Dr. Tyrone Hayes Tells a Tale of Toads and Men

The lecture hall was already packed ten minutes before Dr. Tyrone Hayes, a squat man with a prominent kinky beard, large silver dangle earrings,and an engaging aura of sassy humor, started his story. Over 150 students squeezed into the room even after the seats had all been taken, settling in the aisles and leaning against the walls, eager to learn about his controversial findings on the health consequences of atrazine, a common herbicide applied to corn.

Hayes, a professor of integrative biology at University of California Berkeley, was chosen as this year's Scott A. Margolin '99 lecturer in Environmental Affairs. His presentation, “From Silent Spring to Silent Night: A Tale of Toads and Men", took place in Bi-Hall last Thursday evening.

Hayes’ personal narrative began describing his curiosity as a little boy. He grew up as one of several children in a household with an annual income of $9,000, studying frogs in a little patch of forest by his grandmother’s home. He went on to earn an undergraduate degree in organismic and evolutionary biology from Harvard, and started teaching at UC Berkeley following his doctoral and postdoctoral work on the role of hormones in amphibian responses to environmental cues.

After the Swiss agribusiness, Syngenta, approached Hayes to test their product, atrazine, in 1997, he found that the chemical acts as a strong endocrine disruptor that adversely affects reproduction and health. His laboratory work with frogs revealed that atrazine demasculinizes and feminizes a significant percentage of exposed males at concentrations as low as 0.1 ppb.

Because the herbicide interferes with the secretion of androgen, a hormone crucial for male development, and enhances the production and secretion of estrogen, a female hormone, the amphibians lose their distinguishing sexual features. Atrazine-exposed male frogs had lower semen counts and malformed testes; some even developed female ovaries and generated eggs. Individuals that were once biological males began behaving and reproducing like females. The subjects also had a higher risk of developing estrogen-induced cancers.

Given that atrazine now contaminates vast expanses of fields and waterways, Hayes’ research has immense implications for environmental and human well-being. Amphibians are in rapid decline, as the title of his talk suggests. "Silent Night" refers to the disappearance of "ribbit"-ing frogs. Atrazine could be responsible for this. By drastically changing the population's sex ratio,  Hayes blamed atrazine for lowering the procreation rates of amphibians.

Human studies have also shown a correlation between exposure to atrazine and reproductive problems. Because reproductive mechanisms and results derived from amphibians are comparable across vertebrate classes, the demasculinizing, feminizing, and carcinogenic repercussions of the chemical could play a part in decreasing fertility and increasing cancer in humans.

These health impacts also intersect with issues of social injustice and structural violence. Workers who labor on farms that use atrazine belong to disadvantaged racial and socioeconomic minorities who do not have the means to minimize exposure to the chemical or deal with its effects. Additionally, poorer groups are more vulnerable to exposure through water because they cannot afford sophisticated filtration systems.

Syngenta, however, claims that atrazine is harmless. It has funded over 7,000 studies that conclude that there is insufficient evidence to identify the chemical as the cause of abnormalities relating to endocrine disruption. On the basis of his identity as an eccentric nonwhite producer of knowledge, the company has attempted to discredit Hayes and stop him from publishing his findings. It insists that his methodology is flawed, his sample sizes too small. It has even gone as far as investigating his background, plotting to ensnare him in a trap, and threatening violence against his family.

The EPA has directly stated that the social ramifications of agricultural chemicals have to be considered in the context of their economic value. Although Hayes has not backed down from speaking against the agrichemical industry and continues to irk it by propagating his research in a plethora of biological and general interest publications, he realizes that the data alone has little power. “It’s not about science,” he said. “It’s about politics and economics.”

Associate Professor of Chemistry, Biochemistry & Environmental Studies Molly Costanza-Robinson, who suggested Hayes as this year’s speaker, was pleased with the lecture. “He brought the science to life. He made it personal,” she said. “It’s only a subset of scientists that are both amazing in the science, but then also really speak to the broader environmental studies. I’ve known of his work for a long, long time. He’s a hero of mine. I thought he would be perfect. We felt like he would be able to bring in a lot of folk from the environmental justice aspect, from chemistry, from biology.”

Molecular biology major Emily Hoff ’15 also enjoyed the talk. “He did a good job taking a very scientific argument and creating it into a story that had scientific fact incorporated into something that was accessible to the general population,” she said.

She pointed out that Hayes’ lecture was important because it raised awareness about the environmental hazards we are exposed to daily. “My biggest takeaway was to be conscious of what I personally expose myself to,” she said. “It’s really important to realize that although these chemicals on the surface level might impact the growth of crops in a positive way, they can have some severe ramifications on human health and the health of the environment.”