Herbicide atrazine linked to feminization of frogs: 10 percent of males became fully viable females

By Christy Prais June 22, 2023

In a recent interview with Jordan B. Peterson, presidential candidate Robert F. Kennedy Jr. said that he thinks many of the causes of sexual dysphoria, particularly with boys, are coming from chemical exposure.

In particular, he mentioned the widely used herbicide atrazine.

YouTube has since taken the video down, claiming that it violates the platform’s community guidelines. It is available on Rumble, however.

In the now-censored June 5 interview, Peterson and Kennedy discussed a wide range of topics including Kennedy’s presidential bid. When the conversation turned to environmental issues, Kennedy noted that the “huge levels of depression” seen in today’s kids, as well as “a lot of the sexual dysphoria that we’re seeing,” may be the result of toxic chemicals.

“These kids are swimming through a soup of toxic chemicals today, and many of those are endocrine disruptors,” Kennedy said.

Kennedy said that one of the big issues is atrazine, which he says can be found “throughout our water supply.” He went on to reference a study in which male frogs were exposed to atrazine in a tank, leading to their chemical castration and forced feminization.

Even more concerning, he noted that the study found 10 percent of the male frogs turned into “fully viable females, able to produce viable eggs.”

“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.

The Science

The study that Kennedy referred to was led by Tyrone B. Hayes, professor of integrative biology at the University of California, Berkeley. It was published in March 2010 in the Proceedings of the National Academy of Sciences.

The study noted that atrazine is one of the most commonly used pesticides in the world, as well as the most commonly detected pesticide contaminant. It taints ground, surface, and drinking water and can travel via rainfall more than 620 miles from its application site.

The authors stressed that the herbicide is a potent endocrine disruptor, even at low levels. Previous studies showed adverse effects that included hermaphroditism, reduced testicular volume, and lowered testosterone.

The herbicide is also associated with both the demasculinization and feminization of male amphibians.

The study examined the long-term effects of atrazine on reproductive function in a genetically male population of African clawed frogs.

The male frogs were exposed to 2.5 parts per billion (ppb) of atrazine starting when they were tadpoles and continuing for up to three years after they metamorphosed into adults.

Ninety percent of the atrazine-exposed males appeared male, but suffered from depressed testosterone, decreased breeding gland size, decreased sperm production, feminized laryngeal (vocal) development, suppressed mating behavior, reduced spermatogenesis, and decreased fertility.

Functionally Female Frogs

Significantly, after exposure to atrazine, 10 percent of the genetic males developed into fully functional females with ovaries, producing viable eggs.

Two of the male-turned-female frogs were mated with control males and produced offspring. Further testing confirmed that these atrazine-exposed male frogs, although now functionally female (having undergone complete feminization) were, in fact, still chromosomal males.

In a 2018 keynote presentation, Hayes explained that exposure to atrazine induces the activation of an enzyme called aromatase. Aromatase converts androgens, which are involved in male sexual development, to different forms of the female hormone estrogen. In the atrazine-exposed frogs, aromatase converted testosterone into estrogen, leading to the feminization of male frogs.

According to Hayes, mammals—including humans—will not have the same extreme egg-producing reaction as some reptiles and amphibians do when exposed to atrazine. However, he noted that aromatase induced by atrazine exposure promotes breast cancer and prostate cancer.

Big Pharma, Big Herbicides

In fact, aromatase is so important as a cause of breast cancer that one of the leading treatments for breast cancer is a non-steroidal aromatase inhibitor called Letrozole, Hayes said.

The developer of Letrozole is pharmaceutical giant Novartis AG.

Interestingly, in a 2003 toxicological profile, the Agency for Toxic Substances and Disease Registry (ATSDR) lists Novartis Crop Protection, Inc. as one of six companies registered to produce products (pdf) containing atrazine.

Novartis Crop Protection was an affiliate of Novartis AG . . .

[SNIP]