Chemical recycling grows — along with concerns about its environmental impacts

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Wednesday, September 28, 2022

St. James Parish, located on a stretch of the Mississippi River between Baton Rouge and New Orleans dubbed “Cancer Alley” due to the high concentration of petrochemical plants, is home to the country’s largest producer of polystyrene — the foam commonly found in soft drink and takeout containers. Now, the owner of that plant wants to build a new facility in the same area that would break down used foam cups and containers into raw materials that can be turned into other kinds of plastic. While there’s limited data on what kinds of emissions this type of facility creates, environmental advocates are concerned that the new plant could represent a new source of carcinogens like dioxin and benzene in the already polluted area.The proposed plant comes as the U.S. federal and state governments and private companies pour billions into “chemical recycling” research, which is touted as a potential solution to anemic plastics recycling rates. Proponents say that, despite mounting restrictions on single-use packaging, plastics aren’t going away anytime soon, and that chemical recycling is needed to keep growing amounts of plastic waste out of landfills and oceans. But questions abound about whether the plants are economically viable — and how chemical recycling contributes to local air pollution, perpetuating a history of environmental injustices and climate change. Skeptics argue that chemical recycling is an unproven technology that amounts to little more than the latest PR effort from the plastics industry. The Environmental Protection Agency is deciding whether or not to continue regulating the plants as incinerators, with some lawmakers expressing concerns last month about toxic emissions from these facilities. “They’re going to be managing toxic chemicals…and they’re going to be putting our communities at risk for either air pollution or something worse,” Jane Patton, a Baton Rouge native and manager of the Center for International Environmental Law’s plastics and petrochemicals campaign, told EHN of the proposed new plant in Louisiana.The air of St. James Parish, where the new plant will be located, has among the highest pollution levels along the Mississippi River corridor dubbed “Cancer Alley.” A joint investigation in 2019 by ProPublica, The Times-Picayune and The Advocate found that most of the new petrochemical facilities in the parish –including the recycling plant– will be located near the mostly Black 5th District.What is chemical recycling?When most of us picture recycling, we picture what industry insiders call “mechanical recycling:” plastics are sorted, cleaned, crushed or shredded and then melted to be made into new goods. In the U.S., though, less than 10% of plastics are actually recycled due to challenges ranging from contamination to variability in plastic types and coloring. “No flexible plastic packaging can be recycled with mechanical recycling — the only real plastic that can be recycled are number one and number two water bottles and milk jugs,” George Huber, an engineering professor at the University of Wisconsin and head of the multi-university research center for Chemical Upcycling of Waste Plastics, told EHN. Enter chemical recycling –– processes that use high heat, chemicals, or both to break used plastic goods down into their chemical building blocks to, in theory, make more plastics. Proponents say that chemical recycling can complement more traditional recycling by handling mixed and harder-to-recycle plastics. “An advantage of advanced recycling is that it can take more of the 90% of plastics that aren’t recycled today, including the hard-to-recycle films, pouches and other mixed plastics, and remake them into virgin-quality new plastics approved for medical and food contact applications,” Joshua Baca, vice president of the plastics division at the American Chemistry Council, told EHN. A long and winding historyThe technology has actually been around for decades, with an initial wave of plants built in the 1990s, but it didn’t take off then because of operational and economic challenges. Huber said some factors have changed, like a significant increase in plastic use and China’s refusal to accept other countries’ waste, that make chemical recycling more viable this time around. Yet a 2021 Reuters investigation found that commercial viability remains a major challenge for chemical recyclers due to difficulties like contamination of the incoming plastic, high energy costs, and the need to further clean the outputs before they can become plastic. “It's one thing in theory to design something on paper — it's a whole huge challenge to build a plant, get it operational, get the permits and for it to perform like you think it would,” Huber said. Tracking down just how many chemical recycling plants operate today in the U.S. is tricky — and depends in part on what one counts as “recycling.” Potential climate impacts Most of the plants in the U.S. are pyrolysis facilities, which use huge amounts of energy to heat plastics up enough to break their chemical bonds, raising concerns about their climate impacts if that energy comes from burning fossil fuels. An analysis from Closed Loop Partners found that, depending on the technology, carbon emissions from chemical recycling ranged from 22% higher to 45% lower than virgin plastics production. “It's a very promising technology to tackle the problem of (plastic) waste, but if you don't concurrently tackle the challenge of where the energy is coming from, there's a problem,” Rebecca Furlong, a chemistry PhD candidate at the University of Bath who has conducted life cycle assessments of plastics recycling technologies, told EHN. A life cycle assessment study prepared for a British chemical recycling company found that chemical recycling has a significantly lower climate impact than waste-to-energy incineration — but produced almost four times as many greenhouse gas emissions as landfilling the plastic. The American Chemistry Council, or ACC, says that there are at least seven plants in the U.S. doing plastics-to-plastics recycling, although many of those facilities also turn plastics into industrial fuel. For example, according to records reviewed by the Global Alliance for Incinerator Alternatives, or GAIA, in 2018 a facility located in Oregon and owned by one of the companies planning to build the Louisiana plant, converted 216.82 pounds of polystyrene into the plastics building block styrene, sending roughly the same amount to be burned at a cement kiln. The ACC, European Union regulators and Furlong and her advisor, Matthew Davidson, say plastics to fuel shouldn’t count as recycling. “Clearly digging oil out of the ground, using it as a plastic, and then burning it is not hugely different from digging it out of the ground and burning it,” Davidson, director of the Centre for Sustainable and Circular Technologies at the University of Bath, told EHN.Unknowns about environmental health impacts Chemical recycling saw a boost under the Trump administration, including a formal partnership between the federal Department of Energy and the American Chemistry Council, which lobbies on behalf of the plastics industry, to scale up chemical recycling technologies. There’s limited information, however, on the environmental health impacts of chemical recycling plants. Furlong said she had not included hazardous waste generation in her life cycle assessments because of a lack of data. Tangri said there have been few studies outside the lab, in part because there are relatively few chemical recycling plants out there. Additionally, the ones that do exist are either too small to meet the EPA’s pollution reporting threshold, or are housed within a larger petrochemical complex and so don’t separately report out their air pollution emissions. Earlier this year, the Natural Resources Defense Council released a report looking at eight facilities in the U.S. The environmental group found that one facility in Oregon sent around half a million pounds of hazardous waste, including benzene and lead, to incinerators in Washington, Colorado, Missouri and three other states. Hazardous waste incinerators can release toxic air pollution to nearby communities. Additionally, some hazardous waste incinerators in the U.S. have repeatedly violated air pollution standards and the EPA has recently raised serious concerns about a backlog of hazardous waste piling up due to limited incineration capacity. The Oregon facility, which is supposed to break down polystyrene into styrene, also sent more than 100,000 pounds of styrene in 2020 to be burned in waste to energy plants rather than recycled back into new plastics, according to the Natural Resources Defense Council’s report. Plastics contain a range of additives, like phthalates and bisphenols, that have serious health concerns. The European Chemicals Agency expressed concerns in a 2021 report about the extent to which chemical recycling could eliminate these chemicals, especially “legacy” additives like lead-stabilized PVC that the EU no longer allows, and prevent them from showing up in new plastic products. The agency also cautioned that, depending on the type of plastic waste the facilities are processing, pyrolysis and gasification plants can generate hazardous compounds such as dioxins, volatile organic compounds and PCBs. Dioxins are considered “highly toxic” by the EPA as they can cause cancer, reproductive issues, immune system damage and other health issues. Volatile organic compounds can cause breathing difficulties and harm the nervous system; and some, like benzene, are also carcinogens. The agency noted that companies are required to take measures, like installing flue gas cleaning systems and pre-treatment of wastewater, to limit emissions. Additionally, experts interviewed by the EU highlighted an overall lack of transparency about the kinds of chemicals used in some of the chemical recycling processes. The American Chemistry Council, or ACC, says that emissions from most chemical recycling plants are too low to trigger Clean Air Act permits, citing a recent report from consultant Good Company and sponsored by the ACC that found that emissions from four plants in the U.S. were on par with those from a hospital and food manufacturing plant. The trade group claims the plants are “designed to avoid dioxin formation with many interventions, the primary one being that the plastic material is heated in a closed, oxygen-deprived environment that is not combustion,” and that the facilities would be subject to violations or operating restrictions if dioxins were formed. Policy debateAs the EPA decides what to do about chemical recycling plants, 20 states — including Louisiana, where the new plant could be built — have already passed laws that would regulate the facilities as manufacturers rather than solid waste facilities, according to the American Chemistry Council — a move that environmental advocates say could lead to less oversight and more pollution. “Whenever I see a big push for exemptions from environmental statutes, I get a little concerned,” Judith Enck, director of the anti-plastics advocacy group Beyond Plastics, told EHN. Advocates in Louisiana fear the new law will exempt the new facility from being regulated by the state Department of Environmental Quality, something the ACC says won’t happen. However, it is unclear in the text of the law which state agency will oversee its environmental impacts (the state Department of Environmental Quality didn’t respond to our question). In a recent letter to the EPA, U.S. Sen. Cory Booker, D-N.J., and more than 30 other lawmakers requested that the agency continue to regulate pyrolysis and gasification plants as incinerators. Additionally, they also urged the EPA to request more information from these facilities on their air pollution and climate impacts. “Communities located near these facilities need to know what chemicals they are being exposed to, and they need the full protection that Congress intended the Clean Air Act’s incinerator standards to provide,” wrote the lawmakers. The American Chemistry Council contends that chemical recycling plants take in plastics waste that is already sorted, and that regulating these facilities as solid waste facilities, with measures like odor and rodent controls, does not make sense. The ACC adds that, like other manufacturing facilities, chemical recycling plants would still be subject to air and water pollution and hazardous waste regulations. Tangri, from GAIA, said that the U.S. should also follow in the footsteps of the EU and not count plastics to fuel as chemical recycling. Overall, environmental advocates would prefer to see stronger measures taken to reduce plastic use and require that manufacturers take more responsibility for plastic packaging — a concept known as “extended producer responsibility.” Enck suggested that there be mandatory environmental standards for packaging similar to auto efficiency standards. “We really need to move to a refillable, reusable economy,” she said. “Do we need all these layers of packaging on a product? Do we need multi-material packaging?”

St. James Parish, located on a stretch of the Mississippi River between Baton Rouge and New Orleans dubbed “Cancer Alley” due to the high concentration of petrochemical plants, is home to the country’s largest producer of polystyrene — the foam commonly found in soft drink and takeout containers. Now, the owner of that plant wants to build a new facility in the same area that would break down used foam cups and containers into raw materials that can be turned into other kinds of plastic. While there’s limited data on what kinds of emissions this type of facility creates, environmental advocates are concerned that the new plant could represent a new source of carcinogens like dioxin and benzene in the already polluted area.The proposed plant comes as the U.S. federal and state governments and private companies pour billions into “chemical recycling” research, which is touted as a potential solution to anemic plastics recycling rates. Proponents say that, despite mounting restrictions on single-use packaging, plastics aren’t going away anytime soon, and that chemical recycling is needed to keep growing amounts of plastic waste out of landfills and oceans. But questions abound about whether the plants are economically viable — and how chemical recycling contributes to local air pollution, perpetuating a history of environmental injustices and climate change. Skeptics argue that chemical recycling is an unproven technology that amounts to little more than the latest PR effort from the plastics industry. The Environmental Protection Agency is deciding whether or not to continue regulating the plants as incinerators, with some lawmakers expressing concerns last month about toxic emissions from these facilities. “They’re going to be managing toxic chemicals…and they’re going to be putting our communities at risk for either air pollution or something worse,” Jane Patton, a Baton Rouge native and manager of the Center for International Environmental Law’s plastics and petrochemicals campaign, told EHN of the proposed new plant in Louisiana.The air of St. James Parish, where the new plant will be located, has among the highest pollution levels along the Mississippi River corridor dubbed “Cancer Alley.” A joint investigation in 2019 by ProPublica, The Times-Picayune and The Advocate found that most of the new petrochemical facilities in the parish –including the recycling plant– will be located near the mostly Black 5th District.What is chemical recycling?When most of us picture recycling, we picture what industry insiders call “mechanical recycling:” plastics are sorted, cleaned, crushed or shredded and then melted to be made into new goods. In the U.S., though, less than 10% of plastics are actually recycled due to challenges ranging from contamination to variability in plastic types and coloring. “No flexible plastic packaging can be recycled with mechanical recycling — the only real plastic that can be recycled are number one and number two water bottles and milk jugs,” George Huber, an engineering professor at the University of Wisconsin and head of the multi-university research center for Chemical Upcycling of Waste Plastics, told EHN. Enter chemical recycling –– processes that use high heat, chemicals, or both to break used plastic goods down into their chemical building blocks to, in theory, make more plastics. Proponents say that chemical recycling can complement more traditional recycling by handling mixed and harder-to-recycle plastics. “An advantage of advanced recycling is that it can take more of the 90% of plastics that aren’t recycled today, including the hard-to-recycle films, pouches and other mixed plastics, and remake them into virgin-quality new plastics approved for medical and food contact applications,” Joshua Baca, vice president of the plastics division at the American Chemistry Council, told EHN. A long and winding historyThe technology has actually been around for decades, with an initial wave of plants built in the 1990s, but it didn’t take off then because of operational and economic challenges. Huber said some factors have changed, like a significant increase in plastic use and China’s refusal to accept other countries’ waste, that make chemical recycling more viable this time around. Yet a 2021 Reuters investigation found that commercial viability remains a major challenge for chemical recyclers due to difficulties like contamination of the incoming plastic, high energy costs, and the need to further clean the outputs before they can become plastic. “It's one thing in theory to design something on paper — it's a whole huge challenge to build a plant, get it operational, get the permits and for it to perform like you think it would,” Huber said. Tracking down just how many chemical recycling plants operate today in the U.S. is tricky — and depends in part on what one counts as “recycling.” Potential climate impacts Most of the plants in the U.S. are pyrolysis facilities, which use huge amounts of energy to heat plastics up enough to break their chemical bonds, raising concerns about their climate impacts if that energy comes from burning fossil fuels. An analysis from Closed Loop Partners found that, depending on the technology, carbon emissions from chemical recycling ranged from 22% higher to 45% lower than virgin plastics production. “It's a very promising technology to tackle the problem of (plastic) waste, but if you don't concurrently tackle the challenge of where the energy is coming from, there's a problem,” Rebecca Furlong, a chemistry PhD candidate at the University of Bath who has conducted life cycle assessments of plastics recycling technologies, told EHN. A life cycle assessment study prepared for a British chemical recycling company found that chemical recycling has a significantly lower climate impact than waste-to-energy incineration — but produced almost four times as many greenhouse gas emissions as landfilling the plastic. The American Chemistry Council, or ACC, says that there are at least seven plants in the U.S. doing plastics-to-plastics recycling, although many of those facilities also turn plastics into industrial fuel. For example, according to records reviewed by the Global Alliance for Incinerator Alternatives, or GAIA, in 2018 a facility located in Oregon and owned by one of the companies planning to build the Louisiana plant, converted 216.82 pounds of polystyrene into the plastics building block styrene, sending roughly the same amount to be burned at a cement kiln. The ACC, European Union regulators and Furlong and her advisor, Matthew Davidson, say plastics to fuel shouldn’t count as recycling. “Clearly digging oil out of the ground, using it as a plastic, and then burning it is not hugely different from digging it out of the ground and burning it,” Davidson, director of the Centre for Sustainable and Circular Technologies at the University of Bath, told EHN.Unknowns about environmental health impacts Chemical recycling saw a boost under the Trump administration, including a formal partnership between the federal Department of Energy and the American Chemistry Council, which lobbies on behalf of the plastics industry, to scale up chemical recycling technologies. There’s limited information, however, on the environmental health impacts of chemical recycling plants. Furlong said she had not included hazardous waste generation in her life cycle assessments because of a lack of data. Tangri said there have been few studies outside the lab, in part because there are relatively few chemical recycling plants out there. Additionally, the ones that do exist are either too small to meet the EPA’s pollution reporting threshold, or are housed within a larger petrochemical complex and so don’t separately report out their air pollution emissions. Earlier this year, the Natural Resources Defense Council released a report looking at eight facilities in the U.S. The environmental group found that one facility in Oregon sent around half a million pounds of hazardous waste, including benzene and lead, to incinerators in Washington, Colorado, Missouri and three other states. Hazardous waste incinerators can release toxic air pollution to nearby communities. Additionally, some hazardous waste incinerators in the U.S. have repeatedly violated air pollution standards and the EPA has recently raised serious concerns about a backlog of hazardous waste piling up due to limited incineration capacity. The Oregon facility, which is supposed to break down polystyrene into styrene, also sent more than 100,000 pounds of styrene in 2020 to be burned in waste to energy plants rather than recycled back into new plastics, according to the Natural Resources Defense Council’s report. Plastics contain a range of additives, like phthalates and bisphenols, that have serious health concerns. The European Chemicals Agency expressed concerns in a 2021 report about the extent to which chemical recycling could eliminate these chemicals, especially “legacy” additives like lead-stabilized PVC that the EU no longer allows, and prevent them from showing up in new plastic products. The agency also cautioned that, depending on the type of plastic waste the facilities are processing, pyrolysis and gasification plants can generate hazardous compounds such as dioxins, volatile organic compounds and PCBs. Dioxins are considered “highly toxic” by the EPA as they can cause cancer, reproductive issues, immune system damage and other health issues. Volatile organic compounds can cause breathing difficulties and harm the nervous system; and some, like benzene, are also carcinogens. The agency noted that companies are required to take measures, like installing flue gas cleaning systems and pre-treatment of wastewater, to limit emissions. Additionally, experts interviewed by the EU highlighted an overall lack of transparency about the kinds of chemicals used in some of the chemical recycling processes. The American Chemistry Council, or ACC, says that emissions from most chemical recycling plants are too low to trigger Clean Air Act permits, citing a recent report from consultant Good Company and sponsored by the ACC that found that emissions from four plants in the U.S. were on par with those from a hospital and food manufacturing plant. The trade group claims the plants are “designed to avoid dioxin formation with many interventions, the primary one being that the plastic material is heated in a closed, oxygen-deprived environment that is not combustion,” and that the facilities would be subject to violations or operating restrictions if dioxins were formed. Policy debateAs the EPA decides what to do about chemical recycling plants, 20 states — including Louisiana, where the new plant could be built — have already passed laws that would regulate the facilities as manufacturers rather than solid waste facilities, according to the American Chemistry Council — a move that environmental advocates say could lead to less oversight and more pollution. “Whenever I see a big push for exemptions from environmental statutes, I get a little concerned,” Judith Enck, director of the anti-plastics advocacy group Beyond Plastics, told EHN. Advocates in Louisiana fear the new law will exempt the new facility from being regulated by the state Department of Environmental Quality, something the ACC says won’t happen. However, it is unclear in the text of the law which state agency will oversee its environmental impacts (the state Department of Environmental Quality didn’t respond to our question). In a recent letter to the EPA, U.S. Sen. Cory Booker, D-N.J., and more than 30 other lawmakers requested that the agency continue to regulate pyrolysis and gasification plants as incinerators. Additionally, they also urged the EPA to request more information from these facilities on their air pollution and climate impacts. “Communities located near these facilities need to know what chemicals they are being exposed to, and they need the full protection that Congress intended the Clean Air Act’s incinerator standards to provide,” wrote the lawmakers. The American Chemistry Council contends that chemical recycling plants take in plastics waste that is already sorted, and that regulating these facilities as solid waste facilities, with measures like odor and rodent controls, does not make sense. The ACC adds that, like other manufacturing facilities, chemical recycling plants would still be subject to air and water pollution and hazardous waste regulations. Tangri, from GAIA, said that the U.S. should also follow in the footsteps of the EU and not count plastics to fuel as chemical recycling. Overall, environmental advocates would prefer to see stronger measures taken to reduce plastic use and require that manufacturers take more responsibility for plastic packaging — a concept known as “extended producer responsibility.” Enck suggested that there be mandatory environmental standards for packaging similar to auto efficiency standards. “We really need to move to a refillable, reusable economy,” she said. “Do we need all these layers of packaging on a product? Do we need multi-material packaging?”

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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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