Sexually disrupting effects of nonylphenol and diethylstilbestrol on male silver carp (Carassius auratus) in aquatic microcosms

Based on detected nonylphenol (NP) levels in aquaculture water, this study investigated sexually disrupting effects in mature male silver carp (Carassius auratus) exposed to NP and a positive control diethylstilbestrol (DES). The combined evidences of steroid hormone (17β-estradiol, estrone and testosterone) levels and hispathological pictures showed that NP (⩾10 μg/L) and DES could exert estrogenic effects through indirect mechanisms [i.e. increased estrogens levels (up to two times) and decreased androgen level in serum (down to 20–30%)], which might subsequently induce vitellogenin synthesis in liver. Environmental realistic concentrations of NP might be on the verge of inducing significant estrogenic effects in male silver carps. High amounts of NP and DES might be accumulated in fish serum, and the uptake by fish was possibly responsible for their quick attenuation in experimental tank water. NP and DES might have different metabolic mechanisms, the estrogenic effects of DES were more significant than those of NP.