Antiandrogens are antagonists to androgens (the hormone). They were first discovered in 1960s. Androgen hormones are steroid hormones known to stimulate and control the male characteristics in vertebrates; this includes male secondary sexual characters and sex organs. Antiandrogens alter the androgen pathway by blocking the appropriate receptors, competing for binding sites on the cell's surface, or affecting androgen production. Many industrial chemicals, pesticides and insecticides are known to show antiandrogenic effects. Certain plant species are also well known to show antiandrogenic effects.