Atrazine: Hermaphrodite Frogs, Water Contamination, and Maybe Cancer

Unless you’re a corn farmer or environmental activist, chances are you’ve never heard of atrazine. But you may have drank it, and maybe you’ve even heard Alex Jones talk about it – that it “turns frogs gay.”

Atrazine is the second most commonly used herbicide in the United States. First registered in 1958, atrazine is used on the majority of corn croplands in the United States to fight against broadleaf and grassy weeds–to the tune of 70 million pounds a year,and these 70 million pounds find their way into our environment, with atrazine being the most common herbicide in American surface water. 

From there, it finds its way into our drinking water. The Environmental Working Group, which compiles and studies data on tap water in the United States, found that atrazine is present in the drinking water of “nearly 30 million Americans in 28 states,” primarily in the Midwestern Corn Belt. Additionally, concentrations above the legal levels have been found in multiple cities along the Ohio River, including Louisville.

This presence has been disastrous for the American taxpayer. Syngenta, the Swiss company that manufactures Atrazine, settled a lawsuit in 2012 filed by cities and towns across the Midwest. Just 16 cities reported spending around $350M to filter atrazine out of their water. Syngenta agreed to hand over $105M.

This and another lawsuit against Syngenta prompted the release of internal documents pertaining to their manufacturing and research of atrazine. Among other things, these documents contained disturbing revelations on how the company had treated a particular researcher, Dr. Tyrone Hayes.

Hayes was first contacted by Syngenta shortly after becoming a professor in the biology department at UC Berkeley in the 1990s. Hayes estimates that donations from the company paid for up to ¼ of the biology research there at the time. After the Environmental Protection Agency began expressing concerns about atrazine’s health effects, Syngenta paid Hayes to research the chemical in frogs in 1998. 

Hayes began observing frogs that had been exposed atrazine, finding that when male frogs were raised in water with atrazine levels as low as 2.5 ppb (current regulations allow for 3 ppb in drinking water and 15 ppb in surface water) they experienced a range of effects. Ten percent of the frogs underwent full feminization. These genetic males developed as females, with some even producing eggs. Males that did not undergo complete feminization experienced lower levels of testosterone, decreased sperm production, detriments to other sex characteristics, and were much less likely to mate with females, often preferring to mate with other males.

Following these findings, Hayes claims, and documents from the lawsuits confirm, that Syngentia pressured him to fudge data and later launched an offense against him. After unsuccessfully pressuring him to manipulate data, Syngentia terminated their relationship with Hayes. They did not leave his life, however. Syngentia recruited teams of scientists to discredit his work. Hayes also reports that Syngenta had been monitoring his private emails, and that one employee made intimidating statements about his wife and daughter. 

Interestingly, the studies funded by Syngenta tended to find that atrazine posed much less of a health risk, than did independent ones, and Hayes reports that the scientists conducting them were difficult to collaborate or share data with.  

While this was going on, the European Union banned the use of atrazine in 2003 over concerns of its “ubiquitous and unpreventable water contamination.” The U.S., on the other hand, allowed for its continued use, having set the limit for drinking water at 3 ppb in 1991. The 2003 decision to permit atrazine’s use was guided by two advisory committees made up entirely of EPA and Syngenta employees. 

Syngenta’s history with the EPA extends beyond this, though. The agricultural giant has come into hot water recently after an appellate court found that the EPA registered one of its insecticides, CTP, without meeting standards set up by the Endangered Species Act. Additionally, the company settled a lawsuit with the EPA in 2018, after exposing Hawaiian farmworkers to a pesticide known to cause illness and neurodevelopmental effects.

But back to atrazine. The chemical harms more parts of our aquatic ecosystems than just frogs. Atrazine inhibits photosynthesis in a number of aquatic plants. It is linked to DNA and endocrine system damage in aquatic invertebrates, and was associated with reproductive and developmental deficits in a number of fish species.

You do not have to be a fish or live in water to experience the detrimental effects of atrazine. Atrazine works as an endocrine disruptor in mammals. In human cells, it was found to act on SF-1, a human transcription factor involved in the the function of multiple endocrine glands as well as sex determination. Atrazine’s endocrine disruption, among other things, has been linked to an increase in testosterone’s conversion to estrogen in humans.

It should come as no surprise, then, that atrazine has been linked to other health defects. Current research explores its link to cancer as well as abnormal genital development. It is worth noting that due to ethical concerns, much of the research conducted on atrazine’s effects has been done on rats and not humans.

Corn growers, though, are not too concerned with the chemical’s continued use. Gary Marshall, CEO of the Missouri Corn Growers Association was quoted in a 2020 article as saying, “these products [triazine herbicides] are the most heavily researched compounds in the history of crop production and are among the safest to use for the environment, human safety and for the safety of aquatic life.” Gary Marshall also does work for the Triazine Network, which promotes the use of atrazine and other such chemicals.

Personally, my family has successfully grown corn on our farm for years without ever using atrazine. Atrazine’s continued use in the U.S. flies in the face of the science that proves its detrimental effects on our endocrine function, it harms our aquatic ecosystems, and it has a significant cost on taxpayers across the Midwest. It’s time the EPA, without the help of Syngenta and its army of paid scientists, review the science and determine how safe atrazine really is. 

Published by Elijah Deters

I am a freshman at the University of Louisville writing about healthcare and bioethics.

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