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. Click here for a more detailed description of the endocrine glands and their functions. The U.S. EPA does not endorse any private sector Web site or exercise any editorial control over the information you may find at this location. Disruption of this complex system can occur in various ways. Other chemicals may block the effects of a hormone in parts of the body normally sensitive to it.