Normal foetal development is determined in part by hormones. In fact, the same hormones guide development among all vertebrate animals. If these are disrupted, especially during a crucial stage of development, there can be permanent damage. The effects vary with the species and the chemical. The damage observed so far in wildlife includes obvious birth deformities, abnormal behaviour, reduced fertility, thyroid dysfunction, metabolic abnormalities, weakened immune systems, demasculinisation and feminisation.
Humans have a shared biology with other vertebrates and a shared contamination.
From the example of DES we already know that humans are vulnerable in the same way as fish and birds. DES was a drug given to pregnant women to prevent miscarriages. It caused no harm to the mothers but the daughters and sons exposed to DES early in foetal life suffered from a range of reproductive disorders that were not apparent until puberty or adulthood. These include vaginal cancer, reproductive tract abnormalities, abnormal pregnancies, abnormal sperm, reduced fertility and weakened immune system. The authors reckon that some of the problems in humans which have been increasing are likely to be the result of foetal exposure to hormone-disrupting pollutants.