A medication commonly taken for Type II
diabetes, which is being found in freshwater systems worldwide, has been shown
to cause intersex in fish –male fish that produce eggs, according to Newswise.
A study by Rebecca Klaper at the University
of Wisconsin-Milwaukee determined exposure to the diabetes medicine metformin
causes physical changes in male fish exposed to doses similar to the amount in
wastewater effluent.
In addition to intersex conditions, fish
exposed to metformin were smaller in size than those not exposed, said Klaper,
a professor in UWM’s School of Freshwater Sciences.
The study, co-authored by Nicholas Niemuth,
a researcher in Klaper’s lab, was recently published in the journal
Chemosphere.
Photo: Sarah G |
Initially, the results of her study seemed
surprising since metformin is not a hormone and it targets blood sugar
regulation.
But Klaper said it is also prescribed to
women with a common hormonal disease called polycystic ovary syndrome. The
research in her lab indicates metformin could be a potential endocrine
disruptor – a chemical that confuses the body’s complicated hormonal messaging
system, interrupting a range of normal activities, including reproduction.
Of the chemicals she has detected in water samples
collected from Lake Michigan, metformin stands out, Klaper said.
“It is the chemical we found in almost
every sample and in the highest concentrations compared to other emerging
contaminants – even higher than caffeine,” she said.
The prevalence of the chemical in samples
led Klaper to investigate what effects the medication may have in the
environment. In a previous study, she exposed mature fish to metformin, and
although there were no physical changes, she found the genes related to
hormones for egg production were being expressed in males as well as females –
an indication of endocrine disruption.
For the current study, the researchers
monitored fish that had continuous exposure to metformin from birth to
adulthood. The next step is to determine the corresponding changes in the
genome, which Klaper is doing at UWM’s Great Lakes Genomic Center.
“We’re now working on a paper that
investigates the metabolic pathways at various points in the fishes’ life to
see what is changing with exposure,” she says.
Visit the School of Freshwater Sciences site HERE.
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