Two synthetic chemicals PCB and DDE exposure during pregnancy are being held responsible. Early puberty is linked to increased risk of breast cancer. Endocrine disrupters can either imitate or act as a hormone by activating estrogen receptor sites. They can bind with the receptor sites without activating them. This causes the hormones to be blocked from the receptor sites.
Steroids are a product of cholesterol.
Estrogens, progesterone, testosterone etc. Fatty acid derivatives, peptides and proteins. Pregnelone is secreted from cholesterol and rapidly secreted from the cell inactivated and excreted through urine or bile. Hormones can affect menopause, libido, impotence and fertility. Thyroid hormones are derived from the Amino acid tyrosine.