Endocrine disruptors are chemicals which interfere with endocrine system function. The endocrine system consists of glands and the hormones they produce that guide the development, growth, reproduction, and behavior of human beings and animals. Some of the endocrine glands are the pituitary, thyroid, and adrenal glands, the female ovaries and male testes. Hormones are biochemicals, produced by endocrine glands, that travel through the bloodstream and cause responses in other parts of the body. The Endocrine Disruptor Screening Program will focus on the estrogen, androgen and thyroid hormones.
Androgens are substances, usually hormones, responsible for male sex characteristics.
Testosterone, the sex hormone produced by the testicles, is an androgen. The thyroid gland secretes two main hormones, thyroxine and triiodothyronine, into the bloodstream. These hormones stimulate all the cells in the body. Hormones can produce both positive and negative effects. For example, some types of breast cancer are exacerbated by estrogen, but studies also indicate that estrogen has a protective effect in combating heart disease and osteoporosis-related fractures in older women.