International Partnership Uncovers Neuroactive Pharmaceutical Buildup In Freshwater Systems

Baylor University, University of South Bohemia scientists measure bioaccumulation in Czech Republic freshwater systems

Researchers from the University of South Bohemia in the Czech Republic and Baylor University have uncovered first-of-its-kind field evidence demonstrating that neuroactive pharmaceuticals are accumulating in developing freshwater fish beyond internationally recognized safety thresholds. Applying real field research involving control groups of developmental fish both upstream and downstream of wastewater treatment, researchers tracked aquatic life from developmental to free-swimming stages and identified elevated bioaccumulation in fully realistic environmental conditions.

The findings were published in Environmental Science & Technology, an internationally leading American Chemical Society-published journal.

“This research helps us consider ways to protect our fisheries and their environments, with implications for recreation, water quality and the sustainability of health care. Most studies in this area are performed in laboratory settings, and with larger or older organisms. This study identifies active molecules, which have been contraindicated for pregnant mothers, accumulating above acceptable thresholds with implications for the lifelong development of fish.” - Bryan W. Brooks, Ph.D.

“This research helps us consider ways to protect our fisheries and their environments, with implications for recreation, water quality and the sustainability of health care,” said Bryan W. Brooks, Ph.D., Distinguished Professor of Environmental Science and Public Health at Baylor University. “Most studies in this area are performed in laboratory settings, and with larger or older organisms. This study identifies active molecules, which have been contraindicated for pregnant mothers, accumulating above acceptable thresholds with implications for the lifelong development of fish.”

Brooks is an author on the study, which was led by research partners at the University of South Bohemia: Kateřina Grabicová, Ph.D., associate professor of fishery, and Roman Grabic, Ph.D., associate professor of fishery. This unique international research partnership utilizes the strengths of researchers at both institutions to advance research that distinctly advances the “Pro Mundo” charge of the Baylor University motto: Pro Ecclesia, Pro Texana, Pro Mundo.

“At Baylor, we are called to pursue research that is Pro Mundo – for the good of the world,” Provost Nancy Brickhouse, Ph.D., said. “By moving beyond the laboratory and into natural environments, Dr. Brooks and his colleagues in the Czech Republic have provided critical insights into how human activity impacts our ecosystems. This work underscores our commitment to stewardship and to generating knowledge that fosters a healthier planet.”

The University of South Bohemia is a public research university located in České Budějovice, Czech Republic, which features the South Bohemian Research Centre for Aquaculture and Biodiversity of Hydrocenoses /CENAKVA/.

“Partnering with an R1 university such as Baylor University represents an exceptional alignment of complementary expertise,“ said Vladimír Žlábek, Ph.D., University of South Bohemia Vice-Rector for International Relations. “By combining our expertise, the University of South Bohemia and Baylor University are able to deliver scientifically robust answers to some of today’s most urgent environmental challenges.”

Implications of bioaccumulation of neuroactive drugs in fish
The World Health Organization has noted an increase in global consumption of neuroactive pharmaceuticals since the COVID-19 pandemic, prompting an examination of the effectiveness of treatment by wastewater systems by Baylor and South Bohemia researchers. As humans take and excrete or dispose of medications in wastewater treatments, their presence within treated water is growing.

Some neuroactive drugs have long been discouraged for pregnant women due to their ability to cross the maternal placental barrier into developing fetuses, a breach which can impact future development. Fish brains, which share many receptor and enzyme characteristics with the human brain, are at risk for the same types of developmental issues from bioaccumulation of neuroactive drugs.

By tracking the fish from eggs into their early free‑swimming phase, the researchers discovered that neuroactive pharmaceuticals – compounds used to treat conditions like depression, anxiety or cognitive decline – were accumulating inside the young fish. Several of these compounds exceeded internationally recognized safety thresholds for bioaccumulation, meaning the levels in the fish were higher than what regulators consider acceptable for water quality.

“For many reasons, we want to keep fish alive and healthy in our rivers,” Grabic said. “We studied species like trout or salmonids that are important to their ecosystems, important for food and to industries in the U.S., Central Europe and more. If we don’t have healthy fish, there are many impacts.”

Researchers on this team broke further ground through an added step to gather deeper and repeatable results – incubating fish eggs directly in the stream both above and below a wastewater treatment plant. This approach allowed scientists to observe how developing fish are exposed to pharmaceuticals under fully natural conditions.

“Streams are highly impacted by treated water, so we had special incubators where we placed fish eggs in treated wastewater-affected creeks and let them grow in real conditions,” Grabicová said. “We sampled fish and determined bioaccumulation, the stages of growth, mortality and sex differential in fish and had control groups upstream to measure the differences.”

The results raise important questions about how these chemicals might influence fish development, behavior, and long‑term population health. Brooks and colleagues note the point of the research is not to stigmatize neuroactive drugs, but to provide data that can support the proper disposal of unused drugs, lead to innovation for more sustainable healthcare, and promote healthy freshwater water systems and fisheries.

“Our observations were unexpected,” Brooks said, “and we anticipate this study will stimulate future efforts to understand long-term organism impact and to protect the fisheries for the future.”

About Baylor University
Baylor University is a private Christian University and a nationally ranked Research 1 institution. The University provides a vibrant campus community for 20,000 students by blending interdisciplinary research with an international reputation for educational excellence and a faculty commitment to teaching and scholarship. Chartered in 1845 by the Republic of Texas through the efforts of Baptist pioneers, Baylor is the oldest continually operating University in Texas. Located in Waco, Baylor welcomes students from all 50 states and more than 100 countries to study a broad range of degrees among its 12 nationally recognized academic divisions. For more information, visit www.baylor.edu.

About University Of South Bohemia
University of South Bohemia (USB) is a modern public university located in České Budějovice, Czechia. We educate about 10,000 students at eight different faculties in more than 200 programs, including bachelor's and master's degrees as well as doctoral programs. At USB you will benefit not just from the modern and dynamic environment but also from the individual approach to students that our staff consider essential. The University of South Bohemia is an attractive destination for students, scientist and an excellent calling card for graduates. The campus includes many state-of-the-art facilities, including South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses /CENAKVA/ at the Faculty of Fisheries and Protection of Waters. For more information, visit https://www.jcu.cz/en/.