Antidepressants now also in fish

Residual substances in rivers accumulate in the brain tissue of perch and co

Residues of antidepressants apparently accumulate in river dwellers like this stone perch. © public domain
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Involuntary psychopharmaceutical therapy: The water of rivers and lakes is now also burdened with residues of antidepressants - and these accumulate in fish, as a US study shows. At rehearsals in the Niagara River, all fish had elevated levels of drugs in the brain. The researchers fear that the antidepressants could alter fish behavior and threaten biodiversity.

Whether antibiotics, contraceptives or psychotropic drugs: With our wastewater more and more drug residues in rivers and lakes, because the treatment plants can not completely remove these drugs. For the animals living there, this is not without consequences. For example, in fish-impregnated waters, native fish change behavior or male frogs and toads undergo involuntary sex changes.

Diana Aga from the University at Buffalo and her colleagues have now studied how sustainable the contact with such substances is on fish and co. The researchers wanted to know: How strongly do certain drug residues accumulate in the body of the animals? To find out, they studied fish living in the Niagara River in North America, analyzing tissues and muscles from a total of ten different species.

Active ingredient cocktail in the brain

The analysis revealed a particular class of psychotropic drugs: antidepressants. These agents or degradation products thereof were detected by the scientists in each of the fish species studied. The highest concentration of a single drug they found in the brain of a stone perch.

400 grams of norsertraline, a breakdown product of the antidepressant sertraline from the group of serotonin reuptake inhibitors, had accumulated there per gram of tissue. In addition, the same fish had a cocktail of other substances in his brain - including drugs such as citalopram and norfluoxetine. display

Changed behavior?

So the perch was not an isolated case, as Aga and her colleagues report. According to this, many fish, in addition to residues of norsertralin, had a true cocktail of other substances used as anti-depressants in their brains. "The accumulation of these constituents in the animal's brain tissue is highly alarming and may pose a threat to biodiversity in the affected ecosystems, " says Aga.

The researchers feared that the psychotropic drugs could affect the behavior of the fish. "We did not check that in our study. However, other studies show that such substances can, for example, have a negative effect on the feeding behavior or the survival instincts of fish, "states the team.

Continuous load as a problem

Particularly problematic here: If the fish are exposed to the drugs over a longer period, accumulate more and more residues in the body of the animals. The analyzes showed that tissue concentrations in tissue often exceed those measured in water significantly. In the brains of rockfish, smallmouth bass and largemouth bass, for example, the sertraline content was on average at least twenty times higher than in river water itself.

How this ever-increasing burden on the animals in the long run and what influence a cocktail of different substances have had been researched so far, the researchers said. "These residues are a real risk to biodiversity, but researchers are just beginning to understand the implications of this, " says Aga's colleague Randolph Singh.

The problem will probably increase in the future rather than subside, the researchers feared. Already in recent years, the number of prescriptions for antidepressants has risen - a trend that can continue in the future and increasingly burden the fish in our rivers and lakes. (Environmental Science & Technology, 2017; doi: 10.1021 / acs.est.7b02912)

(University at Buffalo, 04.09.2017 - DAL)