The endocrine system is the exquisitely balanced system of glands and hormones that regulates such vital functions as body growth, response to stress, sexual development and behavior, production and utilization of insulin, rate of metabolism, intelligence and behavior, and the ability to reproduce. Hormones are chemicals such as insulin, thyroxin, estrogen, and testosterone that interact with specific target cells. The interactions occur through a number of mechanisms, the easiest of which to conceptualize is the lock and key. For example, target cells such as those in the uterus contain receptors (locks) into which specific estrogenic hormones (keys) can attach and thereby cause specific biological actions, such as regulating ovulation or terminating pregnancy. Other endocrine disrupting mechanisms include binding hormone transport proteins or other proteins involved in signaling pathways, inhibiting or inducing enzymes, interfering with uptake and export from cells, and modifying gene expression.
Over the past 60 years, through technological advances a growing number of synthetic chemicals have been used in the production of almost everything we purchase. They have become a part of our indoor environment, found in cosmetics, cleaning compounds, baby and children’s toys, food storage containers, furniture and carpets, computers, phones, and appliances.
We encounter them as plastics and resins every day in our cars, trucks, planes, trains, sporting goods, outdoor equipment, medical equipment, dental sealants, and pharmaceuticals. Without fire retardants we would not be using our computers or lighting our homes. Instead of steel and wood, plastics and resins are now being used to build homes and offices, schools, etc. A large portion of pesticides are endocrine disruptors. What this constant everyday low-dose exposure means in terms of public health is just beginning to be explored by the academic community.
To date, no chemical in use has been thoroughly tested for its endocrine disrupting effects. Traditional toxicological testing protocols were not designed to test for endocrine disruption and to test at ambient or low exposure levels.