‘Biodegradable, compostable, eco-plastic’ – but is it better?

Dr Merrin Pearse explains what the terms on your plastic packaging mean and why it’s important to understand them.

Your company has done a plastics audit and now understands where single-use plastics are used along your supply chain. The freight packaging, the shrink wrap on packs of items, the safety protectors on the products and the bags individual products are sold to customers in, have revealed many plastic items that are all made of different types of plastic. So a discussion has now started within your organization about reducing the different types of plastics used to better align with your local recycling services. And whether you work in procurement, facilities management. product design or marketing – you need to know to that you are contributing to your company’s environmental endeavours by more than embracing some multi-syllable words.

Some of your products are used in the outdoors so there may be some leakage of the packaging into the environment. As a consequence of this you start considering the properties of the plastics, know as polymers. Your colleagues are asking how long the plastic will take to breakdown if it enters the environment (or the landfill), the conditions needed for that to happen and what it will finally become.

So begins your journey of discovery into terminology used in the manufacturing and marketing of plastic packaging.

In simple everyday terms what is the basic concept and expectation when someone says an item/product/thing is:

Compostable?
Biodegradable?
Environmentally friendly?

Compostable – to gardeners this would be clear that if they put plastic in with a pile of leaves and other organic matter the plastic would eaten by micro-organisms and turned into safe and natural nutrients in a few months without leaving behind any dangerous chemicals or small pieces of plastic. That compost/humus would be safe to use to grow food in.

Biodegradable – equivalent to compostable however whereas compostable refers primarily to solid materials, biodegradable also includes the decomposition of liquids. To say something is biodegradable should mean it breaks down or decays naturally without any special scientific treatment. Of course in nature some things biodegrade in a few months like a leaf or many years like a tree as it rots. It is therefore true that most plastics are biodegradable – it is just that it might take them 100 or even 1,000 years to decompose.

The term ‘environmentally friendly‘ (or ‘eco-friendly’) has no specific definition, and its inclusion on packaging does not help the user understand what the necessary process is for it to ensure its end of life is not landfill.

So what happens in a landfill to things that are compostable? Do things like leaves or food scraps decompose? Not quickly and in some cases not at all, since inside landfills it is an anaerobic (without air/oxygen) environment unlike a garden compost heap which is an aerobic environment that also has more moisture than a landfill. Therefore compostable products are not designed to degrade in landfills.

So if you buy something that says it is compostable does the mean it will breakdown Well maybe, but it depends on the standard they are claiming it is compostable in terms of. Some of the standards only refer to composting in commercial composters. The temperature of these is often over 60 degrees Celsius and there is a high humidity, so it is not a common situation in nature.

Yes there are many standards, not just for composting, though for a customer it is very confusing as to what the different standards mean in terms of the simple question: Is this plastic going to quickly and safely disappear if left in the outdoors?

Other terms used to describe how a plastic disappears/degrades include:

Bio-degradable (by micro-organisms)
Hydro-degradable (by water)
Photo-degradable (by light)
OXO-degradable (by oxygen)

These terms show that without the prefix the consumer can’t tell what type of conditions are required for the plastic to degrade. It is important that when choosing your products plastic, you need to understand how it degrades best in nature and to inform your customer of what they should do with the product at the end of its life. With the growing awareness around the challenges of recycling different plastics, customers are now expecting producers and retailers to know which local recycling systems are in place that can handle their products. One way to find a recycler for your plastics and other recyclables is via Hong Kong Waste Reduction Website maintained by the Environmental Protection Department.

You might be thinking, what if we use bio-plastic for our products, surely they are better since they are made from plants that are easily grown and therefore we avoid using fossil fuels? This opens up another whole discussion. What is relevant to this article is the following from BAN List 2.0

“Bioplastics and bio-based plastics are made from renewable feed stocks (biomass), like the leftover pulp from harvesting sugarcane. The feedstock however doesn’t determine its compostability or biodegradability, the molecular structure does. Therefore using the word “Bioplastic” doesn’t tell you anything about its performance in the environment, or its recyclability.”

With the information in this article in mind, it might be worth reviewing what product claims you are already making about biodegradability, compostable or eco-friendly. To assist you with an effective review consider these three questions: