A wide, range of chemicals can affect population success, by interfering with the endocrine systems of animals and inducing, for instance, alterations of the reproductive processes. They can either mimic or disturb the action of endogenous estrogens by interference with estrogen receptor mediated processes.
Although the interference of chemicals with the action of estrogens has attracted particular attention, very few studies have concentrated on the antiestrogenic activities of a variety of non steroidal substances. For example, chemicals that induce *cytochrome P450 1 A (CYP 1 A) (e.g. dioxins and PAHs) show a strong antiestrogenic effect in fish by reducing the estrogen dependent synthesis of the yolk precursor vite116genin, as it has been shown in the initial fellowship.
Therefore, these substances may affect egg quality and reproductive success. This effect is mediated through the interaction of these xenobiotics with the aryl hydrocarbon receptor and the subsequent induction of CYP 1A.