[Pharmwaste] article: pollutants make male frogs female

[Tenace, Laurie]

Old news for us, but I find it interesting that this article is from the
Shanghai Daily - Laurie

http://english.eastday.com/eastday/englishedition/features/userobject1ai26533
56.html

Study: pollutants make male frogs female 
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1/3/2007 10:15 


One reason up to a third of the world's frog species are in danger of
extinction may be estrogen-like pollutants in the environment that turn male
tadpoles into females, according to a new study. 

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

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 researcher
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." 

The results revealed 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. 

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.


Laurie J. Tenace
Environmental Specialist
Florida Department of Environmental Protection
2600 Blair Stone Road, MS 4555
Tallahassee, Florida 32399-2400
PH: (850) 245-8759
FAX: (850) 245-8811
Laurie.Tenace at dep.state.fl.us 

view our mercury web pages at:
http://www.dep.state.fl.us/waste/categories/mercury/default.htm

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