How dangerous are microplastics? And other questions about these small pieces of plastic have been answered

They’re in the air, water, and even your body: microplastics. Most of these tiny pieces of plastic, less than 5 mm in size, come from car and truck tires in the Netherlands. We asked what do you want to know about this?

Your questions will be answered by Professor of Environmental Toxicology at Leiden University Martina Vijver. She conducts “living laboratory” research on the effects of small pieces of plastic on our environment. We also spoke to toxicologist Emma Casteel, who is conducting research into the effects of microplastics on our health at Utrecht University.

1. Why can’t microplastics be broken down?

“Microplastics are made from regular plastic, which we’re all familiar with,” says Vijver. “Because large pieces of plastic are weathered by sunshine and rain, for example, at a certain point you end up with smaller and smaller pieces.”

“Those little pieces of plastic can be broken down. This happens very slowly, taking decades. This is because of the large amount of plastic we have made, and because there are only a few microorganisms that can do something with it.” “Plastic is not a food source for most animals, plants and fungi,” she explains.

“You see that microorganisms that can handle plastic, for example, live in large garbage dumps. There the microorganisms break down the plastic into small particles or molecules that you can no longer see or measure. And then we can no longer see or measure them.” “It’s not about microplastics but about nanoplastics.”

Nanoplastic toxicologist Castell knows that the smaller the particle becomes, the slower it decomposes. “In addition, it has become difficult for researchers to measure the very small nanoplastics that end up in the environment. We don’t actually know if they will degrade in the foreseeable future.”

2. How dangerous are microplastics?

“Microplastics are found all over the world: in the depths of the oceans, on the tops of high mountains, and even in places where humans don’t live,” says Vijver. “This shows that the particles are widely dispersed and very persistent: they do not decay quickly.”

“Even if we stop making and using plastic now, those particles will still be around for future generations. This is bad for future generations, regardless of the additional risks of microplastics.”

Little is known about the dangers of microplastics to our health. “People immediately think: ‘Am I going to get some crazy disease from microplastics?’ But that’s impossible to say yet,” says Vijver. “There are many studies on this, but one study says yes, microplastics are harmful, and the other study says no.”

3. What effect do microplastics have on our food?

“Microplastics are found in the soil, in the air, in the water, and therefore also in our crops and in the animals we eat. We simply excrete the vast majority of microplastics that enter our bodies through our food,” explains Vijver.

“This is also evident from the analysis of our wastewater. Thus, microplastics may not belong in our food and in our bodies, but it is still not clear exactly what effect they have on this.”

4. Why do microplastics affect your health?

“Fortunately, our intestinal system is smart enough to reject most microplastic particles rather than absorb them.” But according to Vijver, there are small pieces that can still penetrate your body further. “Scientists see that these particles end up in the brain, liver or in the placenta during pregnancy, for example.”

“These small particles can cause harm, but we don’t know at all what kind of harm it is and how severe it is. If you compare microplastics to pesticides or antibiotics or plasticizers, the harm is much more pronounced and more direct with these types of things.” But according to In her opinion, that doesn’t mean damage can’t be done in the long term. “This is not well known yet.”

“It is known that the smaller the particles, the more harmful they become. Because then it becomes more difficult for your body to protect itself from them.”

Castell adds that a lot of research is currently being done on the impact of both microplastics and nanoplastics on our bodies. “More and more evidence is emerging that nanoplastics definitely have an effect on our bodies, but the harm they cause is still under investigation.”

5. Is it possible to filter microplastics from the air in cities and along highways?

“There are different types of algae, as you know from the forest, that can filter microplastics out of the air for us,” explains Vijver. “The moss has a large surface area that absorbs air like a kind of sponge in order to capture carbon dioxide. This has the side effect that it also absorbs other molecules from the air, such as microplastics.”

“But we removed a lot of moss and trees with a cleansing effect from the cities.” So, according to them, you will have to filter using synthetic filters. “Then you need large facilities, but there is often little space for them in cities. Or there are other reasons why politicians don’t choose these types of filter installations.”

6. In what ways can microplastics be found?

Research conducted by RIVM shows this Rubber car tires leave behind microplastics. “RIVM looked at how to keep microplastics out of the environment, and then they came to the conclusion that car tires could be made differently so that they would wear out less quickly,” says Vijver.

“It doesn’t matter what type of roads you drive on, you can find microplastic particles on all roads. But the amount depends on how quickly your tires wear out. If you speed through corners or brake hard, your tires wear out more.” “And then you get more molecules,” says Vijver.

There is also a difference between roads in, around and outside cities. “If you drive through the city, the plastic particles in car tires are often washed into the sewers by rainwater. The sewers are not the answer, because there too it is difficult to remove the particles from the water, but there you have sedimentation tanks where some of the plastics settle out.”

“While you’re out of town: the particles simply disappear on the side of the road. And then: in the soil, in the groundwater.”

7. Is it possible to completely ban microplastics in products that end up in sewers?

Castells believes that enforcing a ban on the use of microplastics in products would be very complicated. “Microplastics end up in our sewers in different ways. Not just by breaking down plastic packaging, but also through products that contain microplastics. Consider, for example, the scrubs you use in the shower or the toothpaste you spit out and then In the sewer basin.”

The European Union passed a law in 2023 banning manufacturers from selling products with added microplastics. But there are many other ways microplastics end up in sewers. Castiel knows that washing your synthetic clothes is also guilty of this.

So Vijver believes that a complete ban on microplastics is almost impossible, because we are only now becoming aware of the fact that they are everywhere. “Microplastic particles are everywhere. Moreover, they are not easy to remove from products. I believe that not only consumers, but also producers have a role to play in raising awareness about the use of plastic.”