A group of British scientists drug-tested freshwater shrimp from 15 sites across five rivers in Suffolk County, a rural area northeast of London. Their results, published in the journal Environment International, showed that all the shrimp contained trace amounts of cocaine, as well as the drug ketamine (an anesthetic sometimes used as a party drug) and a banned pesticide called fenuron.
The researchers said the drugs likely made their way into rivers and fresh water after human consumption; cocaine can pass from urine into our wastewater. Then — especially if raw human sewage is left unfiltered and untreated — the drug can flow from our sewage systems into surrounding aquatic ecosystems.
“Such regular occurrence of illicit drugs in wildlife was surprising,” Leon Barron, a coauthor of the study, said in a press release. “We might expect to see these in urban areas such as London, but not in smaller and more rural catchments.”
The study authors said they couldn’t draw any conclusions about what effects these river pollutants might have on the shrimp or the animals that eat them. They did say, however, that the detection of “several pesticides that no longer have approval in the EU” warrants further investigation.