Features WATER
As more of these drugs escape wastewater treatment, scientists are sampling rivers and other waterways to understand their impact ALEXANDRA A. TAYLOR, C&EN WEST COAST
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Arion Leahigh samples water from Hunting Creek in Alexandria, Virginia, and the surrounding area.
ior could put the fish at greater risk for predation. Of course, the concentrations that the University of Utah team studies are not what would be found in the environment—typically in the range of nanograms per liter to micrograms per liter. But lower concentrations could still have some effect, Peterson says. It’s also possible that if multiple opioids lurked in the water at and that the fish undergo withdrawal low concentrations, they could have an symptoms when the drug is removed additive impact, but studies have yet to (Behav. Brain Res. 2017, DOI: 10.1016/j. confirm this effect in fish. In particular, bbr.2017.08.001). researchers worry about the potential enThe researchers were studying addicvironmental effects of the synthetic opioid tion rather than environmental exposure fentanyl, which the National Institute on during this experiment. So they released Drug Abuse estimates is 50–100 times as a concentrated plume potent as morphine and of 6 mg/L hydrocodone which caused the sharpO solution into the fish’s est increase in human N N tank—a level that would deaths from opioid use definitely show a behavin 2017. ioral effect if one existed Studying changes but not kill or sedate the to fish behavior at low Fentanyl fish. The zebrafish in this environmental constudy would swim over an underwater centrations, though, is difficult. So far, platform that triggered the release of the some studies find evidence for altered drug, regardless of where the platform behavior, while others do not. A 2019 was placed. When the opioid was withstudy found that ecotoxicologists interheld from the tank, the fish showed “a lot preting the same data can arrive at very of the physiological responses that you different conclusions (Sci. Total Environ., would see with any kind of withdrawal,” DOI: 10.1016/j.scitotenv.2019.02.090). Peterson says. It’s also difficult to properly simulate Peterson and Bossé observed that the conditions fish would experience in once the fish had been conditioned to the wild. In moving water, opioids and self-administer the drug, they would untheir metabolites are likely not evenly dergo risky behaviors—such as swimming dispersed, so pinpointing their precise into shallow water—to dose themselves. levels is problematic. But a handful of “Changes in behavior have consequences,” labs scattered across the US are up for Peterson says. In the wild, this behavthat challenge.
hose hardest hit by the opioid epidemic are the people who become addicted—and the family members and friends who deal with the fallout. In 2017, opioids contributed to about 47,600 deaths by overdose in the US, according to the Centers for Disease Control and Prevention (CDC). And that year, 23 states saw significant increases in opioidrelated deaths over the previous year. But some researchers worry that another, lesser casualty of this epidemic could be the environment. As opioid use continues to proliferate, the drugs enter more people’s bodies, where they break down into metabolites—often other opioids— that end up in wastewater. Scientists have detected opioids downstream of wastewater treatment plants and are concerned about the potent drugs’ possible effects on organisms who live in those waters. But until recently, these researchers didn’t know much about the extent of the problem. Wastewater treatment plants are not required to monitor or report opioids in their discharge. So several labs across the US have taken matters into their own hands. They have begun measuring how much of these drugs is present in rivers and streams as a first step toward understanding what effect the compounds might have on the environment. What’s prompted scientists’ concern about opioids in the environment is that humans aren’t the only animals who respond to the drugs. A 2017 study by Randall T. Peterson and Gabriel D. Bossé at the University of Utah found that, when presented with options, zebrafish will willingly dose themselves with an opioid
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Tracking opioids in the environment
Examining effluent
the city’s discharge. Morphine, hydromorphone, and oxymorphone showed up from time to time but were usually below the detection limit of the team’s instruments. Boles says large creatures like people have no reason to worry about drinking water with contaminants at these ultralow levels. Furthermore, from October 2016 to December 2017, the levels of all the prescription opioids that Boles’s lab was tracking dropped below detectable levels. John Buford, assistant plant superintendent, says CWTP optimized its biological disinfection process in April 2015, switching from a purely oxidizing process to an oxidizing and reducing process. In November 2016, the plant replaced its old ultraviolet disinfection machine with a new one. Tennessee’s opioid prescribing rate had been declining since 2010, another factor that may have contributed to the drop in their readings. Cookeville is a small city, but Boles says areas that are more densely populated are associated with higher discharge of pharmaceuticals and personal care products (PPCPs) in their wastewater. “I think what I’ve found is a very small part of a larger overall picture,” Boles adds. And studies in this field are just beginning. Boles is working to further improve the team’s process and would like to start sampling for fentanyl. Fentanyl use may increase as states crack down on prescription opioids. Boles says fentanyl could pose more environmental risk because it’s so potent; it’s also more dangerous to handle and can be difficult for labs to obtain for testing.
Cookeville is a city of about 33,000 located in one of the top 15 states for opioid deaths as of 2017: Tennessee. Water from the Cookeville Wastewater Treatment Plant (CWTP) runs out to Pigeon Roost Creek, goes through Falling Water River, and eventually joins Center Hill Lake, which is where the city draws its drinking water. “Anything that we ingest eventually gets released into the wastewater system,” says Tammy Hatfield Boles, an environmental scientist at Tennessee Tech University. The treated water is then heavily diluted before making it back to the city’s taps. Boles, who studied incoming and outgoing water at CWTP for 2 years, presented The Potomac River flows from West her results during a Division of EnvironVirginia’s Potomac Highlands to the mental Chemistry symposium at the Amer- Chesapeake Bay. Along the way, it passes ican Chemical Society Spring 2019 National Washington, DC, which in 2017 ranked Meeting in Orlando, Florida, on April 2. fourth among US states in opioid deaths Her group worked closely with CWTP. “We love it when we don’t have to go into the influent and effluent and bail water,” Boles says. The plant provided Boles with samples, which her group then tested in its lab. She and her team used solid-phase extraction (SPE) and liquid chromatography– tandem mass spectrometry (LCMS/MS) to analyze samples of influent and effluent. From four sampling events ranging from July 21, 2015, to March 22, 2016, Boles’s lab detected an average Tammy Hatfield Boles’s lab uses this solid-phase extraction of 5.58 ng/L of hydrocodone setup to monitor opioids in wastewater. “It’s not high tech, but and 4.74 ng/L of oxycodone in it works well,” she says.
Probing the Potomac
C R E D I T: TA MM Y H AT FI E LD B O LES
per 100,000 people, according to the CDC. Arion Leahigh, a fifth-year PhD student in Gregory Foster’s lab at George Mason University, has set her sights on tracking opioids in the Potomac. She visits sampling locations in the DC metro area by boat or by foot, using a portable, battery-operated pump to collect water and a grab sampler to obtain sediment. Leahigh comes from a small town in Pennsylvania that’s been hurt by the availability of illicit drugs. She’s helping optimize her lab’s processes for detecting opioids and other PPCPs. Like Boles, Leahigh uses a combination of SPE and LC-MS/MS to assess the concentrations of opioids in the water. She also reported her findings during the recent ACS meeting in Orlando. She found maximum values ranging from 5.18 to 83.36 ng/L of the opioid tramadol at different locations along the Potomac. In addition to opioids, her team has turned up caffeine and nicotine in almost every sample, plus blood pressure medication, antidepressants, anti-inflammatories, and antihistamines. Leahigh’s group is working to obtain effluent samples from local wastewater treatment plants so they can understand where the drugs they’re finding are coming from. Currently, they don’t know which ones are coming out in which effluent. If they don’t find a drug downstream, it could be because their method can’t detect it, the drug has broken down, or it’s not evenly dispersed. “Are they in the water? Are they settling down to the sediment? Are they breaking down and becoming harmless?” Leahigh asks. Once they know what the plants are putting out, they can start to understand the differences in concentrations. Leahigh’s lab is at the Potomac Science Center, which is located directly on the Potomac. The team plans to put out an autosampler to measure fluctuations throughout an entire tidal cycle. Right now, the researchers are beholden to the tides because they’re using a boat to access sampling sites, which requires a certain depth of water. She hopes this new strategy will help them determine whether concentrations fluctuate with the tide or at certain times of day.
Studying the sound In the Pacific Northwest, some researchers are forgoing water samples altogether for monitoring opioids. Jennifer Lanksbury runs the Washington Department of Fish and Wildlife’s Puget Sound Mussel
APRIL 22, 2019 | CEN.ACS.ORG | C&EN
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C R E D I T: DAV I D TOT H
Mussels are suspended in this antipredator cage, ready to be placed in Appletree Cove in the Puget Sound. Monitoring program, one of several longterm programs that monitors local wildlife under the Toxics-Focused Biological Observing System. The system tracks contaminants in various food webs throughout the Puget Sound using indicator species such as English sole, Pacific herring, and Chinook salmon. Native mussels are the system’s nearshore indicator. By looking at the tissues of these animals, the scientists can determine the relative amounts of drugs in the surrounding water. Mussels are filter feeders, so “you’re much more likely to find a contaminant in mussel tissues than you are to pick it up in water or even sediment,” Lanksbury explains. “We call them our little aquatic vacuum cleaners.” Unlike fish, mussels don’t have a liver with which to metabolize contaminants, “so the contaminants in their tissues reflect pretty well what’s in their local environment.” The mussels grow at an aquaculture farm off the shore of Whidbey Island, about 90 km northwest of Seattle. Volunteers bag the mussels in nets suspended in antipredator cages and transplant them to up to 100 sites throughout the sound every other October. The mussels remain in the water for about 3 months before they’re removed and sent back to the lab, where about half the mussels from each cage are blended into a slurry and sent off to various analytical facilities for testing. The program typically looks at ongoing contaminants, such as polycyclic aromatic hydrocarbons, and legacy contaminants, such as polychlorinated biphenyls and the insecticide dichlorodiphenyltrichloroethane. But in 2017, Lanksbury teamed up with Andy James, a senior research scientist at the University of Washington Tacoma, to screen some of the mussels for PPCPs. Of the 18 samples they screened, 3 tested positive for oxycodone—the first indication of opioid contamination in the Puget Sound. The samples came from three of the most urban sites: two in Seattle and one in Bremerton;
for food at Puget Sound’s aquaculture at its highest, oxycodone was present at farms, located in more rural areas, are 1.5 ng/g of the sample’s wet weight, which really clean. For another, James points out Lanksbury and James consider a low conthat a person would need to eat more than centration. While most legacy contami100 lb (45.4 kg) of the contaminated musnants enter the sound from stormwater sels to reach a therapeutic dose of oxycorunoff, Lanksbury suspects PPCPs are done—and that eating that many mussels entering the water mostly via wastewater would surely lead to other ailments. effluent. “The message is that there are Wastewater plants in the US are regmultiple sources of contamination in nearulated nationally by the Environmental shore Puget Sound,” she says. “Depending Protection Agency’s National Pollutant on which chemical you’re interested in, it Discharge Elimination System, which does could be more one source than the other.” not require them to test for opioids or Lanksbury and James are more conother pharmaceuticals in cerned about some of the their discharge. For the conother PPCPs their screen H3CO taminants they are required turned up, including antito remove, such as ammobiotics, selective serotonin nia, the plants are highly reuptake inhibitors from O antidepressants, alkylphenol N CH3 effective, Boles and Leahigh HO H say. Lanksbury would like to ethoxylates from detergents, O pinpoint how much of each and the chemotherapy drug PPCP is coming from each melphalan, a possible carOxycodone plant, but those data aren’t cinogen that was present at available yet because many of these efforts half the mussel sites at surprising levels. “We don’t want to see chemotherapy drugs have only just begun. As opioid use continues along its upward in the environment,” Lanksbury says. trajectory, Boles says she’s concerned about Like Boles, Lanksbury and James stress what’s going into the water. “We have to that their findings are not cause for conthink about the future,” she says. “We have cern for human health. For one thing, to make sure that our water and all of our these mussels were planted in urbanized resources are sustainable.” ◾ areas. Lanksbury says the mussels grown
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