Last April 2024, we had the privilege of interviewing Prof. Dick Vethaak, a renowned expert in the field of micro- & nanoplastics. It is with great sadness that we heard about him passing in June 2024. We are honoured to be able to share his insights via the European Science-Media Hub and extend our deepest condolences to his family and colleagues.
What are the particular dangers of microplastic pollution in aquatic and marine environments?
Dick Vethaak: Microplastic contamination of marine and freshwater food chains threatens food safety and security. However, this is also true for terrestrial/agricultural food chains. There is ample laboratory evidence that exposure to micro/nanoplastics can impact aquatic and marine species, albeit at high concentrations. There is limited evidence from nature that microplastics will likely negatively impact pelagic and benthic communities locally.
The plastic particles may cause direct physical or nutritional problems when ingested, and these problems may be exacerbated by the presence of associated plastic additives in the particles or by the presence of other hazardous chemicals that have adhered to the surface. In addition, microplastic pollution could theoretically affect population levels of biodiversity, alter habitats, and interfere with essential ecosystem functions involving ecosystem services that could impact human health. We have introduced a new type of substrate into the environment that could affect the food chain and productivity, potentially altering ecosystem microbial functions. These possible indirect effects deserve much more attention and research.
In the past few years, it has become clear that terrestrial ecosystems, such as soils, are sinks for micro/nanoplastics and, compared to aquatic systems, seem more susceptible to plastic pollution, including their impacts on soil properties, animals, plants, and microorganisms.
Microplastics are now ubiquitous in the environment, and some studies have found microplastics in the human body – what do we know about the potential risks this has for human health?
Dick Vethaak: To date, there is simply insufficient data and knowledge to assess human health risk properly. Nonetheless, the potential health effects of micro/nanoplastics are becoming more evident. This conclusion is based on animal and cellular model studies, as well as epidemiological studies, which suggest that microplastics and nanoplastics may have adverse effects on various aspects of human health. Perhaps the most compelling evidence is the association with the particulate air pollution that kills millions of people worldwide yearly. It is now becoming clear that car tire particles and other plastic particle dust is a component of particulate air pollution and therefore could likely contribute to this crisis.
Our health is likely to be affected by micro/nanoplastics, however, the extent of that impact is still unknown. To answer this question we need to answer the following questions: how much plastic is in the body and where does it go? Are the plastic particle doses in blood and tissues sufficiently high enough to trigger or mediate responses leading to diseases? We need to establish dose-response relationships. This information is crucial for an adequate risk assessment.
Why are there knowledge gaps on the impacts of microplastics on human health and why is detecting and quantifying this so difficult?
Dick Vethaak: Detecting micro/nanoplastics in humans is difficult because we lack the technology and methods to detect, quantify and characterise plastic particles in the body. It is important to realise that we are dealing with a new class of highly complex contaminants. To tackle this, we need to refine analytical technology and analysis, using complimentary methods, to detect and characterise the smaller micro- and nanoplastics in the body on a large scale. In addition, we need to exclude as much as possible the background levels of plastic particle contamination, largely due to the aerial deposition of micro/nanoplastics contaminating the samples during sampling, pre-treatment and analysis. Currently we use control blanks to correct for background contamination, which is a generally accepted procedure in analytical chemistry, but certainly not ideal. Mirco/nanoplastics are everywhere, even in a clean air lab room or operation room!
Recent studies report quite high micro/nanoplastics levels in body liquids (e.g. blood) and tissues. This is maybe not so surprising, because we are long-lived exposed to these particles, and because of their high persistency they could accumulate to higher levels. Nonetheless, we are only now seeing the tip of the iceberg: we are just beginning to open the world of nanoplastics, which are more hazardous than microplastics!
There have also been many diseases and syndromes affecting the gastrointestinal tract, immune system, cardiovascular system, brain, and reproductive organs in recent decades that are relatively unexplained; therefore, micro/nanoplastics may play a part in causing or exacerbating these conditions. To shed light on this, amongst others, human experimental and epidemiological studies are needed. We also need a better understanding of the interaction of plastic particles at the cellular and tissue levels, and to discover the role of the changing properties of the particles influencing their fate and toxicity.
Eventually, we need to know how plastic particles differ from other ambient particles. Do they have a unique toxicological profile given their persistence, wide size range, and complex nature? Especially in unborn infants and children who are in theory, more at risk from (micro)plastic pollution because their body systems, including their immuno-surveillance system, are still developing. There is a need for more research into the health effects of associated additives and other contaminants, such as pathogens and antimicrobial resistance.
There is simply insufficient data and knowledge to assess human health risk properly. We can expect a first preliminary risk analysis in 2025. To determine the possible relationship between micro/nanoplastics and, for example, chronic diseases and common diseases (allergies, asthma, respiratory diseases, diabetes, neurodegenerative disorders, and cancer), long-term research is required (>10 years), because mechanistic, toxicological and epidemiological knowledge and methods to measure the smaller microplastics and nanoplastics in the body are currently largely lacking.
People are constantly exposed to micro and nanoplastics across their lifetimes and so it is likely that ingested and inhaled plastic particles accumulate in the human body. All plastic produced and left in the environment will eventually degrade into smaller particles (nanoplastics). Because environmental levels are doubling every 10–15 years, there is an ever-increasing risk of micro/nanoplastic ingestion and inhalation. As a result, we must consider our limited scientific understanding against the doom scenario that microplastic pollution will only worsen over time.
There is currently no comprehensive EU law tackling microplastics, although tackling microplastic pollution is encompassed by the objectives of several laws and strategies – do you think EU measures are sufficient? What more could be done, and should this be targeting a consumer or corporate level?
Dick Vethaak: No, certainly not sufficient. And if, there are too many compromises with the chemical and plastic industry… for example the EU ban on primary microplastics, it is incomplete and will still take years before it will be effective.
I am particularly concerned about polymeric paints that contain micro/nanoplastics, which to my opinion, is a highly underrated source. These are used everywhere, from the walls in your house to outside on buildings, roads, water works, ships. They will degrade over time and are designed to be wasted!
We urgently need a system change. We need to identify, stop and replace ugly and bad plastics. The way forward is to reduce the amount of plastic in the system and design circular safe plastics or alternative materials. We also need to inform and educate the public and the younger generations.
I strongly believe that we should look to link plastic pollution with other major crises, including chemical pollution, air pollution, biodiversity loss, and climate change/global warming. Rather than competing for research money, we should be complementing each other. Working together will create synergistic actions to help to mitigate these crises.