Wednesday, February 18, 2015 

From Silent Spring to Silent Night: A Tale of Toads and Men

MBH 216
7:00p

This year’s Scott A. Margolin ’99 Lecture in Environmental Affairs will be given by Tyrone B. Hayes, Professor of Integrative Biology at University of California, Berkeley.  The herbicide, atrazine, is a potent endocrine disruptor.  Dr. Hayes’ laboratory’s studies in amphibians have shown that atrazine both demasculinizes and feminizes exposed males at levels as low as 0.1 ppb. Their previous worked examined morphological effects, including the loss of androgen-dependent sexually dimorphic features, and the development of estrogen-dependent features in exposed males. These findings are consistent with an induction of aromatase, resulting in decreased androgen secretion and inappropriate estrogen synthesis and secretion. Their ongoing studies focus on behavioral effects in male frogs exposed throughout life and demonstrate both the loss of male reproductive behavior and the induction of female-typical behavior in exposed males. These data on amphibians and the proposed mechanism are consistent with findings across vertebrate classes, including humans, and raise concern about the role of this common environmental contaminant in reproductive hormone-dependent cancers and declining fertility in humans.