River perch subjected to Oxazepam, a drug used to treat anxiety in humans, lose their fear of exploring dangerous places and become gluttonous and antisocial, according to a study published in Science .
Scientists from Umeå University (Sweden) did not study the effect of anxiolytics on fish out of curiosity. Many European rivers are polluted with the remains of various drugs, as treatment plants have little capacity to remove certain chemicals from wastewater. Although we know the effects of these drugs on humans, so far few researchers have evaluated their consequences on ecosystems.
The fish were exposed to concentrations of Oxazepam similar to those found in the rivers of Sweden. “Generally, these fish are shy and hunt in schools . It is a survival strategy. ”, Explains Tomas Brodin, one of the authors. “However, the perch swimming in Oxazepam became much more fearless.” The fish under the effects of the anxiolytic left the school to hunt on their own, a behavior that can be dangerous since when the perch go in groups they are more difficult to catch by their predators.
Also, these fish became more voracious and ate faster. “Now we have to study the consequences that this behavior can have. If some fish start to eat more, this change can affect species composition , for example, or lead to an increase in algal blooms, ”explained the researcher.
At the moment there are no effective methods for removing residues of certain drugs from wastewater. Meanwhile, scientists recommend not flushing expired drugs down the toilet and prescribing greener drugs , in cases where this type of alternative exists. It is also essential to carry out more studies that identify the effects of the different products on the ecosystems they reach.
