Are Biodegradable Plastics Good For The Environment?

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Want to know if biodegradable plastics are good for the environment?  Let me talk you through the facts.

As consumers, the way products are marketed to us influence our purchasing decisions.  However, it’s often difficult to know if a product is actually green or if it’s just greenwash.  To help you navigate labels, packaging, and adverts I’m aiming to separate environmental fact from greenwash.

I’ll start with the main one that gets touted around: biodegradability.

Are Biodegradable Plastics Good for the Environment?

Plastic bags, food wrappers, nappies, and some other plastics are often labelled as biodegradable.  Manufacturers don’t explicitly say that these products are better for the environment.  However, this choice of wording implies that these are better choices for the environment.

Let’s take 5 minutes here to examine whether biodegradable plastics are good for the environment or whether it’s corporate greenwash.

greenwash 101

Conventional Plastic Vs. Biodegradable Plastics

Firstly, let’s look at the difference between conventional plastics and biodegradable plastics.

Conventional Plastic

Conventional plastics are made from petroleum-based products derived from oil.  They will either take hundreds of years to break down. Or, in the worst case, never decompose.

Biodegradable Plastics

Biodegradable plastics are made from conventional petroleum-based plastics, but also contain chemical additives.  These additives cause the plastic to break down more rapidly when exposed to air and light.  However, it could take anywhere between 2-5 years to break down, if not longer.

The other type of biodegradable plastic is known as bioplastic.  Bioplastics tend to be made from plant biomass, such as corn starch, sugar cane, or wheat.  They should either completely and rapidly break down naturally or be compostable.

However, and it’s a big, however, whether a product is biodegradable or not ultimately depends on where it ends up.

Let’s think about that last sentence for a minute, and think about where our waste goes.

Disposing Of Plastics

In order for biodegradation to occur three basic resources are required.  These being heat, light, and oxygen.  If a biodegradable plastic or bioplastic ends up in a landfill site it will never decompose.  In landfill sites waste is essentially mummified, in a complete absence of light and oxygen.  Food that has ended up in landfill will not biodegrade, so there is no hope for biodegradable plastics or even bioplastics.

You would think then that the answer is therefore to ensure that you always compost or recycle your biodegradable plastics.  Unfortunately, it’s not that simple.

Biodegradable Plastic Disposal

Most biodegradable plastics are classed as code 7. This places them in the ‘Other’ category of plastics.  Code 7 plastics are generally not accepted for recycling by local councils.  The reason being behind this is that biodegradable plastics are harder to recycle due to the addition of chemical additives in them.

What About Composting?

If you want to get around the landfill and recycling issues, and pop your biodegradable bags in your compost heap then you’ll also come a cropper.  Polyethylene, which is what biodegradable bags are commonly made from, often contains a manganese additive.  This additive stops breaking down when placed in compost bins/heaps.  Scientists think this most likely occurs due to the influence of ammonia or other gases generated by microorganisms in the compost.

Even if you were to get lucky on the composting front, and your plastics did break down then you will likely encounter another problem.  Because biodegradable plastics are made from petrochemicals they aren’t always suitable for composting.  This is because they can leave behind chemical residues in your lovely compost.  The key lesson learned here is that biodegradable is not the same as compostable.

And there’s more.  Some biodegradable plastics actually fragment rather than biodegrade.  This is due to the addition of oxidising agents (found in so-called oxo-degradable plastics).  By fragmenting, rather than degrading, they break into small pieces which can pollute soils, increase the risk of ingestion for animals and end up in our oceans and waterways.   These kinds of plastics are impossible to recover for recycling and aren’t suitable for composting.

Bioplastic Disposal

At this point, you might be thinking that surely bioplastics are a better environmental option?  The thing is, if bioplastics are sent for recycling, these types of plastic cannot be recycled with standard plastics.  This is because the additives in bioplastics can make the recycled product less durable.

Therefore the easy answer would be to ensure that you always compost bioplastics.  However, if you don’t have the ability to compost your waste (perhaps you don’t have a garden) then you are out of luck.

Don’t be so smug if you do have the ability to compost though. Some bioplastics will only compost in commercial composters, like some plastic-free tea bags.  Commercial composters reach the kind of temperatures and humidity levels you would be unable to achieve in a standard garden composter.  Therefore your bioplastics may never truly break down at home.

Other Bioplastic Points to Consider

If that isn’t enough of a headache for you, with bioplastics you also have the added headache of how the plant material that was used to create the bioplastic was grown.  Concerns include the use of GM crops and the use of valuable farmland that could be used to grow food crops.  

Other potential impacts of the growth of bioplastics crops include, but aren’t limited to deforestation, monocultures, use of freshwater supplies, soil erosion, fertiliser use (which often comes from petrochemical sources), pesticide use, food supplies, food prices, and food security.  Makes for quite heavy reading, doesn’t it?

What’s The Answer?

I’m afraid to say that there is no easy answer to the plastics conundrum. That is apart from avoiding single-use plastics where you can. And also recognising that if a product is labelled as biodegradable then it’s often not the great environmental choice that it seems.

Biodegradable plastics are rarely recyclable.  And biodegradable does not mean the same thing as compostable.  Compostable goods are often a better choice than biodegradable ones, but only if you have access to the appropriate composting facilities.

Composting biodegradable disposable nappies, for example, is almost never a good choice because of the mix you would need of green material (e.g. grass clippings, leaves, etc) to nappy.  Consider how many nappies a baby goes through in a day, and the length of time it would take for a nappy to break down at home.  You would therefore need more than a few compost heaps and a ready supply of green material to be able to compost effectively.  A better choice in this example would be washable nappies.

If you enjoyed this post then you may enjoy my post on the plastics to avoid when you’re shopping.  It covers things like the type of plastic, but also, perhaps lesser-known, the colour of plastic.  

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  1. This is a great article thank you.
    I wonder if anyone can help with my query. I am looking for a replacement to single use plastic cups at my companies canteen. They currently use slushy style ones with the dome lid. The company tries to recycle but is at a 20% output as most is tainted by food waste. All non-recyclable waste goes to into anaerobic digestion.

    Is it better to clearly mark these as recyclable? (when finished). Or to use the identical, compostable alternative?

    Appreciate there is no clear single solution and both have their positives and negatives.

    Thanks in advance.

  2. I wish i could share this to my page. Thanks so much. Its so complicated. I just want to stay away from it all. But some things need to be packaged so i think bioplastic is best as long as it can be compostable at home.

  3. Your article is now (2019) old. Addictives that biodegrade some plastic at 95 % in less than a year when 6 feet under are now available and certified. Please update it

    1. Thanks Mauro – I will need to do some research into this. Ultimately, I think reducing our consumption, reusing and recycling are still better solutions than landfill, but I will definitely look into it.

  4. I read your blog you give such a relevant information about the biodegradable products and services.Even Dwight Smith OnMedia also deals with the biodegradable products.Biodegradable products can be put in landfills where they’ll safely degrade over the course of a year.Thanks for sharing.

  5. I agree with LucaEuge. I have no question in my mind that bioplastics are worlds better than regular plastic. I view the biggest issue right now as the plastic getting out in the environment where it never degrades.
    I also fully support we MUST reduce consumption of plastics up front. But let us be realistic. How quickly will the average person or family do this?
    Just because a solution is not PERFECT it can still be an improvement. And we need changes that the mass of the US population might realistically do, not just what the small percentage who produce no waste / live on air (you rock, by the way) could do.
    We need changes and we need them FAST. I vote for focusing on further positive changes instead of discouraging interim solutions.

  6. Really interesting; but, just one little note: the fact bio-plastic doesn’t decompose in anaerobic isn’t really a bad thing, IT IS A GOOD ONE.
    Degradation is foundamental when a plastic product is into the bio-sphere (for ex. in the sea or in the upper ground) when it is insulated by the biosphere, such as in the hearth of a landfill, there isn’t any kind of problem. The important thing is that, in the case the bio-plastic for any reason migrated from the landfill to the bio-sphere can decompose in a safe and speed way.
    The reason why “mummified” bio-products in landfill ARE A GOOD THING is that they are in a so-called “CO2 Sink” it means that the CO2 contained in landfill wastes is insulated from the environment and not released in the athmosphere or in the water.
    If a petrochemical plastic is buried in a landfill the C02 balance is 0, because the item comes from fossil CO2, so, unless it where burn, it won’t release C02 anyway.
    But, in the case of organic products, they drain C02 from athmosphere and water, since the living being from which they come from had absorbed it during their life.
    Bio-products in landfills (specially forniture-wood, bones and paper) are the main reason why the C02 production of C02 great producers such as USA is a little less than scientist expected.

  7. Biotecbags in India claim to have created a truly bio-degradable plastic that uses a particular type of enzyme additive to effect the biodegradation. If you have a chance to look into the site, let know what you think of it.

  8. Thank you. This article was incredibly helpful. Though, as another comment noted, the knowledge can make life more complicated. Sigh. SaraBella, out of Portland, Oregon makes gorgeous totes out of plastic bags that were on their way to the landfill. (I have some on my new site please forgive the plug (-:

  9. I think the hurry to develop greener options cause this: new options that are not really options, just different versions of the same problem! They keep launching new types instead of finding the best and developing the required processes and infrastruture to handle it.

  10. Quiet an interesting info, I always have been known, that there is a major difference between plastics and biodegradable plastics, but you’ve made a deep research!

  11. This is really insightful! I have no garden and would turn to the biodegradable garbage bag (which I try to make sure is the only single use plastic I buy) as the ‘less damaging option’ without really considering the points you make! Ah, what to choose as an alternative though?!

    1. If it’s to use for waste going to landfill then to be honest it doesn’t matter what you use as nothing really decomposes in landfill. Biodegradable plastics are still made from oil based petrochemicals so you’re not even getting the benefit of using a product not derived from oil.

      1. Do you know of any garbage bags that are made from alternative, less damaging products? Are starches better or recycled materials? At least it will help a small bit at the production end.

          1. Thanks Wendy! Yep- I try to keep the general waste to a minimum, but I do wish supermarkets would avoid wrapping everything in single use plastic!

    2. I know it’s been a while since you posted this comment, but I think that if the type of plastic you use doesn’t directly affect the environment (as they fail to decompose in landfills anyway) then you should try to support whichever technology you think is best in the long term. The more demand there is for certain types of plastic, the more it is likely to be supported through special rubbish collections etc. and the more likely it is to be used frequently.

  12. I live in San Francisco where all buildings and businesses have a ‘green can’ for compost – including bioplastic, which are now about the only bag you can put produce in at the local healthy food markets. My question is a bit different. I’ve noticed that bioplastic bags have a terrible smell – very similar to slightly old fish. Since air and damp is what begins the composting process, I feel that the bags are composting already as I shop, and certainly in the fridge right along with my fresh organic veggies! Is this healthy??

    1. Wow, we are so far behind over here in the UK! I wouldn’t imagine the bags would cause you any problems, but if you’re at all worried then remove your fruit and vegetables from their packaging as soon as you get home. You can also buy reusable fruit and veg bags if the markets let you use them – like these ones

  13. Wow, that’s certainly eye-opening – you just re-awakened away the quieted conscience :)

    One question though regarding “Concerns include the use of GM crops”. What is the problem there? Are you concerned the introduced DNA is attacking the compost? (it will degrade just like any other plant DNA) Land and pesticide use is reduced with GE crops which is good, right?

    1. The main concern over the use of GM crops is that other crops and wild plants may become contaminated with the foreign genes added to the GM crop – e.g. from pollen, which can travel long distances on the wind/insects.

      I’ve also read that there are concerns that new ‘super-weeds’ may evolve which will be difficult or even impossible to eradicate, and may impact on local biodiversity, and there are concerns for wildlife, which may be harmed by new toxins in the environment or by changes in agricultural practices.

      1. Contamination is a little more complicated than many activists make it sound – have a look at this article which says “There is no record that any farmer in the U.S. has ever lost certification as a result of so-called “contamination” — although one would never know it based on the propaganda on the web”.

        As for the superweeds – that’s a problem with all herbicides. See this page:
        (and have a browse around the other sections, too – it’s very informative and tries to give a balanced view).
        For a more informal view, have a look at this article, especially items 6 and 7:
        Have a browse on this website, too and delve into the #Moms4GMOs articles.

        1. Aah, the GMO debate. Thanks for this – I just wanted to touch on some of the perceived problems with GMOs in this article. I think the subject is in need of a whole article and discussion for another day.

          1. I think GM is bad because a GM crop usually doesn’t create a seed or the seed created is faulty. So that basic and beautiful circle of life is taken away. If we grow too many gm crops and slowly loose our seeds it’s a big costly problem.

    2. HI
      This is completely true and that is the reason we at Timeplast have come out with a Technology in which during the time of Plastic process itself we de-polymerize 98% conventional plastics’ polymer chains (can be used with most of the plastics which has a melting point less than 500 Degree Centigrade) in to its basic low molecular weight wax structure but retains the properties of the base polymer to have its designed shelf life but 98% plastic free with reduced life time.
      Further more Timeplast treated plastics are 100% recyclable with improved properties. The good news is if it is let out in environment this will disintegrate in to wax which is digestible by soil bacteria. Treated plastic doesn’t require oxygen ,water, or microbial activity for its disintegration, for that mater this will disintegrate even in outer space. If interested please keep in touch with us for more information .