Part 3: PFAS Data Analysis, Interpretation, and Risk Assessment

Webinar date: May 14, 2020

Watch the webinar recording below for an in-depth look into how to evaluate and validate data and to deepen your understanding of how successful data interpretation translates directly into effective risk assessment and management.

For more information, contact:

Andrew Pawlisz, DABT


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

Hello, my name is Amy and I'd like to welcome you to part 3 of Trihydro’s PFAS webinar series. Today's session is titled Data Analysis, Interpretation, and Risk Assessment. If you missed Parts 1 and 2 of the series don't worry, we will include links to those recordings in a follow-up email delivered to you tomorrow. For today, we have two speakers here to share practical tips with you related to PFAS data. First, Dr. Ken Ede of Oklahoma State University Tulsa will discuss data analysis and interpretation. Then Andrew Pawlisz, emerging contaminants subject matter expert with Trihydro will dive into real-world risk assessment considerations. 


Dr. Ede is a certified hazardous materials manager and has taught numerous credit and non-credit environmental seminars workshops and courses for Oklahoma State University. He also serves as the non-credit curriculum director for OSU’s professional development office for the School of Engineering previously. He served 18 years as the environmental health and safety manager for American Airlines.


And engineering center in Tulsa, Oklahoma, Dr. Ede thrust areas of research include hazardous waste management environmental chemistry industrial environmental sustainability and Industrial ecology Dr. Ede is also a member of the Hazardous Waste Management advisory counsel for the state of Oklahoma and for the environmental Federation of Oklahoma hazardous and solid waste committee, Dr. Ede. Thanks for joining us.


Today, we look forward to learning more. Thank you, Amy.


First I want to thank Oklahoma State University and also want to thank Trihydro for the privilege of speaking here today. And as Amy was saying if you have an opportunity after this presentation Trihydro on their website has some excellent other webinars prior to this one in to give it a lot of good theory and very practical applications.


So let's address and by the way also if you've ever thought about your master’s degree, here's my plug for Oklahoma State University. There's my email address. Please. Feel free to contact me. Today, we're going to be using a fictitious example of cowboy bicycles. It’s just a made-up company. We're going to talk about chemical analysis and a laboratory accreditation how to triage or samples blanks admissibility of evidence and courts of law in addition to that when we talk about PFAS.


I'm going to talk about the non-polymers and Cowboy bicycles has outgrown their current facility and want to purchase large Parcels of land from a bank to expand their operations. Cowboy bicycles asks you to conduct both a phase 1 and Phase 2 real estate assessment on a vacant piece of land.


They have made the purchase of this land contingent upon the environment on the environmental real estate assessment. Now imagine you are the seller but yourself or the seller shoes the bank they have already conducted their own real estate assessment the sellers report, which is the bank no contamination was found your report PFAS high concentrations was determined the bank now who they have purchased this piece of land as an investment.


Is now disputing your report.


So again, in this fictitious scenario review your goal was to determine if the groundwater and surrounding soils have been contaminated by either organic solvents such as perchlorethylene or heavy metals.


Therefore, your normal course of action would take representative samples soil groundwater and communicate with your favorite laboratory for metals volatiles and semi-volatile this is done on a daily basis generally I recommend 82 64 volatiles 8270 for semi-volatile test method 6010 or 6024 total medals.


As per ASTM e 1527 13 during the phase one real estate assessment you interview some neighbors regarding this vacant piece of land again. This was common.


One of the neighbors tells you that many years ago the fire department uses piece of land to conduct some training the neighboring remembers at some kind of white foam was used. You contact the client, which is the buyer, and they want both soil and groundwater tested for PFAS the groundwater by the way is brackish. What is also let's just stop right here. We talked about this foam this AFFF. It's patent was 1963. It's been in existence now been used by both civilian airports and military for over five decades. 50 years. So here's Cowboy bicycles. Again. You're going to take both soil and groundwater sample and test for PFAS your goal. Number one goal is to analyze for PFAS and non-potable waters, soil, and groundwater. Number two. You always assume there's going to be litigation.


So you need to ensure that the analysis will be admissible in a court of law. And generally I have found you go through discovery. Then you get deposed in a deposition. Then you go to trial.


We do you think about it most chemical analysis other than criminal and environmental samples is a very little chance of litigation. You have a garden or small farm and you want to check total nitrogen or total phosphorus or cation exchange capacity. The probability of getting involved in litigation is very small, but just like a criminal forensic laboratory as environmental professionals.


You have to assume all samples submitted to a laboratory will be followed by litigation.


I attended Oklahoma State University and I had a professor there and he used to say something very interesting. He said when you're done with an environmental report, read it out loud and write like you're talking to a judge pretend a judge is standing right there as you're writing. Let me expand my old professor’s adage sample. Like the judge is standing right there watching you.


Your chain of custody form like the judge will be reading it and most likely he or she will and every time you submit a sample to a laboratory assume you're going to be explaining your rationale to a judge. So let's go over the so he have Cowboy bicycles and let's talk about traditional chemical analysis. Cowboy bicycles uses chromium and they treat the chromium at the industrial wastewater treatment plan.


Let's just talk about one mole of chromium one mole of chromium is about 51.9 grams. What is interesting if that mold chromium is the smokestack the Clean Air Act has the jurisdiction if you want the chemical analysis you go to sw8 4846 test method 0061 has the prescribed methanol methodology. But instead you discharge it to the city's Sewer Department your PO TWP.


Locally owned treatment works all of a sudden out that mole of chromium is now under the jurisdiction of the Clean Water Act. You have to get a pretreatment permit. The analytical techniques are prescribed in 40 CFR part 136. If the city or Cowboy bicycles is now discharging that mole of chromium into this beautiful River all of a sudden now, it's under the Clean Water Act, but you need a different permit you need.


An NPDES permit and the analytical techniques are prescribed in 40 CFR part 136. Now let's just say the city of whatever city it is or municipality. They take that water with that mold of chromium and they are going to now provide drinking water to Cowboy bicycles potable water. Now that mole of chromium now that aliquot to water is under the jurisdiction of the Safe Drinking Water Act.


And the analytical techniques are founded 40 CFR part 140 1.23, but instead of this.


You make a decision that you are going to not discharge the chromium whatsoever. You're going to transfer to a truck and then ship it off to at is div treatment storage and disposal facility. You need to determine is that mole of chromium hazardous. If you now all of a sudden that mole of chromium is under the jurisdiction of…go to 40 CFR part 2 61 .2 for you. Look under SW.


And it specifically says you need to use test method 1311 TCL p and we're going to determine is it hazardous or not and in for chromium, it would be a d 0:07 if it contain 5.0 milligrams per liter or greater of chromium.


The point here to make here is that traditionally every federal and state permit requires you to use their analytical procedures in addition most states require you to use state-approved Laboratories therefore before submitting a sample to a lab you have to ensure as environmental professionals that the lab is certified to analyze that chemical parameter per the federal act or the permit here is a good example a pretreatment permit under the Clean Water Act. And this is actual real one but the City of Tulsa and you can see industrial pretreatment and you can look on page 3 of it.


It says here, you must use the analytical techniques found in 40 CFR part 136 and the laboratory.


Must be certified by ODQ, the Oklahoma Department of Environmental Quality. Almost all the 50 states have these requirements.


Therefore, all environmental samples have five conditions. You've got a sample it properly you have the field blank strip lines preservatives. You have your chain of custody form on the chain of custody. You must state what analysis you want and you must ensure that the analysis because it's is consistent with the federal act that has jurisdiction on that specific sample on that aliquot in the laboratory is certified for that analysis.


Now, let's talk specifically about Faust analysis and drinking water in potable water. Number one sample properly. A lot of people don't like the Michigan guidelines, but my recommendation if you're in Michigan, I would certainly follow their guidelines. If especially if it ends up in litigation number to you, if you complete your chain of custody form the analysis you want on the chain of custody form. We're going to specifically say under Safe Drinking Water Act.


We're going to use are chemical analysis test method 533 537 or both of them and number five the laboratory is certified for that analysis. The laboratory has to be certified in Most states to do potable water in your state. Let's talk about PFAS analysis again at the present time all PFAS analysis were designed for finished clean potable water.


There are no final today as to how to analyze PFAS and soils sludges non-potable water finished products or even something like boots. There is no analytical procedure. So we are / verbally we're like that that square peg in a round hole in addition under the Safe Drinking Water Act.


There are no MCLs at the present time EPA has established a health advisory level of 40 parts per trillion PFAS and PFOA only so let's talk about now are specific case PFAS analysis of soils or brackish water again. We're going to sample properly we going to have a chain of custody form and on it. We're going to have the analysis and here look at number four. There are no federal state regulations. How do you analyze PFAS and soils or groundwater and number five at the present time?


Laboratory is certified for PFAS for solids like a soil. So what are we going to do? We have we're going to develop a strategy. Number one. We're going to triage or samples. We're going to run the blanks first and only use 250 MLs. We'll talk about that in a minute. We're going to analyze brackish water using serial dilutions.


We're going to analyze the soils and sludges using a standard extraction procedure and we're going to understand the limits of these analysis and ensure that the laboratory at least is certified for PFAS analysis in potable drinking water. Let's talk about triage and why we do this right now most Laboratories are using a tandem Mass Spec liquid chromatography to analyze for PFAS molecules. The cost of a new one is about three hundred and fifty thousand dollars every day it's not operating.


It costs the lab up to $10,000 profit. Therefore, we have to help them protect these instruments. Unfortunately, or fortunately, were designed to analyzed finished potable water drinking water with low TDS (total dissolved solids) and low TSS (total suspended solids). Very clean water. This is why we need to work closely with our environmental labs.


To ensure we're not creating damage to their instruments just one sample with high PFAS concentration. You can contaminate that instrument for several days and it's very frustrating the easiest and most cost-effective method to protect their instruments is to triage your sample before they received in the laboratory.


And by the way, the word triage is actually a French verb in which all it means is to sort and I say that triage is simple as ABC. A is your potable water. This is what this instrument was designed to do 533 and 537 were designed for this matrix for the very clean water low suspended and dissolve solids. In addition, these potable water samples. It cannot harm the instrument of the laboratory.


These types of analysis with potable are the easiest to get down to parts per trillion range as a recommendation specially in groundwater, if you're not sure if it's potable water go purchase a TDS meter there under $50 if the T DS is greater than 500 milligrams per liter. Most likely you do not have potable water. You have brackish water begin if the sample is greater than higher than 500.


Per liter put it in Group B,


Group A potable water. Again, potable water has the lowest practical quantifiable limit for PFAS. The minimum aliquot size is 250 mL. We're going to talk about that just a little bit it do not allow the lab to use a sample size less than 250 mLs will talk about that. Just a minute.


Also Group B is the brackish water to give you a perspective of how common brackish groundwater is the all these green Hearts are brackish water.


Once the laboratory is notified that this is a group B. It's not drinking water. It's brackish their protocol changes instead of analyzing the sample as is the laboratory generally makes serial dilutions to ensure they do not ruin their instruments. Most mass specs do not like high suspended solids or dissolve solids after serial dilutions have been made the laboratory then can run the sample for PFAS.


They are two major problems with this: number one is it increases the probability of error and number two, it increases the practical quantifiable limit. Both of these are problematic but if you believe that the brackish water has AFFF and has greater than a hundred parts per trillion again. You want to notify your laboratory I both use the phone and on the chain of custody of form.


This prevents contamination of their equipment Group C or your solids and sludges. This is your soils. These are non-potable your solids sludges boots, whatever but what is interesting these samples are not tested as is rather these samples are extracted and then the extract is analyzed. Unfortunately, we have 50 states.


Every laboratory is doing their own protocol because at present time there are no USEPA approved extractions procedures each lab will use their own protocol therefore sometimes there's little consistency between labs. Andrew and I use a standard extraction procedure when we take samples. We send it to the laboratory and we insist they're going to use this protocol. The advantage of this is that when you split samples, each lab will use the same procedure. If you want a copy of this please contact So here's on a triage we have potable water we have brackish water we have the solids group a b and BC and their further separated hi PFAS low PFAS therefore the chemist will know exactly what to do and here's some actual samples. Samples 1 through 6 you look at sample number one it's potable water estimated PFAS concentration is low here's potable water load total dissolved solids but high PFAS generally it's due to AFFF here's brackish water greater than 100 brackish water greater than a thousand and look at soil see direct contract Jack with AFFF greater than 10,000 parts per trillion and here is a background sample taken. Let's say at the fence line that AFFF did not affect and you can see the concentration is low. We attach this also to the chain of custody form. Now. Let's talk about the caveat…in other words to put it bluntly the weak spots: your blanks and potable water.


We can look at parts per trillion. A part per trillion is a nanogram per liter for soils and commercial products. Sometimes we're looking at parts per million, which is a milligram per liter. If you look at the delta or the difference, it is 1 million fold and if you're saying to yourself right now, so what is a million fold difference – an example: if you were going to design a new face mask one thing you'd want to know is worth of diameter.


What is the length of the organism you're trying to filter out? One of the simplest ways of doing this is using a scanning electron microscope. And this is actually a photograph of a SEM and you can see the average length of this coronavirus. This Covid-19 is about a hundred and twenty nanometers. That's the average length a hundred and twenty nanometers if I take a hundred and twenty nanometers and x 1 million.


I get a hundred and twenty millimeters, which is about 4.7 inches to give you a perspective of what the difference is. This is a fishing lure with 3 treble hooks.


This is what 4.7 inches looks like compared to a virus and you imagine my analogy as SEM scanning electron microscope trying to see a virus and trying to look at This fishing lure using the same instrument. And obviously if you real world, you had a fishing lure like this what you would actually do is and in the you would use a micrometer. But again using my analogy in a scanning electron microscope you imagine putting this in a scanning like microscope moving it one millimeter.


Finding the length then moving it to millimeters moving at three millimeters on and on to a hundred and twenty times. The probability of error is unbelievable. And obviously again, you would use a caliper to actually measure the length of this therefore. My point is and again my analogy were using the same scanning electron microscope for a length of a virus and a fishing lure.


On PFAS analysis. We're using the same instrument tandem Mass Spec with a liquid chromatography for both parts per trillion in parts per million therefore the accuracy and just to give you an example now that we've gone from theory to these are actual samples Andrew and I were doing some sampling and imagine it again.


You are a judge you look at the sample a right here sample a and Has 422 parts per trillion total PFAS you say my goodness it is pretty contaminated. Look at the equipment blank. 432 look at the field blanks, obviously everything looks contaminated, but they only used a 1 mL sample all we did we call the laboratory up and we said we want it reanalyzed instead of a 1 mL sample.


We want a 150 mL sample and as is and what is interesting three days later, we get these results and you could see one from for 32 to 1 and the rest of these are below one part per trillion. Now, obviously this column here the green column in a court of law. This looks great this column here if your blanks are higher than your sample. I don't know many judges that are going to allow this in a court of law.


Also, the second caveat is their lack of real lack of range of linearity of PFAS again. Today's analytical techniques were designed for finished potable water. The instruments we’re using right now have a very good range accurate range between 5 parts per trillion and 1,000 parts per trillion anything below 5 and above.


1,000 is an estimate and laboratories in my opinion should put a J flag on each one of these to tell us all it is an estimate. Again, forget about theory these are actual samples and you and I we took samples and submitted to two of the top-tier laboratories in the United States. Both of these laboratories specialize in PFAS. Look at sample one.


First one is about a 1,000 parts per rayon this say laboratory be 362 3660 to look at sample number to about a thousand lab be about 4,000 look at sample 3 and here's the problem. Here's 36 million lab be 19 million sample for about 98 million and this is about a hundred and twelve million.


It's interesting. These were the closest we've seen the last one really epitomizes the problem right now with using a tandem Mass Spec sample a we have about 16 million parts per trillion. Look at lab be about 1.8 again. These are the exact same samples exact bottles exact preservatives everything.


As a please remember a good range of linearity PFAS between 5 and 1000 anything above a thousand be dubious about the other caveat that you everybody should be aware of if you look at test method EPA 530 7.14 PFAS. It's 18 molecules. Test method EPA 533 is 25 molecules. There's they overlap some of them they use the same molecules there.


Where we only have 29 unique molecules were testing for at the present time. Now, if you look at total PFAS versus total quantifiable PFAS (TQP). This pie chart gives you a perspective that little sliver in the middle.


That represents what we're testing at the right at the present time at the present time of the ten thousand molecules. We are testing for approximately three tenths of one percent now on the positive side, we're testing for the most toxic ones and so in a future, although there are 10,000 PFAS molecules. I think EPA is going to sort of separate.


The wheat from the chaff and say only these molecules. These are the most toxic ones these with these are the ones that we are going to really regulate the other caveat. Also when we have this little table here this little flow chart and you see that the whole family of PFAS at the present time. We are not testing for polymers because we're doing extraction.


It and here's a good example. Here's a fishing line a hundred percent fluorocarbon. The methanol right now used for extraction is not going to extract that. So, we're only looking at non-polymers these old pair boots. I don't know if it contains PFAS or not. Again, if the PFAS is ingrained into the fabric it is not going to extract it.


After the pandemic is done.


You're going to see and it's why it's so important to keep abreast of all the news on PFAS because I think SW 846 method 8327 direct-injection 83 28 solid-phase extraction are going to finally be finalized. DoD has their system ASTM has a 79 79 - 19 is oh, we'll be finalizing theirs. And the FDA will be finalizing theirs and I think after this pandemic is done you're going to see some good progress. Maybe this time next year.


So, here are my takeaways again for potable water you have we have good procedures for non-potable water for non-drinking soil sludge and brackish water assume every PFAS sample is going to come with some form of litigation. Number two sample properly use your field blanks. Your trip lines preservatives.


Do your proper sample containers per the state's jurisdiction if I'm doing soil sample in Vermont. I'm going to get on the Vermont website the Department of Environmental Conservation and look at their sampling protocol. If the State of Vermont does not have one then next you default to EPA’s protocol, but on my report, I'm going to note that so I remembered I did check Vermont's protocols. Number three: The lab is certified for PFAS for potable water per the state's jurisdiction.


And if I'm doing soil samples in Vermont, I'm going to ensure that the laboratory I use is certified for potable water in the state of Vermont. Number four: use a standard extraction procedure.


Every laboratory has their own in the problem with that the results are all over the place use a standard one again, please feel free to contact Andrew for that. Number five: triage samples ABC. Number 6: run your blanks first and think about it. You have a client and the analysis total is $30,000. If the blanks are all contaminated sometimes even with 250 mL sample. There's no reason to go any further because most of the other samples are not going to be admitted in a court of law if they're blanks are the same level of concentration as your soil samples.


Most likely to knock the admitted you're going to have to resample. Number 7: Know the analytical caveat…again anything less than five parts per trillion or greater than 1,000 parts per trillion is an estimate. Again, I want to thank Trihydro and Oklahoma State University for this privilege.


Thank you. Dr. Ede. Now. We're going to go ahead and switch over presenter screen to Andrew and he'll share insights with us regarding PFAS risk assessment as mentioned previously. We're holding questions until the very end. So if anything Dr. Ede covered sparked a question, please submit that in the attendee panel at any time Andrew is a board-certified toxicologist with over 20 years of experience in industry.


He regularly supports projects involving damage to the environment and human health by chemical agents including contaminants of emerging concerns such as peat moss Andrews others other areas of proficiency include risk-based remediation and side closure consumer product safety assessment chemical exposure and toxic chemical Regulatory Compliance. He is a member of various Professional Organizations.


And most recently the newly-formed Barnes and Thornburg LLC PFAS regulatory Coalition Andrew, I'll pass the presentation over to you.


Thank you, Amy for this introduction. And thank you. Dr. Ede for setting up the second part of this webinar.

We’ll continue the theme of data interpretation, but specifically as it relates to evaluating the potential impact on human health and environment. I would like to second some of the data quality challenges associated with laboratory results for PFAS.


But also would like to step back a little and talk about the key concepts both in risk assessment toxicology. So proper context given us to the data interpretation.


I will also like to spend a few minutes reciting some of the known harmful effects of PFAS on human health and also spend a few minutes looking at the general population exposure in us and globally then spend a few slides on the risk assessment concept.


And also have some potential thoughts on how to address the very complex issue of mixture toxicity for pieces counter.


Now I think that again one needs to step back every time there's a project like this and really ask a very simple question. So while we sampling well is this because they regulated let us requested of you that you collect samples or is it as Dr. Ede allocated this part of a some type of due diligence activity land transaction or something else.


I think the answer to the question is important because that divided B will not only determine the sampling design but also data interpretation need.


So then we come to a point that we got laboratory report and how do you make sense out of it? What do these numbers mean for different people’s compounds and then further on the line is the health issue. So if we have the house and drinking water, is the water safe?


And in context to that it's are there any limits that we can compare those results to and then what if multiple people as I lead present and we may not be testing for all of them. So ultimately really boils down to the senses. How much do we now do we know enough to probably conduct a risk assessment?


This slide is a little bit of an overlap with Dr. Ede’s, but it's an important one because it really underlines the difficulties that on the practical perspective because petitioner may faith.


So not only we have multiple exposure media and multiple methods currently in development. But each laboratory might have its own way of analyzing extracting presenting the results and this may not be immediately obvious to someone who's not familiar with performing around robbing or it's good sampling efforts that we did with dr. E8. So that's a flag of caution right there.


you'd indicated different methods not might have different unique piece has compounds available specifying those methods but the actual numbers May differ still depending on the discussion with your favorite laboratory. You may be able to give you results for more than 26 for example, and as Dr. Ede indicated also caution is required if your site is experiencing people's levels that are very low.


His those are the very high and that's that new the attitude issue doctor. He's indicated and then they dilution is very important. Sometimes this is not well communicated between the client and laboratory and that causes issue but overall really the objective here is to obtain the best possible.


Quality and data to support the exposure assessment and then the risk assessment. That's the objective. So another step back slide and this is something to do with you know, what does the risk assessment theories telling us?


Well this very simple slide is important to kind of think about is that essentially potential for Risk is an amalgamation or a combination the certain combination of level of exposure and toxicity. So neither exposure or toxicity by itself is necessarily equivalent to actual risk. It's only the combination of the two. So if you can keep that in mind as I present other content today.


And then looking at the toxicology aspects of the essentially theory of harm talking a little bit about the exposure is the very common expression paraphrased here is that dose makes the poison another concepts also to mention is the harm like this.


Has been caused by a chemical and risks which are known and harmful relations between chemicals and events.


And then it goes to say very nicely summarized by gazillion and all nineteen twelve thousand five that all other relations are possibilities that may never occur and then distinguishing risks from possibilities requires knowledge of causation so you can think about that little more so are PFAS harmful? the best line of evidence in terms of impacts of human health associated with the epidemiology people studies on actually populations that are have known exposure to PFAS and there's certain types of effects commonly found or associated and those involved a range of impacts of liver immune system endocrine system, And then development effects. I also I mention that those are unclear. Although we have indication that their impacts on laboratory


animals on the longer chain piece has compounds before on people's there's really no clear evidence and there's the uncertainties of confounding factors associated with the associations in population in in that talking a little bit about the dose makes the poison concept is that those associations were found in populations with blood levels of PCS much higher than normal populations and there's unaccounted factors. And then some of these responses may not have a clinical significance to them that is causing actual disease always and association.


Analysis are equivalent to cultivation tying it all in a little.


So looking at the possible mode of action and how PFAS get into a human body and what happens once they are inside. Well, unfortunately, we still learning about this and particularly human and most of the toxicological information concerns the longer chain that CA people are people's and in laboratory.


Laws, we do know however that PFAS have a propensity to bind the protein and there's certain molecular associations or impact related to regulation of enzymes hormones and lipids. There's also indication that the immune system might be impacted in terms of the antibody response.


And then cell membrane effects signaling in oxidative stress something.


I would like to point out in this graphic, which is an important exposure component of the messaging here is that most of the general population and most commonly is exposed to food exposure route no pathway and Includes food that might have been in contact with peace as containing packaging. So 3/4 of the overall those it comes from that and drinking water. This is only a small fraction of it. Another important aspect of the slide is the type of receptor the alpha ppar receptor, which is a protein and in humans the expression of discontent.


Seeing as it relates to PPA are activated and points is 10 times lower in laboratory animals. That's very important to keep in mind now on the theme of exposure.


Looking at say if you were to see the left-hand side of the slide when you have the heat map maps, it depicts the concentration of the longer chain to see a people's the sultanate and picograms a leader in the marine environment. This is a map of eastern Board of the US Atlantic levels.


And looking at the legend you can see the 1980s the Marine concentrations relatively low. Subsequently, the increased over the next 20 years to decades and then interestingly enough they decrease the current levels now. Okay, that's good.


Then if you can look at the middle section of the slide this depicts the various trends in concentration over time in different media so are because grams per millimeter cubed water picograms per liter and finally most interestingly in the top level lower trophic level receptor squid.


You can see also a decreasing trend about mid-2000s or so and then the bottom slide shows another line of evidence.


That is the aquatic discharges of PFAS in tons per year of the time again, you see a drop and just to make a note that this is this this critical time period is most likely associated with the voluntary production phase of implement…And I think going to the right hand side of the slide. This is really important because that shows the actual concentrations of beef as in human blood the top to show the Pecos before I concentrations as reported on nhanes recently. You can see there's 84 percent reduction in human blood concentrations of a time for the Pecos and 72.


LT follow and finally this is PFAS concentrations in serum in children in remote islands, which are dietary exposure to seafood so as consumer products and again, you can see significant reduction.


So there's evidence showing that indeed there is reduction concentrations now, transition into more of a quantitative risk assessment. This is a very good summary of the relative difference between actual US population exposure relative to the potential impact. So if you look quickly at in this case blood serum concentration associated with 10% effect level in the third column from the left.


This is the limit and then looking at the population actual exposures the nitrogen of safety measuring and thousands of fault now, so as I mentioned before well, we got to stand two levels exposure and toxicity on some of the longer chain.


compounds there are known and that he doesn't know and I think this graphic from Huet et al 2019 very nicely presents this issue. So what you see in front of you on the y-axis is the total extractable…flooring and potable water and nanograms per liter and two different time periods. 1992.


2016 on the histograms and why we can see that both before IP files were detected. Look at the


vast amount of potentially toxic PFAS compounds is present and drinking the water but this is something not regularly monitored and this talks a little bit to look for…we struggle with understanding the number of people as compounds possible in exposure medium. This is a quick summary.


Of the groundwater or drinking water limits established for various states. The way to read this chart is that anything in any states in blue has some type of limits that are equivalent to the EPA’s health advisories for people. Those in red are lower than that and those in green above it.


In addition, we put some stars on those states that have some type of promulgated actual plan on a draft activity. So this is in reference to build up in the asking. Okay. Well, there's a limit does this have compliance computation? This is also a good analogy in terms of what is one part per trillion.


This is from Michigan indicating that one drop in about 20 Olympic-sized swimming pools. That's the equivalent of that concentration. Just giving you an overview of the different jurisdictions to different advisory limits and just little bit of look under the hood.


…Use and certainty factors studies and the endpoints going to spend too much time on it.


A quick summary on the various aspects of performing risk assessment human health. The exposure assessment is attainable. You can measure various media. You can even look blood levels but ultimately the petition of the blood serum levels is difficult.


You do have values for the longer chain, and I believe additional toxicity testing is be formed and then there's that aspect of cumulative exposure and risk and I'll talk about that next. So this is the slide that probably most important one in terms of how do you handle eyes for mixture toxicity and taking the analogy from the environmental field? We have some good examples that we can draw.


So for example the toxicity equivalent factors something that we use for pH has already. Maybe we can apply the same thing to people. There's also the concept of Sentinel compound. So you pick one most toxic compounds in the like group something like 57 a dioxin and maybe you can equate the toxicity to the rest of the members in the mixture to that.


There's also type beat X component. You can also group by size or pahs again. You have the low molecular weight, high molecular weight groups and I believe because we also are looking at the short chain long chain things maybe we can derive toxicities for these types of groupings.


And then there's also the complex mixtures by themselves…maybe if we have a known product on the pivot side, we could test it and see what toxicity is. Also. We have another complex mixture environment. That's total petroleum hydrocarbons. We measure tph quite well and we provide interpretation of it. Maybe there's a way to interpret the total organic flooring the results of it.


So there's other equivalents pretty examples present that could be adopted conceptual bleeds. But in general right now, the add activity is assumed until we learn more about the specific interactions real quick note on the ecological acceptors. Unlike human being collected receptors are less understood.


In general specifically for PFAS and the ITRC presented very nice overview of this receptor group. You're going to spend too much time on it again, but in general we see that ecological receptors have low to moderate sensitivity except perhaps for some fish species and Wildlife acceptors, but we are limited.


By the fact that a lot of the toxicology confirmation is really meant for human beings not for wildlife receptors. And then some of the main complication is that really we need to add points that are significant to Loyola preceptors. So those associated with survival growth and reproduction.


I'll leave you with that one and well in summary, then there's there's just curious relations that we can share is that again, what is the distinguishing factor between actual risk and possibilities?


So we need to better understand Covid and are the effects found in admitted political studies sufficiently severe and now to be of clinical importance? That's important. Now there's data gaps for understanding and toxicity in humans. Yes. We do have animal studies and you're getting more but I think the link between the two is to be made in general has a population of disclosure.


They the difference between actual exposure to potential effects is quite large most of the time so although the quantitative risk assessment is possible on the toxicity endpoint side. You may find yourself with some data gaps.


And also what do we do about the toxicity of some of the short chain piece these compounds the animals metabolites and precursors in human bodies. And then how do we provide interpretation and management of the piecewise mixtures?


And typically the…compounds are not found individually but as mixtures So with this, I would like to thank you for attending this webinar and a me if you have any closing remarks, so there's any questions. Thank you.


Thank you Andrew. I think we have time maybe for one question that came through. Dr. Ede there was a question for you. How do you tell the lab if you anticipate high or low concentrations without knowing sampling results? 


Excellent question and so many times when you're doing sampling you have to do that background to find out what was that soil used for one-time. If this is a rural farm area and always used for farming the last 200 years, obviously, I would talk to laboratories.


Hey, listen, I doubt if this is going to be a group C PFAS, but if you have any indication at all, and that's why it’s so important on ASTM protocols Phase 1 and Phase 2 to talk to neighbors if any kind of fire suppressant was used or anything else that you believe has PFAS. Then you notify the laboratory, but sometimes it's a good question you are blind to the concentration initially.


Thank you. Dr. Ede.


Okay, we're approaching the end of our time together. If you have additional questions, please be sure to fill out our exit survey. There's a chance to request one-on-one time with us to discuss your interest further also note that if we didn't get to your questions during our hour together Andrew or Dr. Ede will be following up with you after the webinar. Please be aware that a recording of today's webinar will be delivered to your inbox tomorrow.


Thank you so much for joining us for today's webinar, and we hope you all have a great day and stay healthy.

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