Van Duursen researches plastic. What exactly is plastic made of? The toxicologist compares it to a construction project. “Plastic is extremely versatile, which is precisely what makes it so attractive. It’s composed of polymers – think of them as the building blocks of a complex structure. Chemical substances are added to these polymers to make them usable in practice. Examples include plasticisers, hardeners, flame retardants and colourants.”
Microplastics
There are two types of microplastics: primary and secondary. Primary microplastics are deliberately added to products such as chewing gum or cosmetics, to make them look glossy, for example.
Secondary microplastics are created when plastic breaks down: during use, when heated (such as a plastic container in the microwave), or through exposure to sunlight. TNO estimates that 35% of secondary microplastics originate from tyre wear.
How microplastics enter the food chain
Litter is another major source of secondary microplastics. Plastic packaging materials often end up in the environment. Van Duursen explains: “The particles are so small that they’re invisible to the naked eye, which means they spread easily through air and water. They’re absorbed by plants or ingested by fish – which is how they enter our food chain.”
We therefore inhale microplastics or are exposed to them through our diet. “Exposure is unavoidable,” says the toxicologist. But how harmful is this exposure? “It’s difficult to determine exactly how much we ingest, because quantifying it is complicated. Moreover, we have very few reference materials: microplastics can take the form of fibres or fragments, each containing different chemical substances. The number of possible combinations seems endless.”
“Microplastics don’t belong in our bodies”
“How plastic particles behave once inside the human body is also difficult to map,” says VU Amsterdam’s toxicology professor. What we do know is that they can be detected. “Using chemical analyses, we can measure polymers. That’s something we do in our department, Environmental Health & Toxicology. We also find plastic particles in the human body – in the lungs, intestines, tissues, blood and even in the brain. And they do not belong there.”
Although the effects of microplastics inside the body are not yet fully understood, it’s reasonable to assume that health risks exist, according to the professor. Van Duursen sums up several research findings. “Our immune system recognises microplastics as foreign entities and attempts to remove them. This can trigger inflammatory responses. At the cellular and tissue level, particles may cause damage. There are also indications of potentially negative effects on the cardiovascular system.”
Microplastics and fertility: “The puzzle is far from complete”
Microplastics can also penetrate reproductive organs and the placenta. “We know that some of the chemical substances that leach from plastics can disrupt hormonal systems. These substances may have adverse effects on female fertility. But when it comes to the plastic particles themselves, we still know very little,” Van Duursen qualifies.
Why is this the case? “The effects of plastic particles are difficult to demonstrate because reliable methods of measurement are still lacking. Moreover, many existing studies are too small. Establishing cause and effect is therefore challenging. There are still many unanswered questions. More and more pieces are falling into place, but the puzzle is still far from complete.”
Plastic particles and “sensitive life stages”
“As a toxicologist, I’m interested in external influences on our health – particularly the effects of particles during so-called ‘sensitive life stages’: before birth and in children who are still developing,’ says VU Amsterdam’s toxicology professor. “The effects may be permanent and could even be passed down to future generations. If my research and expertise can contribute to better understanding, that’s valuable.
“Preventing illness benefits not only individuals, but also society as a whole,” Van Duursen continues. “This is more relevant than ever, because plastic production continues to increase. Problems may accumulate over time. Change is needed now.”
Breaking down chemical substances safely
What’s needed to bring about change? First and foremost, stricter legislation, according to the toxicologist. “We see this with BPA restrictions, for example: once stricter regulations were introduced, BPA levels in urine decreased. But banning chemical substances one by one is like mopping the floor while the tap is still running. Chemists work faster than toxicologists, so alternative substances are quickly introduced. A better approach is to think at the very start of the production chain: how can we design a product that’s safe?”
In addition to stricter and more comprehensive legislation, consumer awareness is essential. “People have a clear image of plastic soup and plastic litter. They also need to realise that plastics can break down and end up in our food and our bodies,” Van Duursen emphasises.
“Our behaviour of consumption generates large amounts of plastic particles. Throwaway culture has become normalised. Many microplastics consist of fibres released from clothing. We should ask ourselves: do we really need new clothes so often?”
"It's never too late to make sensible choices"
Taking steps to reduce plastic yourself
Think carefully about what you buy, eat and drink, advises Van Duursen. “Stop buying things from cheap Chinese web shops, where responsible production is less well regulated. Choose seasonal vegetables instead of papayas wrapped in plastic, shipped from faraway countries.”
Other practical recommendations that you can do at home:
- Don’t heat food or drinks in plastic containers in the microwave; transfer them to glass or ceramic containers instead.
- Chemical substances and microplastics also accumulate in household dust. Children regularly ingest dust and are therefore highly exposed. Make sure children wash their hands regularly.
- Ventilate your home well: chemical substances can off-gas from electronic devices into the air.
In short, the potentially harmful effects of microplastics can be reduced through a combination of research, legislation and consumer awareness. Van Duursen concludes: “If you understand the potential dangers, you can make better choices. If we do that collectively, we can keep our plastic use under control and protect our health – also over the long term.”
