Everything changed for Dr. Tyrone Hayes when in 1998, the largest chemical company in the world asked him to use his expertise to try and understand if its top-selling product interfered with the hormones of frogs.

The company: Syngenta. The product: weedkiller atrazine.

Hayes, an American biologist and professor of Integrative Biology at University of California, Berkeley, discussed in his nearly 16-minute TEDxBerkeley talk the results of exposing African clawed frogs in his lab to atrazine. He presented an image up on the big screen of frog testes, showing a considerable difference between the controlled and exposed groups, and said:

“The controlled testes, if you look under the microscope, is full of sperm soldiers ready to go. The atrazine-treated testes, the testicular tubules are filled with cellular debris.”

Hayes explained how after exposure to atrazine, frogs that were genetic males became completely functioning reproductive females. In another frog species, he showed the gonads with “eggs that are bursting through the surface of the male’s testes.”

Yikes.

Read ‘Atrazine’s Dark Secrets Reemerge in Must-See TEDx Talk’

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