Shrimp Are Testing Positive for Cocaine and Scientists Don't Know Why

Scientists investigating the contamination of wildlife with drugs have found cocaine in every shrimp they studied, as well as other chemicals such as banned pesticides.

To carry out their study published in the journal Environment International, scientists collected shrimp samples in July 2018 from 15 sites across five river catchments in the non-metropolitan county of Suffolk on the east coast of England, U.K.. These included Gipping, Alde, Deben, Stour and Waveney.

Cocaine was the most commonly found drug and identified in every sample, as well as the anesthetic lidocaine. This is often used by dealers to bulk up the cocaine, according to the study authors. The scientists believe cocaine could have entered the water because of leakages or overflows from sewers.

Pesticides banned in the U.K. were also discovered, including fenuron. Ketamine, the animal tranquilizer which is used as a party drug, was also identified, as well as the opioid medication Tramadol and an antidepressant.

Dr. Leon Barron, senior lecturer in forensic science at King's College London and co-author of the study said: "Such regular occurrence of illicit drugs in wildlife was surprising."

The team might have expected to find drugs in urban areas like the UK capital London, he said, but not in rural areas. Pinpointing the source of banned pesticides remains unclear and poses a challenge to experts, he said.

Dr. Thomas Miller lead author of the study at King's College London commented: "Although concentrations were low, we were able to identify compounds that might be of concern to the environment and crucially, which might pose a risk to wildlife.

"As part of our ongoing work, we found that the most frequently detected compounds were illicit drugs, including cocaine and ketamine and a banned pesticide, fenuron. Although for many of these, the potential for any effect is likely to be low."

Study co-author professor Nic Bury from the University of Suffolk said: "Whether the presence of cocaine in aquatic animals is an issue for Suffolk, or more widespread an occurrence in the UK and abroad, awaits further research.

"Environmental health has attracted much attention from the public due to challenges associated with climate change and microplastic pollution. However, the impact of 'invisible' chemical pollution (such as drugs) on wildlife health needs more focus in the UK as policy can often be informed by studies such as these."

The contamination of wildlife with illicit substances is not isolated to rural England. Last year, separate research by the Washington Department of Fish and Wildlife discovered the opioid oxycodone in shellfish off the coast of the state for the first time.