Compostable or complicated? The truth about ‘sustainable’ alternatives
Amidst the growing plastic crisis, a surge of new ‘sustainable’ plastics has emerged. The plastic crisis refers to the overwhelming abundance of plastic products that are created globally; their contamination spans oceans and landfill sites. National Geographic cites that approximately 8 million tonnes of plastic is being washed into the oceans each year, and can take up to 400 years to decompose.
One solution to this crisis has been alternative plastics, which are deemed more sustainable due to their ability to break down, or be produced more efficiently. Over the past decade, supermarket shelves have been increasingly stocked with innovative packaging, all promising a more sustainable future. These range from biodegradable coffee cups to wooden cutlery. Even so, regardless of which form these packages take, countless of these products boldly claim to limit pollution and minimise carbon footprints without proper evidence.
It is clear that many of these alternatives seem too good to be true. That’s because in most cases, they are. For example, polylactic acid (PLA) and oxo-degradable plastics are two alternatives to traditional petroleum-based plastics that have been increasingly branded as green solutions. In reality, both materials have been associated with environmental issues, especially when it comes to their ability to be recycled.
Oxo-degradable plastics are made up of traditional plastic such as polyethylene or polypropylene, which are then combined with metal additives. When exposed to light or heat, this oxo-degradable material fragments and breaks down. This might seem like a benefit at first. However, this fragmentation means that oxo-degradable plastics don't truly biodegrade but instead break into tiny particles known as microplastics. These are particles less than 5 millimetres wide and pose a serious threat to marine wildlife. They are small enough that they are easily ingested by most sea creatures, and then gradually accumulate in animals higher up in the food chain.
The release of microplastics by oxo-degradable plastics is urgent; microplastics are being found all over the world, from the Arctic Sea to the placentas of pregnant women. A report has estimated that the average person consumes about 5 grams of plastic per week! In fact, the effects of oxo-degradable plastics are so harmful that in 2019, the European Union banned oxo-degradable plastics over concerns about environmental damage.
Unlike oxo-degradable products, polylactic acid (PLA) materials have presented a more promising alternative, since they aren’t made from traditional plastic. Instead, PLA is a material made from corn starch or sugarcane and is often used in disposable cups, food cartons, and packaging. Whilst it’s advertised as ‘biodegradable’ by manufacturing companies such as NatureWorks, this is not always the case. PLA requires industrial facilities to be composted effectively, with high temperatures and specific conditions to ensure a proper breakdown of material. The melting temperature of PLA can range between 130 and 180 degrees depending on the method used such as industrial or chemical and must be processed before being broken down.
These facilities that can provide these conditions are scarce. In the U.S, there are less than 200 such facilities, and most American municipal waste systems cannot process PLA effectively . In this respect, there is a limited capacity for recycling PLA, highlighting a more complex solution than advertised. Moreover, the process requires high amounts of energy to reach the minimum temperatures to break down PLA to safe levels, which further highlights the sustainability issues associated with this material.
Crucially, consumers often mistake this compostable tag. Many people assume that the advertised tag means they can compost these products at home or dispose of the product at a landfill site, without realising recycling needs to be enacted professionally.
To make matters worse, even when PLA ends up in standard recycling systems, this material can contaminate traditional plastic recycling streams. Although PLA can look similar to traditional plastics, The National Institute of Health states that it melts at a different temperature. This means that mix-ups between PLA materials and traditional plastics can cause serious issues and potentially end up affecting the recycling of other materials. This means that even biodegradable materials aren’t always suitable alternatives.
These issues with polylactic acid materials and oxo-degradable products are merely part of a bigger problem of greenwashing. Terms such as “biodegradable,” “eco-friendly,” and “compostable” are often used interchangeably, with not enough regulatory checks.
As consumers increasingly push for more sustainable packaging, it’s essential to look beyond the marketing. Items labelled as ‘sustainable’ or even ‘biodegradable’ aren’t automatically good for the environment. In fact, if these labels aren’t properly regulated, where they end up can be just as harmful as traditional plastics. Innovation is important, but we need proper recycling infrastructure and clear labelling so that these new materials don’t backfire. Until then, the best solution may still be the simplest. Reduce, reuse, and critically look at the alternatives.