University of California scientists say amphibians around the world are in danger from even extremely low concentrations of widely used pesticides.
The UC-Berkeley scientists say frogs exposed to a mix of pesticides at concentrations such as those found around farms suffer deadly infections, The Los Angeles Times reported Wednesday. And that, the researchers said, suggests the chemicals might be responsible, in part, for the global disappearance of amphibians.
When tadpoles were exposed in laboratory experiments to each pesticide individually, four percent died, the scientists told the Times. But when the herbicide atrazine was mixed with eight other chemicals to replicate a Nebraska cornfield, 35 percent died.
An international group of biologists said at least one-third of amphibians worldwide -- 1,856 known species of frogs, toads, salamanders and caecilians -- are in danger of extinction from a variety of factors such as climate change, parasites, chemicals and ultraviolet radiation.
"We demonstrated that a realistic pesticides mixture at low, ecologically relevant concentrations can have dramatic effects on amphibian development and growth and ultimately, we predict, survivorship," biology Professor Tyrone Hayes and colleagues reported in the online version of the journal Environmental Health Perspectives.
Copyright 2006 by United Press International
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