Widely Used Weedkiller Turns Male Frogs Into Females

Atrazine, one of the most widely-used weedkillers, can turn male frogs into females, researchers reported on Monday. “Atrazine-exposed males were both demasculinized (chemically castrated) and completely feminized as adults,” Tyrone Hayes of the University of California Berkeley and colleagues wrote in the Proceedings of the National Academy of Sciences. The atrazine can turn male frogs into females that are able to mate and successfully reproduce.

Previously the chemical had been shown to disrupt development and create hermaphroditism in frogs, whereby they develop both male and female features. This latest study of 40 male frogs shows the process can go even further, Hayes said. “Atrazine has caused a hormonal imbalance that has made them develop into the wrong sex, in terms of their genetic constitution.”

Although banned in the European Union in 2004, atrazine is still one of the most commonly used herbicides across the globe. Its endocrine disruptor effects, possible carcinogenic effect, and epidemiological connection to low sperm levels in men has led several researchers to call for banning it in the US. Like many herbicides, it is sold under numerous trade names (see next page).

“Approximately 80 million pounds are applied annually in the United States alone, and atrazine is the most common pesticide contaminant of ground and surface water,” the researchers wrote. It can be transported more than 621 miles from the point of application via rainfall and, as a result, contaminates otherwise pristine habitats, even in remote areas where it is not used.

I’m not all that surprised to hear that Syngenta AG, one of several companies that makes atrazine, has long defended its safety. The company says it is one of the best-studied herbicides available and pointed to prior safety reviews from the EPA and World Health Organization, among others.

Next: Trade names for atrazine

Photo: Tyrone B. Hayes, the University of California, Berkeley

From the Consumer Fact Sheet on atrazine published by the EPA, this list of trade names may help you find out whether you are using this chemical at home or work:

Actinite PK
Weedex A

With atrazine’s prevalence in our water system, you should know that, according to NRDC, some large water systems test for atrazine in their water supplies and filter it from drinking water if necessary, but smaller systems often do not. The good news is that a simple activated carbon-based water filter–like the ones commonly available in grocery stores and elsewhere in pitcher and faucet-mount varieties–can filter atrazine from drinking water.


W. C
W. C6 months ago


William C
William C6 months ago

Thank you for the information.

Ahmed G.
Ahmed G.6 years ago

I always tell my students to get acquainted with allelopathy ( see my previous comments of 2010). Plant extracts will be the future to replace pesticides. I am conducting some short experiments to compare the efficacy of herbicides and Eucalyptus leaf extracts.I encourage Weed Scientists to shift their interests to allelopathy. Natural compounds ( plant- made chemicals) are friends to the environment and are bad enemies to pests.

Ahmed G.
Ahmed G.6 years ago

Yes Loesje, you can go back to nature, and use organic agriculture to produce your apples and potatoes.The problem is organic agric. is very limited, and thanks for the chemicals, which are produced by the wise guys. We know for sure we "pump" hundreds of thousands of pesticides to kill pests, which include rats, roaches, and weeds, but not "frogies"!! Well, herbicides ( atrazine is one of them) are useful when applied carefully.Weeds are controlled by atrazine and others to harvest high yield of wheat, onions, eggplants, and cherry, and some other goodies, which we would like to see in our birthday cakes.Should we put the blame on atrazine, or should it be on our "eager" farmers? When we spray atrazine, we have to be sure that this chemical does not contaminate the wilderness. Unfortunately, some farmers, however, may " play a rough game" and the redult is the escape of few drops of atrazine from the sprayed area to the neighbors territory, which happen to be a territory of male frogies.

Loesje vB
Loesje Najoan6 years ago

Can we live without chemicals or pesticides? If the ground and water are being contaminant and the atrazine can turn male frogs into females and how about for the humans?
This is weird and please go back to the nature.

K s Goh
KS Goh6 years ago

Thanks for the article.

Masha Samoilova
Past Member 6 years ago

thanks, we have to question the amount of fertilizer we use

Bea W.
Bea W.6 years ago

Wow, if this chemical changes male frogs into female frogs, does it mean we might have a shortage of baby frogs?

David N.
David N7 years ago

Thanks for the article. Very interesting!

Ahmed G.
Ahmed G.7 years ago

How bad is our judgment against atrazine? As agriculturists, we love atrazine for its high efficacy against weeds in corn fields and some other crops. Then again, we love and perhaps adore fogys, whether they were males of females. They provide colorful life around the ponds and streams of fresh water. They also make a pleasant "crocking" !!!! Nevertheless, let us stop for a minute and think scientifically. Does really sex transformation occur whenever a male frog gets exposed to atrazine? To answer this question, one should change his career and his profession and become a toxicologist. Well, I am not a toxi, but sure like to conduct an experiment with good statistical lay out using 1000 male frogs as experimental units and dose them with different conc. of atrazine. Watch and score the results. What is the probability of converting all males or half of them to females. I also like to set up the same test on females. They may turn out males ( reversed mechanism ) !! If this would happen, then we are in a state of equilibrium!!!!!!!.