ASTM D6692-01
(Test Method)Standard Test Method for Determining the Biodegradability of Radiolabeled Polymeric Plastic Materials in Seawater (Withdrawn 2010)
Standard Test Method for Determining the Biodegradability of Radiolabeled Polymeric Plastic Materials in Seawater (Withdrawn 2010)
SIGNIFICANCE AND USE
This method allows for a definitive determination concerning aerobic microbial biodegradation occurring for plastic compounds of known uniform composition or of component materials used in the production of non-uniform (that is, blend) plastics.
The use of radioactive 14C materials eliminates the possibility of carbon dioxide measurement from anything other than the parent compound in question.
The use of this assay relies on the enrichment and growth of naturally occurring microbes in marine samples to biodegrade the radiolabeled plastic compounds generating cell material and carbon dioxide as the radiolabeled end products.
Time course (several days to several weeks) measurements allows for a biodegradation rate determination to be made, but caution should be exercised in extrapolating this laboratory determined rate to what may actually occur in an open system marine environment which may experience fluctuations in nutrient availability, oxygen and temperature.
It may be necessary to repeat this test more than once (depending on the season of water sampling) since microbial populations vary significantly over time and location.
The seawater inoculum may be run with a sample (k 10 gram quantities) of marine sediment added to the seawater inoculum to increase the microbial diversity in establishing an enrichment capable of biodegrading the polymer being tested.
SCOPE
1.1 This test is used to determine the degree of aerobic biodegradation of polymeric compounds utilized in plastic materials by determining the level of respiration of such radiolabeled carbon compounds to radiolabeled carbon dioxide.
1.2 The test is designed to utilize the naturally occurring microbes in seawater as the inoculum for the enrichment and subsequent mineralization (biodegradation) of the test polymer using it as a carbon and energy source resulting in a carbon dioxide as an end product.
1.3 The test method requires that the polymers to be assayed are synthesized using the radioisotope, carbon-14, and that the compound or plastic material be uniformly labeled with carbon-14.
1.4 As controls, known biodegradable compounds, such as glucose or starch, also uniformly labeled with carbon-14, are run in order to determine the biological activity of the natural population.
1.5 The concentration of added polymers shall be kept low so as not to cause limitation by oxygen, and the seawater inoculum is amended with nitrogen and phosphorus compounds to ensure that growth in not limited by these nutrients.
1.6 The safety problems and regulations associated with working with radioactive materials are not addressed in the method. It is the responsibility of the individual users to establish and ensure adherence the proper safety, health, monitoring and all regulatory practices associated with the use of radioactive compounds.
1.7 There is no similar or equivalent ISO standard.
WITHDRAWN RATIONALE
This test method was used to determine the degree of aerobic biodegradation of polymeric compounds utilized in plastic materials by determining the level of respiration of such radiolabeled carbon compounds to radiolabeled carbon dioxide.
Formerly under the jurisdiction of Committee D20 on Plastics, this test method was withdrawn in February 2010 in accordance with subsection 10.5.3.1 of the Regulations Governing ASTM Technical Committees, which requires that standards shall be updated by the end of the eighth year since the last approval date.
General Information
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information.
Designation:D6692–01
Standard Test Method for
Determining the Biodegradability of Radiolabeled Polymeric
Plastic Materials in Seawater
This standard is issued under the fixed designation D6692; 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 D5296 Test Method for Molecular Weight Averages and
Molecular Weight Distribution of Polystyrene by High
1.1 This test is used to determine the degree of aerobic
Performance Size-Exclusion Chromatography
biodegradation of polymeric compounds utilized in plastic
D6340 Test Methods for Determining Aerobic Biodegrada-
materials by determining the level of respiration of such
tion of Radiolabeled Plastic Materials in an Aqueous or
radiolabeled carbon compounds to radiolabeled carbon diox-
Compost Environment
ide.
1.2 The test is designed to utilize the naturally occurring
3. Terminology
microbes in seawater as the inoculum for the enrichment and
3.1 Definitions of Terms Specific to This Standard:
subsequent mineralization (biodegradation) of the test polymer
3.1.1 disintegrations per minute (DPM), n—the degree of
using it as a carbon and energy source resulting in a carbon
radioactivity of an element given as the number of decays
dioxide as an end product.
occurring per unit time.
1.3 Thetestmethodrequiresthatthepolymerstobeassayed
3.1.2 microcurie (µCi), n—a unit of radioactivity equal to
are synthesized using the radioisotope, carbon-14, and that the
/1,000,000 of a curie or 2.2 3 10 DPM.
compound or plastic material be uniformly labeled with
3.1.3 millicurie (mCi), n—a unit of radioactivity equal to
carbon-14.
1/1000 of a curie.
1.4 As controls, known biodegradable compounds, such as
3.1.4 natural seawater (NSW), n—seawater unamended
glucose or starch, also uniformly labeled with carbon-14, are
with any additives.
run in order to determine the biological activity of the natural
3.1.5 specific activity (SA), n—the level of radioactivity
population.
(µCi) per unit mass (for example, mg).
1.5 The concentration of added polymers shall be kept low
so as not to cause limitation by oxygen, and the seawater
4. Summary of Test Method
inoculum is amended with nitrogen and phosphorus com-
4.1 This test method consists of the following:
pounds to ensure that growth in not limited by these nutrients.
4.1.1 Obtaining samples of the test polymer in which the
1.6 The safety problems and regulations associated with
carbon is uniformly labeled with carbon-14 and of known
working with radioactive materials are not addressed in the
specific activity.
method. It is the responsibility of the individual users to
4.1.2 Collecting a sample of natural seawater (NSW) from a
establish and ensure adherence the proper safety, health,
marine source in which the material (non-radioactive) may be
monitoring and all regulatory practices associated with the use
ultimately disposed.
of radioactive compounds.
4.1.3 Incubating, over a time course, weighed samples of
1.7 There is no similar or equivalent ISO standard.
the polymer in sealed vessels of NSW amended with nutrients
2. Referenced Documents under aerobic conditions at constant temperature.
2 4.1.4 At varied time points, harvesting the microbially
2.1 ASTM Standards:
respired radiolabeled carbon dioxide in absorbent traps.
D883 Terminology Relating to Plastics
4.1.5 Determining the DPM of radiolabeled carbon dioxide
in a liquid scintillation counter.
This test method is under the jurisdiction ofASTM Committee D20 on Plastics
4.1.6 BasedontherecoveredDPM,thespecificactivityand
and is the direct responsibility of Subcommittee D20.96 on Environmentally
the known amount of radiolabeled polymer added to the test
Degradable Plastics.
incubation vessel calculate the amount and percentage of the
Current edition approved June 10, 2001. PublishedAugust 2001. DOI: 10.1520/
D6692-01.
polymer which was respired (biodegraded) to carbon dioxide.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
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D6692–01
5. Significance and Use 7.2.3 Methyl Benzethonium Hydroxide, a 1.0 molar solution
in methanol.
5.1 This method allows for a definitive determination con-
7.2.4 Hydrochloric Acid (HCl), a 4.0 N solution.
cerning aerobic microbial biodegradation occurring for plastic
7.3 Serum Bottles (120 ml), autoclaved and used for incu-
compounds of known uniform composition or of component
bation vessels.
materials used in the production of non-uniform (that is, blend)
7.4 Buna-n Rubber Serum Bottle Seals (20 mm), with a
plastics.
tetrafluoroethylene inner surface (flange type)—see footnote .
5.2 The use of radioactive C materials eliminates the
7.5 Aluminum Seals and Crimper, for flange type serum
possibilityofcarbondioxidemeasurementfromanythingother
bottle seals.
than the parent compound in question.
7.6 Sleeve Type Red Rubber Serum Stoppers.
5.3 The use of this assay relies on the enrichment and
7.7 Natural Seawater (NSW), collected on or before (1 to 2
growth of naturally occurring microbes in marine samples to
days) the day the assay is to be initiated. There are no
biodegrade the radiolabeled plastic compounds generating cell
limitations on the collection of this seawater. Avoid collection
material and carbon dioxide as the radiolabeled end products.
sites that are directly influenced by storm water runoff or that
5.4 Time course (several days to several weeks) measure-
have major oil slicks on the surface.
ments allows for a biodegradation rate determination to be
7.8 Plastic Center Wells, see footnote.
made, but caution should be exercised in extrapolating this
7.9 Filter Paper Pieces, (0.5 by 5 mm—cut and fluted).
laboratory determined rate to what may actually occur in an
7.10 Scintillation Vials.
open system marine environment which may experience fluc-
7.11 Scintillation Cocktail.
tuations in nutrient availability, oxygen and temperature.
7.12 Syringes and Needles.
5.5 It may be necessary to repeat this test more than once
(depending on the season of water sampling) since microbial
8. Hazards
populations vary significantly over time and location.
8.1 This test method requires the use of hazardous materials
5.6 The seawater inoculum may be run with a sample (ë 10
including hazardous chemicals such as acid and base, hypo-
gram quantities) of marine sediment added to the seawater
dermic needles, and radioisiotopes.
inoculum to increase the microbial diversity in establishing an
8.2 When using chemicals such as the carbon dioxide
enrichment capable of biodegrading the polymer being tested.
absorbent (caustic) instructions in the Material Data Safety
6. Apparatus
Sheets must be followed.
8.3 The technique involves the use of radioactive C com-
6.1 Hood, allowing for radiochemical work should be avail-
pounds and the protocols of Federal and State safe handling
able with a face velocity of approximately 100 cubic feet/min.
and disposal of radioisotopes must be followed.
6.2 Micro Balance, (accurate to 6 0.1 mg) should be
available for weighing out radiolabeled materials.
9. Radiolabeled Test Materials
6.3 Liquid Scintillation Counter, is needed for determina-
9.1 The purity of the radioactive compound to be tested
tion of the DPM of the recovered radiolabeled carbon dioxide.
shall be established to verify that it is the only radiolabeled
A multiple or single sample counter can be used.
compound and that C carbon is not present in any other
6.4 Oxidizer,capableofcombustingweighedsamplesofthe
material. This verification shall come from the manufacturer
test material to CO may be necessary if the specific activity
who synthesized the compound and also who determines its
reported by the manufacturer needs to be verified.
specific activity (SA).
6.5 Autoclave, capable of steam sterilizing seawater is
9.2 If necessary, the specific activity of the radiolabeled
necessary for preparing sterile (negative) controls which are
compound may be verified by combustion of weighed samples
used for volatilization calculations. The autoclave is run at
using an oxidizer instrument. A liquid scintillation counter is
121°C for 20 min.
used for counting the recovered DPM of the combusted sample
7. Reagents and Materials
and the specific activity calculated in accordance wi
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