What is ISO 17556 - Aerobic biodegradability of plastic materials in soil about?
ISO 17556 is an International Standard that discusses plastics. The main aim of ISO 17556 is to provide best industry test methods that demonstrate whether plastic materials are safe with regards to its impact on the environment.
ISO 17556 specifies a method for determining the ultimate aerobic biodegradability of plastic materials in soil by measuring the oxygen demand in a closed respirometer or the amount of carbon dioxide evolved. The method is designed to yield an optimum degree of biodegradation by adjusting the humidity of the test soil.
If a non-adapted soil is used as an inoculum, the test simulates the biodegradation processes which take place in a natural environment; if a pre-exposed soil is used, the method can be used to investigate the potential biodegradability of a test material.
This method applies to the following materials:
- Natural and/or synthetic polymers, copolymers or mixtures of these
- Plastic materials which contain additives such as plasticizers or colorants
- Water-soluble polymers
Note: It does not necessarily apply to materials which, under the test conditions, inhibit the activity of the microorganisms present in the soil. Inhibitory effects can be measured using an inhibition control or by another suitable method. If the test material inhibits the microorganisms in the soil, a lower test material concentration, another type of soil or a pre-exposed soil can be used.
Who is ISO 17556 - Aerobic biodegradability of plastic materials in soil for?
ISO 17556 on aerobic biodegradability of plastic materials is relevant to:
- Manufacturers of natural and synthetic polymers and copolymers, water-soluble polymers and plastics materials containing additives
- Plastic manufacturing industry
- Quality control and testing bodies
- Technical experts
- Environmental scientists and researchers
- Regulatory bodies
- Certification bodies
- Local and national authorities
Why should you use ISO 17556 - Aerobic biodegradability of plastic materials in soil?
A number of plastic materials and products have been designed for applications ending up in or on soil. They have been developed for applications where biodegradation is beneficial from a technical, environmental, social or economic standpoint. Examples can be found in agriculture (e.g. mulching film), horticulture (e.g. twines and clips, flower pots, pins), funeral items (e.g. body bags), recreation (e.g. plastic “clay” pigeons for shooting, hunting cartridges), etc. In many cases, recovery and/or recycling of these plastic items is either difficult or not economically viable. Various types of biodegradable plastics have been developed which have been designed to biodegrade and disappear in situ at the end of their useful life. Several International Standards specify test methods for determining the ultimate aerobic or anaerobic biodegradation of plastic materials in aqueous or compost conditions. However, considering the use and disposal of biodegradable plastics, it is important to establish a test method to determine the ultimate aerobic biodegradation of such plastic materials in soil.
In this regard, ISO 17556 provides best industry test methods for the same.
ISO 17556 covers guidance on Theoretical oxygen demand (ThOD) and example of a determination of the amount and the molecular mass of water-insoluble polymer remaining at the end of a biodegradation test. Example of a system for measuring the amount of carbon dioxide evolved is also provided.
Overall, if you are a manufacturer of polymers, ISO 17556 is your one-stop guide on ensuring your products play a positive role in terms of their impact on the environment.
What has changed since the last update?
BS EN ISO 17556:2019 is the third edition that replaces ISO 17556:2012, which has been technically revised. The main changes compared to the previous edition are as follows:
- The unit for BOD, COD and DIC has been corrected (see Clause 3)
- The formula for calculating the percent biodegradation has been modified (see 9.1.1)
- The test period has been revised to two years at the longest (see Clause 4)
- The number of replicates has been corrected to three (see 9.2)