| Popis: |
Confined animal feeding operations (CAFOs) are a source of endocrine disrupting compounds (EDCs) in the aquatic environment and introduced there through agricultural runoff and insufficient waste storage systems. This study used the three compounds 17α-ethynylestradiol (EE2), 17β- trenbolone (TB), and atrazine (Atr) alone and in a mixture representing a simulated CAFO runoff. Laboratory exposures were performed in order to assess if early life exposure during the period of sexual differentiation to CAFO runoff altered gonadal development in western mosquitofish (Gambusia affinis). Juveniles were exposed to low and high concentrations of EE2 (50 or 250 ng/L), TB (10 or 50 ng/L), Atr (150 or 1,500 ng/L), or simulated CAFO runoff (50 ng/L EE2, 10 ng/L TB, and 150 ng/L Atr or 250 ng/L EE2, 50 ng/L TB, and 1,500 Atr) for 30-days followed by a 46-day recovery period. Gonadal histology was measured in adult males and females to assess stages of sexual development (i.e., oogenesis or spermatogenesis) and gonadal histopathology. All of the ovaries analyzed were in the maturing or mature stages of oogenesis, and all of the testes examined were in the intermediate or advanced stages of spermatogenesis. Intersex was observed in one individual exposed to 1,500 ng/L Atr. Ovarian histopathology was normal in all females, however testicular histopathology showed a loss of cyst structure leading to unbound interstitial sperm cells and unsynchronized cyst development in all males except the control fish. This study provided some evidence that exposure to simulated CAFO runoff and its individual compounds impaired testicular development. |
