You are probably already aware that the vast majority of plastics we produce and use everyday are not considered ‘biodegradable’. In recent years there has been a huge push towards using more biodegradable alternative products, to ‘save the environment’. But what does it really mean to be biodegradable though? And why does it even matter?
What is Biodegradability?
There is a lot of debate at the moment around the actual definition of ‘biodegradability’, but it essentially boils down to; “a substance or object that, under the right conditions, is capable of being decomposed (broken down) by bacteria or other living organisms”. Now this sounds like a great thing, and it is, but it can be applied to a very wide range of materials. These can include anything from natural products like wood, that would break down in the environment in weeks, to man-made ‘biodegradable’ plastics like PLA (Poly Lactic Acid), that require specialist facilities and enzymes to break them down properly. In the natural environment biodegradable plastics such as PLA can take tens or hundreds of years to break down, just like other plastics. You now see the issue; should these materials really be labelled the same when they behave so differently in the environment? Probably not!
The main problem with this really is that it may affect how someone disposes of their rubbish. If they think it is just going to break down in the environment like wood, they might just throw it in mixed waste that goes to landfill, or worse, just discard it into the environment itself. PLA itself is a great advancement in plastic recycling, as it is 100% recyclable when disposed of correctly, but you might now see how labelling it biodegradable could affect somebody’s behaviour when they are throwing it away.
In fact, consumer behaviour with regards to plastic waste is important to understand, and as a group of scientists working on developing plastic recycling methods, we felt we could contribute by gathering some data ourselves. If you can contribute, the link for our 5-minute survey can be found here (Closes End of May 2021), and all responses are completely anonymous. Going forward we feel that it is really important to give people better understanding of plastic waste and the language used when discussing it.
Why does it matter?
So, you might now see the potential issues of labelling materials such as PLA biodegradable, but I can imagine you might also be thinking; why does it actually matter?
Conventional plastics (non-biodegradable ones) are used and produced in enormous quantities. So far, since the 1950’s, over 8.3 Billion tonnes of plastic have been produced, that’s the same weight as over a billion elephants, or 25,000 empire state buildings. 79% of this plastic has ended up buried in the ground or in our oceans. This is mostly in part due to their extremely desirable properties. They are cheap to make, waterproof, resistant to chemicals, and easily moulded into various shapes and sizes. This also unfortunately makes them very hard to break down in the environment, and difficult to recycle. Just 7-9% of this plastic has been recycled.
So what effect is this having on our environment? First, plastics are contributing to the global warming by using petrochemicals (chemicals made from crude oil) in their production, and the release of greenhouse gases such as carbon dioxide, carbon monoxide, and methane, which are released when they break down or are burned. Many plastics also release harmful chemicals into the environment as they slowly break down, this is especially true of plastics that are chlorinated (contain chlorine) or have hydrogen cyanide as a breakdown product. Plastics can also cause harm to animals in terrestrial or marine environments, by physically trapping them, or by being mistaken as food and eaten. This isn’t happening on a small scale either, it is predicted that there may be as much plastic in the oceans as there is fish by 2050, as of 2014 it was at a ratio of 1:5 (plastic to fish).
Why not stop using them?
Plastics are pretty nasty in the environment, and there is a lot being put there. So why don’t we just stop using them? As you are probably well aware, this has actually been taking place in many countries around the world. You may have seen many alternatives to plastic products cropping up in recent years, especially to replace single-use plastic items. Whilst making people more aware of the plastic waste issue is great, many of these plastic alternatives actually pose a larger environmental threat than plastic. For example, a paper shopping bag is actually structurally inferior to a plastic one, meaning you might only use a paper bag once or twice before it breaks, whereas you might use a plastic bag for months or even years. The paper bag also generates between 3-4 times as much carbon dioxide to produce and transport when compared to a plastic bag made of LDPE (low-density polyethylene). This issue is the same across many products and industries, as plastics are very efficient and useful materials (why we use them in the first place).
This is why we should aim to reduce our overall usage of plastics, by replacing single-use products with re-usable alternatives (even reusable plastic ones), not replace them with single-use products that are inferior and potentially more environmentally harmful. The focus should instead be on the development of new and more efficient recycling methods. These can ‘circularise’ the plastic economy and stop plastics entering the environment by making sure that plastic waste can be completely broken down and remade into a new product for a low price, removing the need to produce plastics from petrochemicals or the need to make inefficient plastic alternatives.
This is what we are all working to achieve in the plastics group at the University of Nottingham!
Callum
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