Popular herbicide affects sexual development in frogs, research finds

There have been numerous scientific and journalistic reports on the detrimental effects of herbicides, including atrazine, yet investigations by other research teams report no adverse effects of the popular herbicide.

In an attempt to help resolve differences between the various reports, Dr. Vance Trudeau and his team at the University of Ottawa's Centre for Advanced Research in Environmental Genomics developed a system to evaluate the effects of a commercial formulation of atrazine. Specifically, PhD student Valérie Langlois applied it to outdoor tanks where tadpoles of leopard frogs were kept for an entire spring and summer. Under these semi-natural conditions in mesocosms, the levels of atrazine were low and comparable to those measured in the Canadian environment.

At the end of the summer, the results showed that atrazine levels in the tanks were at levels within currently acceptable guidelines. However, researchers also found that the herbicide reduced the number of tadpoles reaching the froglet stage. Also noteworthy was that atrazine had a feminizing effect on the animal, resulting in sex ratios favouring females, with a reduced number of males.

This study, recently available online in the journal Environmental Health Perspectives, raises important questions about the level of atrazine in the environment, and its negative effects on animal development.

Atrazine is one of the top selling herbicides used worldwide and was designed to inhibit weed growth in cornfields. It is so widely used that it can be detected in many rivers, streams and in some water supplies. This has raised the alarm on the possibility of other serious detrimental environmental effects.