products

Relations

• Replaces: ASTM D6691-17 - Standard Test Method for Determining Aerobic Biodegradation of Plastic Materials in the Marine Environment by a Defined Microbial Consortium or Natural Sea Water Inoculum
• Effective Date: 15-Feb-2024
• Referred By: ASTM D7473/D7473M-21 - Standard Test Method for Weight Attrition of Non-floating Plastic Materials by Open System Aquarium Incubations
• Effective Date: 15-Feb-2024

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: D6691 − 24
Standard Test Method for
Determining Aerobic Biodegradation of Plastic Materials in
the Marine Environment by a Defined Microbial Consortium
1
or Natural Sea Water Inoculum
This standard is issued under the fixed designation D6691; 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* D883 Terminology Relating to Plastics
D1193 Specification for Reagent Water
1.1 This test method is used to determine the degree and rate
D2593 Test Method for Butadiene Purity and Hydrocarbon
of aerobic biodegradation of plastic materials (including for-
Impurities by Gas Chromatography
mulation additives) exposed to pre-grown population of at least
D4129 Test Method for Total and Organic Carbon in Water
ten aerobic marine microorganisms of known genera or the
by High Temperature Oxidation and by Coulometric
indigenous population existing in natural seawater. The test
Detection
method is conducted under controlled laboratory conditions.
1.2 This test method is designed to index polymer materials
3. Terminology
that are possibly biodegradable, relative to a positive reference
3.1 Definitions of Terms Specific to This Standard—
material, in an aerobic environment.
Definitions of terms applying to this test method appear in
1.3 This test method is applicable to all polymer materials
Terminology D883.
containing at least 20 % carbon that are not inhibitory to the
microorganisms present in a marine environment.
4. Summary of Test Method
1.4 The values stated in SI units are to be regarded as the
4.1 This test method consists of the following:
standard.
4.1.1 Selecting and characterizing (carbon content, molecu-
1.5 There is no known ISO equivalent to this standard.
lar weight) plastic materials for testing,
1.6 This standard does not purport to address all of the
4.1.2 Preparing a uniform inoculum of various isolated
safety concerns, if any, associated with its use. It is the marine microorganisms, or obtaining a natural sea water
responsibility of the user of this standard to establish appro-
sample (with added inorganic nutrients) for the test relying on
priate safety, health, and environmental practices and deter-
the microbes present as the inoculum.
mine the applicability of regulatory limitations prior to use.
4.1.3 Exposing the test materials to the inoculum,
1.7 This international standard was developed in accor-
4.1.4 Using a respirometer to measure the total biogas
dance with internationally recognized principles on standard-
(CO ) produced as a function of time, and
2
ization established in the Decision on Principles for the
4.1.5 Assessing the degree of biodegradability.
Development of International Standards, Guides and Recom-
4.2 Biodegradability is assessed by determining the propor-
mendations issued by the World Trade Organization Technical
tion of polymer-C converted to biogas-C. The percent of
Barriers to Trade (TBT) Committee.
theoretical gas production, expressed as a fraction of the
measured or theoretical carbon content of the test material, is
2. Referenced Documents
2 reported as a function of time.
2.1 ASTM Standards:
D618 Practice for Conditioning Plastics for Testing
5. Significance and Use
1
This test method is under the jurisdiction of ASTM Committee D20 on Plastics
5.1 The use of plastics aboard ships is on the rise and the use
and is the direct responsibility of Subcommittee D20.96 on Environmentally
of the sea as a trash dumping site is no longer a possibility;
Degradable Plastics and Biobased Products.
consequently, the disposal of plastic materials while at sea
Current edition approved Feb. 15, 2024. Published April 2024. Originally
remains a major issue. It is possible that biodegradable plastics
approved in 2001. Last previous edition approved in 2017 as D6691 - 17. DOI:
10.1520/D6691-24.
will help to allay public concern by allowing for the safe
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
disposal of plastic materials at sea. This test method has been
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
developed to assess the rate and degree of aerobic biodegra-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. dation of plastics exposed to marine microorganisms. Aerobic
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Con
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D6691 − 17 D6691 − 24
Standard Test Method for
Determining Aerobic Biodegradation of Plastic Materials in
the Marine Environment by a Defined Microbial Consortium
1
or Natural Sea Water Inoculum
This standard is issued under the fixed designation D6691; 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*
1.1 This test method is used to determine the degree and rate of aerobic biodegradation of plastic materials (including formulation
additives) exposed to pre-grown population of at least ten aerobic marine microorganisms of known genera or the indigenous
population existing in natural seawater. The test method is conducted under controlled laboratory conditions.
1.2 This test method is designed to index polymer materials that are possibly biodegradable, relative to a positive reference
material, in an aerobic environment.
1.3 This test method is applicable to all polymer materials containing at least 20 % carbon that are not inhibitory to the
microorganisms present in a marine environment.
1.4 The values stated in SI units are to be regarded as the standard.
1.5 There is no known ISO equivalent to this standard.
1.6 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.
1.7 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.
2. Referenced Documents
2
2.1 ASTM Standards:
D618 Practice for Conditioning Plastics for Testing
D883 Terminology Relating to Plastics
D1193 Specification for Reagent Water
D2593 Test Method for Butadiene Purity and Hydrocarbon Impurities by Gas Chromatography
1
This test method is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.96 on Environmentally Degradable
Plastics and Biobased Products.
Current edition approved Dec. 1, 2017Feb. 15, 2024. Published January 2018April 2024. Originally approved in 2001. Last previous edition approved in 20092017 as
D6691 - 09.D6691 - 17. DOI: 10.1520/D6691-17.10.1520/D6691-24.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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D6691 − 24
D4129 Test Method for Total and Organic Carbon in Water by High Temperature Oxidation and by Coulometric Detection
3. Terminology
3.1 Definitions of Terms Specific to This Standard—Definitions of terms applying to this test method appear in Terminology D883.
4. Summary of Test Method
4.1 This test method consists of the following:
4.1.1 Selecting and characterizing (carbon content, molecular weight) plastic materials for testing,
4.1.2 Preparing a uniform inoculum of various isolated marine microorganisms, or obtaining a natural sea water sample (with
added inorganic nutrients) for the test relying on the microbes present as the inoculum.
4.1.3 Exposing the test materials to the inoculum,
4.1.4 Using a respirometer to measure the total biogas (CO ) produced as a function of time, and
2
4.1.5 Assessing the degree of biodegradability.
4.2 Biodegradability is assessed by determining the proportion of polymer-C converted to biogas-C. The percent of theoretical gas
production, expressed as a fraction of the measured or theoretical carbon content of the test material, is reported as a function of
time.
5. Significance and Use
5.1 The use of plastics aboard ships is on the rise and the use of the sea as a trash dumping site is no longer a possibility;
consequently, the disposal of plastic materials while at sea remains a major issue. It is
...