Environmental estrogens are a variety of synthetic chemicals and natural plant compounds that are thought to mimic the female hormone estrogen. They may act like estrogens or may block the natural hormone.

The body’s estrogen controls the growth of cells by attaching to proteins called estrogen receptors throughout the body. Many environmental estrogens can attach to these same proteins, fooling the body or tissues by giving them an inappropriate “estrogen” signal. These compounds are found all around us. We eat them, drink them, breathe them and use them at work, at home and in the garden. They include pesticides such as the now-banned DDT, kepone, polychlorinated biphenyls (PCBs), natural plant products in our diet and the drug DES, which was widely used for more than 20 years beginning in the 1940s to prevent spontaneous abortions in women. In 1971, researchers showed that daughters of women who took DES had a high rate of a rare form of cervicovaginal cancer. DES’ common use as a growth promoter in cattle also was banned by the Food and Drug Administration in the 1970s.

NIEHS is supporting and conducting studies of environmental estrogen exposures, including a testing of the blood and urine of a representative group of Americans to determine how much of these chemicals are accumulating in the body. There is a possibility they might play a role in diseases such as cancers of the breast, uterus and ovaries, as well as endometriosis and uterine fibroids. There is also a possibility that some of these estrogen-like substances, such as the ones occurring naturally in vegetables, may be beneficial.