It turns out that becoming shrimp scampi or part of a shrimp cocktail is no longer the only threat looming for these crustaceans. Through no fault of their own, England’s freshwater shrimp are trying to kick a drug habit. A new study has demonstrated that shrimp found in bodies of water in rural Suffolk are consistently testing positive for cocaine as well as other controlled or prohibited substances.

Researchers at King’s College London and the University of Suffolk published the paper in the journal Environment International after taking samples from 15 different locations across five river catchments in Suffolk. Drugs like cocaine and ketamine were found in the shrimp, along with pesticides and other micropollutants. Researchers also found lidocaine, a local anesthetic used to “cut” cocaine.

The levels are low, researchers say, but potential damage to these tiny Tony Montanas will need to be assessed with further study. This research does raise the question of how shrimp are testing positive for illegal drugs in the first place. When a human ingests drugs, their urine can contain trace metabolites that enter the wastewater system. One theory is that nearby wastewater treatment plants have discharged this type of contaminated waste into the Suffolk's rivers, though their filtration processes should prevent pharmaceuticals or their metabolites from getting through. It’s possible that sewer overflow or improper system connections are to blame.

While the shrimp don’t appear to be affected, that hasn't been true of all animals. In the UK, a study of the effects of cocaine in eels demonstrated that it can accumulate in their brains, muscles, skin, and gills, causing swelling and hormone disruption that could affect their migrations and reproductive processes. Water contaminated with antidepressants can also influence behavior. Crabs exposed to Prozac, for example, became more aggressive.

[h/t BBC]