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Are Biodegradable Bags Really Biodegradable?

Updated: Oct 28, 2020

Do Biodegradable Plastic Bags Work?

Once heralded as a state-of-the-art, 'eco-friendly' solution to all our single-use carrier bag problems, biodegradable plastic bags have ostensibly fallen from grace after recent research by the University of Plymouth's International Marine Litter Research Unit revealed that, despite being sold as forward-looking, good-for-the-planet packaging, the majority of biodegradable carrier bags circulating our high streets, supermarkets and outlet stores are still capable of carrying full loads of shopping after being exposed to the natural environment for more than three years[1].

“[Our] research raises a number of questions about what the public might expect when they see something labelled as biodegradable. We demonstrate here that the materials tested did not present any consistent, reliable and relevant advantage... [and] it concerns me that these novel materials also present challenges in recycling. Our study emphasises the need for standards relating to degradable materials, clearly outlining the appropriate disposal pathway and rates of degradation that can be expected." - Professor Richard Thompson OBE, Head of the International Marine Litter Research Unit

The institute's research into the environmental impacts of biodegradable plastic bags - which has been going on for more than a decade - reveals that in defiance of being exposed to the kinds of surroundings they might encounter if discarded as litter, most biodegradable carrier bags still remain functional after being buried or left in marine habitats for more than three years. Of the five different types of biodegradable plastic bag studied (all of which are widely available from high street retailers across the UK), all were still usable; bar the compostable bag which was the only one to fully degrade.

“After three years, I was really amazed that any of the bags could still hold a load of shopping. For a biodegradable bag to be able to do that was the most surprising. When you see something labelled in that way, I think you automatically assume it will degrade more quickly than conventional bags. But, after three years at least, our research shows that might not be the case.” - Imogen Napper, Research Fellow

So, as everyday people; governments, institutions and organisations join forces to continue fighting our war against plastic - a social and moral phenomena which emerged in 2015 and continues to snowball to this day and remaining a plight which crosses both borders and political divides - doubts are now being cast over just how 'environmentally friendly' some forms of biodegradable plastics really are.

The university's research begs the question: can biodegradable products ever be relied upon to offer any realistic solution to our plastic litter problems? The research also raises several other pertinent queries, such as; were biodegradable plastic bags ever truly designed to fully decompose? Can they ever work and if they can't, what are our current and future alternatives to single-use plastic carriers?


Are Biodegradable Bags Compostable? Are Biodegradable Bags Recyclable? Are Biodegradable Bags Better than Plastic Bags?

Are Biodegradable Bags Good for the Environment?


Our Problematic Relationship with Plastic Packaging and Why Biodegradable Plastics Were Created

Up until recently, plastic has reveled in a sort of anonymous ubiquity. Like the air around us, we're so thoroughly surrounded by the stuff that nowadays we hardly notice it. For instance, did you know that today's cars and planes are, by volume, about 50 per cent plastic? And that more clothing is made out of polyester and nylon than wool or cotton? There's even plastic in our teabags; minute amounts of plastic are used to seal the 60 billion bags of tea we Brits go through every year. Add this astonishing amount of plastic to the more obvious expanse of consumer packaging, household products and toys we use on a daily basis and it becomes easy to see how the world produces around 340 million tonnes of the stuff every year; enough to fill every skyscraper in New York City[2].

We've been producing unfathomable quantities of plastics for decades, first passing the 100 million tonne mark in the early 1990s[3]

But, despite our growing concerns over plastic waste, plastic still remains crucial to our modern way of life. Without them, most of our advances in modern medicine; technology and engineering couldn't have come to fruition. More importantly, the plastic boom after World War II helped raise peoples standard of living and now have made many of our possessions more affordable; lighter, safer and stronger[4].

Regardless of these successes, though, someone, somewhere, many years ago came up with the concept of biodegradable plastics. But when did this idea first come about - and above all else, why?

Why Biodegradable Plastics Were First Invented

Biodegradable Plastics were the Key to Creating Plastic Products During a Global Energy Crisis

It would be heartwarming to think that biodegradable plastics were first invented because we cared for our planet; that we wanted to stop these synthetic materials - artificially created chemicals that don't mix well with nature - from polluting and harming the Earth. And whilst to some degree this is true, the primary motive behind the birth of bio-plastics was due to an energy crisis in the mid-1970s and driven by the desire of companies within the plastics industry to continue making products and more importantly to them, their profits[5]. But when were bio-plastics first discovered and how did that discovery evolve so swiftly and extensively to warrant plastic manufacturers to invest so much time, money and energy into biodegradable plastic research and development?

The very first bio-plastic to be made from bacteria was in 1926 by a gentleman named Maurice Lemoigne after he discovered that when bacteria absorb sugars, they produce polymers; much in the same way that when humans eat sugar they put on fat[6]. It wasn't until the middle of the "Me Decade", however, that our modern concept of biodegradable plastics and polymers was first introduced.

In 1975, Japanese scientists discovered two strains of bacteria that lived off the waste products of nylon[7]. Both species; Flavobacterium sp. K172 and Pseudomonas sp. NK87, were identified to be able to digest the man-made plastic molecules thanks to their enzymes - a substance produced by a living organism that acts as a catalyst to bring about a specific biochemical reaction; in this case, to degrade plastic waste.

After their initial studies, the researchers demonstrated that the bacteria's ability to degrade nylon could be replicated in a laboratory setting in just nine days and so began the full-scale research and development of biodegradable plastics.

Vintage plastic advertising posters
For the love of plastic! Some examples of pro-plastic advertising from the 1960s and 1970s.

It was in the midst of these findings being made public that plastic manufacturers interests were first piqued by what the New York Times dubbed in 1985 a "biological curiosity". As global oil prices were on the rise and oil reserves were on the decline, producers of plastic were forced to face the fact that they depended too much on fossil fuels and so needed to think about how they could create their products not just during a global energy crisis but in a future where the sustainability of fossil fuels could be non-existent. As such, plastic manufacturers saw these new biodegradable polymers as a bacteria-based insurance policy, so companies like Marlborough Biopolymers - the first bio-plastics company ever founded[8] - began to invest heavily in bio-plastic R&D; driven by their need to provide new and efficient product solutions. Even as the oversupply of oil in the middle of the 1980s "Greed Decade" put a stop to their initial worries, the more innovative and ambitious plastic manufacturers continued in their research and development.

However, the arrival of biodegradable plastics didn't just come about from the need to solve the problem of how plastics companies could create products during an energy crisis; there were other reasons behind why they were being made and developed too.

Turtle Meets a Plastic Bag in the Ocean

Biodegradable Plastics were Also Born From Our Burgeoning Doubts and Growing Guilt About the Impacts of Plastic on the Environment

Between 1945 and 1980, our unblemished optimism about plastics - once touted as a miraculous material - started to tarnish. Thanks to a growing mistrust in them - a skepticism which began in the early 1960s (after the unsettling revelation that plastics were starting to appear in our oceans[9]) and was compounded by mass concerns in the 1970s that the additives used during plastic manufacturing processes had the potential to negatively impact human health[10] - our perceptions of plastics shifted. They were no longer being seen as unambiguously positive. In fact, for many, their views changed so dramatically about plastics that they took a dislike to the actual word. After the release of the 1968 film The Graduate, plastic became a byword for cheap conformity and superficiality; plastics became synonymous with everything cheap, flimsy and fake[11].

Hence, having acknowledged that there was plastic debris in our oceans; in recognition of the public scares surrounding how plastics can negatively impact our health and despite the global plastics industry trying to encourage worldwide municipalities to collect and process plastics for recycling since the early 1980s[12]; people started to slowly accept that more needed to be done to help combat plastic waste; to look after our planet and to look after ourselves.

But how is it that during the 40 years since biodegradable plastics first came onto the scene, that in 2019 they don't actually work?

Planned Obsolescence, Enforced Disposability and Biodegradable Plastics: Economic Blessing, Environmental Curse

We live in an "upgrade" world, a world where short thrills, exhaustive demands and instantaneous supply reign; where we have seemingly forgotten that everything we do, whether that be at home, work or in other social settings, impacts our planet. Every decision we make counts, but it appears that - particularly in business - we have lost the ability to look beyond our immediate economic and social concerns to see the bigger picture. As such, for the last seven decades, businesses have created practices, policies and procedures that to them are positive but to everyone else - and the planet - are negative: planned obsolescence and enforced disposability.

Planned obsolescence (also known as pseudo-functional obsolescence) is the introduction of superfluous changes in products that don't improve their overall utility or performance. It's a process of purposefully creating merchandise that is, essentially, built to fail, breaks easily or will quickly go out of style so that people want to buy the next exciting - and usually more expensive - product. As such, companies are compelled to produce waste; waste that cannot be reintegrated into nature in productive ways - whether that's their intention or not. And because we have unwisely encouraged manufacturers to do this; to manipulate their products to be used up and discarded for new items in ever increasingly shorter life cycles, it is the opinion of this writer that the practice of planned obsolescence has not escaped the biodegradable plastic bag.

"On a global scale, we have quickly replaced things that have continued and sustained value for newly designed things that are literally created to be valueless[13]" - Leyla Acorogly, UNEP Champion of the Earth, Designer and Sociologist

Go Green - Don't use Biodegradable Plastic Products
Don't judge a book by its cover; just because 'eco-friendly' products look and sound green, doesn't mean to say they truly are.

Despite living in a need-based, "upgrade" culture, we widely assume that due to the widespread increase of green technologies and eco-friendly products, that this "green revolution" is making our world and our lives safer, healthier and overall better. But the reality is that planned obsolescence - the dark side of innovation and an inevitable (and probably necessary) byproduct of capitalism - still effects the green movement by negating its positive impacts on the planet. The faster we improve technology, the more quickly we throw away old products; the result being an exponential increase in waste that is in direct proportion to the rate of progress.

In terms of biodegradable plastic bags, the technologies and scientific know-how behind them has evolved expeditiously since they were first discovered in the early twentieth century. So, it should come as no surprise that as new findings have been uncovered and new products made, old ones were to fall by the wayside. Perhaps, then, this is why the University of Plymouth found that the "biodegradable" plastic bags they studied didn't fully degrade, because the bags they tested weren't the most recently developed kind of biodegradable carrier bag.

Or perhaps the biodegradable bags studied in the institute's research were the results of manufacturers believing that they had achieved the ultimate value engineering with their biodegradable products. Value engineering is a design process that seeks to use as little material as possible in a product while still delivering an acceptable lifespan; a lifespan that the biodegradable plastic bag manufacturers might not have fully tested or felt that no-one else would test. After all, to those concerned primarily on insular economic matters and not the all-encompassing bigger picture, waste is waste; once it's out of sight, it's out of mind.

The recent revelation that biodegradable plastic bags are still usable even after being buried or left at sea for more than three years could also be put down to plastic manufacturers, at present, legitimately not having enough scientific knowledge or the best tools or technologies to hit the nail right on the head. They don't yet have everything they need to create the perfect biodegradable product that will work; that will fully and safely decompose. This is the view of C.K.S Pillai of the National Institute of Interdisciplinary Science and Technology, India, who believes that:

"Polymeric materials with desired physical, chemical, biological, bio-mechanical and degradation properties can now be made with precision to meet various challenges in the environment and biological systems. However, there are several inadequacies in terms of either technology or cost of production. Thus, there is a need to have a fresh look on the design, properties and functions of these polymers with a view to developing strategies for future developments[14]."

In support of Pillai's view, Mel Schlechter, an analyst from BCC Research also contends that a neoteric view of biodegradable plastics needs to be taken in order to create a better product for the future;

"Biodegradable plastics have been around for roughly 20 years, [but] the right ­physical properties for bags are only a recent development. For the biodegradable polymer market to succeed, it is extremely critical that an infrastructure for effective composting be developed. [T]he key to... converting from traditional to ­biodegradable grocery bags becomes an organics recycling question and not a bag question. If bags can be diverted to organic waste programs, either directly or as a carrier for organic waste, then they will quickly biodegrade like other organics, and be ­converted into a highly valuable soil[15]."

Therefore, the aim of bio-plastic manufacturers should be to create biodegradable plastic bags through the long and detailed process of value engineering; all the while looking at the bigger picture of how their scientific, industrious and economic decisions impact the planet. Hopefully then, biodegradable plastics can offer realistic solutions to our plastic waste problems.

So, whether the biodegradable plastic bag debacle has been the unintentional result of plastic manufacturers not yet having the resources or scientific know-how to create effective biodegradable plastics or whether the result of economic and social manipulation, and enforced disposability, at least this 'eco-friendly' product drubbing can act as a synchronistic admonition that can point us in the right direction towards discovering and using new alternatives to biodegradable plastics.

But, what are the alternatives?

Alternatives to Biodegradable Plastic Bags

At present, the best alternatives to biodegradable plastic bags are paper bags - although, as discussed in our blog post "Are Paper Bags Better than Plastic Bags?" these too are not without their environmental influences. Other containers made from all-natural materials such as willow or wicker baskets; cardboard boxes and wooden crates are also great options as they're all organic materials which can easily be composted, plus they're all re-usable.

Speaking of reclaimable items, other great alternatives to biodegradable plastic bags are the reusable items that have either been specifically designed for carrying shopping, for example; produce bags, bags for life, old tote bags, backpacks and wheeled shopping trolleys, or items from around the home that can be repurposed for carrying said shopping in, such as; pillow cases, laundry baskets and homemade carrier bags.

When you really think about it - especially if you think outside the box about what constitutes an eco-friendly alternative to plastics and bio-plastics - there are many items you can use; reuse and re-purpose to replace biodegradable plastic bags until the point comes where they are genuinely biodegradable and good-for-the-planet.

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