The Popular Pesticide That Makes Frogs Hermaphrodites

“I am not now / That which I have been.” —Lord Byron, Childe Harold’s Pilgrimage

In A Nutshell

Atrazine is the second–most popular pesticide in the United States, widely used on crops such as corn, sorghum, and sugarcane to combat weeds. But Atrazine has been banned in the European Union since 2004. Why? It’s known to have a significant effect on wildlife, such as frogs—who may spontaneously change sex. The EPA continues to conduct research on Atrazine’s effects on humans.

The Whole Bushel

Weeds are surefire crop destroyers. What’s a convenient way to combat weeds? Herbicides. But some herbicides may do more damage than they’re worth.

Atrazine is the second–most popular pesticide in the United States. Atrazine is effective at killing existing weeds and preventing new ones from growing. It’s most widely used on corn, which is immune to its effects, and can be broken down by microorganisms (very slowly). Atrazine is relatively cheap, and can cause around a 6 percent greater yield in crop harvesting.

As a result, Atrazine became one of the most extensively used pesticides in the world. But Atrazine, it turns out, is an endocrine disrupter. In other words, it can cause birth and developmental defects as well as cancer.

Atrazine’s effects were well illustrated in frog populations. Thanks to contaminated water, male frogs would spontaneously become hermaphrodites and even give birth. Some frogs had multiple testes or ovaries. Other frogs were left with debilitating infections. Atrazine also had similar effects on fish.

Worse still, 75 percent of stream water and 40 percent of groundwater near US agricultural areas has been contaminated. Frogs just can’t catch a break—and neither can the humans who use that water for drinking. Atrazine was found in 80 percent of 153 surveyed public water systems.

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It doesn’t take much for Atrazine to have an effect. Frogs have suffered through a puberty nightmare thanks to concentrations as low as 0.1 micrograms per liter.

In 2004, the European Union banned Atrazine, but it remains widely used in the United States. While the Environmental Protection Agency has been researching Atrazine for over a decade, they have yet to produce a definitive conclusion on the pesticide’s effect on humans. Studies, however, have linked Atrazine to birth defects, menstrual problems, and greater susceptibility to cancer.

It is important to note that while frogs exposed to Atrazine didn’t intend to become hermaphrodites, certain frog species, such as Rana rugosa, actually have been known to actively change their sex in a gender-barren environment.

Show Me The Proof

Natural Resources Defense Council: Atrazine: Poisoning the Well
Northwest Center for Alternatives to Pesticides: Atrazine and Frogs
US Environmental Protection Agency: Atrazine Updates
EPA considers ban on herbicide that triggers sex reversal in frogs
Genetics Society of America: Change of the Heterogametic Sex From Male to Female in the Frog

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