Biodegradability and compostability testing by national and international standards

To effectively reduce the accumulation of plastic waste, biodegradable and compostable materials must decompose under the intended disposal conditions, within a reasonable timeframe, and without releasing toxic substances.

International standards for biodegradability testing provide an objective and reliable way to verify that the above criteria are met. Testing can be conducted according to various EN, ISO, ASTM, and national standards, depending on the conditions under which the material should decompose.

Industrial compostability testing

The purpose of industrial compostability testing is to ensure that biodegradable materials can be safely and effectively disposed of through the organic waste stream. In Europe, EN 13432 is the harmonized standard for determining whether packaging materials can be classified as industrially compostable.¹ To comply with the standard, packaging must meet the minimum requirements for the following four characteristics:

• Characterization of constituents: The material must contain at least 50% volatile solids and must not contain heavy metals or other toxic chemicals in concentrations that may harm the environment.

• Biodegradation: At least 90% of the material must biodegrade within 6 months in aerobic conditions. The temperature is generally set at 58 ± 2 °C, as specified in the ISO 14855 standard.

• Disintegration: After 12 weeks of aerobic composting, at least 90% of the test material (by dry weight) must pass through a 2 mm sieve.

• Ecotoxicity/compost quality: The resulting post-disintegration compost must not have a detrimental effect on plant growth.

The end user must recognize the packaging as compostable to ensure it is disposed of correctly. It should also be clearly stated whether the “compostable” label refers to the product inside the packaging or the packaging itself.

Other commonly applied industrial compostability standards that follow a similar testing procedure include EN 14995, ISO 17088, and ASTM D6400, all of which are aimed at compostable plastics. In addition, ISO 14855 on ultimate aerobic biodegradability may be used to compare alternative material formulations during product development, before confirming compostability using a more comprehensive standard.

Home compostability testing 

The conditions of a home compost differ considerably from one location to another, making it difficult to define typical temperature or humidity parameters. This is why there is currently no European or international reference standard for home compostability.² In the absence of international standards, Australian standard AS 5810 and French standard NF T51-800 are most typically used to evaluate compostability in home composts.

The parameters covered by AS 5810 are largely the same as those given in EN 13432, with the most significant difference being the conditions in which biodegradation should occur and the times allowed for decomposition. The acceptance criteria for home compostable packaging are the following:

• Characterization: The material contains at least 50% of volatile solids and heavy metal content does not exceed the specified levels, which are the same as in EN 13432.

• Biodegradability: At least 90% w/w of the material degrades in aerobic conditions within 12 months at 25 ± 5°C. Testing is performed by EN 14855.

• Disintegration: After 180 days in a controlled composting environment, at least 90% w/w of the material passes through a 2 mm sieve. Any remaining material must not be distinguishable from the compost material with the naked eye at a distance of 500 mm.

• Compost quality: The resulting compost must not negatively impact plant growth or worm survival.

Similarly to industrial compostability tests, all individual components must meet these requirements for the whole material to be labeled home compostable. 

Biodegradation in soil and marine environments

Due to the highly controlled conditions, passing the criteria for compostability does not prove that a material biodegrades in the natural environment. This is why separate biodegradation tests are needed to assess degradation in soil or water, where the material may end up accidentally or as a result of use in agriculture, horticulture, forestry, or fishing. 

ISO 23517 is the most commonly used standard for assessing biodegradability in soil. The parameters it covers include characterization of constituents, biodegradation, and ecotoxicity. Although the standard is primarily aimed at agricultural and horticultural mulch films, it may also be used to evaluate other plastic materials.

Biodegradation in marine environments is usually assessed using a combination of standards that cover aerobic biodegradation (ISO 19679, ASTM D6691) and disintegration (ISO 23832) in simulated marine conditions. Testing can also be performed in real marine conditions using an in-house method.

Our testing solutions

Measurlabs offers biodegradability and compostability testing by all the standards mentioned above. Test results can be used to support specific and verifiable biodegradability claims in accordance with the principles of the upcoming EU Green Claims Directive and existing EU policy on biobased, biodegradable, and compostable plastics. Do not hesitate to contact our experts through the form below to discuss the most suitable solution for your material.