Pollutants change 'he' frogs into 'she' frogs

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http://news.yahoo.com/s/afp/20070227/sc_afp/scienceenvironmentanimalssexfrogs;_ylt=An02NIoZBrn1mf23OxZyAATMWM0F

Pollutants change 'he' frogs into 'she' frogs

by Marlowe Hood Tue Feb 27, 7:02 AM ET

PARIS (AFP) - 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.

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