There is much recent evidence of a sharp rise in the incidence of testicular and other reproductive cancers, of a dramatic fall in sperm counts in Europe and America over the last fifty years, of an increase in sex-organ abnormalities in baby boys and of extraordinary changes to wildlife, including signs of feminization or even changing sex. Experiments suggest a common link between these changes: they can all be affected by exposure to the female hormone oestrogen. It has also been discovered that many man-made chemicals can act like weak oestrogens, and we are all eating, drinking and bathing in these chemicals. Deborah Cadbury examines the chilling evidence and presents the views of leading scientists in the field.