Why PFAS Matters: Shedding Light on the Invisible Threat in Our Daily Lives

Dr. Alex Le Beau [00:00:00]:

You might not realize it, but we are exposed to dozens of hazards every day. Can any of these hazards negatively impact your health? Definitely. This is the exposure scientist podcast. My name is Alex Lebeau, and here, we answer your questions and Concerns on what you may be exposed to every day. Welcome to the Exposure Scientist podcast. The views expressed in this podcast may not be those of the host or management. This podcast is for informational purposes only and should not be considered health advice. It is recommended that you consult an exposure scientist to discuss the particulars of your exposure scenario.

Dr. Alex Le Beau [00:00:41]:

Hello, everyone. I'd like to welcome you to today's episode. Our guest today is doctor Giff Johnson. Doctor Johnson currently is a program manager for chemical management and health effects at NCASE. He also serves as an editor for Hamilton and Hardy's industrial toxicology 6th edition, A renowned reference text originally printed in 1929. And he also serves as past president on the occupational public health Specialty section for the Society of Toxicology. As well, doctor Johnson has managed several federally funded research projects as principal investigator. He has presented research at international scientific conferences and has participated in scientific communications with state and Federal regulatory agencies.

Dr. Alex Le Beau [00:01:23]:

Doctor Johnson, I'd like to welcome you to today's podcast.

Dr. Johnson [00:01:27]:

Thanks. Nice to be here.

Dr. Alex Le Beau [00:01:29]:

Today, we're here to talk about, PFAS. It's a very topical discussion of what's going on in the world. For those that do not know, there are lots of chemicals that are under the umbrella of PFAS, and PFOA, they are typically referred to as per and polyfluoroalkyl substances, and there are a number of them. And doctor Johnson had experience and knowledge in this area, so I invited him on here today, to discuss them. So, doctor Johnson, if you could, just kinda give a A brief history as you know it of the use of PFAS and how how chemical manufacturers and downstream companies may have used the materials, and why it is of importance or receiving some scrutiny today?

Dr. Johnson [00:02:20]:

Sure. The the use of PFAS compounds has, existed since, it in a large, extent in the 19 forties and 19 fifties, we started using these as, highly temperature stable, compounds for nonstick, Coatings on pans and pots and things like that. And we found very quickly that they had a number of industrial and consumer uses. They were Very heat stable. They were, very long lived. They didn't break down easily in the environment or on the products they were intended to be used on. And they confer grease resistance, wetness resistance. They, are able to, withstand heat.

Dr. Johnson [00:03:07]:

So if we're talking about, like, its use in food contact materials, you can line a, popcorn bag With PFAS, and you can cook popcorn inside of a paper bag and not have it catch on fire because you have this very heat stable, grease resistant material there. But also it's on anything that confers wetness resistance. So whenever you get clothing and fabrics and things like that that repel water, typically that As in historically been a PFAS compound, we were thinking about things like, high performance firefighting foams, And this is where we really get into our current interest in terms of an environmental contaminant. We discovered that, Department of Defense sites in you know, throughout the last 30, 40 years Had not only been, you know, storing these a triple f firefighting foams, which are very high performance and they have a very, useful Purpose in on an air force base when an airplane is on fire, not just anything will put that fire out. So you need something that is very high performance to, put out fires in certain situations in various types of military and industrial, processes. But, unfortunately, what they what occurred on DOD sites often was that they would train with these phones, and they would not capture the phones and allow them to, simply, you know, disseminate into the environment, and they would ultimately contaminate the groundwater to some extent. And because of the nature of these compounds, they are fully fluorinated or, you know, partially fluorinated or fully fluorinated Carbon chains. The carbon flooring bond is very strong and very difficult to degrade in the environment, so they persist for, decades potentially, and and take a long time to break down.

Dr. Johnson [00:04:56]:

So our use of these compounds It has started to become interesting from an environmental contamination perspective in the sense that once they escape into the environment, they do persist for a number of years, and they are so broadly used in consumer products and industrial products That we now have a situation where we have at least a small amount of environmental contamination in most parts of The, North American continent, particularly in surface waters and soils and things like that, that, you know, we've become very interested in what the potential human health ecological effects of that contamination might be. And so we've seen in the last decade or so, significant ramp up in both Research into the potential health effects and ecological effects as well as, regulatory activities surrounding how these compounds should be used in industry, should be found in consumer products, and how they should be managed as an environmental contaminant.

Dr. Alex Le Beau [00:06:00]:

I appreciate that. That's that's a great insight and and great introduction to the background of it. And, I I think a lot of What is going on today and and what people are observing as, you know, more of a recognition of it. You know, as technology has is improved. We're able to detect the lower or smaller and smaller amounts of the material. We're identifying that, as you said, there is more Distribution of it than maybe what was originally identified, in the in the groundwater, in the in the soil, in different, contamination aspects. Can you speak on the evaluation of those materials and identifying in the the sensitivity that has increased in those detection processes?

Dr. Johnson [00:06:44]:

Sure. So in in solids, when we're talking about, like, Products that we're looking at typically in hunt the hundreds of parts per billion as a detection limit, For instance, in in products that you might try to assess as to whether or not there's intentional addition of PFAS or nonintentional addition, you know, simply from contamination of of other, you know, nonrelated sources to production. A 100 parts per million threshold is typically used, and that's on a An aggregate basis of, like, total flooring or total organic flooring, so not individual targeted PFAS analysis. Where we've really gotten to low detection limits is in aqueous samples. So thinking about drinking water samples, or surface water, samples, and we have a couple of new EPA moo approved methods for that. 537.1 is typically our our Our drinking water analytical method and, there's, I I believe, almost 30 PFAS that are targeted in that, analytical method. And the that method, we can get down into the single digit parts Per trillion. And so that, you know, means typically we're looking at a a limited detection, somewhere around 4 parts per trillion, sometimes lower as as low as 1 part per trillion.

Dr. Johnson [00:08:10]:

When we're thinking about, you know, surface water, that might be more applicable To, 16/33 type of method where you have high solids, content dissolve solids where you might have to And a lot, you have to do some things to ensure that you're picking up the, PFAS that are in the aqueous portion of the sample as well as the salts portion of the sample. So it's a little bit different from the 537.1 methodology and to ensure you're capturing that total amount. I believe 1633 currently has, 40 analytes in it, and it is in its draft form with EPA, but it is in, I believe, its 4th draft form, so we should be seeing a final draft of that soon. Both of these, methods Have some, excuse me, some variability in them in terms of how laboratories deal with the prescribed methodology. There are some some different ways in which you can clean up samples and how you should dilute samples Before or after certain parts of the the sample train, process. And depending on the choices the laboratories make, our our personal experience has been that you can have some relatively substantial differences in the outcomes of of what you, get from your analytical laboratory By testing samples using these, you know, various choices they have throughout the the method. And the impact of this is that, you know, we have A lot of data from the last 10 years or so for surface waters to give us a sense of what, The potential environmental impact from PFAS has been, but that most of that data has been used, or has been Done using method 537.1 modified. So we remember, we said 537.1 is a drinking water method, so it's meant for Relatively pristine water not having high solids content, but they've made some modifications to it to try to adapt that to, having surface waters that have some, you know, interfering substances in it, and so those modifications are not always consistent among the laboratories.

Dr. Johnson [00:10:27]:

So it's it's Difficult to understand exactly how accurate a lot of this data that we've been getting is in the last 10 years, But we certainly see a range from low single digit parts per trillion in our surface waters to sometimes double digit parts per trillions. And in rare cases where there's been heavy contamination, we might see hundreds of parts per trillion and in some very rare cases, even parts per billion.

Dr. Alex Le Beau [00:10:53]:

And I appreciate that information and the the explanation. I I think this is where the the want and concern For human health and human exposure comes into play with the introduction or identification of these at such low concentrations. And I mentioned it earlier. Doctor Johnson is is one of the, editors of Hamilton and Harley's industrial toxicology. He is a a A trained toxicologist. So I'd like to get into kind of discussing, generally, the the health effects, the short or long term health effects that have been postulated, 4 PFAS exposure and why the detection of these materials at such low levels is being highlighted to Understand what people actually are internalizing and what the human health risks may be, from, ingesting those materials with such low levels of PFAS in them?

Dr. Johnson [00:11:47]:

Right. So there's a a variety of health effects that are Being investigated currently for, various types of PFAS, it's important to understand too that PFAS is a very broad class of Pounds. And so depending on which definition you use, some regulatory agencies are using a, you know, 2 carbon chain fully or partially fluorinated, substance or some are even saying, you know, 1 partially fluorinated carbon can constitute a a PFAS compound. But the they Range in the the carbon chain length. So they can be as much as, you know, 1 to 12, 15, and depending on, you know, some of the larger Polymers that can be very large, and they can range in terms of the functional group that is attached to the end of that Carbon chain. So predominantly, we think about, like, the carboxylic acids, like PFOA or the Sulfonamides, like the PFOS. So depending on the that those 2 components, the carbon chain link and the, functional group. You can have a variety of characteristics for these compounds in terms of They're fate and transport the environment, how they get absorbed into the body, how they're expelled from the body, their, rate of breakdown, you know, the What tissues they preferentially bind to.

Dr. Johnson [00:13:10]:

So there's a really up there's really a lot of individual, Toxicity characteristics for each one of these compounds. So I I just wanna make that clear from the outset that when we talk about the toxicity of PFAS, We're really talking about toxicity of individual compounds within that class, and it doesn't really make a lot of sense to group them all together because they have typically, different toxicological endpoints and significantly different dose responses depending on their individual configuration.

Dr. Alex Le Beau [00:13:41]:

I I think that's a great point, not to interrupt you. Sorry. Thank you. Is, you know, there is this want to group all of these constituents Together in 1 group, and I'll give you the example that you were just discussing. In the toxic substances control act, there are approximately 500, chemical abstract service or CAS numbers for PFAS chemicals. As you said, there's lots of different configuration changes, that can occur, And the regulators are wanting to put these all into 1 group, and that makes it difficult for the evaluation, as you said, with different toxicological endpoints. So with that information provided, You know, how how can the short and long term health effects, be evaluated? Is it is it is it better, in in your thoughts, you know, the some of them, and we'll get into this a little later about different thresholds that have been established, but, you know, are are some of the individual PFAS constituents, I'll say, causing Health effects that are more concerning, than others, and how are we viewing or how are we evaluating those short versus long term health effects based on The variety of different PFAS that can exist based on their historical historical use and deposition into the environment.

Dr. Johnson [00:14:56]:

Right. So it largely depends on data availability. So we have a lot of data for PFOA and PFOS. There are 2, very common 8 chain, degradates of big polymers that were used for a number of decades in this country. And so we've done a lot of Toxicological testing for them, there are is also some epidemiological evidence for these substances. And what we know about them Ecologically is that they have a pretty clear mechanism of action. They're, paroxysm, prolific proliferase, activators, And that produces a variable characterized, liver toxicity to some extent. We know it's related it can be related to some cardiovascular toxicity.

Dr. Johnson [00:15:42]:

But these effects occur typically in the parts per billion Contamination level of ingesting water in terms of these animal studies. And so what we saw as a result from those types of animal studies. We would get into, regulatory values in the hundreds of parts per trillion because they have a margin of Safety built into them so they're lower than what we actually, you know, find in the studies. So it's it's a very well characterized, disease way from exposures to these chemicals, but it occurs at a much higher dose. So what we're finding now is the People some scientists are trying to build an an evidence base for other types of outcomes like, thyroid issues, The the the the recent EPA, health advisory levels from a few years ago, they were based on Some, developmental issues such as seeking behavior in rats and rodents, and Those are less well characterized. There's not a very clear mechanism of action for those, but there are some some toxicological data that is suggestive that those effects might occur At lower doses than what occurs for liver, toxicity, which was, you know, what the primary, Health health levels were based on before that.

Dr. Alex Le Beau [00:17:02]:

Right.

Dr. Johnson [00:17:02]:

And more recently, people have become interested in some epidemiological Evidence for immunotoxicity. This is a lot less, clear as to what the actual impact for things like PFOS, The FOA are on on immunotoxicity. The the characterization immunotoxicity that they've been using is the the finding that Some after, vaccination for some types of vaccines, they would see some lower antibody levels And individuals who received the vaccination that had higher levels of PFOA or PFOS in their Blood stream. The problem with these studies though is antibodies are sort of like blood pressure. Right? If you measure it 3 times a day, you're gonna get 3 different numbers. And so if you just take this sample of, you know, an antibody level and a PFAS level at one time, it's not gonna be very clear what that means. The other thing is there's no evidence that any of these folks that had any of these antibody measurements were more or less susceptible to the disease that they're being vaccinated for. So the the basis of these studies is not actually a clinical outcome.

Dr. Johnson [00:18:15]:

It's that they didn't receive any disease as a result of the PFAS that was measured And their, their bloodstream. So it it's it's difficult to really understand whether or not This is a real effect. This is something that needs to be, you know, studied further, further characterized. And But the the the issue that we are concerned about from these studies is that these findings occur at very, very low dose levels. And so that is the primary reason why we have seen this evolution from 100 Parts per trillion levels that we think were safe when we were focused on liver disease down to, you know, slightly less than a 100 parts per trillion when we were focused on these developmental thyroid effects and then down to, you know, single parts per trillion Levels that people are suspicious of for these neurotoxicology effects. So that's The evolution of for at least PFOA and PFOS where we are are sitting.

Dr. Alex Le Beau [00:19:22]:

No. And And that makes sense. I know there are a variety. As you said, there are different, a variety of different outcomes that people have evaluated and attempted to identify. And, again, it goes back to your Statement earlier is lumping them all together makes it difficult, because, you know, they're you know, you need an understanding, of what constituents may be evaluated or may be in a contamination scenario to determine whether or not you're comparing apples to apples when you're doing Risk assessments, to make sure that you're comparing it to reasonable thresholds or what you're doing. Another thing that is Again, as we talk about, detection levels is there has been an increase or a a more sensitive, evaluation of those constituents In in human samples, in blood and serum samples to identify those at lower levels. So previously, where, again, we may not have seen those levels, when we're taking a human sample, we are maybe now seeing them that's aiding in this, association, pardon me, that People are identifying and saying, oh, well, you know, these outcomes must be done. The, must be the the the cause of the agent because now we're Seeing them whereas we did not before, and now we're able to kind of, make these, make these jumps, I'll say, to have to link these 2 outcomes together, the exposure and the outcome.

Dr. Johnson [00:20:48]:

Sure. I mean, there's it it's fairly problematic because a lot of these types of, outcomes are Fairly chronic diseases, but also because we've phased out largely these longer chain, PFAS compounds over the last few decades in most materials, we we've actually seen if you look at the NHANES data, it's the The CDC's, collection of various types of biological data from people, the survey data, those sorts of Of, you know, health related statistics and data, you've actually seen a drop in PFOA and PFOS and some of these longer chain chemicals in people's blood and other Biological matrices. So, you know, conducting if you're if you're trying to establish a relationship between these 2 things, but you're using, you know, health data from today and PFAS data from 20 years ago or vice versa. You're going to have a hard time making that relationship make a lot of sense because there there actually has been a substantial change in those concentrations. And and like you say, as as we go forward now, you know, the the the detection limits have of these Substances continues to drop as our analytical chemistry methods become more sophisticated. So we are, you know, Thinking about, you know, what what our real exposure was in the 19 eighties, if you're going out and looking for environmental data, That the limit of detection may be an order of magnitude or more higher at that time for looking at environmental data than they are today. So You may get nondetects in certain areas in the 19 eighties when we were sort of at our height of, You know, 8 chain, PFAS, environmental exposure. Whereas now, you will be able to measure them in down to the Single perf petroleum.

Dr. Johnson [00:22:45]:

So there's some challenges there in interpreting environmental data and how that has changed and how that has Potentially impacted health.

Dr. Alex Le Beau [00:22:56]:

So we've kind of talked about the toxicological endpoints, The hepatotoxicity, liver toxicity, any developmental effects, but one also thing that has been found by EPA in in a recent assessment, is the longer term risk of cancer development. I'm just gonna read you this information from an EPA document that was published this year, identifying the suggestive evidence, it says EPA has determined that PFOA and PFOS are likely to cause cancer, for example, kidney and liver cancer, And that there is no dose below which either chemical is considered safe. And they've lumped this analysis together, in their overall PFAS analysis? So I'd like to just generally kind of give an overview of, you know, the information that EPA may have been relying on or looking at, for this evaluation and the statement that, there is no safe dose of exposure.

Dr. Johnson [00:23:53]:

Well, I guess that that gets us into some specific data for PFAS, but also some general comments about how we evaluate health effects In a regulatory context. So for PFAS, there actually is some emerging animal, ecology data, which is the higher quality of data, as compared to epidemiological data, and we'll talk about that in a second. But, for an increase of tumors in, PFOA studies, the PFOS data is, I think, a lot Less, conclusive. And there's there's some challenges in interpreting some of these studies, but the the evidence is stronger for PFOA, I would say, than there is for PFOS even though I I believe that they're considering both of these to be likely carcinogens. So So one of the the reasons why we rely on animal toxicology studies for regulatory development as opposed to epidemiological studies, which Increasingly, it's being used by EPA to be the focal point of, you know, regulatory development and developing actually threshold levels for Regulation. So in an animal study, you have 2 groups of animals and they are treated exactly the same. They have the same day and night cycle. They have the same food, they have the same water, they have the, you know, the same living conditions, the same stressors.

Dr. Johnson [00:25:16]:

You You know, if there's not a group of mice that are smoking versus a group of mice that are not. So that all these these environmental conditions, they're all exactly the same. The only thing that's different between these 2 groups is the dose of the chemical that you are giving them to test their toxicity. So the one major point of uncertainty for an animal toxicology study is whether or not it extrapolates to humans because Rats are not people. There potentially are differences in the way that their their bodies treat a chemical and exhibit On the other hand, in epidemiological study, that is the one point of uncertainty that's removed, right, is that you know that humans are the subjects in that study, and so it's relevant to humans. However, within the human populations that you are are measuring, unless you explicitly measure and control for these Things you don't know if you know, how many people are smokers, are obese, are, They have a variety of other factors, you know, if their occupational exposure is impacting their cancer risk, if their genetics are impacting their cancer risk,

Dr. Alex Le Beau [00:26:22]:

you know,

Dr. Johnson [00:26:23]:

where what other types of environmental pollutants they might ex be be exposed to or anything along those lines. So Some studies do control for some of these things and that helps. But at the end of the day, Particularly when you're looking at the lower end of the dose response curve and you're looking for very small changes, it's very difficult to have high confidence And then in a, cancer study that demonstrates very low changes of, cancer incidence Between populations, even if there is, you know, differences in their, PFAS or whatever target chemical you're looking at, exposure level. So there there's issues reliability with the epidemiological evidence and particularly if they don't tie back to the toxicological evidence in vivo studies And, animals that corroborate that evidence, it's it's sometimes hard to know exactly what's going on. And the problem with the way we regulate carcinogens as opposed to non carcinogens is that for non carcinogens, we assume that there is a threshold, That there is some level below which anyone could be exposed to a chemical and not exhibit health effect. For carcinogens, We make an assumption, which is basically a regulatory policy assumption, not a scientifically based assumption, that there is no threshold, That there's potential risk all the way down to as far as close as you can get to 0 without being 0. So the only way you can get to 0 risk is to have 0 exposure. So because we make that assumption, we typically take data that is very high on the dose response curve To make our extrapolation to what might be a dose response at a very low level, and it can be several orders of magnitude.

Dr. Johnson [00:28:18]:

So we may be making assumptions about what the risk is at a, you know, 1 in a 1000000 risk level from a study that was really done in a 100 animals or a 100 subjects in an epidemiological study. So you're looking at a 1 in a 100 risk, and then trying to extrapolate what a 1 in a 1000000 risk might be. And so because you've made that assumption of no threshold toxicity, you are likely to get well, you're you're guaranteed to get Calculable risk even though the risk may be as low as 0 at that dose range.

Dr. Alex Le Beau [00:28:50]:

Right. No. And that and that makes sense. I mean, that's that's kind of the the How these types of studies go and when they talk about there is no level which is considered safe, you know, they a risk calculation can be done. But as you said earlier, Not only is there an extrapolation through that low dose, but there are also safety factors that have been built in in in this evaluation. You know, as you said, extrapolations from animals to humans, variability in the population. You know, there are lots of things that go into, doing a carcinogenic risk. So one thing that you brought up, was epidemiological studies, and I'd like to get in a little into that because there are those studies that have been done on populations, from I'll I'll say kind of Two different, exposure scenarios.

Dr. Alex Le Beau [00:29:39]:

You know, 1, is the manufacturer exposure scenario. There are there are manufacturers of of these Products, of PFAS products that are used, downstream in other other manufacturing, type scenarios. So there are epi epidemiological studies of those manufacturers or downstream manufacturers, and there's also, you know, very limited epi, as you said, from NHANES data, for evaluating exposures in the general population? So are you able to somewhat, you know, talk about what the epi studies are, the types that are out there and the, I'll say, the strengths of limit and limitations of those studies based on the population that they are, evaluating. Again, you mentioned earlier the control, is an important factor that goes into animal studies, which may be lacking in epi, but I like to expand on that related to, PFAS? Because there's also you know, there's the occupational kind of type of exposure, and then there's the general population type of exposure to this material.

Dr. Johnson [00:30:42]:

Right. So I I believe there are a few occupational, epidemiological exposures, but the the Problem with those occupational cohorts is that the exposure levels are very high. And so it's difficult to extrapolate what the outcomes might be in the general population from looking at, what we see in occupational exposure, and and that's, you know, where we find liver toxicity and things like that that occur at those very high exposure levels. And when we're looking at the general population, there are, a few ongoing cohort studies that are looking at what long term exposures to very, very Low levels are potentially I don't think we have good conclusive evidence on those studies yet.

Dr. Alex Le Beau [00:31:29]:

Exposure science covers a broad subject area, Including toxicology, industrial hygiene, and risk assessment. From occupational, community, or environmental exposure, Exposure scientists apply scientific methodologies to understand exposure risks and apply controls when necessary. We at Exposure Assessment Consulting have this expertise. Please reach out to us at info at exposureconsulting.com for a free 15 minute Consultation to discuss the specifics of your exposure scenario.

Dr. Johnson [00:32:02]:

There have also been some of the sort of cross Sactional studies that I like I mentioned, the, you know, the Faroe Islands studies looking at antibodies and The, you know, one time sampling of antibodies versus the one time sampling of the PFAS, blood level, to see if there's a relationship between those things. Those are extremely problematic because not only is there a high degree of variability in the outcome that you're looking at in terms of, like, antibody, concentration, without a sort of a temporal relationship to see you know, you you can't establish that necessarily in the same person that as a PFAS level increases, antibody production becomes less, or, you know, whether or not, Other factors that confound antibody production are taken into account. If you I mean, if if you look for I believe CDC has some some guidance on looking at antibody production, that there are a number of factors That can confound, antibody production such as, you know, simply having a cold, having Other types of of environmental exposures around you depending on, you know, if you're living in a place that has, Cleaner drinking water versus less clean drinking water, things like that. So if you're exposed to other environmental pathogens and things like that, That can impact your your baseline, you know, antibody response. So without taking into account many of those things that influence that, It's really hard to know if if small changes, like in some of these studies as low as a 5% change of antibody response, really related to these Chemical differences that you're measuring or to any of these other things that impact that outcome.

Dr. Alex Le Beau [00:33:48]:

No. And I agree. And, you know, depending on the manufacturer and Depending on even the the exposure scenario there, you know, there may be, in in the study, there may be, in an occupational Sending people may have a variety of exposures. It may not also be PFAS. They may work in different portions of the factory and do different things or just have different exposures on on On chemicals that are being manufactured there. So I think that's an important distinction as well as understanding, you know, how how regulators are relying on This information, what information there is, and how how you can best interpret it. Because, again, as you said, when you're looking at the cross sectional, that's just a point in time. You know, you're not looking for trends, and and what is what are all these trends kind of telling you? Earlier, we had talked about, say, PFAS Toxicity and the mechanism of toxicity.

Dr. Alex Le Beau [00:34:37]:

Based on, I'll I'll say, some of the studies, and the importance for exposure monitoring? No. A lot of the focus has been lately on drinking water and and talking about The the MCL maximum contaminant level, maximum contaminant level goals, MCLGs from EPA. Is there a way that you can just kind of Discuss, you know, the importance of identifying these materials, PFAS, in drinking water, what that means for any potential for bioaccumulation within the human body, and and why it's received such scrutiny lately? And I see news articles all the time you know, the PFAS detection in drinking water. What does that mean? Now that there's MCLs, you're gonna have to control for that. You know? What what does that mean for for the end user, for the person who's turning on their tap in their home, as far as risks and and how should they interpret this information?

Dr. Johnson [00:35:32]:

Right. Well, I I think the the title of forever chemicals in your drinking water is getting a lot of clicks. So we're we're seeing a lot of those types of titles posted on various, you know, types of websites and things like that. There there's been an interesting evolution in the MCL process, and I think it's been very convoluted and very hard for, the common person to understand, you know, what the real risk is here. So before we had the NCLs for PFOA and PFOS, we had the health advisory levels from EPA, which were 70 parts per trillion. That was a a level that was suggested to say, you know, if if you're below that, you or if you're above that, rather, you may wanna consider some cleanup And, you know, it was used as guidance to sort of indicate, you know, where we thought there was a good threshold to think about some Potential action if you get above that, because it was protective of these, you know, questionable, but some evidence For developmental effects and thyroid effects and things like that that were, being evidenced in studies at that time. So as the EPA went through the MCLG process, which is maximum, contaminant level goal so these are nonenforceable levels, but they are considered goal. If you are con if you're identified as a carcinogen, the goal is always 0 for those.

Dr. Johnson [00:36:59]:

Otherwise, it's a very, very conservative estimate for, noncarcinogens that are considered to have a a threshold of toxicity. When the EPA went through that process for PFOA and PFOS, they focused on these antibody studies from the Faroe Islands and which occurred at, you know, basically, the closest limit of detection in those media for PFOA and PFOS. And that brought them with an addition of, you know, the margin of safety built into these levels as to, like, Hertz per quadrillion level, MCLGs. So again, not enforceable, but this had an important Act on EPA's treatment of the health advisory levels. Health advisory levels are are supposed to sort of be based on what's the the lowest Regulatory limit that, you know, we have across various EPA agencies for this type of material and the Matrix that we're interested in. And because they got to these parts per quadrant levels for PFOA and PFOS in the MCLG process, They adopted those for the health advisory level. So now folks who are thinking, well, 70. Seventy is something that, you know, we can protect the health, we can get to that level.

Dr. Johnson [00:38:16]:

That's something that's manageable. We can do that. Now they've gone from 70 parts per trillion to parts per quadrillion levels, which are not measurable, And that's below the load of detection. So not only can you you know, is it is it likely to grossly overstate the health risk that Potentially is posed by chemicals in water in drinking water for, you know, these particular substances. You can't manage that risk at all. You can't create a risk management plan based on something you cannot measure. So the NCLG process Settled. Every everyone sort of suspected that, you know, these health advisory levels are probably not going to be long Lived simply because they're not particularly useful.

Dr. Johnson [00:39:01]:

So now we've we've completed the MCL And the MCL process got us to, more measurable limits for PFOA and PFOS, and it also used a hazard index some additional, PFAS, which we should talk about a little bit. For PFOA and PFOS, I believe we got down to 4 parts per trillion. And so 4 is measurable. But, again, if you are creating a risk management, prop program for, drinking water, You don't want to start doing something at 4 parts per trillion. Right? Because now you're right at your regulatory limit. You wanted to be doing something at an action level that's maybe half or a little less than half, like 1.4 parts per trillion. And so if you can't measure 1.4 parts per trillion, that's not a very useful action plan. Right? Because you don't know when you've gotten to your action level.

Dr. Johnson [00:39:55]:

So so again, these these levels are So low, they're really challenging for risk managers to, you know, create a program that they can actually operationalize in terms of protecting public health from from these chemicals. And, again, these these, Chemical limits are are based on this idea that they are carcinogenic. And now that PFOA and PFOS have been listed as likely carcinogenic, They now fall under a zero MCLG rule, so that changed the MCLG. And I do wanna mention, Before we get too far out of the MCL world, this idea that they had about the using the hazard index as a way of trying to group some additional pass under the MCL. So they have, I believe, PFBS and, 4 or 5 other, PFAS compounds that are Groups, there are varying chain links. They're of varying, functional groups in in terms of How they're structured. And so they have variable toxicological endpoints. They don't cause all the same health effects.

Dr. Johnson [00:41:02]:

They don't cause those health effects at the same dose response rate. Typically, when you use a hazard index approach, you are trying to add up various substances that Have a toxic effect on a similar end point. So if liver toxicity was your end point and, one caused a little bit of lizard liver Toxicity, the next one caused a lot of liver toxicity. You might add those 2 up to say this is that combined effect, and we want it to stay under The combined effect. Well, for these compounds, EPA said, you know, this is a feature, not a bug of of this new implementation of hazard index that we don't need to have common endpoints. And so we'll just add them all up because they are PFAS and likely to be the same. So There there were during the comment process of of this MCL development, there were a lot of people that, you know, made the comment that, you know, that's really not an appropriate way of applying the hazard index, and we should really be thinking about a better way to treat these chemicals. So This is, an issue that we, you know, are continuing to deal with in the sense that there is A regulatory desire to group these chemicals for some sort of simplicity of policy, but there is a a scientific, adversity to doing that because it simply doesn't match up with the data and the characteristics of these chemicals in terms of Toxicity and fate and transport and biological interaction and all of those various things that we consider.

Dr. Alex Le Beau [00:42:37]:

Right. No. I mean, that makes complete sense. And and and it makes it difficult, I'll I'll say, from a a drinking water perspective of, you know, what If if a if a public water utility has to evaluate these chemicals in these constituents, you know, as you said, how are they managing the risk? How are they evaluating this? And what does Risk actually mean, you know, you can have a a a theoretical risk that you calculated, but it may not be anything, I don't wanna say meaningful, Oh, but it may be have so many safety factors that are included in there. It's not a an appreciable kind of risk to evaluate. So you mentioned the regulatory framework. You mentioned how the EPA's, viewing this. Are there beyond EPA, I I don't know if you've We'll have the opportunity to look at other regulatory, findings and evaluations of these.

Dr. Alex Le Beau [00:43:31]:

You know? You've discussed how regular EPA is viewing these. Are there other regulatory bodies, whether it's, domestic or international, that you know of that may be evaluating them In a different way, not grouping them all together and actually looking, as you said, the the common mechanism of, toxicity, and and viewing them as the constituents instead of the whole?

Dr. Johnson [00:43:54]:

Well, it's a little bit all over the place. So there's many states during, EPA's 70 parts per trillion Health, health advisory level, period, thought that that level was not conservative enough, and so they went through their own process to develop some individual levels for Some targeted analytes, and it was typically a list of anywhere from 6 to 8 to maybe 14 various target analytes that they came up with. Lower numbers than 70. They could be as low as 20 parts per trillion down into the single digit parts per trillion depending on which state and which, Type of matrix you were looking at. So there's there are many states who have individual target analyte, values for certain PFAS. And this particularly relates to dischargers who are, discharging materials Into a water body, and these can potentially make their way into a permit. We haven't seen a lot of that happening, but this is something that's increasingly happening. With the addition of of 16/33 method from EPA, We will likely see more in NPDS permits requiring some measurement of PFAS if Just PFOA or PFOS as maybe as high as all 40 airlines that exist in that.

Dr. Johnson [00:45:19]:

So we're continuing to watch that, and I think that We'll see an increasing desire to measure and regulate, permitted, facilities for discharges of of these levels. There's other you know, the World Health Organization is using, I believe, in the hundreds of parts percholine are let me see. Well, we should look this up. We'll we'll have our whole organization has, It has, I believe, a 100 parts per trillion for PFOA, PFOS combined, And then also something like a 5 or 600 parts per trillion for an a total aggregate p fast value. Please check me on those numbers. I may have gotten those wrong. We we still see some substantially higher values. Like in Australia, they're in the hundreds parts per trillion for PFOA and PFOS.

Dr. Johnson [00:46:17]:

Canada recently has gotten Interested in regulating PFAS. And what we're seeing from them is a desire to group and a desire to, perhaps use a a lower, value than Will World Health Organization for that grouping of approximately 30 PFAS or so? And so they're still working through that process, But they they are certainly at that perspective of we should, you know, group these up and try to regulate them in the aggregate. So we're we're seeing a lot of diversity in how people are approaching the regulation of these substances. And there are various levels, I believe, of of good and bad in terms of the scientific robustness of how they treat individual substances As well as what they identify the need for additional conservatism to be in terms of what the margin of safety should look like Between where science actually says, yes. There's some significant health outcomes we should be concerned about and how far under that level the the regulatory value actually gets us to you.

Dr. Alex Le Beau [00:47:29]:

Sure. And just to provide context, it looks like based on the World Health Organization, they've, proposed values, provisional of a 100 parts per trillion for individually for PFOS and, PFOA, and combined, it looks like 500 parts For children, total for PFAS. That's interesting, and I and I think there's some you pointed this out, and I think this is an interesting thing to point out is, you know, It's not only the drinking water that you have to be concerned with. It's about the effluent from manufacturers or other types of that are discharging this water into water streams or waterways that, you know, they the and you could speak a little on this too, is they they Treat and clean these waters before they discharge. They have permits. They have thresholds that they have to meet. And this adds, I wanna say, it adds a burden to them, but it also makes it difficult in that scenario. And I don't think a lot of people really think about that discharge event, that it occurs.

Dr. Alex Le Beau [00:48:26]:

You know? People don't discharge like they did in seventies. You know, they have to take care of things. They have to, they have to ensure that there are thresholds that are met. And As you said, there may be some of these scenarios where the thresholds are such that they either can't and meet those numbers or can't even possibly even detect, those levels, as you said, for an action level earlier?

Dr. Johnson [00:48:53]:

Right. So A lot of the concern actually relates to the ubiquity of PFAS in the environment. So if you are, receiving water from your end your raw intake that contains PFAS, it comes out into your effluent. And if Mhmm. If your state is limiting you to 8 parts of your land, that may simply be what's in your surface water that that you're having to deal with. So that that can be a a a pretty substantial challenge. And when thinking about, You know, how you deal with something like that, you know, municipalities that provide finished drinking water to clients in in their City and the region, you know, are are constantly thinking about how do they get rid of that? The the remediation technologies that we have currently are kind of inefficient Inexpensive. And so for the difference between going from, you know, 70 to 8 Could be very, very substantially in terms of cost, and and maybe so much so that it's not feasible cost wise.

Dr. Johnson [00:49:58]:

And so We do need to think about, you know, are are we cleaning up these materials to an extent that is actually providing additional public health protection? Or is it you know, are are we not spending that money very wisely? Are are we spending money on something that's not conferring any public health benefit to anyone? So I I think it is very important that we continue to explore the science of the actual toxicity of these substances and understand Where we really need to be to confer public health protection.

Dr. Alex Le Beau [00:50:34]:

No. I I I I completely agree and understand it because, you know, As you said, those and the mitigation technologies, and I don't know if you're able to speak to that a a little bit what those are, but, you know, It it goes into, as you said, what's coming into the building. You know? There are new standards that you know, for, I'll say, buildings and owners and operators, and you're talking office building, whatever, that have a requirement to ensure the safety of the water entering the facility. You know, is this something that they're also going to have to potentially look at is, You know, what are the what are the PFAS levels? What what are the people being exposed to in this facility? Is there even a realistic risk? Because, again, You know, there may be maximum contaminant levels, but nothing's, you know, what is potentially Accumulating or being gathered between the distribution point for a public water utility and the end user. You know, are there as you said, are there even technologies on the somewhat consumer level that would even remove these materials, and is it even The cost effective methodology.

Dr. Johnson [00:51:37]:

Sure. Well, a good example of of concerns that individual facilities might have is some large industrial sites Provide finished drinking water to the workers, and so they are subject to the MCL. So they may have to achieve that that level of cleanup in order to provide continue to provide that water to the workers or anyone else that comes on-site. So in terms of remediation, the traditional technologies will work, but they're kind of expensive and inefficient. So granulated activated charcoal, that's something that It's sort of, all purpose cleanup of a lot of different kind of chemicals and wastewater. But the problem is is because it grabs so much other stuff Than PFAS, you know, if you're trying to go from 12 parts per trillion to 8 parts per trillion, you're gonna use a lot of granulated activated charcoal in order to to Get down to that level because there's so much interfering substances that that it's also pulling out that it's gonna be very you know, that you're just gonna have to use a lot of volume for that. There's a lot of use of resin ion, materials that, will grab PFAS in a similar way. But the problem with those kinds of technologies is it's typically used in the context where you wanna recharge that resin.

Dr. Johnson [00:52:52]:

You wanna send it out, have it cleaned up, and then put it, You know, back in and do that. With PFAS, you can't really recharge them so much. You typically have to destroy them the same way you would the the GAC, and that Presents actually another problem with it. You know, the these are heat stable compounds. Right? So to incinerate them, you need a very, very high level of heat to destroy that Carbon flooring bond and actually get rid of them, you're then concerned about air contaminants if you're doing that from some sort of incineration perspective, Or what else do you do with them? So once once you grab it out, what do you do with it? And that's, sort of one of the current problems. Same with reverse osmosis. Rever reverse osmosis is very effective, but it's very expensive if you're doing a high volume water. So a municipal water treatment plant or even, a large industrial facility that's discharging lots and lots of water, you're gonna have a hard time justifying the costs for that reverse osmosis.

Dr. Johnson [00:53:49]:

And then, again, that is going to create a slurry that has a high concentration of PFAS in it. What do you do with that? You gotta figure out a way to then get rid of that. And as we see, you know, PFAS fall under RCRA and CERCLA and things like that. The many of those things are gonna be now classified as hazardous waste, and so you're gonna have to deal with them under that context. So there there's What? There there's a number of experimental and emerging technologies coming down the pipeline, but as far as I've seen, none of them are at Scale to an extent that they work as well or better than the existing technologies.

Dr. Alex Le Beau [00:54:26]:

What's interesting is I think this is a good example of, you know, when you make changes to, control, something that's, in in the water like PFAS, it's always going to have different Downstream effects. Or for example, if you're using activated, charcoal or or carbon, you have to maintain a disinfectant level in there as well. You know? Is that Going to be impacted, that disinfectant level going to be impacted by the actions while you trying to remove PFAS? Is it more risky for you to have to provide, potable water that is lacking disinfectant, versus potable water that has a fix efficient, disinfectant in it, but may have small amount of PFOS as you said again, the, hazardous materials. Now you have to treat it, classify it a different way. It has to go through a certain So they got to handle it differently. There's always downstream effects. And I I think the overall thought is, you know, is the risk presented by these materials such that the actions that we are taking are worth it. You know? There used to be, for example, you know, as we were talking about MCLs, in evaluation of those, there used to be a component of that, well, economic feasibility in achieving those MCLs.

Dr. Alex Le Beau [00:55:43]:

So I think that has kind of, kind of been pushed to the side to say, well, we're we're not we're thinking more of the end user health Risk instead of the economical or realistic feasibility of establishing an MCL, based on what is technologically feasible and appropriate and reducing health.

Dr. Johnson [00:56:02]:

Sure. And and that's that's a challenge for industry, and I think that's, you know, an important reason why, You know, consultants in industry and especially academic researchers who, you know, have looked at this and think that maybe there's Some room for a better characterization of some of these issues to engage with EPA during these common periods and, You know, help them to understand that we we should look at all of the the uncertainties and potential biases and, You know, what what is the the best, most robust science we can look at to make a a high quality determination of where we balance that Protection of public health, margin of safety, and economic output. I've I've had many conversations with folks, you know, who would like to get a a permit extension to do new project. Right. So they wanna change their permit to do a new project. But as they're being compressed by lower and lower levels of discharges and things like it's very difficult to expand a project, which, you know, we we claim, and I think in this country and in sort of a bipartisan way that we're trying to expand our supply chains. Right? We're we're trying to build new infrastructure. So if we don't have the headroom in our permits to build out new infrastructure, it'd be very, very challenging to meet those goals.

Dr. Johnson [00:57:27]:

So we we really do need to to take a vested interest in not just saying let's let's have a race to 0 on what we think the toxicity of these chemicals are, Let's let's have a very nuanced and robust discussion of what's the best science, what's the best science to tell us, and Try to balance out those things because we all want protection on public health. That's you know, nobody wants to say, let's let toxic chemicals into the environment in a way that's gonna harm our Family. But we also want our economy to be strong, so we need to to find a very High robust, scientific basis to establish those levels.

Dr. Alex Le Beau [00:58:05]:

No. And then that makes perfect sense. Having something Scientifically defensible to support, these establishment of these thresholds. And I think that is, you know, where Kind of where things are going. So do you see on the horizon as far as any regulatory or filling in any data or knowledge gaps of this, do you Have you been made aware? Have you seen anything where we we may be going towards the ability to further delineate The the risks of the individual PFAS and and have something that may be more scientifically defensible if people are interested, and, again, in in reviewing permits, is this something where, you know, an individual permit secret say, you know, there's renewed research out there. I've done the risk Evaluation, and, actually, this shows that there's a decreased risk. I'd like to present this as something that, you know, I'd like you to consider based on current science, in allowing that permit? Where do you see the the the current and future, regulatory and research framework?

Dr. Johnson [00:59:08]:

Well, I I think, Yeah. States have taken a lot of action on PFAS in the last 5 to 10 years, almost in the last 5 or 6 years, I would say. And I I think we're starting to get some experience of what the impact on industry is from from those actions. So I think there is a vested interest now in in states taking look and saying, okay. We we don't want to destroy our economy by having a level that's unnecessarily low, that is not providing Additional public health protection. And so I I think states, as they move forward, you know, are going to take a more Nuanced look at you know, looking at individual chemicals and trying to find a happy medium where we get to that balance. Although there are certainly a a very, vocal group of people that believe that there is a substantial basis of evidence for low level regulatory values and, you know, the the folks that are conducting these epidemiological studies. And There are there's some groups that are doing some additional animal studies.

Dr. Johnson [01:00:12]:

We're gonna see a lot of more a lot more data coming forward In the next few years, that is going to continue this scientific discussion. And argument, I guess, is a legitimate way of saying it that, you know, Where do we fall? And but that's how science works, and that that's that's okay. It's good that we get more data. We wanna be cautious about what the quality of that data is and interpret it appropriately, But we want more data, and we wanna get to the right answer. So I think we will continue to receive more data. We'll have to be cautious how we interpret it, but ultimately, hopefully, We will get to a place that brings us that proper balance of protection and, industrial viability.

Dr. Alex Le Beau [01:00:51]:

I I'd love to get to that balance. I think this, balance is needed many times. I, the levels that are have been established Go down. They don't go up. But there have been the small instances where thresholds have been changed based on current science and current understanding, and, hopefully, This will be one of those scenarios. Any leaving thoughts for us today on PFAS exposure, health risks? I know we've covered a lot today, and it's great information. I thank you. So is there anything that you'd like to leave this discussion on on any listeners, for, any risks that they may be considering or thinking about with, PFAS in the news?

Dr. Johnson [01:01:34]:

Well, I I would say, you know, take all the the clickbait with the forever chemicals, you know, killing your neighbors with a grain of salt. It's probably overstating the the situation. You know, keep in mind that the the quintessential, proposition of toxicology is that dose response is what's important, not just the presence of a chemical. It's how much For how long? And we wanna, you know, keep in mind that we take a calm approach to regulating these substances and, you know, managing these risks. But also that PFAS is a very quickly evolving issue in this country and internationally, and we're going to continue continue to see regulatory developments in, like, land applied biosolids, very important for municipal wastewater treatment facilities, and other types The industry that land apply their their biosolids that come out of their facilities, it had it hasn't been a fit to, you know, agriculture and things like that. But, You know, we're going to have to be consider, you know, what that balance is for what we land apply and what gets potentially into the groundwater and those sorts of effects. We're you know, I've I've been to scientific meetings where there's concern about PFAS and recyclables, and some people have suggested maybe we Shouldn't recycle anymore. Like, is that really the balance that we wanna get to? I'm not sure.

Dr. Johnson [01:02:58]:

I'm not I'm not sure that that's where we wanna get to, but, You know, it's it's going to be a concern. It's going to be something that people are going to, ask ask that question. And, again, I think we should be very Concerned about throwing away good things for the benefit of getting a few parts per trillion extra margin of safety that probably doesn't improve anyone's health. And let's see. I mean, you know, just thinking about other matrices, The the next big thing I think that's coming down the pipe too is the impact of air deposition. I don't think anyone's been suggesting that an inhalational exposure route for PFAS is important, But people are being concerned about what is the impact of air deposition on water bodies to contribute to the overall, impact there. Of course, product product stewardship for PFAS is going to be a quickly changing area. We've already seen California institute a a couple of rules.

Dr. Johnson [01:03:54]:

They've Gone to a 100 parts per trillion for a coupe for the identification of intentional addition of PFAS for, I think, food contact materials, And as low as 10 parts per not trillion. Sorry. 1,000,000. A 100 parts per million for food contact materials, Ten parts per million for, effeminate hygiene products. And that basically is the limit of detection for the total Flooring method. We're also seeing, you know, a lot of complications with the total flooring method in terms of, you know, what the Accuracy, repeatability, reproducibility of of those results are. So we we wanna continue to be, mindful of what the necessity discussion is, what the regulatory discussion is, and what the analytical method discussion is because that will become very important in terms of Knowing what your situation is and whether or not you're being compliant with state and federal rules.

Dr. Alex Le Beau [01:04:53]:

No. And I and I appreciate that. I mean, I think you get a lot of good information there. I think it's it is something that I don't think is well explained, in the current news cycle, and I I'm hoping that the information you have given us today is Going to help some people and help with that explanation and make them understand or help them understand what the differences are, what the real risks are, what those levels actually mean. So, doctor Johnson, thank you so much for joining us today. We really appreciate your time.

Dr. Johnson [01:05:23]:

Oh, thanks for having me. I appreciate it.

Dr. Alex Le Beau [01:05:26]:

Thank you for listening to the exposure scientist podcast. You can connect with us at our website, exposureconsulting.com, where you can book To private consultation and send in any questions regarding any episodes for our guests. See you on the next episode.