Keith Matheny

Detroit Free Press

DETROIT — A new study might depress anyone concerned with Great Lakes water quality.

Antidepressant drugs, making their way through an increasing number of people's bodies, getting excreted in small amounts into their toilets, and moving through the wastewater treatment process to lakes and rivers, are being found in multiple Great Lakes fish species' brains, new research by the University of Buffalo has found.

Researchers detected high concentrations of both the active ingredients and metabolites — byproducts of the parent drug — of popular antidepressant pharmaceuticals including Zoloft, Prozac, Celexa and Sarafem in the brains of fish caught in the Niagara River connecting Lake Erie and Lake Ontario.

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Affected species included smallmouth and largemouth bass, rudd, rock bass, white bass, white and yellow perch, walleye, bowfin and steelhead. While the concentrations aren't potentially harmful to humans eating the fish, they are problematic, said University of Buffalo chemistry professor Diana Aga, the lead author of the study published Aug. 16 in the journal Environmental Science and Technology.

"It is a threat to biodiversity, and we should be very concerned," she said.

Previous research has shown antidepressants in water create "suicidal shrimp" that swim toward light instead of away from it, making them vulnerable to predator fish and birds, Aga said.

"Other research teams have shown that antidepressants can affect the feeding behavior of fish, or their survival instincts," Aga said. "Some fish won't acknowledge the presence of predators as much."

That has the potential to affect delicate ecological balances in the Great Lakes, already under siege from invasive species. Ultimately, it could disrupt the sport fishing that fuels a multibillion-dollar industry in Michigan.

Prior to her research, Aga expected that higher concentrations of the drugs would be found in larger fish, predators higher in the food web, due to bioaccumulation, a process by which big fish, eating medium-sized fish, that eat smaller fish, amplifies the concentration of contaminants each step of the way.

But that wasn't the case with the fish studied, "which means they are not getting it by eating smaller fish; they're getting it from being in the water," she said.

Sertraline, the active ingredient in Zoloft, was found at levels estimated 20 times higher than levels in Niagara River water. And levels of norsertraline, the drug's breakdown product, were even greater, reaching concentrations often hundreds of times higher than that found in the river. That means the drugs appear to be accumulating in the fish over their prolonged exposures to them, Aga said.

Concern for pharmaceutical contamination of lakes and rivers has risen with the emerging technological ability to detect the drugs in very small quantities in water bodies — and as use of the prescription drugs has exploded.

The percentage of Americans taking antidepressants rose 65% between 2002 and 2014, according to the National Center for Health Statistics. From 2011 to 2014, some 12.7% of Americans age 12 or older had taken antidepressant medication within the past month.

Most wastewater treatment plants don't screen for such drugs, only screening for waste solids and treating to kill E. coli bacteria.

"These plants are focused on removing nitrogen, phosphorus and dissolved organic carbon, but there are so many other chemicals that are not prioritized that impact our environment," Aga said. "As a result, wildlife are exposed to all of these chemicals.

"Fish are receiving this cocktail of drugs 24 hours a day, and we are now finding these drugs in their brains."

Aga said she will be partnering with fish biologists to look at the minimum levels at which exposures to antidepressants affect fish behavior and biology.

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