Environmental Health Perspectives (EHP) is a monthly journal of peer-reviewed research and news on the impact of the environment on human health. EHP is published by the National Institute of Environmental Health Sciences and its content is free online. Print issues are available by paid subscription.DISCLAIMER
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23 October 2002
New Study Finds Very Low Levels of Exposure to Common Herbicide
Causes Sex Reversal, Hermaphroditism in Frogs
Study Published Today in Environmental Health Perspectives Finds
Impact of Atrazine Exposure the Same in Lab, Field Tests
[RESEARCH TRIANGLE PARK, NC] A new study published today in the science
journal Environmental Health Perspectives found that even very low-level
exposure to atrazine, the most commonly used herbicide in the United
States, altered reproductive organs in developing male leopard frogs.
The study comes at a time when the effects of atrazine on environmental
health are undergoing scientific review by the U.S. Environmental
Protection Agency. Today’s study compared results for frogs exposed
in the lab with those for some 800 frogs found in locations from Utah
to the Iowa-Illinois border.
Observations in both the lab frogs and the wild frogs were the same:
exposure at concentrations as low as 0.1 part per billion (ppb) resulted
in retarded gonadal development, the presence of female reproductive
cells in male testes (hermaphroditism), and even complete sex reversal.
This exposure concentration is 30 times lower than the current drinking
water standard of 3 ppb.
The study authors found that 36% of the males exposed to 0.1 ppb atrazine
had underdeveloped testes. Further, 29% of the animals exposed at
this level displayed varying degrees of sex reversal. Some males appeared
to undergo complete sex reversal and had gonads almost completely
filled with immature female egg cells. At one field site, on the North
Platte River in Wyoming, 92% of the males observed had testicular
oocytes, and many of the animals showed advanced stages of complete
sex reversal. There were no observable effects in atrazine-treated
females.
The study team was headed by Tyrone B. Hayes of the Laboratory for
Integrative Studies in Amphibian Biology and the University of California-Berkeley.
Other authors include Kelly Haston, Mable Tsui, Anhthu Hoang, Cathryn
Haeffele, and Aaron Vonk.
EHP is the journal of the National Institute of Environmental Health
Sciences, one of the National Institutes of Health in the U.S. Department
of Health and Human Services. More information is available online
at http://www.ehponline.org.
