Anxiety-moderating drugs that reach waterways via wastewater create fearless and asocial fish that eat more quickly than normal.
Many drugs leave our bodies unaffected, and residues from them are therefore found in wastewater. Low concentrations of drugs are often found downstream from sewage treatment plants. Today we test how dangerous drugs are to humans, but our knowledge of the environmental impacts of drugs is limited. For the first time, scientists have now been able to show how the behavior of fish is affected by involuntary medication.
Researchers have examined how perch behave when they are exposed to the anxiety-moderating drug Oxazepam. The changes were obvious in drug concentrations corresponding to those found in waters in densely populated areas in Sweden.
“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,” explains ecologist Tomas Brodin, lead author of the article.
The drug made the fish braver and less social. This means that they left their schools to look for food on their own, a behavior that can be risky, as school formation is a key defense against being eaten by predatory fish.
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