07 December 2009


Atrazine is a herbicide widely used on crop fields around the World to control broadleaf and grassy weeds. The negative effects that this commonly used agro-chemical pesticide have on frogs received high scientific and general public attention in 2002. Nonetheless, a previous study by Diana et al. (2000) had already highlighted that high concentrations of Atrazine in artificial aquatic communities resulted in frogs with a decrease in length and weight at metamorphosis, which may result in fitness reduction.

The studies by Tyrone Hayes and colleagues at the University of California, Berkeley, USA, in 2002, demonstrated that exposure of frogs to low levels of Atrazine induced abnormalities such as retarded development and hermaphroditism. The findings of impaired reproductive function suggested that natural frog populations exposed to this herbicide may suffer declines.  However, investigations by other research teams, including Syngenta, the principal Atrazine registrant, reported no adverse effects.

The U.S. Environmental Protection Agency (EPA), based on a review of laboratory and field studies, concluded (2007) that Atrazine does not adversely affect amphibian gonadal development. Beginning this fall (2009), EPA started a comprehensive reevaluation of Atrazine’s ecological effects, including potential effects on amphibians and human health.

Atrazine was recently shown by Suzawa and Ingraham (2008) to potentially disrupt normal endocrine development and function in lower and higher vertebrates. And this month (2009), it was released a study performed by researchers at the University of Otawa, Canada, which found that Atrazine alters the sexual development and had a feminizing effect on studied frogs, resulting in sex ratios favoring females, with a reduced number of males. The issue is back!

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