At some point, you've probably heard some of these phrases, but what do they really mean and how do they differ from each other?
Compostable:
All compostable plastics are biodegradable, but not all biodegradable plastics would be considered compostable.
Compostable plastics are those plastics which have been tested and certified by a third party to adhere to international standards for biodegradation in an industrial composting facility environment. Unless otherwise denoted, certified compostable products must be disposed of in a designated municipal composting facility, not at home. Many certified compostable materials require the higher temperatures of industrial settings to biodegrade quickly enough, or in some cases at all.
Biodegradable:
Biodegradable plastics are a relatively small subset of bioplastics which can be converted into water, carbon dioxide (CO2) and bio-mass over time with the help of micro-organisms. Nearly every material will biodegrade, given enough time. But the length of the biodegradation process is highly dependent on environmental parameters such as humidity and temperature, which is why claiming that a plastic is “biodegradable” without any further context (i.e., in what timeframe and under what environmental conditions) is misleading to consumers.
Oxo-Degradable:
While often confused with biodegradable plastics, oxo-degradables are a category unto themselves. They are neither a bioplastic nor a biodegradable plastic, but rather a conventional plastic mixed with an additive in order to imitate biodegredation. Oxo-degradable plastics quickly fragment into smaller and smaller pieces, called microplastics, but don’t break down at the molecular or polymer level like biodegradable and compostable plastics. The resulting microplastics are left in the environment indefinitely until they eventually fully break down.
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