-- Mary Elizabeth Dallas
FRIDAY, Feb. 15 (HealthDay News) -- Small amounts of
mood-altering drugs used to treat psychiatric disorders that are
making their way into rivers and streams may be changing the
behavior of some fish, a new study suggests.
Researchers in Sweden found exposure to the anti-anxiety drug,
Oxazepam, caused fish to become bolder, less social and eat
Reporting in the Feb. 15 issue of
Science, the researchers explained that trace amounts of the
drug and other medications end up in waterways downstream of
wastewater treatment plants, after being excreted by people. The
team worries that exposure of wildlife to pharmaceuticals such as
Oxazepam could eventually lead to unexpected ecological and
In the study, the researchers gave wild European perch a dose of
Oxazepam that was similar to the amounts of the drug found in
Sweden's waterways. They found that even trace amounts of the
mood-altering medication seemed to alter the behavior and foraging
rate of the wild perch.
"Normally, perch are shy and hunt in schools. This is a known strategy for survival and growth. But those who swim in Oxazepam became considerably bolder," lead researcher Tomas Brodin, an ecologist at Umea University, said in a university news release.
He said that perch exposed to Oxazepam became more independent,
leaving the safety of schools to forage on their own - potentially
exposing themselves to being eaten by other fish.
"In contrast, unexposed fish stayed hidden in their refuge," Brodin said in a news release from Science.
Since the fish also ate their food more quickly, the researchers
pointed out, this behavior could change the composition of species
in the water. This unbalance, they added, could alter ecological
events over time, such as the blooming of algae.
Exposure to Oxazepam also made the fish less social, making them
easier prey for potential predators, the researchers noted. "Perch
that were exposed to Oxazepam lost interest in hanging out with the
group, and some even stayed as far away from the group as
possible," said Brodin.
The study's authors suggested the wild fish in Sweden rivers and
streams may be experiencing similar changes since the
concentrations of the drug found in their muscles are similar to
the drug concentration in the fish examined in the study. They
noted wild fish are exposed to other drugs in waterways as well,
which could compound the effects on their behavior and the
The researchers said more studies are needed to investigate the
effects of drugs on wildlife and ecosystems.
"The solution to this problem isn't to stop medicating people who are ill but to try to develop sewage treatment plants that can capture environmentally hazardous drugs," study co-author Jerker Fick, also of Umea University, said in a university news release.
Find out more about psychiatric medications at the
U.S. National Institute of Mental Health.
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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