�鶹��madou

• Specific ‘forever chemical’ found at unexpected levels in firefighting foam

• New method to degrade PFAS ‘forever chemicals’ found effective in the lab

• PFAS 'forever chemicals' above drinking water guidelines in global source water

• Trying to solve the 'forever problem' of PFAS pollution

Neil Martin 00:00

Hello, welcome to �鶹��madou Engineering the Future podcast. Today we're discussing what we should and shouldn't be concerned about regarding PFAS, and how engineers plan to deal with the issues caused by these complex groups of synthetic chemicals over the next 30 years.

Denis O’Carroll 00:25

“PFAS is regulated in Australia in drinking water at very, very low concentrations, and very, very few people in Australia would consume water that's above those guidelines.”

Neil Martin 00:39

That's Professor Denis O'Carroll, a civil and environmental engineering expert from �鶹��madou. On Engineering the Future, we speak to academics and industry leaders who are embracing cutting-edge ideas and pushing the boundaries of what is truly possible. Join us as we discover how world-changing action starts with fearless thinking in Engineering the Future of PFAS Forever Chemicals.

Hello, and welcome to Engineering the Future of PFAS Forever Chemicals. My name is Neil Martin, and I'm a journalist and STEM communicator working in the Faculty of Engineering at �鶹��madou.

Joining me today to discuss the potential impacts and dangers of PFAS Forever Chemicals over the next 30 years—and how we might mitigate or even solve them—is Professor Denis O'Carroll. Denis is Deputy Head of School Research in the School of Civil and Environmental Engineering at �鶹��madou and is actively working to develop destructive PFAS treatment technologies. He is also investigating the factors that control the fate of PFAS in the environment, and is an associate editor of the Water Resources Research journal. Welcome Denis.

Denis O’Carroll 02:01

Thank you very much.

Neil Martin 02:03

Also with us is Andrew Mitchell, an environmental engineer with 25 years of experience in regulation, policy, emergency management, pollution incidents, and site contamination. Andrew currently leads the National Environmental team at Ade Consulting Group, while previous roles have included being a regulator of contaminated land, funding the clean-up of derelict sites, developing policy and preventative approaches for contamination, managing high-profile remediation projects, and guiding the Department of Defense in investigating and managing PFAS contamination. Through this work, he has developed significant expertise in negotiation, influencing, community consultation, and risk communication. Hello, Andrew.

Andrew Mitchell 02:51

Hi. Glad to be here.

Neil Martin 02:53

So we're here to talk about PFAS—or to give them their full technical name—per-and-polyfluoroalkyl substances. I think that's about as hard to say as it is for them to be broken down, which, of course, is the big problem, and that's why they're known as "forever chemicals."

Growing media attention about PFAS has started to spark public debate about how dangerous they might be and what we need to do in the future to deal with them. Denis, in the past year to 18 months, people might have started to read a lot of news articles about these chemicals, which have been used in things like non-stick frying pans, food packaging, and firefighting foam for many years. But can you explain in very basic terms to anyone who might not be sure—what are PFAS?

Denis O’Carroll 03:45
Well, they're chemicals. There's over 14,000 of them, specific chemicals that have carbon backbone and then fluorine atoms attached to that and with various head groups or end members type thing. And they're pervasive in the environment, they really like to go to interfaces. So if they're like a soap, that's why we use them in firefighting foams, is they would go to the interface between the oil, the fuel and air, and then they would smother out the fire. They're quite efficient.

Neil Martin 04:16
Andrew, it seems to me, doing my research, that these things are designed to resist pretty much everything. They resist heat, they resist grease.

Andrew Mitchell 04:24
They’re amazing chemicals. So it's part of, you know, looking at contamination in the environment. You're looking at the marvelous chemicals that we've used for decades. And then you go: ‘Oh gee, I guess this one actually has problems’ because some of its features are also some of its bugs, if you like. So if you remember back to your high school chemistry in the periodic table of the elements, the element fluorine is in the top right-hand corner. It is the most electronegative element in existence. And because of that electronegativity, the bond it forms with carbon is really strong, really tight. So much so that, unlike most organic contaminants so far, no one is aware of any microbes, bugs that can gain energy from carving that bond. Most other contaminants, like your dry-cleaning solvents or your petrols, other organic contaminants will break down eventually in the environment through a range of mechanisms, including biological and physical and others. But there's a group of PFAS chemicals, the terminal degradants, I guess is a good name for them, that tend to not break down any further.

Neil Martin 05:39
They’re kind of a bit too good at their job, I guess.

Denis O’Carroll 05:43
Yep, they're well engineered, absolutely.

Neil Martin 05:45
And these things were, I think, developed first in the 1930s but kind of gained traction in the 1950s maybe. And am I right in saying, you know, non-stick frying pans, firefighting foam, food packaging, what else have they been used for?

Denis O’Carroll 06:02
Well, we would have used it stain resistance in carpets, maybe fire resistance in some materials as well. We would have had it in say, Patagonia used to use it all the time for weatherproofing their jackets, and they got out of that market maybe 10 years ago, and they're having difficulty getting the same efficiency of weatherproofing because they don't use PFAS anymore. So it would have been pervasive, maybe in our tents. And ski wax, yeah.

Neil Martin 06:26
I heard that ski wax is a thing. It's quite an unusual one, I think. But I guess, for the same reason that it gives you some good protection on your boards, I guess, and your skis.

Andrew Mitchell 06:36
Well if you think of the properties of a Teflon fry pan or PTFE lubricant for a bicycle, and that, you know, the Gore-tex jackets, the ski wax, the lubricant is very, very good. So yes, it's been banned in some ways, but you can still find it in your local ski shop at the slopes. And by the very fact that you must re wax your skis on a regular basis, you can guess where the wax is ending up: all over the mountains. But even just looking around this room, my coffee cup at the moment is it's got a PFAS coating on it. Your takeaway lunch, the box of chips would have had a PFAS waterproof coating. Some of those coatings on food packaging up to 50 parts per million of PFAS, which, when we're talking scale, is, is quite a high concentration of PFAS in everyday items that people are using and are not necessarily aware of what they contain. So, scale is really important. When considering the PFAS guidelines and PFAS in the environment. Those of us who practice in the field talk about parts per million, parts per billion, parts per trillion. So, one part per million is one milligram per kilogram. A part per trillion is one nanogram per kilogram, or one nanogram per liter, if you're looking at water. The numbers that we're talking about are, you know, some people like to use Olympic swimming pools. Well, that metaphor runs out with PFAS, because it's Olympic swimming pools lined up between Melbourne and Sydney, and just put one drop in that, and that's one nanogram per liter. It's very, very, very small.

Neil Martin 08:09
And I think you covered it a little bit before Andrew. But in general, why are these things so hard to break down? I guess engineers and scientists have tried now they've identified this problem. It's just that the bond between those atoms is so strong, is that right?

Andrew Mitchell 08:26
Yes. So to destroy PFAS, rather than separating it from the environment, you need to get the temperature up quite high, maybe 1000 degrees or so. But the US Department of Defense and Department of Energy and EPA have been funding marvelous research projects known as, I'll just use the acronyms SERDP and ESTCP, quite long names, but if you look up S-E-R-D-P and E-S-T-C-P, you'll find them online. They've funded some magnificent research into a variety of destruction methods that use ultrasonication. They use a reversal of the methods that we use to generate the PFAS, so electronic or electrical methods, and they've had some very good success, but it's difficult.

Denis O’Carroll 09:12
And costly. So yeah, it's at scale, very costly—and that's the US government. The Australian government has also funded, I think Andrew was alluding to that as well. And I guess, with regards to how hard they are to degrade. In a fire, if you're using a firefighting foam, you do not want it to degrade. So it's engineered such that it will not degrade under, let's say, normal fire conditions. So really, it's designed so that it does resist environmental degradation.

Neil Martin 09:40
And this is why they've picked up this name, forever chemicals, and also that they've been found kind of everywhere, really. That's right. I've read stories that they're in 99% of the population. Is that correct? Do you think?

Denis O’Carroll 09:54
Yeah, absolutely. Andrew gives guest lectures in my class, and he shows a nice graph, and it is decreasing with time. Certainly the ones that are regulated that we're paying attention to are decreasing with time, as major international suppliers or manufacturers are phasing that product out.

Andrew Mitchell 10:11
Can I pick up on something? So the notion of forever chemical, it's kind of neat and sexy, but lead contamination has been around since the Romans. Lead is a forever chemical. It's elemental. You can destroy PFAS, but you can't destroy lead unless you put it into the heart of the sun. Mercury, arsenic—these are also forever chemicals that cause real harm to human health, where the effects are very well demonstrated. The dose response relationship is very, very clear, and people around the world—often of lower socioeconomic groups—are being harmed and children are being poisoned from exposure to these elements.

Neil Martin 10:49
Picking up on that, though, people are starting to read stories in the newspaper about the potential health problems of PFAS. I believe it's been designated as a carcinogen in at least America, if not by any kind of global body. Maybe you can correct me.

Denis O’Carroll 11:08
By the World Health Organization has.

Neil Martin 11:10
So globally has, and I guess people are maybe starting to get scared, if they put those two things together—it's in 99% of people, and it's also a carcinogen. They're kind of worried about health aspects. Do you think that's fair?

Denis O’Carroll 11:23
Well, bacon and alcohol are also carcinogens, and we don't really worry about them. So I think we need to have a measured response and obviously pay attention and reduce, to the extent possible, PFAS in our daily lives. For sure.

Andrew Mitchell 11:40
Contextualisation is important. So what is different about PFAS? Yeah, let's compare it to, say, lead poisoning the Romans had. It's not naturally occurring, right? So it was made in a factory. It has traveled a long, long way from where it was released in the environment, and the people who are exposed to it often have no control over that exposure. I choose to drink red wine, have a steak, eat bacon, and wear my Gore-tex jacket when I hike. I choose that. I choose that exposure. But no one is choosing to be exposed to PFAS contamination—either directly through their drinking water or indirectly through living in the modern society that we are.

Neil Martin 12:20
Do you accept that some people might be scared, though, like when they read those stories, and there might be certain specific media publications that like to, you know, get clicks and maybe scarembviously grew over time. Do you think people might start thinking that that would be the case with PFAS?

Denis O’Carroll 12:52

Well, absolutely. People are scared. PFAS is regulated in Australia in drinking water at very, very low concentrations. That’s somewhat debated in the literature—should it be that low? It’s regulated similarly to other jurisdictions, but some countries have lower limits. Very few people in Australia would consume water above those guidelines. So if someone reads in the media that all of Sydney's water is contaminated—that would be false. That’s scare mongering. In the Blue Mountains, about 50,000 people have consumed water above US and EU guidelines, and also the incoming Australian standards. It gets tricky because the guidelines are becoming more stringent over time.

Neil Martin 13:56

I believe the Australian regulations have been under review recently. They’ve announced plans to lower the limits—is that correct?

Andrew Mitchell 14:09

Well, it's out for consultation. The NHMRC is responsible for drinking water guidelines in Australia. A consultant they hired recommended no change, but NHMRC members elected to revise the guidelines against that advice—and explained why in their published document. As a practitioner, this introduces complications. Another agency, FSANZ, sets food exposure limits using the tolerable daily intake concept. For PFOS, FSANZ says 20 nanograms per kilogram of body weight per day. Multiply that by a 70 kg adult drinking 2 liters daily, divide by 10 to account for other exposure sources, and you get the current guideline of 70 ng/L. The proposed guideline is 4 ng/L—that’s 15–20 times lower. FSANZ stands by 70, NHMRC is proposing 4. The problem is: soil standards for growing veggies depend on TDI. Do we use FSANZ or NHMRC? FSANZ sets the milk guideline, but NHMRC might define recycled water and biosolids. It creates regulatory disconnect.

Neil Martin 16:16

Would you prefer the numbers to be the same? And do you think with more research, they’ll eventually align?

Denis O’Carroll 16:31

Yes, they should be the same. Australia should have one standard for daily intake. If, say, 10–20% comes from water, you calculate that number. Then there’s food, biosolids, soil—every guideline measures how much your body uptakes. First, we must agree on one acceptable value, then break it down across exposure routes.

Andrew Mitchell 17:10

Let’s take a step back. PFAS fits into two domains. One is contaminated sites—places with large PFAS releases, often from firefighting. Defense departments, industrial sites, etc. These are point sources from past activities. The other domain is incidental or ambient exposure—recycled water, drinking water, biosolids from sewage treatment, compost. That coffee cup you toss into compost leaches PFAS into the soil, into veggies. Changing guidelines blur the line between contaminated and background exposure—everything ends up above guideline.

Neil Martin 18:33

Earlier you mentioned tolerable levels. How are they determined? And what should they be?

Denis O’Carroll 18:42

I’m not a health professional, but different governments use rats, mice, etc., to study health outcomes and apply scaling factors. It gets complicated.

Andrew Mitchell 19:04

Without offending toxicologists, here's a simple version: researchers feed large chemical doses to small animals for a short time, observe effects, and extrapolate to humans long term. It’s hard. So guidelines build in uncertainty factors. Poison the rat, get a dose, then divide by 10 for various safety margins. The final tolerable daily intake might be 300 times lower than the experimental result—hopefully protective.

Denis O’Carroll 20:06

Another method involves studying isolated populations, like an island where people eat a lot of fish. You can link intake to outcomes—though they’re exposed to more than just PFAS. That makes it hard to say if it’s one chemical or a mix.

Andrew Mitchell 20:40 Causation vs. correlation is incredibly tricky. Epidemiologists from the Australian National University told the Senate inquiry last year that PFAS-affected communities are experiencing stress and anxiety. That’s real. But they couldn't confirm other health effects. The uncertainty is high.

Denis O’Carroll 21:32

And that stress affects lives. �鶹��madous lose value—that’s a real burden. If health declines, is it from PFAS or from stress? That’s the challenge.

Neil Martin 21:53

Everything’s interwoven.

Denis O’Carroll 21:55

Yeah.

Neil Martin 22:05

Looking ahead, what technologies are being developed to detect or remove PFAS?

Andrew Mitchell 22:09

Detection is challenging—but PFAS can be tracked at very low concentrations due to their chemical makeup.

Neil Martin 22:25

Is that because they don’t go away?

Andrew Mitchell 22:27

No, it's because they pop up on the machine very clearly. They are really easy to detect at crazy low concentrations. 10, 100,000 times lower than you can detect other contaminants.

Neil Martin 22:38

So we don't have a problem with detecting them?

Denis O’Carroll 22:39

It is time consuming. I was just in the field in the Great Barrier Reef looking at contaminants, and it would take, you know, to get one water sample, it might take three days of pretty hard work to get a batch of them through and tell you the concentration. So it is straightforward to do with some nice instruments.

Andrew Mitchell 22:54

Yeah and it's commercially available, so you can go to a commercial lab and pay, I don't know, $150 and get your result back in a week, or pay double that and get it back the next day.

Neil Martin 23:04

So the bigger focus is on new technologies to degrade. Would that be correct?

Denis O’Carroll 23:10

Well, an instrument to detect PFAS might cost half a million dollars. So if we could do it easier, then certainly people are actively looking at quantification at low concentrations as well, because it is a bit of an expensive exercise. You know, Andrew's saying $100–$150 per sample. But if you go to a contaminated site that—you know—you’re doing hundreds of samples, that adds up pretty fast.

Neil Martin 23:32

When I was doing some research for this episode, and I was looking at potential new technologies that might be out there in terms of removing PFAS, I saw a few different bands of ideas. Better filtration was one, bioremediation, chemical destruction. Could you maybe talk about those potential improvements in technologies?

Denis O’Carroll 23:55

Sure. Well filtration, an ion exchange resin or activated carbon would be traditional ways that you would remove PFAS, and in the Blue Mountains, they would be using something like that. And you know, we would in our lab, actively be looking at ion exchange, looking at a resin that you can engineer to remove certain types of PFAS and really optimise it. Is really the name of the game, because a problem, not necessarily in Australia yet, but certainly internationally, is the shorter chain PFAS are hard to remove and hard to remove using activated carbon. So they're looking at what other technologies, how can we maybe optimise it such that we can remove them well and remove all PFAS.

Andrew Mitchell 24:37

It's pretty common for a treatment train to be designed, so it's very easy to remove PFAS from clean water. It's quite hard to remove it from dirty water. First you need to make the water clean. So it depends whether you're treating surface water or groundwater or landfill leachate. You need to first remove pretty much nearly everything else, except for salt, and then you can remove the PFAS as well. So activated carbon, ion exchange, reverse osmosis—it works, but ion exchange is better. A neat technology is foam fractionation. So if you blow bubbles through the water, the PFAS will stick to the edge of the bubbles. They like interfaces, as Denis said. They love the air–water interface, so you blow bubbles through the water, and it makes a foam. The PFAS is in the foam, you separate that out, and the water comes out clean. It's a really cool technology, and it works better if the water is dirty.

Neil Martin 25:35

And then what do you do with that? What do you do?

Denis O’Carroll 25:36
At high concentration, and you need to do something with it. But you're not treating a large volume, you're treating a relatively small volume.

Neil Martin 25:42

But that hasn't gone away. You've just concentrated it.

Andrew Mitchell 25:45

So, if you would take your activated carbon to the landfill, there's not much else to do with it. In the US, they recycle or re-regenerate their activated carbon and put it back into the community. Ion exchange resin—there's single-use resin, and there's regenerable resin, where you use methanol to take out the PFAS, and then you can reuse the resin. Foam fractionation—you get a hyper-concentrated fomite, which you can then entrain on an activated carbon or resin if you want, or just take the liquid and incinerate it. There are some cement kilns that are licensed to take concentrated PFAS, like your firefighting foams. In Melbourne, there are some waste facilities that are licensed to incinerate PFAS and soils.

Neil Martin 26:34

I guess with all of these things, there's a cost involved—time, money. Is there a point at which you say it's not worthwhile to carry on? Going back to those tolerable levels, I guess you can't get rid of this completely?

Andrew Mitchell 26:51 Well it's not just the human health effects—there’s the ecological effects as well. And the current ecological guideline number for PFOS is 20 times lower than the new proposed drinking water guideline. It's 0.2 nanograms per litre, and that's pretty much the detection limit of most commercial labs. So if you are going to do a treatment process, you need to work out: What are your measures of success? How clean does it really need to be? If it's a separation process, then you need to work out what is the economical way to destroy the PFAS that you pull out. In some cases it's taken to landfill, but in some cases, it's incinerated.

Denis O’Carroll 27:31

Something to bear in mind is the carbon footprint associated with all these treatment technologies. We talked a little bit about soil earlier, and a problem is that soil—it could be just a little bit over in a lot of places. And then the question is: What do we do with that soil? You can't move your soil from here to there. Are we going to incinerate all these soils? Are we going to wash them? How are we going to do it? We have to come up with some kind of pragmatic, risk-based approach and understand there's going to be ambient levels—and find out what's an acceptable level. Because we don't want to cause climate change by removing PFAS. That's not the outcome we want.

Neil Martin 28:08

Might be a tricky question, but where do you see this issue in 30 years’ time? Do you think somehow it will be solved, or do you think this will still be an ongoing conversation or debate?

Denis O’Carroll 28:20 Well, that's a great question. Let's say five years ago, people thought it would go away—and it's only become more stringent, with heightened awareness associated with it. So the crystal ball—we're probably not great at it. Really, what we need is some health advice.

Andrew Mitchell 28:35

I think in 30 years’ time, it'll be passé. We'll have other issues, I'm sure. I've been working in this field now for nearly 30 years, and we keep talking about doing ourselves out of a job. We say, "The great big, dirty, nasty contaminated sites—yep, they're cleaned up." But we keep finding new and interesting things. Currently, PFAS is new and interesting. It's interesting scientifically and chemically—it’s just a bit weird, a bit different, and it is legitimately very interesting. We keep getting surprised when we look into it more and more, and we keep learning. But I would advocate that in 30 years' time, the health guidelines should be resolved. We should have a fairly solid understanding of what is safe and what is not. And we may be living in a world where everyone is always exposed to PFAS levels above the safe limit. That is a possibility—and we’ll just have to live in that world, because we don’t have another one. Or it may be that the limits go up, and attention is focused on cleaning specific problems, banning specific chemicals, changing specific behaviours—and then everything else is okay.

Neil Martin 29:50

Another thing about looking to the future: these chemicals were introduced in the 1930s and increased in the 1950s. As we said before, they were very good at what they did. So we need to find a replacement. People still need to fight fires; non-stick pans are still quite useful. How easy is it going to be to have those items made with something new?

Denis O’Carroll 30:18 Well, we need to go and look at where PFAS is used, and then find alternatives for that—or make it unavailable with notice. The Australian Government is limiting the amount of some regulated PFAS that comes into the country—that goes into effect in a couple of months. So effectively, the industry will have to come up with something else. We'll have to use something else for those few uses. As that expands, the European Union wants to ban it, with some conditions. So when that happens, people will be looking at different types of chemicals.

Andrew Mitchell 30:53 There are some challenges ahead. The fact is that PFAS chemicals are just really, really good at what they were designed to do. So replacement chemicals aren't always as good, and replacement approaches aren't always as good the fluorinated foams. As Patagonia is finding, it's hard to make your jacket as waterproof as when you use Gore-Tex. Scotchgard was a great waterproof treatment for carpets and soft upholsteries—it was full of PFOs, so now we have some more stains on our carpet. Your takeaway food may get through the container faster, or maybe we should just do away with disposable food containers. Just bring a ceramic. I bring a keep cup to the cafe usually. So it's not just changing chemicals, it's also changing behaviours and expectations.

Neil Martin 32:06

I don't know if this is playing devil's advocate, but if you start designing new chemicals, is there a potential that in 20 or 30 years, there'll be a new podcast saying, what about all those new chemicals that are causing problems?

Andrew Mitchell 32:20

Oh, there's always perverse outcomes. Some people were scared of drinking tap water in Sydney as a result of the Blue Mountains issue—and that's outrageous, because Sydney tap water is amongst the cleanest in the world. It's really, really good. Some people may be turning to bottled water, which introduces risks of microplastics. Now, microplastics—that's another podcast. Nanoplastics too. It’s a question mark whether they’re a concern. We have a body burden of PFAS. We also have a body burden of plastic—in our brains and other parts of our bodies where you'd think they shouldn't be. What are they doing? No one knows. So any change in behaviour brings risks of perverse outcomes.

Neil Martin 32:59

And the new chemicals as well—I guess you're not going to know until a period of time moving forward.

Denis O’Carroll 33:06

When you design or seek approval for them, you do sort of know the structure, and you can come up with some thoughts around that, certainly. But you wouldn't know fully. Maybe they wouldn't do 100% due diligence in advance.

Neil Martin 33:19

Do you think the regulatory environment is better now? Are people looking forward and asking: Are they going to degrade? Will they cause problems down the track—things that maybe weren’t considered in the 1930s or 1950s?

Denis O’Carroll 33:34

There’d be a bit more awareness, but I doubt there's as much awareness as we might want—certainly.

Andrew Mitchell 33:41

I think we’ll keep getting it wrong, to be honest. Those firefighting foams caused many problems. The manufacturers told users they were biodegradable. Technically they were—80% broke down within a certain timeframe. It’s the remaining 20% that was—and still is—the problem. The chemical industry is clever, motivated, better resourced than government. Government bans one chemical, and the industry swaps out a fluorine for a chlorine, or a bromine, and calls it something else. Then government takes 10–20 years to catch up.

Yes, some PFAS have been banned in Australia as of 1 July. But most of those were voluntarily withdrawn 25 years ago. You can see that in blood testing—the PFOS levels plummeted once 3M voluntarily removed it from products in the late 1990s and early 2000s.

Neil Martin 34:51

Do you have some sympathy, though, especially in terms of firefighting foam? It was designed with good intentions. These people were trying to do good, and now it's being—maybe demonised is the word. There's a moral question there.

Andrew Mitchell 35:15

Oh, it’s a massive moral question. These are the good guys—Department of Defence, fire brigades—organisations putting their lives on the line for others. They followed manufacturers’ instructions, trained properly, did everything by the book. It's horrendous that they're being painted as villains now. There’s definitely culpability from manufacturers for lack of transparency and poor communication. Thirty years into the future, we need better information and transparency. If a manufacturer discovers a potential risk, don't wait 30 or 40 years for it to surface in court.

Denis O’Carroll 36:13

Two things: First, firefighters used the foam, so they have the highest blood levels—they deserve support. Second, governments must step up. If they have information that's concerning now—or will be later—they need to inform the public. Message it well. Just because PFAS wasn’t regulated in Australia doesn’t mean the public shouldn’t have known. It was regulated in the US and Europe. Failing to inform creates confusion and anger—and rightly so.

Neil Martin 36:59

And just to touch on something you mentioned—are there firefighting foams now that don’t rely on PFAS?

Denis O’Carroll 37:12

That’s right. Fluorine-free firefighting foam exists and has been used in Australia for some time. It’s now the standard—not PFAS-laden foam.

Andrew Mitchell 37:21

Nearly everyone has now changed. After issues with PFOS—the “O” stands for octane, eight carbons—new C6 foams were used from the early 2000s to about 10 years ago. These are now being phased out in favour of fluorine-free foams. I don’t have special knowledge, but I’m quite sure Defence, airports, fire brigades, and petroleum terminals are all using fluorine-free foams now.

Denis O’Carroll 38:03

Major organisations don’t want a legacy. If they can put out fires safely, they’ll choose the alternative. There were some specific needs—like submarines—that took longer, but I believe they found solutions.

Neil Martin 38:19

Final question: If you could give one piece of advice about PFAS to individuals, businesses, or governments for the next few years, what would it be?

Andrew Mitchell 38:35

Don’t sweat the small stuff. Context: We’re all exposed to PFAS—everywhere, all the time. You say 99%; I say 100% of people worldwide have PFAS. It's even been detected in rain. So we need to find the big problems, fix the big problems, and not stress the small stuff.

Neil Martin 39:01

And how would you define the big problem? What are your one or two?

Andrew Mitchell 39:06

Two dimensions: One is contaminated land—sites that clearly need intervention. The second is chemical use—people are being exposed to PFAS in daily life without even knowing it. That’s a little crazy and needs to stop.

PFAS is in makeup, eyedrops. Miebo, for instance, is 100% perfluorohexyl-octane. When you use it, the octane drops off and PFAS enters your bloodstream and eventually sewage treatment. That needs labelling and regulation. Food packaging too—it needs to be PFAS-free to safely compost it.

Address contaminated sites and cut off the major flows of PFAS into our environment—everything else will be manageable.

Neil Martin 40:20

Denis, how easy will it be for you to give one piece of advice?

Denis O’Carroll 40:23

Well, I'll try to be shorter, but Andrew had some great thoughts. I think the public needs to know that medical advice suggests PFAS—maybe only 20% comes from drinking water. So if you're concerned about PFAS in your daily life, you need to look at all sources of use. I would say, by and large, Australian tap water is great.

Andrew talked about contaminated sites, and kind of alluded to our day-to-day lives. At wastewater treatment plants and utilities—when we flush a toilet, we’re putting PFAS down the drain. That goes to the treatment plant. And like the firefighters, we shouldn’t brand utilities as the bad guys—it’s us. We need to consider the chemicals we use, especially PFAS and others we flush, because they don’t degrade. They go out in treated water or into biosolids. So it just stays there and ends up back in the environment. We need to stop using it so it doesn’t get there in the first place.

Neil Martin 41:21

That's great advice from both of you. It's been really interesting to speak with you about this important topic. Professor Denis O'Carroll, many thanks for joining us.

Denis O’Carroll 41:32

Thank you. Appreciate it.

Neil Martin 41:34

And also to Andrew Mitchell, it's been a pleasure to chat.

Andrew Mitchell 41:37

Likewise.

Neil Martin 41:39

Unfortunately, that's all we've got time for. Thank you for listening. I've been Neil Martin, and I hope you'll join me again soon for the next episode in our Engineering the Future series.

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