Citation:

Cole, A., J. Cavallin, J. Beihoffer, B. Blackwell, D. Ekman, A. Jastrow, J. Kinsey, K. Keteles, J. Parman, D. Winkelman, AND Dan Villeneuve. Evaluating effects of bioactive contaminants related to waste water treatment plant effluent on the South Platte River. SETAC North America, Sacramento, CA, November 04 - 08, 2018.

Impact/Purpose:

US surface waters contain complex mixtures of chemical contaminants. While concentrations of these contaminants can be measured and monitored, data needed to understand the ecological hazards they may pose are often lacking. The present study used a combination of chemical analyses, cell-based assays, and molecular responses in caged fish to better understand the relevance and potential ecological significance of three classes of biologically-active chemicals. Ranking among the most contaminated rivers in a recent nation-wide survey of chemical contamination in US streams, this research on the South Platte River is expected to lead to better understanding of appropriate ecological benchmarks for estrogenic, stress hormone-like, or fatty acid metabolism-regulating contaminants in US surface waters and inform Regions, states, and EPA program offices charged with protecting the nations aquatic ecosystems from harmful effects of chemicals.

Description:

The South Platte River near Denver Colorado ranks among one of the most highly contaminated streams examined in a recent nationwide survey. The present research characterizes the distribution of three classes of biologically-active contaminants along a waste water impacted reach of the river. By comparing results from chemical analyses, cell-based assays, and molecular responses in fish, we seek to gain a better understanding of what levels of these three classes of contaminants may warrant concern, and associated management actions by local, state, and federal stakeholders. Previous studies have shown the South Platte River in Denver, CO, contains numerous organic contaminants including biocides and pharmaceuticals at concentrations that rank among the highest in the nation. Regarded as chemicals of emerging concern (CECs), some of these contaminants can disturb biological pathways in exposed species. For example, cell-based estrogen assays revealed high estrogenic activity (31-35ng/L EE2-EQ) in water samples collected from the S. Platte downstream of a large waste water treatment plant (WWTP), compared to the reference site (< detection limit). In addition, male fathead minnows (Pimphales promelas) caged at sites downstream of the effluent showed higher levels of hepatic vitellogenin mRNA expression (14-43fold) than the reference site fish. In more recent studies, Attagene multifactorial assay results have shown several detectable biological activities downstream of the WWTP. These activities included estrogen receptor (ER)-mediated activity as previously documented, but also glucocorticoid receptor (GR)-, and peroxisome proliferator activated receptor gamma (PPAR?)-mediated activities, among others. The first objective of the present work was to better characterize the spatial and temporal distribution of GR and PPAR?-related bioactivity along the river using in vitro bioassays and Attagene multifactorial assays. Initial results from surface water samples collected in May and June 2018, show high levels of ER (3ng/L E2-EQ) and GR (150ng Dex-EQ/L) activity downstream of the WWTP. However, PPAR?-mediated activity was barely detectable at most sites. Our second objective was to analyze GR and PPAR-related gene expression in fathead minnows exposed in situ in the S. Platte River to gather evidence concerning potential in vivo impacts in relation to the biological activity detected in vitro. In August 2018, fathead minnows were caged for five days at five different sites along the S. Platte River in Denver, and a reference site in Clear Creek near Golden, CO. After exposure, skin mucus, muscle tissue, plasma, livers, gonads, and brains, were sampled for future analysis including metabolomics and gene expression. Composite water samples representing time-integrated exposure over 5 days were collected for chemical analysis and in vitro bioassay. Results provide new insights into the significance of GR-and PPAR? active contaminants in this system.

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