1 00:00:00,750 --> 00:00:08,920 FRTR Presenter: some tweaks on pfas along the way. Risk assessment basics for human health. And it's Linda Grimes 2 00:00:09,130 --> 00:00:12,139 FRTR Presenter: from EPA, who will be our speaker. 3 00:00:12,600 --> 00:00:23,659 FRTR Presenter: And here's the little bio. It's an environmental engineer, environmental health scientist worked on site assessments, water wastewater work, air permits hazardous waste permits 4 00:00:24,110 --> 00:00:31,780 FRTR Presenter: PE license. Phd, focused on environmental health. She doesn't tell me where she went to school. I can't remember. 5 00:00:33,910 --> 00:00:36,380 FRTR Presenter: Yeah, don't we all 6 00:00:36,975 --> 00:00:45,439 FRTR Presenter: so she's the master of the regional screening levels. And I didn't know that until what I read this. So all right, there you go. 7 00:00:47,760 --> 00:01:03,130 FRTR Presenter: Yeah, it's funny. Most people used to know me for the ourselves. Now it's pfas. So there you go! So I'm in the inevitable position of keeping you from lunch, so I hope to get you to lunch on time, if not early. 8 00:01:04,740 --> 00:01:19,859 FRTR Presenter: Okay? So I was asked to give you some basics on risk assessment. I'm going to mainly be giving you a super fund perspective. But I will be discussing a little bit of some another program. 9 00:01:20,940 --> 00:01:23,509 FRTR Presenter: but in general, with risk assessment. 10 00:01:24,307 --> 00:01:32,640 FRTR Presenter: So well in superfund. First, st there's the planning, the scoping. You need to gather actual data before you can do a risk assessment. 11 00:01:33,228 --> 00:01:38,210 FRTR Presenter: And risk is a combination of toxicity and of exposure. 12 00:01:38,420 --> 00:01:42,429 FRTR Presenter: You can have toxicity, but if there's no exposure, there's not a risk 13 00:01:44,070 --> 00:01:58,049 FRTR Presenter: in superfund, we don't normally do the toxicity assessments, although sometimes there might be a site specific need exposure. Assessment is always going to be site specific in superfund. 14 00:01:58,990 --> 00:02:01,979 FRTR Presenter: and then you combine those. And now you get the risk. 15 00:02:03,210 --> 00:02:11,290 FRTR Presenter: So a toxicity assessment is an investigation into how toxic a contaminant may be to human health 16 00:02:11,400 --> 00:02:22,880 FRTR Presenter: or the hazard identification, the dose response relationship. I should note, I'm only going to be discussing human health. I don't do eco risk. 17 00:02:23,280 --> 00:02:33,800 FRTR Presenter: So with toxicity assessments. It's discussing what kind of harm are you going to be dealing with what illness or health effect may occur, and how much exposure can cause harm? 18 00:02:34,130 --> 00:02:41,680 FRTR Presenter: Maybe I should also mention within superfund. We hope to to stop the risk before you get to one of those. 19 00:02:43,500 --> 00:02:50,980 FRTR Presenter: There's really bad endpoints like death. So we're we're looking more of what are those long-term health effects? 20 00:02:51,620 --> 00:03:09,839 FRTR Presenter: So within toxicity we consider there to be 2 different categories of toxicity. There's non-carcinogenic chemicals. They are believed to act via threshold mechanism of action, which means that there's a level of exposure below which it's unlikely for an effect to occur. 21 00:03:10,100 --> 00:03:21,269 FRTR Presenter: And then there's carcinogenic chemicals. They're believed to act via non-threshold mechanism of action. But a risk may be the risk may be associated with any exposure level. 22 00:03:21,320 --> 00:03:31,199 FRTR Presenter: Of course I should also note many chemicals can cause both a carcinogenic effect and a non-carcinogenic effect. So we have to consider both. 23 00:03:32,780 --> 00:03:35,370 FRTR Presenter: Now with an exposure assessment 24 00:03:35,420 --> 00:03:49,330 FRTR Presenter: you are. You're looking at what are your exposure? Pathways and the main expo? The way we look at exposure is inhalation. Are you breathing something in? And it doesn't have to be necessarily volatile. It can be like an aerosol 25 00:03:50,850 --> 00:03:54,280 FRTR Presenter: oral. How somebody, you know you're eating it. 26 00:03:54,510 --> 00:03:59,049 FRTR Presenter: or dormal, you can come in contact with water or soil. 27 00:03:59,120 --> 00:04:00,180 FRTR Presenter: etc. 28 00:04:00,916 --> 00:04:07,160 FRTR Presenter: We consider the exposure duration. There's acute exposure. And so that's very short term. 29 00:04:08,819 --> 00:04:09,780 FRTR Presenter: There's 30 00:04:10,070 --> 00:04:23,499 FRTR Presenter: well acute is like kind of right away right short term longer term chronic and I will note there are different definitions of what these time spans are. 31 00:04:24,029 --> 00:04:32,569 FRTR Presenter: For example, atsdr and EPA consider chronic. There we look at them a little bit differently, but long term. 32 00:04:33,650 --> 00:04:40,279 FRTR Presenter: Now with the potential exposed population again within superfund, this is definitely going to be site specific. 33 00:04:40,360 --> 00:04:42,152 FRTR Presenter: So, for example, 34 00:04:43,430 --> 00:04:50,850 FRTR Presenter: if you're looking at an industrial area, you're going to be considering workers. And hopefully, those workers will all be adults. 35 00:04:51,711 --> 00:05:00,989 FRTR Presenter: Whereas residential you're going to be considering, you know more children, the elderly you might be considering pregnant women. What are those? 36 00:05:01,090 --> 00:05:03,034 FRTR Presenter: What are your more? 37 00:05:04,050 --> 00:05:09,699 FRTR Presenter: In other words, we want to look at everyone but someone. Some of them are more at risk. 38 00:05:12,496 --> 00:05:19,339 FRTR Presenter: An exposure is quantified as the amount of the agent available at the exchange boundaries. 39 00:05:20,420 --> 00:05:23,519 FRTR Presenter: How much are you ingesting? How much are you breathing in? 40 00:05:23,870 --> 00:05:28,439 FRTR Presenter: And also again going back to who is being exposed. 41 00:05:28,550 --> 00:05:32,020 FRTR Presenter: and how much of the contaminants are they being exposed to? 42 00:05:34,563 --> 00:05:42,279 FRTR Presenter: So again, with the I probably am reiterating a little bit, but with the exposure pat assessment. 43 00:05:42,440 --> 00:05:55,619 FRTR Presenter: particularly in superfund. We're looking at all these various pathways. So again, inhalation, the gases, the vapor, airborne particles, including soil. So if you're playing in the soil, and you know it can become airborne 44 00:05:56,470 --> 00:06:00,509 FRTR Presenter: ingestion. Be it the soil, the water, your food 45 00:06:00,600 --> 00:06:02,430 FRTR Presenter: and dermal contact. 46 00:06:06,700 --> 00:06:11,220 FRTR Presenter: So we're looking at site, specific exposure pathways. 47 00:06:12,330 --> 00:06:13,340 FRTR Presenter: So 48 00:06:13,480 --> 00:06:15,670 FRTR Presenter: you may be looking at oops. 49 00:06:16,090 --> 00:06:27,980 FRTR Presenter: Sorry. So they're sort of standard assumptions made. But then you also have to look at things site specifically. And then what are the current and future land use for your area? 50 00:06:28,770 --> 00:06:35,689 FRTR Presenter: And we look at the reasonable maximum exposure. So the high end exposure to the sensitive populations 51 00:06:35,870 --> 00:06:38,880 FRTR Presenter: to be protective of vulnerable groups in the community. 52 00:06:39,030 --> 00:06:58,520 FRTR Presenter: So often we're looking at children because we can. They're more sensitive than an adult, but by reasonable maximum exposure, it should be noted again, the word reasonable is important here. So if you're familiar with the there's an eating disorder known as pica. People who eat 53 00:07:01,540 --> 00:07:17,520 FRTR Presenter: There are populations, for example, of women who are known to eat clay and we don't look at those. That's not really. I mean, I guess if you had an entire population we would. But that's not really considered to be reasonable exposure. 54 00:07:19,207 --> 00:07:25,649 FRTR Presenter: Okay. And then, just to get into, give some examples to get into the specifics with superfund 55 00:07:26,187 --> 00:07:36,009 FRTR Presenter: for example, generally especially for residential, not for, like commercial. The default receptor is going to be a child because they're more sensitive than an adult. 56 00:07:36,940 --> 00:07:45,580 FRTR Presenter: So, for example, some default, exposure, assumptions are a body mass of 15 kg, exposure, duration of 6 years. 57 00:07:46,161 --> 00:08:06,399 FRTR Presenter: We assume that the person goes on vacation, in other words, away from home for 2 weeks out of the year, so they're exposed for 350 days a year. And then there are other exposure parameters, and these all come from, like most of our parameters, come from EPA's exposure factors, handbook. 58 00:08:08,750 --> 00:08:22,510 FRTR Presenter: Now, risk. So that's integrating the data from from everything you've done, from from the data gathering, from the toxicity assessments and from the exposure assessments. 59 00:08:22,790 --> 00:08:24,110 FRTR Presenter: And so 60 00:08:24,380 --> 00:08:33,300 FRTR Presenter: you, you combine them all, and you evaluate the uncertainty. And then that data, and you summarize everything to consider the overall health risk 61 00:08:33,310 --> 00:08:35,320 FRTR Presenter: in a number or estimate 62 00:08:36,060 --> 00:08:40,089 FRTR Presenter: and different methods are used for cancer versus non-cancer. 63 00:08:40,931 --> 00:08:51,880 FRTR Presenter: And again, you're considering you consider all the pathways. But maybe one is creating more of a risk than another, and which contaminants are causing these health risks. 64 00:08:55,260 --> 00:09:11,900 FRTR Presenter: So again, super fun in calculating risk for cancer, we're usually using a target risk value somewhere between 10 to the minus 6 and 10 to the minus 4 as being considered acceptable. Depending upon the situation 65 00:09:12,570 --> 00:09:20,110 FRTR Presenter: for non-cancer risk. We're using a hazard index and normally greater than one indicates a potential risk. 66 00:09:20,649 --> 00:09:24,720 FRTR Presenter: It does not mean with all these numbers, it doesn't mean there's 67 00:09:24,810 --> 00:09:28,910 FRTR Presenter: somebody's going to get a health effect. If we're just looking at 68 00:09:29,260 --> 00:09:32,090 FRTR Presenter: an acceptable or non-acceptable risk. 69 00:09:32,490 --> 00:09:38,307 FRTR Presenter: and the risk is calculated for all contaminants present and for all media they are present in 70 00:09:38,730 --> 00:09:42,679 FRTR Presenter: that's well for superfund that's related to the spill or release. 71 00:09:44,790 --> 00:09:46,720 FRTR Presenter: So for cancer risk. 72 00:09:46,730 --> 00:09:50,480 FRTR Presenter: it's the sum of the individual chemical cancer risks. 73 00:09:50,941 --> 00:09:56,279 FRTR Presenter: And again, we're looking at 10 to the minus 6 or 10 to the minus 4 for being acceptable. 74 00:09:56,570 --> 00:10:09,640 FRTR Presenter: And so just thinking about pfas at the moment, this would be, the total cancer risk would be pfoa and pfas combined, because those are the only 2 pfas that at the moment we have a cancer value for. 75 00:10:10,690 --> 00:10:17,740 FRTR Presenter: And I should also note, those are both ingestion cancer values. We don't have inhalation, toxicity for any pfas at the moment. 76 00:10:19,930 --> 00:10:21,919 FRTR Presenter: Now, a hazard index 77 00:10:22,502 --> 00:10:28,510 FRTR Presenter: is so the the hazard index is the sum of the hazard quotients. 78 00:10:28,630 --> 00:10:33,760 FRTR Presenter: Now a hazard quotient is the exposure divided by a reference dose 79 00:10:35,410 --> 00:10:39,259 FRTR Presenter: And then again, you sum those to get the hazard index. 80 00:10:40,990 --> 00:10:49,810 FRTR Presenter: now again using pfas as an example. So right now in superfund, the hazard index for a pfas would be 81 00:10:49,920 --> 00:10:55,190 FRTR Presenter: combining the hazard quotients for all the different pfas for which we have 82 00:10:55,230 --> 00:10:57,130 FRTR Presenter: a toxicity value. 83 00:10:58,990 --> 00:11:05,090 FRTR Presenter: we don't have toxicity values for a lot of pfas, but you can consider that like within your uncertainty. 84 00:11:06,280 --> 00:11:14,380 FRTR Presenter: but you can never forget that there there are other contaminants that, in fact exist besides pfas. So, in other words. 85 00:11:14,400 --> 00:11:17,709 FRTR Presenter: If you have a chrome plating site 86 00:11:17,780 --> 00:11:20,550 FRTR Presenter: and you find that there's pfas there. Well. 87 00:11:20,610 --> 00:11:24,739 FRTR Presenter: then, you probably also have chromium which you need to be considering the risk of 88 00:11:27,787 --> 00:11:35,079 FRTR Presenter: now for the Circle. Hq. I thought I'd go into a little bit more specifics here. So, for example, the 89 00:11:35,310 --> 00:11:52,309 FRTR Presenter: for the Circle, Hq for the tap water screening level. When we're computing this, this is based on both the ingestion of tap water, the inhalation of tap water. So think about like when you're in the shower. If there are volatiles in the drinking, water can become airborne, and you can be breathing that in 90 00:11:53,051 --> 00:11:55,780 FRTR Presenter: also the dermal contact with the tap water. 91 00:11:57,240 --> 00:12:03,009 FRTR Presenter: Now for pfas, specifically, none of these, again, have inhalation toxicity values. 92 00:12:03,080 --> 00:12:21,570 FRTR Presenter: So currently, that's not going to be combined in there. Now, when we do our calculations, several of the pfas do, in fact, have a dermal component, but generally it's pretty much insignificant compared to the ingestion, and the dermals based on 93 00:12:23,050 --> 00:12:25,270 FRTR Presenter: physicochemical properties. 94 00:12:26,510 --> 00:12:27,720 FRTR Presenter: And there's 95 00:12:28,940 --> 00:12:31,529 FRTR Presenter: there's guidance on how we calculate that 96 00:12:32,890 --> 00:12:33,850 FRTR Presenter: so 97 00:12:34,100 --> 00:12:47,169 FRTR Presenter: totally expecting you to memorize all these equations. I'm about to show you, but I just kind of wanted to show it to you as an example and of note. All these equations I'm about to show you can be found on our regional screening levels 98 00:12:47,310 --> 00:12:48,630 FRTR Presenter: website. 99 00:12:48,720 --> 00:12:53,580 FRTR Presenter: But this is just to show you that again, as an example with tap water. 100 00:12:54,110 --> 00:12:58,500 FRTR Presenter: it's a combination of the ingestion, the inhalation and the dermal. 101 00:12:58,880 --> 00:13:01,310 FRTR Presenter: And we do this really weird 102 00:13:02,070 --> 00:13:06,759 FRTR Presenter: inverse of the inverses. And I don't honestly remember why we do that. 103 00:13:06,940 --> 00:13:07,600 FRTR Presenter: And 104 00:13:08,600 --> 00:13:12,329 FRTR Presenter: so for the tap water screen level for ingestion. 105 00:13:13,354 --> 00:13:27,450 FRTR Presenter: Again, we're considering that reference dose, and we're looking. And then the rest of what is in here is those exposure parameters. So, in other words, your averaging time for exposure, your exposure, duration. 106 00:13:27,490 --> 00:13:37,779 FRTR Presenter: the the body mass for a child, which is 15 kg, and the child is assumed to ingest 0 point 7 8 liters of water per day. 107 00:13:39,642 --> 00:13:49,599 FRTR Presenter: This is a crazy set of equations. But again, this is how we look at the the Dermal exposure for tap water. 108 00:13:50,350 --> 00:13:55,529 FRTR Presenter: Again, you can find all these on the website. And really, if you want to get into the the. 109 00:13:55,850 --> 00:13:58,900 FRTR Presenter: the, the minutia of how we compute all this 110 00:14:01,973 --> 00:14:09,650 FRTR Presenter: and just to show you an example, for the Pfas for the Rsls. And I wanted to compare them to the Mcls. 111 00:14:10,331 --> 00:14:20,640 FRTR Presenter: You can see the reference doses that for all these pfas, and they vary quite a bit. But you'll notice only Pfo and Pfos have cancer values. 112 00:14:21,020 --> 00:14:22,493 FRTR Presenter: And so 113 00:14:23,330 --> 00:14:24,520 FRTR Presenter: with the 114 00:14:25,010 --> 00:14:27,800 FRTR Presenter: when you're looking at risk 115 00:14:27,940 --> 00:14:32,239 FRTR Presenter: because you need to combine the different Hqs 116 00:14:32,350 --> 00:14:40,900 FRTR Presenter: to get your hazard index. If so if you have a very rare site where you have one and only one contaminant there. 117 00:14:40,980 --> 00:14:46,759 FRTR Presenter: your Hq. Is equal to your HI. In other words, your hazard index is based on that one contaminant. 118 00:14:47,740 --> 00:14:51,440 FRTR Presenter: whereas if you have multiple ones, you have to combine those Hq's. 119 00:14:51,670 --> 00:14:58,250 FRTR Presenter: So for simplicity to as for ease of use with the regional screening levels. 120 00:14:58,918 --> 00:15:16,010 FRTR Presenter: We produce tables at an Hq. Of one which, again, is representative of, if you have one contaminant, we also produce tables with an Hq. Of 0 point 1 that is based on the theory of you have a site that has 10 contaminants. 121 00:15:16,080 --> 00:15:25,049 FRTR Presenter: So in other words, you'd want a 10th of your hazard quotient per contaminant. You combine them. Now you have a hazard index of one. 122 00:15:25,210 --> 00:15:26,660 FRTR Presenter: That's the theory. 123 00:15:26,830 --> 00:15:33,980 FRTR Presenter: Are the regional screening levels are just a tool. They're not guidance. They're not regulatory. They're not 124 00:15:34,240 --> 00:15:35,730 FRTR Presenter: cleanup levels. 125 00:15:35,770 --> 00:15:48,360 FRTR Presenter: But these are just tools. And these can kind of help, quick, easy use when you're investigating a site. And it can kind of show you how the screening levels you need to go lower if you have multiple contaminants. 126 00:15:50,036 --> 00:15:57,759 FRTR Presenter: And just to also kind of can show you how the screen levels are based solely on a risk calculation 127 00:15:57,940 --> 00:15:59,960 FRTR Presenter: we don't consider. 128 00:16:00,060 --> 00:16:03,837 FRTR Presenter: We only consider the toxicity and the exposure. 129 00:16:04,320 --> 00:16:28,529 FRTR Presenter: we don't consider, for example, the fact that a screen level may be below a detection limit, and there's absolutely no way to, you know. Get to that number. It's just a calculation. And so that's 1 of the reasons I wanted to compare them to the Mcl. So you can see how there is a difference between these numbers, because the Mcls are regulatory and they have to consider. You know. 130 00:16:28,600 --> 00:16:31,299 FRTR Presenter: things like, can you detect it at that level. 131 00:16:35,990 --> 00:16:39,919 FRTR Presenter: now, I kind of wagered. There'd be some people who perhaps 132 00:16:40,100 --> 00:16:42,180 FRTR Presenter: 1st heard of a hazard index 133 00:16:42,230 --> 00:16:49,929 FRTR Presenter: when EPA's office of water produced an Mcl. For pfas the pfas HI. Mcl 134 00:16:50,305 --> 00:16:58,529 FRTR Presenter: so I thought it'd be kind of a an interesting, I thought, for those who are not familiar with the hazard index. This would be a good way to kind of 135 00:16:58,600 --> 00:17:12,909 FRTR Presenter: explain a little bit more about a hazard index to compare the Circle Hazard index to the the Sidwa Hazard index. Just to kind of show you how things can change, depending upon your program, your assumptions and things like that. 136 00:17:14,180 --> 00:17:24,540 FRTR Presenter: So both of these, the the Circula and the Sidwa Hazard index. They're both based on that same overall concept of combining 137 00:17:24,610 --> 00:17:31,650 FRTR Presenter: the hazard quotients from different compounds into a total hazard index, a total risk, calculation. 138 00:17:31,880 --> 00:17:42,750 FRTR Presenter: The Cidwa excuse me, the Safe Drinking Water Act. Cigwa is based on Cidwa regulations. The Circle Hi is based on circle regulations, and it's based on our guidance. 139 00:17:43,670 --> 00:17:46,250 FRTR Presenter: Neither is wrong. They're just different. 140 00:17:48,136 --> 00:17:56,419 FRTR Presenter: So with Sibwa, their HI is based on 4 pfas, they're based on Pf, and a Pfhxs. Pfbs. 141 00:17:56,450 --> 00:17:59,999 FRTR Presenter: an Hfpo dimer, which some people call Gen. X. 142 00:18:01,813 --> 00:18:11,550 FRTR Presenter: It uses a Sidwa health based water concentration for the ratio, and these are regulatory, so they can only change with regulatory updates. 143 00:18:12,140 --> 00:18:16,889 FRTR Presenter: Now, the Cercla Hi is based on all pfas found at a site 144 00:18:17,020 --> 00:18:21,130 FRTR Presenter: plus any other contaminant non pfas contaminants found at a site 145 00:18:21,915 --> 00:18:25,499 FRTR Presenter: or at least those that which we have a toxicity value. 146 00:18:27,112 --> 00:18:33,989 FRTR Presenter: We're, however, with Cercla. We're only looking at the exposure that's related to a spill or a release. 147 00:18:34,820 --> 00:18:50,309 FRTR Presenter: and our values will be updated when we get new toxicity information. So, for example, a couple months ago, I guess now, the EPA's office of research and developed released a new iris value for Pfda. 148 00:18:50,630 --> 00:18:55,890 FRTR Presenter: So when we update the regional screen levels in a couple of weeks 149 00:18:56,080 --> 00:18:57,959 FRTR Presenter: it'll be put in there. 150 00:18:58,778 --> 00:19:06,230 FRTR Presenter: We are awaiting Iris assessments on Pf. And A and pfa checks. When we get the final value we'll be considering those 151 00:19:09,765 --> 00:19:14,600 FRTR Presenter: again. So the Circle Hi is based on what we refer to as rags 152 00:19:14,620 --> 00:19:17,219 FRTR Presenter: risk assessment, guidance for superfund. 153 00:19:17,330 --> 00:19:24,020 FRTR Presenter: I've always considered the acronym rags to be somewhat funny. But anyway, so we use those equations. 154 00:19:24,512 --> 00:19:32,569 FRTR Presenter: And for the sake of comparison, I've sort of adjusted the equation to allow easier comparison to the Sidba equations. 155 00:19:33,549 --> 00:19:41,689 FRTR Presenter: And what I'm about to present again, it ignores non pfas contaminants that may be present, and also should be used in a calculation. 156 00:19:44,170 --> 00:19:46,299 FRTR Presenter: So the circle. HI. 157 00:19:46,400 --> 00:19:54,620 FRTR Presenter: This is long again. It's the exposure dividing it by the screening level to give that ratio for your hazard. Quotient. 158 00:19:58,722 --> 00:20:01,970 FRTR Presenter: Okay, so these are the the 159 00:20:02,070 --> 00:20:04,859 FRTR Presenter: reference doses for the various pfas. 160 00:20:06,310 --> 00:20:10,169 FRTR Presenter: they all have the exact same drinking water, intake. 161 00:20:10,270 --> 00:20:12,299 FRTR Presenter: body mass 162 00:20:12,970 --> 00:20:14,120 FRTR Presenter: number 163 00:20:14,743 --> 00:20:18,780 FRTR Presenter: so you're. And then the Rsc. Is a relative source 164 00:20:18,800 --> 00:20:22,610 FRTR Presenter: contribution. Just hang on to these for a minute, because 165 00:20:22,950 --> 00:20:26,769 FRTR Presenter: once I show the Sidwell, I'll kind of explain why I'm showing them for Circle F. 166 00:20:27,190 --> 00:20:31,530 FRTR Presenter: But for Cercla the Rsc. Is always one. 167 00:20:32,120 --> 00:20:35,740 FRTR Presenter: because we are only concerned about a spill or release. 168 00:20:36,620 --> 00:20:49,689 FRTR Presenter: and then I have an asterisk by Pfo and Pfos. Just as a reminder, those have a cancer value. So while they're part of the Hi, you also have to consider the cancer value. 169 00:20:51,480 --> 00:20:56,400 FRTR Presenter: Now the Sidwa Hi is again based on only 4 pfas 170 00:20:57,469 --> 00:21:04,320 FRTR Presenter: and their health-based water concentration is the Rfd. Divided by the drinking water intake. 171 00:21:04,410 --> 00:21:09,860 FRTR Presenter: divided by the body mass and then multiplied by that relative source contribution. 172 00:21:12,800 --> 00:21:14,020 FRTR Presenter: So 173 00:21:15,550 --> 00:21:17,530 FRTR Presenter: they're using now. 174 00:21:19,120 --> 00:21:22,089 FRTR Presenter: with one exception. For so for 3 of these 175 00:21:22,280 --> 00:21:28,089 FRTR Presenter: we use the same toxicity value as offset water does for Pfh excess. 176 00:21:28,230 --> 00:21:37,834 FRTR Presenter: We're both using the Atsdr minimal risk level. But office of water has applied an extra uncertainty factor. 177 00:21:38,510 --> 00:21:40,729 FRTR Presenter: that has to do with 178 00:21:41,550 --> 00:21:43,540 FRTR Presenter: chronic versus subchronic. 179 00:21:43,590 --> 00:21:49,730 FRTR Presenter: Olem has not done that. So we we have a slightly different value because we haven't applied that value. 180 00:21:51,900 --> 00:21:58,469 FRTR Presenter: and you'll note that they use. They have different drinking water intakes and body mass numbers 181 00:21:59,148 --> 00:22:02,679 FRTR Presenter: depending upon the the different pfas. 182 00:22:04,350 --> 00:22:12,850 FRTR Presenter: I think I have a slide explaining why in here they use a relative source contribution of point 2. So what that means is 183 00:22:13,260 --> 00:22:17,009 FRTR Presenter: when it comes to. For example, pf, and A, they're saying. 184 00:22:17,210 --> 00:22:24,829 FRTR Presenter: in order to stay below a risk level, 20% of your Pf. And a daily intake can come from drinking water 185 00:22:25,090 --> 00:22:30,210 FRTR Presenter: because another 8, but because they're saying 80% can come from 186 00:22:30,530 --> 00:22:33,679 FRTR Presenter: wherever. So maybe that's 187 00:22:33,720 --> 00:22:38,950 FRTR Presenter: the carpet in, you know, in the house you live in. Maybe that is. 188 00:22:39,030 --> 00:22:41,369 FRTR Presenter: I don't know. The food you buy. 189 00:22:42,060 --> 00:22:54,390 FRTR Presenter: This is compares to Circula, where again, we're only looking at the Spiller release. So we don't consider the carpet in your house, unless the carpet is somehow or another related to the release into the environment. 190 00:22:55,880 --> 00:22:57,909 FRTR Presenter: and they use different. 191 00:22:58,771 --> 00:23:02,219 FRTR Presenter: So I've got the different Hbwcs on here. 192 00:23:07,090 --> 00:23:10,840 FRTR Presenter: I think this is slightly out of place. But this is just sort of a 193 00:23:14,240 --> 00:23:21,724 FRTR Presenter: sorry I don't. I thought I'd rearrange these a little bit. I I'd put this in here just as a note that 194 00:23:22,590 --> 00:23:43,690 FRTR Presenter: states. So if you have a site, you have to consider both Federal and may need to consider the State and the States have different. They have their own water levels, right? They use sometimes they're using different toxicity values, and they also use different exposure parameters. So in other words, the States may have different risk levels from EPA 195 00:23:45,550 --> 00:23:49,359 FRTR Presenter: They have different regulations. They have different priorities. 196 00:23:49,480 --> 00:23:51,380 FRTR Presenter: They look at things differently. 197 00:23:55,890 --> 00:24:00,750 FRTR Presenter: Is this the I'm sorry, Jean, is this, I don't think this is the updated one. 198 00:24:01,390 --> 00:24:16,940 FRTR Presenter: If you want to give me a minute. I can try. But that should have been. It might take a second. It's okay. I apologize. I had updated this just a little bit to put in a couple of explanatory things, and this doesn't appear to be it. 199 00:24:18,060 --> 00:24:21,949 FRTR Presenter: I'm gonna see? Give us 1 min to see if Gene can find it. 200 00:24:33,970 --> 00:24:48,430 FRTR Presenter: I apologize. I had when I was sending this through review, I got some good questions. And I'm like, Okay, these are good questions. And if somebody at EPA has this question, then somebody else might have a question, and so I inserted a couple of extra things into the slides. 201 00:24:56,610 --> 00:25:08,789 FRTR Presenter: And so, Linda, it might take us about a minute or 2 to pull that up, because I've got to sync over are there potentially questions in the room that we could take while we're doing that because I do have some online. 202 00:25:12,020 --> 00:25:35,260 FRTR Presenter: There aren't any in the room. I might take a question or 2 here online while I'm looking for that. And so, Linda, as I'm looking through here, there was a question that came through asking, what would a Sdwa so safe drinking Water Act versus Cercla hazard index difference, be 203 00:25:37,230 --> 00:25:44,330 FRTR Presenter: they could differ quite a bit. So, in other words, like, in other words, would the numbers come out differently? 204 00:25:45,920 --> 00:25:48,019 FRTR Presenter: if that's what the question is. 205 00:25:48,880 --> 00:25:49,980 FRTR Presenter: So 206 00:25:50,010 --> 00:25:52,269 FRTR Presenter: if you have. 207 00:25:53,040 --> 00:25:54,349 FRTR Presenter: let's see. 208 00:25:55,179 --> 00:25:59,439 FRTR Presenter: In other words, if you have a site that has 209 00:26:00,489 --> 00:26:03,730 FRTR Presenter: these 4 pfas, and only these 4 pfas 210 00:26:05,156 --> 00:26:06,550 FRTR Presenter: you actually. 211 00:26:07,630 --> 00:26:12,189 FRTR Presenter: then the Circle Hi and the Sidba Hi are actually still going to differ 212 00:26:12,260 --> 00:26:15,490 FRTR Presenter: because we use different exposure parameters. 213 00:26:17,739 --> 00:26:24,780 FRTR Presenter: and I can't tell you what the numbers would be just like off the top of my head. But, for example, if you had. 214 00:26:24,790 --> 00:26:29,634 FRTR Presenter: if you had a site with these 4 pfas, but then you also had 215 00:26:30,220 --> 00:26:32,650 FRTR Presenter: you know. Pf, HXA 216 00:26:33,430 --> 00:26:39,170 FRTR Presenter: super fun. We use a toxicity. We have an Irish toxicity value for that. So 217 00:26:39,890 --> 00:26:47,460 FRTR Presenter: so, in other words, that would go into the hi used for Circula. But it doesn't go into the hi used for Sidwa. 218 00:26:47,510 --> 00:26:48,780 FRTR Presenter: because 219 00:26:49,470 --> 00:26:52,110 FRTR Presenter: the regulation is based on these 4. 220 00:26:53,821 --> 00:27:15,910 FRTR Presenter: So it, for example, I heard somebody in here. Basically, I don't remember who it was, but somebody complaining about the how the super how the the regulations regarding pfas keep changing, and that's irritating them. And I feel your pain. I. We update the regional screening levels every 6 months, and I've heard 221 00:27:15,910 --> 00:27:33,600 FRTR Presenter: numerous people, both outside EPA and people within EPA, who complain. We update them too often. So we have to find a balance between keeping them up to date with new information. But like not changing them so often that you can't get anything done. 222 00:27:34,910 --> 00:27:35,990 FRTR Presenter: so yeah. 223 00:27:38,470 --> 00:28:03,939 FRTR Presenter: okay, I see another question that came in online. And this one is asking. They just make an observation that traditionally pfas have been considered not to be able to penetrate human skin because they're ionized. And that's why dermal risks have been considered negligible. But they quoted a study from 2024 that showed that particularly smaller pfas can seem to get through the skin barrier. 224 00:28:04,450 --> 00:28:17,629 FRTR Presenter: They were just wondering if EPA is aware or going to look into that research or research pfas, dermal exposures and then adjust the dermal absorption equations for pfas compounds to account for this. 225 00:28:18,170 --> 00:28:27,979 FRTR Presenter: That's a really good question. So we look at Dermal we consider Dermal based on some physical chemical properties. 226 00:28:28,140 --> 00:28:37,000 FRTR Presenter: and I could not tell you right off the bat which ones they are. But basically, if you. If these physical chemical properties 227 00:28:37,040 --> 00:28:49,869 FRTR Presenter: have a ratio or a product or something at this number, we consider it within. We call it the effective predictive domain. I think it's 1 and one of our many lovely acronyms. 228 00:28:50,530 --> 00:28:51,670 FRTR Presenter: So 229 00:28:52,380 --> 00:28:56,140 FRTR Presenter: which is a long way of saying that we're not. 230 00:28:56,840 --> 00:29:08,380 FRTR Presenter: We don't. We don't look at dermal exposure like, Okay, somebody came up with the new research, and it shows that things are absorbed. Dermally, we're looking at the physical chemical properties. So 231 00:29:08,460 --> 00:29:21,020 FRTR Presenter: if the the important physical chemical properties for any chemical pfas or not. If those update that can change whether or not we're considering the dermal absorption. So 232 00:29:21,490 --> 00:29:29,699 FRTR Presenter: I am not denying at all that the science is evolving on dermal exposure to pfas. 233 00:29:29,960 --> 00:29:35,259 FRTR Presenter: Right now, we don't have like specific ways of looking at it. Apart from 234 00:29:35,660 --> 00:29:36,933 FRTR Presenter: with these. 235 00:29:38,120 --> 00:29:40,469 FRTR Presenter: these equations that we use. 236 00:29:43,413 --> 00:29:47,380 FRTR Presenter: Okay? And a similar question. 237 00:29:47,759 --> 00:30:05,009 FRTR Presenter: or sorry, a related statement. Somebody chimed in and said that the Rsc is the current main difference. I think this is getting back to an earlier question that you were answering, and they noted that there might be some changes. Once the Iris Tox value is finalized. 238 00:30:05,310 --> 00:30:09,350 FRTR Presenter: I don't know if you have any thoughts on that observation. The Rsc. 239 00:30:09,560 --> 00:30:14,600 FRTR Presenter: So the Rsc. Is a relative source contribution that is based on 240 00:30:16,160 --> 00:30:19,440 FRTR Presenter: the the office of water looks at 241 00:30:19,870 --> 00:30:20,680 FRTR Presenter: like 242 00:30:21,210 --> 00:30:23,849 FRTR Presenter: what is your exposure 243 00:30:23,900 --> 00:30:41,949 FRTR Presenter: likely to be? And I'm not in that program, so I can't. I'm not an expert on it, but superfund doesn't use it at all, because again, we're looking at the spill or release. So the relative source contribution is sort of based on the idea of. There are other sources of pfas out there. 244 00:30:43,890 --> 00:30:50,379 FRTR Presenter: That should. I don't think that would change with an iris update, unless the 245 00:30:50,450 --> 00:30:52,349 FRTR Presenter: the Irish value 246 00:30:53,720 --> 00:30:59,750 FRTR Presenter: well within Irish, they might provide some information in terms of 247 00:30:59,860 --> 00:31:02,050 FRTR Presenter: how people might be exposed. 248 00:31:02,250 --> 00:31:08,289 FRTR Presenter: however, because the Sidwa Hi is based on a regulation. 249 00:31:08,390 --> 00:31:09,739 FRTR Presenter: You have to 250 00:31:10,020 --> 00:31:14,460 FRTR Presenter: update the regulation in order to update the numbers within it. 251 00:31:16,450 --> 00:31:36,670 FRTR Presenter: Okay, this is the one that we got from the email. And I believe it's the same deck. But I just wanted to put that there. And as you're clicking through that, there was another question, when will the super fund chemical data, matrix or skittable be updated with the Mcls for and get ready 252 00:31:37,110 --> 00:31:38,230 FRTR Presenter: pfoa. 253 00:31:38,290 --> 00:31:39,480 FRTR Presenter: pfas. 254 00:31:39,650 --> 00:31:46,550 FRTR Presenter: PFHX, SPFN, a. And HFPO, hyphen, DA. 255 00:31:47,217 --> 00:31:51,120 FRTR Presenter: Yeah. So skiddom, as we call it. 256 00:31:51,330 --> 00:31:54,059 FRTR Presenter: I. Oh, gosh! So 257 00:31:54,070 --> 00:32:12,200 FRTR Presenter: we the update dates for Skidm. We have a window. That is because for those of you who are not familiar with it, scidum is used specifically for scoring a site within the hazard ranking system to determine whether or not it's eligible to become a superfund site 258 00:32:12,910 --> 00:32:25,630 FRTR Presenter: because of the public comment window when we proposed an Npl site. And then, when we finalize the Npl site, we have a window within which we do not updates. Well, in other words. 259 00:32:25,690 --> 00:32:28,410 FRTR Presenter: there's a window. When we update Skiddom. 260 00:32:28,832 --> 00:32:34,717 FRTR Presenter: We don't update it during public comment periods, because that would just screw everyone up. 261 00:32:35,220 --> 00:32:53,059 FRTR Presenter: I I want to say the next update for skin will be towards the end of the year. But please don't hold me to that. It generally. This is one of those things when the contractor tells me when we can do it, but I will say we are preparing for it, and they are our contractors already working on it with the information. 262 00:32:58,130 --> 00:32:59,140 FRTR Presenter: let me see. 263 00:33:02,390 --> 00:33:03,290 FRTR Presenter: Yes. 264 00:33:05,170 --> 00:33:13,090 FRTR Presenter: okay. So I'm sorry for the sort of the little mess up I wanted to get to these. Some other things. 265 00:33:13,570 --> 00:33:15,849 FRTR Presenter: okay. So with cercla. 266 00:33:16,480 --> 00:33:24,410 FRTR Presenter: I was showing you the equations for tap water for non-cancer. So it's a similar concept for cancer. 267 00:33:25,210 --> 00:33:26,620 FRTR Presenter: similar 268 00:33:26,790 --> 00:33:32,690 FRTR Presenter: type concept for soil. You're going to have very different equations. But the concept is the same. 269 00:33:33,110 --> 00:33:36,999 FRTR Presenter: and you're always considering with the exposure pathways. 270 00:33:37,559 --> 00:33:54,529 FRTR Presenter: which exposure pathways are appropriate for media. So like with soil. If it's the top soil you can have the dermal contact. If a child is playing with it, you can have the inhalation of the aerosols from the soil, as they're sort of, you know, spread in the air. 271 00:33:56,670 --> 00:33:57,830 FRTR Presenter: Da-da-da. 272 00:33:59,550 --> 00:34:01,940 FRTR Presenter: so discuss that. 273 00:34:03,210 --> 00:34:12,220 FRTR Presenter: Oh, I knew I had this in here with Sidwell with the Hazard index. I was noting that. My. 274 00:34:13,400 --> 00:34:17,130 FRTR Presenter: well, okay, I'm sorry. You'll note that they 275 00:34:17,880 --> 00:34:30,595 FRTR Presenter: the the receptor, the the dwi body weight that varies. I had in that table, and I apologize. These are kind of out of whack now. 276 00:34:31,390 --> 00:34:38,119 FRTR Presenter: the reason that it varies is, for example for Pfhx. They're looking at a general population adult 277 00:34:38,480 --> 00:34:53,350 FRTR Presenter: for Pf. And A and Hfpo dimer. They're looking at a lactating woman for Pfbs. They're looking at a woman of childbearing age, and that's why. So, in other words, the drinking water and the body mass of that receptor can change at those different stages. 278 00:34:54,790 --> 00:34:58,609 FRTR Presenter: Whereas again, with superfund, when you're talking residential 279 00:34:58,920 --> 00:35:01,929 FRTR Presenter: generally, we're we're looking at the child. 280 00:35:02,770 --> 00:35:09,640 FRTR Presenter: we're not looking at. We we do look at adults. But the sensitive population for residential is generally going to be a child 281 00:35:14,230 --> 00:35:24,859 FRTR Presenter: for the circle of hazard index. I think I already said this, but the exposure is only related to spill or release. So that relative source contribution is only is one. 282 00:35:26,650 --> 00:35:28,519 FRTR Presenter: typically use a child. 283 00:35:28,810 --> 00:35:39,110 FRTR Presenter: And then we do. As I was saying, we update with the new toxicity information. So we will add contaminants, and we update the toxicity of existing contaminants. 284 00:35:44,165 --> 00:35:48,919 FRTR Presenter: yeah. So this is, I've already gone through about the circle. HI. 285 00:35:49,890 --> 00:35:51,930 FRTR Presenter: Just showing that it's 286 00:35:52,050 --> 00:35:54,759 FRTR Presenter: the the Hqs. For all the different pfas. 287 00:35:59,549 --> 00:36:15,850 FRTR Presenter: Sid, I think I went through these again. But this is the table where I was noting the I was discussing that Dwi bw, you can see how it changes. Again. That's because the office of water is looking at different stages. 288 00:36:16,640 --> 00:36:19,650 FRTR Presenter: in other words, a pregnant woman, a lactating woman. 289 00:36:19,870 --> 00:36:21,280 FRTR Presenter: an adult woman. 290 00:36:26,145 --> 00:36:26,610 FRTR Presenter: Okay. 291 00:36:26,940 --> 00:36:36,520 FRTR Presenter: I apologize. That was slightly chaotic. But I I had wanted to get a little bit of extra information in there, because some good questions had been raised when I sent this for review. So 292 00:36:36,890 --> 00:36:46,169 FRTR Presenter: okay, now answer more questions. If you have any. Alright, let's turn to the room. Anyone in the room have a question, because I certainly have a queue online. 293 00:36:49,410 --> 00:36:52,569 FRTR Presenter: All right. Well, then, I'm going to turn back to our virtual audience. 294 00:36:52,800 --> 00:37:11,229 FRTR Presenter: Linda, can you comment to the various Pfas compounds that have Rtds to calculate Hqs. Do they have similar effects as far as the target organs or toxic effects, so that, adding the Hqs. To calculate an Hi would make sense 295 00:37:12,070 --> 00:37:14,140 FRTR Presenter: excellent question, so 296 00:37:14,540 --> 00:37:25,979 FRTR Presenter: I don't memorize off the top of my head. The endpoints for all the different pfas, I will say almost all of them are generally associated with liver effects. 297 00:37:26,447 --> 00:37:39,939 FRTR Presenter: But so, for example, when it comes to the screening levels, because the screening levels are kind of quick, they're just sort of you keep investigating the site. So we're really not looking at endpoints. We're just kind of thinking. 298 00:37:40,270 --> 00:37:41,679 FRTR Presenter: total cancer risk. 299 00:37:41,690 --> 00:37:59,250 FRTR Presenter: total non-cancer risk. But when you go into your full risk assessment at a superfund site, you do need to consider that. So if you have one contaminant, not necessarily pfas. But if you have a contaminant, and its only endpoint is on the kidneys. 300 00:37:59,640 --> 00:38:06,589 FRTR Presenter: Then the risk for that, and then you have another contaminant whose only endpoint is 301 00:38:06,720 --> 00:38:08,840 FRTR Presenter: the lungs. Let's say 302 00:38:09,180 --> 00:38:10,050 FRTR Presenter: you're 303 00:38:10,200 --> 00:38:12,840 FRTR Presenter: generally not going to combine those 304 00:38:14,060 --> 00:38:14,970 FRTR Presenter: but 305 00:38:15,230 --> 00:38:31,670 FRTR Presenter: a little word or caution, which for if you read, for example, the toxicity assessment of basically any contaminant out there you'll have what we call the critical effect. So this is the effect that at the lowest level of exposure there can be an effect. 306 00:38:32,100 --> 00:38:38,479 FRTR Presenter: And so, in other words, if you protect a person from that critical effect, you'll protect them from the other effects. 307 00:38:39,800 --> 00:38:40,950 FRTR Presenter: So 308 00:38:41,160 --> 00:39:07,229 FRTR Presenter: if you most contaminants have more than one effect more than one endpoint. So just because the critical effect is, the kidney doesn't mean you don't consider it with something whose critical effect is the is the the lung, because it might have effects over various different organs. So you have to do. Consider whether or not it's appropriate. 309 00:39:08,280 --> 00:39:11,408 FRTR Presenter: That's why risk assessments are fun. 310 00:39:12,180 --> 00:39:24,829 FRTR Presenter: all right. Another question from online. Can you talk about the reasoning for different receptors used with the Safe Drinking Water Act? Dwibw, is it because of the assessment endpoints. 311 00:39:25,740 --> 00:39:31,519 FRTR Presenter: So I was not a part of this. And if if you want to read the you know. 312 00:39:31,730 --> 00:39:45,439 FRTR Presenter: please read the the real good work. I believe it's, you know, thousands of pages with regard. But yeah, it's normally it has to. When you're considering the the receptor it has to do 313 00:39:45,921 --> 00:39:52,099 FRTR Presenter: with the effects. So if you have a lot of pfas have developmental effects. 314 00:39:52,330 --> 00:39:54,670 FRTR Presenter: so if it's 315 00:39:54,960 --> 00:39:57,699 FRTR Presenter: in other words, if the effect is on the fetus. 316 00:39:57,990 --> 00:40:00,670 FRTR Presenter: then you're considering the pregnant woman. 317 00:40:01,751 --> 00:40:04,118 FRTR Presenter: If the effect is 318 00:40:05,170 --> 00:40:14,120 FRTR Presenter: like on a developing child, then maybe you're considering the lactating woman. And so the explanations are provided, and I apologize. I don't want to. 319 00:40:14,320 --> 00:40:18,390 FRTR Presenter: I don't have their documents memorized, so I don't want to be 320 00:40:18,450 --> 00:40:21,279 FRTR Presenter: saying more, but it it does have to do with 321 00:40:21,350 --> 00:40:23,140 FRTR Presenter: the critical effect. 322 00:40:23,460 --> 00:40:28,320 FRTR Presenter: When can that occur? And then that's why they consider who the receptor is. 323 00:40:29,430 --> 00:40:39,060 FRTR Presenter: Okay. Another question has EPA developed any written guidance on performing risk assessments for pfas that includes legacy. Contaminants 324 00:40:42,220 --> 00:40:47,720 FRTR Presenter: risk assessment, guidance for supervisors. We don't have specific guidance for pfas. 325 00:40:47,990 --> 00:40:48,745 FRTR Presenter: but 326 00:40:50,370 --> 00:40:51,870 FRTR Presenter: rags there's 327 00:40:52,800 --> 00:40:58,960 FRTR Presenter: 5 or 6 different. There's there's rags, part A, BC, 328 00:40:59,110 --> 00:41:00,130 FRTR Presenter: E. 329 00:41:00,240 --> 00:41:07,399 FRTR Presenter: There's several and they're really wonderful documents, because they're 330 00:41:07,620 --> 00:41:08,829 FRTR Presenter: in other words. 331 00:41:09,850 --> 00:41:10,790 FRTR Presenter: they're 332 00:41:12,160 --> 00:41:15,319 FRTR Presenter: They help show how to do these and you 333 00:41:15,440 --> 00:41:20,940 FRTR Presenter: with pfas? We don't need I? I have to keep telling people stop reinventing the wheel. 334 00:41:21,090 --> 00:41:27,380 FRTR Presenter: We we already know how to do risk assessment. We understand this. It's just a new contaminant we got to deal with. 335 00:41:29,610 --> 00:41:40,169 FRTR Presenter: Alright, thank you. And we've had a few people just chime in thanking you for circling back. It was not confusing for them to follow. They appreciated it and go ahead. I see a question in the room. 336 00:41:40,860 --> 00:42:04,970 FRTR Presenter: So I wanted to follow up on that specific question, and I completely agree with you. Don't reinvent the wheel. I think the question is is that it's for a lot of sites that now we are finding out, have co-mingled contaminants. Yes, and a remedy has already been made for those historical contaminants. How you redo the cumulative risk assessment 337 00:42:05,010 --> 00:42:21,679 FRTR Presenter: as part of that? Because now you're gonna have a lot of old data that was used. How do you? How would EPA recommend doing those kind of cumulative assessments without having to go back and resample for everything. 338 00:42:22,960 --> 00:42:26,756 FRTR Presenter: Okay? So we definitely don't have guidance for that. 339 00:42:27,710 --> 00:42:29,790 FRTR Presenter: But conversely. 340 00:42:31,800 --> 00:42:38,690 FRTR Presenter: And so I'm not trying to evade the question. But we always like, for example, when sites go into 5 year reviews 341 00:42:38,780 --> 00:42:43,339 FRTR Presenter: one of the questions with the 5 Year Review. Is, is there new science that needs to be addressed? 342 00:42:43,520 --> 00:42:44,610 FRTR Presenter: So 343 00:42:46,410 --> 00:42:47,240 FRTR Presenter: and 344 00:42:47,270 --> 00:43:06,520 FRTR Presenter: I will say, like, if you have a site, let's say you've been doing pump and treat for 30 years right? And now you discover there's pfas there. Well, maybe you know some of the original contaminants are either not there anymore, or they're at much lower concentration. So I think you're gonna have, you have to reopen the risk assessment. 345 00:43:06,650 --> 00:43:10,530 FRTR Presenter: But you're not necessarily going to be using data from 30 years ago. 346 00:43:10,560 --> 00:43:21,670 FRTR Presenter: right? Because that may not represent what's going on there. But conversely, like, aside from risk, you do need to consider the pfas from the standpoint of 347 00:43:22,640 --> 00:43:27,690 FRTR Presenter: like. If you have a site where you've been using Isco. 348 00:43:27,870 --> 00:43:31,209 FRTR Presenter: that might be like making the Pfas situation worse. 349 00:43:31,290 --> 00:43:40,560 FRTR Presenter: So you need to consider, you know. In other words, okay, how do you deal with the risk, you know? Is there versus the the risk you hadn't considered yet. 350 00:43:42,970 --> 00:43:46,889 FRTR Presenter: I know that's not an answer. But 351 00:43:47,710 --> 00:43:54,689 FRTR Presenter: I I don't see a saying use data from 30 years ago. In other words, what kind of risk is there now? 352 00:43:55,580 --> 00:43:56,660 FRTR Presenter: Does that help? 353 00:43:57,230 --> 00:44:00,909 FRTR Presenter: I see a comment here at the table. Go ahead. 354 00:44:01,700 --> 00:44:06,200 FRTR Presenter: It's a question sure. So similarly, with 355 00:44:06,690 --> 00:44:11,139 FRTR Presenter: not reinventing the wheel, but pfas being kind of a exotic 356 00:44:11,380 --> 00:44:12,700 FRTR Presenter: in some ways. 357 00:44:12,720 --> 00:44:27,009 FRTR Presenter: would EPA ever develop risk exposure, guidelines for concrete or surface water foam which we often hear about in media, but don't actually have risk assessment 358 00:44:27,800 --> 00:44:28,920 FRTR Presenter: methods 359 00:44:29,310 --> 00:44:30,949 FRTR Presenter: to do anything with. 360 00:44:38,980 --> 00:44:51,160 FRTR Presenter: so specifically with foam. I know that, like so, office of research develop office of research and development was working on like an analytical method or like how to sample foam. 361 00:44:51,530 --> 00:44:53,989 FRTR Presenter: And I remember looking at that and thinking. 362 00:44:54,210 --> 00:44:59,239 FRTR Presenter: okay, that's that's good. We're getting data. But like 363 00:44:59,840 --> 00:45:01,580 FRTR Presenter: foam is 364 00:45:02,610 --> 00:45:28,680 FRTR Presenter: like, okay, consider, we, we have I think we probably made up the word recreator. I I don't know that that's a real word, but it's a word we use. So that's to describe. Like, in other words, you have surface water, and we use the term recreator to like this is someone who's coming to swim in a creek once a week, or something like that. And that's our recreator scenario. In other words, obviously, it's extremely site, specifically. 365 00:45:29,290 --> 00:45:31,869 FRTR Presenter: But we consider, in other words. 366 00:45:32,020 --> 00:45:40,420 FRTR Presenter: the with the surface water you're considering inadvertent ingestion of the water while you're swimming, especially a child. 367 00:45:40,780 --> 00:45:48,630 FRTR Presenter: You and you do very much consider the dermal contact. So you have to look at what is the surface area of the body when you're swimming. 368 00:45:49,440 --> 00:45:51,389 FRTR Presenter: So when it comes to foam? 369 00:45:52,027 --> 00:45:55,890 FRTR Presenter: I know they've been looking at. Okay, you have this foam layer on the legs. 370 00:45:56,040 --> 00:45:57,070 FRTR Presenter: Well. 371 00:45:57,110 --> 00:45:58,150 FRTR Presenter: okay. 372 00:45:58,190 --> 00:46:01,100 FRTR Presenter: unless you have the scenario of 373 00:46:02,490 --> 00:46:03,460 FRTR Presenter: like. 374 00:46:04,135 --> 00:46:06,460 FRTR Presenter: you know, somebody sets off 375 00:46:06,530 --> 00:46:29,490 FRTR Presenter: the phone deployment system in a hangar and somebody is going around swimming through 5 feet of foam in this hangar for hours on end, which I kinda hope not. But, in other words, if if that's the case now, you're talking like body wise exposure to the foam right? Whereas if you have surface water, you're gonna have like a thin layer of foam. 376 00:46:30,890 --> 00:46:35,550 FRTR Presenter: I don't know how you work with that. And and the reason is because, in other words. 377 00:46:35,620 --> 00:46:39,119 FRTR Presenter: you are exposed to the foam, there's not a doubt about it. 378 00:46:39,410 --> 00:46:40,990 FRTR Presenter: But the foam is. 379 00:46:41,320 --> 00:46:47,139 FRTR Presenter: you know probably gonna be less than an inch in depth. So what is your 380 00:46:47,670 --> 00:46:49,260 FRTR Presenter: exposure? 381 00:46:49,590 --> 00:46:59,139 FRTR Presenter: And I don't know how to handle that. And and, in other words, because you want to consider it. But you're not swimming in foam. You're swimming in water with contact with foam. 382 00:47:01,500 --> 00:47:02,700 FRTR Presenter: So 383 00:47:03,580 --> 00:47:13,709 FRTR Presenter: that's why we say in superfund. Every side is a snowflake, and you have to figure out how you know what is your reasonable maximum exposure. 384 00:47:14,150 --> 00:47:17,759 FRTR Presenter: But what is the reasonable maximum exposure 385 00:47:17,840 --> 00:47:22,610 FRTR Presenter: which is a non answer, but that's how it needs to be considered. 386 00:47:22,950 --> 00:47:23,720 FRTR Presenter: No. 387 00:47:26,930 --> 00:47:28,250 FRTR Presenter: all right, Kent. 388 00:47:28,360 --> 00:47:58,079 FRTR Presenter: I see you checking your clock. I will just say that there's a lot of comments coming in online supporting your concepts, Linda, that we should be treating pfas like any other site related contaminant. We should be going out there and collecting new data. If it's a new thing that we need to work with, then we go get new data for what's going on right now. So I wanted to chime in and share some of what I'm seeing online. Kent, I'm looking at 1232 by my clock. 389 00:47:59,000 --> 00:48:00,880 FRTR Presenter: What time would that make it.