The Truth About Biodegradable and Compostable Bags is Out - But No One is Asking the Right Questions

If you’ve been proudly accepting biodegradable bags while out shopping and chucking them in your compost bin - STOP RIGHT NOW. And keep reading.

Three years ago, Richard Thompson, a British marine biologist who studies plastic waste, decided to find out for himself if the claims about biodegradable and compostable bags were true. In 2015, he and his graduate students at Plymouth University took several test subjects and placed them in three different environments: immersed in water, buried in soil, or exposed to outdoor air (like litter).

The results are in and they aren’t pretty: after long-term exposure to the sea, air and earth, none of the five types of bags studied fully decomposed in all the tested environments. Not only did they stay in tact, some of them could still hold 5 pounds of groceries as Marine Scientist Imogen Napper - one of the graduate students leading the study - demonstrated in a tweet.

The results of the first-of-its-kind research were published on April 28th in the journal Environmental Science & Technology and conclude that none of the bags decomposed substantially enough in all the environments they were tested in to give them any environmental advantages over regular plastic bags. Three years is more than enough time for a sea turtle to confuse a biodegradable bag for a jellyfish and choke on it.

Untitled design-54.jpg

“It is therefore not clear that the oxo-biodegradable or biodegradable formulations provide sufficiently advanced rates of deterioration to be advantageous in the context of reducing marine litter, compared to conventional bags.” - Environmental Deterioration of Biodegradable, Oxo-biodegradable, Compostable, and Conventional Plastic Carrier Bags in the Sea, Soil, and Open-Air Over a 3-Year Period

Not all bags are created equal

Thompson and his team tested five types of single-use bags: one compostable bag, one conventional plastic bag, and three kinds of biodegradable bags (two of which were oxo-biodegradable and the other manufactured in a way that promotes its breakdown differently).

While none of the bags could be relied on to substantially deteriorate over a three-year period in all environments, the different materials performed differently in each environment. For example, while the biodegradable bag placed in the soil could hold 5 pounds of groceries at the study's completion, the compostable bag in the same environment was substantially weaker and could not hold the groceries.

In the underwater environment, the compostable bag disappeared completely within three months while the rest of the test subjects remained in tact for the duration of the study. But don’t get too excited: while it may have disappeared, the researchers emphasized the necessity to further explore the breakdown byproducts and what the environmental consequences might be.

After 9 months in the open air environment, all the bags either became too brittle to continue testing or had shattered into microplastic pieces (one of the primary complaints about oxo-biodegradables is that they include additives to speed up break down and this results in micro-plastic pollution. The EU even recommended banning them last year).

Consumer confusion

Compostable and biodegradable materials also have the potential to contaminate regular waste streams as many consumers don’t know how to properly dispose of them. If a biodegradable bag ends up in a recycling bin, for example, it has the potential to contaminate a whole batch of recyclables making them unviable.

Compostable bags can’t just be thrown in the soil - they don’t decompose in a garden or in the regular waste stream. For instance, if you plug the terms ‘compostable plastic’ or ‘biodegradable plastic’ into the TOwaste app, it will tell you to put them in the garbage. Toronto doesn’t have a facility to manage the composting process of these materials.

“Discarding a product in the environment is still littering, compostable or otherwise. Burying isn’t composting. Compostable materials can compost with five key conditions – microbes, oxygen, moisture, warmth and time.” - Vegware, quoted in The Guardian

The researchers voiced concerns over the way biodegradable products get marketed. Their marketing seems to suggest they can be thrown right into the natural environment, but  the results of this most recent study  suggest otherwise.

The researchers voiced concerns over the way biodegradable products get marketed. Their marketing seems to suggest they can be thrown right into the natural environment, but the results of this most recent study suggest otherwise.

The researchers suggest that standards need to be developed for compostable, biodegradable and oxo-biodegradable materials, such as clearly outlining appropriate disposal and the rates of degradation that can be expected.

The lack of consumer education about the differences between compostable, biodegradable and oxo-biodegradable materials and where to properly dispose of them, coupled with a lack of facilities to deal with their decomposition, further challenges the notion that these products are better for the environment.

But that should not be the end of the conversation. We need to challenge the single-use product model itself.

Will we save the Earth with a better kind of disposable bag? SINGLE-USE vs REUSE

As resistance to the plastic epidemic swells and cities and countries carry out bans against single-use plastic products worldwide, we need to carefully consider the implications of this research study. At the heart of the issue remains a key question: is the single-use, throwaway model sustainable in the first place?

“The problem is not just plastic: it is mass disposability. Or, to put it another way, the problem is pursuing, on the one planet known to harbour life, a four-planet lifestyle. Regardless of what we consume, the sheer volume of consumption is overwhelming the Earth’s living systems.” - George Monbiot, We Won’t Save the Earth With a Better Kind of Disposable Coffee Cup

Last year, someone tweeted at Starbucks to request they replace their plastic coffee cups with cups made from corn starch. This tweet was retweeted over 60,000 times before being deleted when someone raised a big red flag: those who were supporting this call failed to consider the environmental impacts of producing corn starch. As it turns out, an enormous amount of land needs to be cleared to grow it, displacing food production. Growing corn is also notorious for causing soil erosion and requires heavy use of pesticides and fertilizers.

At this stage in the game, it might be beneficial for us to carefully consider what comes after plastic. The impacts of growing and harvesting raw materials, producing the single-use item in a factory and shipping it all over the world just so someone can use it once and throw it away needs to be picked apart and examined.

Humans living in capitalistic societies have a tendency to unleash products on the world without giving much thought as to, you know, whether or not there are facilities available to properly deal with that compostable bag. Or effective ways to collect these single-use items in the first place - technically we have recycling facilities for plastic bags, and yet plastic bags continue to find their way into the ocean. So clearly it’s not just a matter of infrastructure.

Is the problem with the material, or with a model of consumption that relies on disposability and the infinite production of stuff?

“People have to buy less. Our economy is based on endless growth, endless production of what our landfills tell us is basically junk. The stuff wouldn't be in them if it wasn't junk…our economy is already failing us in the way it messes up the planet in the service of all this crap. The cycle just keeps going: manufacture, consume, discard.” Daniel Hoornweg, Canada’s Dirty Secret

Perhaps models that privilege reuse over single-use are a bigger part of the solution than simply pumping out a “better” kind of disposable product.

Katrina Mcguire’s  Zero Waste Station at Withrow Market saved over 1,000 single-use items from being used & discarded in summer of 2018 (534 cutlery, 311 plates, 150 bowls & 59 cups)

Katrina Mcguire’s Zero Waste Station at Withrow Market saved over 1,000 single-use items from being used & discarded in summer of 2018 (534 cutlery, 311 plates, 150 bowls & 59 cups)

Reuse stations like the one launched at Toronto’s Withrow Farmers’ Market last year might offer a solution for small community events. West Ham United and London Stadium launched a #PassOnPlastic campaign by implementing a reusable cup service, saving 20,000 single-use cups from use in just one game (Toronto has a similar, smaller scale service called Dream Zero for reusable cups at events).

In terms of bags, Boomerang Bags Toronto takes unwanted textiles and upcycles them into reusable bags that are meant to circulate around the community - take a bag, leave a bag kind of thing. This project disrupts two waste streams in one go: textile waste and plastic bags. Canada has virtually no textile recycling facilities and 85% of unwanted textiles end up in landfill every year (81 lbs of textiles per person in North America). Rather than extract raw materials to produce single-use bags and ship them all over the world, why not set up local reuse centres that create items like Boomerang Bags for their community at scale?

Boomerang Bags Toronto takes unwanted textiles and turns them into reusable bags meant to circulate around the community. They teach people valuable sewing skills while reducing textile and plastics waste.

Boomerang Bags Toronto takes unwanted textiles and turns them into reusable bags meant to circulate around the community. They teach people valuable sewing skills while reducing textile and plastics waste.

As George Monbiot says in his article We won’t save the Earth with a better kind of disposable coffee cup, the corporate, profit-driven system has never encouraged us to look beyond the materials and challenge the ideology of consumption itself. Before we start producing and distributing every single-use product in biodegradable and compostable materials, it might behoove us to look at the devil in the details: infinite growth on a finite planet is an impossibility, whether you’re consuming 160,000 plastic bags per second or 160,000 compostable bags per second.

Until we sort all this out, maybe stick to carrying your reusable bags (and you can take it one step further by carrying a Zero Waste Kit).


This is a guest blog from @itsahashtaglife – blogger, social media manager and content creator for non-profits and charities in Toronto. She takes the tools and techniques of traditional digital media marketing and applies them to organizations working hard to shift our world into a new story – one that is more sustainable and supportive of people and the planet.