Prozac may have a new side effect. It changes the behavior of wild starlings.
When fluoxetine, or Prozac, enters wastewater treatment plants, invertebrates—such as worms—take in the chemicals from the drugs. Wild starlings, or
Studies have shown that wastewater plants don’t completely remove the active ingredients and metabolites of pharmaceuticals as they go through their purification process—in fact, many water treatments plants aren’t currently doing anything to eradicate them. The drugs get in the water a few different ways. Everyone excretes either the drugs or their metabolites as waste or sweat, which are then flushed down the toilet or washed down the drain in the shower. Many people also pour excess pills down the toilet despite advisories against this from the U.S. Food and Drug Administration.
Kate Arnold, of the University of York, investigated how wild starlings are affected by pharmaceutical-contaminated water. After capturing 24 wild starlings, she split them into two groups: a control group and an experimental group. Experimental group birds ingested wax worms that had been injected with doses of fluoxetine. Scientists determined the amount of fluoxetine to give the worms by looking at data on wastewater in England, scrutinizing outside research on fluoxetine-exposed worms, and analyzing the rate at which starlings consume worms daily. The control group ate normal wax worms.
The scientists found that the birds foraged differently if they had ingested fluoxetine. Instead of eating a big breakfast and dinner and eating for energy periodically, the Prozac birds skipped breakfast and snacked throughout the day. A bird that snacks throughout the day will quickly gain weight—so in the wild, starlings that ingest fluoxetine might too heavy to escape from predators, according to Dr. Arnold.
GrrlScientist, of The Guardian, explains further concerns:
Fluoxetine is not the only pharmaceutical, nor is it the only antidepressant, that is present in the environment at detectable levels. Further, this gallimaufry of environmental pharmaceuticals and their active metabolites interact with each other in unknown ways, potentially creating a dangerous brew that is more potent than any individual contaminant due to additive or synergistic interactions. These interactions could lead to powerful or detrimental effects in wildlife — and indeed, in humans, too.
In a separate study, scientists showed that endocrine-disrupting chemicals, like the ones in contraceptive pills, affected nestling wild starlings in that the birds’ immune systems weakened and the birds couldn’t grow as quickly.
As scientists continue to study how wildlife is affected by the presence of pharmaceuticals in wastewater, they might uncover more about how these behavioral changes affect starlings’ lives and the food chain as a whole.