Selecting the most appropriate test method for demonstrating a finished product’s biodegradability can be critical for material suppliers and manufacturers.
Biodegradation product testing, when intended for product claims related to biodegradability, should incorporate several factors of the product’s actual performance. For example, products successfully tested to ‘Ready Biodegradability’ standards using the OECD 301B biodegradation test method can make claims related to that specific level of biodegradability (ex. ‘Readily Biodegradable’), but products tested to different biodegradation test standards such as the OECD 302B product test method cannot make these same claims. The same claims cannot be made due to the differences in how the methods are designed to measure biodegradation and their accommodation of different types of materials; these factors can greatly affect several parameters of the degradation process for different types of products or materials.
Because biodegradable products are often combinations of several materials or formulation components, the reliance on a ‘majority’ component biodegradability can be misleading when used as the assessment for the entire finished product. Except for the simplest products, part of the product development and marketing for biodegradable products should require product testing of the formulation components and possibly even variants of material construction.
Many factors can affect the real-life biodegradable performance of a finished product and it is not unusual to have a product fail a specific test method due to new product features associated with the finished product formulation. The most common factors affecting biodegradability are related to the water solubility or phase distributions of the material.
Biodegradation tests are used to determine the biodegradability of products in a given or intended use environment. Biodegradation testing for plastics is typically run in conditions approximating commercial composting; biodegradation tests for liquids are run in representative aquatic systems.
How Biodegradation Testing Works
- Biodegradability testing measures the complex biochemical process that occurs when microorganisms consume a given type of material.
- Although complicated, the test results measure relatively simple markers of the biodegradation process.
- A product’s ability to biodegrade depends on the amount of carbon available for microbial consumption.
- At present, regulations require biodegradability claims to be based on Aerobic Biodegradation, which typically measures oxygen consumption, CO2 production and the state of inorganic carbon intermediates.
Selecting a Method
- Challenges with biodegradation testing include the complexity of the biochemical interactions, the composition of the materials tested, and the specifc needs of each biodegradation test.
- Materials that are made up of components known to biodegrade sometimes don’t ‘pass’, and materials made of inorganic components don’t necessarily ‘fail’ the various assessments of biodegradability.
- Knowing which biodegradation test method to use for a specific material is key.
- Commonly requested biodegradation tests for solids is ISO 16929, for liquids is OECD 301, and ASTM D5864 for lubricants.
- Customers commonly request biodegradation, toxicology and bioaccumulation testing simultaneously to conduct an Environmental Fate Analysis on the product for regulatory and third party label claims.
It is highly recommended to review testing requirements with the appropriate agency prior to testing to determine which methods are required for labeling claims and regulatory acceptance.
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