WEBVTT 00:00:00.000 --> 00:00:00.000 Thank you all who have joined so far to get us started, we will kick this off at the top of the hour. 00:00:00.000 --> 00:00:00.000 Plus, we have, uh… Attendees continue to join us. I'm going to run through a couple of quick housekeeping rules. 00:00:00.000 --> 00:00:00.000 To get us started, uh, we are recording today's training, and it will be offered on demand. 00:00:00.000 --> 00:00:00.000 Fluent for those not able to join us. The clue and training page also has the slides available for download. 00:00:00.000 --> 00:00:00.000 I will put that link in chat shortly. 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By TRC nor the U.S. Government warranty the material, nor endorse any specific products. 00:01:23.000 --> 00:01:33.000 On behalf of the Interstate Technology and Regulatory Council, welcome to today's training and overview of the tire-derived chemicals 6PPD and 6PPD quinol. 00:01:33.000 --> 00:01:36.000 My name is Nicole Henderson, and I will be your moderator. 00:01:36.000 --> 00:01:43.000 This training is an overview of the online guidance document. Produced by IOTRC in 2024. 00:01:43.000 --> 00:01:53.000 Today's training is sponsored by ITRC and is hosted by Cluin, the U.S. Epa Cleanup Information Network. 00:01:53.000 --> 00:02:04.000 I'd like to introduce our trainers today. All of them supported the development of the ITRC resources and volunteered their time to train additional audiences. 00:02:04.000 --> 00:02:15.000 Thank you to our trainers, and with that, I am going to turn this over to Kelly Grant with the California Department of Toxic Substances Control. 00:02:15.000 --> 00:02:18.000 To get us started. Thanks, Kelly. 00:02:18.000 --> 00:02:28.000 Thanks so much, Nicole. And thank you all for joining us today. Um, before we delve into, uh, talking more about 6PPD and 6PPD quinone. 00:02:28.000 --> 00:02:33.000 I want to give you a little introductory… some introductory thoughts, I guess. 00:02:33.000 --> 00:02:38.000 Um, our guidance document was really the first of its kind. 00:02:38.000 --> 00:02:46.000 Our team of experts worked diligently to compile the state of the science on 6 PPD and 6PPD quinone. 00:02:46.000 --> 00:02:55.000 And our training and the guidance document provide. Uh, in-depth background information, scientific findings. 00:02:55.000 --> 00:03:01.000 We identified data gaps and research needs as of March 2024. 00:03:01.000 --> 00:03:09.000 Uh, research is rapidly occurring to fill in those data gaps that we identified in the training and guidance document. 00:03:09.000 --> 00:03:14.000 And so, we encourage you to visit the resources that we call out in the document. 00:03:14.000 --> 00:03:21.000 To learn more about, uh, the current work that's going on. 00:03:21.000 --> 00:03:25.000 Next slide. So, as Nicole mentioned. 00:03:25.000 --> 00:03:29.000 Uh, we're going to give you an overview of these tire-derived chemicals. 00:03:29.000 --> 00:03:37.000 6 PPD and 6 PPD quinone. And in some cases, uh, we're going to highlight critical new information. 00:03:37.000 --> 00:03:45.000 Um, with that starburst that was on the last slide. Next. 00:03:45.000 --> 00:03:52.000 So, for decades, Coho in the Pacific Northwest have experienced massive mortality events. 00:03:52.000 --> 00:04:00.000 As they move through urban streams. Or urban centers, excuse me, to their natal streams to spawn. 00:04:00.000 --> 00:04:07.000 These mortality events are accompanied by distinct symptoms, including gasping at the water's surface. 00:04:07.000 --> 00:04:17.000 Finn splaying, and loss of equilibrium. These die-offs were found to coincide with storms and urban stormwater runoff. 00:04:17.000 --> 00:04:25.000 But despite the dire consequences for salmon populations. The chemical responsible remained elusive. 00:04:25.000 --> 00:04:31.000 While research focused on mitigation. Source control could not be addressed while the toxic. 00:04:31.000 --> 00:04:38.000 Compound remained undiscovered. Then, in late 2020. 00:04:38.000 --> 00:04:43.000 A research lab in Washington State made a breakthrough. They identified the compound. 00:04:43.000 --> 00:04:58.000 Responsible as 6PPD quinone. So, 6PBD and 6PPD quinone are contaminants of emerging concern, and as we've already mentioned, the science is rapidly evolving. 00:04:58.000 --> 00:05:07.000 So there are many data gaps and unknowns. The science and, uh, what we don't know will be discussed in each of these. 00:05:07.000 --> 00:05:19.000 Subtopics, as shown on, uh, this slide. And, uh, I'm going to kick us off with an introduction to 6PPD and 6PPD quinones. 00:05:19.000 --> 00:05:27.000 So, in, uh, 2011, a paper, uh, came out that documented a multi-year study to observe. 00:05:27.000 --> 00:05:36.000 Creeks in the Puget Sound watershed. With the goal of understanding pre-spawn mortality in coho salmon. 00:05:36.000 --> 00:05:45.000 Uh, they documented that up to 100% of coho salmon. Died before they could spawn in urban creeks. 00:05:45.000 --> 00:05:52.000 In female carcasses, there was greater than 90% egg retention, as shown here in this image. 00:05:52.000 --> 00:06:00.000 Indicating that they died before they could spawn. These mortality events were correlated with urban road runoff. 00:06:00.000 --> 00:06:12.000 And we're termed urban runoff mortality syndrome. But the toxic chemical responsible remained unknown. 00:06:12.000 --> 00:06:21.000 So scientists from academia and government. Worked to narrow down the toxic substances from all the chemicals in stormwater. 00:06:21.000 --> 00:06:29.000 Specifically to tire leachate. And then in 2018, a team of researchers at the University of Washington. 00:06:29.000 --> 00:06:37.000 Tacoma Center for Urban Waters. And Washington State University's Washington Stormwater Center. 00:06:37.000 --> 00:06:45.000 Started using high-resolution mass spectrometry. To identify the toxic contaminant contained in. 00:06:45.000 --> 00:06:51.000 Uh, tire wear particle leachate. And they identified over 2,000 chemicals. 00:06:51.000 --> 00:06:56.000 And through a series of fractionations. And approximately 3 years of work. 00:06:56.000 --> 00:07:08.000 The researchers discovered 6PD quinone in 2020. And this discovery was groundbreaking, and led to an all-hands-on-deck approach to. 00:07:08.000 --> 00:07:20.000 Prevent 6PPD quinone from reaching coho salmon. Later work showed that trout and char species also have a high sensitivity to 6PPD quinone. 00:07:20.000 --> 00:07:27.000 Next. What does 6PPD quinone, and where does it come from? 00:07:27.000 --> 00:07:34.000 Well, I mentioned they found an entire leachate, but it turns out that 6PPD equinone is not added to tires directly. 00:07:34.000 --> 00:07:44.000 Instead, a chemical called 6PPD is. 6ppd is used as an anti-ozonin and antioxidant in tires. 00:07:44.000 --> 00:07:49.000 To prevent cracking in rubber. As you can see, uh, in this image. 00:07:49.000 --> 00:07:58.000 It increases the longevity of tires. And is directly responsible for tires needing some of their federal safety standards. 00:07:58.000 --> 00:08:05.000 6ppd is assumed to be present in all tires due to its superior functionality. 00:08:05.000 --> 00:08:11.000 Uh, 6PMD is also found in post-consumer sources made out of recycled tires. 00:08:11.000 --> 00:08:21.000 Like, crumb rubber for turf fields and playgrounds. Rubber mulch for gardens, and rubber floor mats. 00:08:21.000 --> 00:08:31.000 So with 6PPD quinone is a transformation product of 6PPD. And it's formed when 6PBD reacts with ozone or other. 00:08:31.000 --> 00:08:38.000 Oxidizing compounds. 6ppd and 6PPD quinone have different chemical properties. 00:08:38.000 --> 00:08:43.000 That will be explained in more detail later in this presentation. 00:08:43.000 --> 00:08:54.000 Evidence suggests that the main source of both these chemicals. Uh, to the environment is tire wear particles. 00:08:54.000 --> 00:09:03.000 So the use of… oh, sorry, next slide. The use of 6PPD, uh, in tires began in the 1960s. 00:09:03.000 --> 00:09:12.000 And the mortality of coho salmon was first documented in the 1980s and continues today. 00:09:12.000 --> 00:09:23.000 Research initially focused on culturally important coho salmon. But in 2018, researchers started to look at other salmonid species. 00:09:23.000 --> 00:09:30.000 Yet at that point, the toxic agent was still unknown. And it wasn't until 2020 that 6PPD. 00:09:30.000 --> 00:09:36.000 Uh, quinone was discovered. And determined to be the cause of mortality in coho. 00:09:36.000 --> 00:09:45.000 Salmon. More recently, in 2023, the EPA granted a tribal petition. 00:09:45.000 --> 00:09:53.000 To have 6 PPD banned under, uh, Section 21 of the Toxic Substances Control Act. 00:09:53.000 --> 00:10:02.000 Then, in 2024, Washington State set the first aquatic life criteria value for 6 PPD equinone. 00:10:02.000 --> 00:10:09.000 That same year, EPA issued a non-regulatory, non-binding, acute screening level. 00:10:09.000 --> 00:10:16.000 To guide state and tribal water quality protections. 00:10:16.000 --> 00:10:23.000 So, when 6PPD was first discovered. And Coho were the only known sensitive species. 00:10:23.000 --> 00:10:30.000 6ppd quinone was kind of thought of as a regional concern, and you can see why in this map. 00:10:30.000 --> 00:10:37.000 Uh, this map shows the very limited distribution of coho in the U.S, with the native habitat shown in blue. 00:10:37.000 --> 00:10:45.000 And areas where they've been, uh, introduced. Shown in orange. Next. 00:10:45.000 --> 00:10:50.000 However, now we know that this is not just an issue for the Pacific Northwest. 00:10:50.000 --> 00:11:01.000 As sensitive species are found throughout the U.S. And globally. Since its discovery, 6PPD quinone has been found to be acutely toxic to. 00:11:01.000 --> 00:11:11.000 Um, rainbow trout, which is the same species as steelhead. Brook Trout, lake trout, and coastal cutthroat trout. 00:11:11.000 --> 00:11:18.000 Uh, these species are all ecologically or recreationally important throughout the entire U.S. 00:11:18.000 --> 00:11:26.000 6ppd quinone is now recognized as a global contaminant. And governments at various levels. 00:11:26.000 --> 00:11:34.000 Uh, both here in the U.S. And globally are increasingly recognizing the impacts of fixed PPPD, quinone. 00:11:34.000 --> 00:11:45.000 And moving toward regulation. Some tribal nations have treaty rights guaranteeing a right to fish and to manage salmon. 00:11:45.000 --> 00:11:56.000 The toxicity of 6PPD quinone to COHO and other salmonids. Threatens that right, and raises concern about nation-to-nation rights. 00:11:56.000 --> 00:12:00.000 And responsibilities. Tribal nations both. 00:12:00.000 --> 00:12:07.000 Uh, with and without treaty rights have expressed concern. For the impacts to salmon fisheries. 00:12:07.000 --> 00:12:16.000 In part. Because salmon are culturally significant to many tribal nations in the Pacific Northwest. 00:12:16.000 --> 00:12:21.000 Salmon are not only important for the diet of some tribal nations. 00:12:21.000 --> 00:12:26.000 But are a part of cultural practice, as shown here by a member of the Yakima Nation. 00:12:26.000 --> 00:12:32.000 Using traditional dip netting to catch, in this case, a Chinook salmon. 00:12:32.000 --> 00:12:38.000 Some tribal nations from this region even identify as salmon people. 00:12:38.000 --> 00:12:51.000 Elevating the significance of salmon well beyond a food source. In addition, salmon may be an important part of the economy to some tribal nations. 00:12:51.000 --> 00:12:58.000 Because spawning salmon are a key food source in the ecosystem, as well as to members of tribes. 00:12:58.000 --> 00:13:07.000 Some have expressed concern about secondary exposures from eating salmon. That may contain 6 PPD quinones. 00:13:07.000 --> 00:13:14.000 Salmon populations, uh, face concurrent threats. Including climate change, habitat loss. 00:13:14.000 --> 00:13:21.000 Migration barriers. And tribal nations commonly advocate for salmon protection. 00:13:21.000 --> 00:13:32.000 And I've always been involved in conservation efforts. And research into urban mortality runoff syndrome. 00:13:32.000 --> 00:13:41.000 Uh, and 6PPD quinone, and they continue to advance discussions. Research and policy. 00:13:41.000 --> 00:13:52.000 So, as I just said, tribal members have highlighted the concern for exposure to 6PPD and 6PPD quinone in both the ecosystem. 00:13:52.000 --> 00:14:02.000 And for people. And this conceptual model shows. Higherware particles that contain 6PPD, it shows that they can be transported. 00:14:02.000 --> 00:14:10.000 Through the air, or through stormwater runoff. The airborne particles can be inhaled. 00:14:10.000 --> 00:14:21.000 Uh, and can also deposit on surfaces, soils, and plants. 6ppd, quinone in surface waters can be ingested and absorbed by fishes. 00:14:21.000 --> 00:14:26.000 Uh, those exposed organisms can be ingested by humans or other species. 00:14:26.000 --> 00:14:33.000 And so research is ongoing to further define 6PPD quinones' environmental behaviors. 00:14:33.000 --> 00:14:41.000 Uh, exposures, and the potential for those exposures to cause. Adverse health outcomes. 00:14:41.000 --> 00:14:56.000 Research continues on how mitigation measures, like green stormwater infrastructure. Can potentially reduce 6PPD quinone, uh, transport to the ecosystem. 00:14:56.000 --> 00:15:03.000 So the guidance documents and our training cover what we knew as of Spring 2024. 00:15:03.000 --> 00:15:11.000 Uh, 6PPDE and 6 PPD quinone are, as we've said, emerging, uh, contaminants of concern. 00:15:11.000 --> 00:15:19.000 And so the research is going very quickly. Uh, science has progressed since this slide deck was developed. 00:15:19.000 --> 00:15:24.000 And again, we'll attempt to highlight some critical updates throughout the presentation. 00:15:24.000 --> 00:15:31.000 But data gaps still remain, um, and I'll highlight some of those now. 00:15:31.000 --> 00:15:37.000 Uh, so far, only a handful of aquatic species have been tested for toxicity to 6PPD. 00:15:37.000 --> 00:15:46.000 Six PPD quinone. Uh, the mechanisms by which it causes toxicity are still not fully understood. 00:15:46.000 --> 00:15:51.000 Uh, we know… Both chemicals have toxic properties. 00:15:51.000 --> 00:16:00.000 With potential relevance to humans. And that people are exposed to them through multiple, uh, environmental pathways. 00:16:00.000 --> 00:16:06.000 But the levels of exposure that can cause health effects in people is still unknown. 00:16:06.000 --> 00:16:17.000 So the overall human health impact is still uncertain. Environmental monitoring for the chemicals has become more common. 00:16:17.000 --> 00:16:21.000 But it's still not widespread. Therefore, understanding. 00:16:21.000 --> 00:16:30.000 Uh, of tire wear particles, 6PPD, and 6 PPD quinone. And their movement through the environment is limited. 00:16:30.000 --> 00:16:39.000 Until we have a better understanding of the physiochemical properties. Uh, the Fate and transport occurrence, and human exposures. 00:16:39.000 --> 00:16:47.000 We will not know the totality of 6 PBD quinones, social, and cultural impact. 00:16:47.000 --> 00:16:57.000 Stormwater management, uh, excuse me, stormwater best management practices. And source control efforts represent potential solutions. 00:16:57.000 --> 00:17:03.000 And work is being done to gather information needed to implement. 00:17:03.000 --> 00:17:08.000 Effective solutions. And with that short summary of data gaps. 00:17:08.000 --> 00:17:13.000 I am going to pass it to Ezra to tell you more about toxicity. 00:17:13.000 --> 00:17:19.000 Thanks, Kelly. Um… So, we'll jump right in. 00:17:19.000 --> 00:17:30.000 Um, in this section, we hope you will learn about which species are known to be sensitive to 6PPD quinone, what we do and do not know about 6PPD quinone's toxicity to aquatic life. 00:17:30.000 --> 00:17:40.000 And that ecological risk is a combination of the hazard or the toxicity of the chemical, and the exposure, or the concentrations in the environment. 00:17:40.000 --> 00:17:50.000 Finally, we will also talk about what we do and do not know about 6PPD quinone and its risk to human health. 00:17:50.000 --> 00:18:01.000 So, although 6Padaiquinone was only discovered about 5 years ago. There's been a considerable amount of toxicity testing, um, data developed for this compound. 00:18:01.000 --> 00:18:15.000 The main focus has been on acute lethality to fish. With limited, but increasing, chronic sublethal testing on fish and limited acute and chronic testing in other aquatic organisms. 00:18:15.000 --> 00:18:24.000 There's also pretty limited, but also increasing, data on terrestrial species, including humans, which we'll talk about in a few slides. 00:18:24.000 --> 00:18:35.000 Um, from the data gathered thus far, we know that there's variation both between different species and within a species, with clear differences in toxicity to different life stages. 00:18:35.000 --> 00:18:48.000 And importantly, we don't yet know the toxic mode of action of 6PPD equinone, or how various environmental factors and co-stressors, like temperature, may affect toxicity. 00:18:48.000 --> 00:18:52.000 So, what does the data that we've collected so far show? 00:18:52.000 --> 00:18:57.000 Um, of the species tested, salmonids, or salmon, trout, and char. 00:18:57.000 --> 00:19:07.000 Seem to be the most sensitive. And coho salmon are the most sensitive, with LC50s in the nanogram per liter, or part per trillion range. 00:19:07.000 --> 00:19:13.000 Um, this table is in micrograms per liter, which is a thousand-fold higher than nanograms per liter. 00:19:13.000 --> 00:19:19.000 The LC50 is the exposure concentration that is lethal to half the study population. 00:19:19.000 --> 00:19:26.000 And this is one of the lowest LC50s ever identified in aquatic organisms. 00:19:26.000 --> 00:19:32.000 For reference, 80 nanograms per liter, or .08 micrograms per liter. 00:19:32.000 --> 00:19:37.000 Is the equivalent to 4 drops in an Olympic-sized swimming pool. 00:19:37.000 --> 00:19:43.000 New data shows that coastal cutthroat trout are in a similar range of sensitivity. 00:19:43.000 --> 00:19:52.000 Um, to a coho. And these LC50s are below concentrations that are frequently measured in urban stormwater runoff. 00:19:52.000 --> 00:19:58.000 6ppd conone has been measured as high as 2.85 micrograms per liter in surface waters. 00:19:58.000 --> 00:20:05.000 And the onset of symptoms. Uh, after exposure often occurs within 90 minutes. 00:20:05.000 --> 00:20:14.000 Keep in mind that this is only acute toxicity, and it does not reflect the potential for sublethal effects. 00:20:14.000 --> 00:20:25.000 Um, so several others salmonid species have also been shown to be very sensitive, although not as extremely sensitive as coho and coastal cutthroat trout. 00:20:25.000 --> 00:20:31.000 And the color changes in this chart represent every order of magnitude change in the LC50s. 00:20:31.000 --> 00:20:40.000 So while not as extraordinarily lethal as coho, these LC50s are still considered to be highly toxic. 00:20:40.000 --> 00:20:45.000 Um, then there are other salmonids that show very low to no acute toxicity. 00:20:45.000 --> 00:20:59.000 From higher concentrations than have been measured in the environment. And once in my… once again, keep in mind that this is only acute toxicity and does not reflect the potential for sub-lethal effects on these species. 00:20:59.000 --> 00:21:14.000 You may have noticed that we've included the test duration for this data, and this is to show that these numbers are not necessarily directly comparable, because they mean that the fish were exposed to various concentrations of 6PPD quinone for different lengths of time. 00:21:14.000 --> 00:21:26.000 It's also important to think about, um, in terms of environmental exposures. So, fish are exposed during rain events and right after rain events, when the 6PP equinone washes into the surface waters. 00:21:26.000 --> 00:21:36.000 And those rain events and elevated 6PPD quinone concentrations may vary in time from just a few hours to several days. 00:21:36.000 --> 00:21:44.000 Um, outside of Solanaids, no fish have shown acute mortality at environmentally relevant concentrations. 00:21:44.000 --> 00:21:56.000 And 6VPD quinone also does not seem to be particularly toxic to Daphnids, or a growing list of invertebrates, like the amphipod hilella. 00:21:56.000 --> 00:22:07.000 Next slide. Um, so I mentioned earlier that we also know that sensitivity to 6PPD quinone varies not just among different species, but also within a single species. 00:22:07.000 --> 00:22:19.000 Depending on the age of the organism. So, for example, eggs seem to be generally less sensitive, possibly because the chorion, which is a protective membrane enveloping the embryos. 00:22:19.000 --> 00:22:35.000 Potentially mitigates the uptake to the embryo itself. Um, and then when we compare different independent studies, we also see age-dependent toxicity in coho salmon, with LC50s ranging from 41 nanograms per liter in newly feeding. 00:22:35.000 --> 00:22:44.000 Approximately 3 weeks post-swim-up hatchlings. To 95 nanograms per liter in fish over a year old. 00:22:44.000 --> 00:22:52.000 Surprisingly, the sensitivity to 6PPD quinone does not seem to be fully correlated with genetic relationships. 00:22:52.000 --> 00:22:59.000 Um, so this is a phylogenetic tree, which shows how various tested fish are related to one another. 00:22:59.000 --> 00:23:05.000 The pattern of branching reflects how the species evolved from a series of common ancestors. 00:23:05.000 --> 00:23:18.000 So species are more related if they have more recent common ancestor, such as a Chinook and coho salmon, and less related if they have a less recent common ancestor, such as zebrafish and coho salmon. 00:23:18.000 --> 00:23:27.000 And from this diagram, you can see that the closely related species do not necessarily share sensitivity or tolerance to 6PPD quinone. 00:23:27.000 --> 00:23:36.000 And this lack of relationship makes it difficult or even impossible, to predict toxicity to untested species with any sort of accuracy. 00:23:36.000 --> 00:23:50.000 Which is a real challenge for risk assessment. Um, so how does 6PPD quinone kill salmonids so quickly? We still don't know for sure, um, but there are now a few hypotheses. 00:23:50.000 --> 00:23:56.000 In early experiments on roadway runoff, before the identification of 6PPD quinon. 00:23:56.000 --> 00:24:09.000 Researchers found that the vasculature of the dying coho leaked. Plasma leaked from their gills, and also into their brains, indicating failure of the blood-brain barrier. 00:24:09.000 --> 00:24:19.000 Genes important for blood vessel architecture are also dysregulated in coho exposed to 6PBD quinone, which further supports this hypothesis. 00:24:19.000 --> 00:24:24.000 A second hypothesis is that mitochondrial dysfunction might be the mode of toxicity. 00:24:24.000 --> 00:24:33.000 In vitro testing of different rainbow trout cell lines, gill cells died after exposure to 6PPD quinone, while liver cells did not. 00:24:33.000 --> 00:24:40.000 And this correlated with oxygen consumption rates, which increased in the gill cells, but not the liver cells. 00:24:40.000 --> 00:24:50.000 And this is consistent with some cases of mitochondrial dysfunction. A third hypothesis is that toxicity is related to metabolism or biotransformation. 00:24:50.000 --> 00:24:58.000 With higher concentrations of native 6PPD quinone seeming to correlate with increased toxicity in several studies. 00:24:58.000 --> 00:25:07.000 Which suggests that survival may depend on an organism's ability to biotransform PPD quinones to less toxic metabolites. 00:25:07.000 --> 00:25:12.000 Um, the mode of action could be any of these hypotheses, or a combination of them. 00:25:12.000 --> 00:25:22.000 The bottom line is that we still need more research to really understand the molecular initiating event and how these effects follow from that event. 00:25:22.000 --> 00:25:28.000 Acute mortality is not the only toxic effect that could have population-level effects. 00:25:28.000 --> 00:25:33.000 But the sublethal effects of 6PPD quinone have really just started to be explored. 00:25:33.000 --> 00:25:39.000 Um, so the species listed on this slide are just the species that have been tested thus far. 00:25:39.000 --> 00:25:46.000 And a few recent papers have shown that 6PPD quinone has some developmental toxicity and delayed mortality. 00:25:46.000 --> 00:25:57.000 And several different solenins exposed as embryos and as hatchlings. And one paper has shown that 6PPD quinone exposure resulted in remodeling of the gills. 00:25:57.000 --> 00:26:03.000 Which reduced the surface area available for oxygen exchange, despite needing more energy. 00:26:03.000 --> 00:26:14.000 Which may disrupt the energy balance of the fish. And you can see, um, the difference in gill structure and the surface area between the control and 6PPD-exposed fingerlings. 00:26:14.000 --> 00:26:22.000 In these gill histology images. Another recent publication showed impaired swimming behavior in coastal cutthroat trout. 00:26:22.000 --> 00:26:30.000 Several papers have also shown a variety of sublethal effects in zebrafish, which are very tolerant to acute effects of 6PPD quinone. 00:26:30.000 --> 00:26:36.000 While some of these effects only occurred at exposure concentrations above those found in surface water. 00:26:36.000 --> 00:26:44.000 Several studies suggest that early life exposure to 6PPD quinone may cause behavioral changes at environmentally relevant concentrations. 00:26:44.000 --> 00:26:53.000 Which indicates that even tolerant species. May experience adverse effects, with the potential to affect populations. 00:26:53.000 --> 00:26:59.000 In general, it appears that 6PPD is much less acutely toxic. 00:26:59.000 --> 00:27:09.000 To fish than 6PD quinone, although its low stability and formation of transformation products make its toxicity difficult to study. 00:27:09.000 --> 00:27:18.000 And all of this research. Has, um, enabled development of water quality thresholds for 6PPD and 6PPD quinone. 00:27:18.000 --> 00:27:27.000 We'll talk about these more in the policies, regulations, and laws section of the webinar, but for now, just note that these are protective thresholds. 00:27:27.000 --> 00:27:40.000 So they're lower than the coho LC50. And coming back to our conceptual model, we're of course also interested in potential human health impacts, in addition to impacts to other species. 00:27:40.000 --> 00:27:48.000 We know there are a lot of potential routes of human exposure to tire particles that contain and release 6PPD and 6PPD quinone. 00:27:48.000 --> 00:27:58.000 As well as the chemicals themselves. So, we know 6PPD and 6PPD quinone are present in humans. 00:27:58.000 --> 00:28:05.000 On the left panel, we have summarized some of the body fluids of people where 6PPD and 6PPD quinone have been found. 00:28:05.000 --> 00:28:14.000 Over 10 peer-reviewed papers are now available, reporting one or both chemicals in human blood or urine samples of study participants. 00:28:14.000 --> 00:28:22.000 And since this slide was made, an additional report on breast milk confirms that both chemicals can get into human milk. 00:28:22.000 --> 00:28:29.000 6ppd quinone was reported in 2 studies of cerebrospinal… cerebrospinal fluid in human study participants. 00:28:29.000 --> 00:28:35.000 And, um, in addition, both chemicals were also found in a study of human umbilical cord blood. 00:28:35.000 --> 00:28:42.000 6ppd in amniotic fluid, and 6PPD quinone in the fluid around human ovarian follicles. 00:28:42.000 --> 00:28:53.000 From these studies, and studies using mouse models, we know that 6PPD and 6PPD quinone move to a wide variety of body tissues, including during pregnancy and lactation. 00:28:53.000 --> 00:29:01.000 After people are exposed. On the right side of the slide, we can also get a closer look at how the chemicals move in and through the body. 00:29:01.000 --> 00:29:15.000 Through studies of mouse models. And bioaccumulation in either people or mice is still not well understood, and we don't yet know what these observations mean for possible human health impacts. 00:29:15.000 --> 00:29:26.000 Um, this slide highlights some key hazard traits of 6PPD and 6PPD quinone relevant to humans, with some of the newly demonstrated toxicological endpoints shown in blue. 00:29:26.000 --> 00:29:41.000 Because 6PBDE has been in use for a while, we know a bit more about it. Um, evidence from rat and mouse studies and human volunteers suggest that longer-term exposure to 6PPD can lead to hepatotoxicity. 00:29:41.000 --> 00:29:53.000 This endpoint has been strengthened by recent studies. Uh, 6PPD can cause skin allergies, and it is classified by the European Chemicals Agency as a reproductive toxicant. 00:29:53.000 --> 00:30:02.000 Studies have shown that 6PPD can produce anemia in laboratory rodents, and we also know that 6PPD crosses the barrier between the blood and the brain. 00:30:02.000 --> 00:30:07.000 Emerging research in nerve cells suggest that 6PPD may have neurotoxic properties. 00:30:07.000 --> 00:30:12.000 And 6PPD is more active than the quinone in these studies. 00:30:12.000 --> 00:30:17.000 Neurobehavioral effects have also been observed in new studies of exposed mice. 00:30:17.000 --> 00:30:23.000 For 6PPD quinone, research is still emerging because the chemical is so recently discovered. 00:30:23.000 --> 00:30:34.000 Studies in mice have documented toxicity in multiple organ systems, with the strongest evidence for liver, reproductive organs, including the testes, ovaries, and endometrium. 00:30:34.000 --> 00:30:44.000 And intestines. Cellular barriers in the mouse intestine were disrupted after exposure, and intestinal toxicity is also seen in other model organisms. 00:30:44.000 --> 00:30:55.000 We don't have human data on this endpoint yet. And for both chemicals, scientists think that oxidative stress from metabolic pathways is a potentially important way the chemicals act. 00:30:55.000 --> 00:31:00.000 On the human and mouse systems. 00:31:00.000 --> 00:31:12.000 Um, so a large amount of research has been published on the toxicity of and exposure to 6PPD and 6PPD quinone in humans since we first created this training. 00:31:12.000 --> 00:31:20.000 Just showing how quickly this field is moving. It's not really practical to summarize all the new findings on one update slide, but here's a… 00:31:20.000 --> 00:31:30.000 A few high-level takeaways. Um, more studies in mice and other model organisms have been published that identify hazard traits in a wider range of tissues. 00:31:30.000 --> 00:31:37.000 Newly published studies of human volunteers suggest potential liver toxicity, ovarian, and other reproductive effects. 00:31:37.000 --> 00:31:47.000 But these effects are not yet confirmed. And oxidative stress has been identified as a potentially important mechanism of toxicity for both chemicals. 00:31:47.000 --> 00:31:55.000 There have also been numerous studies of human body fluids that have identified 6PPD and 6PPD quinone in new body compartments. 00:31:55.000 --> 00:32:06.000 Including blood plasma, amniotic fluid, placenta, cord blood, follicular fluid, more urine studies, and studies using hand wipes to assess dermal exposure. 00:32:06.000 --> 00:32:15.000 There have also been multiple studies published recently about the environmental occurrence of these chemicals in media that are relevant to exposure… to human exposure. 00:32:15.000 --> 00:32:25.000 Multiple publications now establish that both 6PPD and 6PPD quinone can be found in air, dust, soil, and drinking water. 00:32:25.000 --> 00:32:31.000 And some studies of foods, including fish, shrimp, and vegetables, report one or the other chemical. 00:32:31.000 --> 00:32:38.000 Rubber-containing consumer products, including those made from recycled tires, can also be an exposure source. 00:32:38.000 --> 00:32:49.000 Most environmental media studies are from China. Quantitative estimates of exposure are needed to reflect U.S. Exposures and confirm newly identified potential exposure pathways. 00:32:49.000 --> 00:32:57.000 Overall, we're confident that both 6PPD and 6PPD quinone have hazard traits of potential relevance to human health. 00:32:57.000 --> 00:33:05.000 Based on toxicity in multiple organ systems. Most people are likely exposed through multiple pathways. 00:33:05.000 --> 00:33:12.000 The critical uncertainty is whether these effects occur at the range of actual human exposure levels. 00:33:12.000 --> 00:33:18.000 So, to sum up, the toxicity of 6PPD and 6PPD quinone is an active field of research. 00:33:18.000 --> 00:33:29.000 With new papers coming out all the time. What we know so far is that 6PPD quinone is acutely toxic to coho and some other salmonids at very low concentrations. 00:33:29.000 --> 00:33:36.000 Although we still do not fully understand the toxic mode of action, or why some species are more sensitive than others. 00:33:36.000 --> 00:33:44.000 What we know so far is that, uh, wait. We know that sublethal exposures can also cause toxic effects. 00:33:44.000 --> 00:33:47.000 But we are only beginning to understand what those may be. 00:33:47.000 --> 00:33:56.000 And, uh, while we have a decent amount of data in salmonids, we still don't know that much about the effects on other aquatic and terrestrial organisms. 00:33:56.000 --> 00:34:02.000 Including humans. And in general, 6PPD seems to be less toxic in fish. 00:34:02.000 --> 00:34:08.000 Then 6PPD quinone, but it's difficult to study because of its chemical properties. 00:34:08.000 --> 00:34:17.000 And finally, we know that people are exposed to 6PPD and 6PPD quinone, and that both chemicals have the potential to induce toxic effects. 00:34:17.000 --> 00:34:23.000 However, we do not yet understand what that means for human health at current exposure levels. 00:34:23.000 --> 00:34:34.000 So now I'm going to hand it over to Rhea to talk about occurrence, fee, and transport, as well as measuring, mapping, and modeling 6PPD Coronel. 00:34:34.000 --> 00:34:41.000 Yeah, thank you, Ezra. Uh, yeah, in this section, we will discuss the sources of 6PPD and 6PPD quinone. 00:34:41.000 --> 00:34:47.000 And how they are released into the environment. And where the compounds have been detected. 00:34:47.000 --> 00:35:07.000 We will also highlight some of the data gaps, so there's many unknowns related to the fate and transport. 00:35:07.000 --> 00:35:16.000 Understanding the occurrence 6PPD and 6PD quinone necessitates a discussion of tire and road wear particles. 00:35:16.000 --> 00:35:22.000 These particles are generated by friction with the road and tires during normal driving conditions. 00:35:22.000 --> 00:35:29.000 Tire and roadwear particles are carried beyond the road surface via stormwater or other pathways. 00:35:29.000 --> 00:35:35.000 Such as air dispersion and deposition, and can enter aquatic or terrestrial systems. 00:35:35.000 --> 00:35:46.000 The occurrence and persistence of these particles in chemicals is still poorly understood with the fate and transport mechanisms that control occurrence. 00:35:46.000 --> 00:35:54.000 Varying among landscapes, geography, climate, and environmental conditions. 00:35:54.000 --> 00:36:04.000 Understanding the physical and chemical properties is important for discussions of fate and transport. 00:36:04.000 --> 00:36:10.000 An in-depth discussion of these properties is available in the ITRC guidance document and includes properties. 00:36:10.000 --> 00:36:18.000 That are measured in the environment and theoretical. Therefore, knowledge about these properties will continue to evolve. 00:36:18.000 --> 00:36:26.000 There are key properties that differ between 6PPD and 6PPD quinone, meaning they will behave differently in the environment. 00:36:26.000 --> 00:36:39.000 6ppd, in general, is more soluble in water, but 6 BPD equinone is still sufficiently soluble to be transported by water until it is captured by organic matter. 00:36:39.000 --> 00:36:45.000 6pd quinone is more stable in water, with a half-life of weeks versus. 00:36:45.000 --> 00:36:52.000 Less than a day for 6 PPD. More research is needed to understand the half-life. 00:36:52.000 --> 00:37:00.000 Under varying environmental conditions. One final aspect to note is that 6BB cridone is hydrophobic. 00:37:00.000 --> 00:37:18.000 So, provincially… preferentially binding to organic matter and can sorb to plastic containers. 00:37:18.000 --> 00:37:27.000 Since the discovery of 6-bitiquinone in 2020, there has been an increasing number of peer-reviewed studies about the occurrence of 6PPD. 00:37:27.000 --> 00:37:36.000 And 6PPD Clinone. Additional information can be found in the guidance document, especially tables 4-1 through 410. 00:37:36.000 --> 00:37:41.000 Where each media type has a table and a study summary. 00:37:41.000 --> 00:37:49.000 These studies are from peer-reviewed literature, and it is important to note they do not capture the preliminary monitoring efforts. 00:37:49.000 --> 00:37:58.000 By state, tribal, and local agencies. Or the significant increase in additional studies since March 2024. 00:37:58.000 --> 00:38:08.000 When interpreting data from the guidance document, considerations should be made in understanding that it is a regional-specific conditions that impact. 00:38:08.000 --> 00:38:19.000 The feed and transport. Is illustrated by the figure, there are currently limited studies on groundwater, drinking water, and road. 00:38:19.000 --> 00:38:36.000 Side soil, but storm water, surface waters, and dust. Have the most publications. We will highlight key areas of recurrence data focusing on the transport and exposure. 00:38:36.000 --> 00:38:45.000 We will first highlight surface water and stormwater, which are major mechanisms for transporting tire and road wear particles. 00:38:45.000 --> 00:38:54.000 6ppd and 6PPD quinone. Into receiving surface waters where concentrations of 6PD prenone could be observed. 00:38:54.000 --> 00:39:04.000 Above lethal levels for coho salmon. You will note a range in the reported concentrations, and the highest level of cisbequinone in surface water. 00:39:04.000 --> 00:39:16.000 2.85 micrograms per liter. Was published before there was a standardized method, and could be an overestimation of the concentrations. 00:39:16.000 --> 00:39:24.000 More studies are needed to understand how environmental conditions. Such as landscape, watershed, and storm characteristics. 00:39:24.000 --> 00:39:34.000 Affect the fate in transport. There's limited data about the… which storm water. 00:39:34.000 --> 00:39:42.000 And water treatment technologies are most effective at preventing. The transport of these particles and chemicals. 00:39:42.000 --> 00:39:56.000 In many places in the U.S, stormwater is not treated before discharging to surface waters. 00:39:56.000 --> 00:40:07.000 Higher-derived contaminants are washed into the water bodies during storm events, which may lead to a temporary peak in 6PD quinone concentrations. 00:40:07.000 --> 00:40:14.000 This storm hydrograph from Johanneson et al. In 2022 shows the black line. 00:40:14.000 --> 00:40:25.000 A rise and fall in concentration of 6-poppediquinone. Or peak concentration, versus the stormwater discharge in blue. 00:40:25.000 --> 00:40:32.000 One potent dose in a single storm is enough to cause acute effects in sensitive fish species. 00:40:32.000 --> 00:40:41.000 Even if average concentrations are very low. This is a key difference a 6BPD quinone relative to many other stormwater contaminants. 00:40:41.000 --> 00:40:47.000 A current study should take this into account as a single time point grab samples. 00:40:47.000 --> 00:40:56.000 May not represent an ecologically relevant concentration if you miss the peak. 00:40:56.000 --> 00:41:01.000 It is important to note that the peak in concentration can vary by river. 00:41:01.000 --> 00:41:11.000 Stream and watershed. In large rivers and watersheds, peak concentrations of 6BPD quinone may not be observed for hours after. 00:41:11.000 --> 00:41:15.000 The peak discharge. And so you can see that in the. 00:41:15.000 --> 00:41:23.000 Uh, Johannesen et al. Above. In smaller tributaries with high amounts of impervious surfaces. 00:41:23.000 --> 00:41:29.000 Peak concentrations may occur in the first hour, and are easy to miss. 00:41:29.000 --> 00:41:45.000 The greater the percent of impervious surface with. In the stream catchment, the more difficult it is to capture the pollutant peak. 00:41:45.000 --> 00:41:52.000 Stormwater and surface water transport. The tire and road wear particles. 00:41:52.000 --> 00:42:01.000 And, as shown in figure… in the figure, 6 PPPD and 6PPD quinone have been detected in river. 00:42:01.000 --> 00:42:10.000 Estuaries, coastal, and deep-sea sediments. There are also detections in roadside soil with observed biodegradation. 00:42:10.000 --> 00:42:17.000 And the models and measurements of 6PD and cisbequinone suggest ready binding to soil and organics. 00:42:17.000 --> 00:42:22.000 Additional studies are needed to understand the relationship between the suspended. 00:42:22.000 --> 00:42:29.000 Concentrations versus what is deposited onto the soils. And sinks to the sediments. 00:42:29.000 --> 00:42:37.000 Research is ongoing to fill data gaps. About the deposition, composition, biodegradation, and transformation processes. 00:42:37.000 --> 00:42:47.000 Or otherwise, the fate of the contaminant. Standardized methods for measuring tire and roadwear particles in water and sediments are challenging. 00:42:47.000 --> 00:42:58.000 N6pbid quinone may provide a proxy for tire drive microplastics. That could represent a continued source of 6PPD and 6PPD quinones. 00:42:58.000 --> 00:43:05.000 And microplastics themselves have their own issues. And concerns. 00:43:05.000 --> 00:43:11.000 Tire and roadward particles can disperse 6PPD and 6PPD quinone into the air. 00:43:11.000 --> 00:43:19.000 These particles exist as a variety of size fractions with the diagram illustrating how small the tire particles can be. 00:43:19.000 --> 00:43:28.000 The larger 50 to 90 micron particles in blue and green will be deposited near the roadways. 00:43:28.000 --> 00:43:34.000 While the smaller 2.5 to 10 micron particles shown in yellow and white. 00:43:34.000 --> 00:43:39.000 Can remain suspended in the air and be inhaled by organisms. 00:43:39.000 --> 00:43:49.000 Tire and road were particles increase with. Proximity to roadways, with 6PD and 6PD cranone being detected in particulate matter along roads. 00:43:49.000 --> 00:43:59.000 In outdoor air and indoor settled dust. More research is needed to better understand the airborne exposure pathways. 00:43:59.000 --> 00:44:14.000 In humans and in terrestrial and aquatic ecosystems. So we know much more about 6PPD and cisuquinone in water than we do air at this stage. 00:44:14.000 --> 00:44:20.000 6ppd and 6V quinone have now been identified in a variety of foods, such as. 00:44:20.000 --> 00:44:27.000 The examples you see here. Together. To European studies found one or both chemicals. 00:44:27.000 --> 00:44:41.000 In leafy greens, cabbage, carrots, onions, bell peppers, potatoes, pumpkins. Zucchini and tomatoes. More studies are needed to understand if levels of these chemicals in produce. 00:44:41.000 --> 00:44:50.000 And other foods are a concern for human health. A substantial knowledge gap exists regarding the presence of 6BPD quinone. 00:44:50.000 --> 00:44:56.000 And 6PPD with an edible fish tissues, and other aquatic biota consumed by humans. 00:44:56.000 --> 00:45:04.000 As well as whether these levels are sufficiently elevated to pose a risk to human health. 00:45:04.000 --> 00:45:14.000 Preliminary data from Washington Department of Fish and Wildlife and NOAA shows 6 PPD quinone in adult Chinook salmon fillet. 00:45:14.000 --> 00:45:19.000 But we don't know if these levels are a cause of concern. 00:45:19.000 --> 00:45:27.000 Preliminary studies in China have also shown these chemicals in edible aquatic species such as shrimp. 00:45:27.000 --> 00:45:38.000 Determining the concentrations in other aquatic food sources. And assessing the impact of various cooking techniques is important for evaluating any potential. 00:45:38.000 --> 00:45:46.000 Human exposure, and… establishing informed consumption guidelines. 00:45:46.000 --> 00:45:53.000 It is not yet known whether 6PPD and 6Pinone pose a bioaccumulation risk. 00:45:53.000 --> 00:46:01.000 But early indications are the bioaccumulation potential is relatively low to moderate. 00:46:01.000 --> 00:46:18.000 Direct toxicity probably poses the greatest ecological risk. But more research is needed to confirm bioavailability and bioaccumulation for both compounds in different species. 00:46:18.000 --> 00:46:24.000 Potential routes of human exposure from contact with consumer products may include. 00:46:24.000 --> 00:46:32.000 Dermal contact inhalation of particles. An incidental ingestion of particles. 00:46:32.000 --> 00:46:41.000 Depending on the product and usage patterns. Additional information is available in Section 4.6 of the guidance document. 00:46:41.000 --> 00:46:50.000 And includes many daily use common consumer products. 00:46:50.000 --> 00:47:02.000 Occurrence, fate, and transport studies have confirmed that 6PPD and 6PPD quinone are present in watersheds, urban runoff, sediment, air, dust, and snow. 00:47:02.000 --> 00:47:11.000 Confirming some of the routes of exposure in this conceptual model. 00:47:11.000 --> 00:47:17.000 In order to really understand 6CPD and the environment, we need to be able to measure it. 00:47:17.000 --> 00:47:40.000 We will now discuss measuring and mapping and modeling. 00:47:40.000 --> 00:47:48.000 In this section, we will highlight considerations for study design. Mapping tools that can assist in sampling locations. 00:47:48.000 --> 00:47:56.000 Aspects to consider for field sampling. And measuring lab… and laboratory analysis. 00:47:56.000 --> 00:48:01.000 And the modeling tools that can predict hotspots or concentrations of 6PPD. 00:48:01.000 --> 00:48:07.000 And 6BPD quinone. 00:48:07.000 --> 00:48:13.000 Measuring, mapping, and modeling are critical tools to understand the occurrence, fate, and transport of contaminants. 00:48:13.000 --> 00:48:20.000 Every contaminant has special considerations, and we will discuss adaptions to protocols and approaches. 00:48:20.000 --> 00:48:32.000 For 6PPD and 6 BPD quadone. Briefly, mapping tools help focus sampling and mitigation efforts, providing a visualization that is used to inform sampling locations. 00:48:32.000 --> 00:48:43.000 So many study designs start with mapping. These locations can then be sampled according to standard protocols or best-known practices. 00:48:43.000 --> 00:48:51.000 And sent to a laboratory for analysis. Data is then used to validate models to make predictions about occurrence. 00:48:51.000 --> 00:48:56.000 Studies continue to repeat this process to advance knowledge about the occurrence. 00:48:56.000 --> 00:49:02.000 Transport and risk. 00:49:02.000 --> 00:49:10.000 Mapping tools can help focus sampling and mitigation efforts by locating 6PPD and 6PPD quinone hotspots. 00:49:10.000 --> 00:49:18.000 And potentially vulnerable ecological populations. Key mapping layers that can inform sampling locations. 00:49:18.000 --> 00:49:31.000 Can include urban areas with high traffic locations. Watershed characteristics with precipitation data, and the habitat range of sensitive species. 00:49:31.000 --> 00:49:37.000 Impervious surface is one such. Layer that should be considered. 00:49:37.000 --> 00:49:48.000 Additionally information is available about mapping tools and data layers in Section 5 of the guidance document, so we… encourage you to check out Section 5. 00:49:48.000 --> 00:49:53.000 For more detail, as examples, we will highlight a state, federal, and risk mapping tool. 00:49:53.000 --> 00:50:12.000 That can be used to inform sampling. The first tool we are highlighting is the Washington Department of Ecology story map, a state-level mapping tool to identify potential hotspots of 6PD quinone near salmon-bearing water bodies. 00:50:12.000 --> 00:50:30.000 Which can help focus sampling efforts. A state-level view is available with areas of interest for 6PPD equinone sampling shown in dark blue. You can zoom to the streams of interest to see additional information in vulnerability school. 00:50:30.000 --> 00:50:39.000 Score. 00:50:39.000 --> 00:50:45.000 The U.S. U.s. Epa. Freshwater Explorer is another tool. 00:50:45.000 --> 00:50:54.000 Highlighting streams that are in close proximity to impervious surfaces, including roadways. 00:50:54.000 --> 00:51:01.000 When zooming in on a specific location, this mapping tool highlights in red and yellow streams that are near roadways. 00:51:01.000 --> 00:51:10.000 These locations could have high concentrations of 6PPD or 6Prinone during runoff events. 00:51:10.000 --> 00:51:18.000 And the Roads to Room paper. I developed a risk mapping tool that visualizes locations in Washington. 00:51:18.000 --> 00:51:26.000 That would be predicted to have high coho mortality. 00:51:26.000 --> 00:51:35.000 Or a heat map. Once locations of interest have been identified using desktop methods. 00:51:35.000 --> 00:51:41.000 Sampling can commence. Uh, after you've finished a project plan. 00:51:41.000 --> 00:51:50.000 General guidance for field sampling is available in Chapter 5 of the guidance document, recalling some of the physicochemical. 00:51:50.000 --> 00:51:59.000 Properties to consider when sampling. So, as a reminder, um, as we talked about Fate and transport and some of the information that Kelly covered. 00:51:59.000 --> 00:52:10.000 In the intro, 6PPD will be anticipated to have a lower detection frequency because of a half-life of less than a day, so it really doesn't stick around very long. 00:52:10.000 --> 00:52:16.000 A 6BD equinolone is hydrophobic and can sorb to plastic material, so that's something to. 00:52:16.000 --> 00:52:26.000 Consider, uh, when you're selecting your sampling equipment. So contact time should be limited with plastic materials during sampling and analysis. 00:52:26.000 --> 00:52:33.000 And glass materials are preferred. 6ppd and 6 buprenone can both interact with. 00:52:33.000 --> 00:52:40.000 Suspended solids as well. A sampling can be done with Grab, automated, and passive sampling. 00:52:40.000 --> 00:52:53.000 Selection of the sampling type and frequency will really depend on the goals of your project and available resources. 00:52:53.000 --> 00:53:04.000 Sampling in streams and during urban runoff. Provides environmentally relevant concentrations to be compared to the lab toxicity studies. 00:53:04.000 --> 00:53:15.000 And assess species-specific exposure risks. So, really looking at those environmentally relevant concentrations. Recalling the hydrograph that we showed previously. 00:53:15.000 --> 00:53:21.000 Um, the peak concentrations… the increase and then decrease in concentration throughout a storm event. 00:53:21.000 --> 00:53:31.000 Should be considered when planning sampling events for 6PPD quinone. Because 6pitiquinone is not a persistent organic contaminant in the water column. 00:53:31.000 --> 00:53:40.000 Sampling must be timed after the rainfall to capture the window of time with an elevated concentration. 00:53:40.000 --> 00:53:47.000 The exact timing of the rise in concentration varies by watershed. 00:53:47.000 --> 00:53:59.000 The hydrograph from the Don River is provided as. An example where the 6-BPD equinone concentration increases 8 hours after the start of the rainfall. 00:53:59.000 --> 00:54:05.000 And remains elevated. Elevated level for 32 hours. 00:54:05.000 --> 00:54:12.000 Sampling should be time to start after the rainfall to capture the rides in 6PPD Canon. 00:54:12.000 --> 00:54:20.000 This means that sampling in dry weather, so the days when it's nice to do field work, will. 00:54:20.000 --> 00:54:30.000 Miss the peaks of 6 BPD equinone. And other smaller watersheds at the time exposure, or the peak can only last, like, up to an hour or two, so… 00:54:30.000 --> 00:54:36.000 It really is easy to miss that 6PPD put on peak. 00:54:36.000 --> 00:54:47.000 One technique for sampling watersheds and stormwater is grab sampling. Uh, which needs to be timed appropriately with elevated 6PPD quinone concentrations. 00:54:47.000 --> 00:54:58.000 This approach captures a snapshot in time of the environmental concentrations, and recall that glass bottles are recommended for sampling 6 BPD quinone. 00:54:58.000 --> 00:55:07.000 And plastics should be avoided, especially for longer storage periods. 00:55:07.000 --> 00:55:13.000 Sampling in streams, and during. Oops, sorry. 00:55:13.000 --> 00:55:22.000 Autosampling is an advantageous sampling approach during storms. Because it can be programmed to collect discrete or continuous sampling. 00:55:22.000 --> 00:55:35.000 Over the course of the storm. Storms can happen at inopportune times, like evenings and weekends. They often do, and automated sampling can be programmed to capture the maximum concentration and measure. 00:55:35.000 --> 00:55:42.000 How long it remains elevated. While the grab sampling provides a snapshot. 00:55:42.000 --> 00:55:55.000 This technique is the equivalent of a short TikTok video. It can capture time composited or many discrete samples over the entire storm event. 00:55:55.000 --> 00:56:04.000 A longer-term sampling tool provides time-weighted average concentrations of contaminants. Is passive sampling. 00:56:04.000 --> 00:56:12.000 They can capture several storms, so it's more like a movie compared to the grab sampling. 00:56:12.000 --> 00:56:20.000 The passive devices are deployed in the field. And left for days to weeks. Many are relatively affordable, and some mimic. 00:56:20.000 --> 00:56:29.000 The bioavailability of contaminants. This is particularly useful for 6VPD quinone that is transported during storm events. 00:56:29.000 --> 00:56:34.000 And can persist for only hours to days in surface water. 00:56:34.000 --> 00:56:44.000 Before settling to the benthic environment or transported downstream. Preliminary investigations are underway to evaluate several different types of passive samplers. 00:56:44.000 --> 00:56:57.000 For 6BPD quinone and produce standard operating procedures. 00:56:57.000 --> 00:57:12.000 Currently available active and passive sampling approaches in air have also been investigated for 6PP and 6PPD quinone air sampling. 00:57:12.000 --> 00:57:20.000 After samples are collected, commercial, public, and research laboratories are available for the analysis of 6PPD. 00:57:20.000 --> 00:57:33.000 And 6PPD quinone in a range of environmental matrices. When selecting a laboratory, be sure it provides the analytical rigor required for project or program goals. 00:57:33.000 --> 00:57:46.000 Laboratory method accreditation… method detection limit, sample holding times. And quality control parameters should be reviewed to ensure data will meet the desired quality and reproducibility. 00:57:46.000 --> 00:57:56.000 Analytical method accreditation requirements vary by state organization and agency. Stormwater and surface water. 00:57:56.000 --> 00:58:03.000 Contain a range of suspended solids, and because 6PPD and 6-pupinone can sorb. 00:58:03.000 --> 00:58:09.000 To organic material, it is important to consider if the measurement is providing the. 00:58:09.000 --> 00:58:17.000 Dissolved aqueous concentration. Suspended solid concentrations or dissolved and solid concentrations. 00:58:17.000 --> 00:58:25.000 More research needs to be done on filtering of samples. 00:58:25.000 --> 00:58:33.000 For the measurement of 6PPD, a standardized or approved method is not available due to the instability of 6PPD. 00:58:33.000 --> 00:58:39.000 Laboratories have investigated the use of ozone scavengers to increase stability. 00:58:39.000 --> 00:58:47.000 And laboratory hold times, but they resulted in unstable conditions. For 6PPD prenone. 00:58:47.000 --> 00:58:52.000 A liquid from a graph. Chromatography, mass spectrometry, or gas… 00:58:52.000 --> 00:59:00.000 Hermata mass spectrometry are the common analysis methods, and provide an estimate of 6PPD. 00:59:00.000 --> 00:59:07.000 These are advantageous analytical techniques because of their adaptability to biotic and abiotic matrices. 00:59:07.000 --> 00:59:21.000 Environmentally relevant low-method detection limits, and suitability for targeted, semi-targeted. And our non-targeted screening. 00:59:21.000 --> 00:59:26.000 For the measurement of 6BPD quinone, an EPA draft method is. 00:59:26.000 --> 00:59:37.000 Available. Use of an approved method with dependable will depend on the goals of your study, but a standardized method reduces variability. 00:59:37.000 --> 00:59:46.000 That could occur between different techniques. Epa draft method 1634 recommends collection in amber glass bottles. 00:59:46.000 --> 00:59:53.000 A 14-day hold time pre-extraction, and a 28-day hold time post-extraction. 00:59:53.000 --> 01:00:01.000 And provides the total concentration of the dissolved. Plus total suspended solids. 01:00:01.000 --> 01:00:08.000 The USGS research method also demonstrates stability of cispuquinone during freezing. 01:00:08.000 --> 01:00:15.000 Which could increase sample hold times for laboratories. But your specific laboratory will work with you on the. 01:00:15.000 --> 01:00:26.000 On clarifying the hold times and storage. Research methods for other media have used a variety of extraction techniques coupled with. 01:00:26.000 --> 01:00:34.000 Lcms, NGCMS to provide concentrations in air-soil, sediment, tissues, food, and consumer products. 01:00:34.000 --> 01:00:45.000 Laboratories are working to expand capabilities. Washington State Department of Ecology has published a solids extraction procedure, while NOAA and the U.S. 01:00:45.000 --> 01:00:54.000 Geological Survey have published procedures for tissue extractions. 01:00:54.000 --> 01:01:02.000 Data generated from the mapping, sampling, and measuring can be used with established modeling tools to predict. 01:01:02.000 --> 01:01:12.000 The currents of 6PPD and 6PPD quinone. This can help to inform and focus sampling for hotspots near potentially. 01:01:12.000 --> 01:01:22.000 Vulnerable ecosystems and inform locations for mitigation. Epa tools for atmospheric fate and transport modeling have been applied to understand. 01:01:22.000 --> 01:01:33.000 The emission and transport of tire and road wear particles. The Velma tool was applied to 6PPD quadon to predict hot spots and types of green infrastructure. 01:01:33.000 --> 01:01:48.000 To reduce 6PPD quinone. 01:01:48.000 --> 01:01:55.000 Recently, other models are also being investigated, such as the U.S. Geological Survey, seldom. 01:01:55.000 --> 01:02:05.000 The stochastic empirical loading and dilution method. 01:02:05.000 --> 01:02:14.000 And measuring can also help validate these tools further. 01:02:14.000 --> 01:02:19.000 So, occurrence, fate, transport studies, along with the mapping and modeling tools. 01:02:19.000 --> 01:02:25.000 Have identified locations of potential hotspots for 6PPD and 6PPD quinone. 01:02:25.000 --> 01:02:34.000 All this data can inform the mitigations portion of the conceptual exposure model to identify locations for source control. 01:02:34.000 --> 01:02:39.000 And prioritize green infrastructure treatments. That can most effectively reduce. 01:02:39.000 --> 01:02:49.000 Contaminant loading to threaten aquatic habitats. I will now pass this to our next speaker, Sean, who will talk more about mitigations. 01:02:49.000 --> 01:02:55.000 Measure and solution. Thank you. 01:02:55.000 --> 01:03:04.000 Thanks very much. Um, we're gonna turn now to all of the fun stuff. How do we stop this problem from happening? Next slide, please. 01:03:04.000 --> 01:03:13.000 Uh, in this next section on mitigation, we're going to largely get a handle on this problem. We want to mitigate the sources and the impacts. 01:03:13.000 --> 01:03:18.000 Largely through alternative assessments and stormwater controls. It's important to note. 01:03:18.000 --> 01:03:24.000 Given the robust concerns about 6PPDQ impacts on aquatic life, starting with coho salmon. 01:03:24.000 --> 01:03:31.000 There's been quite a rapid response across all facets of mitigation. Stormwater management, stormwater treatment. 01:03:31.000 --> 01:03:52.000 Alternative assessments, all moving forward simultaneously. First up is assessments, or alternative assessments. We need to find an alternative to 6PPD. Nrc defines this process in a really fantastically complicated way, as a process for identifying and comparing potential chemical. 01:03:52.000 --> 01:03:59.000 And non-chemical alternatives that could replace the chemicals of concern on the basis of their hazards, comparative exposure. 01:03:59.000 --> 01:04:09.000 Performance and economic viability. Assuming that means we don't get anti-gravity cars anytime soon, or bamboo tires, we need to find an alternative. 01:04:09.000 --> 01:04:19.000 To 6PPD that does what it does in tires. Uh, they need to keep rubber safe, have toxicity testing, follow all the laws, and alternatives. 01:04:19.000 --> 01:04:26.000 Also, note, um, have to kind of grapple with all of the emerging science, the ongoing discovery of new information. 01:04:26.000 --> 01:04:33.000 And all the stuff that we just talked about and learned about over the last hour, all of that needs to be folded into alternative assessments. 01:04:33.000 --> 01:04:44.000 California and Washington have alternative processes going on right now. Uh, and the flowchart here from California is, uh, just detailing some of the steps in any product design. 01:04:44.000 --> 01:04:52.000 As we look at alternatives, we need to be thinking about alternatives across all of the different stages and pathways through production. 01:04:52.000 --> 01:05:04.000 Use and disposal. Alternatives need to be assessed for how they might fall out of attire at any given portion of this process, and it's also important to note that 6PPD. 01:05:04.000 --> 01:05:15.000 While it may be generated globally by a handful of companies, is used as an additive by tire companies around the world, many, many more companies around the world. 01:05:15.000 --> 01:05:25.000 In many, many different chemistries. And so there's lots of complexities behind, underneath, and around each of these stages in the design process. 01:05:25.000 --> 01:05:34.000 The complex undertaking. Um, it's a vital, important first step, is looking at alternatives, but it's one of many first steps that are all going on simultaneously. 01:05:34.000 --> 01:05:45.000 Next, we'll talk about source control. While we don't have any alternative, and while 6PBD is still in tires, and 6PVDQ is still leaching from tires, and tire and road wear particles. 01:05:45.000 --> 01:05:52.000 Source control is one of the two mitigation measures available. The other one is stormwater treatment. We'll talk about in the next slide. 01:05:52.000 --> 01:05:59.000 For source control, in the guidance document, there's a lot of information ITRC has pulled together discussing a variety of ways. 01:05:59.000 --> 01:06:08.000 To reduce generation of tire and road wire particles. Or, to limit the accelerated degradation of tires themselves, such as taking public transport. 01:06:08.000 --> 01:06:19.000 Um, walkable communities, teleworking, basically limiting single-car driving and the exposure of tires to roads, which is where they wear down, and then end up in our environment. 01:06:19.000 --> 01:06:30.000 Driver behavior outreach, um, uh, is also important, as certain types of driver, uh, driving can generate more tire wear, uh, particles, such as frequent or. 01:06:30.000 --> 01:06:42.000 Sudden acceleration and stopping. Sharp high-speed turns and hitting curbs. Just a way to remember this is to say that eating donuts at a bakery is a good idea. 01:06:42.000 --> 01:06:46.000 Making donuts with your tires in front of a bakery is not a good idea for the planet. 01:06:46.000 --> 01:06:52.000 There's a lot of emerging technologies also being looked at to capture tire wear particles from tires. 01:06:52.000 --> 01:06:59.000 Uh, this is being looked at as part of the microplastics universe as well, and so check out ITRC's great materials on microplastics, too. 01:06:59.000 --> 01:07:13.000 Lastly, stormwater control for source control involves street sweeping, for example, and that depends a lot on the how, where, when, and why of stormwater management, which we will turn to now. 01:07:13.000 --> 01:07:19.000 So we waited until slide 73 to talk about the first line of defense in a lot of communities where a lot of y'all are working on. 01:07:19.000 --> 01:07:31.000 This issue, and that's stormwater management. Planning stormwater control measures to manage 6PBD and 6PBQ, and the tire particles themselves as they move through our systems is vital. 01:07:31.000 --> 01:07:40.000 One of the first steps is finding out where those materials are moving, and the second step is designing treatments that can capture or treat, um, or control 6BBDQ. 01:07:40.000 --> 01:07:49.000 Generally, stormwater managers take an approach detailed here in this flowchart, these panels to the right of this great green stormwater. 01:07:49.000 --> 01:07:55.000 Rain Garden in Seattle. Uh, the photo from the Ship Canal, uh, here, right, not too far from where I'm sitting today. 01:07:55.000 --> 01:08:07.000 First step is assessing water quality. We heard about the mapping tools earlier, about where hotspots might be, the ways to look at river systems, uh, to check when you're going to see the highest levels of 6PVDQ in the waterways. 01:08:07.000 --> 01:08:17.000 The next is planning mitigation. What are you going to build? What control or treatment measures are you… are best for this system? Is it rain gardens, flow controls, sweeping? 01:08:17.000 --> 01:08:26.000 Um, the next is implementation planning. Uh, what funding city-county collaborations, cross-jurisdictional coordinations are needed to put into place all of those. 01:08:26.000 --> 01:08:42.000 Um, mitigation measures and stormwater controls. And the last box here is remediation, which I like to think of as also including everything from maintenance, operation, education, long-term funding, adaptive management, and replacement costs, all in that one little box. 01:08:42.000 --> 01:08:54.000 Called remediation. Fourth step in stormwater planning. So let's talk about stormwater treatment a little bit more. So there's lots of stormwater control measures that have been identified as having high probabilities of 6PDQ mitigation. 01:08:54.000 --> 01:09:00.000 See the full guidance document for more information, as well as a couple of the links that have already been shared in the Q&A. 01:09:00.000 --> 01:09:10.000 Uh, there's a lot of information out there, and it's all emerging, as we've mentioned a lot of times on this call, the science is evolving daily on this stuff. 01:09:10.000 --> 01:09:15.000 So check a lot of the partner websites and information we've shared in the Q&A for more information. 01:09:15.000 --> 01:09:24.000 Here's a few types of stormwater control measures. One is street sweeping. Again, the concept here is to keep tire wear particles out of the stormwater system. 01:09:24.000 --> 01:09:31.000 Early indications are that some types of street sweepers that are designed to do that may work as designed. 01:09:31.000 --> 01:09:39.000 Um, there's also flow control in the middle. Slowing down water and letting it soak into features like bioswales, ponds, or permeable pavement. 01:09:39.000 --> 01:09:48.000 May also keep tearware particles out of stormwater systems. And then last, on the right, is runoff treatment. Actually getting 6PBDQ out of the discharge. 01:09:48.000 --> 01:10:01.000 Running, for example, stormwater through a 60-40 sand-compost mixture can be one of the most effective ways of getting 6PBDQ to break down before it gets into streams and waterways. Recall that 6PPDQ. 01:10:01.000 --> 01:10:09.000 Loves holding on to organic material, so giving it an opportunity to do so is one of the best ways to get it out of the system. 01:10:09.000 --> 01:10:28.000 As with most of these, um, stormwater control measures, when you couple them all together, when you plan source control, flow control, runoff treatments, all as part of a comprehensive package that includes operations and maintenance and adaptive management, you're going to get the best results for the receiving waters. 01:10:28.000 --> 01:10:38.000 Uh, in 2022, for research, um, on the next slide, there was an effectiveness report, um, released by Washington Department of Ecology. 01:10:38.000 --> 01:10:48.000 Examining tons of these different approaches to stormwater management, or best management practices, looking at all of these aspects of stormwater control effectiveness. 01:10:48.000 --> 01:10:56.000 Um, stormwater control measures, again, that involve organics, have been documented again and again as being the best ways to get the chemicals out of the system. 01:10:56.000 --> 01:11:07.000 And as, you know, kind of a key takeaway from earlier is that this is an ongoing field with lots of investment, so there's tons of conversations going on right now. 01:11:07.000 --> 01:11:14.000 An ever-evolving guidance for where to go next in the best methods for best management practices. 01:11:14.000 --> 01:11:22.000 For controlling 6PBD. Uh, with that, some of the drivers of that research is our next section, which is policy. 01:11:22.000 --> 01:11:32.000 Regulations and laws. The last section of our run-through of 6PPDQ today, uh, and the goal of this section is to check in on some of the key legal issues surrounding. 01:11:32.000 --> 01:11:41.000 Both of these chemicals, 6PVD and 6PVDQ, and some of the things that are driving the research investment in BMPs and more. 01:11:41.000 --> 01:11:53.000 Next slide, please. Uh, there's lots of things driving it, just some of them are listed here. Uh, see Section 7 in the report for more details, but right at the top of the list is tribal treaty rights and tribes. 01:11:53.000 --> 01:12:03.000 They, for one, have nation-to-nation treaties and rights that can affect the entire legal landscape for 6PPD and 6PPDQ management, for salmon protection and stormwater control. 01:12:03.000 --> 01:12:11.000 Federally, there's lots of environmental laws that have relevance here. One is TSCA, Toxic Substances Control Act. 01:12:11.000 --> 01:12:19.000 Generally speaking, this is the law that controls chemical safety and use. There's an active petition regarding 6PBDQ that we'll touch on in a minute. 01:12:19.000 --> 01:12:27.000 Under Clean Water Act, uh, there's a lot that goes into Clean Water Act management. We've heard about it all day today. Stormwater control. 01:12:27.000 --> 01:12:37.000 Um, much of what we've talked about above in the mitigation section is governed through permits under the Clean Water Act. General permits, like municipal stormwater or individual permits like. 01:12:37.000 --> 01:12:44.000 From refineries or sewage treatment plants. Water quality criteria are set and enforced through the Clean Water Act. 01:12:44.000 --> 01:13:01.000 And many geographic programs and funds, non-point source pollution programs, research priorities, water quality planning are all developed, again, through the Clean Water Act, as is enforcement, governance, permitting, and science. Other laws also dovetail with 6PBBD and 6PBBDQ. 01:13:01.000 --> 01:13:07.000 We heard earlier about more human health exposure assessments and research that are going on, so Safe Drinking Water Act, for one. 01:13:07.000 --> 01:13:20.000 Uh, is… is there's a question mark as to… to where 6PBDQ falls into SIDWA issues. Another is the Magnuson-Stevens Fishery Conservation and Management Act, for example, on salmon habitat protection. 01:13:20.000 --> 01:13:28.000 An essential fish habitat. Not listed here is the Clean Air Act, so we just had a few slides about airborne deposition and PM. 01:13:28.000 --> 01:13:34.000 And tire wear particles moving through the air. Clearly, RICRA, uh, for tire waste management. 01:13:34.000 --> 01:13:42.000 Has some dovetails with 63BDQ, and then ESA, the Endangered Species Act, has been front and center for this conversation. 01:13:42.000 --> 01:13:49.000 From the start, given Coho's listed status, right when 6BDQ was first discovered five years ago. 01:13:49.000 --> 01:14:00.000 Uh, and the listed status of coho along the West Coast. This is not a definitive list of where and what jurisdictions cover, uh, 6BDQ and all these legal landscape. 01:14:00.000 --> 01:14:08.000 In all these statutes. This is just intended to highlight where some of the current regulatory and planning actions are currently happening. 01:14:08.000 --> 01:14:27.000 Next, the toxics petition. In 2023, there was a petition by three tribes to EPA asking to prohibit the manufacturing, processing, use, and distribution of 6PBD and tires. Uh, in September 2023, the affiliated tribes of Northwest Indians passed a resolution in support of this petition. 01:14:27.000 --> 01:14:35.000 And then, eventually, an advance notice of proposed rulemaking was issued, and a final rule requiring reporting and copies of unpublished. 01:14:35.000 --> 01:14:41.000 Health and safety studies, um, was, uh, entered in in December 2024. 01:14:41.000 --> 01:14:48.000 Um, a lot of the reporting for this was recently delayed, uh, till May 2026 by an action this past summer. 01:14:48.000 --> 01:15:02.000 Next slide. Under the Clean Water Act, we saw above, uh, that there are some screening levels that are non-enforceable, but are helpful in all of the planning measures for whether you're talking about permits or water quality plans or non-point source plans. 01:15:02.000 --> 01:15:10.000 Or the development of those heat maps and a lot of the assessment phase for stormwater management planning can be very, very helpful. 01:15:10.000 --> 01:15:16.000 So the aquatics, uh, toxic criteria screening levels, uh, have been in place for a while, especially. 01:15:16.000 --> 01:15:21.000 Since the, uh, the conclusion of the process to develop a validated method for detecting. 01:15:21.000 --> 01:15:27.000 6pbdq in stormwater, and again, Washington State was the first to adopt a numeric water quality criterion. 01:15:27.000 --> 01:15:38.000 For 6PBDQ, um, it notably was developed for freshwater acute, and so there was no 6PBDQ put in place in that most recent rulemaking. 01:15:38.000 --> 01:15:52.000 For chronic exposures, nor for marine waters, for salt water. Uh, so that state water quality criteria has been submitted to the EPA for its review and approval, but has been finalized at the state level. 01:15:52.000 --> 01:15:58.000 And again, uh, turning to alternatives assessment and some of the legal processes going on there. 01:15:58.000 --> 01:16:06.000 Um, we might be able to hear more about this in the Q&A later, but in California, through its Safer Consumer Products Regulation Program. 01:16:06.000 --> 01:16:20.000 Uh, the state has required an alternatives assessment. 75 manufacturers have completed the first stage, um, and have listed 17 possible alternatives. Final lists are due in August 2026, I believe, in California. 01:16:20.000 --> 01:16:31.000 And in Washington, the state program has been folding in assessment data, other sensitive species, and other ecosystem information into their alternative process that is ongoing as well. So stay tuned. 01:16:31.000 --> 01:16:36.000 Through both of those entities for information on alternatives coming up soon. 01:16:36.000 --> 01:16:46.000 So what's next? Um… largely, regulation often follows research. We tossed a ton of information at you today, some of which is already underlying. 01:16:46.000 --> 01:16:51.000 Petitions by tribes or other science has already informed water quality criteria establishment. 01:16:51.000 --> 01:17:00.000 But there's a lot more information that can help. Guide the planning processes for a lot of this stuff, the risk assessments for a lot of this, a lot of waterways. 01:17:00.000 --> 01:17:11.000 And so much more that has to go into reviews for human health exposure and some of those other statutes that were in gray on the slide… a couple slides ago, like Clean Air Act and Safe Drinking Water. 01:17:11.000 --> 01:17:19.000 Much of this has already begun, like stormwater permits have been issued that require mitigation measures, testing of discharges. 01:17:19.000 --> 01:17:26.000 And retrofits to existing stormwater infrastructure. And as more information unfolds, so too will the regulations permits. 01:17:26.000 --> 01:17:34.000 Programs at state, federal, and local levels. Thank you. 01:17:34.000 --> 01:17:43.000 Sean and trainers, thank you so much. Pine 83 here is just an overview of the guidance document, where you'll find it. 01:17:43.000 --> 01:17:54.000 Uh, and some of the component sections in the navigation. But I want to thank all of our expert trainers for being here today, and for their contribution to the ITOC document. 01:17:54.000 --> 01:18:01.000 Please remember to visit the course training page on Cluin to find speaker bias, contact information. 01:18:01.000 --> 01:18:11.000 The slides from the course. And a cumulative question and answer summary document from all of our courses that we have hosted live. 01:18:11.000 --> 01:18:16.000 Um, at this time, I really want to thank everybody for their participation. 01:18:16.000 --> 01:18:26.000 There is a feedback form that you can complete, and at the bottom right, there's a box to certify that you participated. 01:18:26.000 --> 01:18:30.000 And then that will trigger an email to be sent to you. 01:18:30.000 --> 01:18:38.000 Uh, with your certificate of completion. Thank you. 01:18:38.000 --> 01:18:43.000 And with that, I think I'm going to ask our, um, panelists to come. 01:18:43.000 --> 01:18:58.000 Back out and see if there's any questions that we want to… talk through, we've answered a lot of questions. I just alluded to the fact that we will have a compilation of the question and answers online. 01:18:58.000 --> 01:19:06.000 Um, at the course training page. For everything that has been asked throughout the numerous times we've hosted this training, but… 01:19:06.000 --> 01:19:18.000 Um, we have about 10 minutes left, so with that, trainers, were there any questions that came through that you'd like to speak to directly here for the audience? 01:19:18.000 --> 01:19:30.000 Thanks, Nicole. Um… I accidentally told, uh, Ken Scally that I would answer a question live, although I think Tanya addressed it, but we did have a couple of questions about. 01:19:30.000 --> 01:19:38.000 Uh, routes of human exposure. And I just want to emphasize here that that research is ongoing. 01:19:38.000 --> 01:19:44.000 Uh, we don't have, uh, clear exposure pathways that, uh, have. 01:19:44.000 --> 01:19:52.000 Are definitively linked with exposure. I think Ezra said that there's probably multiple routes of exposure. 01:19:52.000 --> 01:20:03.000 Including inhalation of. Particulate matter… entire particulate matter, as well as consumption of fish, uh, that may be contaminated. So. 01:20:03.000 --> 01:20:11.000 There's an app, or vegetables that are contaminated. So, uh, there's a variety of potential routes of exposure. 01:20:11.000 --> 01:20:22.000 Uh, and we still need more research to understand those. But just, again, to emphasize, we don't understand whether those, uh, exposures are of concern yet. 01:20:22.000 --> 01:20:33.000 So, uh, we also need, uh, more information, more research there to really understand that concern. 01:20:33.000 --> 01:20:44.000 Yeah, that's great, Kelly, I appreciate you. Responding to that verbally. We are getting a couple of new questions in the Q&A, um, while we're having this conversation, so if any of them. 01:20:44.000 --> 01:20:49.000 Or… you can just… Easily to speak through, we can… 01:20:49.000 --> 01:20:51.000 Jump right over those. 01:20:51.000 --> 01:20:58.000 So, I can answer Amy's question, or I guess… give Amy a non-answer to her question, which is that we really don't know. 01:20:58.000 --> 01:21:07.000 Um, we know that tires are very complex products that have a lot of different… and release a lot of different chemicals. 01:21:07.000 --> 01:21:12.000 And that many of those chemicals are toxic to a variety of different. 01:21:12.000 --> 01:21:19.000 Organisms, including humans, but we really have very little understanding of potential for cumulative effects. 01:21:19.000 --> 01:21:27.000 That's true, kind of. As a baseline for all toxicity research at this point, like, we're really… 01:21:27.000 --> 01:21:42.000 Very much still in a world where we think about chemicals one by one individually, and don't think that much about cumulative effects, so… Um, we don't know. I will say, also, that, um, before the discovery of 6PPD quinone, there was a lot of work. 01:21:42.000 --> 01:21:48.000 Done on toxicity of. Stormwater runoff more holistically, and that… 01:21:48.000 --> 01:21:54.000 Kind of, by definition, includes these other, um, tire wear pollutants as well, and we. 01:21:54.000 --> 01:21:58.000 Saw a lot of, um, the same effects that we're seeing. 01:21:58.000 --> 01:22:04.000 From 6PB equinone, so it's hard to say what was being caused. 01:22:04.000 --> 01:22:20.000 From 6PP to Dequinone by itself versus this combination of chemicals, but… that it's… it's really a huge data gap in the toxicity world at this point in time. 01:22:20.000 --> 01:22:28.000 Thanks, Ezra, and I guess a reminder that the ITRC guidance document was the first of its kind, as Kelly said. 01:22:28.000 --> 01:22:38.000 Um, it did kind of… stop compiling information as of March 2024, um, per Kelly's introduction, and was published in September 20th. 01:22:38.000 --> 01:22:45.000 24, so a reminder. To continue to go out and find new sources of information, but… 01:22:45.000 --> 01:22:53.000 Certainly the ITRC guidance argument is amazing. First step to compiling the information. 01:22:53.000 --> 01:22:55.000 Uh, some other questions. In years. 01:22:55.000 --> 01:23:03.000 Yeah, I'll… I'll jump in here on one of the questions, or 10 of the questions on crumb rubber and artificial fields and turf. 01:23:03.000 --> 01:23:15.000 Um, but before I turn to that, one of the threads, I think, through some of these questions is about the complexities, and so I noticed there was an answered question about how potholes and roads can lead to tire wear problems. 01:23:15.000 --> 01:23:20.000 And I think that, you know, just as we said during the testing phase about how. 01:23:20.000 --> 01:23:33.000 An assessment of your water course and where the stormwater is coming from, and how much is impervious, and how… what your channel dynamics are inside the receiving water, where the salmon streams are going, where the affected fish are going. 01:23:33.000 --> 01:23:42.000 That's… that complexity, uh, has to be taken into account. The same thing is true with the sources and the stormwater control, and so the complex… how your roads are designed and built. 01:23:42.000 --> 01:23:49.000 How your curbs are designed and built, the number of electric vehicles and buses and heavier vehicles that are generating more tire wear particles. 01:23:49.000 --> 01:23:56.000 So there's just as much 3- and 4-dimensional complexity for the planning of the things on the land side as there are with the water side. 01:23:56.000 --> 01:24:00.000 And I think that that kind of folds into the question on crumb rubber and synthetic turf. 01:24:00.000 --> 01:24:07.000 So many tires go into fields. My 6-year-old plays on a giant one made out of, you know, former tires. 01:24:07.000 --> 01:24:22.000 And, uh, it is, you know, I like to think of it as a pile of tires. It is a pile of tires. And… you know, I have concerns about having my kids play on a pile of tires if it's in a wetland, and I have concerns about them playing in a pile of tires. 01:24:22.000 --> 01:24:28.000 On the sports field, and I think that there's conversations going on right now about just exactly what. 01:24:28.000 --> 01:24:36.000 Um, all the alternatives are for chrome rubber fields, how do we get, you know, how do we look at the stormwater impacts, the inhalation impacts, the exposure impacts from. 01:24:36.000 --> 01:24:54.000 Touching it and rolling around on it. That happens on a lot of these artificial turf and playgrounds. I think that they can also be a source, just like any other pile of tires, for things falling off the side of them. A lot of fields are designed to shunt water away, so there's no ponding on a field, so that it remains springy and dry. 01:24:54.000 --> 01:25:02.000 Where does that water go? So, just like a lot of other facilities have to do assessments as to, you know, where does the waste from this facility fall off. 01:25:02.000 --> 01:25:11.000 The facility, and where does the stormwater drain out of the facility, and what stormwater controls, BMPs, and other sort of, kind of, pollutant control. 01:25:11.000 --> 01:25:22.000 Mitigation measures do we need to instill for these sites, including alternatives assessment and elimination of risk exposure. So, all of those things, kind of, the conceptual things that you would do for any. 01:25:22.000 --> 01:25:32.000 Sort of industrial site or commercial site. Looking at sources of pollutant, whether those are chrome rubber bits or things rolling off the site, or things draining off the site. 01:25:32.000 --> 01:25:40.000 Would go into assessments of playfields, I believe. Moving forward. 01:25:40.000 --> 01:25:51.000 And just to echo what Sean said. Um, I think that applies to rubber-modified asphalt as well. There's a question somewhere down here… sorry, I lost it, um… 01:25:51.000 --> 01:26:00.000 About, uh… thinking about, uh, 6PPD quinone coming from rubber-modified asphalt, and there's. 01:26:00.000 --> 01:26:10.000 A couple studies, uh, some of those. Um, have suggested that, uh, rubber-modified asphalt might be a sink for 6PPD quinone. 01:26:10.000 --> 01:26:20.000 But I think, uh, even the authors of the paper said we need a lot more research to understand how that might work over different conditions, uh, different. 01:26:20.000 --> 01:26:29.000 Types of, uh, roads, and so… Um, what Sean said still applies to, uh. 01:26:29.000 --> 01:26:38.000 That condition as well. And then I was gonna tackle the question about, uh, Bass perch or walleye. 01:26:38.000 --> 01:26:46.000 And as far as I know, uh, only salmonids have been found to have any toxicity to 6PPD. 01:26:46.000 --> 01:26:55.000 Quinone, um, several species are, um. Sensitive to 6PPD, the parent compound. 01:26:55.000 --> 01:27:06.000 Uh, but at much higher thresholds of toxicity. So, usually it's… Uh, about 4 orders of magnitude, uh. 01:27:06.000 --> 01:27:13.000 Less toxic, I guess, than 6BPD quinone. So, I hope that answers your question. 01:27:13.000 --> 01:27:23.000 And I'll say, too, another question here on permeable pavement. And I think that one of the things to note is that there's a lot of… 01:27:23.000 --> 01:27:29.000 You know, I think movement for 20 years in the low-impact development world and the stormwater control measures. 01:27:29.000 --> 01:27:37.000 A lot of the solutions to other stormwater problems are being evaluated, given 6PPD. 01:27:37.000 --> 01:27:42.000 Q and 6PBD and tire wear particle awareness now that's been growing in the last 5 years. And so. 01:27:42.000 --> 01:27:49.000 I think one of the things that I've heard on things like porous pavement is they can get clogged with tire wear particles, and so just like anything else. 01:27:49.000 --> 01:28:09.000 Um, you know, operations, maintenance, ongoing adaptive management is key to understanding what pollutant you're trying to control for. So there are… there's no… Uh, there's no single thing that's gonna solve everything. Almost everything has to be designed for your system and its use, and have that essential operations and maintenance component. 01:28:09.000 --> 01:28:10.000 Thanks, Sean. 01:28:10.000 --> 01:28:15.000 Mike, I can, uh, jump in and take, uh, Terry's question really quick before we go, if we have enough time. 01:28:15.000 --> 01:28:16.000 Go for it. 01:28:16.000 --> 01:28:26.000 Um, about the… whether there's studies being done in Arctic regions. Uh, there are a couple papers looking at snowmelt in Canada. 01:28:26.000 --> 01:28:34.000 And that can be found, um, in our chapter 4 of the ITRC guidance document. 01:28:34.000 --> 01:28:39.000 But more studies need to be done for understanding the snow melt. 01:28:39.000 --> 01:28:41.000 Pathway. 01:28:41.000 --> 01:28:52.000 Excellent. Well, thank you so much. In the interest of all of our attendees' time, I will ask that if the trainers have a couple minutes to write written responses back. 01:28:52.000 --> 01:28:53.000 Um, to any open questions, please feel free to do that. 01:28:53.000 --> 01:29:01.000 That way, we'll get it captured into the compiled question and answer summary that will be posted as part of this final archive. 01:29:01.000 --> 01:29:11.000 Um, but a big thank you again, mostly to our speakers today for their time and energy. Really appreciate everything you have done over the past 3 years to support. 01:29:11.000 --> 01:29:24.000 Um, the ongoing communication about 6PD. And thank you to the attendees for today. We had an amazing crowd, a lot of questions were asked and answered. I hope you were able to. 01:29:24.000 --> 01:29:28.000 Take a look at those as they were put through the chat. 01:29:28.000 --> 01:29:34.000 Um, and finally, a reminder that I have posted the link to the feedback form. 01:29:34.000 --> 01:29:47.000 Um, we do look for your feedback. We take it into account. Most importantly, for many of you, as you get to the bottom of the feedback form in the bottom right, there is a small box that says that you certify you participated today. 01:29:47.000 --> 01:29:53.000 And that will trigger the email to be sent to your inbox, um, with the certificate of completion for the course. 01:29:53.000 --> 01:30:23.000 Thank you, everybody, for your time and attention. Speakers, again, thank you for any last-minute answers to questions, and with that, we will end the webinar. 01:33:01.000 --> 01:33:31.000 All right, again, thank you all. The webinar has ended. Um, we have finished responding to questions. I will be closing the webinar.