Tyrone Hayes, Ph.D., Professor in the Department of Integrative Biology at the University of California, Berkeley, shares his research on the widely used herbicide Atrazine and its disturbing effects on frogs, the environment, and on public health. We learn that Atrazine is the most widely used herbicide in North America. Atrazine is used throughout the United States to control weeds in agricultural fields, residential lawns, Christmas tree farms, and, golf courses, despite evidence of its toxic nature. Professor Hayes’ research published in Narture magazine shows that there is enough Atrazine in rainwater in Iowa to make male frogs “yolk eggs in their testes.” This module shows what can happen when a company in Switzerland is allowed to market their products in America when they can not be sold in Switzerland or most of Europe.