Drugs used to treat anxiety and depression are building up in rivers and altering the behaviour of wild freshwater fish, scientists have found.
Significant amounts of Oxazepam, which is widely used to treat anxiety, are being flushed into rivers from sewage works. The concentrations are too low to be considered a health risk to humans but a study has shown they can affect fish.
Drugs like Oxazepam can be excreted from the body intact and persist in treated effluent water.
Researchers in Sweden found that relatively low concentrations of the drugs commonly found in rivers in countries including the UK can cause European perch to act bolder, eat faster and behave less sociably. The scientists believe the subtle behavioural changes seen under experimental conditions indicate how the wider freshwater ecology could be affected by this kind of environmental pollution.
The solution isn't to stop medicating people but to develop plants that can capture environmentally hazardous drugs, said scientist Jerker Fick.