Significance and Use
These test methods can provide direct and unequivocal evidence of aerobic biodegradability. This requires that the radiochemical purity of the plastic is verified using Test Method D 5296.
These methods also provide the opportunity to determine the rate of biological oxidation in a complete composting environment or aqueous environment by frequent periodic sampling of carbon dioxide.
These methods provide biodegradation data at use levels of the plastic in a full cycle composting process or an aqueous system.
Scope
1.1 These test methods directly determine the rate and degree of biological oxidation of carbon in plastic materials when placed in a composting environment containing simulated municipal solid waste or an aqueous environment under laboratory conditions.
1.2 Test Method A utilizes a mixed culture derived from the target environment (waste water, sewage sludge, compost eluant, and other environmental sources). Temperature, mixing, and aeration are monitored and controlled.
1.2.1 This method has the sensitivity to determine biodegradation at concentrations commonly found in these environments.
1.3 Test Method B starts with fresh compost and proceeds through the normal composting process to an early mature stage. Temperature, aeration; and moisture are monitored and controlled.
1.3.1 This method can determine biodegradation at levels of the plastic commonly expected in municipal solid waste.
1.4 These test methods require that the target component of the plastic material be synthesized using the radioactive isotope carbon-14. Depending upon the objective, either a portion of the components of the plastic or all of the carbon can be uniformly labeled with carbon-14. The test method will determine how that labeled portion will be metabolized and biologically oxidized by the microorganisms in the system tested.
1.5 These test methods can be applied to any carbon-14 labeled compound as well as for plastic materials that have been formulated to biodegrade in a natural aerobic environment.
1.6 The synthesis and preparation of the radiolabled plastic is beyond the scope of these methods. Carbon-14 labeled polymers may be purchased from a number of commercial labs.
1.7 There are no ISO test methods that are equivalent to the test methods in this standard.
1.8 The safety problems associated with compost and radioactivity are not addressed in this standard. It is the responsibility of the user of this standard to establish appropriate safety and health practices. It is also incumbent on the user to conform to all the regulatory requirements, specifically those that relate to the use of open radioactive sources.
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 and health practices and determine the applicability of regulatory limitations prior to use.