Introduction

WILDLIFE D.Andrew Crain,1 Andrew A.Rooney,2 Edward F.Orlando,2 and Louis

J.Guillette, Jr. 1 Department of Biology

Maryville College Maryville, TN 37804

2 Department of Zoology University of Florida Gainesville, FL 32611

Introduction

Over the past few decades, accumulating evidence has suggested that many environmental chemicals can alter reproduction, growth, and survival by changing the normal function of the endocrine system. The endocrine system is complex, with many organs contributing to a multifaceted regulatory system. This complexity obstructs the identification of the specific mechanisms through which endocrinedisrupting contaminants (EDCs) elicit their responses. The lack of an organized, mechanistic understanding of EDC effects provides perhaps the greatest impediment to this area of research (Rudel, 1997). Before considering how EDCs can alter the endocrine system, we must first have an understanding of normal hormone dynamics. Figure 1-1 presents a simplistic model of hormone dynamics, following hormones from production to excretion. Accurate assessment of an environmental chemical’s potential to alter the endocrine system depends on consideration of the entire hormone dynamic pathway.