 Well, thanks everyone for joining us today for Hydrotera's first webinar of 2024. It's great to see so many registrants today and thanks very much for your continued interest. Today we have a topic which is close to my heart really. It's all about contaminated land. The title being decoding 13 years of audits, unveiling health risks from contaminated land and its implications for policy, research and practice. I guess one could paraphrase that and say we're doing a lot of work in contaminated land. How well is that work working and how important is it? Today's presenter is Dr Victor Cabay. Cabay, correct. Thank you Victor, you've got to stay out of this stage. So Victor, I will introduce more formally and give a background in a second. Before that I'd like to acknowledge, I'd start by, I'd like to begin by acknowledging that we conduct our work across this great land and for that privilege we would like to thank the traditional owners. Hydrotera respectfully acknowledges the Boon Wurrung people of the Kulin Nation where we are located today and we pay our respects to their elders past, present and emerging. There's a picture of Victor. So a little bit about Victor. He's an environmental risk management specialist with over 20 years experience consulting about his state government, industry and academia. He currently works as a National Senior Environmental Advisor for Cleanaway and has been recently made a fellow of the University of Melbourne in acknowledgement for his ongoing support of the university and in particular CAPM, which stands for the Centre for Anthropogenic Pollution, Impact and Management. Some of you would have seen Suzie Reichman's talk last year which took out the prize for the most attendees. A few more things about Victor that I've just learned from him. He did his undergrad, his masters and his PhD all at the University of Melbourne. He's had a strong focus on gasworks and contamination associated with him. He was for five years the Principal of Public Health at the Victorian EPA and he is currently a Senior Environmental Advisor with Cleanaway focusing on risk management frameworks and incident management. So really lucky to have you here today Victor and thanks very much. Before we charge into things just to remind you that we have a desire for you to ask lots of questions and in order for you to do that during the presentation please use the Q&A button at the top of your screen. It's a really important part of these webinars. Why does Hydrotera do these webinars? We believe in sharing knowledge. We like to facilitate education and we like to take a leadership role in industry. So without further ado I'd like to pass over to Victor. Excellent. Thank you very much Richard and thank you everyone for having me. Before we start I just want to very quickly think you know obviously Cleanaway have been and continue to be wonderfully supportive of all the quirky work I do outside of my role at Cleanaway when I volunteer for the university and I really want to thank them for that. And everything I'm saying and doing today is really with my Melbourne University hat on. So it really doesn't represent anything at the Cleanaway and it is very much as a fellow of the Melbourne University. If you could go to the next slide please. What we're presenting today or what you will be hearing from me today is it's all published in quite a recent paper which you can see there on the right of the screen. And I obviously have to acknowledge my two absolutely wonderful co-authors being Claire Papaleo who works at WSP and she's a brilliant risk assessor and fantastic statistician. Anyone who has worked with her knows and she's one of the only people I know who's actually passionate about statistics and enjoys it. And of course the magnificent Susie Reichman who is the director of the CAPM and has been a colleague for many years and a wonderful person and a brilliant co-author. So I thank them both very much. So what is this piece of research you're going to hear about today? It came as an unusual idea from me. It was to look at many years of audit reports from Victoria and and try and extract risk data from these audits. And you know these audits they just tend to sit somewhere right and we said no no no let's actually go back and look at what they found in terms of human health risks and actually look at all the results together. And try to see what they could tell us about the risks posed to human health by contaminated land overall and also really help us understand about the machinery of how contaminated land is managed. What is the risk framework in Australia for how contaminated land is managed? So if you can go to the next slide please. Basically you know it was an it was an ordeal and actually this project got me through COVID because even when you're reviewing 1,764 audit reports you know it's great to be sitting on the couch at home and not being outside. So this project was it was a little bit of a COVID project and it definitely did its job from that perspective. One thing I will say by the way for obviously there's many people in the room who are not from Victoria. Obviously Victoria has a contaminated land audit framework they've had it for many many years and actually most are all states in Australia have something comparable. So the reality is even though the results that I will be presenting today come from Victorian audits, chances are they're broadly applicable at almost all states in Australia or generally applicable everywhere throughout Australia and probably in most similar countries. So what have we been really looking for in in in these audit reports so sure we're here 1,732 audit reports. We did not extract the concentration of every pollutant from every report no we did not do that. What I was really looking for was any audit report that had a health a human health risk assessment component to it. Whether it was done by the auditor itself or whether it was one of the appended documents and one of the appendices to the audit. So, for those of you are not familiar human health risk assessment reports are basically an evaluation of you know if they take into account everything right all of the source pathway receptor explore pathways are considered various phases whether it's liquid solid gaseous. They look at all of the data holistically they look at all of the human receptors holistically and they try to provide relatively objective and we'll talk about it risk metrics to evaluate the risk posed by the site as it is, or as it would be after some sort of remediation. So, in searching for these health risk assessment reports from the audits, we extract that in total out of the 1000 however many it was if they ended up being 376 human health risk assessments that we could review in detail. Next slide please. Let's look at first for the first graph we go straight into the results because we why not when the results are the fun part right. So, we're looking at this these 13 years of data, and let's look at how many audits were done and how many of them had a risk assessment at all. This graph is mostly interesting to risk assesses and it tells you something about the state of the industry more in general. And please just for anyone out of state from from out of state, please remember in Victoria, the content land audits and the facilities audits as they were called a treated differently, which is why you can see that little peak in 2014 can you see that not contaminated land audit peaks up. That's a false peak. Please don't treat it as a real peak. That is just because that is the year when API uploaded them all onto the system. All right, so that's when they started uploading them before then there were a facilities audits or non contaminated land audits, but they were not uploaded onto the system. Really, there isn't that much of a pattern in this graph but there are two stories that I'd like to tell. One is there is a slight peak a couple of years after the new nephem came out in the audits, whether that's, you know, a causal link or not is a little bit hard to tell but it's an interesting one to point out. And the second one that I'm most interested in is that about 30% 35% of audits have a human health risk assessment component to them. And that hasn't changed through time. I mean, of course, it goes up and down a little bit, but it's basically always been the same. This is actually quite a surprising finding. I thought that with the new nephem coming out and with all the focus on risk assessment that that number would have got ramped up or it didn't. It's essentially the same the whole way through. Next slide please. So let's think about it for a second. Okay, when does someone even do a health risk assessment right. A health risk assessment. There's a million situations when you do one let's be honest so I can't tell you the full picture will just tell you some of the main ones. Usually, it's when you've got a pollutant or more than one polluted that is present and it's detected at concentrations that are pretty high and definitely higher than the guideline values that are present in the nephem or in other guidelines, the screening level guidelines you apply to your starting point. So if you've got arsenic in the soil, that's fine. There is arsenic in almost every soil. But how much is there? Oh, there's levels that are above the screening level guidelines. All right, we probably should do a health risk assessment, especially if it's the site is proposed to be reused for quite a sensitive reuse. And there is a plausible exposure pathway to a sensitive human receptor. I suppose a second use of health risk assessments really is when there are no guideline values at all. So for example, when there is a pollutant that for which there are no screening values. Of course, and I forgot to list it in there, there is a third major use that is when, when you're trying to remediate a site, and you're defining your remediation targets that's normally done through a health risk assessment. Now, the lines below are a bit of a caveat because of course I can't not have caveats. So we're looking at data out of human health risk assessments. It's not what you would call a clean data set. It's an empirical data set. It is, it's the function of a lot of things. Okay, so, for example, if a pollutant is very expensive to analyze, you might not have analyzed for it so you wouldn't have detected it and so you wouldn't have known to the risk assessment of it. Right. And that's dioxins for anyone in the room. That's the example because they cost. Well, back when I worked in Contamland, there were about $1000 a pop for analysis. So that's one. You know, there also, there might be situations where the screening level is so conservative that you exceeded all the time. And so you're just going to carry out a lot of risk assessments to actually try and evaluate the risk. You might have some situations where the screening level is not very conservative at all. And so you actually, you almost never have to carry out a risk assessment on it. So, so you can understand what I'm trying to say here. This is not, it's not just a simple metric where everyone assesses health risk in exactly the same way that's a nice cold hard data set, but it still can teach us a lot about contaminated land. Next slide. So one of the objectives of this piece of work was really to try and guide planning policy. Right. And it was to understand, you know, what are the historical uses of land that are most likely to results to create a human health risk that is notable. And there's many ways you can look at it. So one way of looking at it is simply black and white of all the principle contaminating activities. That's what we're calling them. Which are the ones that needed a health risk assessment most often remembering what I said before when do you need a health risk assessment when there is going to be a sensitive receptor on the site and when you've got a polluted that's exceeding some level that triggers an initial red light that it might be amber light that it may be of concern. So if you look at the top six the next slide. If you look at the top six there they're interesting indicator of sites of principle contaminating activities that happen often often polluted and often have pollution levels that exceed guideline values right and that's a way of looking at it. So I would say and I often redevelop for sensitive usage. So it's actually quite an interesting way of looking at it and it's quite a plausible way of looking at important principle contaminating activities service stations shouldn't be a big surprise to anyone who works in content land service stations are way on top. Why is it you know they are they're surrounded by houses literally next door. They've almost always got a plan and it almost always moves underneath the residential nearby and there is a vaporist that creates a potentially complete exposure pathway. Filling for those of you who are not familiar by that I mean whenever you build a house you need to like set the foundations you need to you know create a nice flat ground and what you often do is you often get filled from somewhere else to do it. And historically people were not that great at checking how clean the Phil was before putting it in. In fact they often use gasworks waste as you know which means there was a lot of lead and a lot of poly aromatic hydrocarbons and other things. We will talk about online sources more a little bit later especially if we've got time but so it seems we have to have unknown in here but you will see what we mean. And then of course there is gasworks automotive repair and chemical manufacturing and of course all the other ones you know it's it's not a black or white it's a sliding scale. So if we look at the PCS this graph don't get too excited about it I'm presenting it literally to show there is no pattern. Okay, so I mean if you find one by all means let me know but they're really really isn't. So what this is trying to show is you would have thought that they would have been a peak for example in service station assessments earlier on and it would have come down through time as they would but slowly getting closed down that hasn't happened. There is literally no pattern in a temporal trend in which principal contaminating activities were assessed more often. Now, let's look at a different way of looking at risk okay so the first time was just a way it's an approach. But let's look at it in a in a different way here. So, if we look at, sorry, if we look at the probability that a risk assessment will be required. So, basically what I'm saying is if I'm a consultant and I set foot and I'm starting an audit on a guesswork site. Based on the data we've seen so far there's a 78% chance you will need a risk assessment for it, which means there is a 78% chance that it is highly polluted sensitive receptors nearby complete exposure pathways. It guidelines exceeded right, I have to be honest I actually thought it would be closer to 100 with guesswork sites but this is the this is the numbers that came up. So can you see how this is a different way of looking I will I will not give you clean answers I'm sorry unfortunately that's the nature of this research. It just depends on different ways of looking at the same thing. If you define the risk of of each principle contaminating activity as being the likelihood that you'll need a health risk assessment as part of the audit. Then guesswork strike cleaning and service stations come and let's say imported feel come out way on top. Right, and they make sense. They are they are polluting activities they are very, very frequent. They did you notice guesswork strike cleaning service stations are all related to vapor risks, often not always often. So it's quite a it is a significant finding and it is an important one. And anyway, and also for any consultants in the room this is useful so you know when you're getting into if you do start an audit on one of these sites. Next slide please. Now, going forward, so there are some that the next analysis is going to be a little bit more intricate. I don't expect anyone in the room or I don't expect everyone in the room to be a health risk assessor. It's quite a specialized little field that some people like myself like dedicated a lot of time to, but no one should be expected to get into that kind of stuff. I will be reporting to you on two health indices that are commonly used in health risk assessments. And for those of you who are not familiar it's actually useful for you to know this is how basically all environmental assessments are done are done using these two things. The first thing is called a hazard index. It's so simple. It basically says are you above or below a level that is in inverted commas safe. A real risk assessor never uses the word safe but you know I'll make an exception today. So you know you're drinking drinking water right and your levels of cyanide are detectable or God maybe not cyanide maybe something less toxic than that zinc. You know there's zinc in drinking water but it's within the drinking water guideline. If it is below the drinking water guideline you'll have an index that is less than one. If it is about if it's twice the drinking water guideline it will be two if it is 10 times higher the hazard index is 10. It's as simple as that. The second one's a bit more complex and I won't go into any detail with it. It's the incremental lifetime cancer risk. This was what's used throughout the industry. It every consultant uses this indirectly or indirectly to assess the risk of carcinogens. There is no such thing as just a zero risk of cancer. Every exposure contributes an amount of however small it is every exposure to a carcinogen rather. So every time someone walks out in the sun it slightly increases their chance of melanoma. It's just the way it works right and so it looks at this probability and it says when is it that you've reached the probability that is too high. And in Australia the official acceptable cancer risk is one in a hundred thousand. So I just thought I'd let you know so you've got the exposure that you're getting from drinking that water or living on that house or breathing that air is one in a hundred thousand. And if that number seems high please do remember to compare it against the standard incidence rate which ends up being about one in three. And I hope it's okay to share that but it's true that's the basic incidence rate for cancer in Australia. So I want to worry too much about the block points underneath if we can go to the next slide. And actually two slides, one more slide ahead if that's okay. This is a big busy slide please don't worry about it too much okay. This is what I really want to point out to you is that what I've done is I've really pointed it out. I've presented the data here as very low risk low risk which is acceptable both of those fall within acceptable criteria. And then moderate high very high which has you know basically you know yeah a little bit above high means you're 10 times above a safe level. And very high means you're at least a hundred times above a safe level right. So that's bad right when you're over a hundred times that's pretty bad. Of course there's a lot you could dissect here but ultimately what I'd like to really look at is underground tanks are fascinating there at the bottom in the middle. Those ones very often pose an unacceptable risk and are we surprised right to these underground tanks leak and they create often relatively large underground points. But I think it's useful to know it not once was a found to have was this use of land of these underground tanks where they found to pose a very high risk not once. And in just a couple of instances that were found to cause high so by which I mean about 10 to 100 times the safe level which is obviously still not great. But you know it's still significant. As for mechanical manufacturing and fuel storage depot why they are interesting is because of the relatively high presence of very high risks. Very high is a big deal. Right. And so you know it tells you something about even after all the assessments have been done after the risk assessor has refined their assessments and then all of the work that needed to be done. It's still ended up with a risk. There was a hundred times above acceptable risk. Now please understand this was done. These are all the assessments that happened before the audit, which means the audit obviously will have had a recommendation to do the remediation and the remediation would have then had to address those risks. Okay, so please understand exactly the context in which these estimates are provided. It's not like the audit just says, yep, the risk is a hundred times above. See you later and good luck. That's obviously never the outcome of an audit for any of you in the room who perhaps are not familiar with how it's like. So I just thought I'd dissect those three in particular obviously we could spend hours on this slide but we've done that but but I would not dare to boy you with that so if we go to the next slide. If we look at the, it's I suppose a way of sort of simplifying the previous slide. If you look at the numbers in orange. It is basically what I've done is I've presented. If I'm an auditor consultant or an assessor anyone. What foot on a site that used to be a service station that used to be a gasworks site. You know, what is the probability based on the data we have that that has a risk that is unacceptable, by which remain moderate high or very high that's what unacceptable means. And the ones in orange and you can see the percentages are presented there in that second column. The numbers in orange are the top three right that's a simple of that. And, and, and what is showing is so you know if I've got an underground tank, I am close to 60% sure that that tank would present an unacceptable risk if I did a risk assessment on it. That's what that's saying right. So it tells you something again about what are the uses of land but do you notice they don't quite overlap between different methods, which tells you something about how complicated it is to look at risks from contaminated land. So those fuel storage depots and underground tanks and mechanical manufacturers. Definitely you can see that there is something there about them potentially posing a significant risk to human health. If you look at the column on the far right, those are the, those are the ones that actually it's just a it's a it's a further breakdown. And these are just the risks that are very high. So what's the probability that if I set foot on that site and I did a health risk assessment that he would find a risk that is 100 times what it is an acceptable level of risk, which is a lot. And the fuel storage depots when this dubious award 30% right which is really quite high. If you want to look at it that way, and then you can look at the other numbers that they have to be to look at. So good to the next slide. This is my qualitative attempt right you've seen it right we're not comparing apples with apples here. What we've done it seems like a messy story and maybe in some ways it is, but in actual fact it tells us a lot about the state of contaminated land in Victoria and frankly in Australia right and the risk that it poses to the community. What you see what you see in this table is me trying to summarize the four methods that I've presented to you before. And, and basically just say in red is that the one that presented the top risk and then in orange ones are a little bit below and then in green the ones below that again. What you see, you know, you know you can you can say that service stations, gasworks, mechanical manufacturing storage depots. They, and to an extent important fill are significant in terms of their ability to contaminate land to an extent they will pose a plausible risk to human health. That's basically what we're finding here right and I think it is. And this is of course within all the caveats that I said earlier but it's still it's it is a very. It is a fascinating finding to me at least in its own way. If you go to the next slide, we look at something quite different don't get scared. This is a huge list, and I do not I will I will now read through every single camera objecting I will of course I wouldn't. This is, it is for actually for the researchers in the room in particular but not just for you guys and girls. There is, it's quite an interesting finding about what are the pollutants that get risk assessed most often. Right, by which I mean the ones that exceed their guidelines most often that are found most often that pose a concern the most often there is a million reasons why they might be selected. Right, but regardless for whatever reason a risk assessor came along and said, I need to do a risk assessment about that. Right, so that's and there is a many reasons why they might do it. So you can see the very top right in the top two. There's no surprises there they're associated with petroleum right fuel often with diesel and petrol right service stations but not just. Right, and these are common pollutants anyone who works in content land you'll see them a thousand times. So it's not that surprising to see them there. And remember, I just thought I'd say there's me reason as I said why pollutant would be on this list. And remember I said at the very start pollutants that have a very conservative screening value will be assessed more often. And that is true, potentially of some of the pollutants here. So for example, for those of you who work in the industry, trichloroethene which is in that second line you can sort of see towards the end of that 20 to 30 line or trichloroethylene as it is known to some that it's its old name. That is a substance for that's notorious for having a very conservative screening level guideline screening guideline value, which is why it was not surprised to see it here. Some would argue Ben's life hiring also has a very conservative guideline value. And so it's again not that surprising to find it here. Well, we'll talk to researchers in a second but for any policymakers in the room, like the values that are in gray. Or you know with a great highlight on them. They are the ones for which there is no guideline value in the nepo. It doesn't mean there is no guideline value at all. It's often buried somewhere else, but there is none in the nepo. And so it tells you something about what are the pollutants for which industry would love to have a guideline value. That's exactly what this table says. For the trimethylbenzene that are very common in fuels, the heavy fraction petroleum hydrocarbons that's the C 34 to 40. There are things like lubricants that are that sort of thing that very, very heavy hydrocarbons and the trans one to the chloroethene which is an old solvent that is often seen in all the industrial sites it was it was used. It was frequently found as a solvent. These ones are significant they are they are found often, they are risk assessed often, and they don't have a screening level guideline in the nepo. I should have said sorry for those of you in the room who are not familiar I should have said it sorry. The next item stands for the national environment protection measure which is the framework that governs all contaminated land assessment for all of Australia. We're really lucky we've got one for all of Australia rather than one in each state which would have been a lot more annoying or difficult to learn. For the, I suppose more the researchers in the room. Some of these pollutants don't have guideline values because there isn't enough research on how toxic they are. Right, and so that is something that I'll just raise with you like the heavy fraction hydrocarbons is definitely one of them, at least that I know of but there are there are many many in that list underneath. And this table is found in my paper which is open source anyone can access that paper anytime. So you don't have to buy it or anything crazy like that. So it's just something for you to think of and be aware of. So if we go to the next slide. Just before we do Victor. So you say very conservative screening value like yes definition there, which is pretty important right there's an opinion there. Why are you calling them very conservative do you not believe are they calculated in a different way or have you assessed the methodology through how they're created or have they got a different risk factor that comes into it. Look, it is an opinion. Right. And that is, and it's absolutely true you are right. And when it comes for example to the chlorinated hydrocarbons, even the nephem recognises like they're called interim screening values like even the nephem recognises in its wording that they are deliberately designed to be extremely conservative. And, you know, you know, and of course it would be possible to go into the detail of exactly why they're conservative and I would say with those. For any of you who work in vapor intrusion, you know it's the attenuation factor used, which basically looks at how much the vapor dilutes between the sub slab and the inside of the house. For that, that there's a number called the attenuation factor which is basically one divided by the other. And it is not it is broadly known that a relatively conservative attenuation factor was used as part of the nephem. So that is definitely an example of that. I might actually if that's okay Richard give an example of a pollutant that's actually the other way around, which is lead lead is actually not. It's one where the screening level isn't particularly conservative. Right, so any good risk assessor knows that they should never do a risk assessment of lead, because they will always find the risk that's higher than if they just applied the nephem. And there's that there's reasons for that. And it's because, you know, straight in Victoria at least or I think in Australia the acceptable blood, the know, the notifiable blood lead level in people has dropped since the publication of the nephem. We could talk about it for hours. The reality is the risk of lead is exactly the same as it's always been. It's just in Australia decision was made to actually drop that level so that the government would receive would be informed more often of when people have elevated blood lead concentrations. I hope that addresses your question Richard. I'm going to go with Victor for the moment. Yes, to some degree. So just one more question that's quite a big comprehensive list at the bottom here. But it's maybe 0.0001% of all contaminants out there. You really think it's meaningful, right? Do you think that list actually does truly reflect what compounds are risks or are we kidding ourselves that we have the full suite? This is actually a really interesting question. What that list at the bottom does, it doesn't tell you anything about risk. Let's be honest with ourselves. What it does is it tells you what are all the substances, all the substances for which in this 13 year period, someone wished there was a guideline value, or and there wasn't one, which you can see that's why there are there's all these great ones. Or there was a guideline value that was exceeded, but very rarely, right, just once or twice. So that is really what that is saying that is really about substances that are detected. That is what that is about. So it is hardly a hit list as such. It is about substances that are more infrequent. But it doesn't make them unimportant. It means that infrequent, they often don't have a guideline value, but at least once, but often more than once, they caused one of the assessors to say, no, that's it. We need to do a full assessment on this because I'm concerned that this might pose a risk. Right, so this tells you nothing about frequency, but it tells you there was at least one. That's what it tells you. All right, shall I move to the next slide? Yes, please. Thank you. Now, I would not, I will not go into too much detail into this analysis. So what I'll explain is I love multivariate statistics and my colleague who works on this paper with me also does. So that really helps in doing some dendrograms, which are the graphs you see, which is the graph you see here right now. What we were trying to do and achieved to some extent is to cluster the data that we found based on the principal contaminating activities and the pollutants that were found in these principal contaminating activities. So basically what it was trying to find is what are the telltale pollutants, I suppose, for various types of PCAs principal contaminating activities. And Richard, if you go to the next slide, there is a really obvious example there. You can see the first column, if you will cluster A is a number of audits and 100% of them were on mining and 100% of them were on arsenic. So that told you something about what in Victoria specifically and those of you from Victoria know what we are talking about it's from the gold, the old gold mining regions where there is a lot of arsenic in the soil. So it was historical gold mining and you can see, right, okay. It tells you something about how mining in Victoria is often associated with arsenic contamination. No surprises there in a Victorian context we knew that all along but it's nice when the data shows what you knew anyway. If you go one more ahead to the next slide. The next cluster is what I call the chlorinated cluster. And so it's really two clusters if you put them together, B and C. And so you can see and if you look at the road the bottom there is trichloroethylene, TCE, chloroethylene, PC, diachloroethylene, DC, you could see all of these. Right. And you could see where they occur. Right. And you could see that they are sourced by mechanical parts of manufacture a chemical manufacturer dryer cleaners no surprise no surprise no surprise. There is a very interesting one in there unknown. Unknown in the vast majority of cases the unknown principle contaminating activity when as in when the auditor literally could not name where the contamination was coming from was trichloroethylene. Why is that trichloroethylene is persistent in groundwater. It will travel long distances kilometers. Right. It was used it was widespread in its used in industry until not that long ago but long enough ago. And it was used in large amounts it was literally barrels would fall over would just go into the ground right. And, and, and so because of this, it is impossible to trace back the site where it's coming from original a lot of auditors I'm not able to do it it's just not possible. So, this is telling you something about how at most sites, having a bit of a concern, obviously, most sites near ish a formal industrial use let's be clear. If you're in an in a suburban environment where there's just been houses around you the whole time. There's no need to worry. I would say what this is showing is that chlorinated contamination is even if you had no ink that there was any contaminating activity really that near you. You literally can't even find where it's coming from. It's something that can pose a risk at your side. That validates. You know when auditors insist on looking at industrial use is quite a long way away when auditors insist on doing that groundwater well that perhaps that was like why are you doing it. Sometimes it's actually a very good idea to do it and this really validates that view that some auditors have. If you go to the next, the next slide sorry. That's what I call the imported fill cluster. And so that one is, you know, we talked before about open fillers when people historically not so much now would bring in unknowingly contaminated fill as the base of the house sometimes for the garden it would go over the place. And this one has just telltale pollution right it is bends away firing lead naphthalene benzene. Right. The Benzo parent and lead. They are like, they're a dead giveaway of ash from gas work sites which is a very, very common. It used to be a really common reuse of ash from gas work sites was just that feel from the environment of our houses because it was seen as a this is a long time ago it was seen as an inert material. It was relatively safe and I needed to put it somewhere. So that's what they did. Next one please. For the next one. So this one is the benzene cluster. So this one is you can see like, you know, 50% of this cluster is literally benzene found often with toluene I feel benzene. That's a common pattern we all know that. And it's obviously mostly from several stations right you can say it. There's really no great mystery here. Ultimately, this is the so far cluster, right, which we expected we knew it when we love it. You go to the next one. The next one. So this one is about heavy hydrocarbons right so we're we're cluster F is really about the light fraction hydrocarbons the ones you find in petrol, they move along, they move quite quickly. And they've operate. There's a vapor intrusion risk. This one is really about coal tar. That's about lubricants. And you could see it right it's gas works. It's still several stations there's lubricants and several stations, automotive repairs, no surprises there. Can you see that that's very much the pattern that you're saying here is that you can see how the pollutant is very much relating to the principle contaminating in these heavy hydrocarbons you can really see the the pH is coming up you can see the heavy fraction hydrocarbons you can see the benzene firing. And then if you go to the last slide. The last one is on light hydrocarbons in reality this one again has quite a lot of benzene quite a lot of service station, but this one is a little bit more of a mix than the previous service station that we've found. This one ended up being it's an interesting one this one is actually the most common cluster. And it's just saying it's BTECs f1f2 naphthane, you know those ones you always see them together right there's so so so common. And this is that cluster that is from all of that lots of service stations and lots of other sites where you can find petroleum hydrocarbons quite often. So no need I've already discussed this so we can skip this slide. So and this is the last slide of this presentation. So look, I really recommendation one way of looking at it but it's really just summarizing the findings so you can. This piece of research what it does is it it provides data to support a lot of things a lot of us already knew right and that's a good thing. We did not want to find crazy new things we wanted to be able to give numbers that policy makers planners would be able to use to justify some of the decisions. And some of the improvements that could be made at this at their levels or in the in the in the rounds or in the spheres of influence. Right, there's also a lot of information in here that is possible quite useful to consultants who operate in the industry. So they know when materials to prepare ahead of time because they know what pollutants are going to come up more often. I, I think there is you, has anyone noticed that PFAS was not in there. Now there was a reason for that the last pollutants was in the last audit that we looked at was in 2018 it was before PFAS had well and truly emerged right there was a couple in there but it was not very much. So please do not consider the lack of PFAS if we were to do the assessment now you just know PFAS would come up in there you just know it would. But this research still does say something about how researchers and I really I beseech all the researchers in the room, emerging contaminants. Yes, absolutely. Please keep doing the good work you're doing on emerging contaminants. But I would ask to please not forget the not so sexy pollutants that we perhaps have not addressed enough. I'll say it a million times petroleum hydrocarbons have not been studied enough. That's my view. Again, that's very much my opinion. But I think, you know, amazing things have been done to derive the very good quality guidelines that we have got now. But they did the best they could with research that was relatively limited. Right. And I honestly believe that we could do with more research on petroleum hydrocarbons especially given you've seen how common they are right there everywhere. So, and I think that's it for the moment I think that's why I'd like to wrap it up. And so thank you that's very that's all of it for me. Well that was excellent. Thanks Victor. I've got a couple of questions that I'd like to ask you before we get into it. Do you get do you think there's a bias depending on the auditors on which ones actually ask for human health risk assessments like others some that are sort of addicted to having them. I would say there's the ones who are addicted to not having them I'm joking that's not true. So I should I should know my audience better than that. There is absolutely and I, I know that for fact because I looked at I looked at that as part of my analysis, it isn't the same. The use of risk assessments changes between all it is there's a different reliance on them. And that's not that surprising right everyone has their favorite tools that they use to do their job. Absolutely it's incredibly common right and so if someone some auditors might do a risk assessment when it's maybe not really that necessary some might not have done one or perhaps it would have been a really good idea. There is no rule there is no moment when you have to do a risk assessment. It is a judgment based decision so it's actually perfectly fine for auditors to have different opinions on this I don't actually have a problem with it. I would also say that you know, you know one of the things that we found is that of course part of the decision does depend in part on whether the auditor has in house risk assessment expertise or not, and many of them don't. Right, which again is perfectly fine you know not everyone has a acid, acid mines drainage so expert in the house or not everyone has an asbestos expert in the house. But that is absolutely fine. Before we move past me. Back when I was more involved with doing this stuff. It always seemed to be a huge amount of importance in that attenuation number say cracks in the concrete likelihood of vapors entering a building. You do that risk assessment and every everything hinged on one paper at that time which you know. It seems to me in your comment earlier about very conservative screening values that it was still hinging on that so do you think that a primary source of research should be really nailing that down better. Look, the, the assessment in the NEPM is based on that the reality is that plenty of ways and risk assessors do this all the time in which they refine that estimate. So that attenuation factor has been refined a million times and right looking at site specific considerations of the shape of the building and the speed of the wind and the depth of the all sorts of things. Right. And so there is, you know, they can use modeling and they use other published values and the literature is a lot of, well, there's not that many techniques but there's a few techniques that have been used to refine that attenuation factor. So the the answer to your question is really the NEPM does use old conservative attenuation factors for chlorinated substance and that's a that's as far as I'm concerned a fact. And the reason for that is there's many reasons for that but one of them is because those values in the NEPM are meant to apply to just about any situation. Right. And I think in the game this is an opinion of my end that there would be some scope to create. You could easily create an HSL for a building that has a basement or of a or of a sand. You could do one for one that has no basement. You could do what you could. You absolutely could. Right. It would be possible to do that. Perhaps at the time of the drafting of the NEPM they wanted to stay within the four HILs categories and just leave it at that. And I think I can understand that decision. The reality is it would be possible to create more standard situations or standard building structures and create guideline values that are protective of those. That are perhaps less conservative. All right. Well, thanks for that answer. We're going to move to the early bird questions. For those of you who don't know the early bird questions are those that come in before we start the talk. I'll move to those now. So is our contaminated land industry a first world problem? Are we cleaning up sites that pose no acceptable risk? This question actually, because it's actually a fascinating one. One of the most of the EPA I was asked the question maybe every day. Again, you're asking for an opinion here. So opinion is what you're going to get. I think that first of all, it is a fact. Yes, that the risk profile or the risk appetite around a hazard changes based on the jurisdiction, based on the community expectations, based on literally the country you're in. Right. And I can tell you this for fact, because in the United States, for example, the acceptable cancer is changes by a factor of either 100 or 1000 between states. So in Hawaii, they'll accept one in a thousand, I think, and then in California, they accept one in a million. I think those numbers are right, but please don't quote me on those exact numbers. So that tells you something about how the risk appetite is a function of where you are. And in Australia, we have a certain risk appetite that you may agree or disagree with, but it does exist. And it has been applied broadly and relatively evenly across the country. I'll also note that the risk appetite isn't always exactly the same even between environmental disciplines. So for example, the risk appetite in air pollution and the risk appetite in soil and contaminated land might not be the same. So and I'll give you, there is an obvious example, anyone who looks at the the NEPM guidelines for air. And I'm talking about, for example, the particulate ones and the ones for sulfur dioxide and nitrogen dioxide. Those are not based on creating no impact. Those are based on a certain number of people being impacted, right, which is quite different. It's actually based on an economic assessment of how many people can get sick. And it's all written in there. You can see it very, very clearly. Well, contaminated land is run on the principle of negligible impact, which basically means that it's approximate zero. Right. And again, that's, there's a lot of people who disagree with that. I totally understand what they mean. Personally, I think that our risk framework is fair. It is in line with international standards. It is. So it's not some crazy Australian invention. It is something that has been applied in just about every western country. And, and it is applied quite consistently. I would say that as well. So, and I would also add one thing. There is a difference between contaminated land impacts and risks and the ones posed by some other environmental media. And this is something that I, I know people often don't think about contaminated land is there for a very long time. Hundreds of years, maybe even thousands sometimes or some forever. Right. Well, you know, for the foreseeable future, that's what I mean by forever. So it makes sense for an extra level of conservativeness to apply. If you've got a puff of smoke in a few minutes, it's going to go away. If you've got a contaminated site in 100 years, it's still going to be there. And who knows what it's going to get used for. Right. So we do our best to assess, of course, for the next intended use of land. But it makes sense to me to have an additional level of conservativeness in there to account to some extent for the fact that land, crazy things happen with land. It gets redeveloped, it gets moved, all sorts of things happen. So there you go. That's my opinion on that. Right, Victor. Well, that's a very long opinion. I'm sorry. And I have to have to stay short and punchy with your opinions. I will do that next time. I promise. Question number two, how far should the residential buildings be from a landfill? Oh, well, that one's not really for me. It was not what this research looked into. Every state has its own guidelines, right? So the buffer distances are defined from state to state. So I would not dare to set foot on that particular topic, partially because it's not really what this research was on. So that's saying look up the guidelines. Question number three, what are the most urgent needs in this space and who is best placed to address them? Right. So I think I honestly believe researchers, there is some work that needs to be done on better understanding certain, not very sexy pollutants. That's one thing I believe that needs to be done. A second one is I think the reality is policymakers do have the finger on the pulse. And I say just keep on doing that. Keep having your finger on the pulse. And perhaps whenever there is a need to update or review the various screening levels, the screening values, of course, this research shows how important it is for the screening values to remain current, to remain up to date. It creates so much work and so much, it creates so much trouble in so many ways to not have robust screen, in current screening values. And to an extent it also talks to planners. I don't know how many planners are in the room, but this really, it tried to show you, you know, when you're looking at redevelopment of historical land. I hope what I presented to that really shows that, you know, historical uses of land do create a risk. And it's not just an academic exercise. It's not box-ticking. Not that I thought you thought that. But, you know, it is something very important to look at. And this research shows what are some of the land uses to really keep your eye on. Question number four. I'm interested in implications of this research for planning systems reform. Well, that's, I think I've answered it as much as I can already within the previous one. Okay. Number five. Are you seeing more biochar used in land remediation? Well, I mean, it doesn't have much to do with what I did. But I'll answer it anyway. I've never seen biochar used in land remediation. There you go. But this is just me. If you're asking me for what I've seen, I've never seen it. Which is not in any way saying whether it works or not as good or it's bad. It's just a lucky draw I happen to have never seen it. Alright. Question six. Benzoa Pyrene use CRC, NEP and Canadian SQG. Also is BAP TQ2 sensitive and estimation for tier one criteria? Now, so, okay, we'll go into this into too much detail. But one thing I'll say is that, you know, there is the well-known issues around the Benzoa Pyrene value for ecosystems, which is not what we're talking about today. Today we're looking at risks to human health, not the ecosystem ones, right? So I know that there was debate in the industry and there was, you know, industry associations discussed the length of the various potential values that could have been used for the Benzoa Pyrene ecological value. I didn't. So yes, for tier one, for human health, I don't think it is too conservative. This is just my view on it. I think it is an appropriate value. And basically, Benzoa Pyrene really lends itself to risk assessment. The screening levels have to assume that the exposure is continuous over however many years, right? They have to. They have to assume that. And it is up to the risk assessor to say, hang on. No, this kid will only go to the school for at most six years. Therefore, the risk would be lower, right? When you're assessing a school, but the NEPM could never take that into account. That's just not possible for the NEPM to do, right? So I just thought I'd give you that example as a perhaps a silly one, but it's something that's, so I think it is appropriate. One for me is LDPE versus HDPE tubing for collection of samples analysed for PFAS. HDPE is typically considered better. And there is some US EPA guidance on that if you're wanting a reference for why to justify the extra expensive HDPE. Question number eight. What are the health risks associated with sanitary landfills that utilise CAT-C soil for daily cover? All right. So CAT-C soil. So this is a Victorian term really. So for others in the room, CAT-C soil is soil that includes a degree of contamination, right? It is not at the very high end. It is not at the clean end. It is somewhere sort of in between. So, I mean, of course the risk change is completely, but this is true of all exposure risk. There's always true based on the distance to the nearby receptors, based on the use of the land, based on, you know, find its use for the cap, how long is it going to be before the cap actually gets remediated and closed down? Of course it is related to how much pollution is present in the CAT-C soil as CAT-C is arranged. So, you know, I would never be able to tell you just like this off the top of my head, CAT-C soil for capping material is fine or not fine, right? Because it's not as simple as that, right? CAT-C soil contains a degree of pollution. That's the definition of category C soil. How can that pollution leave the landfill, right? It can leave through leaching. It can leave through wind-blown dust. How much will really be carried in that wind-blown dust? Is it a reasonable amount? Those are the sort of things. So I'm sorry. I know it seems like I'm dodging the question, but the reality is, you know, this is always true. Just having a scenario, risks never exist on their own. This is an absolute truth in our field. The thing on its own, a cigarette doesn't create a risk unless someone smokes it. All right. So it's just, that's just the way it works. So I just thought I'd elaborate on that just because this will be true of a lot of scenarios in a lot of people's heads. All right. This one I know is one of your favourites. Number nine, hemp cleanup and agri-growth industry or hemp to hydrogen. I have to be honest. I did not understand. It's not related to what I did. So obviously I know absolutely nothing about it. And I actually would love that to be honest. I read it and I was like, I want to know more about this. But unfortunately, this is not what this work was on or anything I've ever worked on. Once I looked into the use of hemp for fighter remediation, and that was fascinating, but... Well, maybe that's the emphasis of the question. Yeah. Well, we couldn't use it at the university because there was a concern that students would break into the glass houses and steal it. Right. This is, I'm not even joking. That was the concern at the time. So I was not allowed to do that reason. That's holding up good research there by the sense of it. All right. So perhaps the person who posted that question could send us a few more details in the Q&A. All right. We're now moving to the Q&A section. So thanks for all those early bird questions. All right. So Ron Blankenforth. What about PFAS? Okay. I think you've answered that one already. And pesticides. I know. Pesticides. Isn't it fascinating? Not a blip on the radar. I thought fascinating. Thank you. Whoever asked that, I don't know if Ron, if it's still you. A brilliant question and very good. I like when people can spot the gap. I thought it was a fascinating finding in itself. So much research on the toxicity of pesticides. So much work on deriving all these criteria of pesticides. And no one ever finds them anywhere. That's basically what it's finding. And they certainly do not get, or they certainly, they almost never get found at levels that exceed the guideline values, the screening guideline values. The screening guideline values for pesticides are really quite robust. I would say, again, in my judgment, I would say they're very, very strong values. And it is fascinating to me that, look, even when I worked in Contam land, I think I might have had one detective, one pesticide once. It's rare. Finding them is rare and finding them at levels that exceed levels that are safe for human beings is very, very rare. Could I say, and I do want to say this, because this is outside of the research, but I think it's important, is really, let's maintain the focus. So for today, let's not forget that the work that I did was on risk to human health. Pesticides, when you look at them, it's primarily an ecological risk, which the work I did couldn't look at. It was just not possible. It would have blown out proportions. It was hard enough as it was. But so I know for a fact that pesticides are present in rural waterways and they're often present. This data is freely available, are present at levels that may well be poising and impact to the ecosystem. So let's not mix those two things. Humans are much more resistant to pesticides than the receiving environment. And that's not a coincidence. Pesticides were designed to be toxic to certain insects and they were designed to not be toxic to humans. So it's not surprising, right? Or not be as toxic to humans. All right. That is an interesting observation. Did you distinguish between 53V and 53X audits when assessing the results? No, I did not, right? The reason was for anyone in the room, who is not from Victoria, those two different audits, the X audits or the 53X are the contaminated land audits that in Victoria used to be done, it's the premise change now. They used to be done specifically for an assessment of the contaminated land. It's not quite the right legal description, but you know what I mean. And the 53Vs were more facilities audits, right? That often just included an element of contaminated land, but they often were about lots of other things and they were often specifically for landfills rather than for contaminated land. So no, I did not separate between the two because ultimately there were not that many 53Vs that included a health risk assessment related to contaminated land specifically. So it would have been a handful. And when they were done, as far as I was concerned, they were just a content land risk assessment. At the end of the day, it's soil, it's water, it's vapour, there is a receptor. So that was the way it worked. So no, I did not tease them out specifically. All right. And now Ron, who asked the question about pesticides, is extrapolating to say in agriculture, EG oversprays and found on foods and water. So I think you've answered that question. Really? Yes. I will say one thing though. When it comes to food, and I hope everyone here, maybe people don't know this, but food is regulated in a very specific way. And auditors walk a very fine line when it comes to food. They do not look at the buildup of pesticides in food grown on a site, grown on a commercial site. They will look at veggies you've grown in your backyard. And there is a fine line there. And the jurisdictional boundary is quite strong. And it's a very important one to separate. I won't go into it now because it is, and I would get it wrong, to be honest with you. But it is quite a complex division between the pesticides that you'd find in your backyard and you grow with your veggie patch and how those are regulated, which is normally by the environmental regulator locally, or the food that you buy in your supermarkets, which is normally regulated by health departments. So it's actually done in quite a different framework. So at risk of getting slightly off track, the wastewater reuse and the criteria that is set for treatment of that prior to irrigation, do you think that poses more of a risk than, say, contaminate land? Oh, God. Let me think. I wish I could tell you that I know the ins and outs of the water reuse guideline. That's my problem. Because I know, what I do know is that I've failed to affect a lot of assessments went into the right values that would be protected. And that I was quite comfortable with that statement. Us to comparing these two things. Oh, God. Is there a difference between those two things? Because contaminated land is this broad framework of assessment. Well, I feel like it's a lot bigger. So I don't think it's quite an apples for apples comparison if I may. But no, I would not be able to pick a favourite between those two if you will. No, I wouldn't be able to do that. No worries, Victor. I wouldn't have either. There's a question relating to your presentation slide. Should not the frequency be one to 5% instead of not to 5% in the table of chemicals of potential concern? Oh. Okay. I love it. It should be greater than not to 5%. That's what it actually should be, right? Because technically it could be 0.000007 or one. That is correct. So you are right. It's misleading, but one to five would not have worked because what about 0.5% So there you go. But yes, this made it into the paper. Let's hope no one else. But my goodness, I'm impressed with that comment though. Whoever pointed that out. Good attention to detail. Gold star to Margaret. 100%. All right. Next question from Ruth Davies. Hi, Victor. My team in Environment Protection Branch of DWECA is currently working on planning policy reform related to contaminated land. I'd love to have an offline chat with you about how we could use your research. Well, there you go. Well, I'd love to. And of course I know Ruth Wells from years of working together. So nice to see her, Ruth. And yes, more than happy to chat. And my paper is available online for you to charge. I know I've said it before, but just in case it is there. All right. Next one from an anonymous attendee. Service stations are very ubiquitous and also quite strictly regulated. So lucky to have more audits associated. Would this have an impact or skew the data? Absolutely. The answer is absolutely. Yes. Remember when I said this is not a clean data set. That is exactly what I meant. And anonymous person. It's a very good person. Very good person. Very good point that you raise. And I'll give you an example of another one that is the other way around, which is, did you notice how little mining was in there? And there is, oh, there's not that much. And the reason was because mining normally, mine sites are not restored into house, into summits. Right. You don't build a suburb on an old mine. Right. Normally gets restored to a natural ecosystem or some kind of mine rehabilitation. So can you see how that's another example of an equal and opposite effect of something that is actually perhaps under represented in here. And because, because it just you almost is very rare to do an audit of an old mine site. Very rare. Pretty rare. Because normally it doesn't get redeveloped for residential use. So yes, you're absolutely right. And so this data is skewed in many ways. Right. Let me be clear about this. There's a lot of ways in which it's skewed, which is why you may have noticed. I never said that this is definitely that. Right. It's, but what this does, this data, I think the, what makes this data interesting is that it's skewed by a million factors that are all real. Right. And they're all happening right now. So it actually tells us a lot about what our machine, the Contam land machine that exists in Victoria, what it spits out. Right. And for example, the overrepresentation of service patients is totally part of it. Right. Because no one will ever forget to do an audit. The council person who decides that whether the redevelopment of a service station requires an audit or not, they will never get that wrong. But with some of the other land uses, perhaps, you know, we've all seen it times where perhaps something should have been audited and maybe it wasn't. Right. But we know service stations front of mind always gets audited. That's absolutely right. All right. Next question is from Greg. Nailed. Was there an analysis on the medium that triggered the health, human health risk assessment, therefore vapor versus soil versus groundwater. So Neil, the answer is no, and I absolutely wanted to do it desperately. The reason it couldn't be done was because the risk assessments, some of them report separately the risk for each medium, but others don't. Right. And so it would have been a nightmare for 370 old risk assessments to try and dissect it. And the reason I know this is because initially I tried. Right. And I got the second assessment I gave up and I said, no, that's it. We're just looking at the overall one. However, I think there is one thing that is significant and worth noting, which is if you look at the table of pollutants, right, and the ones that get assessed more often, you will see that there is a strong, and I wanted to say this and I forgot to say, there is a strong over representation of the top rows of volatile substances. And that is not a coincidence. Right. That is because they are the ones for which vapor intrusion and inhalation is the exposure pathway. Right. So the reality is even without having explicitly done the assessment of splitting the risk factors individually for medium, which frankly would have been fascinating. Right. Anyway, but I would still be doing it now. So, you know, it's still implicitly it is possible to infer that vapor intrusion is by far, by far the strongest, though the most frequent in terms of the one triggering the need for a risk assessment and causing the selection of a pollutant to be required as part of that risk assessment. And just I'll tell you again, because you don't have that fight in front of you, you know, in your top 10, 20, you know, whatever it is in those top categories, you know, you've got benzene, naphthalene, ethyl benzene, toluene, xylins, all the dichloroethanes, you've got the PC vinyl chloride. Right. It cannot be a coincidence that it is always this highly volatile substances. The only non volatile in the top three categories was benzoypyrin. In the top two categories was benzoypyrin. And why is that? For all the reasons we talked about earlier. But they're not really overrepresented. It's just a practical consideration. They just happen a lot. They get assessed a lot. That's what it is. They get assessed a lot. And what does that tell you? That tells you that someone more often thought that they posed enough of a concern to warrant the risk assessment. Victor, I'm just wondering, like, you know how we have these groups of analytes in certain, you know, from the lab, like it used to be a US EPA screen. I'm sure what it's called these days. I mean, effectively that's becoming a quasi list of what we think of as priority contaminants because the consultant only has so much to choose from. And they will choose that. Is that not skewing a whole lot of this as well? Absolutely. And I'll give you, look, the ultimate example of that for me is dioxins, right? That's just for me is because, you know, you would only ever analyze for dioxins in soil or water. It doesn't really matter. If you were really damn sure that there was a source of dioxins on the site. The reason being, so let me let me paint a picture for anyone in the room who perhaps is not that familiar with this. So dioxins, at least in the past, and I'm sure it's still true now, very expensive to analyze, right? It used to be $800 or $1,000 a pop, $800 if you sent them to Germany, right? It used to be a big deal, right? Maybe it's still the case now. I don't know. So that's, it's an expensive analysis for one sample, right? For pollutants, that's everywhere, right? Because dioxins are literally everywhere because they're atmospheric. They occur through atmospheric deposition, right? So you will always find something and they're analyzed to nanogram or pachogram levels. So you will always get the text, almost always get the text. For a pollutant that doesn't have a screening level. So you've got the trifecta here of something that is ridiculously expensive to analyze that, that occurs absolutely everywhere and that you don't have a screening level for, right? So basically, if I were to just be an eager beaver and go out of the dioxin sample, automatically I've created this whole piece of work where I have to do a risk assessment because there is no guideline value because, you know, I've done there automatically just because I collected the sample. And that is regardless of the risk it poses. As toxic as dioxins are, which they are, the reality is they are absolutely everywhere in very, very small amounts. So the principle of dose response applies to them like it applies to everything else. You still need to be exposed to enough to actually trigger an effect. So that tells you something about biases, analytical biases that occurred because of the pragmatic considerations that the consultant would have in that moment. So Richard, I know it's a little bit different from what you said, but it's an example of how, yes, you know, we'll get a suite that has a pollutant in there or doesn't. You know, when we do our phthalate suite, which we'll do once in three years, if you are a good consultant, we'll still, you know, it's very, very rare. You only analyze for those phthalates that are quite common, right? So all of this is, you know, these are, you know, I've just thought it's worth pointing out, right, that these are analysis that basically the pragmatics of the analysis do drive the outcome to some extent. We'd better go back to these questions. Otherwise, David and Thomas will get upset. So David Beceto, how can we determine the contamination of water or waterways or stream and rivers from arsenic and other chemicals from a gold mining tailings dump? How long will it take the river to recover or rehabilitate? Wow, that is a fantastic question, a very important one. It's an important question. So, and of course, and I'm sorry to do this too, but you know I will not be able to give the answer to something like this. I wish, I wish it would be possible to just, right? So the reality is, I know a couple of things on that front that, you know, from my days at EPA, I know that the EPA has popped in Victoria, but I know in various states, the regulators have published data on heavy metal concentrations in streams as a result of mining activities. So I would recommend that you have, I don't know what state you're in, but I would recommend that you go and look at the local environment regulators website, depending on where you are. They may or may not have done it. Academics have done a ton of this work, right? Academics love taking samples of water near mine sites. I'm joking, but like it happens relatively often. There's lots of studies on that. So, you know, so that's another place where that information can be found. In terms of literally collecting a sample, I mean, there's a lot of methods and, you know, I would not go into the details of how one collects a water sample from a river. But, you know, obviously consultants have certain methods that they use that are extremely rigorous because that's what they have to do. But, you know, the reality is there is methods out there and it's not really that hard if you want to collect just quite a simple sample that can be done. And in terms of how long does it take a river to clean itself, that is an impossible question to answer as a general one because that changes from river to river, right? You are a tropical environment that gets the monsoons, the river gets flushed out every year. If you are in a drier environment, you know, it changes completely, right? So the reality, and of course, is it a little creek? Is it an ephemeral creek that only runs for a few weeks a year? Is it the Murray, right? You know what I mean? Completely different situations. So the reality is rivers do flush themselves out over a period of time that absolutely is the case and that absolutely does happen. And do they flush themselves out perfectly? It takes a while and it can take, depending on the type of pollution it can take a long while. But it's something, so you understand, I just thought I won't be able to give you the answer in terms of how many years, but I thought what I'd do is just tell you what are the factors that decide how long it might take. So I'm sorry, I know the answer is not quite an answer, but at least it's partially there. Yeah, they're good. Go right up. Next question's from Thomas Lancaster. Do you think with the possibility of establishing guidelines for microplastics and other emerging contaminants, there is likely to be a sharp increase in the number of human health risk assessments conducted for these, that COPCS. COPCS. In the next decade, can we utilise the data you have presented to help inform future regulation for these emerging contaminants? That's a good question. It's an excellent question, Thomas. So, we can talk about it for an hour over a glass of cognac, but the reality is, so, the answer is yes, having a greater awareness of more pollutants will create more risk assessments, and I think that's a fact. And actually it's a demonstrable effect because any risk assessor in the room would tell me that they've done a ton of risk assessments on PFAS since the emergence of PFAS after the piece of work that I did. So as other pollutants emerge, we could expect a similar pattern to occur, right? So I've spoken to so many risk assessors out there, and now basically all they do is PFAS, right? So, I'm exaggerating. Sorry, please. I just realised I should be careful not to embellish too much. But of course that would happen as other pollutants emerge in our awareness, regardless of whether there is a guideline or not. As they emerge in our awareness, then, of course, there would be a greater awareness that the analysis exists. So, responding to what Richard said earlier, there is more analysis available. We analyse for it more, we find it more. There is greater awareness, I think, to look for it more. So I will assess it more often. They're also, and I think it's worth noting, and people complain about it, but it's natural and normal. When it comes to emerging contaminants, screening criteria that are developed for emerging contaminants, that's what you were talking about, when they develop guideline values, at the start, they are always very conservative because at the start, there is always very little research. So, by definition, whenever there is greater uncertainty, you have to be more conservative. That's an absolute truth in the environmental sciences. And so, as emerging contaminants come up, when they will come up with a guideline value for triclosan or for some of the phthalates and things like this, which I suspect is going to happen, it makes sense to me that they are going to derive guidelines that are quite conservative because, by definition, emerging contaminants are not as well understood. And so, what does that mean? More conservative guidelines mean more risk assessments. So there you go. See, I hope you can understand the pattern there. Last question from me, and thanks very much for all those Q&A questions. That was excellent. Do you think we're kidding ourselves, just in terms of looking at, say, compound-specific risk assessments and really not even trying to look at, say, the additive effects of multiple compounds at the same time and trying to work out the impacts on human health. Are we not better to go with some broader, cumbersome indicator and just say, well, that's it because there's so many emerging contaminants that I can't imagine they're going to keep up. And there's so many permutations and combinations of additive effects. Are we not better off to come up with a different way of... Sorry, indicators. I mean, there's entire conferences on just this topic. So we'll keep it short. And I would ask you to have a chat to anyone in air quality about this. You want to talk about pollution mixtures, speak to an air quality expert, and you will see them weep. Because that's when you truly, truly, truly get mixtures. Of course you get mixtures in quantum land, the water, of course you do. But the reality is, in this context of quantum land, it is common that there is one or two or three or five key pollutants on a site that are the ones that are driving the majority of the risk. Is this absolutely always true? No, absolutely not, but it is often true. So I would say, so the framework we have actually often works quite well from that perspective. So as a starting point, it already has that. Second, you know, many attempts are being made in the scientific literature right now to try and come up with assessments for chemical mixtures. And, you know, the reality is, at the moment, there is no system that is better than the one we have right now. You know, and in one we have right now is very conservative, because what it does is add a, or adequately conservative, depending on how you want to look at it. Because the system we have now basically says, pick the pollutants that are the key ones. Don't just pick everything, pick the key ones, assess the risk from them, and in the risk assessment you add them to each other. You assume that each of them just has an additive effect. It is quite rare for pollutants to have synergistic effects, where the sum is greater than each individually combined, right? So that's really quite rare. So it is considered to be adequately conservative, and also it is just the risk framework we have right now. Sometimes you just got to work with the framework you have. I, while I will not share the, Richard, if you don't mind me saying, slightly defeatist tone of your questions, I might not share that, but I do share that there is a need for more work on, the reality is chemical mixtures are the future, right? That's just the way our industry is going to go. So, and that's a fact I know this, because you look at what's happening in Europe and the US and they're already moving in that direction, looking at more of chemical mixtures and that sort of thing. So it is what's going to happen. Our industry is absolutely going to change and have more of it. So basically the researchers got to be researching the policy makers got to keep their finger on that pulse, because once the research reaches its critical, not critical mass, it reaches that burden of evidence that is adequate to have a new method that gets used, then it's up to the policy makers to make sure that it gets implemented in the industry. Thanks very much, Victor. So we're well over time and really appreciate your extra time and many things to everyone who's stayed on. It's fantastic to see so many. So just really big thanks to Victor Kobay for his great presentation. Thank you very much, everyone. It was an absolute pleasure being here. And can I just say, wonderful questions. I really enjoyed them. So thank you very much. Thanks, Victor.