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Atrazine is a commonly used herbicide in the U.S. The Environmental Protection Agency regulates how much is allowed in drinking water and evaluates potential ecological and human health risks.
No scientific studies in humans have linked atrazine exposure to gender dysphoria. It has been linked, in some studies, to birth defects and other reproductive health problems.
Robert F. Kennedy Jr.’s claim appears to be based on a 2010 University of California, Berkeley study that found that when male frogs were exposed to atrazine, some lost fertility and developed ovaries. Differences in human and frog biology mean these findings do not unilaterally extend to humans.
Are herbicides in the water causing children to become transgender?
That was the theory Democratic presidential challenger Robert F. Kennedy Jr. posed on a June 5 podcast.
"I think a lot of the problems we see in kids, and particularly boys, it's probably underappreciated how much of that is coming from chemical exposures, including a lot of the sexual dysphoria that we’re seeing," said Kennedy to podcast host and conservative commentator Jordan Peterson.
TikTok identified video from the podcast as part of its efforts to counter inauthentic, misleading or false content. (Read more about PolitiFact’s partnership with TikTok.)
"Sexual dysphoria" is not a medical term, according to experts, and Kennedy’s team did not respond to a request to clarify his meaning of that phrase. Gender dysphoria is the experience of distress that can occur when a person’s gender identity does not match their sex assigned at birth, and is common in transgender people.
In the podcast, Kennedy referred to a study that found that exposure to the herbicide atrazine in water caused some male frogs to develop female sex organs and become infertile. His description matches the details of a study published in 2010.
"If it’s doing that to frogs, there’s a lot of other evidence that it’s doing it to human beings as well," Kennedy said. He offered no examples of that evidence. Kennedy made similar comments on Joe Rogan’s podcast 10 days later.
But, with apologies to Kermit the Frog, there are some important biological differences between humans and frogs, and although atrazine may pose some human health risks, there is no evidence that atrazine exposure is linked to gender dysphoria in humans.
Kennedy’s team did not respond to requests for comment.
According to the U.S. Department of Agriculture, atrazine is one of the nation’s most commonly used herbicides. Atrazine, first registered for use in 1958, works by inhibiting photosynthesis on broadleaf plants and grasses. It is used mostly in large-scale agriculture by people who are government-certified in how to apply restricted-use pesticides.
Atrazine enters drinking water through agricultural runoff from row crops, the Environmental Protection Agency said. Row crops are annual food and fiber plants such as corn, soybeans, rice and cotton.
Under the Safe Drinking Water Act, the EPA regulates atrazine levels in drinking water. The legal limit is 0.003 milligrams/liter, or 3 parts per billion.
The EPA’s 2018 human health risk assessment of atrazine "found no risks of concern when evaluating all dietary exposure sources including drinking water." The agency identifies potential risks for children playing on lawns treated with the chemical, and occupational exposure to the herbicide.
But not everyone agrees with EPA’s assessment. Use of the chemical is banned in the European Union and many groups that advocate for biological diversity and food safety have opposed its use. The Federal Insecticide, Fungicide and Rodenticide Act requires the EPA to periodically reevaluate pesticides to stay up to date with the most recent science. In 2020, atrazine was re-approved with updated risk mitigation measures.
The decision prompted legal action from several organizations who felt the EPA made its decision without "substantial evidence." The EPA was allowed to reevaluate part of its decision and has proposed new risk mitigation efforts. After public comment, regulations on atrazine are expected to be finalized.
Concerns about atrazine center on its potential to disrupt hormones in the body. Atrazine exposure in humans has been linked to reproductive health issues including birth defects, and low birth weight. There is also research that suggests a link to kidney disease, wheezing, and higher body mass index in farmers who use the herbicide.
Although atrazine may pose health risks, no studies in humans have shown a link between atrazine exposure and gender identity or sexual orientation.
In his podcast discussion with Peterson, Kennedy described the same findings as a 2010 study from the University of California, Berkeley.
"If you, in a lab, put atrazine in a tank full of frogs, it will chemically castrate and forcibly feminize every frog in there," Kennedy said. "And 10% of the male frogs will turn into fully viable females able to produce viable eggs."
Kennedy’s description of the study was mostly accurate, and when it was first published, the study garnered quite a lot of attention. Its lead researcher, Tyrone B. Hayes, was profiled in The New Yorker. Reaction to the study also spawned a viral meme of right-wing Infowars podcaster Alex Jones shouting, "I don't like 'em putting chemicals in the water that turn the freaking frogs gay!"
To learn more, PolitiFact talked with Hayes, a professor at University of California, Berkeley’s Department of Integrative Biology.
He said he supports more research into atrazine’s health effects on animals and humans but said of Kennedy’s claim, "There are no data to really make that link. That's speculation."
He also explained key differences between humans and their amphibian friends. Both amphibians and fish, "have relatively permeable skin," Hayes said. "So, at a lower dose, they might absorb the compound more." Most people are mostly exposed to atrazine through drinking water, Hayes said. Exposure through the skin and lungs is more common in industrial applications.
When exposed to atrazine, humans are also more easily able to filter it out through urine. Frogs live in the water they urinate in and so are less able to escape long-term exposure.
Hayes also said that amphibians, along with fish and some reptiles, have more sexual fluidity.
"You can have a genetically male frog and give it estrogen and it'll grow an ovary," Hayes said. The same doesn’t apply to humans.
Hayes pointed to several studies of atrazine in mammals such as rats and mice that raise concerns about lowered testosterone and genital abnormalities. Although low levels of testosterone can cause health problems, like reduced sex drive, fatigue, increased body fat, and depression, it has not been associated with gender dysphoria or being transgender, experts said.
Experts still don’t know why some people are transgender, or why more young people are identifying as transgender or gender-nonconforming.
"There are no data that trans people prior to treatment have different hormone levels" than people who are not trans, said Dr. Joshua Safer, an endocrinologist and the executive director of the Mount Sinai Center for Transgender Medicine and Surgery.
Kennedy said the herbicide atrazine in the water supply is contributing to "sexual dysphoria" in children.
"Sexual dysphoria" is not a medical term and Kennedy’s team did not respond when we asked for clarification of that phrase. Gender dysphoria is the experience of distress that can occur when a person’s gender identity does not match their sex assigned at birth.
Some research suggests atrazine can harm human health, specifically related to reproductive health and hormones. But no scientific studies in humans link atrazine exposure to gender dysphoria.
A 2010 study in frogs that Kennedy appeared to refer to found evidence that atrazine exposure has a feminizing effect on frogs and can cause genetically male frogs to develop ovaries. But biological differences mean those findings cannot be unilaterally applied to humans. The frog study’s lead researcher said there is currently no data to support Kennedy’s claim.
We rate this claim False.
Interview with Tyrone B. Hayes, Professor at University of California, Berkeley’s Department of Integrative Biology, June 23, 2023
Email Interview with Dr. Joshua Safer, Executive Director of the Mount Sinai Center for Transgender Medicine and Surgery, June 27, 2023
Email Interview with Mikko Väänänen, Press Officer at the European Chemicals Agency, June 27, 2023
Email Interview with Dr. Alex Keuroghlian, Director of the Massachusetts General Hospital Psychiatry Gender Identity Program, June 27, 2023
Email Interview with Dr. Michelle Forcier, a Folx Clinician and professor of pediatrics at the Alpert School of Medicine at Brown University, June 26, 2023
Jordan B. Peterson Podcast, "Rekindling the Spirit of the Classic Democrat | Robert F. Kennedy Jr.," June 5, 2023
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Tweet, June 18, 2023
PolitiFact, "‘Gender dysphoria’: What it is, what it isn’t and how history has changed its view," May 22, 2023
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