‘We can’t recycle our way out’

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Saturday, October 1, 2022

This piece was originally published by InvestigateWest. When dealing with the life cycle of plastic, hundreds of solutions await, from alternative bioplastics that might be able to degrade themselves through the magic of fungus, to complex chemical recycling that can break plastics down to become other petroleum products or to be rebuilt good as new But as promising as chemical recycling and next-generation plastics may sound, experts also say some of the most realistic solutions to plastic pollution involve eliminating it from packaging as much as possible. Decision-makers are asking: How can manufacturers design their plastic packaging to be recycled more easily after consumers are done with it? Should packaging all be the same color of plastic to avoid dye-based contamination in recycling processes? Could markers on different types of plastic help imaging robots at sorting facilities do their jobs better when diverting containers by type? Which products could avoid using plastic altogether? Currently, the vast majority of plastic recycling is done by mechanical methods. First, post-consumer plastics are divided by number; for example, the PET plastic or polyethylene terephthalate commonly used for beverage bottles needs to be separated from the HDPE plastic (high-density polyethylene) that’s often used for laundry detergent containers. Each group is then often shredded and melted into pellets that can get remelted and formed into new packaging. Or different plastics can be repurposed into boards for outdoor decks or processed into fibers for carpets and clothing.  But because heat can degrade the polymer chains (strings of repeating molecules) in plastic, there are limits to the number of times plastic can be “recycled” in the truest sense of being made into a new product. With those limitations in mind, many people, from those working for the largest oil and chemical manufacturers (think BP and Dow) down to individual entrepreneurs, are experimenting with chemical recycling as a potential way to recycle even more plastic. Less than 10 percent of the stuff actually gets recycled, but chemical recycling offers the promise of rebuilding the molecule chains that are broken down with heat, as well as the possibility of converting plastics into fuels and other compounds. Whether some of the newer chemical recycling proposals will actually succeed is a question. Common constraints include the high costs of building and powering processing facilities, the purchase of expensive chemicals, and the challenge of reliably sourcing materials uncontaminated with food scraps, dyes, or other types of plastic or garbage. Other concerns center on the greenhouse gas emissions of the chemical recycling process and, in the case of turning plastics into fuels, burning the end products, and whether those climate costs are less than those caused by creating virgin plastic. Meanwhile, innovators of all ages are developing plastic alternatives made from things like fish skin, vegetable starches and other biodegradable substances that offer the promise of rapid decomposition when disposed of properly, a sharp contrast with the thousands of years that traditional plastics may linger in the environment.  As people figure out whether chemical recycling or plastic alternatives can prevent plastic pollution — which has already tainted air, water, and land around the globe — local governments around the country are still getting a grasp on the recycling options that already exist. Washington state’s wakeup call came about five years ago when China stopped accepting highly contaminated bales of recycled materials from around the world. Washington lawmakers, responding to the loss of a market that took upwards of 60 percent of the state’s recycled materials, created the Recycling Development Center in 2019. Lawmakers instructed the state Department of Ecology, via the new center, to help create domestic markets for the state’s recyclable materials.  Washington was on course to lead the way in tackling big recycling problems surrounding plastics and other materials, but the Recycling Development Center got off to a slow start as the COVID-19 pandemic caused agencies to shift to remote work and Governor Jay Inslee froze unnecessary hiring. The center’s 14-member advisory board, made up of scientists, manufacturers, environmentalists and more, started meeting virtually in 2020, later offering grants to pilot recycling projects and funding studies that identified recycling options and issues. Presort Lead Jameel Henricksen, right, and Sorter Jerome Thomas remove plastic bags at Waste Management’s SMaRT Center in Spokane, Wash., on Wednesday, April 10, 2013. Young Kwak / Inlander “We had resources from the Legislature that we couldn’t use to hire a consultant, so we set up a little grant program for local governments and universities,” says Kara Steward, director of the Recycling Development Center.  Recently, the center has been able to support business accelerator competitions, such as NextCycle Washington, which aims to identify innovative ideas that can create a circular economy for materials like plastic. People with promising ideas will get help pitching to investors and connecting with groups that have far deeper pockets than a state program, Steward says.  “We’re really excited because this is not the kind of thing the Department of Ecology does,” Steward says. “We’re about keeping human health and the environment clean, and I’m over here going, ‘But wait, I want to give money to businesses!’ Everybody around me is like, ‘You can’t do that.’ ‘Yeah, actually, I think I can.’” New ideas that focus on solutions outside of the recycling system are also welcomed, as packaging innovations may better reduce the waste we create. “We can’t recycle our way out of the plastic problem,” Steward says. “We’ve recycled 8 percent of the plastic manufactured since the beginning of plastic. We’ve got to think outside the box, do new things, and NextCycle Washington is a great way to try and give a boost to those innovations that just need a little bit of help.”  In a 2021 report funded by the Recycling Development Center, research professor Karl Englund and a civil and environmental engineering team at Washington State University outlined existing chemical and thermal recycling options for plastic — such as heat-intensive solutions like pyrolysis and gasification, or catalyst-based solutions like glycolysis — and assessed their viability to operate in the Pacific Northwest. Chemical recycling can create new plastics, syngas (made from hydrogen and carbon monoxide from wood, plastics or other sources), bio oils, and other products. The report found there could be enough post-consumer plastics in either eastern Washington or the Puget Sound region to support a chemical recycler on either side of the state if consumer recycling rates were to increase significantly — from a current rate of about 8 percent to 50 percent. But the report also notes that the costs to open a new facility can be prohibitive, especially as the market prices for end products can vary. “There is a definite need to secure investment dollars to make any recycling process a success,” the report states. “Having investors that are educated and informed about the recycling supply chain is a must for them to be comfortable to invest in what can be a somewhat risky venture. Without sufficient investment management, smaller companies and start-ups will have a difficult time securing investments and mitigating risks.” The research team also compiled a database of hundreds of existing recyclers. Though it was updated in spring 2022, the list could already be updated with 100 new companies trying to work on plastic recycling, Englund says. Maintaining a reliable list is a challenge, as companies often make a big splash when they announce their promising new recycling process, but some fade away if their process doesn’t pencil out or get funding, Englund says.  Massive multinational companies such as Dow or BASF, which make additives that help in the more popular mechanical recycling processes, are more likely to stick around, as their products are readily available and backed with more finances, Englund explains.  Even when new facilities do open, they don’t always work as intended. One company in recent years offered Boise, Idaho, the ability to recycle its plastic films like bags and peel-back container tops into diesel fuel, but much of what was collected ultimately ended up getting burned for energy rather than converted to fuel, Reuters reported last year. The company said the switch was due to high levels of contamination in Boise’s recycling stream, but Reuters noted that multiple other “advanced recycling” projects around the world had also failed or been significantly delayed in recent years, largely due to high costs.  However, Englund says that while many news outlets may focus on the recycling failures, scientists and businesses are making significant progress to advance chemical recycling. “The guys in the plastics world are busting their butt to make this happen,” Englund says. “Do we all need to do more? Yeah. But at least we’re taking steps in the right direction, and I am cautiously optimistic.” New alternatives need to be assessed to ensure they’re a better option than continuing to churn out new plastic. For example, say that a store switches to glass bottles that can be returned for a deposit, washed, refilled and put back on the shelf. Does the weight of transporting those glass containers in vehicles contribute to worse gas mileage and a larger carbon footprint than lightweight, recyclable plastic containers? How much water is needed to clean the containers versus produce new ones?  For advanced recycling, companies have to calculate whether the energy needed to chemically break down and rebuild plastics is higher than the greenhouse gas emissions of creating new plastics. Upstream, packaging design decisions can also help make products more recyclable. Take a plastic container that holds bleach wipes. If the body of the container is white, the top of the container is another color, and the label is printed directly onto the plastic, those dyes can “contaminate” the process when recyclers are trying to achieve one homogenous color, Englund says. “When we develop that plastic at the very beginning, we’ve got to look and say, ‘How can I get this back to this form at the end of its life?’” Englund says.  A better design for that container of wipes might be as simple as using one color for the entire container and printing the label on paper, which is far easier to remove before the chemical recycling process and also could be separately recycled, he says. Englund also wonders whether other design features such as symbols imprinted with infrared ink could help materials recovery facilities more easily sort the different materials.  There may also need to be changes on the consumer side, he says, as a lot of design is based around consumer preferences for package appearance. “How do we as a society learn to accept things not in a million different colors [with] all these cool things added to it?” Englund asks. “You know, hey, it’s just milk.” Some states are helping tip the scale in favor of circular systems by requiring higher percentages of post-consumer recycled materials in packaging in coming years. Some are also passing “extended producer responsibility” rules that require manufacturers to pay for the recycling of their products at the end of their life cycle. Those policies could make some plastic recycling methods pencil out, as manufacturers will be more inclined to buy the recycled products to meet state mandates. Western Washington University freshman Anna Armstrong, 18, on campus Tuesday morning Sept. 20, 2022, in Bellingham, Wash. Armstrong is planning to major in environmental science and minor in environmental justice. Paul Conrad / InvestigateWest Amazingly, you don’t need to work in a multimillion-dollar lab backed by a massive corporation to design a plastic alternative.  For 18-year-old Anna Armstrong, the desire to help solve the world’s plastic problem started particularly young. Early in her freshman and sophomore science classes at Ferris High School in Spokane, Armstrong studied the potential of fungus to enhance composting. As she saw how difficult it was to compost bioplastics that are already available in the grocery store, she wondered if she could invent an alternative. She researched some of the options being explored, such as using the skin of invasive fish species to make bioplastics, which tackles two environmental problems at once. But working with smelly fish skins wasn’t exactly appealing. Her compost work led her to a specific fungus, Aspergillus oryzae, and she wondered if it could be used to break down the types of plant starch-based plastics, such as compostable trash can liners, that are becoming more popular in the plastic-alternatives field. “Aspergillus oryzae is found in Asia a lot of the time in food management because it is used for fermenting rice,” Armstrong says. “I was looking into what it does, and it kind of links to the starch and starts to eat away at it, which helps the fermentation process. So I cross applied that to plastic degradation to see how I could fix a separate problem.” During the last two years of her high school biomedical innovation classes — much of the time working remotely due to the pandemic — she researched sustainable sources for arrowroot powder, vinegar and vegetable glycerin that could create thin sheets of plastic similar to those found wrapped around products on store shelves, and set to work creating her own prototypes.  “I tried probably 30 or 40 recipes before I actually landed on one that I could use,” Armstrong says. “The ratios can be pretty tricky.” She also tried to adjust her methods to make the prototypes more transparent and with as few visible imperfections as possible, because consumers can be picky.  Armstrong took her bioplastic to the Eastern Washington Regional Science and Engineering Fair, where she took first place for her invention and went on to compete virtually in the International Science and Engineering Fair in Atlanta, Georgia, where she placed fourth in the world in the environmental engineering category this year. Judges there helped her talk through how to reduce water usage when creating the bioplastic film and coached her on how to describe her work. This fall, she’s starting college at Western Washington University, where she plans to major in environmental science and minor in environmental justice. Ultimately, she wants to get her PhD in mycology (the study of fungi, such as mushrooms) as she continues developing her product, which she hopes to see on store shelves one day. “I want to prove that it isn’t impossible to make a plastic that actually works and is environmentally friendly,” Armstrong says. “If I can do it at 17, then scientists who have been working forever in the environmental engineering field should be capable of making it with years of experience.” Part of her passion also stems from growing up with fears of how climate change will impact the planet in her lifetime. She says scientists are trying everything they can to get the world to heed their warnings, but it doesn’t seem like anyone is taking action. “I really want to live in a world [where] I don’t have to worry about what the future generations can look like, and not even future generations of humans, I’m talking about all the flora and fauna that lives in the world and depends on the environment around us,” Armstrong says. “Fear isn’t an excuse to be complacent. Because other people haven’t done it doesn’t mean you can’t.”  InvestigateWest (invw.org) is an independent news nonprofit dedicated to investigative journalism in the Pacific Northwest. Visit invw.org/newsletters to sign up for weekly updates. This story was made possible with support from the Sustainable Path Foundation. This story was originally published by Grist with the headline ‘We can’t recycle our way out’ on Oct 1, 2022.

From chemical recycling to plant-based alternatives, scientists size up the most promising solutions to plastic pollution.

Read the full story here.
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Where did the PFAS in your blood come from? These computer models offer clues

Downstream of a Chemours fluorochemical manufacturing plant on the Cape Fear River in North Carolina, people living in Brunswick and New Hanover counties suffer from higher-than-normal rates of brain tumors, breast cancers and other forms of rare — and accelerated — diseases. Residents now know this isn’t a coincidence. It’s from years of PFAS contamination from Chemours. It wasn’t easy to make the connection. More than a decade of water testing and lawsuits identified the link between aggressive cancers and per-and polyfluoroalkyl substances, or PFAS – a class of more than 9,000 toxic and persistent man-made compounds known informally as “forever chemicals.” They’re commonly found in nonstick cookware, water-resistant clothing, firefighting foam, cosmetics, food packaging and recently in school uniforms and insecticides. The difficulty of tracing these chemicals to a specific source is that Americans — 97% of us, by one estimate — are exposed to potentially thousands of PFAS. New research published in Science of the Total Environment now finds that tracing models can identify sources of PFAS contamination from people’s blood samples. Instead of using environmental measures of PFAS as a proxy for how people are exposed, the methods use blood samples as a more direct way to map people’s exposure. “If this works, it would allow us to identify, without any prior knowledge, what people are being exposed to and how they’re being exposed to it,” Dylan Wallis, a lead author of the paper and toxicologist formerly at North Carolina State University, told EHN. The research, while not yet perfect, marks the beginning of what could become a wide-scale method of determining where the PFAS in our blood came from—such as our food, drinking water or use of nonstick cookware—and how much of it came from each source. But its effectiveness hinges on the need to collect more comprehensive data on where PFAS occurs in people’s bodies, the environment and sources. If scientists can collect this data, then these methods would be able to draw a roadmap for people’s exposure, allowing us to pinpoint problem areas, avoid contamination and implement regulatory changes. PFAS in blood samplesFor this tracing method to work, scientists need an idea of which compounds exist in air, water, food and everyday products in a determined community. First, they have to know where to look for PFAS. This study used data from previous research to identify the types of PFAS in drinking water. Then, they test blood samples for which PFAS are in people’s bodies—although using blood alone gives us only part of the contamination picture, Carla Ng, a chemical and biological engineer at University of Pittsburgh, told EHN. Once they match PFAS proportions in blood to what’s in their drinking water, as in this study, they can gain clues to which sources contributed the chemicals showing up in people’s blood.“You start to build this picture of what are the inputs, what’s the material they’re getting their exposure from, and then what’s in their blood,” Ng, who was not involved in the study, explained. The new study analyzed blood samples taken in 2018 and 2020 from residents in Wilmington, North Carolina, and three towns in El Paso County, Colorado. Both communities are near well-known PFAS polluters: the Chemours facility in North Carolina, which manufactures fluoropolymers for nonstick and waterproof products, and the Peterson Space Force Base in Colorado, which uses PFAS-containing firefighting foam, also called AFFFs. Related: PFAS on our shelves and in our bodiesThe team used computer models to identify 20 PFAS compounds from residents’ blood samples and then grouped them in categories representing different sources. Some are easy to identify because manufacturers often use a specific type of PFAS. For example, the compounds found in firefighting foam have a unique signature, like a fingerprint, making Peterson Space Force Base the obvious culprit. But more diffuse sources of PFAS, such as those in dust or food, are harder to pin down because scientists aren’t sure which PFAS are in them or where they come from.In North Carolina and Colorado, the sources were more obvious, allowing the research team to test models’ ability to identify sources. However, to conduct similar research on a national scale is not so simple. The U.S. Centers for Disease Control and Prevention’s National Health and Nutrition Examination Survey has tested levels of PFAS in blood samples nationwide since 1999, but it only tests for a specific list of PFAS, which could overlook the full spectrum of compounds. Drinking water in both locations in the study shows high levels of fluoroethers and fluoropolymers, many of which are “legacy” PFAS, meaning they have been phased out of production for at least a decade but are still found in drinking water. Because the chemical bonds are so strong, they persist in the environment for years, which is why they show up in blood samples long after companies have stopped using or manufacturing them. Long-chain PFAS like PFOA and PFOS, which are the most-studied compounds with a longer structure of carbon-fluorine bonds, are harder to break down, and they bond to proteins in the blood more easily than short-chain compounds.“These last a really long time,” Wallis said of long-chain PFAS, which were recorded at levels several times higher than national averages. “If you were drinking a really high level of it 40 years ago, you would still have really high levels of it 40 years later.”A pollution snapshotWallis said they were surprised the models worked because they have never been used for PFAS before. They were built to trace other contaminants in the environment, like particles in air pollution, rather than in people.Tracing PFAS is more challenging than tracing air pollution for several reasons, Xindi Hu, a lead data scientist at the research organization Mathematica, told EHN. Hu conducted earlier research using a different type of computer analysis of blood samples to identify the main sources of PFAS contamination in the Faroe Islands. Many PFAS lack distinct chemical fingerprints to tell researchers exactly where a particular compound came from, Hu said. But in the study led by Wallis, the chemical fingerprints from the Space Force base in Colorado and fluorochemical facility in North Carolina are well-known.“When you take a blood sample, it’s really just a snapshot,” she said. “So how do you translate this snapshot of concentration back to the course of the entire exposure history?”That’s partly why the new paper’s authors conducted this study: The more compounds that are correctly linked to a source, the better these models will work, Wallis said. In essence, they need a better database of PFAS compounds so the models know how to connect the dots. PFAS also react differently in the human body than in the environment, and scientists still don’t fully understand how we metabolize different compounds. Shorter-chain PFAS, for example, are more likely to appear in urine samples than in blood because they are water-soluble, said Pittsburgh’s Ng, who studies how PFAS react in humans and wildlife. “If you’re doing everything on the basis of blood levels, it may not tell you everything you need to know about exposure and potential toxicity,” she said, adding that PFAS could also accumulate in the liver, brain, lungs and other locations where it’s difficult to take samples. Worse, more modern PFAS with carbon-hydrogen bonds can actually transform into other types of compounds as the body metabolizes them, which could give a false impression of what people are exposed to. “The key to identifying a good tracer is a molecule that doesn’t transform,” Ng said. Some PFAS are great tracers, she added, but “the more transformable your PFAS is in general, the poorer the tracer is going to be.”That’s why newer PFAS compounds like GenX were not detected in blood samples or used as tracers in the recent study. “These models aren’t going to account for everything,” Wallis said. “No model is.” Stopping the contamination Wallis and their co-authors said they hope the models can become more accurate for less exposed communities in the future. With more data, it would be easier to suggest what to avoid instead of guessing where PFAS exposures come from, Wallis said, adding that it could lead to more protective regulations.Although these models can vaguely help identify where compounds might come from in a particular community, it’s not a definitive solution, Alissa Cordner, an environmental sociologist and co-director of the PFAS Project Lab who was not involved in the recent study, told EHN. Even if there’s no immediate application of these methods, identifying where PFAS are is the first step.“Everybody can point their fingers at other possible sources of contamination,” Cordner said. “The best way to address this is not to try to, after the fact, link people’s exposure to a contamination source. It’s to stop the contamination.”

Downstream of a Chemours fluorochemical manufacturing plant on the Cape Fear River in North Carolina, people living in Brunswick and New Hanover counties suffer from higher-than-normal rates of brain tumors, breast cancers and other forms of rare — and accelerated — diseases. Residents now know this isn’t a coincidence. It’s from years of PFAS contamination from Chemours. It wasn’t easy to make the connection. More than a decade of water testing and lawsuits identified the link between aggressive cancers and per-and polyfluoroalkyl substances, or PFAS – a class of more than 9,000 toxic and persistent man-made compounds known informally as “forever chemicals.” They’re commonly found in nonstick cookware, water-resistant clothing, firefighting foam, cosmetics, food packaging and recently in school uniforms and insecticides. The difficulty of tracing these chemicals to a specific source is that Americans — 97% of us, by one estimate — are exposed to potentially thousands of PFAS. New research published in Science of the Total Environment now finds that tracing models can identify sources of PFAS contamination from people’s blood samples. Instead of using environmental measures of PFAS as a proxy for how people are exposed, the methods use blood samples as a more direct way to map people’s exposure. “If this works, it would allow us to identify, without any prior knowledge, what people are being exposed to and how they’re being exposed to it,” Dylan Wallis, a lead author of the paper and toxicologist formerly at North Carolina State University, told EHN. The research, while not yet perfect, marks the beginning of what could become a wide-scale method of determining where the PFAS in our blood came from—such as our food, drinking water or use of nonstick cookware—and how much of it came from each source. But its effectiveness hinges on the need to collect more comprehensive data on where PFAS occurs in people’s bodies, the environment and sources. If scientists can collect this data, then these methods would be able to draw a roadmap for people’s exposure, allowing us to pinpoint problem areas, avoid contamination and implement regulatory changes. PFAS in blood samplesFor this tracing method to work, scientists need an idea of which compounds exist in air, water, food and everyday products in a determined community. First, they have to know where to look for PFAS. This study used data from previous research to identify the types of PFAS in drinking water. Then, they test blood samples for which PFAS are in people’s bodies—although using blood alone gives us only part of the contamination picture, Carla Ng, a chemical and biological engineer at University of Pittsburgh, told EHN. Once they match PFAS proportions in blood to what’s in their drinking water, as in this study, they can gain clues to which sources contributed the chemicals showing up in people’s blood.“You start to build this picture of what are the inputs, what’s the material they’re getting their exposure from, and then what’s in their blood,” Ng, who was not involved in the study, explained. The new study analyzed blood samples taken in 2018 and 2020 from residents in Wilmington, North Carolina, and three towns in El Paso County, Colorado. Both communities are near well-known PFAS polluters: the Chemours facility in North Carolina, which manufactures fluoropolymers for nonstick and waterproof products, and the Peterson Space Force Base in Colorado, which uses PFAS-containing firefighting foam, also called AFFFs. Related: PFAS on our shelves and in our bodiesThe team used computer models to identify 20 PFAS compounds from residents’ blood samples and then grouped them in categories representing different sources. Some are easy to identify because manufacturers often use a specific type of PFAS. For example, the compounds found in firefighting foam have a unique signature, like a fingerprint, making Peterson Space Force Base the obvious culprit. But more diffuse sources of PFAS, such as those in dust or food, are harder to pin down because scientists aren’t sure which PFAS are in them or where they come from.In North Carolina and Colorado, the sources were more obvious, allowing the research team to test models’ ability to identify sources. However, to conduct similar research on a national scale is not so simple. The U.S. Centers for Disease Control and Prevention’s National Health and Nutrition Examination Survey has tested levels of PFAS in blood samples nationwide since 1999, but it only tests for a specific list of PFAS, which could overlook the full spectrum of compounds. Drinking water in both locations in the study shows high levels of fluoroethers and fluoropolymers, many of which are “legacy” PFAS, meaning they have been phased out of production for at least a decade but are still found in drinking water. Because the chemical bonds are so strong, they persist in the environment for years, which is why they show up in blood samples long after companies have stopped using or manufacturing them. Long-chain PFAS like PFOA and PFOS, which are the most-studied compounds with a longer structure of carbon-fluorine bonds, are harder to break down, and they bond to proteins in the blood more easily than short-chain compounds.“These last a really long time,” Wallis said of long-chain PFAS, which were recorded at levels several times higher than national averages. “If you were drinking a really high level of it 40 years ago, you would still have really high levels of it 40 years later.”A pollution snapshotWallis said they were surprised the models worked because they have never been used for PFAS before. They were built to trace other contaminants in the environment, like particles in air pollution, rather than in people.Tracing PFAS is more challenging than tracing air pollution for several reasons, Xindi Hu, a lead data scientist at the research organization Mathematica, told EHN. Hu conducted earlier research using a different type of computer analysis of blood samples to identify the main sources of PFAS contamination in the Faroe Islands. Many PFAS lack distinct chemical fingerprints to tell researchers exactly where a particular compound came from, Hu said. But in the study led by Wallis, the chemical fingerprints from the Space Force base in Colorado and fluorochemical facility in North Carolina are well-known.“When you take a blood sample, it’s really just a snapshot,” she said. “So how do you translate this snapshot of concentration back to the course of the entire exposure history?”That’s partly why the new paper’s authors conducted this study: The more compounds that are correctly linked to a source, the better these models will work, Wallis said. In essence, they need a better database of PFAS compounds so the models know how to connect the dots. PFAS also react differently in the human body than in the environment, and scientists still don’t fully understand how we metabolize different compounds. Shorter-chain PFAS, for example, are more likely to appear in urine samples than in blood because they are water-soluble, said Pittsburgh’s Ng, who studies how PFAS react in humans and wildlife. “If you’re doing everything on the basis of blood levels, it may not tell you everything you need to know about exposure and potential toxicity,” she said, adding that PFAS could also accumulate in the liver, brain, lungs and other locations where it’s difficult to take samples. Worse, more modern PFAS with carbon-hydrogen bonds can actually transform into other types of compounds as the body metabolizes them, which could give a false impression of what people are exposed to. “The key to identifying a good tracer is a molecule that doesn’t transform,” Ng said. Some PFAS are great tracers, she added, but “the more transformable your PFAS is in general, the poorer the tracer is going to be.”That’s why newer PFAS compounds like GenX were not detected in blood samples or used as tracers in the recent study. “These models aren’t going to account for everything,” Wallis said. “No model is.” Stopping the contamination Wallis and their co-authors said they hope the models can become more accurate for less exposed communities in the future. With more data, it would be easier to suggest what to avoid instead of guessing where PFAS exposures come from, Wallis said, adding that it could lead to more protective regulations.Although these models can vaguely help identify where compounds might come from in a particular community, it’s not a definitive solution, Alissa Cordner, an environmental sociologist and co-director of the PFAS Project Lab who was not involved in the recent study, told EHN. Even if there’s no immediate application of these methods, identifying where PFAS are is the first step.“Everybody can point their fingers at other possible sources of contamination,” Cordner said. “The best way to address this is not to try to, after the fact, link people’s exposure to a contamination source. It’s to stop the contamination.”

In search of the principles of life

Associate Professor Otto Cordero is looking for the fundamental constraints that shape microbial ecosystems.

MIT Associate Professor Otto Cordero has always gravitated toward the most basic questions of life. How do ecosystems assemble? Why do species divide labor in nature? He believes these are some of the most central questions for understanding life. “The challenge is discovering something that applies across organisms and across environments — now we’re talking about a fundamental constraint of life,” says Cordero, who recently earned tenure in the MIT Department of Civil and Environmental Engineering. “I really care about that type of thing. That’s where it ends for me. Why are things the way they are? Why do they look the way they do and function the way they do? It’s because there are constraints. It’s evolution. It’s how the world works. Discovering those principals is the ultimate prize.” Cordero’s search has led him into areas of research he never could have imagined. Along the way, he’s made progress toward understanding microbial ecosystems through the broad factors that dictate their composition and behavior. “I talk to a lot of physicists, and they all tell the same story,” Cordero says, smiling. “Many years ago, there were people looking at the molecules of a gas, trying to predict where each one will be, and then somebody at some point figured out there were master variables: pressure, volume, and temperature, and they all relate to each other very nicely. Now they have the gas law, and everything makes sense once you understand those variables. It’s unclear if master variables like that exist in biology, and even more so in microbial ecology, but it’s certainly worth looking for them.” Embracing chance Cordero was raised by his mother in Guayaquil, Ecuador, where he says scientific activity was sparse. “I never met a scientist in my life,” Cordero says. “At my university in Ecuador, there was one teacher who had a PhD, and everybody called him doctor.” Although no one in Cordero’s family had gone to college, his mother prioritized his education, and Cordero gained an appreciation for reading and learning from his grandfather. Those influences led him to a technical college for his undergraduate degree. Cordero’s childhood was humble — there were days he had to borrow 25 cents just to catch a bus to campus. But a pivotal moment came when he received a scholarship to attend Utrecht University for graduate school in the Netherlands. “Everything is serendipitous,” Cordero says. “I tell my students when I look back, I could never have predicted where I’d be in three to five years.” Up to that point, Cordero hadn’t met many people outside of Ecuador, but he jokes that he met someone from every country in Europe within a week. He’d go on to make friends from around the world. While majoring in artificial intelligence as a master’s student, Cordero became interested in algorithms that described the organization of organisms like insects. One day he was searching through papers on the subject when a Dutch name caught his eye. It turned out to be a professor in the building next to him. He hurried over and met the professor, Paulien Hogeweg, who was studying fundamental questions of life using computational biology. Cordero fell in love with the subject, and Hogeweg would become his PhD advisor. Serendipity struck again when Cordero began his postdoctoral work at MIT, where he worked under longtime MIT professor Martin Polz, who is now a professor at the University of Vienna. “I ended up opening this area of research for myself that I never imagined before,” Cordero says. “I started to study microbial interactions — essentially how different strains or species of bacteria interact in the environment.” Through that work, Cordero uncovered mechanisms microbes use to work together or kill off competing species, which have major implications for microbial ecosystems and perhaps also large biogeochemical processes like the carbon cycle. “From there, I was an expert in microbial interactions and evolution,” Cordero says. “I was working on exciting projects, and when that happens at MIT the environment lifts you up. Everybody wants to talk to you about the next idea. It’s stimulating. I enjoy that very much. The dynamics and exposure here are unrivaled. I feel like I go to a talk and I know what the next big-impact paper is going to be.” Cordero joined the faculty at MIT in 2015, and he’s continued studying microbes to explore how biological systems function and evolve. In keeping with that mission, in 2017 Cordero helped assemble an interdisciplinary group of researchers from around the world to look for universal principles of biology that could help explain and predict the behavior of microbial systems. The resulting collaboration, called Principles of Microbial Ecosystems (PRIME), has made progress identifying environmental factors and constraints that help shape all ecosystems. For instance, PRIME researchers have profiled the metabolic processes of hundreds of species of microbes to place them into broader metabolic classes that can be used to accurately model and predict the behavior of ecosystems. “Trying to make sense of the diversity of microorganisms, or any organism, in an environment is really complex, so the natural instinct is to start with little things — to see what one organism does,” Cordero says. “I wanted to look for things that could be generalized. Is there some sort of principal that helps explain or predict why communities assemble this way, or what we should expect in this environment or that environment? We see these broad patterns, and it begs the question of what the right variables are to study. Things become much simpler and more predictable when you identify those right variables.” Focusing on the bigger picture Cordero says he wants to break stereotypes about academics, like that they all come from elite schools and affluent families. He also wants to show students that researchers can have fun while working hard. Before the pandemic, Cordero played in a band with students from his department that featured two PhD students on guitar, a postdoctoral drummer, an MBA on the trumpet, and a master’s student singing. “That was the highlight of the week for me,” Cordero says. “Hopefully we bring it back!” Cordero’s personal life has also gotten a bit busier since the start of the pandemic — he now has a 2-year-old and 5-month-old. Overall, whether in his personal life or work, Cordero tries to focus on the big picture. “When you sequence [the genome] of something, you get this long list of taxa with Latin names, but that’s not really the most important information,” Cordero says. “The vision is that one day — hopefully not too far into the future — we can transform that information into more functional variables. [This goes back to] the pressure-volume-temperature analogy. Maybe these ecosystems can be understood with simple models, and maybe we can predict what they will do in the future. That would be a huge game-changer.”

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