| "Estrogen-like substances have been suspected to cause the feminization of wild fish in some rivers in Japan. To elucidate the influence of estrogen-like substances on fish, we placed two sets of the systems in a sewage treatment plant. Adult male medaka was exposed to a secondary treated water or an advanced treated water which is put sand filtration after secondary treatment. Flow rate and temperature of the water were controlled at 30L/hour and 26℃, respectively, and a light: dark cycle was maintained at 16:8 hours in the system. After two weeks exposure, vitellogenin concentration of each male medaka was measured. Vitellogenin was not detected from male medaka exposed the advanced treated water but detected from approximately 20% in male medaka exposed the secondary treated water." |
