Enhanced effects by mixtures of three estrogenic compounds at environmentally relevant levels on development of Chinese rare minnow (Gobiocypris rarus)

The combined effects of 17β-estradiol, diethylstilbestrol and nonylphenol at environmentally relevant levels were studied on development of Chinese rare minnow. No effects on hatchability of embryos, survival of larvae, body length and body weight were found in the fish exposed to the single chemicals and their mixtures. But significant vitellogenin induction and testis somatical index reduction were observed in adult males exposed to the mixtures. Meanwhile, the sex ratio of adult fish skewed to female was found in the fish exposed to high concentration of the mixture. These results revealed not only that the co-exposure of xenoestrogens can enhance the adverse effects on the development of fish, but that the adverse effects were induced by co-exposure of xenoestrogens below the threshold of similar detectable effects for single xenoestrogen. The observations in the present study highlight the potential ecological hazard posed by the coexistence of xenobiotics in the realistic aquatic environment.