ASTM D7473_D7473M-21 - Standard Test Method for Weight Attrition of Non-floating Plastic Materials by Open System Aquarium Incubations

1.1 This test method is used to determine the weight loss as a function of time of non-floating plastic materials (including formulation additives), when incubated under changing, open, marine aquarium conditions, which is representative of aquatic aerobic environments near the coasts and near the bottom of a body of water in the absence of sunlight, particularly UV and visible portions of the spectrum. The goal of this test is to obtain data that can be used to assess the potential for physical degradation of the test material. Such potential for physical degradation will be affected by real life environmental conditions.

1.2 In particular this test method does not take into consideration the possible effects of solar irradiation.

1.3 The aquarium-incubated plastic materials are examined for visual degradation and dry weight loss over time. This test does not provide information on ultimate biodegradation (that is, it is not a replacement for Test Method D6691), but it is an ASTM method for weight attrition. The standard addresses only weight loss as a function of time of the plastics materials in a marine environment and shall not be used for demonstrating ultimate biodegradation.

1.4 This test method does not provide information regarding the potential formation of microplastics due to the physical degradation of the samples.

1.5 Plastic pieces of known size and thickness are used at levels so as not to exceed the availability of micronutrients essential for and therefore limit the microbial processes.

1.6 The aquarium incubation test method allows for representative indigenous microorganisms present in seawater and marine sediment to be enriched for and carry out the biodegradation. It is recommended that the test be carried out in the geographical vicinity (latitudinal area) where the test materials are likely to be used. These Aquarium studies are conducted in indoor environments, hence any sunlight-induced effects on degradation, or biodegradation, or both, are not taken into account.

1.7 This test by itself shall not be used as the basis for claims, such as “Biodegradable in Marine Environments” since it is only a weight loss test method. This test method is solely a means for measuring a characteristic (physical degradation) under standard conditions. It does not assess the general environmental impact of plastic products.

1.8 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems has the potential to result in non-conformance with the standard.

1.9 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.

1.10 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.