How should society manage the use of chemicals? A conversation with Todd Gouin
In this episode I am joined by Todd Gouin of TG Environmental Research. Todd and I have a far-reaching discussion about the science and policy of chemicals in the environment.
Our conversation covers:
Todd's career journey and the role of Don Mackay
The concept of environmental persistence
Tools for chemicals management and the evolving policy landscape
Exposure assessment and risk assessment - the importance of considering exposure in addressing chemical risks
How sustainability is changing the way we look at chemicals
How science is produced, and communicated in the media
How well do our tools fit what is happening in the environment?
Biodiversity and the roles of chemical and non-chemical stressors
Changes to policy around persistence - storing up problems for the future?
Why biodegradability is important for consumer-facing sectors
Persistence in the discussion on product circularity and innovation
What's at stake? Balancing costs to society
The need for multidisciplinary expertise and the role of industry
Recorded on 12th March 2025
Environmental Fate and Exposure - TG Environmental Research
A review of DEB theory in assessing toxic effects of mixtures - ScienceDirect
Why environmental persistence should be a top priority for safe and sustainable products
Prefer to read? Here is a transcript:
Chris: Hello everyone and welcome to the Chemical Journeys Podcast. My name is Chris Hughes, and I'm joined today by Todd Gouin, who is an independent scientist. Todd, thanks for joining me.
Todd: Very happy to be here.
Chris: I'm really happy to have you on. You and I have known each other for quite a few years now, and you're very well recognised within your field as an expert in exposure assessment, risk assessment, and also more recently the issue of microplastics. You and I have come across each other quite a bit at various conferences and other events. So you were one of the first people I thought to invite onto the podcast, and I'm really pleased that you're here. And we're trying something new, because we're face to face in a podcast studio in Chester. So, welcome.
Todd: Yeah, fantastic to have a chance to come to Chester. I think the last time I was here I ran the Chester Marathon, and it was the first time I touched three hours — so it was a great time then, and it's great to be back here again, and to have this opportunity to talk a little bit more about what we do on a day-to-day basis.
Chris: Yeah, exactly. I'm glad Chester holds a special place in your heart. So, let's start, Todd. This is kind of like a biographical podcast where we try to weave in the topic of chemicals in the environment, and all the complexity of that — from the natural science and the social science, to politics, psychology, and the economy. I like my guests to talk about their backgrounds, their motivations, and their career journey. So why don't we start there?
Todd: Yeah, for me it starts at a fairly young age of about 14, when I became interested in the environment, but at the same time I wasn't very academic. So I wasn't doing very well at school. I come from Canada, and they have a tiered system when you get into high school. I was recommended to go to a lower tier of high school, which effectively meant I wouldn't be able to go to university. I kind of just drifted through high school and then ended up going to a technical college.
I started off in the area of civil engineering — I was interested in that sort of aspect of things — working towards a civil engineering technologist diploma. Effectively I was doing land surveys, working in the survey area. Which was kind of fun, because one of the aspects of doing surveys on land is that you have to balance out your contours and do circuits so you come back to where you started — so everything has to balance out mathematically.
At the same time I was interested in the environment, in particular the chemistry side of things. I had an interest in chemistry, so I started to shift a little bit away from civil engineering towards what is known as environmental engineering, getting an environmental engineering technologist diploma, which put me on the track of working in wastewater treatment facilities and monitoring the performance of those systems, for instance.
However, as part of that programme, I ended up doing a co-op term at Environment Canada, where I found myself preparing air samples for the Great Lakes area. There's a monitoring network in the Great Lakes known as the International Atmospheric Deposition Network, and as part of that network the goal was to monitor the concentrations of various organic contaminants in the atmosphere throughout the Great Lakes — including polychlorinated biphenyls, or PCBs, and various organochlorine pesticides.
So my job was just loading and unloading the air samplers going out to the different sites, but also looking after the site I was based at. I did that for a number of months, and the fellow I was working with — Ray Hoff was his name — was very inspirational in terms of what he was doing. This was in the early 90s, working on organic pollutants in the Great Lakes, and I really enjoyed my time at Environment Canada, the chemistry side, the organic pollutants, and trying to understand the source-receptor relationships of how these chemicals move in the atmosphere.
We were located at a rural site, and effectively you could detect, for instance, atmospheric events that would move out of Toronto — which was south of us — and you would see a distinct signature in terms of pollutants coming in from Toronto. So it was a very nice beginning, thinking about the causal relationship between a chemical exposure in the air and how different events in the environment help influence what's going on.
After I finished working there, I struggled to find full-time employment and was working midnights in a convenience store for quite some time before I started working in a plating industry, doing some wastewater treatment for metal waste coming through plating operations. I managed to save enough money and realised I could probably do all right at university — so I went back as a mature student.
At which point I found myself floating a little bit, not sure whether I was more interested in the chemistry side, and I also took a lot of humanities courses. One thing I found really interesting on the humanities side was that there were a lot of opportunities for debate — to reflect on what you were reading, to consider the arguments being presented, and to be critical about different perspectives. You begin to appreciate that no matter what you read, everyone has their own personal interpretation, and it's not necessary to say one person is correct and another isn't — it's about how you articulate your thoughts.
Whereas on the science side, it was very systematic and prescribed. You had PV = nRT, you ran the equation, you did the lab, and you worked towards a specific outcome — not much room for flexibility or questioning. That is, until you discover that the ideal gas law describes an ideal system, and there's another equation that describes non-ideal systems. And that's when you begin to appreciate that even the chemistry, the science, is open to debate.
During the senior years of my undergrad at Trent University, I was taking a course on geochemistry, and I showed up late to one particular class — I think the only reason I went was perhaps to hand in a homework assignment. There happened to be a guest lecturer that day, who turned out to be Don Mackay. He was giving a guest lecture as part of that course. And I turned up just in time for him to pass around a piece of paper looking for a summer student, with a number of questions he was pursuing. One of the questions that caught my eye was: what is persistence? Of course, he was talking about organic chemicals in the environment, and I'd done my work at Environment Canada several years before — so I thought it was a very interesting question and I went and talked to him.
Apparently I was the only student who went and talked to him, and he kind of looked me up and down and said, well, it beats working at McDonald's over the summer. So he gave me the job, to work within his group, to tackle this question of what is persistence. This led to my first publication, considering overall environmental persistence and trying to map that out into chemical space — and I did that as part of my undergrad.
What was really rewarding within that group was the opportunity to work with Don Mackay. Once you get to know him, you begin to appreciate where he came from and what he represents to the field of environmental chemistry, environmental fate, and exposure modelling. Within the group we had Ian Cousins, for instance, who was doing his postdoc, and Matt McLeod, who was doing his PhD work at the time, along with others who joined later, including Chris Warren. So we had, I think, a very dynamic group with a lot of opportunity to exchange ideas and challenge each other.
So these are different questions that we face today that keep coming up. That was in 1999, when I was working on this question of what is persistence. And I find it quite fascinating that we seem to continue to be addressing this issue. I know that you're heavily involved in that, and I think it remains an open question. You've been talking a lot about it in your podcast, which I've been listening to over the last couple of months, and this theme of persistence definitely comes up time and time again.
There's a regulatory component — a definition of how we define persistence — but I'm still perhaps struggling a little bit from a scientific perspective as to what that means. I think it's more of a philosophical question. We have regulatory definitions around a specific half-life — a media-specific half-life that defines a chemical as being persistent — and I'm still perhaps trying to understand what that means and how it helps to protect people and the environment. Because it's just a number that somebody has derived and put into a regulatory space. Is it really meaningful?
And then we have other terms which are more loosely described, such as 'sufficiently persistent' — which came from a publication with Ian Cousins and others — and then I guess Martin Scheringer most recently advocating for 'extreme persistence', if I recall correctly.
And Don had a paper published quite some time ago where he talked about persistence, long-range transport, bioaccumulation, and toxicity as being what he referred to as quasi-intrinsic properties of chemicals — effectively supporting the idea that persistence and bioaccumulation are intrinsic properties that we can identify and try to prevent from being used in certain contexts. So can we come up with a way of thinking about these properties, identify chemicals that are used in the market, and try to address those chemicals? So I think that's where the hazard scheme kind of falls into play.
But I also — as I've learned more about aspects of biodegradation and bioaccumulation — I've started to see that there are a lot of system-dependent components that exist within those properties, and that has led me to challenge a little bit the idea that they are intrinsic properties. They seem to be system-dependent properties.
I think as we've advanced over the last 20 years in particular, we've seen a lot of improvements in the way we can do exposure assessment, and it seems it would be beneficial if we could try to strengthen the use of those additional tools as opposed to perhaps relying too heavily on hazard criteria such as persistence and bioaccumulation. If the end goal is to protect the environment, why not apply the science we have today to try to quantify what the risk is, and put greater emphasis on risk as opposed to hazard?
Chris: Yes, I fully agree with what you're saying about the importance of exposure in determining whether chemicals are going to cause harm in the end. And I understand that these frameworks that were historically developed to identify the problematic chemicals — the PBTs and the POPs — were important tools for identifying these chemicals. But depending on where these frameworks are implemented, there is a risk or exposure element envisaged. So, for example, under the Stockholm Convention, a risk profile is intended to be included in the determination of decision making.
And I wonder — at some point it was decided not to include those considerations in European Union frameworks like REACH, where the simple hazard properties would be determining whether or not a chemical could remain on the market. But we are where we are with respect to those decisions. And there is a debate raging now amongst scientists working in this field. It also has a geopolitical dimension, because there's almost like a North American position and a European position.
But I think another issue that relates to this is how wide is the net that catches the chemicals determined to be problematic. With the Stockholm Convention, for example, half-life cut-offs of 60 days are applied to water, or 180 days in soil and sediments. But when REACH was introduced, they introduced persistent and very persistent criteria where the P criterion was 40 days and 120 days, as opposed to 60 and 180 — and that was one example of where an additional layer of conservatism was introduced in the assessment. But we see more and more of these kinds of layers of conservatism being introduced.
And then, of course, we see new concepts emerging — as you alluded — like the PMT and vPvM concept, which is actually targeting a completely different area of chemical space that now comes into scrutiny. And if you read the European Chemicals Strategy for Sustainability, the direction of travel was that those chemicals would also be considered substances of very high concern under REACH — they would also be eliminated on a hazard-based perspective.
I've been thinking a lot about that particular concept, and maybe we can get into that. But I have concerns about the long-term direction of travel of these policies and how many chemicals may ultimately be caught by them in the long run. And to go back to what you were saying — I think one of the unfortunate situations is that we're not considering exposure. We're not discriminating between those chemicals that are used in high tonnage or high exposure. And we potentially risk a lot of harm to the chemicals that we use and benefit us in modern life — reducing our standard of living — with this goal of protecting health and the environment and some of the policies that have emerged as a result of that.
Todd: And I guess it feels like, from a regulatory side — and I'm not going to pretend to be an expert here — it does feel as though there's a need to try to shoehorn chemicals that fall outside the applicability domain into this hazard classification scheme, as a way to maintain this approach of regulating chemicals in the marketplace.
At the same time, as I've been listening to your podcast, what really strikes me is the amount of money that's at play here in terms of testing requirements — how much industry has to spend and how much it takes to get a chemical to market. Is the added benefit — the protection of human health and the environment — is that benefit large enough to warrant the amount of money being spent? Or can we try to reflect on the ability to do risk assessment? If you're using a persistent chemical at low tonnage, does it really represent a risk to human health and the environment?
Now we can argue that if we continue to use those chemicals it could be a problem in the future, so we should act now to prevent that accumulation from occurring. But at the same time, if I think about the chemicals we use today, they're not the same chemicals we used 50 years ago or 20 years ago. And so I would anticipate a lot of innovation occurring in the next 20 years. I would challenge a little bit the business-as-usual model, because I think there will always be innovation. Even today, with the discussions on persistence and mobility, chemical companies are going to have to innovate out of those technologies and replace them with something else that hopefully benefits society and the environment moving forward.
But at the same time, we want to ensure we avoid a different kind of regrettable substitution — not necessarily just getting rid of something that's bad today, but putting something in place that may represent different hazards in the future, which we'll then have to shoehorn different approaches to screen for. Because there will always be something that happens in the future that we can't anticipate today.
I think it's naive to begin to think that we can actually create something that is safe and sustainable by design — those are also human constructions that are based on our current understanding of what we define as being safe and sustainable. And that seems to change as we move forward. The goalposts in the regulatory space are always moving. And I can appreciate from the chemical industry side that there's some frustration with that, because we have OECD tools, test systems and approaches — and those test systems are not always going to be appropriate for the chemistry that moves forward. We will need to adjust and change. But it's such a big bureaucratic system that it seems challenging for it to be flexible enough to move with innovation going forward. And so I think this potentially represents a different kind of challenge, perhaps, for society.
Chris: Yes, and just reflecting on what you were saying about the new concerns arising around persistent and mobile chemicals — this is not news. Any environmental scientist or regulatory person working in this area would have known for a long time that in human society we use a lot of chemicals, we enjoy a very high standard of living, and in the course of using those chemicals they can be emitted to the environment and potentially cause an impact — either on the environment or, in some cases, making their way back to people and potentially cause harm in that respect.
That shouldn't be news to anybody who's been working in this field. And it feels to me like the whole consensus that has been built amongst experts — governments, academia, and industry scientists — has been in place for many years. But now that we're talking about sustainability and trying to respond to things like climate change, which is caused by CO2 emissions from human activity, we're revisiting a lot of decisions that have been made in the past and a lot of previously held consensus.
And also with respect to exposome, I do wonder whether part of the problem we are going to face is that the public was never included in these discussions, because they're very technical and complex and difficult to understand. But to a degree the public is involved, because these chemicals are getting into their bodies and that is alarming to people who don't understand the risks. So to what extent do you think there is a need to get a better understanding of this out there — the state of modern society with respect to chemicals?
Todd: The questions and the answers are not black and white. There's a lot of grey in there, and some of the things we're hearing in the media don't necessarily reflect real risk or concern. That is more a social science space — how the media covers a lot of these topics. 'Forever chemicals', as you mentioned earlier, invokes an emotional response in people because it sounds very negative. Of course, it makes a great headline to put up front: you have these forever chemicals accumulating in our bodies and we should all be afraid of this. So I think for the general public there's a consumption of a lot of negative news that comes through.
There's also a bias, I think, in the peer-reviewed scientific literature — particularly on the environmental science and chemistry side — which really promotes the generation of results that are negative. If you're a PhD student running a toxicity study and you get no result, that's not a very attractive thing to put in your thesis. It's much more exciting to find a negative effect. So we do have a publication bias where negative results get published a lot more than positive results that show no adverse effect. I think those studies exist — perhaps a lot of them are within companies, or in the grey literature — and we just don't see or hear about those positive stories.
This goes back to the question of exposure. We have all these chemicals in us — but taking more of an exposure scientist perspective: I was struck when I came across Paracelsus and learnt — as I guess all toxicologists should be familiar with — the concept that all chemicals are toxic, there are none that are safe – and I'm paraphrasing of course – it’s the dose makes the difference between a chemical being a toxin and providing a benefit. So as long as our bodies are able to clear and eliminate the chemicals we're being exposed to, the body is doing its job. Because even if we're talking about synthetic chemicals, there are also naturally occurring chemicals that our bodies have to deal with and eliminate. Chemicals are in everything, and if we eat certain foods, there are chemicals that are not necessarily good for us that the body has to deal with. And so we have evolved to sort of deal with these things.
I guess I've come through a path where I've learned a lot of these aspects and feel more comfortable with being exposed to chemicals at lower doses, because I'm not recognising a risk. I think we have learned a lot since the 1970s, when there were occupational exposures with no health and safety in place and people were exposed to very toxic levels of chemicals, which led to a lot of problems. There are a lot of industries we're familiar with where people were exposed to chemicals and ended up getting cancers as a result of their exposure to those chemicals later in life. We now have a lot of occupational safety protocol in place to protect people from those exposures.
And I think what we don't hear a lot about is how much better a lot of our exposure to these chemicals has become. There's an improvement that we can begin to see. I'm reflecting on some papers that came out of a group here in the UK — the UKCEH — led, in part, by Andrew Johnson, whose recent publication was questioning a little bit how we do risk assessment. The approach of comparing a PNEC — the predicted no effect concentration — to a predicted exposure concentration, and deriving a risk characterisation ratio: if you exceed one, you have a potential risk; if you're below one, there's no risk. But what if you're 1.1? What if you're 0.9?
I think the really valuable thing Andrew Johnson has been doing is actually looking at the environment — do we see impacts on ecosystems? And if you look at ecosystem health, you see fish populations rebounding from the 1970s and systems looking a lot better. His most recent publication attributes this particularly to metals — copper and zinc, for instance — which were being emitted into waterways and representing an exposure risk for organisms. But once you were able to control the release of those metals, you began to see populations recovering.
It's curious because here in the UK we have a lot of talk about direct discharges from water companies into waterways and people being concerned about that, and yet macroinvertebrate life in the rivers does not seem to be negatively impacted, at least based on the population data available. So again, there seem to be different ways of thinking about how we can evaluate risk — focusing on hazard characteristics and not actually looking at what we see in the environment is perhaps a missed opportunity. Because we could do a better job of evaluating risk, and if we could communicate positive news stories, that might help ease public anxiety around exposure to certain chemicals. Because I agree that consumers who are focusing on this topic have a high level of anxiety. Whether or not this represents a real risk is not well communicated, and there's a confusion between hazard properties and what is and isn't a risk.
Chris: Yeah, you raise a few interesting points, Todd, and we'll see how this conversation evolves — it's difficult to keep all the threads together. You're somebody who brings a lot of interesting thoughts and ideas to the table. I did want to ask you — you made reference to that study by Andrew Johnson. In the general media we hear a lot about biodiversity loss as a huge global issue. How does that tally with the findings of that study? Because you and I, as environmental chemists, are very interested in the fate of chemicals, where they go, and whether they can potentially cause harm. But then there are these macro indicators that come out of ecology, and somebody somewhere needs to try to connect these things up — and it doesn't happen very well. When I hear authoritative reports saying that global biodiversity is in decline, that's obviously quite concerning.
Todd: Yeah, I think you're bringing to mind the benefits of multidisciplinary expertise in speaking to some of the issues we're dealing with. When we're talking about chemicals, we tend to have just environmental chemists and toxicologists talking amongst themselves and not necessarily going outside the silo to bring in information from other sources.
One of the challenges in understanding the broader context is that it's not just chemical stressors but non-chemical stressors when it comes to biodiversity. Now I'm not going to pretend to be an expert on the topic, but it seems to me that I'd struggle to suggest that the reason for potential biodiversity loss is primarily due to chemicals. It seems to me that human behaviour is a big component. If you build a road, you're impacting the environment in which you're putting the road. You're reducing the biodiversity of that system — and yet we all benefit from roads, and we're not complaining about the impact that roads are having on biodiversity at a large scale.
Are we really just going to blame this on chemicals? It seems to be a very small part of the bigger story. But this starts to go into a more ideological component: how do we want society to progress moving forward? We still want to develop as a society, we want to have a small impact on the world around us — how do we balance these things? You want a car, you want to drive to different places, you want to go on holiday. All of those, of course, have an impact on the system. You want to go and see the Great Barrier Reef? Well, you're going to have an impact, because that's a non-chemical stressor. Noise, people — are the species that live in that system happy that you're there? We're happy we're there, but we don't seem to be reflecting on the fact that our presence is itself a negative on the environment. But we are also part of the environment. So we have to identify how we can hopefully strike a balance between these two worlds — though this is more ideological and philosophical, I guess.
A number of years ago I had a great opportunity to become familiar with Dynamic Energy Budget, or DEB, modelling — models developed by Bas Kooijman at Vrije Universiteit Amsterdam, with whom Tjalling Jager was also working. It was a sort of experience along the lines of meeting someone like Don Mackay — he was a fascinating person to talk to. The models could be used and applied in various contexts, including for chemicals. And the principle, for someone who never really did any biology in their undergrad, was that I began to understand how these models work because it all came down to energy.
Organisms need energy to grow and to reproduce. Within these models, the idea is that if you have a chemical stressor, the reason you have an impact on growth and reproduction is because the organism is investing energy to deal with that stressor. That could be a chemical stressor or a non-chemical stressor — changes in temperature, for instance, for a fish, are an important stressor. So you can develop a model to help you understand the impact that these stressors might have on different populations. This is applied, for instance, in fisheries management — you could use this model to maintain and sustain a fish population if you understand the different stressors impacting it and try to ensure that the energy in the system is sufficient for the organisms. It can also be applied to human health, and there have been examples of that.
And again, thinking about what Andrew Johnson is doing — it's sort of trying to take what we actually see in the world and apply that to ensure we are protecting the environment from the different causes that are occurring. I do think that, in terms of ecosystem harm, chemicals are a smaller part of the story. It seems to me that human behaviour more broadly is a big component, and it's more ideological and philosophical — how do we want society to progress while hopefully striking a balance with the natural world?
Chris: On persistence — if we could go back to that topic briefly — one of the challenges we have is that we've designed this framework to evaluate persistence, which is informed by degradation half-lives in different environmental compartments.
So we've set up a kind of sausage machine that will look at substances one by one, look at the data available, and make a decision. And we've just expanded the scope of that sausage machine to include chemicals that are more hydrophilic — rather than just the hydrophobic chemicals — and also chemicals that are perhaps not subject to registration under REACH, such as polymers and low-tonnage substances.
But one of the issues we have is that the data required to plug into that determination — the half-lives for these chemicals — are generally not available. And there are good reasons why those data are not available. For a long time, we've been satisfied to screen biodegradability of chemicals to look for those that are readily biodegradable versus not, and we focused our attention on chemicals that are more hydrophobic because historically those fit the profile of the PBT/POP chemicals, which have been accepted as the more problematic ones.
What we have now is a situation where all these chemicals are coming into scope for these assessments without the data being available, which will leave a big open question as to which chemicals are ultimately going to be found persistent — causing a lot of frustration for those who want to see action on persistence, but also a lot of uncertainty for companies that want to innovate and find new applications, because they don't know if their chemicals are ultimately going to be found to meet the criteria for one of these hazards.
Another thing worth mentioning is that there are issues with the tests used to assess persistence, such as high variability — a natural product of the test systems, which use an environmental sample to which you add a chemical and watch how quickly it degrades. Which I think goes to what you were saying earlier about whether persistence is an intrinsic property of chemicals and how we should ultimately deal with that.
And I'll probably also just address a conversation we were having before the podcast about the article I wrote about persistence, where I was basically advocating that industry takes this issue very seriously. You were questioning whether persistence as a property was the be-all and end-all of concern for chemicals. And whilst I agree with your perspective that persistence is one aspect of a chemical's overall profile that could lead it to cause concern, the purpose of that article was also to educate and inform people who might have responsibilities under regulation to carry out these kinds of assessments — to tell them this issue was coming — and to provide some analysis of the current policy to try to forecast the impacts that could arise.
I'm also trying to tease this out in the discussions within the podcast, because in the absence of this data, we can only really speculate on what the impacts might be. But you can look at what it says in the regulation and in the guidance in terms of how things are meant to be assessed, and you can see the overall direction of travel. My feeling is that we've constructed this sausage machine but we haven't yet got it to work on the chemicals that are on the market. ECHA has been issuing decision letters to get more of this kind of data generated, but it's in the pipeline — the data hasn't emerged, and the final decisions can't be taken.
I'll also say a couple of other points I wanted to raise in that article. The first one is that, aside from whether it's right or wrong that persistence becomes an overall defining issue, this is linked to public perception around chemicals. A lot of pressure comes on companies that sell into consumer markets — because when you use a shower gel or a toothpaste, the formulation you're using for your personal needs is generally emitted down the drain, into wastewater treatment infrastructure, and may well find its way out into the environment. And naturally, members of the public don't want to think of themselves as polluting the environment. Littering is generally not acceptable from a societal perspective, and I think that is coming through in the public consciousness. Companies — such as those in the cosmetics industry and the home care industry — are responding to that in a big way, for example on soluble polymers, which serve a very important function in a lot of these applications.
And the last point, which is more of a meta, overarching philosophical one: as we talk about sustainability as an overarching challenge, if you are emitting chemicals to the environment that aren't degrading, by definition, can that be seen as a sustainable activity? I guess it depends on how you define sustainability.
Todd: Yeah, so there are many things in there. We do have a little bit to reflect on in terms of the use of the chemicals we have. You mentioned in your podcast Unilever committing to having biodegradable ingredients in their products by a certain time, and so this is an approach to address concerns from the consumer perspective. Companies like Unilever and Procter & Gamble are the face of a lot of these products, because consumers are buying them and they take this very seriously in terms of ensuring that what they put on the market is acceptable to consumers. And if you're using a shampoo, I'm sure that as a consumer you're not happy about the thought that the waste you're emitting down the drain is potentially going to last in the environment for long periods of time.
So I think these are very important considerations that need to be reflected upon. However, there are different use scenarios where persistence is a valuable property. I'm very happy that my laptop has persistent components within it, because if it were falling apart and I had to replace it on a regular basis, that's rather counter to the whole concept of sustainability. And we have regulations in place that have different safety components — flame retardancy, for instance. If you have a sofa in your house, this is where we come back to the issue of polybrominated diphenyl ethers, which have properties of persistence, bioaccumulation, and toxicity — they're PBTs. But at the same time, they play an important role because they help prevent fire and can prevent fire deaths. So they're very important, and there's a whole regulatory space that wants those products to be safe for human use. You do not want a biodegradable flame retardant in your sofa, because then you'd have to reapply it regularly to maintain the fire retardancy.
Now, there could be other ways to incorporate flame retardancy using physical approaches — different innovations that could come into play that don't require the use of chemicals for that function. But there are so many uses of chemicals in society — in infrastructure, buildings, materials. Chemicals are in the wood here around us, this wood is treated, and there are aspects of that where you would want persistency associated with the life of the product.
I guess the challenge is what you do at the end of the life of products — that's where we want to recover them. So we want something that's persistent through that lifetime, but how do we then incorporate some sort of circularity in terms of product design? And I know you had Libby talking about the apparel industry and trying to address some of those concerns — fast fashion, for instance. If I buy a shirt, I want that shirt to last on the order of years. I do not want it to be falling apart after one year. So my preference is for the persistency of the product in that context. This could take us down the road of thinking about the use scenario — where persistency is a benefit to have in a product to maintain the sustainability that we have, and I think circularity plays an important role within that context.
Again, this is a different set of experts that need to come around the table — material scientists, formulation scientists. If you're going to put biodegradable chemicals into a shampoo and have them all biodegradable, how does that change the efficacy of the product? There's a shelf-life aspect. There are a lot of issues to consider, and you need very special expertise to address those concerns. I'm not sure environmental chemists and ecotoxicologists are the best people to speak to all the challenges that fit into that space. I would prefer to have the right people at the table.
We mentioned the value that can be added from multidisciplinary expertise in addressing these very complex problems, because these are not simple solutions. There's not a case of just trading one chemical in for another — we may have to substitute or add three more chemicals to get the same functionality, and biodegradability in that case may not be the best option.
The other aspect — thinking outside the box a bit — is our wastewater treatment facilities, which were initially designed to remove BOD, the biological oxygen demand that is potentially input into the riverine or aquatic system receiving the wastewater treatment. We don't want to directly discharge our human waste into waterways, because that would kill all the life there by depleting the oxygen. So treatment plants were designed to remove that element. But what we've done over the last 50 years is put a lot of chemicals into everyday products that go down the drain, for which the hydrological residence time of the wastewater treatment system means they're not degrading in a sufficient amount of time — or the fate of those chemicals is potentially sorption to biosolids. And what do we do with the biosolids afterwards? So again, innovation could potentially play an important role in helping us to get out of perhaps some of the problems or challenges we have.
I guess I'm finding the arguments around the hazard properties of persistence, bioaccumulation, and mobility too simplistic — they don't address all of the aspects of how we use chemicals in society. And again, as I've been listening to your podcast, what is striking me is the amount of cost involved in substituting these chemicals. This is not trivial. Industries are going to go under, potentially. You're going to lose jobs. There's a lot at stake. There's a socioeconomic component of this that needs to be very carefully considered.
I just do the environmental chemistry side, but I worry a little bit about whether all of these other aspects are fully reflected upon. It's more a life-cycle way of thinking about the bigger picture. And that's where you do need to have the right expertise — a lot of people coming in and contributing to that discussion. Industry, I think, is valuable in this space — particularly large companies, because they do have a lot of experts in different fields. The challenge I experienced at Unilever, at least, was that there are silos within the companies. You're not necessarily getting the formulation chemists talking to the ecotoxicologists, who don't talk to the human toxicologists. Everyone is doing their own little thing, because the companies are so large. You don't have this crosstalk that can help to address some of these challenges.
If industry can identify and recognise that it has this in-house expertise and create a system that brings these people together in a constructive way, it could be very beneficial to addressing some of these challenges. But whether public pressure is so high that we just have a knee-jerk response to what we're hearing and ban everything — that may limit the benefits that could come from innovation. I guess I worry about that. At the same time, I appreciate the concerns that are being raised. But how can we think more holistically about all of these things? I think we would all benefit if we really sat down and thought through what we're doing.
Chris: I think that's a very considered viewpoint you've put forward. And reflecting on how that vision could be realised — I think there are some big challenges ahead of it, because industry in general seems to be hurting right now and firefighting when it comes to regulatory and compliance challenges. There's been a lot of complaining around the regulatory burden, which has perhaps led to some of the discussions around simplification. But I think what you're pointing to is a much bigger assessment or rethink of what we're doing in terms of how we're managing chemicals and the direction of travel we're heading in.
And perhaps when we get to the finishing line of that overall process, we may not be particularly satisfied with the results. I think that persistence is probably holding some of this at bay because of the data gap that currently exists for a lot of chemicals, and also just the administrative burden of working through these assessments, which ultimately do take time. But I think you and I can see that there's a pretty treacherous potential outcome here.
There is, of course, the need to think about things more in terms of multi-issue and multidisciplinary challenges rather than black-and-white issues, and to consider those trade-offs. Silos have been a problem for many years, and they dog many different enterprises — but in particular the scientific enterprise. People are talking a lot about multidisciplinary interactions and that's the sort of direction to go. And as we move into a more complex world, that seems to be where the new gains will be made. I wonder how technology could help us in addressing some of those aspects. But for today, we're more kind of providing an analysis — and a pretty pessimistic analysis to some extent, I would say.
Todd: Well, I mean, it's good to voice concerns that might sound cynical or pessimistic, but at the same time we should appreciate that we're all, regardless of what we want to move forward, we are all wanting the same thing. We’re rowing in the same direction. I don't think there are those working against anything — I think we all want betterment for human health and the environment.
As you have this Charles Mann book here — we were talking about some of these issues in terms of innovation and technology. He wrote this book called The Wizard and the Prophet, which I stumbled upon a number of years ago and thought was quite an interesting read. Because there are different approaches to dealing with issues: there are those who see things from one perspective — can technology be useful in terms of helping to solve our way out of the issues we face? — and those from another who perhaps reflect upon a more cautious outlook and try to address the problem from a different angle, which is more around restricting activities.
In this particular case the book focuses on the Green Revolution. Prior to the Green Revolution there was a sort of understanding that the carrying capacity of the planet could not maintain the growth in human population in terms of food supplies, which speaks to the need to reduce population. There are other books — The Population Bomb and so on — and we've been, I think, as a species concerned about human population and the ability for the planet to sustain us. If the planet's population is 9 billion people, how are we going to continue to feed and clothe and do all of these things if we're not going to use chemicals? Chemicals play a really important role. And at least in the Green Revolution, chemicals were really important in terms of helping to increase productivity through the use of fertilisers.
So I think innovation can play an important role in demonstrating that there are challenges we face that we can solve. But we should not necessarily muzzle or restrict the other voices that are also raising concerns — I think there is value in all of these discussions. There are no easy answers.
As we're talking about all of this, it feels like the sort of conversation you might have at SETAC at the pub later in the evening, where you ramble on and on and try to solve all the world's problems and really don't. But it's helpful to get those thoughts out and articulate what we're facing on a day-to-day basis, and through that conversation hopefully we work towards coming up with different approaches to addressing the challenges we have.
There are a lot of different perspectives, which all have value. We just should be open to exploring how we can implement those. I've mentioned different tools that I've found attractive — DEB modelling, for instance. I think Andrew Johnson's work is quite informative and positive. We can actually improve the world we're living in by identifying what the biggest problems are.
My worry is that we're spending a lot of money and concern on issues that, if we change them, may only have an incremental impact on improving where we're at. I kind of wonder if a lot of the things we're talking about now are incremental, whereas perhaps all the biggest improvements we've seen in the environment have already resulted from reducing metal pollution. Today, from a human health perspective, air pollution — particulates generated from automotive emissions, for instance — represents a cause for concern. Technology can help us reduce the amount of particulates and benefit human health. So I'm optimistic, actually, that innovation is already happening, and that there are a lot of promising things that will improve the situation. Even those you've talked to — Claire, Libby — have pointed to some promising advancements taking place. And a lot of smart people seem to be giving this thought. Paul Thomas, Peter Fisk — how can they help to inform the decision-making process in terms of evaluating risk and hazard associated with chemicals? Those are promising approaches, and I think there's a lot of added value in terms of where we're going moving forward.
So I'm optimistic overall. And, hopefully, as we were talking about earlier — we become more open to challenging each other in constructive ways, not destructive ways.
Chris: Thank you, Todd. I think that's a lovely way to conclude our conversation, unless you have any final remarks.
Todd: No, it was fantastic. Thank you very much.
Chris: It was really good. And thank you as well for introducing me to this book. I have to credit you — it is a fantastically well-written book, which gives a very easy-to-comprehend account of the lives of two people, and really frames a lot of the discussions and perspectives we encounter in our work. So yeah, I've learned a lot from you and I hope to continue in the future. But thanks very much. And thanks to everybody who's been tuning in today — your time is really precious, so I'm really pleased you've spent it with us. I hope you've enjoyed this podcast and found it insightful. I look forward to catching up with you next time. This has been Chemical Journeys. Thank you very much.
