Endocrine disruptors and timing of human exposure.

A gradual decline in human fertility coincides with intensive industrial and agricultural development and the concomitant release of chemical waste into the environment. Among these chemicals are endocrine disruptors (EDs) which, in minute doses, have detrimental effects on reproductive health. Human exposure to EDs varies with age. Adults are exposed mainly through the ingestion of contaminated drinking water, meat, fat-dairy products and breathing polluted air. Infants are exposed to EDs through breast milk, baby products, and polluted air. Their abilities to detoxify xenobiotics are not mature yet and blood-brain barrier is not entirely developed, thus EDs may enter the central nervous system easily. Fetuses are exposed to EDs through the placenta. The most harmful effects on reproduction occur when embryos are exposed to them during "critical windows of development", leading to irreversible, pathological changes in adult life. To create a healthier environment, scientific research must be translated into preventive policy legislation.