In the 1950s biologists began noticing unusual behavior and various reproductive health problems in wild animals. Environmental health analyst Theo Colborn was one of the first to start asking what those trends might mean for humans. In this podcast marking the 40th anniversary of Earth Day, Colborn discusses her research on the endocrine-disrupting effects of chemicals in the Great Lakes ecosystem—research that broke new ground in the field of environmental toxicology. Colborn, co-author of Our Stolen Future, now heads The Endocrine Disruption Exchange in Paonia, Colorado, and is a professor emeritus at the University of Florida in Gainesville. Visit the podcast webpage to download a full transcript of this podcast.