Mood-changing drugs enter waterways, affect fish, study finds
Courtesy of Umeå University, Science and World Science staff
Some medicines that end up in the world’s waterways after being used are affecting fish behavior, according to a new study.
Tomas Brodin of Sweden’s Umeå University and colleagues found that wild European perch ate faster, became bolder and acted less social after exposure to an anxiety-moderating drug known as Oxazepam.
|Perch. (Courtesy Ben Christensen)
Residues of the drug often wind up in natural aquatic systems after people consume it, the researchers said. They’re excreted, flushed down the toilet, treated at wastewater treatment plants, and end up in the water unchanged.
Brodin and colleagues dosed wild perch with amounts of Oxazepam equivalent to those found in Sweden’s rivers and streams. Their results, they said, suggested that even small amounts of the drug can alter the behavior and foraging rates of these fish.
“Normally, perch are shy and hunt in schools. This is a known strategy for survival and growth. But those who swim in Oxazepam became considerably bolder,” said Brodin, lead author of the report, published in the Feb. 15 issue of the journal Science. The affected fish left their schools to seek food on their own, a behavior that can be risky, he explained; they also ate more quickly.
“We’re now going to examine what consequences this might have. In waters where fish begin to eat more efficiently, this can affect the composition of species, for example, and ultimately lead to unexpected effects, such as increased risk of algal blooming,” said Brodin.
“The solution to the problem is not to stop medicating ill people but to try to develop sewage treatment plants that can capture environmentally hazardous drugs,” added environmental chemist Jerker Fick, a co-author of the study.
The scientists added that the findings should be seen as a pointer about what might be underway in many waters around the world, though fuller studies are required before any far-reaching conclusions can be drawn.
- Psychiatric Meds in Water Supply May Alter Fish Behavior – U.S. News & World Report (health.usnews.com)
- Drugs Laked Into Rivers Make Fish Antisocial (news.yahoo.com)
- Study: Anxiety Drugs Found In Fish Could Have Evolutionary Consequences (washington.cbslocal.com)
- Drug passed on to fish boosts their confidence (smh.com.au)
- Pill to Gill: Antianxiety Drugs in Flushed into Water May Be Making Fishes Fearless (scientificamerican.com)
- Anxiety Drug in Water Makes Shy Swedish Fish Greedy (bloomberg.com)
- Drug residues ‘alter fish behaviour’ (bbc.co.uk)