Can nature deal with our double-edged plastic sword?

In the modern age, plastics are ubiquitous and invaluable. Never before has the world had access to a resource that was this versatile, while also being dirt cheap. On the flip side, plastics are difficult to degrade and can accumulate in the environment, causing problems that may become impossible to work around. Prof. dr. Willie Peijnenburg explains the problems and how to make our efforts at tackling them more effective.

Recent discovery

In a recent study, Peijnenburg showed that microplastics can infiltrate roots of several plant species. It feels a bit late to only learn about potential risks after these chemicals have become widespread in the environment. “In the future, we could for example discover that these molecules bind nutrients, rendering plants unable to use the building blocks they need”, he explains. Still, it is likely that other mechanisms that may exist will not become clear for a while. Should we have investigated them sooner, prior to contamination of unintended places?

Learning from the past

Besides microplastics, he also investigates other possible contaminants, such as nanomaterials (used in many manufacturing processes) that became more widely applied decades ago: “Back then, a parallel was drawn to genetically modified organisms, as these were already in production when knowledge on their risks finally emerged. With nanomaterials, governments were wary to not let these problems develop again”.

With plastics and the molecular components they shed, a situation similar to what happened with GMOs seems to have taken place. We now know that, over decades, plastics break down into molecule-scale bits that nature has never seen before. “And now, we have arrived at the point where it is virtually impossible to revert the pollution due to the sheer amounts already on the ocean floor”, Peijnenburg explains, since most plastics sink to the bottom instead of staying afloat.

Prof. dr. Willie Peijnenburg is Project Manager and Scientific Coordinator at the Laboratory for Ecological Risk Assessment, which is part of the RIVM (the Dutch CDC). His research focuses on various sources of contamination, but a recent publication showed that plant roots can take up microplastics. He is also Professor by special appointment of Environmental Toxicology and Biodiversity at Leiden University. (photo: Leiden University)

What to do about this?

Peijenburg is eager to explain a common misconception. “When it comes to regulations to lower the amount of plastics we use”, he argues, “we often make the mistake of not investigating the full picture of environmental impact. In 2016, the Dutch government started enforcing mandatory payments for plastic bags in shops. This cost aimed to decrease single-use of plastic bags and stimulate using a cotton or paper ones. The image of this intervention is good, but a cotton bag only becomes better than using plastic bags after years and years of use. And that’s without washing the bag!”. Ultimately, this may well end up giving no net benefit, or even increasing different kinds of pollution.

Despite their reputation, the introduction of plastic materials has significantly improved the environmental impact of many situations. In many situations, they have replaced other more harmful materials such as metals. According to Peijnenburg, we should always consider both positives and negatives when judging the effect of changing one of our behaviours, even if one of those may be slightly harder to visualise. “Resistance against regulations that could have been truly effective arises on a regular basis, while more convenient but less helpful solutions are applauded”. Use of plastics is always two-sided and sometimes the most ‘conscious’ and helpful choice may not be the most obvious one.

Finding a balance

Besides weighing both sides, Peijnenburg stresses that we should not await consensus on toxicity: “The general philosophy is that we should not place the burden of possible downsides on following generations, harmful or not. So, we should value plastics for their unique and broad properties by using them responsibly where beneficial, while continuously considering cost versus benefit and optimising the ways in which we use them”.


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