 A potential mechanism has been described in rats exposed to DDT or beta-estradiol in which GnRH pulsatile secretion was found to be increased.Oral exposure of female rats to xenoestrogens has been shown to cause pseudo precocious puberty (early vaginal opening and early first estrus).A study of dioxin in immature female rats induced early follicular development and phthalates are known to decrease the anogenital distance in newborn rats.