Traces of anxiety drug may affect behavior in fish

Desdemona Despair

By PAM BELLUCK
14 February 2013

(The New York Times) – Traces of a common psychiatric medication that winds up in rivers and streams may affect fish behavior and feeding patterns, according to a study in the journal Science published Thursday.

Researchers in Sweden exposed wild European perch to water with different concentrations of Oxazepam, an anti-anxiety medication that can show up in waterways after being flushed, excreted or discarded.

Researchers reported that fish exposed to Oxazepam became less social, more active and ate faster, behaviors they said could have long-term consequences for aquatic ecosystems.

Scientists who study pharmaceuticals in waterways said the research was intriguing because it examined the potential effect on animals of a specific medication intended to affect human behavior.

“It seems to be a solid study with an environmentally relevant species,” said Donald Tillitt, an environmental toxicologist with the United States Geological Survey, who was not involved in the study. He said it made sense that a medication that binds with a certain brain receptor in people could act similarly in fish, and the measures of behavior — activity, sociability, boldness and feeding rate — “are all important ones that we like to look at when we’re trying to see the environmental effects of pharmaceuticals.”

Still, because even the lowest concentration of Oxazepam in the study was higher than that found in a Swedish waterway that researchers tested, “the relevance of their study to the real world is unclear,” the United States Environmental Protection Agency said in written answers to questions.

The agency said that while “most pharmaceuticals do not seem to pose known risks to humans, animals or the rest of the ecosystem” at the levels they occur in the environment, there are some medications “for which some researchers have noted physiological effects in fish exposed to levels close to those occasionally reached in the environment. These include some ingredients used for contraception, hypertension, and mood disorders.”

The agency said how often this occurs and the possible environmental repercussions are unknown. […]

The United States Geological Survey has found “intersex fish,” or male fish that develop female sexual characteristics, in the Potomac River and its tributaries, raising questions about whether hormone residues might be responsible. A study in the journal Environmental Science and Technology found antidepressants like Prozac and Zoloft in the brains of fish collected downstream from wastewater discharge in Colorado and Iowa. But some antidepressants that were more common in those waterways, including Zyban and Citalopram, were not found as frequently in the fish. [more]

Traces of Anxiety Drug May Affect Behavior in Fish

ABSTRACT: Environmental pollution by pharmaceuticals is increasingly recognized as a major threat to aquatic ecosystems worldwide. A variety of pharmaceuticals enter waterways by way of treated wastewater effluents and remain biochemically active in aquatic systems. Several ecotoxicological studies have been done, but generally, little is known about the ecological effects of pharmaceuticals. Here we show that a benzodiazepine anxiolytic drug (oxazepam) alters behavior and feeding rate of wild European perch (Perca fluviatilis) at concentrations encountered in effluent-influenced surface waters. Individuals exposed to water with dilute drug concentrations (1.8 micrograms liter–1) exhibited increased activity, reduced sociality, and higher feeding rate. As such, our results show that anxiolytic drugs in surface waters alter animal behaviors that are known to have ecological and evolutionary consequences.

Dilute Concentrations of a Psychiatric Drug Alter Behavior of Fish from Natural Populations