Scientists found cocaine in freshwater shrimps when testing for chemicals in UK rivers.
Researchers from King’s College London, working with the University of Suffolk, tested at 15 sites across Suffolk and found cocaine at all of them.
The study, published in Environment International, found other illicit drugs such as ketamine, pesticides and pharmaceuticals were also widespread in the shrimp that were collected.
Dr Leon Barron, from King’s College London, said: “Such regular occurrence of illicit drugs in wildlife was surprising.
“We might expect to see these in urban areas such as London, but not in smaller and more rural catchments.
“The presence of pesticides which have long been banned in the UK also poses a particular challenge as the sources of these remain unclear.”
Lead author Dr Thomas Miller, from King’s College London, said concentrations were low and the potential for any effect was “likely to be low”.
Professor Nic Bury, from the University of Suffolk, said further research is needed to determine whether the presence of cocaine in aquatic animals is widespread in the UK and abroad, or a particular issue for Suffolk.