Cocaine flushed into rivers is making critically endangered eels “hyperactive” and threatening their survival, new research suggests.
Traces of the drug routinely make their way into Britain’s waters after passing through users’ bodies, and could be causing serious health problems for some fish, according to the study.
Previous research has found residues of illegal drugs including cocaine, amphetamines and ecstasy in European lakes and rivers, including the Thames.
The drugs end up in surface waters in highly populated areas after passing through sewage treatment plants, but scientists say little is known about the ecological impact.
In the new study, biologists at the University of Naples Federico II put European eels in water containing a small dose of cocaine – similar to the amount found in rivers – for 50 days.
They found the fish “appeared hyperactive” compared to eels which had not been kept in waters containing cocaine.
The drug accumulated on the brain, muscles, gills, skin and other tissues of the cocaine-exposed eels, researchers said.
The eels’ skeletal muscle showed evidence of serious injury, including muscle breakdown and swelling, which had not healed 10 days after they were removed from the drug-contaminated water.