[Pharmwaste] POLLUTANTS CHANGE 'HE' FROGS INTO 'SHE' FROGS

[DeBiasi,Deborah]

http://www.precaution.org/lib/07/prn_sex-changed_frogs.070227.htm

Agence France Presse, February 27, 2007

POLLUTANTS CHANGE 'HE' FROGS INTO 'SHE' FROGS

[Rachel's introduction: "Even tadpoles exposed to the weakest
concentration of the hormone were, in one of two groups, twice as likely
to become females.... The population of the two groups receiving the
heaviest dose of estrogen became 95 percent female in one case, and 100
percent in the other."]

By Marlowe Hood

Frogs that started life as male tadpoles were changed in an experiment
into females by estrogen-like pollutants similar to those found in the
environment, according to a new study.

The results may shed light on at least one reason that up to a third of
frog species around the world are threatened with extinction, suggests
the study, set to appear in the journal Environmental Toxicology and
Chemistry in May.

In a laboratory at Uppsala University in Sweden, two species of frogs
were exposed to levels of estrogen similar to those detected in natural
bodies of water in Europe, the United States and Canada.

The results were startling: whereas the percentage of females in two
control groups was under 50 percent -- not unusual among frogs -- the
sex ratio in three pairs of groups maturing in water dosed with
different levels of estrogen were significantly skewed.

Even tadpoles exposed to the weakest concentration of the hormone were,
in one of two groups, twice as likely to become females.

The population of the two groups receiving the heaviest dose of estrogen
became 95 percent female in one case, and 100 percent in the other.

"The results are quite alarming," said co-author Cecilia Berg, a
research in environmental toxicology. "We see these dramatic changes by
exposing the frogs to a single substance. In nature there could be lots
of other compounds acting together."

Earlier studies in the United States, Berg explained, linked a similar
sex-reversal of Rana pipiens male frogs -- one of the two species used
in the experiment -- in the wild to a pesticide that produced
estrogen-like compounds.

"Pesticides and other industrial chemicals have the ability to act like
estrogen in the body," Berg said. "That is what inspired us to do the
experiment," she said referring to her collaborator and lead author of
the article, Irina Pettersson, also a researcher at Uppsala.

The other species examined was the European common frog, Rana
temporaria.

Some of sex-altered males became fully functioning females, but other
had ovaries but no oviducts, making them sterile, Berg explained.

The study does not measure the potential impact of pollutant-driven sex
change for frog species, but the implications, said Berg, are
disquieting.

"Obviously if all the frogs become female it could have a detrimental
effect on the population," she said.

The only immediate remedy, she continued, would be to improve sewage
treatment in areas where frogs and other amphibians might be affected to
filter out estrogen concentrations coming from contraceptive pills and
from industrial pollutants.



Deborah L. DeBiasi
Email:   dldebiasi at deq.virginia.gov
WEB site address:  www.deq.virginia.gov
Virginia Department of Environmental Quality
Office of Water Permit Programs
Industrial Pretreatment/Toxics Management Program
Mail:          P.O. Box 1105, Richmond, VA  23218 (NEW!)
Location:  629 E. Main Street, Richmond, VA  23219
PH:         804-698-4028
FAX:      804-698-4032