Publisher Summary The endocrine system is comprised of a network of hormone-producing glands that synthesize and release carefully measured doses of these hormones, which in some instances are in the parts-per-trillion range. A large number of individual chemicals are demonstrated to be endocrine disruptors. Endocrine disrupting chemicals (EDCs) include pesticides, synthetic hormones, heavy metals, plasticizers, and other industrial chemicals. Chemicals toxic to the endocrine system can disturb its development as well as the development of organs that respond to endocrine signals. Due to the persistence of ED chemicals in body fat, exposures to the mother at any time during her life can result in transgenerational exposures to her offspring. It is suggested that endocrine disruptors are at least partially responsible for the decreases in human semen quality and quantity. A number of structurally different xenobiotic chemicals are estrogen mimics. These compounds include pesticides, industrial chemicals, and components of many plastics, including polystyrene and polycarbonate. Recent research into the biology of adipose tissue has revealed that adipose is not simply an energy storage site, but that it also secretes a variety of molecular species that affect the body's metabolism. With the knowledge that adipose tissue is an endocrine organ, it is suggested that it may be impacted by endocrine- disrupting chemicals and be a causative effect for type 2 diabetes. This connection is advanced by four-point arguments that are detailed in the chapter.