What is the difference between Compostable and Biodegradable?

Thank you for looking for more information on this question! Here's a definition of three terms in this space, often incorrectly used interchangeably:

Compostable: This term refers to items that microbes can break down at a rate consistent with other compostable materials, with the right level of heat, water and oxygen. An important aspect of being considered compostable is that an item breaks down over a reasonable period of time (a week to several months). When composted, items should leave behind no discernible residue or toxins, and result in a nutritive soil amendment.

Biodegradable: All compostable items are considered biodegradable, but not all biodegradable items are compostable. Biodegradable packaging means it can degrade from the action of naturally occurring microorganisms such as bacteria, fungi and algae. In and of itself, the term biodegradable makes no claims as to the amount of time needed for degradation, or the attributes of the end product. Something can biodegrade, but take years to biodegrade and therefore would not be compostable. Other things can biodegrade, but leave behind high levels of toxins, contaminants and chemicals and are therefore not compostable. Other items might biodegrade but not do so in a compost environment, and are therefore not compostable.

Degradable: Degradable is a term that can be applied to anything that breaks down…or basically anything. These days, the term degradable is often referring to “oxo-biodegradable” or traditional plastic material that has been treated with an additive such that it will break down on an accelerated timeline with the right combination of sunlight (UV), heat and/or mechanical stress. The end product of oxo-biodegradable could simply be tiny fragments of the original item – as opposed to biomass (the result of composting). In some cases, these tiny fragments could then be biodegraded if they went into a second, highly controlled degradation phase.

If you're asking this question, you may be wondering if biodegradable offers the same (or at least similar) benefits as compostable materials. Here's the scoop:

  • Biodegradability in itself is a bit of a vague term that doesn’t necessarily tell you much about how to dispose of something.
    • Items that are naturally biodegradable (like paper, hemp, cotton, etc) are compostable (backyard and industrial)
    • Synthetic items that claim to be biodegradable are typically made with bioplastic. These packaging items MUST have guidance and certification as to how they should be disposed – either recycled or composted – typically in an industrial facility (and certified as compostable). Without this guidance, these items should be landfilled. Unfortunately, bioplastic is one of the biggest contaminants in both industrial composting facilities and recycling facilities today.
  • Nothing biodegrades in a landfill! Regardless of it if it is biodegradable, oxo-biodegradable or compostable, it will not degrade in any accelerated way in a landfill.
  • Degradable / oxo-biodegradable is NOT a solution to litter or ocean pollution. In fact, the Sustainable Packaging Coalition is very anti-oxo-biodegradability (preferring traditional plastic) because tiny fragments of plastic in the ocean are actually more harmful than larger bits of plastic.

In case you're looking for some more prescriptive guidance on the question of whether or not you should look for biodegradable or compostable packaging for your ecommerce business, here's our point of view in a snapshot:

  • Biodegradability as a characteristic is most important when it relates to packaging with some reasonable chance of becoming litter – candy bar wrappers, straws, plastic grocery bags. These items become litter (1) bc they are consumed on the go and/or (2) they are so light that they can easily be picked up by the wind and blown away.
  • Compostable bioplastic can also be an excellent solution in the food world. Its great for “to go” food packaging (like EcoProducts items) that need a liquid proof liner of some sort. Compostable packaging encourages food waste to be composted – which is a GREAT end of life scenario for food.
  • We are not advocates of most plastic "biodegradable" packaging options as a solution for ecommerce shipments. They are almost always 100% virgin material, they lead consumers to dispose of them badly (i.e. people landfill them thinking the packaging will "go away" quickly), they are recycled and contaminate the recycling stream, or they are composted and aren't actually certified as compostable. Even worse, often, they are oxo-biodegradable. We advise companies looking into biodegradable plastic packaging to ask lots of questions to ensure they know what they are getting so they can accurately advise their customers how to dispose of something.
  • We typically direct companies looking for biodegradable packaging to seek out naturally biodegradable options, such as paper mailers or corrugated shipping boxes. 
  • There is really no need in our industry – ecommerce packaging – for bioplastic, bc our packaging is not used for food and is highly unlikely to become litter. As such, EcoEnclose's packaging line contains:
    • Recycled and recyclable plastic (bubble mailers, poly mailers); OR
    • Paper-based and 100% recycled, which means the items are naturally biodegradable (i.e. compostable) and recyclable

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