Pollution expert Anders Baun has never been afraid to change track and say no. That is why he is now taking on the huge group of “forever chemicals”—the chemicals called PFAS —which represent one of the greatest environmental challenges of our time.
Professor Anders Baun heads the PFAS Centre, which conducts research into these problematic substances and proposes long-term solutions to the PFAS-pollution problem, which the authorities can implement. Photo: Bax Lindhardt
Thursday 30 April 2026
Miriam Meister
Anders Baun is trained to say no. Not because he wants to be contrary, but because being able to do so is a prerequisite when you leave your field of research to embark on a completely new one. And that is exactly what the DTU professor has done—not just once, but twice in his career.
“Originally, I worked with ecotoxicology and risk assessments in connection with soil and groundwater contamination at landfills. My real expertise is crustaceans and algae and the toxicity of chemicals to them,” he explains.
The first radical change of course came in the early 2000s, when he was a first mover in researching the potential environmental impact of nanomaterials at a time when most people thought it was almost silly to consider the subject a potential environmental problem.
“There was simply no one, including me, who had questioned the safety of such small particles,” explains the professor, who through his work on the subject has created crucial knowledge about how nanoparticles behave and what potential dangers they pose.
Despite his success in the field of nanotechnology, a few years ago he felt a desire to use his skills to tackle a threat from a type of chemicals that the professor had known about for many years but which he—like many others—had misjudged the significance of, namely PFAS.
PFAS is a huge group of man-made “forever chemicals”. Their chemical structure means that they degrade very slowly and accumulate in humans, animals and the environment. Over the past 20 years, the evidence of their harmful effects on humans and the environment has grown enormously.
The seriousness of the issue of forever chemicals struck him deeply he watched the after watching the movie “Dark Waters” in 2020. It is about the lawsuit against two chemical manufacturers that for decades polluted the drinking water at their factories in West Virginia, where they produced the PFAS-based product Teflon.
“I thought: Wow – good thing I don't live there! In the section I head, with 50 scientific staff working on environmental chemistry, chemical risk and groundwater pollution, we subsequently discussed the PFAS challenge and how “someone” should do something about it,” he says.
"I was probably at a point in my career where I couldn't keep saying that “someone” should do something about it. Maybe I should say instead: I'll do it!"
Professor Anders Baun
DTU
Later that year, the European Food Safety Authority lowered the tolerable limit for how much PFAS a person may consume through their diet by a factor of 50 due to proven effects on the immune system, which can, among other things, affect the effectiveness of vaccines in children.
The limit applies to the total intake of four specific long-chain types of PFAS and in 2022 Danish authorities lowered the drinking water limit value for these to only 2 ng/L. This prompted the professor to act:
"I was probably at a point in my career where I couldn't keep saying that “someone” should do something about it. Maybe I should say instead: I'll do it!"
An overview of the many applications in which PFAS chemicals have been used and the properties that have made them so popular. Illustration: Claus Bue
In full swing
At the time, Anders Baun was a professor and head of a very large section. It was therefore not quite as easy as the first time to shift his research focus, but once again it helped to retrieve the essential “no” from his vocabulary.
“Because you can only say yes to something if you say no to something else, as there is limited capacity. Otherwise, you end up not doing what you really want to do—and there is also a life outside of work,” he emphasizes.
Since then, the professor's new field of research has been in full swing.
CV
PhD from DTU in 1999.
In 2011, appointed Professor of risk assessment of nanomaterials, and awarded the prestigious Consolidator Grant from the European Research Council.
From 2025, head of the PFAS Centre, which researches and collects knowledge about PFAS so that we can better prevent, contain and clean up PFAS contamination.
At the time of writing, author of 159 scientific peer-reviewed publications.
Head of DTU Sustain's section for Environmental Contamination & Chemicals, which promotes knowledge about problematic substances in our environment and helps authorities, organizations and industry to identify and minimize the risks associated with these substances.
In 2023, he and eight other experts (including two other DTU professors) were appointed by the relevant Danish authorities to the newly established PFAS Knowledge Task Force. Its purpose was to identify ways to protect people and the environment from the harmful effects of PFAS.
“I probably distinguished myself by being the one on the committee who knew the least about PFAS at the time,” he admits.
On the other hand, his extensive experience with risk assessments of new chemical environmental problems and advising authorities on managing risks made him well suited for the job.
In early 2025, he became head of the new PFAS centre, where experts from DTU, University of Copenhagen, University of Southern Denmark and Aarhus University, with an initial grant of DKK 44 million, are researching the problem and proposing long-term solutions, which the authorities can implement. In November 2025, an additional DKK 45 million was allocated to the PFAS centre from the 2026 National Research Reserve.
It’s probably a little-known fact that daphnia are one of the most important test organisms for exposing the environmental hazards of chemicals. Professor Anders Baun is an expert in studying the toxicity of chemicals and nanomaterials to daphnia, such as this approximately 3 mm long Daphnia magna, which has been kept at DTU Sustain since 1978. Photo: Hajime Watanabe, CC BY 2.5 <https://creativecommons.org/licenses/by/2.5>, via Wikimedia Commons
Tolerated stay
Due to the water- and dirt-repellent properties and chemical characteristics of PFAS substances, they have been used in a wide range of products, from frying pans and popcorn bags to rainwear and firefighting foam. Their widespread use means that they are now found everywhere in the environment.
Denmark has been a frontrunner in cutting off some of the sources of PFAS—initially in 2020 by going alone in the EU with a ban on their use in food packaging, and again last year with a ban on their use in clothing, shoes and waterproofing agents for consumers, as well as by revoking the approvals for a wide range of pesticides containing PFAS active substances.
“But even if we cut off the sources, we have a 30-year legacy or something like that which we need to do something about while we wait,” Anders Baun explains.
As the professor sees it, the enormous spread of PFAS will challenge the usual way of tackling chemical pollution, which is to clean up contaminated areas to avoid harm to people and the environment. Perhaps we should instead prepare ourselves for a kind of tolerated stay.
“When we realize that everything is contaminated with PFAS, decontamination is not a solution—because it is now a general environmental problem that we cannot simply clean up, as the contamination is so widespread. But that does not mean we should give up,” he emphasizes.
"Of course, we must clean up where the contamination is concentrated, and it is possible to do so. And then we need to assess what I have called ”temporary tolerance of presence”. In other words, we need to have a discussion in society: while we, of course, cannot and never should accept that it is there, will we have to tolerate it for a while – and at which levels?"
”The more questions you ask, the more answers you get. You can choose not to ask questions, but in Denmark we fortunately still have a tradition of continuing to ask questions—even if it generates uncomfortable knowledge."
Professor Anders Baun
DTU
Optimistic, despite it all
“I am optimistic against my better judgement. I do not believe that things will get better—unfortunately—in the sense that it is out there and we must deal with it. But I believe we will get better at doing so.”
And he is confident that we are constantly learning more about the problem, partly through the authorities' insistence on more research.
"Because the more questions you ask, the more answers you get. You can choose not to ask questions, but in Denmark we fortunately still have a tradition of continuing to ask questions—even if it generates uncomfortable knowledge," he says.
The professor also takes comfort in the fact that if we crack the code for these forever chemicals, the future looks bright:
“For me, the interest in PFAS is really that they are like a kind of crowbar into all the other environmentally harmful substances, because the effects are so serious, and it is so widespread and terribly difficult, so if we can handle that problem, we can handle the others.”
Facts
About PFAS
PFAS (per- and polyfluoroalkyl substances) is a group of more than 10,000 different man-made “forever chemicals” which, due to their strong bonds between carbon and fluorine, are difficult to break down and accumulate in humans, animals and the environment.
Due to their water- and dirt-repellent properties and chemical characteristics, they have been used in a wide range of products and industrial processes.
Even at low levels of exposure, they can eventually lead to e.g., an increased risk of cancer, reduced fertility, low birth weight, and weakened immune response.
Denmark has three times gone it alone in the EU against the use of PFAS substances in specific products.
The joy of teaching
In the midst of the important work of curbing the spread of and limiting exposure to PFAS in Denmark, he without hesitation gives an altogether different answer when asked what makes a workday a success:
“It's when I've been teaching! I love the interaction with the students and the challenge of getting my points across in a way that motivates them and helps them learn something.”
His joy in teaching was awakened when he started teaching as a PhD student, and his passion for sharing his knowledge with students is still “100 per cent” intact.
“Recently, after a course, I went home and said: “To be completely honest, I am much happier today after teaching than if I had been sitting at my computer doing work”.”
The professor was actually only supposed to teach a couple of classes during DTU Sustain's basic course in environmental processes in the autumn of 2025 for the first time, but he decided to change track:
“I said to the others: You know what, I'm actually going to do most of the lectures myself because it's fun. It's going to be really difficult, and I'll have to spend two days preparing for each lecture. But it just makes me happier,” he says with a smile.
Anders Baun enjoys teaching and loves interacting with students – as seen here, where he, Lærke Gordon Clausen and Frederik Orry Baggers are taking water samples at the Regions' PFAS testing centre in Korsør. Photo: Bax Lindhardt
Important insights
Surprise attack
While some researchers have been calling for action on the dangers of PFAS substances for the past two decades, many have been taken by surprise by how problematic they are.
In 2024, Anders Baun and his colleagues published a scientific article in which they examined research results over time as well as the actions of companies and authorities to uncover what we can learn in hindsight from the early warning signs that were there.
"There are several things about the molecules that have surprised us. So, you can't necessarily point fingers retrospectively when we've only realized “Oh, my god!” later," he says.
The authors describe, among other things, that PFAS substances are insidious because they accumulate much more than they ought to be. This is because all other known chemicals bind to fatty tissue, and their ability to accumulate can therefore be described entirely in terms of their fat solubility.
However, research from the early 2000s showed that PFAS substances, which are both fat-soluble and water-soluble, bind to proteins. This, together with their persistence, mobility and toxic effects, makes this group of substances particularly problematic in both environmental and health contexts.
Another challenge mentioned in the article is the development of “regrettable substitutions” in the eagerness to stop using some of the most toxic PFAS substances, given that the alternatives also turned out to be able to accumulate and be (in some cases at least as) harmful to health.
