'DNA' in plastic pollution can be used to hold manufacturers responsible for its clean-up

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Thousands of marine mammals, reptiles, fish and birds die every year, usually from starvation, after mistaking plastic waste for food. 

The United Nations has described plastic pollution as a global crisis, with microplastics discovered from the deepest oceans, to near the top of Mt Everest.

So what if there was a way to trace plastic back to its manufacturer, and even to hold them responsible for its clean-up?

There's now an emerging area of technology that makes it possible to embed a traceable code, which researchers have likened to plastic "DNA", into plastic polymer. 

In a recent paper published in Polymer Chemistry, researchers have rallied the polymer-chemistry community to work towards embeddable codes for plastic, that can be read on small handheld devices in the field, and ideally even on mobile phones. 

"Currently, to read out a code by itself requires multi-million-dollar equipment and specialist, physical chemists," said Christopher Barner-Kowollik, a co-author on the paper and macromolecular photochemistry researcher at the Queensland University of Technology (QUT).

"What we are proposing is, we need either a small handheld device or even a mobile phone [to read the code]."

And that could have some powerful implications.

Firstly, say a whale washes up on a beach with a gutful of plastic. Or another turtle is found with a straw lodged in its nostril.

The code — which could be embedded at either the plastic pellet stage or the product moulding stage, or both — would allow the plastic to be traced back to the manufacturer or the retailer.

There's potential to shame plastic manufacturers, or retailers using plastic products, into doing more to curb their waste. 

"You could take each piece of plastic [in a dead animal], scan it, and say, 'this was produced by producer X, this Y', and you could almost have a percentage breakdown of who ultimately was responsible for the death of that animal," Professor Barner-Kowollik said.

But ending the anonymity of plastic waste is really only the first step. After all, in many cases — soft-drink bottles, chip packets, retail packaging — we already know where it comes from.

So the researchers have issued a "call to action", for chemists, social scientists, and legal experts to work together, to come up with a legal framework, in tandem with plastic-tracing technology, that makes the manufacturers of a product responsible for its entire life cycle.

In that framework, embedding traceable code into plastic simply makes it easier to enforce.

"Thinking about how can we use this technology to build a new legal framework to hold manufacturers to account in their production of plastics and the decisions they make around that is key," said Hope Johnson, paper lead author and a socio-legal researcher from QUT.

Usually called an Extended Producer Responsibility scheme, the theory behind it is if a producer is held responsible for the clean-up of their waste, it becomes more economically viable to avoid creating that waste in the first place. 

That can be achieved by the manufacturer, for instance, replacing single-use with reusable products, charging a container deposit fee, and rolling out networks of container collection stations (where consumers can recoup the fee).

"It's not just the consumer or waste management groups' responsibility to deal with plastics, it should also fall on those earlier in the chain," Dr Johnson said.

"If it did fall on them more, if there was more of a cost in waste, what we may start to see is a redesign of plastic that would help with things like reuse, recyclability, and the safety of those plastics — it would actually have a whole chain impact if we start to shift towards manufacturer responsibility."

If this all sounds a bit hypothetical, it might be further along the road than we in Australia realise.

In the European Union, Extended Producer Responsibility is already mandatory for waste electrical and electronic equipment (WEEE), batteries, and vehicles.

The European Union is a world leader in moving away from single-use plastics, said Helen Millicer, a sustainability consultant and director of One Planet Consulting, who wasn't involved with the paper.

"The EU Commission is setting increasingly stringent targets for products and packaging — for eco-friendly design, recyclability, and recycled content," she said.

And this year, the United Nations committed to developing an international, legally binding agreement by 2024 , to "end plastic pollution", which it described as "the most significant environmental, multilateral deal since the Paris [climate] accord".

In Australia, Environment and Water Minister Tanya Plibersek announced a 2040 target for Australia to recycle 100 per cent of our plastic waste.

Most certified "home-compostable" plastics do not fully break down in home compost bins, a citizen science project finds.

A cornerstone of any plan to end plastic pollution is shifting to a circular economic model, where single use is phased out. And a key strategy to achieving that is Extended Producer Responsibility.

This means that tracing technology, alongside legally binding producer responsibility, is going to become necessary.

Ms Millicer said generally the price of recycled plastic is significantly higher than virgin material.

"The premium is almost double, if not triple, depending on the plastic and the market."

And that's not just a factor of supply and production costs, but because demand for recycled plastic is being driven up by brands wanting to meet targets, transition to a sustainable future and craft green images for themselves.

"Brand owners are wanting to move to a low-waste, low-emissions, and highly circular economy."

But high prices can lead to some unscrupulous players passing off virgin plastic as recycled.

"It's very hard, if not impossible, to distinguish virgin from recycled polymer, and so verification systems are becoming important," Ms Millicer said.

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Again, an embedded code in the polymer could put a stop to greenwashing plastic, among other benefits.

Dr Johnson said it could also help to stamp out illegal waste trading, and closer to home, could help clear up the confusion around what does and does not go in the recycling bin.

The next step is to make the code-reading tech affordable and accessible.

"The cost of recycling plastics is the key barrier to any effective plastic recycling scheme," Dr Johnson said.

"So looking at ways to reduce those costs in a more accessible fashion is the key to making it work." 

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