2023-11-25 14:08:00
In recent weeks my plastic rain suit has been indispensable once more. And while cycling through the rain, I thought plastic was a fantastic invention. It is light and strong, and keeps you dry and warm. Moreover, my raincoat has those smart zippers under the armpits to prevent you from getting sweaty. It is made of one hundred percent recycled nylon and the previous one (from the same brand) lasted almost twenty years.
However, my raincoat is not completely environmentally friendly. Because this jacket also wears out and leaves traces of microplastic behind. These are tiny plastic particles that are hardly visible to the naked eye. They end up on the street or on the roadside. And there they lie for ‘eternally’. Because like all plastics, nylon is actually too strong. For example, a PET bottle in the forest takes regarding 450 years to completely decompose.
It’s not just my raincoat that wears out. Car tires, fleece sweaters, fishing nets and plastic litter also spread microplastics. It is now everywhere in the soil, floats through the air and floats in the water. Microplastic has even been found in Antarctica and Mount Everest. It is also found in small amounts in our food and drinking water. Everyone consumes an amount equal to half a grain of salt every day. Whether this is harmful to nature or your health – and if so, to what extent – is still unclear.
The accumulation of plastic, or its disappearance
In science fiction stories where the world is succumbing to environmental pollution, microplastic often plays a role. It accumulates in food chains to dangerous levels or causes infertility. A classic science fiction book regarding this is The Sheep Look Up by the British writer John Brunner who was inspired in the 1970s by the ominous reports of the Club of Rome. But also think regarding The Handmaid’s Tale or the grim movie The Road.
On the other hand, there is also science fiction that predicts disaster because all the plastic suddenly disappears. In Ill Wind by Doug Beason and Kevin J. Anderson, for example, a microbiologist develops a genetically modified bacterium to clean up an oil spill at sea. The bacteria appear to eat not only the oil, but also all plastics made from petroleum. The bacteria spread so quickly that no plastic is safe anymore. Your raincoat, your mobile phone, half your car, the sewer pipes, water pipes and the insulating plastic around electrical cables are suddenly food for animals. The chaos is complete when the power and water supply finally fail.
Much imagination is not needed for such a story, because scientists are indeed looking for micro-organisms that eat plastic. These can be useful for recycling plastics and cleaning soil and water from microplastics. And they have already been found. Japanese researchers discovered a bacterium called bacterium seven years ago in the soil around a PET recycling factory Ideonella sakaiensis. That bacteria can break down PET. Fungi have also been discovered that grow on PUR, a polystyrene-eating flour moth and a caterpillar that eats through shopping bags. But eating plastic is painfully slow and often not wholeheartedly. If other food is available, the organisms leave the plastic alone.
More robust and faster versions
Microbiologists are trying to increase the speed. They isolated the enzyme that ‘cuts’ the plastic (Pet-ase) from the PET-eating bacteria. By making small changes to the structure of this enzyme, they try to create more robust and faster versions. There are now PET-ases that cut up a piece of PET within a day. Pet-ase does not yet appear to be immediately useful. In the world of plastics, PET is a relatively easy snack and can easily be recycled in other ways. It is not without reason that this plastic is used for recyclable soft drink bottles. Yet it is also an important step towards micro-organisms or enzyme cocktails that might clean up our plastic mess in a decade.
Then you have to be careful that they don’t devour all the plastic. This is possible with good precautions. Our detergents already contain modified enzymes and they are also used to brew beer and make medicines. Perhaps the greatest risk for a plastic-guzzler lies in nature itself. After all, nothing there is indegradable and everything is food. Eventually, even the toughest heartwood disappears. The longer plastic is left lying around and the more we use it, the greater the chance that a fungus, lichen, bacteria or worm will adapt and start eating plastic. Then, in addition to woodworm or the American ground termite, we also have to combat the pur-biter or the PVC fungus.
Science journalist Marga van Zundert writes every other week regarding inventions and ideas that can make the future brighter. Or will it remain science fiction? Read her here previous columns back.
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