WEBVTT 00:00:03.000 --> 00:00:12.000 Okay, I think I'm going to get us started. 00:00:12.000 --> 00:00:20.000 So some quick housekeeping rules before we jump in. Today's training is being recorded and it will be offered on demand through Kluen. 00:00:20.000 --> 00:00:23.000 If you're not able to join us during the live session. 00:00:23.000 --> 00:00:27.000 The Kluent training page also has the slides available for download. 00:00:27.000 --> 00:00:38.000 While in Zoom, you will have access to the Q&A window, so please use that for questions to make comments or to report any technical problems during the training. 00:00:38.000 --> 00:00:47.000 Questions and comments that are provided out loud. Please hold until the Q&A breaks. We will try to get through as many questions as we can verbally. 00:00:47.000 --> 00:00:53.000 But if we have too many questions, we're going to ask our trainers to respond directly through the Q&A window. 00:00:53.000 --> 00:01:00.000 If you are interested in receiving a certificate of completion, they are available at the end of the training. 00:01:00.000 --> 00:01:09.000 By completing the feedback form. And the feedback forms are located on the Kluwen training page for the specific course. 00:01:09.000 --> 00:01:16.000 And you can also use that to access the slides. 00:01:16.000 --> 00:01:26.000 Second. 00:01:26.000 --> 00:01:32.000 This journey is an overview of tire-derived chemicals, 6-PPD and 6-PPDQ. 00:01:32.000 --> 00:01:41.000 Quinoa. Chump. 00:01:41.000 --> 00:01:54.000 Itrc is a program of EGOS, Environmental Council of States. We are a state-led organization composed of members from state agencies, federal government, the private sector, academia, and community stakeholders. 00:01:54.000 --> 00:02:00.000 Our members participate in technical teams which produce tools, resources, and training courses. 00:02:00.000 --> 00:02:09.000 Like this one that we're in today. If you'd like to become a member of ITRC, check out our website or feel free to contact us directly. 00:02:09.000 --> 00:02:15.000 On the website, you can learn more about our organization or you can register for Teams. 00:02:15.000 --> 00:02:26.000 The full disclaimer is also available on our website. If you plan to use any ITRC materials, we ask that you review the disclaimer in detail And be sure to credit ITRC. 00:02:26.000 --> 00:02:42.000 Itrc is partially funded by the US government. And ITRC nor the US government warranty the material or endorse any specific products. 00:02:42.000 --> 00:02:55.000 I'm going to pass off. The side controls now to Tanya. 00:02:55.000 --> 00:03:08.000 Thank you, Sabrina. Appreciate it. 00:03:08.000 --> 00:03:17.000 For decades, coho salmon in the Pacific Northwest have experienced massive mortality events as they move through urban centers to their natal streams. 00:03:17.000 --> 00:03:23.000 These mortality events are accompanied by distinct symptoms, including gasping at the water's surface. 00:03:23.000 --> 00:03:29.000 Bin splaying and loss of equilibrium. These die-offs were found to coincide with storms. 00:03:29.000 --> 00:03:38.000 An urban stormwater runoff. But despite the dire consequences for salmon populations, the chemical or compound responsible remained elusive. 00:03:38.000 --> 00:03:46.000 While research focused on mitigation, source control could not be addressed while the mystery compound remained undiscovered. 00:03:46.000 --> 00:03:50.000 Then in 2020, In a research lab in Washington. 00:03:50.000 --> 00:04:04.000 They made a breakthrough. They identified the compound responsible, 6-PPD quinone. 00:04:04.000 --> 00:04:11.000 6-ppd and 6-PPD quinone are contaminants of emerging concern and the science is rapidly evolving. 00:04:11.000 --> 00:04:23.000 So there are many data gaps and unknowns. The current knowledge and what we don't know yet will be discussed within each presentation subtopic. 00:04:23.000 --> 00:04:33.000 A 2011 paper documented a multi-year effort to observe creeks in the Puget Sound watershed with the goal of understanding pre-spawn mortality. 00:04:33.000 --> 00:04:39.000 Up to 100% of coho salmon died before they could spawn in the urban creeks. 00:04:39.000 --> 00:04:46.000 In female carcasses. There was greater than 90% egg retention, indicating they died before they spawned. 00:04:46.000 --> 00:04:55.000 These mortality events were correlated with urban road runoff and were termed urban runoff mortality syndrome, or ERMS. 00:04:55.000 --> 00:05:20.000 But the specific chemicals and runoff responsible remained unknown. Until in 2018, a team of researchers at the UW Tacoma Center for Urban Waters and Washington State University's Washington Stormwater Center started using high resolution mass spectrometry to try to identify the contaminants contained within the tire wear particle leachate. 00:05:20.000 --> 00:05:29.000 Over 2,000 chemicals were identified. Through a series of numerous chemical fractionation processes and approximately three years of work. 00:05:29.000 --> 00:05:41.000 The researchers discovered six PPD quinone in 2020. This discovery was groundbreaking and led to an all hands on deck approach to prevent 6-PBD quinone from reaching coho salmon. 00:05:41.000 --> 00:05:46.000 Later work showed that certain trout and char species also have high sensitivity. 00:05:46.000 --> 00:05:54.000 To six PPD quinone. So what is 6-PPD quinone and where does it come from? 00:05:54.000 --> 00:06:02.000 6-pbd is used as an anti-ozonant and antioxidant in tires to prevent cracking and increase longevity in tires. 00:06:02.000 --> 00:06:08.000 Six PPD is directly responsible for tires meeting some of the tire performance regulations. 00:06:08.000 --> 00:06:18.000 Six PPD is assumed to be present in all tires due to the superior functionality of this chemical in comparison to other anti-ozanic chemicals. 00:06:18.000 --> 00:06:26.000 Six PPD is also found in post-consumer sources made out of recycled tires like crumb rubber for turf fields and play fields. 00:06:26.000 --> 00:06:35.000 Rubber mulch for gardens and rubber floor mats. 6-pbd quinone is a transformation product of 6-PPD. 00:06:35.000 --> 00:06:40.000 And is formed when six PPD reacts with ozone and other oxidizing compounds. 00:06:40.000 --> 00:06:48.000 6 PPD and 6 PPD quinone have different chemical properties that will be explained in more detail later in this presentation. 00:06:48.000 --> 00:06:57.000 The main source of 6-PBD and 6-PBD quinone to the environment is believed to be titerware particles. 00:06:57.000 --> 00:07:07.000 Use of 6-PPD in commercial tires began in the 1960s and mortality of coho salmon was first documented in the 1980s and continues today. 00:07:07.000 --> 00:07:17.000 Research focused on the environmentally and culturally important coho salmon But in 2018, researchers started looking at other salmonid species. 00:07:17.000 --> 00:07:27.000 But the cause was still unknown. It wasn't until 2020 that 6-PB quinone was discovered and determined to be the cause of mortality in the coho salmon. 00:07:27.000 --> 00:07:39.000 More recently, in 2023, The EPA granted a tribal petition to have 6PD banned under Section 21 of the toxic Substances Control Act. 00:07:39.000 --> 00:07:44.000 This map shows the habitat of coho salmon across the country. 00:07:44.000 --> 00:07:53.000 Both native, shown in blue, and non-native shown in orange. Before toxicity data on other fish species were available. 00:07:53.000 --> 00:08:03.000 The 6-PBD quinone problem wasn't viewed as a national issue. Given the limited distribution of the known sensitive species. 00:08:03.000 --> 00:08:10.000 This is not just an issue for the Pacific Northwest. As sensitive species are now found throughout the US and globally. 00:08:10.000 --> 00:08:16.000 Since its discovery, 6-PPD quinone has been found to be acutely toxic to brook trout. 00:08:16.000 --> 00:08:26.000 Rainbow trout and steelhead, lake trout, and coastal cutthroat trout, which are important ecological and recreational species throughout the United States. 00:08:26.000 --> 00:08:33.000 6-ppd quinone is now recognized as a global contaminant and in June of 2024. 00:08:33.000 --> 00:08:41.000 The United States Environmental Protection Agency issued non-regulatory and non-binding screening levels for 6-PPD quinone. 00:08:41.000 --> 00:08:54.000 Governments at various levels here in the United States and globally are increasingly recognizing the impacts of 6-PPD quinone and moving towards regulation. 00:08:54.000 --> 00:08:59.000 Some tribal nations have treaty rights guaranteeing a right to fish and manage salmon. 00:08:59.000 --> 00:09:04.000 The toxicity of 6-PPD quinone to coho salmon and aquatic life threatened that right. 00:09:04.000 --> 00:09:16.000 And raise concerns about nation to nation rights and responsibilities. Tribal nations, both with and without treaty rights, have expressed concern for any impacts to salmon fisheries. 00:09:16.000 --> 00:09:22.000 In part because salmon are culturally significant to many tribal nations in the Pacific Northwest. 00:09:22.000 --> 00:09:28.000 Salmon not only are important for the diet of some tribal nations, but are a part of cultural practice. 00:09:28.000 --> 00:09:36.000 Such as shown here by a member of the Yakima Nation Using traditional dip netting to catch, in this case, Chinook salmon. 00:09:36.000 --> 00:09:40.000 Some tribal nations from this region even identify as salmon people. 00:09:40.000 --> 00:09:50.000 Elevating the significance of salmon well beyond an important food source. Salmon may also be an important part of the economy of some tribal nations. 00:09:50.000 --> 00:09:56.000 Because spawning salmon are a key food source in the ecosystem as well as to the members of the tribes. 00:09:56.000 --> 00:10:04.000 Some have expressed concern about secondary exposures from eating salmon that may contain 6-PPD quinone. 00:10:04.000 --> 00:10:10.000 Salmon are also threatened by concurrent threats, including climate change, habitat loss, and migration barriers. 00:10:10.000 --> 00:10:20.000 Tribal nations are commonly leading advocates for salmon protection. And I've always been involved in conservation efforts and research into urban runoff mortality syndrome. 00:10:20.000 --> 00:10:27.000 And six PPD quinone. They continue to advance discussions, research, and policy. 00:10:27.000 --> 00:10:37.000 This conceptual exposure model shows tire wear particles containing six PPD quinone can be transported through the air or in stormwater runoff. 00:10:37.000 --> 00:10:42.000 The particles can be inhaled and also be deposited on surfaces, soils, and plants. 00:10:42.000 --> 00:10:47.000 6-pbd quinone in surface waters can be ingested and absorbed by fishes. 00:10:47.000 --> 00:11:00.000 Exposed organisms can be ingested by humans and other species. Research is ongoing to further define 6-PBD quinones environmental behaviors, exposures, and the potential development of adverse health outcomes. 00:11:00.000 --> 00:11:14.000 Research is also ongoing on how mitigation measures like green stormwater infrastructure can potentially reduce 6-pbd quinone transport to aquatic systems. 00:11:14.000 --> 00:11:22.000 The guidance document and training cover what we know to date. Six PBD and 6PBD quinone are contaminants of emerging concern. 00:11:22.000 --> 00:11:31.000 Or CECs. And the research is rapidly evolving. The guidance document provides information that was current as of spring of 2024. 00:11:31.000 --> 00:11:40.000 Many questions are being answered while some data gaps remain. So far, only a handful of aquatic species have been tested for toxicity to 6-PPD quinone. 00:11:40.000 --> 00:11:50.000 The mechanism by which its toxicity is not fully understood. The human health effects associated with exposure to these contaminants is relatively unstudied. 00:11:50.000 --> 00:11:57.000 That research is still in its infancy. And many knowledge gaps remain related to the toxological concerns for humans. 00:11:57.000 --> 00:12:05.000 Widespread sampling has yet to begin. Therefore, our understanding of tire and road wear particles, 6 PPD and 6 PPD quinone. 00:12:05.000 --> 00:12:20.000 And their movement through the environment is limited. Until we have a better understanding of the physiochemical properties, fate and transport, occurrence, and human exposure, we will not know the totality of social and cultural impacts. 00:12:20.000 --> 00:12:30.000 Best management practices and source control efforts represent potential solutions. But more information is needed to implement these. 00:12:30.000 --> 00:12:40.000 And now I would like to introduce Ezra Miller, who will do a deeper dive into effects characterization and toxicology. Thanks, Ezra. 00:12:40.000 --> 00:12:50.000 Thanks, Tanya. All right. So in this section, we hope you will learn which species are known to be sensitive to 6-PPD quinone. 00:12:50.000 --> 00:12:55.000 And what we do and do not know about six PPD quinones toxicity to aquatic life. 00:12:55.000 --> 00:13:04.000 And that ecological risk is a combination of the hazard or toxicity of the chemical and the exposure or concentrations in the environment. 00:13:04.000 --> 00:13:13.000 Finally, we will also talk about what we do and do not know about 6-BPD quinone and its risk to human health. 00:13:13.000 --> 00:13:24.000 So although 6PB quinone was only discovered four years ago, there has been a considerable amount of toxicity testing data developed for this compound since then. 00:13:24.000 --> 00:13:36.000 The main focus has been on acute lethality to fish. With limited chronic sublethal testing on fish and limited acute and chronic testing in other aquatic organisms. 00:13:36.000 --> 00:13:44.000 There's almost no data yet on terrestrial species, including humans, and we'll talk about that in a few slides. 00:13:44.000 --> 00:13:52.000 From the data gathered thus far, we know that there is variation both between different species and within a species. 00:13:52.000 --> 00:14:10.000 With clear differences in toxicity to different life stages. And importantly, we don't yet know the toxic mode of action of 6-PP equinone or how various environmental factors and co-stressors like temperature may affect toxicity. 00:14:10.000 --> 00:14:21.000 So what does the data we've collected so far show? Of the species tested, somnenates or salmon, trout, and char seem to be the most sensitive. 00:14:21.000 --> 00:14:31.000 Coho salmon are the most sensitive that we've seen thus far. With LC50s in the nanogram per liter or part per trillion range. 00:14:31.000 --> 00:14:37.000 This table is in micrograms per liter, which is a thousand fold higher than nanograms per liter. 00:14:37.000 --> 00:14:43.000 The LC50 is the exposure concentration that is lethal to half the study population. 00:14:43.000 --> 00:14:49.000 And this is one of the lowest LC50s ever identified in aquatic organisms. 00:14:49.000 --> 00:14:59.000 For reference, 80 nanograms per liter or 0.08 micrograms per liter is the equivalent to four drops in an Olympic sized swimming pool. 00:14:59.000 --> 00:15:04.000 This LC50 is well below concentrations frequently measured in urban stormwater. 00:15:04.000 --> 00:15:16.000 Runoff. Six PPD quinone has been measured as high as 2.85 micrograms per liter in surface waters and onset of symptoms often occurs within 90 minutes of exposure. 00:15:16.000 --> 00:15:24.000 Keep in mind that this is only acute toxicity and does not reflect the potential for sublethal effects. 00:15:24.000 --> 00:15:33.000 So several other salmonid species have also been shown to be very sensitive, although not as extremely sensitive as coho. 00:15:33.000 --> 00:15:39.000 The color changes in this chart represent every order of magnitude change in the LC50s. 00:15:39.000 --> 00:15:49.000 And while not as extraordinarily lethal as coho, these LC50s are still considered to be highly toxic. 00:15:49.000 --> 00:15:57.000 Then there are other solenoids that show very low to no acute toxicity from higher concentrations than have been measured in the environment. 00:15:57.000 --> 00:16:05.000 Once again, keep in mind that this is only acute lethality and does not reflect the potential for sublethal effects. 00:16:05.000 --> 00:16:09.000 You may have noticed that we have included the test duration for this data. 00:16:09.000 --> 00:16:20.000 And this is to show that these numbers are not necessarily directly comparable because they mean that the fish were exposed to the various concentrations of 6-BPD quinone for different lengths of time. 00:16:20.000 --> 00:16:24.000 It's also important to think about in terms of environmental exposures. 00:16:24.000 --> 00:16:42.000 Fisher exposed during rain events when 6PD canon washes into surface waters, and those rain events and elevated 6-PPD quinone concentrations may vary in time from a few hours to several days. 00:16:42.000 --> 00:16:48.000 Outside of dominance, no fish have shown acute mortality at environmentally relevant concentrations. 00:16:48.000 --> 00:17:01.000 And there also does not seem to be much toxicity to daphnids or a growing list of invertebrates like the amphipod hyla. 00:17:01.000 --> 00:17:13.000 I mentioned earlier that we also know that sensitivity to 6-PPD quinone varies not just among different species, but also within a single species, depending on the age of the organism. 00:17:13.000 --> 00:17:22.000 For example, eggs seem to be generally less sensitive, possibly because the chorion, which is a protective membrane that envelops the embryo. 00:17:22.000 --> 00:17:40.000 Is potentially mitigating uptake to the embryo itself. Comparing different independent studies, we also see age-dependent toxicity in coho salmon with LC50s ranging from 41 nanograms per liter in newly feeding approximately three weeks post swim up hatchlings. 00:17:40.000 --> 00:17:48.000 To 95 nanograms per liter in fish over one year old. 00:17:48.000 --> 00:17:56.000 And surprisingly, sensitivity to 6-PPD quinone does not seem to be fully correlated with genetic relationships. 00:17:56.000 --> 00:18:01.000 So this is a phylogenetic tree showing how various tested fish are related. 00:18:01.000 --> 00:18:07.000 The pattern of branching reflects how the species evolved from a series of common ancestors. 00:18:07.000 --> 00:18:13.000 Species are more related if they have more recent common ancestors, so like the Chinook and coho salmon. 00:18:13.000 --> 00:18:20.000 And less related if they have a less recent common ancestor, such as the zebrafish and coho. 00:18:20.000 --> 00:18:28.000 And from this diagram, you can see that closely related species do not necessarily share sensitivity or tolerance to 6-PPD quinone. 00:18:28.000 --> 00:18:37.000 This lack of relationship makes it difficult or even impossible to predict toxicity to untested species with any sort of accuracy. 00:18:37.000 --> 00:18:43.000 Which is a real challenge for risk assessment. 00:18:43.000 --> 00:18:51.000 So how does 6-PV quinone kill salmonids so quickly? Well, we still don't know for sure, but there are now a few hypotheses. 00:18:51.000 --> 00:19:02.000 In early experiments on roadway runoff before the identification of 6-PPD quinone, researchers found that the vasculature of the dying coho leaked. 00:19:02.000 --> 00:19:09.000 Plasma leaked from the gills and plasma also leaked into the brain, indicating failure of the blood brain barrier. 00:19:09.000 --> 00:19:18.000 Genes important for blood vessel architecture are also dysregulated in coho exposed to 6-PD quinolone, which further supports this hypothesis. 00:19:18.000 --> 00:19:24.000 A second hypothesis is that mitochondrial dysfunction might be the mode of toxicity. 00:19:24.000 --> 00:19:33.000 In in vitro testing of different rainbow trout cell lines, gill cells died after exposure to 6-PPD quinone, while liver cells did not. 00:19:33.000 --> 00:19:44.000 And this correlated with oxygen consumption rates, which increased in the gill cells, but not the liver cells. And all of that is to say that it's consistent with some cases of mitochondrial dysfunction. 00:19:44.000 --> 00:19:50.000 A third hypothesis is that toxicity is related to metabolism or biotransformation. 00:19:50.000 --> 00:19:58.000 Higher concentrations of native 6-PPD quinone seem to correlate with increased toxicity in several studies. 00:19:58.000 --> 00:20:06.000 Which suggests that survival may depend on an organism's ability to biotransform PPD quinolones to less toxic metabolites. 00:20:06.000 --> 00:20:24.000 So the mode of action could be any of these hypotheses or a combination of them. And the bottom line is that we still need more research to really understand the molecular initiating event and how these effects follow from that. 00:20:24.000 --> 00:20:31.000 So acute mortality is not the only toxic effect that could have population level effects. 00:20:31.000 --> 00:20:38.000 But the sublethal effects of 6PPD quinone have just started to be explored. 00:20:38.000 --> 00:20:42.000 The species listed on this slide are just the species that have been tested thus far. 00:20:42.000 --> 00:20:53.000 A few recent papers have shown that 6-PPD quinone has some developmental toxicity and delayed mortality in several salmonids exposed as embryos and as hatchlings. 00:20:53.000 --> 00:21:00.000 And one paper has shown that 6-PPD quinone exposure results in the remodeling of the gills. 00:21:00.000 --> 00:21:07.000 Reducing the surface area available for oxygen exchange despite needing more energy. 00:21:07.000 --> 00:21:20.000 Which may disrupt the energy balance of the fish. So you can see the difference in gill structure and surface area between control and 6-PPD quinone exposed fingerlings in these gill histology images. 00:21:20.000 --> 00:21:25.000 Several other papers have also shown a variety of sublethal effects in zebrafish. 00:21:25.000 --> 00:21:36.000 Which are very tolerant to acute effects of 6-PP equinoxone. And while some of these effects only occurred at exposure concentrations well above those found in surface waters. 00:21:36.000 --> 00:21:44.000 Several studies suggest that early life exposure to 6-BPD quinone may cause behavioral changes at environmentally relevant concentrations. 00:21:44.000 --> 00:21:55.000 Which indicates that even tolerant species may experience adverse effects with the potential to affect populations. 00:21:55.000 --> 00:22:03.000 So in general, it appears that 6PPD is much less acutely toxic than 6-PPD quinnone. 00:22:03.000 --> 00:22:15.000 Although it's low stability and formation of transformation products makes its toxicity a lot harder to study. 00:22:15.000 --> 00:22:23.000 So all of these toxicity studies have enabled development of water quality thresholds for 6PPD and 6-PPD quinone. 00:22:23.000 --> 00:22:39.000 We will talk more about these in the policies, regulations, and laws section of the webinar. But for now, just note that these are protective thresholds, so they are lower than the coho LC50. 00:22:39.000 --> 00:22:45.000 So, of course, we're also interested in potential human health impacts in addition to impacts to other species. 00:22:45.000 --> 00:22:58.000 So if we look back at the conceptual model that you saw earlier, we know there are a lot of potential routes of human exposure to tire particles that contain and release six PPD and six PPD quinone. 00:22:58.000 --> 00:23:03.000 As well as the chemicals themselves. 00:23:03.000 --> 00:23:14.000 We know 6-PPD and 6-PPD quinone are present in humans. Biomonitoring studies, primarily in China, have detected both chemicals in urine and blood serum. 00:23:14.000 --> 00:23:26.000 A study on human breast milk found 6-PPD in half of samples, but they didn't find 6pput equinone above the limit of quantification. 00:23:26.000 --> 00:23:36.000 A study on a small number of Parkinson's disease patients found six PPD quinone in cerebrospinal fluid, but they did not analyze for 6-PPD. 00:23:36.000 --> 00:23:49.000 From these studies and studies using mouse models, we know that 6-PPD and 6-PPD quinone can move around in humans and potentially also transmit from parent to fetus and cross the blood-brain barrier. 00:23:49.000 --> 00:24:00.000 However, we still have limited information about potential for bioaccumulation. Or what this exposure may mean for human health. 00:24:00.000 --> 00:24:06.000 There's very little information on the toxicity of 6-PPD quinone to humans. 00:24:06.000 --> 00:24:11.000 Because 6PPD has been in use for a while, we know a little bit more about it. 00:24:11.000 --> 00:24:17.000 6-ppd can cause skin allergies, and it's classified by the European Chemicals Agency or ECA. 00:24:17.000 --> 00:24:31.000 As a reproductive toxic reproductive toxicant. There is also some evidence from rat and mouse studies that chronic exposure to 6-PPD can lead to hepatotoxicity or liver toxicity. 00:24:31.000 --> 00:24:41.000 For 6-PPD quinone, we have only a few mouse studies so far, which have also indicated potential for liver toxicity and reproductive toxicity. 00:24:41.000 --> 00:24:51.000 Studies in other model organisms have also shown potential for neurotoxicity, more reproductive toxicity, developmental toxicity, and carcinogenicity. 00:24:51.000 --> 00:25:01.000 But the relevance of those studies to human health and those observed effects remains pretty unclear. 00:25:01.000 --> 00:25:10.000 So to sum up, the toxicity of 6-PPD and 6-PPD quinone is an active field of research with new papers coming out all the time. 00:25:10.000 --> 00:25:18.000 What we know so far is that 6-ppid quinone is acutely toxic to cocoa and some other solenoids at very, very low concentrations. 00:25:18.000 --> 00:25:25.000 Although we still do not fully understand the toxic mode of action or why some species are more sensitive than others. 00:25:25.000 --> 00:25:33.000 We know that sublethal exposures can also cause toxic effects, but we are only beginning to understand what those may be. 00:25:33.000 --> 00:25:41.000 And while we have a decent amount of data on salmonids, we still don't know much about effects on other aquatic and terrestrial organisms. 00:25:41.000 --> 00:25:50.000 In general, six PPD seems to be less toxic than six PPD quinone, but it's difficult to study because of its chemical properties. 00:25:50.000 --> 00:26:02.000 And finally, we know people are exposed to 6-PPD and 6-PPD quinone, but we do not yet understand what that means in terms of human health. 00:26:02.000 --> 00:26:12.000 So now I'm going to hand it over to Rachel to talk about occurrence, fate, and transport, as well as measuring, mapping, and modeling 6-PPD equinil. 00:26:12.000 --> 00:26:18.000 Thank you, Ezra. 00:26:18.000 --> 00:26:28.000 Great. So in this section, we're going to discuss the sources of 6-PPD and 6-PPD quinone how they are released into the environment. 00:26:28.000 --> 00:26:40.000 Where the compounds have been detected. And we will highlight data gaps and unknowns related to feed and transport. 00:26:40.000 --> 00:26:48.000 Understanding the occurrence of 6-PPD and 6-PPD quinone necessitates a discussion of tire and roadblo particles. 00:26:48.000 --> 00:26:56.000 These are small particles that are generated by friction with the road and tires under normal driving conditions. So just when you're driving your vehicle on a roadway. 00:26:56.000 --> 00:27:03.000 Tire and road wear particles are carried beyond the road surface by a stormwater or other pathways such as dispersion. 00:27:03.000 --> 00:27:14.000 And deposition and can enter aquatic or terrestrial systems. The current and persistence of these particles and chemicals is poorly understood. 00:27:14.000 --> 00:27:19.000 With the fade and transport mechanisms that control currents varying among landscapes. 00:27:19.000 --> 00:27:27.000 Geography, climate, and environmental conditions. 00:27:27.000 --> 00:27:33.000 Understanding the physical and chemical properties is important for discussions of fate and transport. 00:27:33.000 --> 00:27:47.000 An in-depth discussion of these properties is available in the ITRC guidance document and includes properties that are measured in the environment And also theoretical. Therefore, knowledge about these properties is continuing to evolve. 00:27:47.000 --> 00:27:52.000 There are key properties that differ between 6PPD and 6-PPD quinone. 00:27:52.000 --> 00:27:59.000 Meaning they will behave differently in the environment. I'm going to highlight some key aspects here. 00:27:59.000 --> 00:28:11.000 6-ppd is more soluble in water But 6-PPD quinone is still sufficiently soluble to be transported by water until it is captured by organic matter. 00:28:11.000 --> 00:28:15.000 6-ppd quinone is more stable in water with a half-life of weeks. 00:28:15.000 --> 00:28:25.000 Versus less than a day for six PPD. More research is needed to understand the half-life under varying environmental conditions. 00:28:25.000 --> 00:28:30.000 One final aspect to note is that 6PD quinone is hydrophobic. 00:28:30.000 --> 00:28:39.000 Preferentially binding to organic matter and can sorb to plastic containers. 00:28:39.000 --> 00:28:49.000 Since the discovery of 6-PPD quinone in 2020, there has been an increasing number of peer-reviewed studies about the occurrence of 6-PPD and 6-PPD quinone. 00:28:49.000 --> 00:28:55.000 Additional information can be found in the guidance document tables 4-1 through 4-10. 00:28:55.000 --> 00:28:59.000 Where each media type has a table and a study summary. 00:28:59.000 --> 00:29:08.000 These studies are from peer-reviewed literature and do not capture the preliminary monitoring efforts by states, tribes, and local agencies. 00:29:08.000 --> 00:29:17.000 Given the regional specific conditions that impact fate and transport, that should be taken into consideration when interpreting the data. 00:29:17.000 --> 00:29:24.000 As illustrated by the figure, there are currently limited studies on groundwater, drinking water, and roadside soil. 00:29:24.000 --> 00:29:39.000 But stormwater, surface waters, and dust have many publications. We will highlight key areas of occurrence data focusing on the transport and exposure pathways. 00:29:39.000 --> 00:29:51.000 We will first highlight surface water and stormwater, which are major mechanisms for transporting tire and road wear particles six PPD and 6-PPD quinone into receiving surface waters. 00:29:51.000 --> 00:29:58.000 Where concentrations of 6-PPD quinone can be observed above lethal levels for co-host salmon. 00:29:58.000 --> 00:30:12.000 We'll note a range in the reported concentrations. And more studies are needed to understand how environmental conditions such as the landscape the watershed and the stormwater characteristics affect the feet and transport. 00:30:12.000 --> 00:30:31.000 There is limited data about which stormwater and water treatment technologies are most effective at preventing transport of these particles and chemicals. In many places in the US, stormwater is not treated before discharging to surface waters. 00:30:31.000 --> 00:30:36.000 Tire-derived contaminants are washed into water bodies during these storm events. 00:30:36.000 --> 00:30:47.000 Which may lead to temporary peak in 6-PPD quinone concentrations. This storm hydrograph shows the black line of rise and fall in the concentration of 6pdquinone. 00:30:47.000 --> 00:30:59.000 Versus the stormwater discharge in blue. One potent dose in a single storm is enough to cause acute effects in sensitive fish species Even if the average concentrations are very low. 00:30:59.000 --> 00:31:06.000 This is a key difference of 6-PPD quinone relative to other stormwater contaminants. 00:31:06.000 --> 00:31:16.000 A current study should take this into account as a single time point grab sample may not represent an ecologically relevant concentration if you missed the peak. 00:31:16.000 --> 00:31:20.000 It is important to note that the peak in concentration can vary by river. 00:31:20.000 --> 00:31:30.000 Stream and watershed. In larger rivers and watersheds, peak concentrations of 6ppvd quinone may not be observed for many hours. 00:31:30.000 --> 00:31:36.000 After discharge. In smaller tributaries with high amounts of impervious surfaces. 00:31:36.000 --> 00:31:41.000 Peak concentrations may occur in the first hour and are easy to miss. 00:31:41.000 --> 00:31:52.000 The greater the percentage of impervious surfaces within the stream catchment, the more difficult it is to capture the pollutant peak. 00:31:52.000 --> 00:31:57.000 Stormwater and surface water transport the tire and road wear particles. 00:31:57.000 --> 00:32:07.000 And it's shown in the figure. 6-ppd and 6-PPDQ unknown have been detected in river estuary, coastal, and deep sea sediments. 00:32:07.000 --> 00:32:19.000 There are also detections in roadside soil with observed biodegradation and the models and measurements of 6PPD and 6PPD quinone suggest ready binding to soil and organic. 00:32:19.000 --> 00:32:27.000 Additional studies are needed to understand the relationship between the suspended concentrations versus what is deposited onto the soils and sediments. 00:32:27.000 --> 00:32:36.000 Research is ongoing to fill data gaps about the deposition, composition, biodegradation, and the transformation processes. 00:32:36.000 --> 00:32:42.000 Standardized methods for measuring tire and road wear particles in water and sediment are challenging. 00:32:42.000 --> 00:32:54.000 And 6-PPD quinone may provide a proxy for tire-derived bikoplastics. That could represent a continued source of 6-PPD and 6-ppd quinone. 00:32:54.000 --> 00:33:00.000 Tire and rotor particles can disperse 6-PPD and 6-PPD quinone into the air. 00:33:00.000 --> 00:33:07.000 These particles exist as a variety of size fractions, and the diagram illustrates how small the tire particles can be. 00:33:07.000 --> 00:33:21.000 The 50 to 90 micron particles in blue and green will deposit near roadways While they're smaller 2.5 to 10 micron particles shown in yellow and white can remain suspended in the air and be inhaled by organisms. 00:33:21.000 --> 00:33:34.000 Tire and rubber particles increase with proximity to roadways. With 6-PVD and 6-PVD quinone being detected in particulate matter along roads In airborne air and outdoor air. 00:33:34.000 --> 00:33:47.000 And an indoor settled dust. More research is needed to better understand the airborne exposure pathways in humans and in terrestrial and aquatic ecosystems. 00:33:47.000 --> 00:33:53.000 A substantial knowledge gap exists regarding the presence of 6PPD and 6PPD quinone. 00:33:53.000 --> 00:33:57.000 With an edible fish tissue and other aquatic biota consumed by humans. 00:33:57.000 --> 00:34:03.000 As well as whether these levels are sufficiently elevated to pose a risk to human health. 00:34:03.000 --> 00:34:16.000 Determining the concentrations in aquatic food sources and assessing the impacts of various cooking techniques is important for evaluating any potential human exposure and establishing informed consumption guidelines. 00:34:16.000 --> 00:34:24.000 It is unknown whether the ingestion of non-aquatic food sources will expose the consumer to 6-PBD or 6-PBD phenomenon. 00:34:24.000 --> 00:34:31.000 Preliminary studies have shown the uptake of 6-PPD But not 6-BPD quinone into leafy greens. 00:34:31.000 --> 00:34:42.000 But more studies are needed to fill this knowledge gap. It is not yet known whether 6PPD or 6-PPD quinone pose a bioaccumulation risk. 00:34:42.000 --> 00:34:51.000 But early indications are the bioaccumulation potential is low. To moderate. Direct toxicity probably poses the greatest ecological risk. 00:34:51.000 --> 00:35:02.000 More research is needed to confirm bioavailability and bioachemumulation for both compounds in different species. 00:35:02.000 --> 00:35:09.000 Potential roots of human exposure from contact with consumer products may include dermal contact. 00:35:09.000 --> 00:35:16.000 The inhalation of particles and the incidental ingestion of Depending upon the product and usage pattern. 00:35:16.000 --> 00:35:23.000 Additional information is available in Section 4.6 of the guidance document, and as can be seen here in this figure. 00:35:23.000 --> 00:35:31.000 Includes many daily use common consumer products. 00:35:31.000 --> 00:35:38.000 Occurrence, fate and transport studies have confirmed that 6PPD and 6-PPD quinone are present in watersheds. 00:35:38.000 --> 00:35:46.000 Urban runoff, sediment, air, dust, and snow. Confirming some of the risks of exposure in this conceptual model. 00:35:46.000 --> 00:35:56.000 We will now discuss measuring, mapping, and modeling. 00:35:56.000 --> 00:36:01.000 Let me go to the next slide. 00:36:01.000 --> 00:36:08.000 All right. So now we'll shift a little bit. And in this section, we will highlight considerations for study design. 00:36:08.000 --> 00:36:14.000 Mapping tools that can assist in sampling locations. Aspects to consider for field sampling. 00:36:14.000 --> 00:36:26.000 Measuring and laboratory analysis and modeling tools that can predict hotspots or concentrations of 6-PPD and 6-PPD quinone. 00:36:26.000 --> 00:36:30.000 Measuring, mapping, and modeling are critical tools to understand the occurrence. 00:36:30.000 --> 00:36:35.000 State and transport of contaminants Every contaminant has special considerations. 00:36:35.000 --> 00:36:42.000 And we will discuss adaptions to protocols and approaches for 6PPD and 6-PPD quinone. 00:36:42.000 --> 00:36:51.000 Briefly, mapping tools help focus sampling and mitigation efforts. Providing a visualization that is used to inform sampling locations. 00:36:51.000 --> 00:36:59.000 These locations can then be sampled according to standard protocols or best known practices and sent to a laboratory for analysis. 00:36:59.000 --> 00:37:03.000 Data is then used to validate models to make predictions about occurrence. 00:37:03.000 --> 00:37:12.000 Studies continue to repeat this process to advance knowledge about the current transport and risk. 00:37:12.000 --> 00:37:20.000 So mapping tools can focus sampling and mitigation efforts by locating 6PPD and 60 feet equinoid hotspots. 00:37:20.000 --> 00:37:31.000 And potentially vulnerable ecological populations. Key mapping layers that can inform sampling locations include Urban areas with high traffic locations. 00:37:31.000 --> 00:37:38.000 Watershed characteristics with precipitation data. And the habitat range of sensitive species. 00:37:38.000 --> 00:37:44.000 Additional information is available about mapping tools and data layers in Section 5 of the guidance document. 00:37:44.000 --> 00:37:57.000 And as examples, here we're going to highlight a state federal and a risk mapping tool that can be used to inform sampling. 00:37:57.000 --> 00:38:02.000 The first tool we are highlighting is the Washington Department of Ecology Story Map. 00:38:02.000 --> 00:38:13.000 This is a state level mapping tool to identify potential hotspots of 6 PPD quinone near salmon burning water bodies, which can help focus sampling efforts. 00:38:13.000 --> 00:38:18.000 A state-level view is available with areas of interest for 6PPD quinone shown in dark blue. 00:38:18.000 --> 00:38:28.000 You can zoom to your streams of specific interest to see additional information and a vulnerability score. 00:38:28.000 --> 00:38:39.000 The US EPA Freshwater Explorer is a federal level tool highlighting streams that are in close proximity to impervious surfaces. 00:38:39.000 --> 00:38:46.000 When zooming in on a specific location, this mapping tool highlights in red and yellow streams that are near road rays. 00:38:46.000 --> 00:38:57.000 These locations could have high concentrations of 6-PPD or 6-PPD quinone during runoff events. 00:38:57.000 --> 00:39:08.000 The Roads to Ruin paper developed a risk mapping tool that visualizes locations in Washington that could be predicted to have high COHO mortality. 00:39:08.000 --> 00:39:18.000 There is currently a new version in the works that will be released soon for this risk mapping tool. 00:39:18.000 --> 00:39:24.000 So once the locations of interest have been identified, which could be done through some of the mapping tools we just showed. 00:39:24.000 --> 00:39:31.000 Sampling can commence. General guidance for field sampling is available in Chapter 5 of the guidance document. 00:39:31.000 --> 00:39:41.000 And recalling back to some of the physical and chemical properties 6PBD will be anticipated to have a lower detection frequency because of a half-life of less than a day. 00:39:41.000 --> 00:39:52.000 6-ppd quinone is hydrophobic and consort to plastic material. Contact time should be limited with plastic material during both sampling and the analysis. 00:39:52.000 --> 00:40:03.000 6-ppd and 6-PPD quinone can both interact with suspended solids. As long as contact time with plastic materials is minimized. 00:40:03.000 --> 00:40:18.000 Sampling can be done with grab, automated, and passive sampling. Selection of the sampling type will depend on the goals of the project and the ability to time sampling with the storm or the runoff event. 00:40:18.000 --> 00:40:27.000 Sampling in streams and during urban runoff provides environmentally relevant concentrations to be compared with lab toxicity studies. 00:40:27.000 --> 00:40:36.000 Calling the hydrograph the increase and then decrease in concentration should be considered when planning sampling events for 6 ppd quinone. 00:40:36.000 --> 00:40:44.000 Because 6-PD quitone is not a persistent organic contaminant. Sampling must be timed after the rainfall. 00:40:44.000 --> 00:40:55.000 To capture the window of time with the elevated concentration. The exact timing of the rise in concentration varies by watershed hydrograph from the Don River is provided as an example. 00:40:55.000 --> 00:41:00.000 Where the 6PD quinone concentration increases eight hours after the start of the rainfall. 00:41:00.000 --> 00:41:09.000 And remains elevated for 32 hours. Sampling should be time to start after the rainfall to capture the rise in 6PD equinil. 00:41:09.000 --> 00:41:15.000 This means that sampling during dry weather or the times when you would really want to be out in the field and it's a nice day. 00:41:15.000 --> 00:41:22.000 We'll probably miss the peaks of 6PP equinome. 00:41:22.000 --> 00:41:33.000 So one technique for sampling watersheds and stormwater is grab samples, which need to be timed appropriately with that elevated PPD quinone concentration. 00:41:33.000 --> 00:41:37.000 This approach captures a snapshot in time of the environmental concentration. 00:41:37.000 --> 00:41:45.000 Recall that glass bottles are recommended for sampling 60 feet quinone and plastic should be avoided. 00:41:45.000 --> 00:41:55.000 Auto sampling is advantageous sampling approach during storm events because it can be programmed to collect discrete or continuous sampling over the course of the entire storm. 00:41:55.000 --> 00:41:59.000 Storms can happen at inopportune times, so it could be evenings, it could be weekends. 00:41:59.000 --> 00:42:05.000 Automated sampling can be programmed to capture the maximum concentration and measure how long it remains elevated. 00:42:05.000 --> 00:42:10.000 Without somebody having to physically be in the field for that entire window of time. 00:42:10.000 --> 00:42:25.000 While the grab sampling provides a snapshot. The auto sampling is the equivalent of filming a short movie. It can capture samples or time weighted samples over the entire storm event. 00:42:25.000 --> 00:42:32.000 A longer-term sampling tool to provide the time-weighted average concentration of contaminants is passive sampling. 00:42:32.000 --> 00:42:36.000 The passive devices are deployed in the field and left for days to weeks. 00:42:36.000 --> 00:42:41.000 Many are relatively affordable and some mimic the bioavailability of contaminants. 00:42:41.000 --> 00:42:50.000 This is particularly useful for 6-PPD quinone that is transported during storm events and persists for only hours to days in surface waters. 00:42:50.000 --> 00:43:03.000 Before settling to the benthic environment or being transported downstream. Preliminary investigations are underway to evaluate several different types of passive samplers for 6-phpdquinolone. 00:43:03.000 --> 00:43:16.000 Currently available active and passive sampler approaches in air have also been investigated for 6PPD And six feet equally known with air sampling. 00:43:16.000 --> 00:43:25.000 So after samples are collected, commercial public and research laboratories are available for the analysis of 6-PPD and 6-PPD quinone. 00:43:25.000 --> 00:43:34.000 In a range of environmental matrices. When selecting a laboratory, be sure it provides the analytical rigor required for project or program goals. 00:43:34.000 --> 00:43:46.000 Laboratory method accreditation, method detection limits, sample holding times, quality control parameters should be reviewed to ensure data will meet the desired quality and reproducibility. 00:43:46.000 --> 00:44:01.000 Analytical method accreditation varies by state, organization, and agency. Stormwater and surface water can contain a range of suspended solids and Because 6-PPD and 6-PPD quinone consort to organic material. 00:44:01.000 --> 00:44:17.000 It is important to consider if the measurement is providing the dissolved aqueous concentration The suspended solid concentration or the total, which is the dissolved plus the suspended concentration. 00:44:17.000 --> 00:44:24.000 So for the measurement of 6 pd There is not a standardized or approved method. 00:44:24.000 --> 00:44:33.000 Due to the instability of 6PP. Laboratories have investigated the use of ozone scavengers to increase stability and laboratory hold times. 00:44:33.000 --> 00:44:52.000 But they resulted in unstable conditions for 6-BPD quinone. Liquid chromatography mass spectrometry, LCMS, or gas chromatography mass spectrometry, GCMS, are the most common analysis techniques and provide an estimate of 6-PVD. 00:44:52.000 --> 00:45:03.000 Lcms and GCMS are advantageous analytical techniques because of their adaptability to biotic and abiotic matrices environmentally relevant low detection, method detection limits. 00:45:03.000 --> 00:45:12.000 And suitability for targeted, someone targeted, and non-targeted screenings. 00:45:12.000 --> 00:45:17.000 For the measurement of 6-PPD quinone, there is an EPA draft method available. 00:45:17.000 --> 00:45:25.000 Use of approved method will depend on the goals of your study, but a standardized method reduces variability that could occur between different techniques. 00:45:25.000 --> 00:45:34.000 The EPA method 1634 recommends collection in amber glass bottles A 14-day hold time pre-extraction. 00:45:34.000 --> 00:45:43.000 The 28-day hold time post-extraction and provides the total concentration, the dissolved plus the total suspended solvent. 00:45:43.000 --> 00:45:49.000 The US Geological Survey research method also demonstrates stability of 6-PP quidone during freezing. 00:45:49.000 --> 00:46:10.000 Which could increase sample hold times for laboratories. Research methods for other media have used a variety of extraction techniques coupled with LCMS and GCMS to provide concentrations in air, soil, sediment, tissues, food, and consumer products. 00:46:10.000 --> 00:46:19.000 Data generated from the mapping, sampling, and measuring can be used with established modeling tools to predict the occurrence of 6PPD and 6-PPD quinone. 00:46:19.000 --> 00:46:28.000 This can help to inform and focus sampling for hotspots in your potentially vulnerable ecosystems and informal locations for mitigation. 00:46:28.000 --> 00:46:37.000 Epa tools for atmospheric fade and transport modeling have been applied to understand the emission and transport of tire and roboparticles. 00:46:37.000 --> 00:46:42.000 Recently, the VOMA tool was applied to 6-BPD quinone to predict hotspots. 00:46:42.000 --> 00:46:49.000 And types of green infrastructure to reduce 6-PPD quinone. 00:46:49.000 --> 00:46:53.000 So occurrence, fate and transport studies Along with the mapping and modeling tools. 00:46:53.000 --> 00:46:59.000 Have identified locations of potential hotspots for 6PPD and 6-PPD phenomenal. 00:46:59.000 --> 00:47:09.000 All this data can inform the mitigations portion of the conceptual exposure model to identify locations for source control and prioritize green infrastructure treatments. 00:47:09.000 --> 00:47:13.000 That can most effectively reduce contaminant loadings to threatened aquatic habitats. 00:47:13.000 --> 00:47:24.000 And now it's my pleasure to pass this to Mark Shorter, who will talk about mitigations, measuring, and solutions, and also policy. 00:47:24.000 --> 00:47:34.000 Thank you, Rachel. Mitigating the effects of 6-PPD and 6-PPD quinone requires consideration for both the near and long-term solutions. 00:47:34.000 --> 00:47:44.000 The best approaches holistically protect both the aquatic organisms and potentially even people should 6-PPDQ be found to have adverse effects on human health. 00:47:44.000 --> 00:47:54.000 So we'll be reviewing different types of mitigation measures that may address 6 PPD and 6 PPD quinone in multiple environmental realms. 00:47:54.000 --> 00:48:05.000 For this section, we hope you'll walk away with knowledge on what mitigation practices are currently being explored, including ongoing efforts and research in alternative chemicals, stormwater and sediments. 00:48:05.000 --> 00:48:16.000 The ultimate goal is to optimize the balance between mitigation effectiveness and feasibility to have the widest reaching results. 00:48:16.000 --> 00:48:30.000 The long-term solution to mitigating 6-PPD quinone is the replacement of its parent chemical 6PPD We must ensure alternatives assessments are thorough to avoid unintended consequences of new chemical substitutes. 00:48:30.000 --> 00:48:41.000 The National Research Council defines and alternatives assessment as the process for identifying and comparing potential chemical and non-chemical alternatives that could replace chemicals of concern, 6PVD. 00:48:41.000 --> 00:48:49.000 And 6BD quinone on the basis of their hazards, comparative exposure, performance, and economic viability. 00:48:49.000 --> 00:48:59.000 So this flowchart from California Department of Toxic Substance Control shows the life cycle at which these and other technical factors must be considered. 00:48:59.000 --> 00:49:06.000 There has been rapid progress in just the past year with the intersection of policy and research, which we'll talk about in the next section. 00:49:06.000 --> 00:49:14.000 And right now, alternatives are being evaluated under rigorous criteria considering 6 PPD is vital for tire safety and performance. 00:49:14.000 --> 00:49:23.000 We also need to remember that the chemical is shed through tire and road wear particles, so we know that there will be widespread exposure to any replacement chemical. 00:49:23.000 --> 00:49:35.000 So in short, toxicity, performance, safety, and feasibility must all be considered before an alternative is selected. 00:49:35.000 --> 00:49:40.000 Understanding and controlling the chemical sources are the first lines of defense in the near term. 00:49:40.000 --> 00:49:48.000 These near-term strategies are founded upon our understanding of how these chemicals move through the environment, like Rachel described earlier. 00:49:48.000 --> 00:49:54.000 Source controls are covered in the guidance document with examples such as alternatives to driving personal vehicles. 00:49:54.000 --> 00:50:06.000 Like public transportation and walkable communities addressing driver behavior with outreach and educational campaigns as driver behavior has a direct impact on the generation rate of tire wear particles. 00:50:06.000 --> 00:50:17.000 Frequent or sudden acceleration and braking as well as sharp high speed turns can increase the rate at which pirate where particles are generated. 00:50:17.000 --> 00:50:28.000 On their emerging technologies with car designs, one being tire wear particle capture devices. And finally, stormwater control measures. 00:50:28.000 --> 00:50:35.000 Or actions and strategic locations that can control the load of tire wear particles into the environment and waters. 00:50:35.000 --> 00:50:48.000 On the next slide, I'll speak in a bit of what goes into SCMs because the planning of SCMs are significant for managing six PPD transport. 00:50:48.000 --> 00:50:59.000 With the effects to coho salmon and other sensitive species, there's been a rapid response from stakeholders in moving many pieces of the mitigation puzzle forward simultaneously. 00:50:59.000 --> 00:51:03.000 The steps to stormwater planning might look like these four panels on the right. 00:51:03.000 --> 00:51:13.000 6-pbd quinone is incredibly unique in that it is both in the water quality assessment phase and it's also being considered in SCMs. 00:51:13.000 --> 00:51:19.000 As in, we must understand the fate and transport in order to engineer any mitigation. 00:51:19.000 --> 00:51:35.000 On assessing the water quality by characterizing the stormwater and identifying hot spots and then using that to plan for mitigation by determining which SCMs are effective, appropriate, and practical to maintain. 00:51:35.000 --> 00:51:43.000 After planning, implementing, and monitoring, the SEMs must work across local, state, federal, and tribal partnerships. 00:51:43.000 --> 00:51:51.000 And finally, the potential for remediation. Which we won't talk about now. 00:51:51.000 --> 00:51:58.000 There are several types of stormwater SCMs that are projected to have a high probability of mitigating 6-PBD quinone. 00:51:58.000 --> 00:52:06.000 Variations of the three SCMs in this slide are predicted to be effective to slow the flow of runoff and reduce and remove pollutants. 00:52:06.000 --> 00:52:11.000 Through stormwater systems because of the affinity for 6 PPD quinone. 00:52:11.000 --> 00:52:26.000 To sort organic matter. On the left. Source control SCMs can prevent stormwater contaminants from entering storm drainage systems, inhibiting their ability to enter the water to enter receiving waters. 00:52:26.000 --> 00:52:32.000 These might include street sweepings and the cleaning of roadside ditches, catch basins and storm pipes. 00:52:32.000 --> 00:52:42.000 Preliminary studies have intuitively demonstrated that increased frequency of storm sweepings reduces tire wear particles in stormwater. 00:52:42.000 --> 00:53:01.000 In the middle panel, flow control SCMs, that slow runoff and reduce the runoff volume through on-site management of water are effective. This method of management contradicts the designs of many older roadways where storm water is flushed off of the road and into waterways very quickly to prevent flooding. 00:53:01.000 --> 00:53:11.000 Examples, flow controls include bioretention swales infiltration basins, detention ponds, or permeable pavements. 00:53:11.000 --> 00:53:34.000 And lastly, runoff treatment storm SCMs that can reduce concentrations of targeted pollutants through the means of physical filtration or chemical sorption are effective. To date, bioretention soil mixes, which contain stormwater compost mix of 60 40 sand and compost are identified as one of the most effective 00:53:34.000 --> 00:53:50.000 Methods of reducing 6-PPD quinone exposure and mortality in fish. Specialized high performance bioretention mixes optimal for nutrient sensitive water bodies are also showing preliminary promise. 00:53:50.000 --> 00:54:08.000 Pictured here is just a simple compost sock in a detention pond that treats the stormwater before it can enter the waterway and In the end, these treatments are most effective when designed together with flow controls. 00:54:08.000 --> 00:54:20.000 Currently, SCM practice researchers are working on optimizing technologies for the most efficient and long-lasting SCMs and maximizing 6PPD, quinone, and tire wear particle removal. 00:54:20.000 --> 00:54:39.000 In 2022, the BMP Effectiveness Report published by The Washington State Department of Ecology examined existing stormwater SCMs to assess each for their potential efficacy at mitigating six PPD quinone. And that's linked at the bottom of the slide. 00:54:39.000 --> 00:54:52.000 And the primary takeaway is that mitigation measures should take advantage of the chemical properties. Again, remembering that both chemicals have a high affinity to partition out of water and onto organic matter. 00:54:52.000 --> 00:55:04.000 Ongoing research is studying what happens to 6-PPD quinone after it has been filtered out. There's a number of questions related to remobilization and the maintenance of these SCMs. 00:55:04.000 --> 00:55:12.000 And there's more discussion in section six of this guidance document. 00:55:12.000 --> 00:55:20.000 Now we'll be talking about some of the policies, regulations, and laws that have an effect on 6PPD. 00:55:20.000 --> 00:55:29.000 By the end of this section, we hope you'll gain an understanding of the following. Which federal policies, laws, and regulations might apply to the management of 6PPD? 00:55:29.000 --> 00:55:35.000 Who the stakeholders for regulatory actions are and what levels of government they can be found at. 00:55:35.000 --> 00:55:47.000 Which states and tribes are currently driving efforts towards regulatory actions And how nationwide awareness is growing and expected to trigger federal actions. 00:55:47.000 --> 00:56:03.000 Section 7 of the guidance document identifies the many federal level regulations, policies, and laws that might affect the potential future regulation of Six PPD, six PPD quinone, and tires. 00:56:03.000 --> 00:56:11.000 Though only a few legal governances are currently considering the chemicals. The notable ones are in these colored boxes. 00:56:11.000 --> 00:56:16.000 Tribal treaty rights supersede laws because they represent nation to nation treaties. 00:56:16.000 --> 00:56:32.000 A toxic Substance Control Act, the Clean Water Act. And in addition, we've seen major regulatory actions from states and tribes. And this is not meant to definitively speak to any given entity's jurisdiction over an issue or decision, just to highlight. 00:56:32.000 --> 00:56:44.000 Where much of this regulatory action is currently based. We'll begin with the TSCA case study and how it's closely tied to tribal treaty rights. 00:56:44.000 --> 00:56:51.000 We want to emphasize on the speed of this movement comparatively and that this timeline is rapidly changing. 00:56:51.000 --> 00:57:00.000 In August of 2023, a petition from Earth Justice on behalf of the Puyallup tribe of Indians, the Port Gamble Sklalom tribe. 00:57:00.000 --> 00:57:08.000 And the Yurok tribe asked the EPA to prohibit the manufacturing, processing, use, and distribution of 6-PBD in tires. 00:57:08.000 --> 00:57:18.000 And the next month in September, the affiliated tribes of Northwest Indians passed a resolution supporting the petition. 00:57:18.000 --> 00:57:27.000 In November of 23, the EPA granted the petition with the first steps to publish advance notice of proposed rulemaking to gather more information. 00:57:27.000 --> 00:57:42.000 And by the end of 2024, to finalize the EPA to finalize the rule requiring manufacturers of 6-PPD to report less than copies of unpublished health and safety studies. 00:57:42.000 --> 00:57:47.000 The next legal government governance is the EPA's response under the Clean Water Act. 00:57:47.000 --> 00:57:54.000 The numbers shown here are hazard-based screening levels and are not enforceable standards. 00:57:54.000 --> 00:58:01.000 These values are the super low concentrations where researchers first see acute toxicity effects. 00:58:01.000 --> 00:58:15.000 Based on the available toxicity data for aquatic life. 6-ppd and 6-PPD quinone concentrations below these values will not pose a significant risk to the majority of species in said ecosystem. 00:58:15.000 --> 00:58:29.000 Note that these values are conservative or lower. Than some of the concentrations we noted in toxicology in the toxicology slides, because if you recall in that toxicity chart. 00:58:29.000 --> 00:58:34.000 Those numbers are based off of the LC50, but regulations are not. 00:58:34.000 --> 00:58:43.000 Based off of those numbers. 00:58:43.000 --> 00:58:50.000 As I mentioned earlier, Washington and California are working to address 6PBD from multiple points of potential action. 00:58:50.000 --> 00:59:03.000 Among those actions include searching for a replacement of 6-PPD, And both states have programs that are working alongside and industry stakeholders to identify alternative PPDs. 00:59:03.000 --> 00:59:15.000 California does so through its safer consumer products regulation, which requires an alternatives analysis to investigate safer alternatives to six PPD and tires. 00:59:15.000 --> 00:59:25.000 So far, 75 tire manufacturers have completed stage one alternative analyses with 17 possible alternatives to 6 PPD. 00:59:25.000 --> 00:59:38.000 In Washington. Washington is working through the Safer Products for Washington program to review hazards and identify alternatives, both of which will inform future rulemaking and restrictions. 00:59:38.000 --> 00:59:52.000 Washington's Department of Ecology is completing an alternative assessment using hazard criteria developed specifically for 6PPD, including data requirements for sensitive species and other trophic levels. 00:59:52.000 --> 00:59:59.000 So effective policy development is closely tied to scientific research, which is still in its early stages. 00:59:59.000 --> 01:00:09.000 Significant knowledge gaps remain, requiring continued investigation to make practical regulations that can be implemented via SCMs or alternatives. 01:00:09.000 --> 01:00:19.000 Some initial regulations have already begun. Including stormwater permits with mitigation and retrofit guidance, as well as EPA petition rulemaking. 01:00:19.000 --> 01:00:31.000 Alternatives remain the highest priority for the mitigation efforts. But are still in the varying stages of research and implementation. 01:00:31.000 --> 01:00:44.000 Our guidance document contains more detailed information on all of these topics. So we'll pause here So you can use this QR code to get to it. 01:00:44.000 --> 01:00:57.000 And I will now pass it back to the moderator. 01:00:57.000 --> 01:01:10.000 All right, great. So we're going to jump over to the Q&A. Sorry, losing my voice a little We're going to… talk about some of the questions that are still open and possibly jump back to some of them that are answered. 01:01:10.000 --> 01:01:14.000 If they're good questions. Oh. 01:01:14.000 --> 01:01:25.000 Okay, are there any other compounds like HMM that have a similar impact or seven PPD, etc. 01:01:25.000 --> 01:01:43.000 So I can start an answer to this, which is that We have not found any other compounds that are as absurdly toxic as 6-bp equinrone in terms of tired chemicals H triple m seems to generally be a lot less toxic. 01:01:43.000 --> 01:01:49.000 The other PPDs are toxic. But not as absurdly toxic. 01:01:49.000 --> 01:02:02.000 So I know in California, several of those other PPDs are being considered in the alternatives analysis that's being done through DTSC's Safer Consumer Products. 01:02:02.000 --> 01:02:09.000 Process. And Kelly may be able to give us more info on that. 01:02:09.000 --> 01:02:36.000 Thanks, Ezra. Yeah. So one of the things that um the US tire manufacturers Association is doing in association with Washington State's Department of Ecology is looking at other PPD quinones and the toxicity of those And so far, it does seem like six PPD quinone is 01:02:36.000 --> 01:02:44.000 As Ezra used the term absurdly toxic, whereas the other TPD quinones are not as toxic. 01:02:44.000 --> 01:02:51.000 But certainly, you know, this is still an area of evolving knowledge. 01:02:51.000 --> 01:02:57.000 So stay tuned. 01:02:57.000 --> 01:03:04.000 Thank you, Kali and Ezra. All right, going to jump on. There is another question. 01:03:04.000 --> 01:03:32.000 Has the presence of six PPD, quinoa. Sorry, Kenwa, in different industrial areas been studied are specific industries of concern. 01:03:32.000 --> 01:03:43.000 Kelly, maybe I think you might have a good answer to this. I would say in general, we're most concerned about roadway runoff at this point in time. 01:03:43.000 --> 01:03:50.000 Yeah, I would just echo that and say that I think It's probably a bit of a data gap. 01:03:50.000 --> 01:04:00.000 You know, probably the other places we'd expect to see 6ppe and 6PPD quinone discharges would be from tire manufacturing facilities. 01:04:00.000 --> 01:04:08.000 And maybe retreading facilities Because they grind down the tire to adhere a new tread to it. 01:04:08.000 --> 01:04:21.000 So there's a lot of particulate production in those facilities. And as far as I know, that's a data gap that has not been assessed yet 01:04:21.000 --> 01:04:28.000 And I'll also chime in and point out too, we also have to think about these facilities that you sometimes need a mobilization event. 01:04:28.000 --> 01:04:35.000 Because we were next to like a tire manufacturing facility and it was during a drought with low flow conditions like all summer. 01:04:35.000 --> 01:04:38.000 And we didn't have any detections, but there was nothing mobilizing. 01:04:38.000 --> 01:04:45.000 This contaminant from the industrial facility. 01:04:45.000 --> 01:04:50.000 Thank you all for the answers. I'm going to jump on. There's another question. 01:04:50.000 --> 01:04:59.000 What has been the tire manufacturer's response or actions to the new information? 01:04:59.000 --> 01:05:05.000 I'll tackle that one. Excuse me. So that's a great question. 01:05:05.000 --> 01:05:25.000 I'm from the California Department of Toxic Substances Control and that paper consumer products program that was discussed And the US Tire Manufacturing Associate Manufacturers Association came to us and actually requested that we regulate six PPD and tires. 01:05:25.000 --> 01:05:40.000 So they have been very proactive about looking for alternatives And they've been engaging with us in our process that requires them to find safer alternatives. 01:05:40.000 --> 01:05:47.000 Certainly, you know. As a fish lover, I would love to see this process go faster. 01:05:47.000 --> 01:06:03.000 But we have to ensure that tires are safe as well. So it is a slow process. 01:06:03.000 --> 01:06:11.000 I noticed the question, what happens in the meantime if the EPA bans this chemical compound for use in tires via regulations? 01:06:11.000 --> 01:06:16.000 Without an alternative, do we have to all buy new tires? 01:06:16.000 --> 01:06:26.000 Trying to talk about the practical impacts. 01:06:26.000 --> 01:06:51.000 I think EPA is aware of the concerns about making sure that alternatives are available and safer as they go through their process, particularly in regard to the tribal petition I don't want to speak to what they would do. That's beyond my purview, but I think there are 01:06:51.000 --> 01:07:00.000 Generally aware of the concerns. 01:07:00.000 --> 01:07:08.000 Is this a problem all the time? Are sensitive fish only there at certain times? 01:07:08.000 --> 01:07:24.000 So, um. Some men are anonymous, which means that they are in both freshwater and saltwater, and they're migrating through these streams that are near roads and that is when They are exposed to the runoff. 01:07:24.000 --> 01:07:33.000 So yeah, absolutely. It has to be when it is raining and 60 feet equinrone is running off the roads. 01:07:33.000 --> 01:07:40.000 And the fish are also present, which isn't always. Unfortunately, in the Pacific Northwest. 01:07:40.000 --> 01:08:10.000 The timing of the rainy season and the coho migration overlap. And so that effects happening. But I think in some places this may be um more of a nuanced issue. So for example, I work for the San Francisco Estuary Institute, which is a nonprofit that does science to inform policy in California. 01:08:10.000 --> 01:08:16.000 We are concerned not just about coho, but also about steelhead and rainbow trout. 01:08:16.000 --> 01:08:37.000 And those fish may not always be present when the runoff events are happening. But it's something that we're still thinking about and trying to figure out when it's most when When it's most important. And a lot of the mapping stuff that Rachel talked about can help us 01:08:37.000 --> 01:08:47.000 Identify those areas where there are fish and also runoff events happening together. 01:08:47.000 --> 01:08:48.000 Thank you, Ezra. All right. It looks like 01:08:48.000 --> 01:09:03.000 And I'll just… I'll chime in a little bit more on that. Just keep in mind, the fish that we're talking about here are often using the level of water in a stream or it's for fish that are saltwater and freshwater 01:09:03.000 --> 01:09:08.000 The relative amount of fresh water coming out to actually smell and find and track their way through their systems. 01:09:08.000 --> 01:09:25.000 So they're adapted to find the waterways that have higher flows and that's why it's tied with rain year season. So salmon stage at a lot of streams and rivers and watersheds waiting for large flood events from rains hitting watersheds. 01:09:25.000 --> 01:09:35.000 To go upstream and to find space to spawn. And the same thing with inland waters. A lot of times the fish will go to the streams when there are high flood events, when there's a lot of water moving through a system. 01:09:35.000 --> 01:09:49.000 So they can access different parts of the watershed that they weren't able to access during low flow drier season. So not only is there the toxicology issues with this from an individual fish in a lab in a tank with a chemical 01:09:49.000 --> 01:09:58.000 But it's really the ecological layer on top of this that these fish that are so affected by the toxic chemical here by 6 feet. 01:09:58.000 --> 01:10:15.000 Are tied to places where there's lots of water flowing through the system. So that's where, as Ezra mentioned, the mapping is going to help us figure out prioritization places and where some of these come to a head most. 01:10:15.000 --> 01:10:31.000 Thank you, Sean. I noticed another question on here that looks like Mark wanted to answer. Has any remediation been done to mitigate 6-BD N6 PBD quinone on road runoff. 01:10:31.000 --> 01:10:45.000 Yeah, I think I can answer this and just some of the there's a couple other questions that are similar that we can knock out. But in general, a lot of the research and focus has been looking at six PPD as more of a non-point source um 01:10:45.000 --> 01:11:05.000 Contaminants, so remediation really has only been kind of considered as like a thought experiment as far as like where you could remediate and where 6 PBD and 6 PPD quinone would actually be accumulating for that to be possible, whether that's at like the 01:11:05.000 --> 01:11:20.000 Like at a manufacturing facility or if it's accumulating in sediments and those are kind of questions that are really just knowledge yaps right now. 01:11:20.000 --> 01:11:25.000 Thank you for that, Mark. We're going to try to get through as many questions as possible. 01:11:25.000 --> 01:11:32.000 All right. There's another one. For SCMs that filter out six PPD, 6 PBD, quinone. 01:11:32.000 --> 01:11:43.000 Out of stormwater, what is done with the filtration media once it's full? 01:11:43.000 --> 01:12:01.000 I think that's also being studied. And figure it out. I know there's a couple, I know there's research efforts through the state of Washington that are looking at that right now at some of the local universities but Yeah, right now there's no regulation to be able to 01:12:01.000 --> 01:12:13.000 Say what you have to do for maintenance. The operations of these filtration mechanisms. 01:12:13.000 --> 01:12:33.000 Great. Thank you. And someone asked if we could talk about any studies at rubber manufacturing and recycling facilities. 01:12:33.000 --> 01:12:39.000 But in terms of like environmental levels near them 01:12:39.000 --> 01:12:49.000 I think we kind of answered that a little bit about industry. It's kind of the same answer there. 01:12:49.000 --> 01:12:55.000 Okay, I'll jump on. 01:12:55.000 --> 01:13:01.000 I'd say on the industrial site ones, there's a lot of data gaps to be looked at there. 01:13:01.000 --> 01:13:20.000 And as more of the human health pathways to exposure gets studied and there's, as we mentioned, during the retreading facilities, a lot of the recycling facilities where There might be a lot of dust kicked up in the air. These are all things that are data gaps or things that are being actively looked at. 01:13:20.000 --> 01:13:39.000 And as of right now, given the origin of this 6PBD as a salmon and other fish focused um problem a lot of the exploration is on where the most sources of 6pvdq to the environment and a lot of that, as we mentioned in a couple of the other comment responses. 01:13:39.000 --> 01:13:50.000 Are usually tied to roadways, but that doesn't mean that there aren't other hotspots and those can pop up in myriad ways. And just like one of the questions about astroturf and sports fields. 01:13:50.000 --> 01:14:03.000 Some of the studies cited in the ITRC report online show that if there are some fields that use different types of rubber that don't have 6 PBD in them. And so there's a lot more detail is needed for any given hotspot. 01:14:03.000 --> 01:14:09.000 Or any given field or any given industry to determine kind of the relative levels of exposure. 01:14:09.000 --> 01:14:18.000 Based on the amount of six PPD, even in a feedstock, a rubber that goes into that facility or is processed at a facility or at a park. 01:14:18.000 --> 01:14:30.000 So it's going to take a lot more investigation into a lot of the nuances of any given site in order to answer some of those questions. 01:14:30.000 --> 01:14:40.000 Thank you, Sean. There's a newer question. Are we primarily concerned with dissolved phase six PPD or partial ingestion? 01:14:40.000 --> 01:14:42.000 Do we know? 01:14:42.000 --> 01:14:49.000 So I would say the dissolved phase six PPD equinrone, we are more concerned about. 01:14:49.000 --> 01:14:55.000 And the problem with the particles is that they are a source of these chemicals. 01:14:55.000 --> 01:15:03.000 And there are studies showing that there are exposure to tighter particles. 01:15:03.000 --> 01:15:12.000 Causes all sorts of toxic effects as well. Not just the 6-PPD quinone related effects, but other toxic effects as well. 01:15:12.000 --> 01:15:21.000 And so It's a complicated problem. We often will think about both the chemicals and the particles. 01:15:21.000 --> 01:15:32.000 As a way to try and get at that. Yeah, right now that's still kind of an open question. 01:15:32.000 --> 01:15:46.000 Thank you, Ezra. Has anyone investigated septic tanks for 6pbd quinone and if they could be an exposure to private domestic wells. 01:15:46.000 --> 01:15:59.000 I personally would be surprised if septic tanks had a lot of six feet equinone because that is a you're not you're not putting tires into your subject tank. 01:15:59.000 --> 01:16:08.000 In terms of groundwater, there have been a few groundwater studies so it Maybe. But once again. 01:16:08.000 --> 01:16:23.000 That doesn't seem like as direct a route for 6-PPD quinone or 6-PPD to get to. 01:16:23.000 --> 01:16:33.000 Following up on one of the previous questions someone asked, can the amount of six PPD be reduced in tires while a safer alternative is developed. 01:16:33.000 --> 01:16:39.000 Like if they could contain, for example, 25% less six PPD. 01:16:39.000 --> 01:16:44.000 Who makes the decisions for about that. 01:16:44.000 --> 01:17:04.000 Yeah, that's a great question. And I've been I've been rolling up my sleeves on 6pvdq for a couple of years now since its discovery And I have not yet figured out the answer of who makes that decision. So it may be in the report somewhere in our conversation on the policy and law. 01:17:04.000 --> 01:17:25.000 But I think that that's being considered by all parties. I think that the brackets around that conversation are One, there's a lot of confidential manufacturing assessment of chemistries that goes into the products that are put on the market. So there's the product regulation aspects and the authorities that the EPA and other entities may have. 01:17:25.000 --> 01:17:34.000 Here and globally as well. And so that's kind of one end of that, the answer to that question. The other end is the requirement for safety. 01:17:34.000 --> 01:17:45.000 Tires have to meet safety standards to take cars on the road and keep us all safe in the rain and other conditions. And so that's also going to kind of drive, pardon the pun. 01:17:45.000 --> 01:17:50.000 What goes into the tire to make sure that it remains as safe as we need that tire to be. 01:17:50.000 --> 01:18:11.000 So between those two bookends, I don't know where we land on that question. And I think that that That is a really interesting one that I believe that the industry itself is looking at right now As this has become more and more of an issue, but I can't speak to that necessarily. 01:18:11.000 --> 01:18:16.000 In other ways. Of having six PPD. 01:18:16.000 --> 01:18:30.000 Reused. Tires are being recycled. Is creative ways to find an end use like being incorporated into roadways. Do you think roads constructed with recycled tires pose a higher risk for 6-PPD. 01:18:30.000 --> 01:18:41.000 Or could this be bound up during the road making process? 01:18:41.000 --> 01:18:50.000 I answered a similar question in the written answers, but in general, I think we don't really have much data yet. 01:18:50.000 --> 01:18:59.000 On this question. I think there's maybe like one study looking at rubber modified asphalt. 01:18:59.000 --> 01:19:07.000 And it showed that there weren't high levels coming off of the road, but that was just one study. 01:19:07.000 --> 01:19:12.000 And there's lots of different ways that you can incorporate tires into roads. 01:19:12.000 --> 01:19:26.000 So I think this is a really big, important data gap at this point in time. 01:19:26.000 --> 01:19:32.000 Jumping back to one of the questions that was answered 01:19:32.000 --> 01:19:49.000 Let's see. This goes… again into the studies, has the fate and transportation of six ppd groundwater been studied. Groundwater is obviously a pathway for humans but also salmonoids via base flow to streams. 01:19:49.000 --> 01:20:01.000 And I think that was covered a little bit. 01:20:01.000 --> 01:20:07.000 There's no comments on that. I'll keep going. Take a couple more questions. 01:20:07.000 --> 01:20:16.000 Any studies of runoff from roof shingles made of recycled tires. 01:20:16.000 --> 01:20:21.000 Not that I know of. Not yet. Another data gap. 01:20:21.000 --> 01:20:31.000 Stay tuned. This science moves pretty fast. 01:20:31.000 --> 01:20:50.000 I think one of the things to keep in mind as any of these products get asked about from roof shingles to like the rubber mats baristas stand on coffee, you know, coffee shops. There's additives in rubber everywhere. And so some of them are going to contain 6 ppd some of them are going to contain something else. 01:20:50.000 --> 01:21:19.000 Another one of the PVDs or some other anti-ose in it or anti-degranate. And so those each individual kind of consumer product is its own assessment. So the question really becomes if there is 6PBD in the consumer product Does it go through the environment to land in a place where it affects either a salmonid or an affected fish species or if we find human health data gaps, if we fill those data gaps on human health. 01:21:19.000 --> 01:21:40.000 Is there an exposure to somebody that's at risk or something that's at risk from the 6BDQ. And so for the hypothetical assessment of a roof shingle that may be full of 6 PBDQ, Is the runoff from that roof landing on a driveway that goes to a pipe that has no sort of mitigation SCMs between it 01:21:40.000 --> 01:21:54.000 And receiving water with a salmon. So that would be the assessment that goes into kind of questioning whether or not that that is an issue and and then how do you regulate? How do you work with? How do you mitigate from that product? So any given 01:21:54.000 --> 01:22:06.000 Product can lead to any one of these kind of trajectories through this plingo game of managing 01:22:06.000 --> 01:22:18.000 Thank you, Sean. I'll take like two more questions before we uh decide to wrap this up. What is known about how an organism eliminates this chemical from their body? 01:22:18.000 --> 01:22:25.000 Is it found in biosolids from wastewater plants? And that's going back to the septic tank question. 01:22:25.000 --> 01:22:45.000 So it depends on if the wastewater treatment plant is the combined plant or not. So if it is taking both stormwater runoff and treated wastewater and wastewater to treat Yes, we find 6PPD quinone in the biosolids. 01:22:45.000 --> 01:22:55.000 When it's not a combined system, I don't think we see it in the biosolids, but I'm not actually sure if that has been clearly studied. 01:22:55.000 --> 01:23:07.000 But there are some studies of wastewater affluent biosolids. And those are summarized in the guidance document. There's a table of all of the studies. 01:23:07.000 --> 01:23:12.000 In section four. 01:23:12.000 --> 01:23:31.000 Yeah, just to add what Ezra already said is I think biosolids are still a relative data gap and certainly understanding the difference of biosolids from combined sewer systems and separate sewer systems is is a big one. 01:23:31.000 --> 01:23:49.000 And I guess one more thing is, yeah, we don't know that much about how humans are absorbing and eliminating 6-pbd pronoun so when we're seeing the these compounds in the effluent and biosolids. 01:23:49.000 --> 01:24:07.000 Effluent and biosolids. We're assuming that it's from tires and road runoff rather than from being excreted, but we don't actually know that for sure. I don't think anyone has studied it. 01:24:07.000 --> 01:24:34.000 I'm going to jump to one more question. It looks like it's a quick are tires only commercial product that releases these two compounds in the environment Or are there other industrial products or commodity items that might be releasing these compounds into the atmosphere? 01:24:34.000 --> 01:24:41.000 So tires are not the only product. We have some evidence that it's in things like windshield wipers. 01:24:41.000 --> 01:25:00.000 But they seem to be the main product just because of how many tires are used and how much the use of tires directly ends up in release of tire particles and therefore these chemicals And I think, Kelly, you were going to add something as well. 01:25:00.000 --> 01:25:05.000 I wasn't necessarily, I think you did a great job answering that. 01:25:05.000 --> 01:25:14.000 But they have found that they have found some rubber gaskets in some faucets and plumbing fixtures. 01:25:14.000 --> 01:25:28.000 May have six BPD. Again, that's, as Ezra said, that's a very small quantity compared to the tire wear particles that are produced so Likely, that's a very minor source. 01:25:28.000 --> 01:25:44.000 But yeah, there are other things, particularly black rubber hoses, windshield wipers probably black rubber bumpers are likely to have six PPD. 01:25:44.000 --> 01:26:04.000 In them, but just it's that tire wear particle dispersion production and dispersion that really makes 6PPD and 6PD a huge cue a problem for tires. 01:26:04.000 --> 01:26:13.000 Thank you, Kelly and Ezra. All right, so I'll give a big thank you to our expert trainers for being here today and their contribution to the ITRC document. 01:26:13.000 --> 01:26:23.000 Clap to yourselves because we can't hear you. We'd like to hear back from you today, so please be sure to fill out the online feedback form that's linked in this last slide. 01:26:23.000 --> 01:26:32.000 When you fill out the feedback form and certify that you participated, it will give you a certificate of completion via email. 01:26:32.000 --> 01:26:38.000 If you need any further clarification on the answers or if you have any more questions. 01:26:38.000 --> 01:27:02.000 Feel free to email us at irc At ITRCweb.org and we will follow up with our trainers to get your questions answered. 01:27:02.000 --> 01:27:32.000 How do we…