2006 Progress Report: Developing Rapid Assessment Tools to Evaluate the Biological Effects of Complex and Biologically Active Chemical MixturesEPA Grant Number: R832741
Title: Developing Rapid Assessment Tools to Evaluate the Biological Effects of Complex and Biologically Active Chemical Mixtures
Investigators: Schoenfuss, Heiko L. , Barber, Larry B. , Julius, Mathew L. , Norris, David O.
Institution: Saint Cloud State University , United States Geological Survey [USGS] , University of Colorado at Boulder
EPA Project Officer: Hahn, Intaek
Project Period: November 1, 2005 through October 31, 2008 (Extended to October 31, 2009)
Project Period Covered by this Report: November 1, 2005 through October 31, 2006
Project Amount: $599,640
RFA: Exposure Measurement Tools for Endocrine Disrupting Chemicals in Mixtures (2005) RFA Text | Recipients Lists
Research Category: Economics and Decision Sciences , Endocrine Disruptors , Health , Safer Chemicals
This project seeks to test the hypothes is that mixtures of estrogenic compounds will have adverse effects on survival and reproduction of aquatic vertebrates that cannot solely be accounted for by the summation of individual effects. Three objectives will be completed to test the above hypothesis and develop rapid assessment biomarkers to evaluate effects of complex, biologically active mixtures:
- To determine the environmentally relevant concentrations of suggested endocrine disrupting chemicals in the aquatic environment (Phase 1; year 1).
- To assess whether the effects of mixtures of these chemicals are more potent on aquatic wildlife than suggested by the sum of individual effects (Phase 2A, B; second half of year 1 and year 2).
- To evaluate the applicability of neurotransmitter distribution and abundance as rapid indicators of adverse health effects in exposed aquatic wildlife (Phase 2B, 3; second half of year 2 and year 3).
To date, we have completed Phase 1, we are well underway with Phase 2A and 2B, and we have begun work on Phase 3 of the project. We have completed the analysis of six treated wastewater effluent samples from the Metropolitan Wastewater Treatment Plant (St. Paul, MN) and three samples from the Boulder Wastewater Treatment Plant (Boulder, CO), with an additional five Boulder samples currently being analyzed. Results indicate the presence of three major classes of biologically active compounds (natural hormones, pharmaceuticals, and alkylphenolic surfactants) in both effluents. Most compounds were found in higher concentrations in the Boulder treated effluent. Both effluents exhibited temporal variability, creating continuously changing complex mixtures.
We have also completed pilot exposure experiments with fathead minnows in the St. Cloud State University Aquatic Toxicology Laboratory and on site at the Boulder Wastewater Treatment Plant. Based on the results of these experiments, we have now completed the first of a series of laboratory exposure experiments using suggested endocrine disrupting compounds singularly and in mixture. To date we have completed exposures on diatoms and fathead minnows to 17ß-estradiol and ethynylestradiol at several concentrations. We have also completed dose-response exposures of diatoms to nonylphenol and fluoxetine. Our results suggest that diatoms are adversely affected by environmentally relevant concentrations of nonylphenol, but not estradiol. These results are consistent with a non receptor-mediated effect of nonylphenol that results in a reduced nutritional value of the diatoms for apical levels of the aquatic food chain.
Significance of Findings
The first reporting period has seen several important findings relevant to goals of the award and the U.S. Environmental Protection Agency’s mission:
- We determined that all major classes of biologically active compounds are present in the treated effluents of the Metropolitan and Boulder Wastewater Treatment Plants.
- We have determined that concentrations of these compounds vary over time, creating complex and ever-changing mixtures.
- We have determined that Boulder treated effluents affect exposed fathead minnows in a fashion that is consistent with endocrine disruption.
- We have determined that diatoms respond adversely to nonylphenol exposure at environmentally relevant concentrations, resulting in a reduced nutritional value of exposed diatoms for higher levels of the aquatic food chain.
In year 2 of this study, we plan to continue and complete diatom exposures to biologically active compounds singularly and in mixture. We also plan to expose daphnia cultures to the same compounds at similar concentrations to model the intermediate layer of a simplified aquatic food chain. We will complete fathead minnow exposures to biologically active compounds singularly and begin fathead minnow exposures to mixtures of biologically active compounds. Finally, we will use brain samples obtained from the exposed fishes to characterize the neural responses to exposure and optimize our analysis techniques.