Researchers have discovered that benzodiazepines, such as Valium and Oxazepam, which are being flushed into rivers from sewage works, build up in concentrations that can significantly affect behavior of wild freshwater fish.
The researchers found small concentrations (around 0.58 micrograms per litre) of Oxazepam in the River Fyris in Sweden, that caused the European perch to be less sociable, eat more and become more adventurous.
‘We found distinct behavioural changes in the perch, even at low levels of exposure. The changes can be seen as both beneficial or detrimental depending on the ecology,“ said study leader Tomas Brodin.
”The fish became bolder and fed faster, which is a good thing if there are no predators around, but could be risky if there are,“ he added.
”It could also have a knock-on effect on the surrounding environment. If the fish eat more zooplankton, then there is less in the water. Zooplankton eat algae, so without them there could be algae blooms.“
According to the researchers, the found concentrations are comparable to those of benzodiazepines reported in other European and American waters.
The scientists are worried about the consequences of this kind of hidden environmental pollution and argue that some thing needs to be done to reduce the concentrations that get into our waterways.
“The solution to this problem isn’t to stop medicating people who are ill but to try to develop sewage-treatment plants that can capture environmentally hazardous drugs,” said Jerker Fick of Umeå, who was part of the team.
Photo: Wikimedia C0mmons
Brodin, T., Fick, J., Jonsson, M., & Klaminder, J. (2013). Dilute Concentrations of a Psychiatric Drug Alter Behavior of Fish from Natural Populations Science, 339 (6121), 814-815 DOI: 10.1126/science.1226850
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