This month, Eos is taking a long look at “forever chemicals.” Per- and polyfluoroalkyl substances (PFAS) have been percolating through our industrial environment since the 1940s. They help make products nonstick, waterproof, and stain resistant. They also make their way into air, soil, and water, as well as our bodies, where they have been linked to impaired immune systems, developmental delays in children, and some cancers.
Since discovering that PFAS might be harmful to human and environmental health, researchers and industries have reformed the chemicals into novel substances. The behaviors of these novel PFAS are proving difficult to pin down, as Grace van Deelen explores in her feature “Chemical Companies Are Churning Out New PFAS. Where in the World Are They Ending Up?”
From the deep ocean to alpine glaciers, scientists are being forced to play “chemical Whac-A-Mole” to study novel PFAS, one scientist told van Deelen. Researchers are also searching for—and finding—PFAS in the isolated interior of the White Continent, as described in Rebecca Owen’s “Tracing the Path of PFAS Across Antarctica.”
Another option is to put PFAS to work. Read about how scientists are using trifluoroacetic acid, a less toxic PFAS, to gain a rough idea of how recently an aquifer has been recharged in Saima May Sidik’s “Pollution Is Rampant. We Might As Well Make Use of It.”
As PFAS permeate our environment in different ways, scientists are taking the lead in developing proactive approaches to search for, study, and maybe take the “forever” out of “forever chemicals.”
Arsenic-contaminated groundwater affects more than 230 million people living in 108 countries. About 180 million of these people live in the Indian subcontinent (which includes Bangladesh, Nepal, and Pakistan, in addition to India) and Southeast Asia. The Indian state of Bihar, which borders Nepal, has several regions with extremely high levels of naturally occurring arsenic in their groundwater.
In Bihar, silt from the Himalayas containing arsenic and other heavy metals is routinely deposited in floodplains and seeps into the groundwater below. This phenomenon puts up to 21 million residents in Bihar at risk of consuming arsenic-contaminated water each day. Arsenic is a carcinogen that has also been linked to diabetes, pulmonary disease, cardiovascular disease, and infant mortality.
Though Bihar has close to 600 groundwater treatment units designed to filter out arsenic, a recent study of 98 units found that 90% of them were installed in parts of the state where groundwater arsenic levels were within the World Health Organization’s permissible limits (below 10 parts per billion)—which means almost all the communities that need these units the most still do not have access to them. The research was published in Groundwater for Sustainable Development.
“Some of the areas with these units had reported a higher prevalence of gallbladder cancer, which is associated with arsenic poisoning. But we found that it was the food that was the main source of arsenic exposure, not groundwater,” said Arun Kumar, a study author and senior scientist at Mahavir Cancer Sansthan & Research Centre in Patna, the state’s capital city. “In the last decade, we have observed drastic changes in groundwater arsenic levels in Bihar. Along with that, the cancer burden has also reduced in some parts of the state.”
In another city, Buxar, Kumar and his colleagues observed levels of arsenic of up to 1,900 parts per billion in the groundwater in 2015. But when the researchers retested that region’s water samples last year, the arsenic levels had gone down to 100–200 parts per billion.
“We hypothesize that because Bihar is prone to earthquakes, the seismic activity might have changed the properties of sediments and silt in groundwater. And perhaps, at some stage, those regions with the groundwater treatment units had experienced arsenic contamination,” added Kumar. “It is still a mystery to us” why the levels changed so drastically.
Ditching Groundwater for River Water
Kumar acknowledged that in the past few years, there has been a mushrooming of public and private groundwater arsenic treatment units in regions located within 10 kilometers (6.2 miles) of the Ganges River in Bihar. The majority of the 98 units included in the study were installed by the state government from 2016 onward. The researchers observed that privately owned units underwent regular maintenance, unlike many of the government-run units.
“Much of the previous large-scale groundwater testing conducted in Bihar was limited to the 6-mile stretch on either side of the Ganges River.”
The corresponding author of the study, Laura Richards, a professor of water resources and geochemistry at the University of Manchester, explained that regions close to the Ganges River may have been given higher priority mainly because they are situated along major roads and highways, making them easier to access than inland Bihar.
“Much of the previous large-scale groundwater testing conducted in Bihar was limited to the 6-mile stretch on either side of the Ganges River. The issue with that is that the regions selected for arsenic remediation units were likely based on nonrepresentative spatial sampling of the state, and those locations might not have necessarily covered all areas with arsenic contamination in the groundwater,” said Richards. “Arsenic distribution across the state is really quite heterogeneous.”
The researchers further found that in 10% of the locations where groundwater arsenic treatment units were installed by the state government, high levels of fluoride posed a greater public health risk than arsenic, suggesting that governmental policies were rolled out without site-specific water quality monitoring and testing.
“Alluvial or sand-rich aquifers are the main culprits of arsenic-contaminated water in Indian terrains.”
In addition to arsenic and fluoride, the groundwater in different parts of Bihar has high levels of manganese and iron. Currently, the state has more than 3,000 groundwater treatment units for arsenic, fluoride, and iron. However, Kumar said a better solution would be to look to other sources for drinking water and to ensure water treatment centers are properly maintained.
“People would be a lot safer if they stopped consuming groundwater altogether,” Kumar said. “This is why the state government has started treating and supplying water from the Ganges River to villages. They have already started doing it in two districts and plan on expanding the supply of river water.”
“Alluvial or sand-rich aquifers are the main culprits of arsenic-contaminated water in Indian terrains,” said M. Santosh, a professor at the China University of Geosciences in Beijing who was not involved in this study. “This study clearly shows how we can rectify remedial measures on a local level. We should encourage more such studies on how to tackle this problem.”
—Anuradha Varanasi, Science Writer
Citation: Varanasi, A. (2026), In Bihar, groundwater treatment units were installed in regions that didn’t need them, Eos, 107, https://doi.org/10.1029/2026EO260168. Published on 21 May 2026.
Lead-acid batteries are omnipresent. An integral part of most electric vehicles and all conventional vehicles globally, they also serve as backup energy storage systems in developing countries. But if lead-acid batteries are recycled in smelting units without adequate pollution control measures, they can cause elevated lead pollution that persists in local soils for thousands of years. However, because recycling sites with pollution control measures cost millions of dollars, most efforts are informal and unregulated.
In a recent study, researchers reported that scraping lead-contaminated soil in the vicinity of an abandoned recycling site for used lead-acid batteries and treating it with phosphate was linked to a 22% reduction in the blood lead levels (BLLs) of children who were living close to that site in a Bangladeshi town. The research was published in the International Journal of Hygiene and Environmental Health.
“Informal battery recycling is rampant in Bangladesh.”
“Informal battery recycling is rampant in Bangladesh,” said study coauthor Mahbubur Rahman, an environmental health scientist at the International Centre for Diarrhoeal Disease Research, Bangladesh. “Used lead-acid batteries are broken up and smelted in close proximity to residential and agricultural areas, which exposes those communities to lead emissions that contaminate their soil and water sources.”
Rahman and colleagues analyzed the BLLs of 130 children living close to two recycling sites for used lead-acid batteries (ULAB) in the Tangail District of Bangladesh that were abandoned in early 2019. They also assessed the BLLs of 37 children who did not live anywhere near ULAB recycling sites. The researchers then carried out soil remediation efforts at one of the ULAB sites but not the other. Prior to the work, the team members held informational sessions for the community about the dangers of lead pollution so locals could provide informed consent to participate.
The team observed that following remediation efforts, the lead content of the soil in and around the former battery recycling site decreased from more than 20,000 parts per million to less than 400 parts per million, which was considered acceptable by the U.S. EPA when the study was conducted, from 2022 to 2023. (The EPA reduced the limit to 200 parts per million in 2024.)
The researchers collected and cleaned up soil from children’s play areas, roadsides, and courtyards of 68 households that belonged to the intervention group. A year after the lead-contaminated soil was cleaned up, the 89 children from those households had the most significant decreases in their BLLs: from 90.1 to 70.4 micrograms per liter, a decrease of more than 21%.
“We know for sure that the areas close to abandoned ULAB recycling sites are as contaminated as areas around abandoned lead mines.”
The children in the group who lived close to the second abandoned ULAB recycling site, where soil remediation was not conducted, experienced only about an 8.4% decrease in their BLLs, from 88.5 to 81.1 micrograms per liter. The reduction in the control group’s BLLs could be attributed to a government initiative focused on reducing lead levels in turmeric, which was happening over the same time period as the study, Rahman said.
Anne Riederer, an environmental health scientist at the University of Washington who was not involved in the new study, said the dangers of lead exposure from ULAB recycling sites are well documented.
“We know for sure that the areas close to abandoned ULAB recycling sites are as contaminated as areas around abandoned lead mines. This study fits with the bigger picture of what we have learned to date about cleaning up contaminated sites and how that could improve children’s health,” she said.
A Widespread Issue
Similar studies conducted in Brazil and Bangladesh reported 46% and 35% reductions, respectively, in children’s BLLs following soil remediation initiatives around ULAB recycling sites.
Despite those drastic improvements, the children’s BLLs were still far above the World Health Organization’s threshold of 50 micrograms per liter. “This could mean there are other sources of lead exposure, like paints and cookware items,” said Rahman. “Or the persistently high BLLs could be because of chronic and long-term lead exposure, due to which lead gets deposited deep into the bones for several decades, even if [people] move away from toxic sites.”
Rahman explained that while soil remediation is an effective mitigation measure for lowering childhood lead exposure, it is also labor-intensive and expensive. Though the team identified hundreds of toxic sites borne from informal ULAB recycling, it wasn’t possible for them to remediate the soil at every site.
“The reason why this issue is so widespread is [that] informal recycling is cheap,” he said. “That makes the formal sector reluctant to invest in costly pollution control measures.”
—Anuradha Varanasi, Science Writer
Citation: Varanasi, A. (2026), Cleanup of battery recycling sites may lower childhood lead exposure, Eos, 107, https://doi.org/10.1029/2026EO260120. Published on 15 April 2026.
The coal industry can damage human health in myriad ways via dangerous working conditions and harmful pollution. But the income opportunities offered by the industry can also provide much-needed stability for certain communities, such as those in Appalachia’s coal country.
“Being employed is good for your health, but environmental pollution is bad for your health, and these two things are operating at the same time in some communities,” said Mary Willis, an epidemiologist at Boston University.
The industry, though, is changing. Total coal production in the United States peaked in 2008, and the number of miners has steadily dropped since then.
Total coal production peaked in the United States in 2008, after which the number of coal miners declined, too. Credit: Thombs et al.,2026, https://doi.org/10.1111/ruso.70034, CC BY 4.0
A new study coauthored by Willis and published in Rural Sociology delves into the effects of this decline on life expectancies across the United States and in Appalachia in particular. The results show that a disappearing coal mining industry has mixed effects on health, highlighting the importance of a “just transition”—a shift away from coal mining and toward clean energy that also prioritizes decent work opportunities for those left without a job.
“How do we balance these two conflicting priorities?” Willis said.
Delving into the Decline
Coal production and consumption are linked to many human health harms, including heart disease, asthma, lung cancer, mental illness, and more. But how those health impacts intersect with the broader economic effects of mining has not been well studied.
In the new study, the research team analyzed the effects of the declining industry through the lens of the social determinants of health, or how social structures influence health outcomes.
Researchers analyzed how coal mining impacts life expectancies via three pathways: production, mining labor time, and employment. Credit: Thombs et al., 2026, https://doi.org/10.1111/ruso.70034, CC BY 4.0
To study these effects, the team compared coal mining data from the U.S. Energy Information Administration to life expectancy data from the Institute for Health Metrics and Evaluation at the University of Washington from 2012 to 2019. Life expectancy is a metric that can be responsive to subtle changes in the environment, Willis explained. For example, the decommissioning of a coal-fired power plant a few miles away from a community may not affect residents’ day-to-day life but probably affects the scale of life expectancy across the population.
In coal-producing counties across the United States, the average life expectancy was 1.6 years lower than that in non-coal-producing counties. But the declining coal industry had more nuanced impacts on health in Appalachian communities, the researchers found. As coal production fell and miner labor hours decreased, life expectancy increased. But as the number of jobs available decreased, life expectancy decreased, too.
The findings suggest that the employment and associated economic impacts of a waning coal industry harm health. Previous studies documented similar increases in mortality in other regions where the fossil fuel industry has declined. Such research has indicated that these increased mortality rates may be partially driven by “deaths of despair” from drug and alcohol use and suicide related to economic distress. The association of these factors with mortality rates in coal country, the authors suggest, may be an area for future study.
Understanding that coal mining is associated with some positive economic and health effects is “an important perspective for understanding the sector as a whole,” said Lucas Henneman, an environmental engineer at George Mason University who was not involved in the new study. “It’s a really interesting piece of work.”
“This is just a really complex story that hasn’t been told yet—putting health into the context of these just energy transitions,” Willis said.
The complex reality of the coal industry extends beyond Appalachia. Most of the pollution related to the coal industry consists of toxins released when coal is burned, meaning those who bear the brunt of coal’s health impacts may not be located where coal is mined, Henneman said.
In fact, a 2023 study by Henneman and others found that before 2009, a quarter of all air pollution–related deaths of people on Medicare were attributable to coal burning. From 2013 to 2020, that number dropped to 7%, alongside a drop in coal consumption. A complete picture of how the coal industry affects health should also consider how pollution travels beyond coal country—where it’s burned, how it’s transported in the air, and who ultimately breathes it in, he said.
A Just Transition
“The question is how to provide [jobs] in a way that provides the same level of stability, same kind of income benefits, and isn’t too much of a shock to [communities’] way of life or sense of identity.”
The economic activity of a mine, through direct employment as well as businesses reliant on the mine and miners, “chases away other opportunities,” making the mine the economic backbone of the area, said Jonathan Buonocore, an environmental health scientist at Boston University and a coauthor of the new study. The concept of a just transition aims to ensure that employment opportunities in the wake of the coal industry’s decline reach these communities.
“The question is how to provide [jobs] in a way that provides the same level of stability, same kind of income benefits, and isn’t too much of a shock to [communities’] way of life or sense of identity,” Buonocore said.
Citation: van Deelen, G. (2026), As the coal industry fades, life expectancies in coal country shift, Eos, 107, https://doi.org/10.1029/2026EO260134. Published on 30 April 2026.
On a rocky archipelago in the North Atlantic Ocean, staff at the Faroese Environment Agency and the Faroe Marine Research Institute regularly sample tissues from the North Atlantic long-finned pilot whales that roam the waters around the islands. The archive of these samples stretches back to the 1980s and has helped researchers determine the reach of human-made contaminants in the remote marine environment.
Jennifer Sun is one of those researchers. Sun studies PFAS—per- and polyfluoroalkyl substances, commonly known as “forever chemicals”—at Harvard University and is the lead author of a recently published study that analyzed how these toxic chemicals have accumulated in pilot whale tissue over the past 2 decades.
Using samples of whale tissue collected between 2001 and 2023, Sun and her colleagues measured a parameter called bulk extractable organofluorine, which shows the overall amount of organofluorine-containing chemicals (including PFAS) in the tissue. They then used a more targeted analysis able to confirm the identity of 28 specific chemicals out of thousands of possible PFAS formulations.
The pilot whale tissue showed an expected decrease in the concentrations of older PFAS but an unexpected scarcity of newer PFAS chemicals. Credit: Jennifer Sun
The study’s results showed an expected decrease in the concentrations of older PFAS but an unexpected absence of newer PFAS chemicals. This anomaly could be indicative of an emerging question in PFAS research: Where are the newest PFAS going?
Prolific PFAS
There are two general categories of PFAS. The first includes legacy PFAS such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). Chemical manufacturers produced these compounds in the 1970s, 1980s, and 1990s for products including nonstick cookware and food packaging and in industries such as fabric waterproofing, industrial manufacturing, and firefighting.
Legacy PFAS were phased out in the early 2000s, and novel PFAS were made to replace them. The term “novel” is independent of chemical properties and instead refers to when the chemicals’ production began, though novel PFAS typically have formulations meant to reduce their persistence in the environment. For example, many novel PFAS molecules have shorter chains of fluorinated carbons than their legacy counterparts.
Novel PFAS include possibly millions of different chemical structures, and their production and use are increasing globally.
A generic PFAS molecule includes a compound head connected to a tail of fluorinated carbons. Older PFAS generally have longer tails (seven or eight carbons) than newer ones. Credit: Mary Heinrichs/AGU, after https://bit.ly/pennstate-ext-pfas
In the United States and elsewhere, regulatory structures that limit PFAS production target specific chemicals, such that every new formulation by a company must be tested individually before restrictions are put in place. With companies continually conjuring new PFAS formulations—which environmental advocates often call “regrettable substitutions” for their sometimes harmful effects—understanding the fate and transport of novel PFAS is difficult and time-consuming. Research on the behavior of specific PFAS may be a drop in the bucket when millions of potential PFAS, with millions of potential behaviors, pose current and future risks to people and the environment.
Scientists like Sun are determined to untangle how the fate of these new chemicals differs from their predecessors. As Sun expected, the phaseout of legacy PFAS was reflected in the pilot whale tissue she tested. These results are good news; they clearly show that the bans on legacy PFAS are working.
“We’re still finding [older] compounds, but clearly, they are no longer as abundant in the environment as they used to be, which is a positive,” said Bridger Ruyle, an environmental engineer at New York University who studies PFAS and assisted Sun and her coauthors in deciding which methods to use for the new study.
But Sun and her colleagues also expected an overall increase in concentrations of novel PFAS—after all, production of these chemicals is higher than ever, and researchers finally had the analytical tools to catch them.
“The inference is, if it’s not in the whales, and it’s not in the ocean…where is it?”
That wasn’t what they found. Instead, all but two of the emerging PFAS they tested for were virtually nowhere to be seen in the whale tissue, leaving the scientists leading the study to wonder where novel PFAS were accumulating or if instrumentation was limiting their detection.
“We do know that the novel PFAS are being produced, which means they’re going somewhere. Where they are, and how exposed people and other wildlife are, is not as clear,” Sun said.
“The inference is, if it’s not in the whales, and it’s not in the ocean…where is it?” asked Elsie Sunderland, an environmental scientist at Harvard University and coauthor of the new study.
Sun and Sunderland’s question—asking where novel PFAS are going—is one scientists are probing from multiple angles. Those who study particle transport are asking how novel PFAS might travel through Earth’s water and air. Those on the chemistry side of the investigation are deducing how novel PFAS might break down. And those who monitor environments are looking for traces of novel PFAS in various corners of Earth.
The answers to their questions have direct, practical implications for human and environmental health and could indicate whether a growing proportion of harmful PFAS may be ending up in close proximity to humans—where we work and eat and breathe.
A Toxic Legacy
The chemical properties of PFAS have made the chemicals useful since the 1940s. These same properties also make them highly persistent—the most durable types may not break down in the environment for several thousand years.
PFAS are linked to certain cancers and other human health harms. Much of the available data linking PFAS to poor health come from analyses of legacy PFOA and PFOS. They show an association between increased exposure to these chemicals and altered immune and thyroid function, liver and kidney disease, reproductive system disruptions, and more.
Chemical manufacturers phased out production of legacy PFAS after scientific evidence emerged associating PFAS and human health harms, businesses began to lose money in massive lawsuits, and regulations tightened. Novel PFAS were intended to show properties similar to legacy PFAS but were meant to break down more easily in the environment (lower persistence) and accumulate less easily in living tissue (lower bioaccumulative ability), though studies have shown mixed results about whether novel PFAS are actually safer for humans or break down more easily.
Because PFAS production data are often proprietary, scientists who study PFAS, like Sun, must rely on partial inventories of PFAS production or reverse-engineer those numbers from observations in the environment.
“We call it chemical Whac-A-Mole.”
Without a clear list of the chemical structures of novel PFAS, scientists don’t always have the analytical standards necessary for routine detection. And once scientists do understand the behavior of a PFAS chemical, it may be quickly replaced by another, unknown alternative. “We call it chemical Whac-A-Mole,” Sunderland said.
Legacy PFAS tend to have a high affinity for water and typically end up in the ocean, the place scientists refer to as the chemicals’ “terminal sink.” Many legacy PFAS also entered the ocean through atmospheric transport such as rain or snow. But because of the sheer number of chemical formulas and the chemical differences between legacy and novel PFAS, the pathways that novel PFAS take through the environment are less clear.
Tracking the movement and accumulation of novel PFAS in the environment is crucial for understanding how these chemicals may affect ecological and human health.
Still, the science is inconclusive about whether novel PFAS are moving or accumulating differently than their legacy counterparts, whether they have a different terminal sink, and where that terminal sink may be.
Close to Home
One possible answer to the question of the missing novel PFAS may have to do with geography. The chemicals may not have reached pilot whales in the Faroes because something about the new chemistry has led them elsewhere in the environment. To Sun, evidence suggests “that a lot of these novel PFAS, which we know are being produced, may not be transporting out into this more remote environment either at all or as quickly.”
Novel PFAS might be accumulating closer to their sources—and closer to us. “It may simply be that some of the replacement PFAS don’t make it all the way out into the open ocean. But if they are still in the terrestrial environment and the near-coastal environment, then wildlife and people who live close to the sources can be exposed, said Frank Wania, an environmental chemist at the University of Toronto Scarborough.
For example, one study monitored PFAS in coastal beluga whales in Canada’s St. Lawrence Estuary, relatively close to human communities and PFAS manufacturing sources. The study showed increasing concentrations of unregulated novel PFAS in whale tissue from 2000 to 2017, while concentrations of legacy PFAS declined.
The suggestion that novel PFAS are accumulating close to human communities is supported by measurements of PFAS in human tissue, too. Studies show that a high proportion of detectable organofluorine chemicals in human tissue are increasingly unidentifiable, suggesting that some of the novel PFAS production “is in us,” Sunderland said.
Far and Away
Though there are some indications that novel PFAS may be retained closer to human communities, there are also reasons to think some novel PFAS chemistries have resulted in substances that can actually travel farther and more easily than their legacy counterparts.
Anna Kärrman, an environmental chemist at Örebro University in Sweden, said that some novel PFAS may be more easily transported in the environment: “The more novel chemistries are increasing the properties of being very mobile in water, very mobile in the atmosphere, and not necessarily very bioaccumulative.”
The mobility of novel PFAS was on full display in a 2020 study that Sunderland coauthored, in which researchers reported detecting hexafluoropropylene oxide-dimer acid, a novel PFAS chemical more commonly known as GenX, in the Arctic for the first time. GenX, produced by chemical manufacturer Chemours, was meant to replace the legacy compound PFOA. The 2020 study suggested GenX “has already moved quite a bit,” said Rainer Lohmann, a marine geochemist who leads the STEEP (Sources, Transport, Exposure and Effects of PFAS) Center at the University of Rhode Island.
A pulley system mounted on a red beam pulls a small envelope filled with water along a string. Credit: Thomas Soltwedel
The 2020 study also found higher concentrations of PFAS in the Arctic Ocean’s surface water, suggesting that the atmosphere was a particularly important transport pathway for chemical transport. This idea is supported by studies of High Arctic ice caps, which experience contamination only from atmospheric sources, and polar bear tissue. Atmospheric transport of novel PFAS is a subject “at the edge” of PFAS research, Sunderland said.
Wherever researchers look, they’re finding that atmospheric transport is an important pathway by which some PFAS, especially PFAS precursors—chemicals that break down in the environment and become PFAS (either novel or legacy)—move. One idea called the PAART (precursor atmospheric and reaction transport) theory was developed by Scott Mabury, an environmental chemist at the University of Toronto, and others. The PAART theory proposes that many of the harmful PFAS that end up in the most remote parts of Earth are the result of the breakdown of volatile precursor PFAS that have traveled in the atmosphere.
According to Lohmann, atmospheric transport means the ocean remains a terminal sink because many novel PFAS transported in rain or snow will ultimately be deposited in the ocean.
In this scenario, the question of why novel PFAS are not bioaccumulating in Faroese pilot whales remains a mystery. While Lohmann suggests the novel compounds simply don’t accumulate in living tissue, Sunderland isn’t sure that’s the whole story: “As apex predators, the whales are sentinels for what is available and being taken up from the ocean,” she wrote in an email. “Since we don’t see [novel PFAS], it seems unlikely there are large quantities of these chemicals present.”
Profuse PFAS
Another possible explanation for the surprising results of Sun’s whale study could be that there’s just a lag; that is, novel PFAS will end up in Faroe Island pilot whales someday but haven’t yet. Chemicals that could eventually end up in the ocean may be temporarily trapped in soils or recycled back into terrestrial ecosystems via sea spray aerosols, for example.
“The delay we are seeing in the ocean response may in fact be [PFAS] precursors being retained in source zones,” Sunderland wrote in an email. These chemicals may be “taking a really long time to be transformed into more mobile compounds.”
In their pilot whale study, Sun and her colleagues modeled the transport of PFAS to the subarctic and found a 10- to 20-year lag existed between the production of a legacy PFAS compound and its detection in whale tissue. We’re still within that range for many novel PFAS. Sun said she would have expected them to show up in pilot whale tissue by now if they behaved like their legacy counterparts, though it’s possible that it has taken time for the volume of novel PFAS production to ramp up, increasing the time it would take for the substances to be detected in tissues.
The anomaly documented in the pilot whale study has led researchers to call for more investigation (and perhaps greater regulation) of novel PFAS. Credit: Bjarni Mikkelson
Still, the number of possible novel PFAS chemistries—again, there could be several million different compounds—makes it difficult to generalize how these new substances are, as a group, moving through the environment. “Because the exact structures of all [novel] PFAS remain unknown, some compounds may simply not be captured by the methods used,” Heidi Pickard, an environmental engineer at the consulting firm Ramboll and coauthor on the new whale study, wrote in an email.
Another reason novel PFAS are harder to study is that companies release lower concentrations of more kinds of the chemicals, rather than the “monstrously high” emissions of some legacy PFAS in the 1970s–1990s, noted Mabury, who was not involved in the new pilot whale study.
A New Regulatory Approach
According to Sun and Sunderland, cataloging differences between novel and legacy PFAS misses the broader point: We simply need to produce less PFAS. We’ve known for decades that PFAS harm human health, and some scientists have even argued that humans’ continual production and release of novel chemical compounds could drive Earth beyond a “safe operating space.”
“Researchers are critical for exposing the problem. But that, to me, is not the central issue here. The central issue here is a societal issue.”
Where scientists probe next may be less urgent than how policymakers decide to tackle the PFAS problem, Sunderland said: “Researchers are critical for exposing the problem. But that, to me, is not the central issue here. The central issue here is a societal issue.”
Chemical manufacturers are actively creating novel PFAS all the time. Kärrman, for example, has noticed patent applications for PFAS compounds with chemistries that “are nothing like we have seen before” that may start entering our environment in 5 or 10 years.
To Kärrman, that’s a reason for governments to push for chemical regulation based on properties such as persistence and bioaccumulation, rather than the chemical-by-chemical formula used in most countries, including the United States.
Such an approach has gotten traction in Europe via a proposal by the European Chemicals Agency to restrict the entire class of PFAS chemicals. The proposal is still under evaluation, and a final decision is expected by the end of the year.
In the United States, PFAS regulation and remediation are a key aspect of the Trump administration’s Make America Healthy Again movement, according to the EPA, and the federal government and some states already limit the concentrations of individual PFAS in drinking water. However, the EPA also said it planned to weaken some of those limits last year.
“We’re in a cycle of picking these regrettable alternatives [to legacy PFAS] and then figuring out that it was regrettable decades later,” Sunderland said. “We’re never going to catch up using this chemical-by-chemical approach.”
Citation: van Deelen, G. (2026), Chemical companies are churning out new PFAS. Where in the world are they ending up?, Eos, 107, https://doi.org/10.1029/2026EO260136. Published on 30 April 2026.
The spread of antibiotic resistance, a growing threat to global health that causes millions of deaths annually, is typically blamed on the overuse of drugs in hospitals and in the food industry. However, a new study published in Nature Microbiology suggests that normal geological processes could be accelerating the development of new resistances.
Soil microorganisms naturally produce antibiotics as a form of chemical warfare to compete with each other. When soils dry out, these natural compounds become more concentrated because there is less water to dilute them. Like a dosage increase, this concentration can create a harsher environment, killing sensitive microbes and sparing those with the capacity to resist. This phenomenon, in turn, is an evolutive driver that favors the appearance of new and more effective resistance genes.
“If you have more antibiotics in your environment, only the organisms that can withstand it…can resist it.”
To test whether this mechanism is having real genetic effects, Xiaoyu Shan, a microbial ecologist and postdoctoral researcher at the California Institute of Technology (Caltech), and colleagues looked at soil samples under controlled conditions as the samples transitioned from a wet state to a desiccated one. They found that as the soil dried, the presence of genes related to antibiotic production and resistance spiked, suggesting that drought leads to a rapid escalation in the subterranean biological arms race. Importantly, they did not look for pathogenic bacteria specifically, only for resistance genes, which can be present in a variety of microbes, whether those microbes are pathogenic or not.
“Drought leads to this elevation of antibiotic producers and bacteria that are resistant,” said team member Dianne Newman, a professor of biology and geobiology also at Caltech. “It’s a pretty simple idea: If you have more antibiotics in your environment, only the organisms that can withstand it…can resist it.”
Alternative Explanations
However, there could be other potential explanations for the observed increase in antibiotic-producing and antibiotic resistance genes, according to Enrique Monte, a microbiologist at the Universidad de Salamanca in Spain who wasn’t involved with the new study. For instance, arid soils are naturally more diverse than humid soils, making it common to find a more diverse gene pool in the ground, Monte said. In addition, the mere presence of antibiotic genes might not result in an actual release to the environment, or a release could happen in dosages that are too small to cause noticeable effects. “There are antibiotics that are volatile; they escape into the air, so they never reach a therapeutic concentration to kill others,” Monte said.
The authors, however, took some precautions to show that the increase in antibiotic resistance genes was actually a biological response to environmental stress. For instance, they also tracked other genes that should remain unaffected or decline under desiccation. As expected, genes that are needed for basic survival remained stable, while genes responsible for bacterial movement declined in dry soil, where mobility is restricted. Even some species that were not favored by desiccation saw an increase in resistance-related genes, “which is even stronger evidence,” Shan said.
Geographic Limitations
As the researchers combed through publicly available metagenomic data libraries, they had to select collections with strict control of all variables and in which the only changing factor was water content. That limited the analysis to five locations: two grasslands and a sorghum field in California; a forest in Valais, Switzerland; and a wetland in Nanchang, China.
The scarcity of locations might limit how extrapolable these results are, said Fiona Walsh, a microbiologist at Maynooth University in Ireland who was not involved with the work. “There are thousands of high-quality metagenomes available online with excellent metadata. I would really like to see a comparison where they apply their analysis to a broader map of global metagenomic data to see if they reach the same conclusions,” she said.
From the Soil to the Hospital
Drier regions consistently showed a higher number of resistant bacteria cases in hospitals, even after adjusting for confounding factors such as local income.
The study also suggests that dry soils might be a hidden driver of clinical cases of antibiotic resistance worldwide. The authors combined hospital data on the number of cases of resistant infections from 116 countries with the local aridity index, which measures temperature and precipitation, for each location. They found a strong correlation: Drier regions consistently showed a higher number of resistant bacteria cases in hospitals, even after adjusting for confounding factors such as local income.
However, the authors admitted that this is only a correlation effect and doesn’t prove causation. “It motivates follow-up research to see how environmental concentration weighs against human overuse and poor stewardship,” Newman said.
Even this correlation could be a stretch, according to microbiologist Sara Soto, head of the Global Viral and Bacterial Infections Programme at the Instituto de Salud Global de Barcelona. At the end of the day, she said, the authors have soil data from only five locations in three countries, and they are not tracking the specific bacterial varieties that make people sick, only resistance genes.
For the thesis to be solid, Soto said, the ideal approach would have been to contrast hospital strains from a specific area with soil data from that same region during the same drought episode. “Making such a vast inference—that what happens in the soil of one location affects what happens in a hospital elsewhere—is a big leap,” she said.
The authors, however, point out that resistance genes from soils can eventually make their way into human pathogens. Microbes have the capacity to share genetic material across species—a process known as horizontal gene transfer. In their analysis, the team identified specific resistance sequences that appeared to have been transferred between soil bacteria relatively recently, perhaps within the past decade. How they are reaching hospitals remains a matter for a future study, they said.
As droughts increase in numerous regions in the face of climate change, this selective pressure within soil ecosystems is expected to intensify. Though these findings do not show that drought directly puts drug-resistant pathogens in hospitals, they still suggest that a drying climate could set the scene for an increase in antibiotic resistance, the researchers report.
Citation: Barbuzano, J. (2026), Antibiotic resistance might get a boost from droughts, Eos, 107, https://doi.org/10.1029/2026EO260132. Published on 29 April 2026.
Login
