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. The test method is conducted under controlled laboratory conditions. This test method is designed to index polymer materials that are possibly biodegradable, relative to a positive reference material, in an aerobic environment. 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. The values stated in SI units are to be regarded as the standard. There is no similar or equivalent ISO standard. 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.