Some plastic products are labeled as “biodegradable,” “environmentally-friendly,” or “compostable.” All of these terms imply that the product will have a minimal or no negative impact on the environment. Unfortunately, the public perception of these terms is often much more optimistic than the reality. Since September is Microplastic Awareness Month, I thought I’d try and clear up some of the confusion about these terms.

What does “biodegradable” mean?

Let me delve into the terms a little bit more. Essentially, all organic materials (things that are carbon-based) are biodegradable. Given enough time, bacteria or other organisms will decompose them. The key phrase is “given enough time.” In the case of plastics, this time could be hundreds or thousands of years. So while it is technically correct to label any plastic product as biodegradable, that does not mean that the product will “disappear” relatively rapidly.

Plastic products have not existed for long enough for us to know how long they take to biodegrade. What we do know is that the time is longer than several decades. This means that plastic items will persist in the environment for a very long time. As I heard one scientist put it, “We’re talking about a geological time scale, not a human time scale.”

The term “environmentally-friendly” is completely meaningless. There is no regulatory definition for this term.

How about “compostable”?

Of the three terms, “compostable” is the one that COULD mean that the product meets some sort of regulatory standards. If the product states that it complies with particular regulatory standards (e.g. ASTM D6400), that means that it has been tested under specific conditions, to show that it meets the requirements of these standards. The unfortunate thing, when it comes to compostable plastics, is that all of the standards define compostability in commercial or industrial composting facilities. In Florida, we do not have access to these facilities. What does that mean for us? Sadly, it means that all that we can do with compostable plastics (which are made from plants) is throw them in the trash. They will not compost in a backyard compost pile, or even in a biodigester—those do not get hot enough to compost the plastic.

For more information about plastics and bioplastics, check out the multimedia and outreach materials page at the Florida Microplastic Awareness Project’s website.

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