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ANTIDEPRESSANTS DELAY FISH, FROG DEVELOPMENT
Date: 031103
From: http://www.ascribe.org/
AScribe Newswire, Oct. 31, 2003
Athens, Ga - Researchers at the University of Georgia have found that
low-level exposure to a common class of antidepressants found in
streams and ponds delays both development in fish and metamorphosis in
frogs.
The scientists are studying toxicity of a widely used group of
antidepressants called selective serotonin reuptake inhibitors
(SSRIs).
The study has important environmental implications because some of
these widely prescribed drugs, which include Prozac, Zoloft, Paxil and
Celexa, have been found in low concentrations in surface water,
particularly wastewater.
"While these compounds are not acutely toxic at concentrations
detected in the environment, our longer term studies indicate delayed
development (in fish) and delayed metamorphosis (in frogs)," said UGA
aquatic toxicologist Marsha Black who led the study.
The researchers found that low concentrations of fluoxetine (Prozac),
the most commonly prescribed SSRI, significantly slowed development in
Gambusia, or mosquitofish, which are often used to study toxicity on
aquatic organisms.
"We found that male sexual development slowed by two to four weeks,"
said Ted Henry, a UGA researcher who also worked on the project.
When the fish were around 80-85 days old, he said, the sexual
maturity of those exposed to low levels of fluoxetine was
significantly delayed. However, by the end of the study, when the fish
were 145 days old, the same fish had caught up developmentally with
the unexposed fish.
"We're scratching our heads right now as to exactly what this means,"
Black said. "But we know that in water, timing is everything.
Reproduction for some species is timed to coincide with algae blooms
for example. And possibly if sexual development is delayed, timing of
reproduction could be affected and you could see some population
impact."
For the next phase of the study, the researchers will more closely
examine the reproductive tissue of the fish affected by fluoxetine.
Are they able to reproduce? Is there a reduction in the number of
embryos? Or is there no ultimate effect? "These are some of the
questions we'd like to answer," Black said. "There are still a lot of
unanswered questions."
The researchers also found that metamorphosis in frogs exposed to low
levels of fluoxetine took longer than usual.
For frogs, particularly the land-based frogs of North America, such a
delay could be a matter of life and death, Black said, because frog
eggs are often laid in temporary water beds - ephemeral ponds and
wetlands that dry up.
"If the tadpoles have not developed and undergone metamorphosis by
the time the water has evaporated, they'll dessicate with the ponds,"
Black said.
The researchers strongly suspect that results implicate a disruption
of thyroid function and will carry out further research this spring to
confirm or deny their suspicions.
"We know that the thyroid levels peak with metamorphic climax, when
the legs and arms form and the tail resorbs" Black said. "We believe
that fluoxetine inhibits the thyroid so we're measuring the thyroid
hormone levels next."
The number of prescriptions for SSRIs has exploded since Prozac first
came on the market 15 years ago. SSRIs are most often prescribed for
depression, but are also used to treat anxiety, panic disorder,
obsessive compulsive disorder, eating disorders, and social phobia.
Because they are prescribed for chronic conditions, people take them
for months or years, increasing the likelihood of build-up in surface
water, Black said.
A recent study by Baylor toxicologist Bryan Brooks found traces of
fluoxetine in the tissue of bluegills in a Texas creek fed by
discharges from a wastewater treatment plant.
"Treated municipal drinking water should be fine, but
[pharmaceuticals like SSRIs] may not be filtered out of wastewater,"
Black said. "We should be putting a high priority on implementing
technologies that remove them and other pharmaceuticals from municipal
wastewater discharges."
The findings of the UGA study will be presented at the 24th Annual
Meeting of the Society of Environmental Toxicity and Chemistry next
month.
* * *
AScribe Newswire / http://www.ascribe.org / 510-653-9400
Date: 031103
From: http://www.ascribe.org/
AScribe Newswire, Oct. 31, 2003
Athens, Ga - Researchers at the University of Georgia have found that
low-level exposure to a common class of antidepressants found in
streams and ponds delays both development in fish and metamorphosis in
frogs.
The scientists are studying toxicity of a widely used group of
antidepressants called selective serotonin reuptake inhibitors
(SSRIs).
The study has important environmental implications because some of
these widely prescribed drugs, which include Prozac, Zoloft, Paxil and
Celexa, have been found in low concentrations in surface water,
particularly wastewater.
"While these compounds are not acutely toxic at concentrations
detected in the environment, our longer term studies indicate delayed
development (in fish) and delayed metamorphosis (in frogs)," said UGA
aquatic toxicologist Marsha Black who led the study.
The researchers found that low concentrations of fluoxetine (Prozac),
the most commonly prescribed SSRI, significantly slowed development in
Gambusia, or mosquitofish, which are often used to study toxicity on
aquatic organisms.
"We found that male sexual development slowed by two to four weeks,"
said Ted Henry, a UGA researcher who also worked on the project.
When the fish were around 80-85 days old, he said, the sexual
maturity of those exposed to low levels of fluoxetine was
significantly delayed. However, by the end of the study, when the fish
were 145 days old, the same fish had caught up developmentally with
the unexposed fish.
"We're scratching our heads right now as to exactly what this means,"
Black said. "But we know that in water, timing is everything.
Reproduction for some species is timed to coincide with algae blooms
for example. And possibly if sexual development is delayed, timing of
reproduction could be affected and you could see some population
impact."
For the next phase of the study, the researchers will more closely
examine the reproductive tissue of the fish affected by fluoxetine.
Are they able to reproduce? Is there a reduction in the number of
embryos? Or is there no ultimate effect? "These are some of the
questions we'd like to answer," Black said. "There are still a lot of
unanswered questions."
The researchers also found that metamorphosis in frogs exposed to low
levels of fluoxetine took longer than usual.
For frogs, particularly the land-based frogs of North America, such a
delay could be a matter of life and death, Black said, because frog
eggs are often laid in temporary water beds - ephemeral ponds and
wetlands that dry up.
"If the tadpoles have not developed and undergone metamorphosis by
the time the water has evaporated, they'll dessicate with the ponds,"
Black said.
The researchers strongly suspect that results implicate a disruption
of thyroid function and will carry out further research this spring to
confirm or deny their suspicions.
"We know that the thyroid levels peak with metamorphic climax, when
the legs and arms form and the tail resorbs" Black said. "We believe
that fluoxetine inhibits the thyroid so we're measuring the thyroid
hormone levels next."
The number of prescriptions for SSRIs has exploded since Prozac first
came on the market 15 years ago. SSRIs are most often prescribed for
depression, but are also used to treat anxiety, panic disorder,
obsessive compulsive disorder, eating disorders, and social phobia.
Because they are prescribed for chronic conditions, people take them
for months or years, increasing the likelihood of build-up in surface
water, Black said.
A recent study by Baylor toxicologist Bryan Brooks found traces of
fluoxetine in the tissue of bluegills in a Texas creek fed by
discharges from a wastewater treatment plant.
"Treated municipal drinking water should be fine, but
[pharmaceuticals like SSRIs] may not be filtered out of wastewater,"
Black said. "We should be putting a high priority on implementing
technologies that remove them and other pharmaceuticals from municipal
wastewater discharges."
The findings of the UGA study will be presented at the 24th Annual
Meeting of the Society of Environmental Toxicity and Chemistry next
month.
* * *
AScribe Newswire / http://www.ascribe.org / 510-653-9400