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.
High-dose estrogen
Estrogens are agonists of the estrogen receptors (ERs), the biological target of endogenous estrogens such as estradiol. When used in high doses, estrogens are powerful antigonadotropins, strongly inhibiting secretion of the gonadotropins luteinizing hormone and follicle-stimulating hormone from the pituitary gland, and in men are able to completely suppress gonadal androgen production and reduce testosterone levels into the castrate range. This is most of the basis of their use in prostate cancer and benign prostatic hyperplasia. When estradiol or an estradiol ester is used for HDE in men, levels of estradiol of at least approximately 200 pg/mL are necessary to suppress testosterone levels into the castrate range.