When Chemicals Go to the Dark Side

Opposite page: Sampling for per- and polyfluoroalkyl substances (PFAS) in a stream that wastewater discharges into. Photo courtesy of Linda Lee. Half a century ago, in response to burning rivers and other high-profile environmental disasters, the U.S. Congress passed the Clean Water Act (CWA) as a means to protect waterways from sea to shining sea. Commemorating that landmark legislation, the Journal of Environmental Quality this year has published a collection of papers celebrating the CWA. CSA News magazine is highlighting some of that work through a three-part series. In September, we looked at research (https://doi.org/10.1002/csan.20828) on how constructed wetlands can decrease nutrient runoff on tile-drained agricultural fields. In October, we examined what scientists have learned about the benefits and challenges of using biosolids to fertilize crops, rehabilitate contaminated landscapes, and boost soil health (https://doi.org/10.1002/csan.20853). This final story in the series discusses recent research on emerging contaminants—chemicals suspected of harming people and the environment. From “forever chemicals” to disinfection by-products, and from pharmaceuticals to the lithium batteries that we too often toss in the trash, these pollutants are resulting in unintended consequences that scientists are working hard to understand. Chemicals can be convenient, useful, even lifesaving. We love them when they keep food from sticking to stuff or help us apply lipstick with ease. We love them when they power our cars, computers, and cell phones. We love them when they protect us from diseases. We love them when they make our drinking water safe. But once we’re done with them—once we have thrown them in the trash, washed them down the sink, or flushed them down the loo—they can become a lot less loveable. Some benign compounds transform into harmful ones. Some toxic molecules defy degradation. One-time helpmates can even turn deadly when they end up where we never intended—in our soil, food, tap water, and air. Welcome to the ominous world of emerging contaminants, a vast group encompassing hormones, novel pesticides, nanoparticles, microplastics, disinfection by-products (DBPs), pharmaceuticals and personal care products (PPCPs), and per- and polyfluoroalkyl substances (PFAS). Although “emerging” suggests something novel, some of these pollutants have been around for decades. But building the scientific case for regulating these contaminants is a time-consuming, costly, and often controversial process. Alex Chow, a professor in the Department of Forestry and Environmental Conservation at Clemson University, believes it is high time we learned from our mistakes. In a recent article (https://doi.org/10.1002/jeq2.20405) published in the Journal of Environmental Quality (JEQ), Chow argues that society must be more proactive about preventing contamination from chemicals whose effects may not yet be understood. Over the decades, he has watched the same story unfold over and over as if stuck on repeat: A new compound with promising applications is synthesized; it is embraced by the public and hailed by scientists, perhaps even winning a Nobel Prize (as did DDT and plastics). Eventually, the compound reveals its dark side, leaving scientists and policymakers with a costly environmental and public health mess. He now sees the same story playing out with lithium. Alex Chow collects water samples at the University of California–Berkeley’s Sagehen Field Creek Station for a study on nutrients and pyrogenic dissolved organic carbon in surface water runoff. Photo courtesy of Alex Chow. “Our Society does not recognize it, does not learn from it,” says Chow, an SSSA and ASA member. He advocates taking a more proactive approach to managing the lithium widely used in batteries before it becomes the next Nobel Prize-winning environmental menace. Soil coring for transport studies of per- and polyfluoroalkyl substances (PFAS). Photo courtesy of Linda Lee. Below we introduce you to a trio of scientists who have dedicated their careers to mitigating the fallout from three classes of emerging contaminants: DBPs, PFAS, and PPCPs. Motivated by a love of the environment, they study these compounds from multiple angles—formation and transformation, fate and transport, remediation and prevention. Between the shifting regulatory landscape, the need to detect pollutants at ever more minute concentrations, and how intricately these compounds are enmeshed in our lives, the field keeps researchers on their toes. “I feel like we’re working in an ever-changing landscape,” says Purdue University researcher Linda Lee, an SSSA and ASA member who has been in the field for decades, “a rapidly changing landscape.” As a girl, fish net in tow, Heather Preisendanz would hunt for newts, salamanders, and—her favorite—frogs in the wetlands, vernal pools, and lakes of northern New Jersey. In support of her zeal for amphibians, her family even built a pond in the backyard. “I remember hatching tadpoles as a kid and just being so amazed that this creature could start as an egg, hatch into a tadpole, and then metamorphose into a frog,” recalls Preisendanz, an SSSA member. “These were creatures that I cared about protecting. And once I realized how sensitive they can be to all the pollutants in the environment, then that turned into, I guess, what it is now.” What it is now is a career devoted to keeping bad stuff out of water. As an associate professor of agricultural and biological engineering at Penn State University, Preisendanz studies emerging contaminants like PPCPs. The COVID-19 pandemic presented her team with a unique opportunity to study what happened to our wastewater while millions of people were taking drugs to treat the virus at home and in hospitals. For a study recently published in JEQ (https://doi.org/10.1002/jeq2.20398), Preisendanz and her colleagues spent a year mid-pandemic collecting samples of wastewater as it entered (influent) and then left (effluent) two treatment facilities in Pennsylvania. One is the facility that treats Penn State’s wastewater to the state’s “class B” standard before repurposing it for irrigation on a tract of university land called the Living Filter. The other is the facility that serves the surrounding area, including a hospital, which treats wastewater to the state’s “class A+” standard before using some for irrigation and discharging the rest into a nearby stream. Preisendanz’s team tested the samples for SARS-CoV-2, the virus that causes COVID-19, as well as for prescription and over-the-counter drugs used to treat the virus. They then looked for correlations between what they found in the wastewater, COVID infection and hospitalization rates, and the number of students on campus. “We started at the most basic,” Preisendanz says. “Do we see any trends with the COVID case numbers? And then: Do we see any trends with hospitalizations?” They observed some correlations they expected: For the university samples, for example, antibiotics showed up when students were on campus but not when they weren’t. However, when COVID infection rates rose in the community, they did not see a corresponding bump in over-the-counter drugs in wastewater. Rather, variations in those levels appeared to be seasonal. Similarly, when COVID hospitalizations increased, they saw in their samples no rise in the prescription drugs used to treat the disease. Treated wastewater effluent is sprayed at Penn State’s beneficial reuse site, called the “Living Filter.” This diverts the wastewater from Spring Creek and allows the soil to act as a natural filter for any chemical residuals that remain in the wastewater. Penn State’s Heather Preisendanz has studied the effluent for emerging contaminants. Photo by Heather Preisendanz. At first, this left the scientists scratching their heads. Then they drilled down to more specific data on the number of COVID patients on ventilators, who typically receive dexamethasone. That’s when the correlations began to emerge from the data. Kristin Cochran, a Ph.D. student in the lab of University of South Carolina chemist Susan Richardson, conducts a liquid-liquid extraction of drinking water to analyze disinfection by-products (DBPs). Photo courtesy of Susan Richardson. Demand for disinfectants surged during the COVID pandemic, adding to the wastewater stream more chemicals that, under the right circumstances, could transform into harmful disinfection by-products (DBPs). “You really had to look specifically for what the medicine was being used to treat, and then the numbers made sense,” Preisendanz says. More head scratching ensued when the team detected traces of remdesivir in campus wastewater: There were no hospitalized COVID patients on campus. After a bit of sleuthing, however, they learned that a lab was running experiments using the drug around the time they detected it in the wastewater. When comparing treated wastewater, the team found that the community facility, which treated the wastewater to a higher standard, did a better job at removing some pharmaceuticals than the campus facility. They also found that, in the effluent at both facilities, levels of some pharmaceuticals remained high enough to threaten aquatic organisms. To Preisendanz, the finding highlighted how important it was to filter the effluent through soil before it would eventually reach those organisms, as both facilities do, or to release it into streams that can immediately dilute it with fresh water. Unfortunately, notes Preisendanz, not all areas of the country can offer those ecosystem services. “In more arid portions of the U.S., that’s just not true,” she says. “There, effluent is a larger portion of the streamflow, and so there is less opportunity for the streams to dilute out contaminants. If what we’re seeing holds true to other wastewater treatment facilities where these chemicals are persisting and there is less dilution happening, then potentially the risk could be higher in those areas.” Preisendanz’s work had previously focused on, as she describes it, “what’s at the end of the pipe and where it goes after it is released into the environment.” But this new study also showcases the epidemiolocal applications of wastewater and what it can tell you about the health of the population that generated it. By monitoring wastewater for pathogens or pharmaceuticals, she says, treatment facilities can alert communities about potential public health issues—and help scientists get more bang for their research buck. “These are not cheap compounds to analyze for,” Preisendanz says. The data could be leveraged through collaborations with public health experts, universities, prisons, and municipalities. “It opened the window for us to think about what we are doing differently, as having connections back to human health on the upstream side, and not just the implications after the fact.” In addition to drugs and the virus itself, there’s another class of compounds COVID helped boost in wastewater: disinfectants. Demand for disinfectants surged during the pandemic, adding to the wastewater stream more chemicals that, under the right circumstances, could transform into harmful DBPs. Disinfectants such as chlorine, widely used in public water systems, react with naturally occurring organic matter, bromide, and iodide to create DBPs, some of which have been linked to cancer and other health problems. According to Susan Richardson, a leading expert in DBPs and a professor of chemistry at the University of South Carolina (USC), more than 700 variations of the compounds have been discovered in drinking water to date. Many were first identified in her own lab, including the recent discovery of an entirely new class of them. Richardson has water in her blood, she says. She grew up on St. Simons Island off the Georgia coast where she swam, crabbed, and explored the maritime forests. These days, she uses her off time to scuba dive in tidal rivers and hunt for fossils. Her discoveries include a six-inch-tall megalodon tooth: She was so excited to find it, she recalls, that she screamed into her regulator. “You’re holding a piece of an animal in your hand that was alive millions of years ago,” Richardson says. “It’s like holding history.” Her day job also involves hunting in water. But the specimens she looks for in drinking water are even harder to spot than dinosaur fossils—and a lot more dangerous. Richardson has spent more than three decades ferreting out DBPs using mass spectrometry, first at the USEPA, and more recently at her own lab at USC. Richardson is also concerned about PFAS; she has developed a new method that screens for them by measuring the total organic fluorine in a sample. But she reserves the bulk of her scientific energy for DBPs, which she believes pose the much greater threat. Like PFAS, they are found in most waters but in far higher concentrations—micrograms per liter rather than nanograms. The epidemiologic data, she argues, indicate DBPs are much more toxic to people than PFAS. “We’ve got bladder cancer, we’ve got a little bit of colorectal cancer,” Richardson says. “And then there’s some more recent studies that show miscarriage and birth defects.” Richardson worries DBPs are losing ground to PFAS in the competition for funding and public awareness. To understand this, it helps to know how the USEPA makes tough choices about which contaminants to regulate in drinking water. The process, managed through the Safe Drinking Water Act (or SDWA, which followed the CWA by two years), takes place in five-year cycles. The National Primary Drinking Water Regulations (NPDWR) currently cover dozens of contaminants, including 11 DBPs. The agency periodically updates a contaminant candidate list, the first step for considering a compound for regulation. Some candidates end up on a much shorter list of contaminants that public water systems are required to monitor. Based in part on that data, the USEPA selects a few new compounds to regulate every cycle. Dr. Tamie Veith, a research scientist with the USDA-ARS who collaborates with Penn State’s Heather Preisendanz, downloads hydrologic and water quality data from a monitoring station in Pennsylvania’s Halfmoon Creek watershed. The monitoring station records data every 15 minutes for water level, temperature, dissolved oxygen, and rainfall. Photo by Heather Preisendanz. When, at the end of 2021, the USEPA published its latest list of contaminants to monitor, all but one of the 30 pollutants–lithium–were PFAS. The agency had to pick which poisons to target with its limited resources, and it picked PFAS. Many saw the move as long overdue: Currently, the USEPA doesn’t regulate any PFAS in drinking water (although it recently issued new health advisories). While disappointed by the USEPA’s choices, Richardson continues to build her case against DBPs, like a prosecutor determined to nail a crime ring. One key challenge has been finding the worst of the bunch. “There are definite human health effects, but we still don’t exactly know which DBP’s are the culprits,” Richardson says. “That’s what’s been driving me.” Recently, Richardson narrowed in on those culprits. With a team that includes longtime collaborator Michael Plewa, now a professor emeritus of genetics at the University of Illinois Urbana-Champaign, she produced what the authors call the most comprehensive investigation of drinking water toxicity to date. They collected drinking water from across the U.S. that had been impacted by factors such as agricultural runoff, seawater, wastewater, and algal blooms. Then, using mass spectrometry, Richardson’s team tested each sample for 72 DBPs, many of which had originally been discovered by her lab. After characterizing the samples, she sent extracts to Plewa, who exposed them to mammalian cells. The team then correlated the data to see which caused the most damage. Richardson had a pretty good idea which compound would prove the worst offender: iodoacetic acid, a DBP she had discovered in 2004. She recalls the thrill of spying the pointy peak that denoted the new chemical as it jutted up from the x axis of her mass spec results like a tooth from a dino’s jaw. Penn State lab technician Bill Clees filters a wastewater effluent sample that will be analyzed for pharmaceuticals. Photo by Heather Preisendanz. “I had looked for them, hunted for them in the past, didn’t see them,” she remembers. “And all of a sudden, we’re seeing them big as you please in drinking water.” As with other DBPs, she knew it was a disinfection by-product because the chemical shows up in treated drinking water but not in the source water. After discovering its unique chemical fingerprint and confirming its makeup, she sent a batch to Plewa for toxicology tests. “Oh my God,” he reported, as Richardson recalls. “Iodoacetic acid is the most genotoxic thing I’ve ever looked at. was like an off on my cell In the recent toxicity team that iodoacetic with another group called were important of drinking water correlated the most with the observed toxicity of the drinking waters class is by the one of the DBP classes the USEPA does shows no the scientists In other the USEPA the a few while the DBP off the the side, Richardson a of the toxic they would be for the USEPA to with are having to turn to quality water potential DBP from or other to Richardson. Recently, she has been water from South Carolina lakes by In a published this she and her found that, when water as little as 15 of the the of DBPs some of the most than runoff to the algal Richardson Unfortunately, those now not help for many years to if all that that be to because to up the from the she says. The of with a that have been true for other scientists emerging contaminants. 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They are to their and in like makeup, and where their are courtesy of With her a new mass began PFAS, and never looked Over decades, she has studied the compounds in wastewater, drinking water, and at the she once called home where decades of have in the She with Purdue and health scientists to their harmful effects on and as well as and used as animal to on In one recent she and her its from to She even and has been a treatment on carbon that PFAS. Her research as as the compounds PFAS are to their and in like makeup, and where their are There are to of PFAS out says, on how you They are the of the chemical to their They but could to Alex Chow, a professor in the Department of Forestry and Environmental Conservation at Clemson and more are key to lithium he says. Photo courtesy of “It really hard for to PFAS out of their products because in their facility from or are still being used for some says. She She has the same in her own lab. of organic we we have to it for In the U.S., the USEPA has been PFAS including over the next few years to PFAS and other emerging contaminants in drinking water. The agency released new drinking water health for some PFAS, them to the levels of per for the class called and per for the class called part per is hard to is one in the of water it takes to and are the most of PFAS and the most In the USEPA issued a to both as substances under the Although and still the U.S. in products from other have them. But they are still in this the U.S. by a as has One group of PFAS found in food and other U.S. products is not yet these compounds end up in the portion of what out of wastewater treatment can be used as while the from or But once the PFAS in those biosolids can on a of their own as and her recently The research team examined what out of biosolids over a other they observed that the of group that includes the candidates and the far what had been in the biosolids is the of other PFAS like The toxic with these “That’s we PFAS says. “It’s PFAS to The surrounding the fate and transport of PFAS in biosolids has some communities to or even its suggests taking a few back to see the we need to is out in what to apply them, and are there that we can PFAS from the says. the idea that they be or is the of what we to for to be The harmful effects of she are of than those of “We need to on up the areas contaminated by of and biosolids and not all the PFAS to be that you your says. “We’ve a lot of in to be more are and can be hard to people can on where to regulatory and there are a lot of there are on emerging contaminants. One may be But on this the scientists More funding for this and at keeping pollutants out of the to will The in PFAS funding across is up the field says. a lot and not What it means is that be to a lot more in all areas.” Penn State’s Preisendanz, for example, has to her emerging contaminant to PFAS. She and was on Preisendanz’s Ph.D. at are on an study on PFAS in well water, the source of drinking water for of Preisendanz also a recent study the PFAS of decades of irrigation at Penn State’s Living Her team detected PFAS across its with on While levels were they drinking water levels being by the for and as well as the USEPA’s new health about the of with treated wastewater. is key to the public and says. I to see is being to with the and that have them,” she says. to get every including the to that their choices can make even at the group has a for people who to products with Purdue to to a for the side, has or is in the of PFAS in food and other are could also boost lithium says Chow, which the USEPA’s on lithium batteries as a and more are key to lithium he says, which is to of people in the U.S. have potentially harmful levels of the in their water to the U.S. think lithium is and because at he says. if we them they will get at higher and higher Then I will a In our is celebrating the Clean Water with two new In the first Dr. Alex Chow discusses how we can a proactive approach to lithium In the Dr. discusses years of biosolids research in us at or through your for to never an