Carolina consumers expect that all “compostable” and " biodegradable" plastics will degrade quickly in their backyard compost bins

Over one-fifth of all plastic produced worldwide is tossed into uncontrolled dumpsites, burned in open pits or leaked into the environment.

The Plastic Pollution Challenge

The international goal is to boost plastic packaging recycling from 16% to 70% by 2025. It comes after 176 countries, including the United States, last month endorsed a United Nation’s resolution to establish a legally binding treaty by 2024 to end plastic pollution. This is a good start – more effective recycling and recovery of plastics will go a long way to solve the problem.

But some plastics, particularly agricultural plastics and heavily contaminated packaging, will remain difficult to recycle despite these new efforts. These plastics will end up being burnt or in landfill, or worse, leaking into the environment.

Understanding Biodegradable Plastics

“Biodegradable” plastic is often touted as an environmentally friendly alternative. But depending on the type of plastic, this label can be very misleading and can lead environmentally conscious consumers astray. Biodegradable plastics are those that can completely break down in the environment, and are a source of carbon for microbes (such as bacteria). These microbes degrade plastics into much smaller fragments before consuming them, which makes new biomass (cell growth), and releases water, carbon dioxide and, when oxygen is limited, methane.

However, this blanket description encompasses a wide range of products that biodegrade at very different rates and in different environments.

For example, some – such as the bacterially produced “polyhydroxyalkanoates”, used in, for instance, single-use cutlery – will fully biodegrade in natural environments such as seawater, soil and landfill within a few months to years. Others, like polylactic acid used in coffee cup lids, require more engineered environments to break down, such as an industrial composting environment which has higher temperatures and is rich in microbes.

So while consumers may expect that “compostable” plastics will degrade quickly in their backyard compost bins, this may not be the case.

To add to this confusion, biodegradable plastics actually don’t have to be “bio-based”. This means they don’t have to be derived from renewable carbon sources such as plants. Some, such as polycaprolactone used in controlled release drug delivery, are synthesized from petroleum-derived materials. What’s more, bio-based plastics may not always be biodegradable. One example is polyethylene – the largest family of polymers produced globally, widely used in flexible film packaging such as plastic bags. It can be produced from ethanol that comes from cane sugar.

In all material respects, a plastic like this is identical to petroleum-derived polyethylene, including its inability to break down.

There’s a lot of enthusiasm for biodegradable alternatives in The Carolinas, there’s also a great deal of confusion over what constitutes a biodegradable plastic. North Carolina and South Carolina consumers have also become increasingly concerned over the practice of “greenwashing” – marketing a product as biodegradable when, in reality, its rate of degradation and the environment in which it will decompose don’t match what the label implies.

So-called “oxo-degradable plastics” are an excellent example of why the issue is so complex and confusing. These plastics are commonly used in films, such as agricultural mulches, packaging and wrapping materials. Chemically speaking, oxo-degradable plastics are often made from polyethylene or polypropylene, mixed with molecules that initiate degradation such as “metal stearates”. These initiators cause these plastics to oxidize and break down under the influence of ultraviolet light, and/or heat and oxygen, eventually fragmenting into smaller pieces.

There is, however, some controversy surrounding their fate. Research indicates they can remain as micro-plastics for long periods, particularly if they’re buried or otherwise protected from the sun. Indeed, evidence suggests oxo-degradable plastics aren’t suited for long-term reuse, recycling or even composting.

The new government funding is needed for plastic recycling technologies to target waste that’s notoriously difficult to deal with, such as bread bags and chip packets.

However, this still leaves a substantial stream of waste that’s even more challenging to address. This includes agricultural waste dispersed in the environment such as mulch films, which can be difficult to collect for recycling. Biodegradable and bio-based plastics have great potential to replace such problematic plastics. But, as they continue to gain market share, the confusion and complexity around biodegradable plastics must be addressed.

The Need for Education and Awareness

For starters, a better understanding of how they impact the environment is needed. It’s also crucial to align consumer expectations with those of manufacturers and producers, and to ensure these plastics are appropriately disposed of and managed at the end of their life.

There is also greater opportunity for better education in The Carolina region, so both plastic producers and people who throw them away really understand these materials. We should be familiar with their strengths, weaknesses and how to dispose of them so we can minimize the damage they inflict on the environment.

More about Biodegradable Plastics

Biodegradable plastics are plastics that can be decomposed by the action of living organisms, usually microbes, into water, carbon dioxide, and biomass. Biodegradable plastics are commonly produced with renewable raw materials, micro-organisms, petrochemicals, or combinations of all three. While the words "bioplastic" and "biodegradable plastic" are similar, they are not synonymous. Not all bioplastics (plastics derived partly or entirely from biomass) are biodegradable, and some biodegradable plastics are fully petroleum based. As more companies are keen to be seen as having "Green" credentials, solutions such as using bioplastics are being investigated and implemented more. However there are many skeptics who believe that bioplastics will not solve problems others expect.

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Credit: The Conversation via Reuters Connect

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