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.
Hormonal breast enhancement
Androgens, such as testosterone and dihydrotestosterone (DHT), powerfully suppress the action of estrogen in the breasts. At least one way that they do this is by reducing the expression of the estrogen receptor in breast tissue. In women with complete androgen insensitivity syndrome (CAIS), who are completely insensitive to androgens and have only modest levels of estrogen (50 pg/ml), the relatively low levels of estrogen are capable of mediating significant breast development, and the breast sizes of CAIS women, on average, are in fact actually larger than those of non-CAIS women. In males treated with antiandrogens, gynecomastia (enlargement of the breasts in males) and mastodynia (breast tenderness/pain) commonly occur. Antiandrogens, for instance spironolactone, are also known to cause breast enlargement and mastodynia in women. Some examples of widely used and highly-potent antiandrogens include cyproterone acetate and bicalutamide.