Does any of your medication get washed away through the water system? If so, your medication could lead to aquatic life having a very exhilarating day indeed.

Research from Umeå University, Sweden has shown how an “unusually high” concentration of anti-anxiety drug, Oxazepam, in a river in Sweden has caused fish to exhibit a number of strange changes to behaviour.

Whilst water purification and treatment systems are supposed to remove contaminants such as drugs, many have slipped past, leading to worry that other drugs may be harming aquatic life.

Fish take up the drug through the tissues in their muscles, meaning that they are incredibly sensitive to even small concentrations of the drug.

The drugged fish appeared to leave their protective shoal formation, preferring to swim individually. When the concentration of drug was increased, the fish went one step further and travelled through to unknown places far more willingly than their normal counterparts.

Secondly, fish drugged to any concentration of oxazepam became far more hungry, and more innovative in finding their food.

It is not certain that oxazepam is the sole cause of the erratic behaviour, or whether circumstances are to blame, concern has nonetheless been raised as to the ecological effects of washing drugs out into the oceans. It is hoped that this will again raise the argument for regulation of aquatic pollutants.

DOI: 10.1126/science.1226850