Much has changed since Science's Next Wave heard from Tyrone Hayes 8-and-a-half years ago. The son pictured on his right knee in the photo accompanying the article he wrote for Next Wave, "An Experiment Without Controls," is now as big as he is. Hayes's career has also matured: He has become the youngest professor at the University of California, Berkeley, earning tenure at an age--30--when most scientists are still postdocs and many are graduate students.

Over the last 8-and-a-half years Hayes also earned national attention by fighting a widely publicized battle with chemical giant Syngenta over his investigations of the environmental impact of the herbicide atrazine, a battle that, he says, temporarily engulfed him.

All in the Family

Blending research, mentoring, and family responsibilities can be tricky, Hayes says, attributing his success as a scientist and a family man to two related values: "balance and love." Hayes likes to strike a balance by blending his passions. He finds ways to involve his kids in his research and his research in his teaching. Even the unpleasantness of his ordeal with Syngenta was balanced out by scientific discoveries and publications.

For Hayes, there’s little separation between family and science. Waking at 5 a.m. allows him to work a full day, shuttle his kids to and from school, and still enjoy some family time. The children have developed a love of biology by accompanying their father on collecting trips, and he frequently uses them as examples to explain scientific concepts to his students. While lecturing on urination, sweating, and hormonal control of salt, Hayes uses his daughter’s experience as an example, talking about how her body reacted when she collected animals with him in the desert when she was two years old.

"It not only allows me to spend time with my daughter doing my research, but it gives me an interesting lecture to my students," Hayes says. "It also teaches them that I’m a real person with a real family when I go home."

Mentoring Isn’t Just for the Classroom

The ability to connect with students earned Hayes the Distinguished Research Mentoring of Undergraduates award from Berkeley in 2001. "I’ve had great graduate students," Hayes says, "but I’ve also had an amazing program for undergraduates." Hayes says he treats his students like he was treated as an undergraduate at Harvard, allowing them to do more than is typically expected of undergraduates. He credits his huge undergraduate contingent--he estimates he’s had 60 undergraduate researchers since 1997--with keeping his lab full of thousands of specimens of frogs.

Hayes has also practiced his blending magic as a departmental administrator, working hard to recruit a more diverse group of graduate students to his department of integrative biology. Increasing the ethnic diversity in science is important to him because, he believes, people from different backgrounds have different perspectives and take different approaches to the same problem, making science better. Hayes also promotes diversity in his lab and lecture classes on human endocrinology. (He also teaches other advanced courses in endocrinology.)

Finally, Hayes blends his science with the public sector, taking his scientific concerns out into the community. What would an endocrinologist who specializes in amphibians have to say to the public? Plenty: Their permeable skin and aquatic habitat make amphibians early indicators of water contamination risks that can be extrapolated to human health risks. "It’s important in terms of social responsibility," he says.

"That Which Does Not Kill Me, Makes Me Stronger"

Teaching, Hayes says, helps him focus his reasoning and therefore his research. "I really think the two balance each other if you do it properly." He combines ecological, physiological, and molecular approaches to explain how steroid hormones affect amphibian development, especially metamorphosis and sexual differentiation. What makes his lab unique is the fieldwork: Lab students and staff capture wild frogs and develop colonies. Hayes once rented an 18-wheeler and drove thousands of gallons of water from a pond to use in the lab.

But it is Hayes’s work showing that the chemical atrazine feminizes male frogs by stimulating estrogen production that produced a firestorm and made him a science celebrity. It was for that work that Hayes received the Jennifer Altman Foundation prize for integrity in science, but the work brought on the ire of Syngenta and a continuing controversy (see box).

In 1998, a company called Ecorisk hired Hayes on Syngenta’s behalf to test the effects of atrazine--the second most prolific herbicide in the U.S.--on frogs. Hayes found that at low doses--below the 3 parts per billion the EPA allows in drinking water--atrazine hampers larynx development in male frogs. Ecorisk requested further study, but, according to Hayes, didn’t provide funding for that study. Using other sources, Hayes continued the work and found at still lower doses--as low as 0.1 parts per billion--the male frogs’ testes developed into ovaries and produced eggs. Frustrated with what he believes was an attempt to bury data, he quit the Ecorisk project.

About Atrazine and Frogs

It seems that no scientific consensus has been reached on the effects of atrazine on frogs. Following the controversy over Hayes's work and Syngenta's response, an Environmental Protection Agency (EPA) Scientific Advisory Panel (SAP) evaluated 17 studies of the effects of atrazine on amphibians. The evaluation uncovered "confounding effects across all of the studies"--including Hayes's--"that limited, if not precluded, the utility of the data," as EPA scientist Thomas Steeger was quoted in a February 2004 news article in the journal Environmental Science and Technology ( ES&T). Hayes has accused EPA of being influenced by Syngenta. Other studies, including one by James Carr of Texas Tech University in Lubbock, which was also funded by Ecorisk, have reached conclusions similar to Hayes's, though the effects were observed at much higher doses.

Hayes continued his studies, however, and published the results in the Proceedings of the National Academy of Sciences, Environmental Health Perspectives, and as a brief in Nature. But Hayes’s former Ecorisk colleagues--all university professors--issued press releases claiming that his data were not replicable.

Eventually, several independent studies upheld Hayes's findings. But in 2003, the Environmental Protection Agency (EPA) approved atrazine’s Interim Re-registration Eligibility Decision (IRED), allowing its continued sale in the U.S. with no significant restrictions.

Through the good and the bad, Hayes loves what he does. "It’s about the balance, and it’s also about loving what you do because it’s relentless, it’s competitive, and it’s hard."

Clinton Parks is a writer for MiSciNet and may be reached at