In recent years, there has been increasing public concern that chemicals in the environment are affecting human health by disrupting normal hormone function. These chemicals mimic or partly mimic the sex steroid hormones estrogens and androgens by binding to hormone receptors or cell signaling pathways. These chemicals are referred to as "endocrine disruptors", or "endocrine disrupting chemicals" in Europe and North America. In Japan, most people including the media call them "Environmental Hormones". Endocrine disruptors include natural products, pharmaceuticals, industrial products and environmental pollutants. Studies of wild shell-fish, fish, alligators, birds, whales, polar bears and experimental rodents have already clearly shown that disturbances of hormonal regulation by endocrine disruptors during fetal or post-natal development induced adverse effects on the animal's reproductive systems. Moreover, etiological studies have reported that a possible cause of regional declines in sperm counts, increases in abnormal spermatogenesis, increases in hypospadias and male reproductive disorders in humans are due to exposure to endocrine disruptors. However, the adverse effects of endocrine disruptors on humans are less clear, and are difficult to research and detect. Therefore we have investigated fetal exposure to endocrine disruptors in Japan by analyzing umbilical cords, and changes of testis weight and spermatogenesis in Japanese men by using analytical data of necropsy. We detected many endocrine disruptors including dioxins, PCBs, bisphenol A and phytoestrogens in human umbilical cords collected from normal newborns in Japan. Moreover, our analysis regarding the male reproductive condition shows an accelerated onset, peak and decrease of testis-weight that indicates the presence of subtle male reproductive disorders in Japan.
