What is the difference between biodegradable & compostable?!

‍Biodegradable simply means something that over time, is broken down into its natural components by biological organisms like bacteria and fungi. There is no limitation to how long this takes, for something to be declared biodegradable. It also doesn’t cover what it breaks down into, or under what circumstances. Some things are indeed biodegradable, but into harmful components.

Some examples of biodegradable (but not necessarily compostable) things: pretty much everything! By definition, even something as enormous and manmade as a train is biodegradable because microorganisms will break it down… it will just take quite a long time.

The Titanic is an example of an enormous metal object currently being broken down by bacteria – even though she lies almost 4km (12,500 feet) under the ocean surface.

‍Fun fact, did you know that ‘biodegradable’ plastics generate more methane than any other material as they break down in landfills? And methane is a much, much more powerful greenhouse gas than carbon dioxide.

Compostable, by contrast, means something that can be broken down, by natural processes, into non-toxic (usually nutritious) components, within a certain period of time. To truly know if something is compostable, it needs to be tested and certified. The problem is that some certified compostable substances are only certified compostable under certain circumstances. That’s why there are lots of certified compostable packets and containers out there, yet they are still sticking out of your compost heap, looking as good as the day they went in. Commercial composting is hotter (compost heaps have been known to spontaneously combust - things can get that hot), which breaks things down more readily than your smaller, less well-monitored heap will do at home.

Some examples of home compostable things: food waste, unlined cardboard, newspaper and of course, all Ethique products & packaging!

So, what is the difference then between ‘degradable’ things and biodegradable?
‍If biodegradable refers to the breakdown of something into its natural components by biological organisms like bacteria and fungi, degradable means that no living things are required to break it down- the key part of the word missing there is ‘bio’.

Most plastic is made from natural gas or oil (which is first processed into ethylene oxide). Plastic is degradable because over time the bonds in the polymers fall apart and it ‘degrades’ into microplastics. We all know by now the devastating impacts that this has on waterways and animals.

What is Oxo-degradable?
Like the above but it requires the presence of oxygen. Items such as oxo-degradable plastics are horrific for the environment and there are calls to ban them, as they trick people into assuming they are better than normal plastics. The evidence strongly states otherwise.  

Other terms you should watch out for:
‘Bio-based’, ‘made from renewable sources’ or ‘plant-based’ (when used in reference to packaging or plastics). What something is made from is actually incredibly irrelevant to how it will break down if it’s been processed.

Bio-based plastics, for example, are made from cellulose which is derived from crops such as sugar or hemp. Hemp plastic is a good example of something people tell me every day we should switch everything to, in order to solve the plastic problem. They say it’s completely compostable (it isn’t), that it produces more oxygen than carbon dioxide (nope) and that it’s renewably sourced (that’s true at least). The problem (well, actually there are a lot of problems with this idea, but the main one), is that hemp plastic acts exactly like fossil fuel-derived plastic in the long run. It doesn’t break down any faster.  

Navigating the minefield of information around us is challenging enough. The use of subjective and unregulated terms to communicate (scratch that, greenwash) people into thinking they are making an ethical and sustainable choice, is not good enough and businesses and regulatory bodies need to own up.

What to do:
If you see a brand is using these terms, reach out and ask for clarification by way of testing results and certifications. Better yet, lobby your local government or relevant agency to update their labelling terms or connect with organisations already working on petitions. The more we make clear what these terms mean, and prevent them from being used as a means to deliberately confuse consumers, the easier it is for us to navigate this minefield and make choices that are better for us and the planet.
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Sources:

• Rodale News. (2017, May 31). What does 'biodegradable' mean? Retrieved from mnn.com
• Biodegradable vs compostable vs oxo-degradable. (2020, March 30). Retrieved from greendotbioplastics.com
• Meikle, J. (2010, December 6). Steel-munching bacteria are devouring the Titanic, say scientists. Retrieved from theguardian.com
• Ibars, J. R., Moreno, D. A., & Ranninger, C. (1992, November). Microbial corrosion of stainless steel. Retrieved from ncbi.nlm.nih.gov/pubmed/1492953
• What's the Difference between Biodegradable and Compostable? (2019, February 13). Retrieved from onegreenplanet.org
• Ceres Organics. (2018, June 19). Degradable versus biodegradable versus compostable. What it all means - Ceres - Organic Food Distributors - Ceres Organics. Retrieved from ceres.co.nz
• Barrett, A. (2019, September 3). What is the Difference Between Biodegradable, Compostable and OXO Degradable? Retrieved from bioplasticsnews.com

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