In the US, a wave of litigation concerning the effects of PFAS chemicals on humans is underway. Some experts talk about a problem comparable to asbestos. You and a group of scientists have warned about PFAS recently. How dangerous are these chemicals really for humans?
The question of whether PFAS is toxic or not is, of course, central to legal disputes. It has been shown scientifically that PFAS are chronically toxic and detrimental to the liver and kidneys, besides other harmful effects. This was done by epidemiological studies in the US but also in other locations, for example, Italy. In the area of Parkersburg, West Virginia, USA, tens of thousands of people have been exposed to high concentrations of PFAS in their drinking water. These people had significantly higher rates of cancer, thyroid diseases, chronic inflammatory bowel diseases, reduced sperm count and other diseases.

These cases you mentioned were people who lived close to industrial plants producing PFAS. If I live far away from such places, am I safe?
The groundwater near a manufacturing plant is just one possible indirect source of contamination. In South Baden, Germany, just across the border from Switzerland, some fields and the groundwater underneath are heavily contaminated with an elevated level of PFAS. Here the origin of the PFAS is that, years ago, they were fertilized with contaminated compost. As a consumer, you get into direct contact with many products that include PFAS. Among them are waterproofing agents, cosmetics, packaging for fast food and paper cups, outdoor gear, and many others. Contact with these products increases the background levels we all have in our bodies.

But as a consumer, do I really have to worry about PFAS?
No, the day-to-day contact with such products is not dangerous. But the problem is that the level of contamination with PFAS is increasing, and high exposure is linked to the diseases I mentioned. It is highly advisable to inform yourself and choose products without PFAS whenever possible. With outdoor gear, for example, there are already such product lines available.

You’re an expert in the distribution dynamics of long-lasting chemicals. How long does it take for PFAS to decompose?
This is exactly the problem. We’re used to thinking that after a certain while, nature will get rid of whatever we put out there. But nature won’t help us with this problem. I’ve spent almost three decades working on this topic. There are many persistent chemicals and some of them last 10 years in nature, others even 20 or 30 years. But to break PFAS up chemically, you have to burn them or expose them to hard ultraviolet radiation. They never degrade naturally. PFAS belong to the most persistent chemicals that exist. This is highly alarming because their concentration is rising.

This is one of the reasons you and other scientists published the “Zurich Statement on Future Action on PFAS” in 2018. In the statement, you urge a distinction between essential and non-essential uses of PFAS. Why?
The main benefit is to have a list of applications for which PFAS is not really necessary. Based on this, the PFAS problem can be solved more efficiently because we have a better idea of where to start with the phase-out of PFAS.

What kind of feedback did you get from the industry?
We wanted to have a process that has a broad backing, hence officials from different countries were involved in drafting the statement. The authorities have shown their will to tackle this problem. And, yes, we’ve even got some constructive feedback from the industry.

Some chemicals that belong to the group of PFAS, namely PFOA and PFOS, have already been banned by law. However, often the industry simply replaced them by other, similar PFAS chemicals. And science doesn’t know their long-term effects. What do you think of this tactic?
This is what we call “regrettable substitution.” It’s counterproductive because it just shifts the problem, costs society a lot of time, money and research effort, and above all, it prolongs the burden of toxic chemicals on the population.

Given this starting position, how do you think PFAS will be regulated in Europe in the future?
European chemical law is unified, so there won’t be differences among the countries. What has been regulated already, namely, the ban of the chemicals PFOS and PFOA, is just the tip of the iceberg, others will follow. Some member states already proposed tighter regulation. The governments have realized that the problem is escalating.

Why is it that one seldom reads about PFAS in Europe?
Maybe because the problem isn’t obvious, takes some time to understand and you can’t see or feel PFAS. A large number of chemicals and applications makes it an unwieldy topic. But in the end, when people are directly affected like in South Baden in Germany, the problem isn’t vague or complicated anymore, it becomes very tangible and urgent. And it should be discussed by non-professionals, because it’s not just a technical problem but has an important political dimension as well.

A naive question perhaps, but if the problem is urgent, why hasn’t anybody presented an efficient way to get PFAS out of the water yet?
First of all, extracting something out of a solution is always difficult, no matter what it is. But more important are the characteristics that make PFAS useful as a waterproofing agent in the first place. Water bounces off them because PFAS don’t like to bind physically with other substances. You need to find something that PFAS can adsorb to, where molecular interactions are possible. There are good reasons that pertain to physical chemistry why this problem is difficult to solve.

How urgent is the PFAS problem from a scientific perspective?
PFAS has already been found in the Arctic and Antarctic. The concentration of these chemicals in nature will rise as long as we don’t do something. This means that the urgency is high, even if it isn’t an immediate threat today. When it comes to PFAS, time is working against us.