Biodegradable Plastics: Dispelling the Myths

Rebecca Daniel

We’ve all heard of bioplastics: the so called less sinister, revolutionary cousin of the now-disgraced plastic. But just how much of a truly viable alternative are these materials? Today, we delve into the world of biodegradable plastics to find out if they do exactly what they say on the packaging…

You may have heard the terms bioplastic, biodegradable, photo-degradable, oxo-degradable or compostable. Driven by the rise of the environmentally-conscious consumer, in recent years the market for eco-friendly plastic products has sky-rocketed. But with words like these increasingly being thrown around, the plethora of fancy plastic jargon leads to consumer confusion, and means making good choices can be extremely difficult. 

Many companies are switching to packaging made of ‘biodegradable plastics’. These include bioplastics, such as polylactic acid (PLA), made of plant-based material that are deemed ‘green’ and sustainable. The other type of ‘biodegradable’ plastics are oxy-degradable, which are regular plastics made from fossil fuels, which contain additives (metals) that allow the plastic to break down (i.e. fragment into smaller pieces) faster than conventional plastic in the presence of oxygen and sunlight.


“Fantastic,” we hear you say, “Plant based? Then I can put these in the bin and they will decompose naturally in landfill! And if they blow into the ocean, they won’t harm marine life - fab.”

…wrong! Welcome to the first HUGE misconception: bioplastics biodegrade like leaf litter or other plant material. ‘Biodegradable’ plastics can actually take just as long to degrade as normal plastic. If you google the small-print for your bioplastic packaging, you’ll find that these materials have certain requirements for decomposition – including a high temperature. Landfill sites usually lack oxygen and have a fairly low temperature, which isn't favourable for decomposition. A study by the University of Plymouth also found that ‘biodegradable’ bags could still hold a full load of shopping after 3 years in the sea. Watch the video here

‘Biodegradable’ plastic bags can last for years in the ocean. Photo: Enrique Talledo

‘Biodegradable’ plastic bags can last for years in the ocean. Photo: Enrique Talledo


“But what about composting?” 

Try putting a ‘biodegradable’ plastic cup in your home compost, and see how long it lasts (we’ve tried it, you’ll be waiting for a rather long while)… In order for biodegradable plastics to decompose, they need to be treated in a commercial composting facility, where there is constant aeration and temperatures are raised up to 50°C. 


“Okay, so no landfill, no home compost – but surely you can put these biodegradable products into your big green bin, or into a food waste bin as they’re made of plants?” 

WRONG AGAIN. The majority of food waste facilities in the UK use anaerobic digestion, which is not suitable for ‘biodegradable’ plastics. Additionally, until recently commercial composting facilities did not accept packaging, due to concern over incomplete decomposition, leaving residues which might contaminate the final compost product, leading to an inability to sell it as garden or farm mulch. 

Recent developments led by VegWare, a leading plant-based compostable foodservice packaging company (now that’s a mouthful!), has granted composting facilities across the UK permission to process compostable packaging materials. But what’s the catch? The packaging must have a compostability certificate and the only animal product contamination allowed is milk or cream. So, whilst this holds a small solution for our hot drinks cup problem, what about all the other ‘biodegradable’ packaging being used like cutlery, plates, containers, which might have been contaminated by other animal produce, such as meat?

Putting your ‘biodegradable’ plastics in your home compost won't do much, but you might be able to put them in your commercial compost bin. Photo: Pixabay

Putting your ‘biodegradable’ plastics in your home compost won't do much, but you might be able to put them in your commercial compost bin. Photo: Pixabay


“Ok but it’s plastic right? So you can recycle it!”

If you didn’t think it was bad enough, let us be the bearer of some more depressing news… biodegradable plastics also can’t be recycled. Polylactic acid (PLA), a common biodegradable plastic, cannot be separated from PET in recycling facilities. So, the incorrect disposal of PLA into recycling bins can cause a whole batch of PET to be discarded due to contamination. As PLA products increase in popularity, and are incorrectly disposed of, this could hugely undermine current recycling efforts. 


Still not convinced biodegradable plastics aren’t what they’re cracked up to be? Let us give you a few more reasons:

  • The additives in oxy-degradable plastics allow products to be broken down into smaller pieces, but this leads to the formation of tiny plastic fragments (microplastics). This has now been recognised, and the European Parliament passed a directive in April 2018 stating that ‘oxo-biodegradable plastic packaging shall not be considered as biodegradable”. Luckily the European Commission has started to restrict the use of oxo-plastics in the EU.

  • When ‘biodegradable’ plastics decompose without oxygen, they produce methane - a greenhouse gas 30 times more potent than carbon dioxide

  • Bio-plastics are made from plants such as corn and maize, which although is regarded as more renewable, they require water, energy, and fertilisers for production, and take up land which could be used for food production. 

So now that we’ve busted a few myths, what can you, the consumer, do to improve the plastic situation? Here are a few solutions…


As a consumer, you need to be vigilant about your plastic waste. Check the packaging, is it recyclable? Then make sure to put it in the correct bin. If there isn't one nearby, then carry it until you can recycle it at home. If you do end up buying items with biodegradable packaging - remember these can contaminate recycling, so either re-use or put them in a bin for landfill. Do some research on your local council composting, your region may be one of the few that is now accepting biodegradable plastic coffee cups and lids!


Is it actually biodegradable? If not - then don’t buy it! Watch out for ‘plant-based’ products claiming to be made of “cellulose, cassava, or maize” as this is likely PLA. 

Make sure to inform your local retailers (such as coffee shops etc.) about the issues associated with ‘biodegradable’ plastics. Email companies which have started to use these products. and Contact companies with products that you’re unsure of what the actual packaging is made from. So many companies believe they are making a better choice for our planet by making this swap. Help us to re-educate them! 

Spread the message about greenwashing ‘biodegradable’ plastics and promote a plastic-free lifestyle. Photo: Alice Forrest

Spread the message about greenwashing ‘biodegradable’ plastics and promote a plastic-free lifestyle. Photo: Alice Forrest


If something looks and feels like plastic, it’s probably going to act the same. Even if it claims to be made of plants, compostable, or biodegradable, don’t be fooled by these greenwashing companies. Making products and packaging that are ‘biodegradable’ just feeds into our consumerist, single-use mindset, and encourages us to throw items away in the belief that they will disapear. 

These plastics are not the solution. 

The most effective solution to our plastic waste problem is to use less plastic in the first place. This month we have mentioned some easy swaps, for your wardrobe, kitchen and bathroom, in our articles and review videos, that will help reduce your reliance on plastic. And look out for our Plastic Free info-posters, coming soon!

This month, The Marine Diaries will be sharing our knowledge on plastic pollution to help educate the public about the impact of our actions on marine life, in the hope of promoting change. Together we can fight plastic.

Want to become part of a community striving to reduce their plastic use? Join our Facebook group