Environmental Causes of Birth Defects: The Hexachlorophene Issue

The use of epidemiologic methods to study chronic diseases has brought an increased awareness of the importance of environmental factors in the causes of those diseases. Epidemiologic evidence, usually of an indirect nature, suggests that many common cancers and birth defects have an important environmental component to their cause. The studies of congenital rubella and the thalidomide syndrome were milestones in our understanding of the environmental causes of birth defects, providing clear evidence that exposure of a pregnant woman to a teratogen can cause one or more birth defects in her offspring.

Since thalidomide and rubella, the concept of teratogenesis has broadened. Minor as well as major malformations are now called birth defects, and diseases with childhood and adolescent onset are now known to be caused by prenatal maternal exposure to environmental agents. Diethylstilbestrol is a case in point. The first evidence that diethylstilbestrol could harm the fetus (reported in