Antidepressants found accumulating in fish brains

Washington: Human antidepressants are building up in the brains of common fish in the Great Lakes region in the US, scientists say.

In a new study, researchers detected high concentrations of these drugs and their metabolised remnants in the brain tissue of 10 fish species found in the Niagara River.

This vital conduit connects two of the Great Lakes, Lake Erie and Lake Ontario, via Niagara Falls.

The discovery of antidepressants in aquatic life in the river raises serious environmental concerns, said Diana Aga, from the University at Buffalo in the US.

"These active ingredients from antidepressants, which are coming out from wastewater treatment plants, are accumulating in fish brains," Aga said.

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

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

If changes like these occur in the wild, they have the potential to disrupt the delicate balance between species that helps to keep the ecosystem stable, said Randolph Singh, a recent graduate from Aga's lab.

"The levels of antidepressants found do not pose a danger to humans who eat the fish, especially in the US, where most people do not eat organs like the brain," Singh said.

"However, the risk that the drugs pose to biodiversity is real, and scientists are just beginning to understand what the consequences might be," he said.

The study looked for a variety of pharmaceutical and personal care product chemicals in the organs and muscles of 10 fish species: smallmouth bass, largemouth bass, rudd, rock bass, white bass, white perch, walleye, bowfin, steelhead and yellow perch.

Antidepressants stood out as a major problem. These drugs or their metabolites were found in the brains of every fish species the scientists studied.

The highest concentration of a single compound was found in a rock bass, which had about 400 nanogrammes of norsertraline - a metabolite of sertraline, the active ingredient in Zoloft - per gramme of brain tissue.

This was in addition to a cocktail of other compounds found in the same fish, including citalopram, the active ingredient in Celexa, and norfluoxetine, a metabolite of the active ingredient in Prozac and Sarafem.

More than half of the fish brain samples had norsertraline levels of 100 nanogrammes per gramme or higher.

In addition, like the rock bass, many of the fish had a medley of antidepressant drugs and metabolites in their brains.