Drug pollution becomes addictive for fish

Everyone knows about plastic pollution and the issue of oil, pesticides and fertilizers running off into natural bodies of water. However, the issue of drug pollution – a sure sign of out of control human population growth – is a type of pollution that is less often discussed.

Prescription drugs like Prozac and birth control have been a problem that our current waste water systems are simply not up to solving. These drugs cause health and behavior changes in many fish and can be harmful to entire ecosystems.

Unfortunately, the damage does not stop with medicinal drugs. Illegal recreational pharmaceuticals are also a growing source of drug pollution that poses a threat to aquatic life. 

A team of researchers at the University of Southern Bohemia and the University of Life Sciences in Prague set out to investigate the impact of methamphetamines on brown trout, Salmo trutta. 

The scientists placed trout in a tank with levels of methamphetamines similar to that sometimes found in the wild for two months. After the period of exposure to the drug pollution, the fish were moved to a tank with freshwater, lacking methamphetamines and looked for signs of withdrawal. 

The fish were also offered the choice between freshwater and water laced with methamphetamine on a regular schedule for ten days to see if they would seek out the drug again. The observations produced strong evidence that the trout exposed to methamphetamines had indeed become addicted to the drug. 

There are clear health risks to drug addiction and the scientists worry that the fish might gather near discharges of wastewater – places unhealthy to them – just to get a fix.

It is possible that there are additional, less obvious health problems caused by fish exposure to illegal drug pollution. Until water treatment becomes better equipped, this will likely remain a threat for the foreseeable future.  

“Our results suggest that emission of illicit drugs into freshwater ecosystems causes addiction in fish and modifies habitat preferences with unexpected adverse consequences of relevance at the individual and population levels,” wrote the researchers. “As such, our study identifies transmission of human societal problems to aquatic ecosystems.”

The study is published in the Journal of Experimental Biology.

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By Zach Fitzner, Earth.com Staff Writer