Researchers in the United States say they have turned male frogs into females by exposing the amphibians to tiny amounts of atrazine, a weed killer widely used on corn fields in Canada and often found in water supplies in agricultural areas.
The chemically induced sex change occurred by dosing frogs at concentrations of the herbicide 50 per cent below Health Canada's guideline for drinking water.
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The discovery that in an experimental setting atrazine induces sex changes in frogs is likely to further increase the controversy over the chemical, which has been banned in Europe because it contaminates ground water but is one of the most commonly used herbicides in North America.
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All the atrazine sold in Canada is made by Syngenta AG, a Swiss-based seed and pesticide producer that has previously disputed findings that the herbicide hazardous. ...Atrazine has been dogged by controversy since the late 1980s, when it was found to cause mammary tumours in one strain of laboratory rats...
A part per billion is an extremely small amount, the equivalent of one second or elapsed time over a 32-year period. The experimental dose used was below Canada's drinking water guideline of 5 ppb, but above the safe wildlife exposure standard of 1.8 ppb. Figures contained in Health Canada's 2007 atrazine evaluation found concentrations in groundwater of up to 1.2 ppb.
