Birth control pills aren’t just having an effect on human reproduction: They’re dramatically reducing the fertility of male rainbow trout as well, according to a study by scientists in Washington state. In the study, adult captive trout were exposed to synthetic estrogen for two months, then spawned with a healthy female. Synthetic estrogen, which is commonly found in oral contraceptives, has been found in waterways across the country; the study found that exposure to it cut male trout fertility in half. Even the lowest exposure level — 80 times lower than concentrations found in the wild — had an adverse effect on fertility. The findings add to an ongoing debate about the effect of hormone-mimicking pharmaceuticals and pesticides that seep into sewage and wastewater. Currently, there are no regulations governing the release of such substances.