Xenoestrogen
Xenoestrogens are a type of xenohormone that imitates estrogen. They can be either synthetic or natural chemical compounds. Synthetic xenoestrogens include some widely used industrial compounds, such as PCBs, BPA, and phthalates, which have estrogenic effects on a living organism even though they differ chemically from the estrogenic substances produced internally by the endocrine system of any organism. Natural xenoestrogens include phytoestrogens which are plant-derived xenoestrogens. Because the primary route of exposure to these compounds is by consumption of phytoestrogenic plants, they are sometimes called "dietary estrogens". Mycoestrogens, estrogenic substances from fungi, are another type of xenoestrogen that are also considered mycotoxins.
Estrogen (medication)
An estrogen is a type of medication which is used most commonly in hormonal birth control and menopausal hormone therapy. They can also be used in the treatment of hormone-sensitive cancers like breast cancer and prostate cancer and for various other indications. Estrogens are used alone or in combination with progestogens. They are available in a wide variety of formulations and for use by many different routes of administration. Estrogens are one of three types of sex hormone agonists, the others being androgens/anabolic steroids like testosterone and progestogens like progesterone.
Side effects of estrogens include breast tenderness, breast enlargement, headache, nausea, fluid retention, and edema among others. Other side effects of estrogens include an increased risk of blood clots, cardiovascular disease, and, when combined with most progestogens, breast cancer. In men, estrogens can cause breast development, feminization, infertility, low testosterone levels, and sexual dysfunction among others.
Estrogens are agonists of the estrogen receptors, the biological targets of endogenous estrogens like estradiol. They have important effects in many tissues in the body, including in the female reproductive system (uterus, vagina, and ovaries), the breasts, bone, fat, the liver, and the brain among others. Unlike other medications like progestins and anabolic steroids, estrogens do not have other hormonal activities. Estrogens also have antigonadotropic effects and at sufficiently high dosages can strongly suppress sex hormone production. Estrogens mediate their contraceptive effects in combination with progestins by inhibiting ovulation.
Estrogens were first introduced for medical use in the early 1930s. They started to be used in birth control in combination with progestins in the 1950s. A variety of different estrogens have been marketed for clinical use in humans or use in veterinary medicine, although only a handful of these are widely used. These medications can be grouped into different types based on origin and chemical structure. Estrogens are available widely throughout the world and are used in most forms of hormonal birth control and in all menopausal hormone therapy regimens.