In a new study, researchers detected high concentrations of human antidepressants and their metabolized remnants in the brain tissue of 10 fish species – including bass and walleye – common to the Great Lakes region of the United States. The drugs enter rivers and lakes from treatment plants and sewage overflows, scientists say.
These active ingredients from antidepressants, which are coming out from wastewater treatment plants, are accumulating in fish brains. It is a threat to biodiversity, and we should be very concerned.
These drugs could affect fish behavior. We didn’t look at behavior in our study, but other research teams have shown that antidepressants can affect the feeding behavior of fish or their survival instincts. Some fish won’t acknowledge the presence of predators as much.
The researchers said that levels of antidepressants they found do not pose a danger to humans who eat the fish, especially in the U.S., where most people do not eat organs like the brain. But the risk that the drugs pose to biodiversity is real, and scientists are just beginning to understand what the consequences might be.
The percentage of Americans taking antidepressants rose 65 percent between 1999-2002 and 2011-14, according to the National Center for Health Statistics. Wastewater treatment facilities have failed to keep pace with this growth, typically ignoring these drugs, which are then released into the environment, Aga says. In general, wastewater treatment focuses narrowly on killing disease-causing bacteria and on extracting solid matter such as human excrement. Antidepressants, which are found in the urine of people who use the drugs, are largely ignored, along with other chemicals of concern that have become commonplace, Aga said in a statement.
These plants are focused on removing nitrogen, phosphorus, and dissolved organic carbon but there are so many other chemicals that are not prioritized that impact our environment. As a result, wildlife is exposed to all of these chemicals. Fish are receiving this cocktail of drugs 24 hours a day, and we are now finding these drugs in their brains.
Her new study looked for a variety of pharmaceutical and personal care product chemicals in the organs and muscles of 10 fish species: smallmouth bass, largemouth bass, rudd, rock bass, white bass, white perch, walleye, bowfin, steelhead and yellow perch in the Niagara River, a vital conduit that connects two of the Great Lakes, Lake Erie and Lake Ontario, via Niagara Falls.
Antidepressants stood out as a major problem: These drugs or their metabolites were found in the brains of every fish species the scientists studied. The antidepressants that Aga’s team detected in fish brains had accumulated over time, often reaching concentrations that were several times higher than the levels in the river.
Bottom line: New research has detected high concentrations of human antidepressants and their metabolized remnants in the brain tissue of 10 fish species common to the Great Lakes region of the United States.
Eleanor Imster has helped write and edit EarthSky since 1995. She was an integral part of the award-winning EarthSky radio series almost since it began until it ended in 2013. Today, as Lead Editor at EarthSky.org, she helps present the science and nature stories and photos you enjoy. She also serves as one of the voices of EarthSky on social media platforms including Facebook, Twitter and G+. She and her husband live in Tennessee and have two grown sons.