Human Transcribed
Dr. Gabriel Sigmund:
I would argue if it cannot be safe by design, we should find alternatives that are. If we don't find alternatives that are, it should be treated by design. If it's not treatable by design, we should find an alternative that is. There are like four steps down this cascade before we get to the point where we just have to accept that a chemical cannot be dealt with. And if we get to that point, we should really ask ourselves, do we really need that chemical? That specific one? And I would argue more often than not, the answer is probably no.
Chai Nussbaumer:
It's widely understood that PFAS, pesticides, and other persistent chemicals can accumulate in different parts of our ecosystem and be damaging to human health.
Micah Schweizer:
But what if the idea of treatable by design could help us change all of that?
Chai Nussbaumer:
In this episode, we'll explore this new approach and how it could transform the way we design and treat persistent chemicals.
Micah Schweizer:
We'll also explore the current state of analysis and remediation, and look at what the EU has done recently to further regulate this issue.
Chai Nussbaumer:
I'm Chai Nussbaumer.
Micah Schweizer:
And I'm Micah Schweizer. This is Balancing the Future from METTLER TOLEDO.
Chai Nussbaumer:
On this show, we explore the world of science and technology and the solutions transforming our lives.
Dr. Gabriel Sigmund:
My name is Gabriel Sigmund. I'm an associate professor at Wachna University Netherlands in the environmental technology department. I work a lot on contaminant treatment remediation, so water treatment, soil treatment, remove and/or destroy different types of pollutants. The things that I work on the most is how contaminants stick to stuff, we call distortion. And if contaminants break, we call this degradation. And ideally what they break into. And those would then be transformation products or metabolites. So those are kind of the mechanistic things that I'm interested in all kinds of different contexts from very nature-based solutions like riverbank filtration, managed aquifer recharge for drinking water production, all the way to really highly engineered technical systems like your biological activated carbon filters or your nanofiltration membranes.
Chai Nussbaumer:
And can you briefly explain what PFAS are and why they're such a significant concern to society?
Dr. Gabriel Sigmund:
Sure. So PFAS is an umbrella term for a number of compounds that estimates are in the several thousands of different chemical molecules. The acronym PFAS stands for per and polyfluoroalkyl substances. According to the OACD definition that was established in 2021, a PFAS molecule is more or less any molecule that has a CF2 group in the carbon backbone or a CF3 group in the carbon backbone. And let's say the most traditional PFASs have several of those carbons that are fully fluorinated, but there's a whole universe out there. And what is quite unique about those molecules is that this bond between the fluoride and the carbon is really strong. And if you have two or even three fluorines at the carbon, it's really, really, really difficult to get rid of them. So they are super persistent, meaning we don't really know of any natural mechanisms in terms of biodegradation that would break them down.
And they've been used since the '40s, produced and used since the '40s. And because they don't break and because they have some additional features that they basically don't like water, but they also don't like oil, so they're both hydrophobic, but also lipophobic, they can be used in all kinds of fancy technical applications and less technical applications. Everyone knows the no stick pans, but there's a whole universe of applications out there.
Micah Schweizer:
And we're talking like firefighting foams. We're talking consumer products like rain jackets. I mean, it's a wide range of uses.
Dr. Gabriel Sigmund:
Precisely, yeah. And basically, even though some industry players knew quite early that there are health concerns, it has only been over the last, let's say one to two decades that those health concerns came into the public eye, so to say. And what is quite concerning is that in terms of endocrine disruption and also causing some cancers, they can be quite harmful at really, really low concentrations. So when I say low concentrations, I'm talking about nanograms per liter. And just to give you an idea, if we think about the Netherlands, which is the country I live in right now, Netherlands a year uses and consumes about a billion cubic meters of drinking water. So that's really large amount of water. If we would throw four to five kilograms of PFOA, one of the PFASs in this massive amount of water, we would already be above the current threshold for safe drinking water.
And right now those chemicals in chemical industry and production are used at the kilotons per year range, not at the kilogram per year range. Of course, those are not necessarily PFOA. Those are other types of PFAS molecules, but just to give you a feeling for how little it takes to contaminate a large body of valuable resources such as drinking water.
Micah Schweizer:
But this gets then to this concept that you've named treatable by design. Can you explain what treatable by design means?
Dr. Gabriel Sigmund:
Certainly. So there is this concept of green chemistry and safe and sustainable by design chemistry. And the idea of that concept is that moving forward, all chemicals we select and use and design should stick everywhere, degrade immediately and not be toxic. I'm simplifying, exaggerating a bit, but basically that's the idea that they are safe. They will stick, they will not bioaccumulate, they will not move far and they will not be harmful. And that is a great concept and idea for many, many use cases and I fully support that. However, there are a number of use cases where those features are not feasible. Pesticides will always be toxic. That's why we produce pesticides. Industrial applications might need some chemicals that are resistant to heat or that may have some features that intrinsically conflict with the safe by design principles. And up until now, those are just, as we discussed a second ago, well, we need them so there is nothing we can do more or less.
And what I propose is that we need a second line of defense. And that second line of defense would be design criteria for chemicals to ensure that we can easily remove them from water, for example, that we can treat them. So treat them by design means that for those chemicals that for some reason right now cannot be safe and sustainable by design because they're intrinsic features that we need conflict with that principle, for those, we need to really make sure that we can easily remove them from drinking water, from wastewater effluence, from those different matrices. Because if we don't, it's a really expensive, really big headache. So that is a concept that I co-developed with some colleagues quite recently and we published quite recently. But I think it's the attempt to have a pragmatic solution oriented approach to this debate because of course I'm very strongly in favor to phase out harmful chemicals wherever we can and persistent chemicals, but we cannot do it everywhere.
Chai Nussbaumer:
And what would you say are the future implications of a chemical that cannot be made treatable by design? That's the ideal in many circumstances, but what if it just simply can't?
Dr. Gabriel Sigmund:
Yeah. I would argue if it's not safe, if it cannot be safe by design, we should find alternatives that are. If we don't find alternatives that are, it should be treatable by design. If it's not treatable by design, we should find an alternative that is. There are like four steps down this cascade before we get to the point where we just have to accept that a chemical cannot be dealt with. And if we get to that point, we should really ask ourselves, do we really need that chemical, that specific one? And I would argue more often than not, the answer is probably no.
Micah Schweizer:
What's required to make a chemical treatable by design?
Dr. Gabriel Sigmund:
So in the treatable by design concept, we have another hierarchy, another cascade because different types of treatment technologies have different environmental footprints. So arguably the smallest footprint is for biological treatment. A wastewater treatment plant is mainly biological because that is a really efficient way to treat wastewater. So if we can design chemicals that degrade, for example, in a wastewater treatment plant, that's awesome. If that is not possible, then the next step would arguably be to make them very easy to separate. And when I say separation, that includes two different types of technologies. Those are absorption technologies, AKA sticking to stuff, activated carbons, unexchanged resins, those kind of materials, or membrane-based technologies such as nanofiltration. That's basically a filter with a very small mesh size. And there, molecular size is an important factor. Charge of your molecule can be an important factor and hydrophobicity of your molecule.
Those are some of the, let's say, general factors and there are additional ones. If we can separate them well, we can up-concentrate them well. If we can up-concentrate them well, it's much easier to destroy them because any destruction is energy intensive, which means if we are able to separate them well, we have a much smaller volume to then destroy. So that's why I would say the next step is ideally a separation up-concentration step. After that, we can then proceed to destructive technologies. And there, of course, the atomic bomb is incineration. You can more or less burn everything if the temperature is high enough. But there are some things in between like electrochemical oxidation or advanced oxidation processes, ozonation, those kind of approaches.
Micah Schweizer:
And what's it going to take for treatable by design to be considered or acknowledged by global PFAS regulation?
Dr. Gabriel Sigmund:
I think treatable by design is broader. It's not just PFAS centric. I really strongly believe that the overwhelming majority of fluorinated chemicals do not have to be fluorinated. So for most PFAS, there are likely alternatives and we know that they exist. We maybe have to change a bit how we do stuff. Sometimes we might have to accept a slight reduction in performance, but we don't need the super-duper ski wax. We don't need a jacket that we can go scuba diving with. That's maybe not necessary. But of course there are those specific applications that still will remain. And for those, I would argue indeed following the treatable by design principles, we can ensure that those emission hotspots, like a manufacturing site, have a much easier job to control their emissions. Because if it's easier to remove stuff, it's cheaper to remove stuff. And if it's cheaper to remove stuff, it's easier to motivate people to do a good job.
Chai Nussbaumer:
Hey, Micah.
Micah Schweizer:
Hey, Chai.
Chai Nussbaumer:
So Micah, when it comes to PFAS and chemical regulation, the EU is leading the way. Since 2007, its REACH regulation has set a broad rule that companies must prove the safety of any chemicals they use.
Micah Schweizer:
REACH stands for registration, evaluation, authorization, and restriction of chemicals. And we spoke with Dr. Alyssa Cordner and Dr. Kimberly Garrett from the PFAS Project Lab about this in season two, but that was in 2025. Has anything changed since then?
Chai Nussbaumer:
Yes. In 2026, 14,000 more chemicals were added to the high concern lists because they were seen as a significant risk to the environment and human health. The biggest change though was the end of a public and private sector consultation that could set the stage for a potential blanket ban on PFAS. This will likely begin in 2027. Manufacturers will have just 18 months to stop making PFAs and they'll have a longer grace period between five and 12 years to fully phase out the ones considered necessary. It's a major shift.
Micah Schweizer:
It really is. And it will be interesting to see how other regions respond in the future. For now, let's focus on the present and look at some of the ways existing PFAS can be analyzed and cleaned up.
Dr. Gabriel Sigmund:
Let's maybe start with analysis. PFAS is a very heterogeneous group of different types of chemicals, but typically in regulatory contexts, as well as in many other contexts, we look at a subset that has been shown to be quite frequent, quite important, or has other types of reasons why it's on that product list. And those are typically around 20, sometimes 40 to 60-ish compounds, but more often than not, it's more like 20, sometimes even less. And those we typically measure with LCMS/MS, so liquid chromatography mass spectrometry methods, those are so-called target methods. So we know exactly what kind of molecule we're looking for and that's what we measure. Now, as I mentioned earlier, you could have a PFAS substructure in a molecule where the rest of the molecule breaks away and then that substructure remains a PFAS. We call those precursor molecules. And there are approaches to basically measure the totality, including the precursors of a given target compound.
There's an approach called STOP assay where we oxidize away all the other stuff. And then we again go with an LCMS to measure those 20 or how many targets you have. So those are kind of, let's say, in the target university approaches that are the most widely used, I would say. Now, if we move from the analysis question to the remediation question, we really need to distinguish separation technologies from destructive technologies. Because for separation technologies, if we know what the contamination profile is, we can measure more or less how well we are doing our job when we, well, up-concentrate, remove them. For destructive technologies, we really need to go for those more comprehensive analytical tools to make sure that we're not just producing a smaller PFAS that is sticking even less and it's even harder to remove, which is a very common thing to happen, that we do not completely destroy our PFAS, but we destroy parts of it.
And then we're left with, from a technological point of view, even harder challenge because smaller molecules typically are harder to remove than larger molecules. In terms of destructive technologies, there are some that we can be decently confident about. Those are incineration at very high temperatures. So above 1000, 1200 degrees, we can be fairly confident that the PFAS are destroyed if we also treat the flume gas accordingly. And ball milling can also work decently well.
Micah Schweizer:
But what's being incinerated if you've identified something at the molecular level that is incredibly spread around an area? What's actually getting burned? It sounds like you can gather up just the PFAS molecules, I assume.
Dr. Gabriel Sigmund:
I wish. Yes. So if we treat water, we can burn the activated carbon that we use to filter the water with. If we use membranes, you have those concentrate streams. So we call this the permit and the concentrate, right? So some water goes through the membrane, some water gets rejected, which are actually quite large volumes, it's typically like 10% of your overall water. So that is a concentrate stream that then needs post-treatment. And that sometimes is indeed incinerated. So that's actually a lot of energy that you need to destroy then. So you can burn the concentrate, you can burn the whole filter, so to say.
And if we're talking about soil contamination, you of course cannot burn huge masses of soil. That's quite tricky. Ball milling has been shown to be promising. So that's literally what it sounds like. So you throw a bunch of soil into a big mill with balls that grind it up and there's so much energy in those mills that can actually destroy the PFAS. There are more sophisticated, less high energy based methods, but I would argue the way they work and the question whether they work depends very much on the circumstance.
Micah Schweizer:
So one begins to see the motivation for making something that's easier to remediate in the first place.
Dr. Gabriel Sigmund:
Yes. Yes, indeed. I could not agree more. I also think when we discuss PFAS remediation and treatment, it's really important to understand that the costs of those technologies are decently high, which means if we were to spend all of our GDP, all of our money that we possibly can find, we could still not keep up with the volumes that are emitted and produced every year. So the only real solution is to stop producing them. We will remediate them. That's my core business. As a researcher, I mainly work on treatment. So we will have those hotspots to treat. We will have those fluxes that we need to deal with and we will. But that's really energy and cost intensive. The only way as a society that we can move forward is stop emitting those types of molecules.
Chai Nussbaumer:
And is it as cost intensive if it's remediation at the source is being done?
Dr. Gabriel Sigmund:
No, definitely not. That's a very good point. So the more upstream we go, the better. So if we can eliminate the emission at the source zone, it's much more efficient. It's much cheaper. It's much better. It's unfortunately not always possible. For industrial emissions, it's definitely possible and we should definitely push for that, right? Because the difference between removing 99% and 99.99% at that scale, at that source is so much bigger than anything we can do downstream in terms of if we can gain that 1% up there, it's so valuable.
Chai Nussbaumer:
In talking about people and the environment, what would be the benefits to society and the environment if safe by design and treatable design was adopted more widely?
Dr. Gabriel Sigmund:
Obviously, direct implications in terms of human health and ecosystem health. Those are kind of quite obvious. If we produce less toxic chemicals, if we use less toxic chemicals, if we emit less toxic chemicals, then all of us are exposed to less toxic chemicals. That's a win by itself. But on top of that, even if we're being super cynical, it's a massive cost saver because it means we don't have to use super expensive treatment technologies to treat all of our drinking waters or any kind of resources. And we will lower the burden on the healthcare system. We can be really, really pragmatic about this. If we put less toxins out there, we'll probably have less toxins to worry about and we'll have less toxins that we need to take action on.
Chai Nussbaumer:
You've been listening to Balancing the Future from METTLER TOLEDO.
Micah Schweizer:
If you found this episode interesting, why not listen to our interview with Dr. Alyssa Cordner and Dr. Kimberly Garrett from season two?
Chai Nussbaumer:
It's linked in the show notes and the conversation goes into more detail about the danger of PFAS to human and societal health.
Micah Schweizer:
If you're enjoying this show, you can help other new listeners find us by leaving a review. Or if you listen on Spotify, leave a message in the comments section.
Chai Nussbaumer:
Also, if you haven't already, be sure to subscribe wherever you get your podcasts.
