What exactly are “bioplastics”?
The definition of the term “bioplastics” varies greatly around the world, but is most commonly used to describe bio-based, biodegradable, and/or compostable plastics. European Bioplastics, for example, defines bioplastics as plastics that are “bio-based, biodegradable, or both,” while Activesustainability.com (a top search result for “what are bioplastics?”) defines bioplastics as “biodegradable materials that come from renewable sources.” Conflicting definitions like these make “bioplastic” an unhelpful term that confuses policy-makers and consumers about the difference between bio-based, biodegradable, and compostable materials. For this reason, we avoid using the term bioplastics, and instead analyze bio-based, biodegradable, and compostable plastics separately. A brief overview of the three types of plastic and how they relate to each other is provided below, and more detailed analyses of each material can be found at the linked pages.
Bio-based plastics are plastics that are partly or entirely made from biological feedstocks such as corn or potato starch, but often still contain fossil fuels. This term refers to the source material of the plastic, regardless of its end-of-life behavior.
Biodegradable plastics are plastics that can, under certain environmental conditions, be broken down by microorganisms like bacteria and fungi into water, carbon dioxide, and naturally occurring minerals. “Biodegradable,” therefore, refers to a material’s end-of-life behavior, regardless of its component materials, which can include biological material, fossil fuels, or both.
Compostable plastics are a subset of biodegradable plastics that can fully biodegrade under the specific conditions of an industrial composting facility (this definition still refers to end-of-life behavior).
In this way, “bio-based” describes what the material is made of, while “biodegradable” or “compostable” describes the material’s end-of-life behavior under different environmental conditions.
As shown in the diagram below, plastics can be (1) bio-based but not biodegradable, (2) biodegradable but not bio-based or compostable, (3) bio-based and biodegradable but not compostable, (4) compostable and biodegradable but not bio-based, or (5) bio-based, biodegradable, and compostable.