Antidepressants turning up in Great Lakes fish
DULUTH — Human antidepressant drugs are showing up in the brains of fish in the Great Lakes region, an unexpected byproduct of human waste that isn't being removed in the sewage treatment process.
The University at Buffalo in New York reported Thursday, Aug. 31, that "high concentrations" of antidepressants are building up in the brains of trout, walleye, bass and several other fish sampled from the Niagara River between lakes Erie and Ontario, the downstream end of the Great Lakes system.
The drugs were found in all 10 species studied, said Diana Aga, lead scientists on the study who said the discovery raises "serious environmental concerns."
"These active ingredients from antidepressants, which are coming out from wastewater treatment plants, are accumulating in fish brains," Aga says. "It is a threat to biodiversity, and we should be very concerned."
The study was published in the most recent issue of the journal Environmental Science and Technology.
It's the first study to find antidepressants in Great Lakes region fish and the first to find them in so many different species of fish. But the results are similar to a 2010 study that found antidepressants in fish downstream of sewage treatment plants, but not upstream, in small streams in Iowa and Colorado.
Aga said the drugs "could affect fish behavior. We didn't look at behavior in our study, but other research teams (in laboratory tests) 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."
If that also occurred in the wild, the changes have the potential to disrupt the delicate balance between species that helps to keep the ecosystem stable, said Randolph Singh, study co-author.
Singh said the amount of antidepressants in fish brains doesn't pose a threat to people who eat fish, especially since most people don't eat fish brains.
But "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 research team included other scientists from the University at Buffalo, Ramkhamhaeng University and Khon Kaen University, both in Thailand, and SUNY Buffalo State.
The study echoes others in recent decades that found endocrine disrupters in fish that in some cases made male fish to develop female body parts. Those endocrine disrupters came from chemicals in drugs that pass through people's urine and also through sewage plants.
Wastewater treatment facilities simply weren't designed to remove such chemicals. Their processes generally focus on killing disease-causing bacteria and on extracting solid matter such as human excrement and removing nitrogen, phosphorus and dissolved organic carbon, not man-made chemicals that are passed through human urine. (The fact wastewater plants don't remove most drugs is also the reason officials ask that people not flush unwanted prescription or other drugs down the drain.)
Aga has focused her research on detecting contaminants such as pharmaceuticals, antibiotics and endocrine disrupters in the environment and says they present a growing problem. She noted that the percentage of Americans taking antidepressants, for instance, rose 65 percent between 1999 and 2014, according to the National Center for Health Statistics.
The new 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.
The study also appears to show that the drugs are bioaccumulating in the fish — that they are building up over time — because the levels in the fish brains were higher than the levels found in the water where they lived; in some cases 20 times higher.
The highest concentration of a single compound was found in a rock bass, which had about 400 nanograms of norsertraline — a metabolite of sertraline, the active ingredient in Zoloft — per gram 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.
Evidence that antidepressants can change fish behavior generally comes from laboratory studies that expose the animals to higher concentrations of drugs than what is found in the Niagara River. Scientists have not done enough research yet to understand what amount of antidepressants poses a risk to animals, or how multiple drugs might interact synergistically to influence behavior, Aga said.