Today, 8 June, is World Oceans Day, which in 2018 is focused on "preventing plastic pollution and encouraging solutions for a healthy ocean."

According to the UN, plastic pollution is causing tremendous harm to our marine resources:

  • 80% of all pollution in the ocean comes from people on land.
  • 8 million tonnes of plastic per year ends up in the ocean, wreaking havoc on wildlife, fisheries and tourism.
  • Plastic pollution costs the lives of 1 million seabirds and 100,000 marine mammals per year.
  • Fish eat plastic, and we eat the fish.
  • Plastic causes $8 billion in damage to marine ecosystems each year.


These are compelling numbers. As a consumer, and as someone who works in environmental consulting, I am very conscious of my household’s contribution to the toll we all take on our oceans through our everyday activities.

In my household, we’ve been trying to reduce our overall reliance on plastic bags and packaging use. For us, this means shopping with reusable shopping bags and mesh fruit and vegetable bags, and making every effort to buy goods with less packaging, or packaging that is ‘friendlier’ to the environment. The stockpile of old supermarket bags stored at home has slowly decreased as we find new ways to re-use them, taking baby steps as a household towards the road to being more conscious as consumers.

One area where we haven’t entirely stopped using plastic is bin liners. On a recent trip out to emptying the garbage bin from the kitchen, I was interested to see that a new brand of plastic bin liners had made it into the kitchen cupboard. While made of plastic, they were wrapped in a nice green paper package with the promise that the bags were “Totally Degradeable.” Naturally, the scientist in me kicked in.

It’s well known to the public that light plastics are harmful to the environment as they don’t degrade quickly, they create issues for our environment (particularly our marine areas), and are a ubiquitous problem.

In this article, I look at one of the key challenges we have personally faced in becoming a household of conscious consumers – products that claim to be totally degradeable. Are they really having a positive impact on our environment and our oceans?

Totally degradeable – the right choice for a conscious consumer?

Light plastics are also difficult to recycle and have limited value as a recycled material if that ever occurs. Some of Australia and New Zealand’ largest supermarket chains have recently announced moves to charge for the use of single-use plastic bags, and in some cases committed to reducing plastic packaging on fruit and vegetable products, so it’s great to see that there’s a growing awareness that we should try to do something about limiting their use.

“Totally degradeable”, however, is an interesting term to use for plastic.

What does degradeable mean?

Degradation can mean a number of things. It could mean the fragmentation of plastic into smaller and smaller particles, leading to the creation of microplastics, sooner. More on microplastics later. It could also mean that this manufacturer had found a way to make plastics decompose fully; that being the ability for plastic in the environment to be used or converted by microorganisms into elements that are normally found in nature. Exciting, as this is one of the key issues of plastic – we don’t know of too many organisms that are able to do this naturally, leading to a significant accumulation of plastic that doesn’t go anywhere, anytime soon, takes hundreds of years in the meantime to decompose. Either way, I had to know more.

Plastics are made of up long chains of organic polymers, which effectively means they are long strings of chemicals made up of a similar set of repeating units. In this case, it seemed that an additive had been introduced to the plastic which made it ‘oxo-biodegradable’. According to the manufacturer’s website, field trials revealed an enhanced speed of fragmentation – large bags become smaller pieces quickly. It’s argued that the additive drives faster oxidation in these plastics, leading to increased speed of the degradation of large chained plastic polymers to shorter chained polymers. All plastics exposed to UV and air do this, but usually at a very slow rate. The manufacturer pointed out that shorter chain plastic polymers, in certain lab scenarios, have been shown to biodegrade. 

The downside of increasingly fragmented plastics

I asked myself: in the environment, outside of a lab, is it actually possible to see biodegradation at a time scale that is beneficial? 

If not, the creation of increasingly fragmented plastics and microplastics could actually result in even worse environmental outcomes. Increased concentrations of microplastics have been shown to cause issues to fish and other marine life as they get mistaken for food or otherwise ingested; and there is growing concern that plastics, or components of plastics, may be entering the human food chain as a result.

At an hour close to midnight (and completely distracted from my initial task which was to simply replace the bin liner), I found it; The European Commission’s recent literature review of the impacts of the use of oxo-degradeable plastics which you can read here.

It found that there is no dispute with the result that the use of additives enhance the degradation of plastic – it did however, note that this degradation was in fact the fragmentation of plastic into smaller and smaller pieces. In a real-world environment, there are significant doubts (the EC uses the words “not substantiated by evidence”) about the benefits of decomposing small fragments of plastic in a natural environment. There appear to be significant residual concerns about the effects of microplastics in the environment, enough to justify the current EC position, which is to begin the process of restricting the use of the oxo-degradeable plastics in the EU.

Stay vigilant

From a consumer’s perspective, there may be some reasons why you’d want to buy these bags – they may be cheaper, fit your bin the best, or you may prefer the smell, texture or usability of the bag itself. They’re all valid reasons to make the decision to spend your cash on these. 

However, if you’re looking to take a step in the right direction to be more conscious with your purchases (just like my household is), buying these bags because of the sustainability reasons alone isn’t the right choice. It just goes to show that even a person working in the environmental industry can get lured into making a quick and easy decision in the supermarket, and we need to be vigilant in understanding what we’re buying, and why.

Happy shopping.

Karami, A., Golieskardi, A., Bin Ho, Yu., Larat, V., Salamatinia, B. (2017) Microplastics in eviscerated flesh and excised organs of dried fish Scientific Reports, 7:5473 
About the Author
Raymond Chang

Principal- Environmental Science

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