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Pathway-based approaches for assessment of real-time exposure to an estrogenic wastewater treatment plant effluent on fathead minnow reproduction
Citation:
Cavallin, J., K. Jensen, M. Kahl, Dan Villeneuve, K. Lee, A. Schroeder, J. Mayasich, E. Eid, K. Nelson, R. Milsk, B. Blackwell, J. Berninger, C. LaLone, C. Blanksma, T. Jicha, C. Elonen, R. Johnson, AND G. Ankley. Pathway-based approaches for assessment of real-time exposure to an estrogenic wastewater treatment plant effluent on fathead minnow reproduction. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY. Society of Environmental Toxicology and Chemistry, Pensacola, FL, 35(3):702-716, (2016).
Impact/Purpose:
Wastewater treatment plant (WWTP) effluents are known contributors of chemical mixtures into the environment. Of particular concern are endocrine-disrupting compounds, such as estrogens, that can affect exposed organisms. The present study examined reproductive effects of exposure to a historically estrogenic WWTP effluent. A 21-d reproduction study using fathead minnows was conducted on-site at a WWTP using a continuous flow-through system, delivering final effluent in real-time. Fathead minnow breeding pairs were exposed to control water and three effluent concentrations (5%, 20%, and 100%). Molecular and biochemical endpoints representing key events along adverse outcome pathways linking estrogen receptor activation, and other molecular initiating events, to reproductive impairment were examined. Additionally, analytical chemistry results were used to construct a chemical-gene interaction network to aid in targeted gene expression analyses. Cumulative fecundity was significantly reduced in fish exposed to 100% effluent but increased in those exposed to 20% effluent, the approximate dilution factor in the immediate receiving waters. Although in vitro analyses, analytical chemistry, and biomarker responses confirmed the effluent was estrogenic, estrogen receptor agonists were unlikely the primary driver of impaired reproduction. The results provide insights into the significance of pathway-based effects with regard to predicting adverse reproductive outcomes.
Description:
Wastewater treatment plant (WWTP) effluents are known contributors of chemical mixtures into the environment. Of particular concern are endocrine-disrupting compounds, such as estrogens, that can affect hypothalamic-pituitary-gonadal axis function in exposed organisms. The present study examined reproductive effects of exposure to a historically estrogenic WWTP effluent. A 21-d reproduction study using fathead minnows was conducted on-site at a WWTP using a continuous flow-through system, delivering final effluent in real-time. Fathead minnow breeding pairs were exposed to control water and three effluent concentrations (5%, 20%, and 100%). Molecular and biochemical endpoints representing key events along adverse outcome pathways linking estrogen receptor activation, and other molecular initiating events, to reproductive impairment were examined. Additionally, analytical chemistry results were used to construct a chemical-gene interaction network to aid in targeted gene expression analyses. Cumulative fecundity was significantly reduced in fish exposed to 100% effluent but increased in those exposed to 20% effluent, the approximate dilution factor in the immediate receiving waters. Male vitellogenin concentrations increased in a dose-dependent manner with effluent concentration; however, fertility was not impacted. Although in vitro analyses, analytical chemistry, and biomarker responses confirmed the effluent was estrogenic, estrogen receptor agonists were unlikely the primary driver of impaired reproduction. The results provide insights into the significance of pathway-based effects with regard to predicting adverse reproductive outcomes.
