Fish are swimming in drugs, says researcher

Water contamination | The full effect of pharmaceuticals present in waterways on fish is unknown

Fish are on Prozac in some North American waterways downstream from cities. 

They’re also on Zoloft and swimming in various chemicals that exist within the urban water cycle.

Bryan Brooks, a biological sciences professor from Baylor University in Waco, Texas, discussed some of his research into urban water contaminants Dec. 5 at the University of Lethbridge. The expert on pharmaceuticals in water will be working in Alberta starting in January as the Fulbright Research Chair on water and the environment.

Brooks said some river systems in the United States have reached the point where most of their flow below major cities is made up of reclaimed waste water discharge. 

An example is the Trinity River and the Livingston Reservoir, which supply the city of Houston, Texas. 

Brooks said Trinity stream flow has been rising in recent years despite a major drought and burgeoning population. It’s because of treated waste water.

“Water reuse experts call the Trinity River an unplanned water reuse project,” said Brooks. “The urban water cycle is the new normal,” so some systems are effluent dominant or effluent dependent for their flow.

Water treatment plants do not remove all contaminants, including the active ingredients in Prozac and other drugs ingested by humans that eventually end up in waste water. 

Brooks said most environmental protection goals regarding water are based on the idea of dilution. However, dilution does not occur if waste water is the primary source of flow.

Statistics on the number of effluent-dominated systems in the U.S. are not readily available, but Brooks said his research indicates more than 200 are not getting any dilution.

“The effective duration of exposure has been modified,” he said.

Whether the drugs are harmful or fatal to fish is the topic of considerable research involving contaminant persistence, bioaccumulation and toxicity.

Many human medications that end up in the water system are persistent, but few are inherently toxic.

“You don’t want to make a drug that kills you. You do want to make a drug that kills things in you,” he said.

The effects of pharmaceuticals on humans, including side effects, are widely studied, but far less is known about residual effects on aquatic species. Researchers have found that exposure to sertraline, the active ingredient in antidepressants, makes fathead minnows less attentive to nest protection. It is only one example of ongoing research. 

Brooks said people connect with the topic of water contamination from pharmaceuticals and their role within that, which may bode well for eventual solutions.


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