Multigenerational responses of Daphnia magna to Ethynylestradiol and Faslodex.

Select environmental contaminants can disrupt normal functions of aquatic invertebrate endocrine systems. While ecological risk assessments often rely on standardized laboratory toxicity tests to assess ecological impacts, these techniques may not be appropriate for endocrine active compounds, including select pharmaceuticals in the environment. Subsequently, multigenerational designs are recommended to assess organismal responses to low-level exposures to these compounds. The objective of this study was to investigate effects of a mammalian estrogen receptor agonist and antagonist on endocrine biomarkers and transgenerational life-history parameters of a model invertebrate, Daphnia magna. Results from this study suggest that the pharmaceuticals, Ethynylestradiol and Faslodex, model therapeutics designed to interact with vertebrate estrogen receptors, did not act through the ecdysone receptor in D. magna. Thus, toxicity Ethynylestradiol and Faslodex exerted on D. magna likely resulted from non-endocrine-mediated responses, which may reduce uncertainty in future assessments of invertebrate responses to endocrine active pharmaceuticals in the environment.