Though he still sees himself as “just a little boy who loves frogs,” Tyrone Hayes, Ph.D., an integrative biologist at the University of California, Berkeley, has spent a decade feuding with chemical giant Syngenta, manufacturer of the pesticide atrazine. Novartis, which eventually became Syngenta, asked Hayes to use his extensive knowledge of frog hormones to determine if atrazine was interfering with frogs in the environment.

It certainly wasn’t what they wanted to hear, but he found atrazine may be chemically castrating male frogs, essentially turning them into female frogs. When Hayes reported some of his troubling findings to the U.S. Environmental Protection Agency (EPA), including male frogs with eggs bursting out of their testicles — “I thought they would be interested, after all it was the No. 1 selling chemical in the world at the time,” he said — they stated it wasn’t an adverse effect that would prompt them to reevaluate the chemical.

Hayes resigned his contractor position with Syngenta after the company refused to allow him to publish the results of studies they had funded. After resigning, he obtained independent funding to repeat the research, which was subsequently published and found that atrazine causes hermaphroditism in frogs.

Syngenta attempted to discredit Hayes after the damaging research was released. However, as Hayes argues in the TED talk above, he follows Albert Einstein’s notion that “those who have the privilege to know, have the duty to act.”

Atrazine Shown To Be Harmful to Animals, Humans and the Environment

Hayes’ research hypothesized that atrazine turned on an enzyme (aromatase) that caused testosterone to be converted into estrogen. If you’re a male, this means that you won’t make sperm, but you will make estrogen, even though you shouldn’t.

According to Hayes and colleagues in research published in Nature in 2002, exposure to water-borne atrazine contamination led to “gonadal abnormalities such as retarded development and hermaphroditism” in 10 percent to 92 percent of male wild leopard frogs. Hayes published another study in 2010 in Proceedings of the National Academy of Sciences (PNAS), which similarly found:¹

“Atrazine-exposed males suffered from depressed testosterone, decreased breeding gland size, demasculinized/feminized laryngeal development, suppressed mating behavior, reduced spermatogenesis and decreased fertility.”

Yet, if atrazine is harming wildlife via the water supply, it stands to reason that it could harm humans as well. Indeed, Hayes cites research showing that men with higher levels of atrazine in their urine (the same level he and colleagues used to “chemically castrate” frogs — 0.1 parts per billion (ppb)) have lower sperm counts. Other research shows that workers who apply atrazine in agricultural fields have 24,000 times the atrazine level in their urine than was used to chemically castrate frogs.

He soon became involved in environmental justice, as he learned that most of the individuals being exposed to these high levels of atrazine are Latin American or Mexican American. The evidence also suggests atrazine exposure may contribute to a number of different cancers, specifically ovarian cancer, non-Hodgkin’s lymphoma, hairy-cell leukemia and thyroid cancer.

In addition, Hayes cited research showing an 8.4-fold increase in prostate cancer in males working in an atrazine factory — in a community that’s 80 percent African-American. Again, racial or ethnic minorities are disproportionately affected.

Atrazine Contaminates Drinking Water

As far as pesticides go, atrazine is the one most commonly found in U.S. drinking water. In 2012, Syngenta AG and its U.S. subsidiary were ordered to pay $105 million to filter the chemical out of Midwestern community water treatment operations providing drinking water to 52 million Americans.² The legal proceedings revealed that as many as 1 in 6 Americans was drinking atrazine-contaminated water. The $105 million settlement was really just a drop in the bucket when compared to the actual cost of filtering this chemical.

In 2010, the plaintiffs’ attorney, Stephen Tillery, said the 16 cities included in the original lawsuit had already spent about $350 million to filter it out. Since 2012, at least 1,085 other compensation claims over atrazine contamination have been filed against Syngenta, suggesting the problem is incredibly widespread.

Also disturbing, studies show a correlation between atrazine in drinking water and breast cancer incidence in Kentucky,³ whereas previous research on rats showed exposure to atrazine increased the incidence of mammary cancer.⁴

As Hayes pointed out, “This is an interesting problem, because breast cancer … is estrogen dependent and … aromatase … produces the estrogen during breast cancer that stimulates those breast cancers to grow and divide and turn into tumors and spread.” He then points out that the No. 1 treatment for breast cancer is a chemical called Letrozole, which works by knocking out aromatase and decreasing the estrogen that’s fueling the cancer. Hayes explained:

“That drug, though, has to work against the 80 million pounds of atrazine that we’re using every year … that does exactly the opposite. I got in trouble because I pointed out that Novartis Oncology, in the year 2000, offered treatments for cancer, including breast cancer, so the same company that gave us 80 million pounds of this contaminant associated with breast cancer was also selling a chemical that does the opposite to treat breast cancer.”