Toxicity of 17α-ethinylestradiol and bisphenol A to the freshwater cnidarian Hydra vulgaris

Estrogens and estrogen mimics that enter the environment are known to present a serious threat to the development and reproduction of vertebrates by disrupting their normal endocrine function. There is also concern that such chemicals may be damaging to invertebrates. In this study, Hydra vulgaris, a member of the Cnidaria, an evolutionarily primitive invertebrates present before the divergence of the protostomes and deuterostomes, was exposed to the synthetic estrogen 17alpha-ethinylestradiol (EE2) and bisphenol A (BPA), both of which are known to be estrogenic in fish. Effects on polyp survival structure, and regeneration (and sexual reproduction for EE2) were examined and mortality was recorded at high concentrations, with 96-h LC(50)s of 3.8 mg/L and 6.9 mg/L for EE2 and BPA, respectively. The structure and physiology of polyps was adversely affected at concentrations greater than 58 mug/L EE2 and 42 mug/L BPA. There was a concentration-related inhibition of regeneration above 150 mug/L EE2 and 460 mug/L BPA. Sexual reproduction was only impaired at 500 mug/L EE2. These results clearly suggest that the signaling processes necessary for the control and regulation of cell movement and differentiation during normal development, regeneration, and sexual reproduction in H. vulgaris are not disrupted by estrogenic pollutants at low environmentally relevant concentrations.