ASTM D7473-12

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 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 will predict real world experiences based on the extent and rate of biodegradation data of the same materials obtained from the laboratory Test Method D6691. The aquarium incubated films are examined for visual degradation and dry weight loss over time. This test is not a replacement to Test Method D6691, but rather an additional ASTM method for weight attrition. The standard addresses weight loss of the plastics in a marine environment and cannot be used for demonstrating biodegradation for which Specification D7081 needs to be used.

1.2 Plastic film 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 biodegradation process.

1.3 The aquarium incubation test method allows 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 film is likely to be used and potentially disposed of in the marine environment if biodegradable criteria are met. These Aquarium studies are conducted in indoor environments, hence any sunlight-induced effects on degradation, or biodegradation, or both, are not taken into account.

1.4 Prior to conducting this aquarium test method (weight loss data) for the verification of biodegradability, Test Method D6691 shall be run on the same materials to establish quantitative levels of the plastic organic carbon oxidation and levels of carbon dioxide recovered there from. If Test Method D6691 achieves 30 % mineralization, then apply this Aquarium test and perform it. If the results from Test Method D6691 do not achieve 30 % mineralization, then aquarium incubation testing need not be done and the material shall be considered non-biodegradable in the marine environment.

1.5 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.

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 and health practices and determine the applicability of regulatory limitations prior to use.

Note 1 - There is no known ISO equivalent to this standard.