Liquid material being dispensed into test tube with dropper
Implications of Low-Level PFAS Treatment Goals

Webinar date: January 26, 2023

Learn more about PFAS regulatory updates, the rationale for sub-ppt Health Advisory Levels, and the connection between low ppt remediation and greenhouse gas emissions. 

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This transcript was auto-generated by the webinar. Please forgive typos.


Hello, my name is Amy Blyth and I am with Trihydro Corporation. Welcome to the webinar. Today, we'll be discussing what's happening in terms of the latest developments in the ... world. We will cover implications of low level treatment goals for PFAS, How to handle Regulatory requirements and Minding Environmental Footprint of Remediation. Before we get started today, I would like to go over a few housekeeping items. This Webinar will be recorded and will be available after the webinar. We will send an e-mail out to all of you with the recording, as well as a copy of the PowerPoint. All attendees are in listen only mode. If you have questions for our speakers throughout the webinar please put them in your questions panel in the GoToWebinar tab as you see here on your screen.

Finally, you'll have an opportunity to complete a short survey at the end of the webinar. Please take a few minutes to do. so as this information helps us plan our future webinars as well as give us feedback on this one. Please place your topics about what you'd like to hear in the future from Trihydro with regards to webinars in the questions panel.


Alright, so I'd like to get started by introducing our speakers. First off, we have Mitch Olson, and he is a professional engineer with a PHD in Environmental Engineering from Colorado State University. Doctor Olson is Trihydro's Emerging Contaminants Director, and he has 22 years of professional experience including industry and academia.

He has been providing technical guidance to Trihydro's ... projects. Over the eight years, he has been with the company, Dr. Olson has been a member of the PFAS Team, since its inception five years ago, and has contributed to the team, as an author, and a trainer. He has also contributed to guidance stock documents with by the National Groundwater Association. Today, Mitch will be covering analytical methods and detection limit, unintended consequences, the connection between the low PPT remediation and greenhouse gas emissions.

Next, I'd like to introduce Andrew Pawlisz. He will take on the second part or, excuse me, held start us out today. Andrew is a board certified regulatory toxicologists with a Trihydro Corporation in Tulsa, Oklahoma.


His role involves keeping tabs on environmental, chemical regularly, regulations impacting industry, and other regulated entities, inclusive of tracking rulemaking activities for contaminants of emerging regulatory concerns, such as PFAS. He began his PFAS journey over 20 years ago, assessing bile accumulation, Potential, exposure and Toxicity, Toxicity of PFOS, and PFOA. As part of environmental assessments by USEPA and Environment Canada. Today, Andrew will be taking on the topics of regulatory updates, both state and rank, or, excuse me, and federal evaluation on the rationale for subpart ppt, and the USEPA Health Advisory Levels, so, I'm going to turn it over to match to introduce asked, run over the agenda, and then he will take it from there, OK, Mitch, Thank you, Amy.


OK, next slide, that's good for our topics today, Amy alluded to this in the introductions previously, but we have four key ideas that are all part of the running theme of the implications of breaking this PPT barrier and the kind of race to zero that's underway in terms of regulatory levels with beef as the four key primary topics here.

As Amy mentioned, first, to, Andrew will be covering regulatory updates and evaluation of rationale for sub part per trillion levels. As if some of you may have been a part of our webinar, about a year ago, November of 2021, that was where we had a Webinar on Regulatory Updates and ... being what they are: ever-evolving regulations that are underway.


And so, more, more regulatory updates. Webinars may be anticipated as things continue to evolve, but I will get the latest and greatest in that area. So, Parts 3 and 4, then I'll step in on analytical methods, detection limits, and the unintended consequences, and looking into some of the other impacts that may occur when we get very low in our treatment goals with PFAS. Next slide. Before getting into those, that have just a single side here as a PFAS background, and really, just to provide a high level.


We really don't tend to, this to be a one-on-one level webinar, and provide detailed background information on this, but just enough to establish some context for where we're going, and a little bit of info to set some terms that we'll be using through this presentation. So, very briefly, the ... background, as all of you on this call are probably aware, at this point, it's this acronym for this pretty horrible term, per and Poly fluoro alkyl substances. The complex chemistry is one of the many complicating factors of ... is an estimated 10000 plus compounds that have been identified. A lot of environmental releases might have hundreds to thousands of individual compounds that might be identified PFAS, so ubiquitous in society. A big component. one of the many elements of the challenges of managing ... is just how widespread the presences.


And we'll talk a bit about that today in this webinar in terms of how that ties into the challenges of regulations And analyzes and such an emerging contaminants, of course, PFAS, an emerging contaminant really, the poster child of Emerging contaminants, I think they call them the defining emerging contaminants of our generation. A lot of challenges around ..., not the least of which is the fact that they are so very stable and difficult to remediate both due to their transport properties and the extreme relatively extreme stability and also being subject to increased regulation. And that's something that Andrew ... addressed today as part of the webinar, and that's ever-changing area, too, in terms of the level of ... regulation.


So, the two topics I'll cover our cover in context of sharing with this audience, the latest and greatest in terms of the regulatory status, but also looking. So, to speak under the hood one why some of the federal regulations, especially health advisories are so low. So, I'll go quick, and I believe you will get a copy of the slides. And, also, this presentation is recorded, so you can refer to these at your leisure. So, this graphic is really a snapshot of what's going on right now with be fast at the federal level. So, the way to interpret this, our boss graphic is that the rule, citations on the bottom, regulator, they already have explicitly included PFAS within them. You can refer to the legend or the acronyms, and then the sand, also the speed above it is other about to undergo that little making status change, or it's currently in it squarely. So as we speak today, there are four major environmental regulations that are moving quite quickly, in terms of PFAS.


So these are, the circle, is super fun, Clean Water Act, Safe Drinking Water Act, And. So next slide, please. So next, few slides will essentially give you a snapshot of each of those candidate top contenders. So, in terms of the stark law, I think the issue at hand is the official designation of PFAS, specifically to combine with an MP four and be false. That's a hazardous substance. And we see this event as a trigger, not only changing the aspect of the Superfund rule by itself, but also causing domino effect on other environmental rules. In terms of the timing.


I think we are now looking at 2023 and beyond that, but really to have not been recent analysis for EPA on anything that was more recent than proposing the proposal that was issued last year. And then in terms of communications, once these two compounds are officially designated as hazardous substances, there will be mechanism for cost recovery in terms of paying for the keno elimination, otherwise pollution. And also another application to keep in mind is that in addition to these naming these two compounds as hazardous, I believe there's additional intent by agency to look at potential designation additional compounds. The next one is the Safe Drinking Water Act.


Essentially this is the rule that regulates drinking water from use and the key event is the draft establishment and follow-up promulgation of the MCL. And along with it MCF G I have another slide subsequent to this: explain the difference. For those of you who know now again we're looking up initially to P plus compounds, and the N won't Envision endpoint recording to EPA's schedule and rulemaking requirements. It's towards the 2024. But again, I think there's a little bit of a delay in the envisioned sequence of events as outlined in the PFAS strategic map, or Action Plan. So, in terms of education, clearly, once we have MCL MCO just established, that would be required for monitoring, treatment, and otherwise compliance requirements.


So, it's quite significant development that piece two compounds are undergoing right now, Next slide, please. As I mentioned before, there's a little bit more detailed slide. On the right hand side, you see the progression of the various rulemaking steps for MCS NCO chase. Also want to make a note that EPA has made a determination to proceed with MCL, ... as well as this continued commitment to monitor fiscal these contaminants. While the NCI ... is being developed, the latest one is being implemented.


This year they use EMR. Also just to keep in mind that MCL isn't forceful. Invasive considerations of health impacts costs. Analytical and treatment options have limitations, whereas MCL G the guideline it's not necessarily a plausible and just looks closely at it. The scientific merit of the amendments, also, inserted, is the current numbering or number system for people. So, before health advisory level is also listed in the US, it will be a BS and Gen X, But looking at those numbers, although that's interim. They're quite low, and, hence, the title.


After today's webinar, and mentioned, we'll cover some of the challenges associated with setting up as well, limits, And also, if you read closely EPA's documentation guidelines, then release those. It would seem that, at least now, they intend to take those as binary levels and move forward with. But, again, we don't know what the outcome will be subject to reviews and other feedback mechanisms to influence those numbers backslide. And then I believe this might be a final summary slide for those top four contenders in the current rulemaking process. This is the Clean Water Act, specifically looking up the ward quality criteria.


The draft called Criteria for Aquatic Life has been released and then also awaiting the same type of limit for human health that's coming more in terms of 2004 and cares of the impacts implications. There's two sets of effluent guidelines or even pretreatment is technologically based and mentioned later, but also there's the water quality based criteria. And both actually play into the permitting process. There are delegated the states or under EPA's prove here. There's few states could do that. But, nevertheless, there will be treatment and treatment monitoring, even on quarterly basis of the levels of, certainly, ... compounds. So definitely significant compliance implications for all the industrial and silicates. Next slide, please.


All right, So, to round off the parallel auctions, quick summary of something to keep track of. A watchlist, if you prefer to look it that way, but this year and next year, and I think they are the items listed in yellow. I would recommend that focal o'clock, the closest, and definitely, there's a lot of activity in terms of the casco, Toxic Substances Control Act. There is that proposed rule for retroactive reporting of ... compounds. Currently is in the draft stage, although there's some issue with the cost analysis that may actually derail the process a little, but nevertheless, I think the EPA will proceed with the rulemaking process in concert with EPA seeking information on the reverse effect of PFASTo have this issue test orders under TSCA.


The TRI reporting, also quite a few changes there, designated PFAS special star and that has the impact of potentially remove any de minimis exemption for any quantity. Currently, it says 100 kilograms or pounds per cameco per year. And also, I also mentioned the waterfall criteria there, and, permitting developments. And then, this is something mentioned we'll talk about, is that there's continuous advancement by EPA in developing lead testing methods  And then, looking forward, as I mentioned before, next year expected the award of criteria of Human Health.

Also, maybe issuance of the technologically based, something also that EPA is looking at now in terms of risk evaluation, The impact of biosolids. Specifically, the application to, to land and other uses, OK. So, I will leave you with this slide. But, I think the general impression that's out there is that the extent and the bigger the application of the Federal rules and regulations, PFAS is sound precedented to compare to any other environmental contaminants that I had a chance to work with. Next slide.


And this is just kicking up to the state activities. Given the limitation of time we have today, I did not go into much detail in terms of quick snapshot, looking out which states have issued some type of guidance or information to the public. And, those states are marked in a darker blue, or green, and those who do not have such guidance and information to public, is the light shaded gray. And what's interesting about this overall picture, but also the fact, based on the research or server from iOS, there's certain reasons given by the states did not proceed with the PFAS guidance documentation.


And there's three reasons. one of them is doubt. They are prohibited, setting standards lower in APIs. The second one is a lack, and pressurization, of those resources. And, then, the last one is citation is that there's still uncertainties in the toxicological analytical methods, treatments and such. So, these are the main three reasons, and I suppose, once more, information is provided. This is a quick summary, top three, lessons learned, from the presentation, on Part one, there's no doubt, there is heightened pace of multimedia regulatory activities, and that's the close. ...


states, those are those states that proceed on that pathway. And as you saw the insert, at least from the health advisory, there is a decreasing trend. And the limits imposed and water waste, and even consumer products at the state level. And then, speaking specifically, to the state agencies, in general, they mirror EPA's actions, but some may wait, but others have events beyond what EPA has issue in terms of guidance and regulations and even establishing stricter controls.

What makes those low PFAS levels go?

So here it is, before I look at showing you some of the numbers that it was using to derive the health advisory and some of their bonds, let's just review what the agency is saying about the environmental health effects. So they're all listed here. I'm not gonna repeat them.


But, obviously, agencies have concerns, and one thing I want to mention is that, on the third major bullet in red, really did focus on human subjects paths, rather than something that we see in laboratory. Simply because human receptors are closer, two are the actual effects that people may have even though there is still some uncertainty from the cause and effect, exposure, conversion. Now also interesting in this slide, the model and I'll look at it later, they are blood screening levels issue. Their clinical application is debatable although it is nice to have those limits, that's the risk assessor or permission position, but again, I caution against using those blood level screening levels to draw any solid conclusions.


Also interesting to note is that while the pair organizations mostly focused on two people species, these log screening levels are ....So a little more advanced, just strict exposure to media regulations. Next slide. OK, so, Arithmetic, behind the health advisor developed, and it's quite simple, you have three main mathematical input parameters, one is the toxicology of data. The RMS exposure metric one, which is drinking water intake, and then what I call explosion metric too.


Broadly access to distribution in which really upsets the percentage of the input of PFAS, uh, from water versus other sources, such as food and other sources. So, it's quite simplistic, although the science going into each of these is quite complex. Next slide. Real quick look at what EPA was looking in terms of the available data for these two compounds. You can see that they consider not only human subjects, but also animal. That's why those models. And that's quite intriguing. And then also, interests are the effect categories.


These are the actual adverse effects, which could be serious endpoints. Alright, and we thought I'd show you those input parameters. I just want to maybe take NaN to review the general model, and this is the general model that I guess conceptualizes the succession events that needs to take place between exposure or contact. There is one here in the very general terms, all the way to the pathological outcome that is visible, offset disease, or otherwise some type of harm seen in the population. And, I think the key message of this summary slide is that the Interim Health Advisory Office operating within stage two.


Within that physiological adaptation of organisms that may be exposed to various chemicals. So, yes, we are looking up arch evasion of biological mechanisms. Yet, it is uncertain, if those Part two basis and changes actually express themselves in the actual disease, It may need some type of health protection action. So, just keep that in mind.


This will explain, why self the lives of a startup. So, here's quick table of the input parameters in cows in terms of the first metric, that toxicity reference dose, that the health advisors I used, and there are listed for people, are the pitfalls.


And then, finally, I didn't yellow is the end point is the toxicological and that was previewed in the table before. And for both contaminants, the selected and on was some type of immune response. And, specifically, this was a response Due. Vaccines. So, again, very squarely within the physiological regulation updation of human beings, and then, if you look at the types of numbers that are included as race, you can see the wildlife by 10, the nine milligrams per kilogram body weight per day incentive while I still like that. So you think, oh, whoa, zeros, there are digit. But.

If you think about general environmental contaminants out there, maybe some of you in most of you have worked with, such as the PCB, specifically, quite toxic PCB 126 that's a par with PCB and esthetics. But I'm not saying that PFAS, a false start suggests PCB 126. But I think just I think it's a good reference to think about the relative magnitude of type of numbers does help the wiser. So, next slide, please. Level of low quicker, and this is really quick, insert. The other one was concerning the protection of non cancer endpoints. EPA also looked at the cancer end points for PFAS. The agency did not find strong evidence, does suggest it, perfect, but because there is, and then the cancer slot factor was established.


And, again, doing the same exercise as previously, just to check, Hey, I'm not familiar with this numbers is good or bad hire. Well, well, they're comparable within the range between, again, PCBs and dioxins, specifically to So, quiet impressionists that we're regulating quite low-level, and certainly within well recognize toxic compounds in environment. Next slide, please. So, finishing up, real quick, now, really quick, insert here on the rocket source contribution. You can see that EPA's number is the lowest and the way to provide capitation is most stringent, and then in comparison, you have other states, relative sales contributions listed. But keep it in mind that most people exposure based on multiple dietary exposure studies is from from water, it's not even the stack and maybe the third most important exposure route. Next slide. But, definitely, The reason why those health advisories are quite low. It's because they're based on subclinical and for selection, specifically, the response to vaccines.


And I would argue that there are certainly within the physiological management adaptation control of an organism. Then further than that, just because there's a change in immunological response, it doesn't necessarily mean that there is a clinical or pathological Outcome. So that's that the link is uncertain. Of course, recognizing the need for sufficient conservativism to overcome uncertainties, Nevertheless, those numbers are quite low.

And then, finally, if we wrap our head around the types of levels, in terms of endpoints, we're looking at definitely going to the contaminants as toxic as PCBs and even so, with this, I thank you very much for calling in, and I'll hand the presentation. I guess, back to niche. Thank you.


So I'll step in now for the next sections, I'll talk about laboratory methods and detection limits with some, some comments on how things have changed over time and, and approaching that part per trillion barrier. So reframing some of the analysis laboratory methods and looking at it and in the context of of where we're going with this Webinar. And also provide some comments on treated ability of PFAS and water at or below that part per trillion threshold.


And that'll follow that up with our final section on our evaluation, into the unintended consequences. Now, I'm starting off with a survey of currently available laboratory methods. These are, this is focusing on the EPA's methods for PFAS table. Summarizes current methods, again, focused at EPA methods, but also the why they use EPA, the non EPA 5 37 Mod included for a fair bit of comparison here but there's still some elements of these methods switch.

Maybe some of which look a little esoteric on the surface, but I think there's there are I'll have some relevance to our discussion today and I'll be referring back to a few of these methods as we go through this and in some of these elements of these methods as we go through this. So, I've got a handful of methods shown here going to the table. The matrix that each of these methods is applied to is shown. We have 537 and 533, which are intended for drinking water 827, 633, you have a broader set of matrices that they can be applied to.


And then the five theories have been modified, which, since it's not an EPA specific method, anything goes it, It is, as the laboratory has developed it, and anything you can throw at, them, they've actually been able to figure out a way to apply some version of my, 5, 3, 7 modified. you. Going through the release dates here. This is summit set up in somewhat of a chronological order. We started off with 537, hard to believe. That was way back in 2009. We had our original version of that method modified and it was updated in 20 18 with an expanded analyte list. 533 was added to for drinking water in 201980, 3, 27. also. Finalized 20, 21 633 isn't a draft method. There's been, it's been in draft, has been a few revisions of the draft and, and things are still moving forward, additional drafts are expected before that goes final.

In terms of analyte lists, they've generally increased over time, starting off with a 14 and the old, 5 37 method, up to 40, PFAS analytes in the recent draft for EPA 1633. The quantification that the event, the approach, used to quantify samples has also changed a bit over time and we see that the two versions defer to your external standard versus isotope dilution. External standard is kind of the classic approach. Worked fine for the old chlorinated solvents, part per billion type of analysis under most circumstances. But, um, for for ... due to the complicated chemistry and the analysis that we need to do in the slow part per trillion level, isotope dilution become the gold standard.


Isotope, dilution involves injecting samples with a cocktail container containing isotopes of the target compounds that are analyzed in the same run as the Target Analytes and provides a method for quantification within each sample, which provides much better, more accurate results at low concentration can I can control for Matrix interference type of effects.

Preparation is another important factor to keep in mind, as we look at these different methods to version is shown here, solid phase extraction versus direct injection, the solid phase extraction to as the name implies that it involves it's used for water samples or aqueous liquid samples. The waters run through a filter that accumulates the PFAS compounds and then... into a solvent. So, basically, what that does is concentrate the PFAS constituents from a large volume, into a small volume, that can then be analyzed. There's some difference in sample volumes that can have some impact on the reporting and detection limits. And going through all this, that's really what all this is leading to, is the reporting or the detection limits for the samples.

And, I mean, that's where the rubber hits the road here, is, can we accurately quantify our PFAS compounds at the levels that we need to, in order to compare to the standards that keep going to lower levels? As Andrew was talking about it. Briefly, the difference between reporting detection limits for those who don't work with these on a regular basis. The reporting limit is the lowest level at which a compound can be accurately quantified detection limit is a lower level than the reporting limit, its value at which a compound can be detected, but would be reported as an estimated quantity.


So, typically, how the shows up in a lab report, if it's compound, is present, between the method detection limit and reporting limit, you will see a J flag and that J is defined as an estimated value. But briefly running through these methods, we really, from my experience, have generally seen fairly similar reporting limits and detection limits.

There's some overlap, a little bit of difference here, but, generally fairly, fairly similar to what we can achieve, what we've seen achieved and conversations with, with labs. How they're generally able to approach this, with, with some differences, and I would invite any folks in the labs who see this and have any doubts or questions on this. Please feel free to chime in in the questions, and we can talk in the Q&A.

So, very briefly, some overview, thoughts on the different methods. The EPA gave us this original 537 in 2009, that was used for the first ... Monitoring program. Andrew mentioned this in his presentation earlier that the unregulated contaminant monitoring rural part of the Drinking Water Act Assessment for, for MCOs part of that process, the AUC M R three. The third implementation. That program, from 2013 to 2015, use the EPA 537 Method EPA, added 533 as a drinking water method in 2019 and improvement on 537.

Because it includes the isotope dilution, which, as I mentioned, is, a better, more accurate quantification method. A combination of these methods is what's being used on the earth. The upcoming are actually just getting underway: u.c.r. our program, that use EMR five is running for 2023 to 2025, using both of those methods in order to get the analyte list of 29 compounds.


Also speak briefly here to 633, which, as I mentioned, it's in a draft form. The third version of the draft was released in December of last year, and that included Monte lab validation for wastewater. And now, we're awaiting the next version, which is supposed to have the multi lab validation for additional matrices, including the groundwater and surface water. The method can theoretically be applied to those samples. Once it gets the validation is complete, the confidence in those data will be enhanced.

So that's expected early this year and according to the EPA schedule a finalized version that's going to include the other matrices solid tissue matrices. We expect that to be released later this year. As noted here, 633 did expand the standardized analyte list pretty significantly over what was being previously reported to the CPA methods.

As we are dancing with this part per trillion threshold, I wanted to do, is take the slides just to take a look at the EPA's health advisory levels, look at how they've evolved over time, and how that relates to detection limits that we've been able to achieve.


And, and kind of plot from the comparison. So this slide shows, is, I can see concentration on the Y axis versus time by year, on the X axis. And these are the two lines. The blue line is PFOA, the reddish dashed line, PFOS. And this is showing how the EPA's health advisory levels for these compounds is changed over time. Additionally, a provisional health advisory levels, on the 600 part per trillion range. That was dropped to 70 parts per trillion as so-called final health advisory levels in 20 16. And then, as Andrew mentioned recently, we have these parts per quadrillion levels, updated interim health advisory levels. So through this time, and this is from my experience, that, that the two gray bars that you see at the middle here illustrate the general range that we've seen for reporting limits and met the detection limits, and haven't changed significantly since the the early 537 method. So, although the the value is, reporting limits haven't changed significantly, and there's been an incremental improvements. What we have seen is a very, in a notable increase in our confidence in results, as we get to that lower part per trillion range.


Now, This might be doing as much to improved sampling methods and identifying materials that can be sources of PFAS, as much as improvements in other analytical aspects, such as instrument sensitivity. Also, in conversations with labs, they've greatly improved on identifying and eliminating contamination sources, and on their end, as well.

Yeah, So, although maybe the reporting limits haven't changed significantly in terms of where they would show up on this on this chart, well, another area that has changed significantly is the analyte lists. So, are we used to see 1 to 2 part per trillion? For maybe 6 to 14 compounds, You can now get to these levels for 40 or more compounds, which might be expected to change over time. There's an error on this chart. You see here this EPA MCL with the question mark just indicating that in the near future, we expect to see the EPA come up with draft MCL. So Andrew covered in nice detail previously.


In terms of the detection limits and the timing of EPA's MCOs, and also factoring in the updated at the Interim Updated Health Advisory Levels at the parts per quadrillion level, think when we reach, when the EPA released these parts per quadrillion level, health advisory levels. one thing that we notably did not see was a race to lower detection limits. And I think in part, that may be because there's a lot of infrastructure in place and we're pretty well anchored. I'll talk a bit about this in a little bit more detail on the next slide, in terms of some limitations and trying to go deeper below that, that level.

You and I just wanted to frame up the ... monitoring that was done as part of this in terms of the timeline as Well, and this shows that the time over under, which you see MR three was conducted, and ... is is being conducted, and this is the the publish detection limits for PFOA and PFOS during that time. And the one point I wanted to make on this one is that the ..., the use of our three was conducted under the original provisional health Advisory Levels, 600 parts per trillion.


There are a lot of drinking water systems where detects occurred under ..., these reporting limits, which were 20 to 40 parts per trillion, So basically the order of magnitude lower than the those professional health advisory levels. When the EPA released these final Health advisories in 20 16, there were several drinking water systems. whose water became our sales airports contaminated overnight really, literally overnight, because of the change those health advisory levels, and that created some kind of a panicked response to be able to meet those levels. Now, moving into Use EMR five, the EPA has released these much, much slower interim updated health advisory levels. So now we're in the part per quadrillion and so we're dealing with detection limits that are in fact orders of magnitude higher than those health advisory levels.

So, basically, any detects that occurs under ... five is going to raise red flags, noted. That the first is a health advisory level. Not an MCL. So an MCL has come in, that's going to really set the standard for comparison. OK, so speaking to What does it take to analyze the sub part per trillion levels?


We've talked a bit about the currently available methods, and the reporting limits are ranging from 1 to 4 parts per trillion of Reporting. Amendment's, method detection limits, can get below that one zero point two to one part per trillion level. And, as noted, the sub part per trillion health advisory levels haven't really directly changed much from what I've seen in terms of reporting limits currently available, so thinking about what could be done in order to try to push those.

Detection or reporting limits down. one thing that jumps right out kind of the low hanging fruit is larger sample volumes. As noted, some of these analytical methods use, the solid phase extraction to concentrate PFAS So, if you run a larger volume of water through that solid phase extraction filter and then extract that into a solvent that you can reduce detection limits.


So, for Curiosity, ran some quick math here on what it would take to get to that four parts per quadrillion level. So this is based on current the current methods that require a 250 to 500 milliliters sample and then reducing the detection limit by a factor of one thousand. So, it's really the difference is just a proportional calculation. Take 500 milliliters and reduce it by a factor of one thousand.

In terms of detection, limits means multiply the sample size by that factor of 1500 milliliters becomes 500 liters, basically of a sample or convert it to gallon to 130 gallons. So, if you wanted to go this route to get to four parts per quadrillion detection, limits be prepared to collect a couple of 55 gallon drums plus a little bit more in order to get to that level.

But, there's more, that can be done that, just collect larger samples on newer generations of instruments, I think they are being made with more sensitivity there, maybe some options in terms of better extraction, or smaller extract volume from the SPE device, the solid phase extraction device. Oh, these are really maybe provide able to provide incremental changes, but not the orders of magnitude that would be needed to get to those levels. And regarding more sensitive instruments as well.


It's worth pointing out that the laboratories are putting huge investments into new instruments, current, generation of instruments, to be able to keep up with the ... demand that's underway right now. And my understanding is that's pretty challenging to do it. There's just becoming so much more PFAS sampling being done. So there's a big investment in the laboratory infrastructure to be able to analyze at these current reporting limits.

If there was a big push to replace the instrument's, but something that might be able to analyze lower that would be that would be messy I guess I'll put it that way. And I think that's a pretty major understatement. There's also an important consideration here to this last bullet on here is how clean are your blanks?

The analysis and the processing side is only one step, and the entire process of generating a sample. And it's challenging enough from our experience to be able to make sure to be able to control every step of the process to avoid PFAS impacts, because they are so ubiquitous in clothing and sampling equipment, and all that.

So, yeah, I will leave out there and move to the next slide, treatment at the sub part, per trillion level. So, I'll talk briefly here on this. We've covered in more detail in previous webinars, in the intent here, isn't to go into detail on how to treat PFAS. But I'll just cover some high level points and address the idea of treating PF asset this level, getting below two parts per trillion.


So really, at the well established technologies for treating ... and water, primarily granular activated carbon or ... ion exchange I X, and high pressure membranes. All of these are demonstrated to be able to treat PFAS two to the part per trillion level. I would note that, really, the treatment efficacy is, is controlled by the detection limits. That's something that we see as part of the directive, in terms of treatments, is treat, please tweet PFAS to, to detection limits. These technologies are able to get there.

But the challenge is that there's uncertainty in terms of what happens when you go below that Part per trillion level. And in the next section of this, I'll actually go into that in a little more detail. We did an evaluation of other impacts, in terms of when we try to treat fast to those levels destruction. I'll just say that there's a few destructive technologies technologies that can actually destroy, erase the molecule of ..., there are generally not effective when you're trying to treat this very little part per trillion levels. They're just very, very inefficient. So generally, the approach that might be taking us to use one of these or separation technologies and couple that with a destructive technology where the destruction technology can be used on the, the concentrated the concentrated waste stream that's generated.

Summary on what was covered in part three. So as noted, and is pretty well understood at this point, our analytical methods continue to evolve.


There are several methods out there, and we might see how things are going continue to take shape, but we expect 633 to become finalized here within the next year. And perhaps the drinking water methods will become come merged at some point 533 was expanded. To include compounds from 537. And then the folks participating using my five, don't have to analyze the two methods. That would be appreciated, but that's something that may happen in the future. Current methods are at or near that one part per trillion threshold.

Reducing detection limits, this is possible through improved analytical sensitivity, increasing volumes, but we really do need to consider the other factors, That's the existing instruments that would have to be eventually replaced, And, and then you also need to consider ubiquitous PFAS and how to control that, in terms of keeping our samples clean at the levels that would be needed to go to that lower detection limit. Also, noted that treatment to low part per trillion levels might be feasible, but additional challenges are part of this.

Now, as a society, we've read a lot about the ubiquitous presence of PFAS, and not without reason, or also fretting a lot about climate change, and, I don't know, I don't want to speculate, But, which is more worthy than the other, but I guess it's an indication how good we are as a species inventing something that might be helpful and then producing way too much of it.

But so moving on, We've titled slack section has unintended consequences to look at an evaluation that we recently did involving the calculate calculating of greenhouse gas emission emissions associated with lower Pete best treatment goals. This evaluation focused on the state of Maine, which was part of the purpose, and that what we're tasked with for this project.


But the evaluation is broadly applicable due to ongoing widespread initiatives involving both PFAS reduction and greenhouse gas reduction. So starting off with a couple of comments about greenhouse gas emissions, and I don't think there's a need to go into this in any great detail at all. That gets pretty well under understood, but that there are several state level and EPA, greenhouse gas reduction initiatives underway, not the least of which comes from the Inflation Reduction Act, which included this greenhouse gas reduction fund. one number I wanted to put out there, because I will refer back to this in the presentation, is the per capita CO two equivalent footprint in the US 15 metric tons per year. So some of the calculations you do will be referring back to that number.


Another question that this work was designed to address is shown here, What does the cost in terms of greenhouse gas emissions of this ultra low treatment levels? This is this: in the graphic shown here. So, it tends to be attempted to be a visual representation of, of our research hypothesis here, where the concentration, which is something of a surrogate, for, for risk, is: on the Y axis versus level, of water treatment on the X axis.


And our hypothesis going into this is that, uh, PFAS can be treated, ultra, ultra low levels. but with increasing water level treatment, there's going to be kind of a diminishing returns. And as we get to those ultra low levels, the greenhouse gas equivalent footprint, which is basically the footprint of what it takes to treat PFAS to that level will begin to take off exponentially. Now, this analysis is focused on the state of Maine.

And there's several reasons for that, which I won't go into in detail. But suffice to say that Maine has an interim drinking water standard which is 20 nanograms per liter for the sum of these six compounds. Andrew referred to this presentation as well, where in some circumstances, the sum of certain PFAS compounds are being used. And that was the case here for Maine with the interim drinking water standards. And they do have are in the process of valuing these for a state specific MCL. So, as part of the reason that this analysis focused on, main was to do this analysis and get it, publish it, get it into the discussion for their there for their evaluation.


So, providing a, probably oversimplified overview of the modeling that was done, but enough to give an idea of how this approach was taken, and we looked at both domestic and municipal water supply scenarios. The difference between those scenarios being that, the number of users, and that, the volume of water that was needed for treatment, and that both are normalized to one capita basis. and assuming gac is tied with existing cheap water supply system as well, So, the assumption here is that we aren't designing water supply system from scratch, but the EAC is not included on the water supply system, at this point that there's no need to have some treatment. So this is being added to an additional an existing system.

Inflow concentrations estimated from the State database. The target treatment level range we evaluated started with that 20 parts per trillion level that that some of six compounds and then both increased and decreased it by factors of 2 and 10. So, the values that we looked at ranged from 2 to 200 nanogram per liters. And, again, that's not a single ... compound as the sum of the six PFAS compounds. The Calculator got quantity on an annual basis, and we calculate the quantity using a model this published modeling approach by burkhart et al, which follows the friendly isotherm, and then calculate greenhouse gas footprint using sideways software and published, like, cycle analysis values. Now, the next three slides summarize the model output, and in different ways. So, this is the shows I'll put from the first step of the evaluation.


This is the calculation of the carbon quantity needed to achieve these different, different target treatment levels. For some of six compounds, this ranges from 2 to 200. In terms of that, some of six concentration, we voted to carbon products. one was coal based ones, coconut based. And this shows that when we get to these very low treatment levels, the quiet of carbon needed to achieve those treatment does, in fact, go up significantly, that the treatment efficiency becomes much less at these extremely low levels. Next slide. And then this takes this analysis step further, where we, the previous slide, showed carbon quantity, and this converts that carbon quantity into the greenhouse gas emissions footprint. So that's the Y axis. And these shows that the greenhouse gas footprint on an annual basis. Each of these pie chart shows how the greenhouse gas emissions break down, and this is based on published information, in terms of the production and use of activated carbon and calculations that included transport. So, that's what this shows that I'll cut to the chase, it's the production of activated carbon. That's basically three quarters of the emission footprint for activated carbon. And from these results, we can kinda we can convert these results and look at them in terms of that graphical hypothesis that we showed previously. And this shows, really does This does follow the trend that we expected, that it would, on the left-hand Y axis, some of six concentration, ranging from 200 down to two and then the resulting greenhouse gas footprint.

Shown on the right hand, Y axis, needs two charts, charts showing one, showing the coal based Act, others on the coconut based jack. Then we can take that, the greenhouse gas footprint and normalize it to the 15 metric tons per year. That's the standard per year per user, US.


I think what's fascinating on the side, is that we see in the worst-case scenario treaty to two parts per trillion using the less friendly version of the ..., the two that we evaluated, we can actually match the per capita greenhouse gas footprint 1 to 1 for actually doubling the person's greenhouse gas footprint. And even in the better case scenarios, retreating to those extremely low levels. We may see an increase of 10 or 30% inter in terms of greenhouse gas. So, it's a pretty sick, very significant difference. In terms of gas production. Once PFAS, treatment levels start to go to those levels. Next, slide.

And we've, we're running out of time, so I'll just really cut to the chase here in terms of via the summary. is that the key point here is that the greenhouse gas emission can be significant. I wanted to make the case here that we aren't advocating that PFAS treatment should be ignored, but also that the greenhouse gas footprint, as part of the ... treatment process, should, should not be ignored, ignored that, it can be very significant.

And this really comes down to trying to turn these charts into which, which risk is society greatest able to switch. And the next question. I'm addressing PFAS, Greenhouse Gas PFAS, cheap, and a few thoughts here in terms of the path forward and questions that can be addressed. So as addressing this part of the presentation, what treatment levels are warranted based on toxicology data. Then I think building on that, but just evaluate the question. This evaluation is trying to raise, is, is it fair to accept some risk in exchange for reducing the greenhouse gas footprint?

There's more that could be done, looked into to reduce the error, increase, the efficiency for PFAS treatments, which might include impedes, decreasing the efficiency, or looking into alternative technologies, that might be able to treat PFAS more efficiently, in terms of greenhouse gas.



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