Recently I’ve been trying to focus on de-cluttering my home and whilst we must all aim to reuse and repurpose there were items that just weren’t fit for a new life. Having bought some biodegradable rubbish bags from a local store, when I took the first one out I wondered whether biodegradable garbage bags really are…. well, biodegradable. So I did some research.
Biodegradable garbage bags are biodegradable however they need specific environmental conditions to degrade quickly. These conditions are rarely seen in the natural environment and so most biodegradable plastic bags that are discarded will not degrade for years to come.
So let’s get into the detail of what I discovered but before we do if you are interested in compostable garden waste bags then you may want to read my article “Compostable Bags for the Green Bin – Should You Use Them?” next.
What is the Difference Between Degradable, Biodegradable and Compostable Bags
The first thing I found was that there are a few different types of garbage bags that could be suitable, compostable, biodegradable, and then there’s degradable. But which one should you choose?
Although the word degradable seems like it should be good for the environment we should try to avoid degradable plastic bags wherever possible.
These types of plastic bags do degrade and so when we think about bags staying around for hundreds of years, with the right treatment and conditions degradable bags will actually break down.
However, the issue here is that they break down into hundreds if not thousands of small pieces of plastic which we now refer to as microplastics.
There’s a huge amount of information on the internet about microplastics so I won’t go into detail here but needless to say that once consumed, they are incredibly dangerous to all types of animals. Now seen across the world, microplastics are passed from animal to animal through the natural food chain where microplastics have even been found in humans.
Best to avoid these types of bags but if you can’t don’t just discard them thinking they will degrade, make sure they are properly disposed of.
From their name, Biodegradable plastic bags sound great however there are a few things we should know before we start to use them.
Biodegradable plastic bags are generally made from plant-based material such as corn or wheat starch and they have specific additives added to promote the discarded bag to break down.
So although these bags will break down much quicker than degradable plastic bags one of the key issues is that to do so they need to be exposed to specific environmental conditions. High temperature, UV and oxygen are the main ones all of which may not necessarily exist where the bag is discarded.
Made from 100% organic material such as plant starch these types of plastic bags do not leave behind any hazardous byproducts. All the material in the bag will simply return to the earth however there are still issues with compostable plastic bags.
The main problem with some compostable plastic bags is that as with biodegradable plastic bags they need certain environmental conditions for the composting process to occur.
For some bags, this means that you cannot simply toss the plastic bag onto your compost heap at home unless they are specifically made for home composting.
If the compostable plastic bags you buy are not suitable for home composting then they would need to go to a special council compositing site of which there aren’t that many.
Degradable vs Biodegradable vs Compostable Bags – Which is best?
Out of the three options, compostable bags are the best. They are constructed of nutrient-rich components that, when broken down, leave nothing but natural material behind.
They also biodegrade at a faster pace, leaving no evidence behind however you do need to check that you can responsibly dispose of them either at home or at your local recycling facility.
Overall, they are far more environmentally friendly than standard polyethene.
How Long Does it Take for a Biodegradable Plastic Bag to Decompose?
We do need to be careful using the term “biodegradable” as it can be misleading. You’d imagine that once such bags are discarded, they magically degrade spontaneously with nothing left behind, right?
Sadly this is not the case.
The truth is that biodegradable plastics require extremely high temperatures and humid conditions to decompose. With this in mind, it is extremely rare, if not impossible to occur in the natural environment where most bags are discarded.
Under the correct conditions, biodegradable bags can degrade completely in 3-6 months however the conditions required can only really be achieved in a manufactured way.
For the breakdown process to begin, the temperature must be above 50°C, which in the natural world is rare to occur even in the hottest of countries and is definitely not possible in our oceans.
The process also requires UV exposure, again difficult in the Nordics where sunlight in winter months only appears for a couple of hours a day.
One key point is that biodegradable plastic bags are not recyclable so they end up buried in landfills which ultimately means that they are very unlikely to see any sunlight again.
So, how long does a biodegradable bag take to degrade?
Well, it depends on so many factors but my guess is that it’s still a very long time indeed.
Are Biodegradable Garbage Bags Environmentally Friendly?
Given the research and information I’ve gathered over the last week or so, I would say they are not eco-friendly even though retailers are hailing them as a success.
Researchers at the University of Plymouth (the most famous research, cited by many sources I have read) in the United Kingdom recently examined five different types of plastic carrier bags, including two types of oxo-biodegradable bags, one biodegradable bag, one compostable bag, and a typical high-density polyethylene plastic bag.
Here is a video clip from the University of Plymouth.
They discovered no clear evidence that bioplastic bags, including biodegradable and compostable bags, provide an environmental advantage over conventional plastics because they have been shown to linger in the environment for an extended period of time.
Furthermore, experts expressed worry that biodegradable plastic bags, in particular, could be fragmented into microplastics, having the same environmental impact as typical single-use plastic bags – partially decomposed compostable or biodegradable bags could be consumed by animals and enter the food chain, offering certain health hazards.
Greenpeace and the Environmental Investigation Agency (EIA) have recently issued a stern warning against the use of biodegradable and compostable plastics, calling them a false solution.
They point out that the vast bulk of bioplastic comes from agricultural feedstock, which competes with food crops. As a result, bioplastic endangers food security, contributes to biodiversity loss, and increases agricultural emissions.
Here is the Greenpeace report – “Biodegradable Plastics: Breaking Down the Facts“
Rather than opting for a dubious solution, Greenpeace and the EIA strongly advise focusing on reduction and reuse.
To be fair, even though all three of these are better than the plastic bags of old I couldn’t agree more.