The recent study by a U.C. Berkeley professor of integrative biology shows that one in 10 male frogs exposed to atrazine turned into a female.
Professor Tyrone Hayes says atrazine is also one of the most common contaminants in ground water.
Our drinking water only allows 3 parts per billion (ppb), and the frogs were exposed to less.
"The frogs are affected by levels as low as point 1 parts per billion and in the paper we have coming up as low as .01 parts per billion start to cause hormonal and molecular changes," says Hayes.
Hayes believes the herbicide is a factor in the global decline of amphibians. Atrazine has already been banned by the European Union.