According to research published in the journal Science of the Total Environment, there are other unintended victims of human drug use: eels.

The study, which was conducted on European eels, found that as in much of the world, a great number of pharmaceuticals have made it into waterways, impacting marine life. Turning their attention to recreational drugs, the research team from Italy’s University of Naples Federico II discovered that concentrations of drugs such as cocaine have also been found in some of the world's waterways.

Having found trace amounts of cocaine in European eels, the team set out to investigate the drug’s impact on the eels. In their research, farm raised eels were placed in a lab tank for 50 days with the same low-level concentrations of cocaine found in some rivers (roughly 20 nanograms per liter). These eels, according to the researchers, seemed more hyperactive, swimming faster than their “sober” brethren.

Researchers also dissected a number of eels and discovered that moving the previously drug-exposed eels to clean water for almost two weeks did nothing to reverse the skeletal muscle damage they experienced from drug exposure. Researchers also believe that drug-exposure would likely impact eel migration.

“In addition to sufficient energy reserves, the eel needs a healthy skeletal muscle and an efficient aerobic metabolism, in order to complete successfully its migration," the team wrote in their study.

Another concern, according to researchers, is reproduction. Cocaine exposure affects cortisol and dopamine levels, thereby impairing reproduction as well as preventing an eel from reaching sexual maturity. This is in addition to the dangers already plaguing the swimmers, including habitat loss, overfishing and pollution.

Considering that the concentration of drugs found in rivers, streams and other bodies of water will be felt across all marine life, researchers also caution that the impact could be felt by humans as well.

"Since the skeletal muscle is the edible part of the eel," those consuming European river eels could also be ingesting cocaine, though probably not enough to be dangerous.

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