An Earth Day lesson in ‘forever chemicals'

“When the first Earth Day was recognized, on April 22, 1970 , 20 million Americans – at the time, 10 percent of the total U.S. population – demonstrated in gatherings around the country to protest industrial developments that had led to serious human health impacts. And so began the modern environmental movement. The theme for Earth Day 2026 is “Our Power, Our Planet” – chosen to emphasize that everyone can further environmental progress. One wrong trying to be righted by researchers in UC Irvine’s Joe C. Wen School of Population & Public Health involves per- and polyfluoroalkyl substances – a massive group of synthetic chemical compounds that don’t break down easily. Known as PFAS, they are pervasive and persistent. The most studied of these “forever chemicals” indicate a toxicity that affects liver and thyroid function, and some have been shown to lead to cancer. In 2019, Scott Bartell , professor of environmental and occupational health, launched the UCI PFAS Health Study after receiving a grant from the Centers for Disease Control and Prevention to lead California’s contribution to a national multisite probe. In this episode of The UC Irvine Podcast, Bartell will share what drew him to the study of environmental contaminants, where PFAS are found and how people can decrease their exposure. He’ll also update what his team has learned about PFAS and what work is left to be done, as well as grade how the human race is doing in its efforts to take better care of the planet. “Walking in the Sky,” the music for this episode, was provided by Nico Staf via the audio library in YouTube Studio. To get the latest episodes of The UC Irvine Podcast delivered automatically, subscribe at Apple Podcasts or Spotify . Transcript Cara Capuano/The UC Irvine Podcast: From the University of California Irvine, I’m Cara Capuano. Thank you for listening to The UC Irvine Podcast. Our guest today is Scott Bartell, professor of environmental and occupational health, and vice dean of academic affairs for UC Irvine’s Joe C. Wen School of Population and Public Health. He’s also affiliated with the Departments of Statistics, Epidemiology and Biostatistics, and Health, Society and Behavior. Professor Bartell, thank you for joining us today. Scott Bartell: It’s my pleasure. Capuano: Each April we celebrate Earth Month, a global initiative dedicated to environmental awareness. You’ve committed your career to environmental studies, focusing these last 25 years on measuring human exposures and health effects caused by environmental contaminants. When people ask you what you do, how do you describe your work? Bartell: Well, like most University of California professors, I do a mix of research, teaching and service with a lot of the emphasis on the research. Personally, I’m very interested in characterizing how much exposure people have to contaminants in water, food and air. So, we can study whether or not people who have more exposure to those contaminants have worse health outcomes. And also helping regulatory agencies figure out what environmental interventions to prioritize in order to improve people’s health. I also serve as vice dean for our new School of Population and Public health here at UC Irvine, for which I oversee our academic programs serving over 1600 students ranging from undergraduates to doctoral students – and that keeps me pretty busy too. Capuano: What inspired you to make the examination of environmental contaminants your life’s work? Bartell: Well, I studied environmental sciences broadly as an undergraduate student, but got very interested in assessing human exposure and health risks when I learned that there was a Superfund site – the Aerojet Superfund site – under my parents’ house, essentially a contaminated groundwater plume – and this is sort of east of Sacramento in the Rancho Cordova/Gold River area. There were some debates about whether the contaminant levels in this contaminant plume were high enough to cause health problems, and I decided to probe that issue for my senior thesis at Berkeley. And then, found it so fascinating I decided to go on and continue to graduate school to learn more about how people answer those questions and study those questions. And then I ended up studying environmental health, and statistics and epidemiology in graduate school in the various graduate programs I went to, to sort of further that knowledge and understanding. I only started to get interested in PFAS, which I think we’re going to be talking about today, in the early 2000s, when a colleague at Emory University – where I first started my first professorship – approached me about joining the C8 studies of PFAS exposure and health effects in communities surrounding Parkersburg, West Virginia. A lot of my research effort since then has been focused on PFAS chemicals. Capuano: So, PFAS… Are you going to pronounce it or shall I try? Bartell: (Laughs) Capuano: Per- and polyfluoroalkyl substances… did I do all right? Bartell: That’s perfect. Yeah. But most of us in the field just say “PFAS” because it’s a lot of syllables to pronounce. Capuano: Well, thank heavens for that. Where are PFAS found? What are the most common sources? Bartell: Well, something everybody should understand about PFAS is that these chemicals don’t exist in nature. They’re entirely manmade and they’re produced by a relatively small number of companies. But those companies are large and have a huge reach. They sell their products to many other companies that use them to produce many products that are really useful. Things like Teflon, Scotchgard , paints, pesticides, firefighting foams, makeup. They’re used to treat clothing to make it waterproof. And that’s been going on for a long time with relatively little regulation or pollution control. So, unfortunately, now PFAS chemicals are detected in – by some estimates – half or more of U.S. water supplies and they’re found in nearly everyone’s blood. (Sighs) Capuano: Wow! That’s a big number: “half or more.” Bartell: Yeah. We’re still learning because they’re not monitored regularly – there’s no requirement for regular testing of water supplies. But starting around 2013, the EPA – U.S. Environmental Protection Agency – for the first time required that water systems serving more than 10,000 people around the country do a one-time test to just see if they were there. And that’s when we started to learn this was a much bigger problem than any of us had thought before. Capuano: Were any of those one-time tests then followed up? Bartell: Absolutely. Yes. And so, that led to a lot more interest in studying these chemicals, both in terms of their exposure – their presence in drinking water – and their health effects. But there’s actually another update – this going on right now. EPA has another sampling round where, again, water systems have to test for these chemicals. And the laboratory detection methods have gotten better since 2013. And so, we’re able to see now what’s happened in those water systems where it was detected but also finding it in other places where the levels were maybe low enough not to have triggered the detections in the previous round of sampling but are now popping up and showing us that there’s PFAS there. Capuano: Many chemicals elicit a certain fear response for people, especially when they start to think about how those chemicals can harm our bodies. What specific qualities of PFAS make them scary for folks? Bartell: Yeah. PFAS are a complex class of chemicals. There are over 10,000 different chemicals in this class, most of which haven’t actually been studied thoroughly. So, I’m going to try not to over generalize too much because we really just don’t know too much about most of the chemicals in this family. But they’re a concern because the small handful that are well studied are clearly toxic. For example, affecting commonly liver and thyroid function. And some are known or suspected carcinogens. PFAS are also persistent in the environment and can accumulate in our bodies over time, which increases our internal dose – out internal exposure to these – and our risk of health effects. And so, for all those reasons we’re concerned about them. And the other factor I think that contributes to making them scary is just that people are only recently learning about PFAS. A lot of people never heard about these chemicals prior to the last few years, and that can make them feel a lot more frightening. Capuano: Yeah – what you don’t know can be pretty terrifying. How can people decrease their exposure to PFAS? Are there some tips that you typically share or helpful habits that folks can adapt in their daily routine? Bartell: Yeah. So, the good news is that for PFOA and PFOS, which are two of the best studied PFAS chemicals with the most evidence of adverse health effects, the major US manufacturers and in Europe agreed to phase out production in the 2000s and 2010s for these few really bad actors and blood concentrations of those two contaminants have actually been slowly decreasing over time ever since then. The other good news is that 3M, which is one of the major manufacturers of PFAS chemicals, actually stopped producing all PFAS chemicals at the end of 2025, which is also very important action that will help reduce future exposures to people. EPA recently took action to set enforceable limits on PFOA and PFOS in drinking water for the first time. Those regulations won’t actually come into effect until 2031, though. So, I always tell people, if you have PFAS in your drinking water, you don’t have to wait until 2031 for the EPA requirements to kick in, in order to take action yourself to reduce your exposure. So, many home water treatment systems – for example, reverse osmosis systems or even just granular activated carbon, which is the common material used in water filters, like Brita filters and other brands, that you can put in water pitchers, or in refrigerators that often have water dispensers often have a water filter. And many of those filters are actually certified to remove PFOA and PFOS but actually can be effective for removing some of the other longer-chain PFAS chemicals that we’re concerned about. As long as you change the filters on time, and this is the big caveat. I know some people who sort of put that filter in the fridge, or don’t even realize it’s there when they buy a new fridge, ignore the little change filter light on their refrigerator, and eventually that filter, the PFAS will break through and start to affect the water again. And so, it’s really important to follow those instructions and change the filters on time. If you do that, they can be pretty effective at removing PFOA and PFOS. The other thing people can do is to avoid buying and using PFAS-containing products at home. There’s a couple in particular where we have good evidence that can make a noticeable difference in your blood concentrations. For example, having carpeting has been associated with 20-30% higher PFAS levels in your blood just because of the extent to which PFAS were used to treat carpeting for stain resistance. Applying waterproof treatments at home also can elevate your exposure or doing things like waxing skis at home. There are some efforts to try to remove PFAS from ski waxes – we know that people who’ve, you know, worked with ski waxes professionally tend to have higher PFAS levels in their blood. And there’s some evidence that people with healthier diets and eating more fruits and vegetables have lower blood PFAS concentrations. But ultimately, we really have to just clean up the food chain by restricting the release of PFAS chemicals into the environment if we want to reduce exposure, because diet seems to be, for most people, the largest source of exposure. Capuano: That’s a lot of helpful information. In 2019, the Centers for Disease Control and Prevention approved your grant proposal to lead California’s contribution to a multisite study on PFAS, which led to the launch of the UCI PFAS Health Study. How did your team conduct that study? Bartell: Well – along with the other seven sites around the country that were part of the multisite study – over a period of several years, we recruited hundreds of local participants here in Orange County, who lived in North Orange County communities with PFAS detections in the water supply, asking them to tell us about their residential and work histories, their water use, and any medical conditions they had. We also invited them to come to our clinic at the UCI Medical Center in Orange to give a blood sample and to do some additional tests. Meanwhile, we have collaborators at the UCI School of Engineering, led by Professor Russ Detwiler, who worked with Orange County Water District hydrogeologists and engineers to better understand how PFAS got into the groundwater in Orange County and to estimate how high the levels of PFAS contamination might have been going back over the last 20-25 years. Capuano: That’s pretty extensive. What did your team find? Bartell: Well, we’re still analyzing the enormous amount of data that were collected, but some of the key findings so far include learning that PFAS levels in people’s blood in Orange County were, on average, about 30 to 40% higher for people regularly consuming unfiltered tap water compared to those who primarily drink bottled water or filtered water – but that non-water sources of exposure, such as diet, still likely contributed more than water to overall exposure. We’re also looking at some of the health outcomes that we assessed in our study, in collaboration with the other sites, by pooling the data across all the sites in the study and finding some confirmation of what’s been reported before in the literature that people in our study had higher PFAS exposure levels also have slightly higher cholesterol levels, particularly LDL, which is unfortunately the bad cholesterol. And that’s consistent with some of these other studies in the literature, and we’re starting to think that PFAS really does cause this effect of higher cholesterol. On the other hand, we’re not seeing any evidence that people with higher PFAS levels in our study are more likely to have heart disease or obesity, and that’s good news, but those are two other health conditions that are sort of currently under debate as to whether they’re caused by PFAS or not. Capuano: What work is left to be done? It sounds like quite a bit. Bartell: So much. Yeah. We actually have a lot of other health conditions that we’re actively probing right now. I have a small army of doctoral students working on different analyses and papers using these data. And the other sites in the study are doing work as well along those lines. And there’s others that we haven’t yet started but still hope to investigate using these data. We sort of prioritized, starting with what we thought were sort of the most important health effects to begin with. But we actually asked about a broad set of conditions, and we took blood samples that allow us to look at immune markers, thyroid function, liver functions. So, there’s quite a bit more that we want to probe. We’d love to do long-term follow-up of these study participants also, to see how their health progresses over time. But unfortunately, our current study funding is nearly run out with no plans for continuation by CDC. So right now, we’re just focused on doing what we can with the data and the resources we have left, and then we’re going to be looking for alternative funding sources soon. Capuano: Well, fingers crossed those appear. Bringing it back to a bigger picture Earth Month question now: how would you rate the job the human race is doing on being more mindful to avoid putting contaminants into the environment? Bartell: I mean, that’s a (sighs)… that’s a tough question and a big, broad question. Overall, I think I would give us maybe about a B-. And let me explain that. There’s been a tremendous amount of progress since the first Earth Day in 1970. One example would be urban smog and air pollution. It’s much, much better controlled since then. I’d give us an A on that issue. I also think the Clean Water Act had a major impact. You might recall back around the first Earth Day, you know, rivers would occasionally catch on fire from all the pollutants that were being dumped in them building up to such high levels. And we haven’t seen anything like that for a long time in the U.S., so I think we’ve made a lot of progress there. We’ve made some progress on PFAS, as I discussed earlier in the interview, and other hazardous pollutants as well. But I think where we get a failing grade, unfortunately, is on carbon dioxide and methane. So, for example, atmospheric carbon dioxide levels have continued to march upwards every year and are now about 50% higher than they were set prior to the Industrial Revolution. They’re actually increasing faster now. CO2 in the atmosphere is going up at a faster rate than it was in 1970 at the first Earth Day. And the consequences of that for the entire planet are staggering. Capuano: Is that going to be your next contaminant that you study, or are you going to stick with PFAS for a while? Bartell: (Laughs) I’m probably going to stick with PFAS. I’m very interested in CO2 and other greenhouse gases because of the impact. And I’ve taught actually an undergraduate course in “Climate Change and Health,” so it’s a topic of interest, but I have my hands full already with PFAS, so I’m probably going to stick with that. Capuano: Indeed. It sounds like you do. What haven’t we discussed today that maybe you wanted to share in this conversation? Bartell: I think I’d just like to give a shout-out to my research team at UCI, to our study participants, to the CDC and our other funders, and to my collaborators and colleagues doing environmental health research around the country and around the world. None of this research really happens without that community of researchers, students, and study volunteers making it possible. And I’m just really grateful to be part of it. Capuano: Those kinds of partnerships are what really move public health along, aren’t they? Bartell: Yeah, they’re absolutely necessary. It doesn’t happen without it. Capuano: Thank you so much for joining us today, Professor Bartell. We’ve learned a lot. Bartell: Oh, my pleasure. Capuano: I’m Cara Capuano. Thank you for listening to our conversation. For the latest UC Irvine News, please visit news.uci.edu. The UC Irvine Podcast is a production of Strategic Communications and Public Affairs at the University of California, Irvine. Please subscribe wherever you listen to podcasts.

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