Endocrine Abstracts

Differentiation of male reproductive system is guided by testicular hormones and growth factors secreted during fetal development under gonadotropin control. Disruption of testicular hormone production or action leads to gonadal dysgenesis and maldevelopment of external genitalia. Cryptorchidism and hypospadias are the most common birth defects in boys, and both conditions can arise as a consequence of anti-androgenic disturbance during development. Both of them are also associated with poor semen quality and testicular cancer, suggestion similar pathogenetic pathways. Animal experiments show robust evidence that inhibition of androgen synthesis or action causes abnormalities in testicular and genital development. Chemicals with different mechanisms of action towards declined androgen activity work in an additive fashion. Therefore even small amounts of anti-androgens can add a critical dose to the total anti-androgenic load. While this is well documented in experimental animals, there is limited evidence on human harm. This is due to challenges in epidemiology to demonstrate causal relationships, albeit there are many examples of associations of chemical exposures with reproductive disorders.