ABSTRACT
I. INTRODUCTION During the late 1950s and early 1960s, normally rare but extremely severe limb malformations were observed in an unusually high incidence in babies in a number of countries. Thousands of such births occurred before it was determined that thalidomide, a sedative given to pregnant mothers for hyperemesis gravidarum, was responsible for the defects (1). Less dramatically, but no less important, the infertility rate in couples aged 15-24 years increased threefold between 1965 and 1982 (2). The cause of this increase remains unknown, but is thought to be due to increased exposures to various exogenous chemicals. These examples illustrate both the importance of and the difficulty in identifying com pounds that can affect reproduction and fetal development.
