Tyrone B. Hayes

PhD in Integrative Biology at the University of California, Berkeley

University of California, Berkeley


"Transformations in Environmental Endocrine Disrupters"


Dr. Tyrone B. Hayes's work is transforming biology one battle at a time. From a very early age, Tyrone knew that he was interested in biology, amphibians in particular. Always fascinated by frogs & toads, this facination has turned into a reality and a career. Dr. Hayes's work paves the way for an integrative approach to understanding how an organism reacts to changes in its environment.

His work includes studies on how exogenous hormones & endocrine disruptors influence developing tadpoles. Recently his work has gained international recognition for results demonstrating how atrazine, a wildly used pesticide which is found in groundwater, local streams & ponds, has been shown to alter reproductive development in frogs even at extremely low levels. Beyond his integratice, conscientious & conservational work, Tyrone has acted as a role model to minorities wanting to enter science. He has won numerous teaching awards, conservation awards & recognition as a leader in the scientific community.

Selected Publications

Hayes, TB et al. Atrazine-induced hermaphroditism at 0.1 ppb in American leopard frogs (Rana pipiens): laboratory and field evidence. Environ Health Perspect. 2003 Apr, 111(4):568-75.

Hayes, TB et al. Herbicides: feminization of male frogs in the wild. Nature. 2002 oct 31; 419 (6910): 895-6.

Hayes, TB et al. Hermaphroditic, demasculanized frogs after exposure to the herbicide atrazine at low ecologically relevant doses. Proc Natl Acad Sci USA 2002 Apr 16; 99(8): 5476-80.

Hayes, TB. Sex determination and primary seex differentiation in amphibians: genetic & developmental mechanisms. J. Exp. Zool. 1998 Aug 1; 281(5):373-99


National Geographic article: http://www.nationalgeographic.com/emerging/tyroneHayes.html

From Beyond curiosity: http://www.mindfully.org/Pesticide/2002/Tyrone-Hayes-Curiosity4nov02.htm

The story of Sygenta and Tyrone Hayes at UC Berkeley: http://www.mindfully.org/Pesticide/2003/Syngenta-Tyrone-Hayes31oct03.htm