How Bad Is Drug Pollution in Rivers?

The amount of drug pollution in major rivers around the world - including the Thames in the UK - could be having a seismic impact on the flora and fauna which call such habitats their home, according to a new study. The research, published in the journal Science of the Total Environment, exposed European eels to trace amounts of cocaine for 50 days and observed concerning results.

While the affected eels gave an outward appearance of similar health levels as those not exposed to the drugs, analysis of their bodies revealed another side to the story. The results indicated that drug exposure could have a detrimental impact on the eels’ ability to undertake the 3,700-mile trip necessary for them to spawn and complete their life cycle, potentially endangering future generations.

A controlled high

In order to determine how recreational drug use was impacting animal life downstream of discharge points, the team behind the new study recreated real-world conditions in a laboratory. They exposed the eels to 20ngL^-1 of cocaine (comparable concentrations to those found in heavily polluted rivers like the Thames and the Amo River near Pisa in Italy) for 50 days continuously.

The eels displayed hyperactivity but otherwise seemed healthy enough. However, analysis of their bodies found that the drug had accumulated in various different parts, including skin, muscles, tissues, gills and even the brain. Their hormone activity was interrupted, and certain muscles exhibited signs of swelling and even breakdown.

Perhaps most concerning of all, cocaine consumption enhances cortisol levels in the body, which is a hormone related to stress that encourages the consumption of fatty deposits. Given that eels must undertake a near 4,000-mile journey towards the end of their lives, they must build up sufficient fat stores to make the trip possible in the years before. Therefore exposure to cocaine could disrupt the timing of this journey or even make it impossible altogether.

The tip of the iceberg

Of course, this study only focused on the impact of one drug on one species of animal. There are plenty of other contaminants in our rivers, including other drugs, heavy metals, pesticides and antibiotics. A cocktail containing such ingredients could have untold impacts on all manner of flora and fauna in rivers across Europe and beyond.

One possible solution to the problem is improved wastewater treatment facilities, such as the water supply and effluent treatment system recently installed in the Portuguese Algarve. When these facilities are better equipped to weed out harmful elements and become ubiquitous around the world, it will become less and less likely that drug residue can find its way into animal and plant habitats in any concentration.

Obviously the best way to clean up contaminated waterways is to prevent the problem happening in the first place. Improved wastewater treatment would be a great solution, but eradicating drug abuse in the first place would be even better. However, given that widespread legislation prohibiting its use is already in place, it’s unlikely that curbing cocaine use – or other harmful substances, for that matter – will happen anytime soon.