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An investigation into the extent and bilogcal impacts of endocrine disrupting chemicals (EDCs) in a highly effluent-dominated river in New England
Citation:
MCDONALD, D., K. KIPP, B. HOSKINS, T. FABER, A. BATT, M. MILLS, L. ZINTEK, J. M. LAZORCHAK, H. Haring, AND S. Nakayama. An investigation into the extent and bilogcal impacts of endocrine disrupting chemicals (EDCs) in a highly effluent-dominated river in New England. Presented at SETAC, Boston, MA, November 13 - 17, 2011.
Impact/Purpose:
A great deal of uncertainty exists regarding the extent to which humans and wildlife are exposed to chemical stressors in aquatic resources. Scientific literature is replete with studies of xenobiotics in surface waters, including a recent national USGS survey of endocrine disrupting chemicals; however, biological significance of these chemical data is in question since chemical bioavailability is largely unknown and biological events may be induced by undetected chemicals and varying ecological conditions (i.e., total nitrogen and phosphorus). Whole effluent toxicity data exist, but do not answer specific exposure questions that may support detailed ecological risk assessments. Interpretation of data arising from exposure to complex chemical mixtures is even more problematic. A solution to these problems is development of sensitive and specific cellular indicators of exposure in aquatic organisms. The potential for development is enhanced by emergent resources in molecular biology and associated technologies, most notably DNA microarrays consisting of transcriptionally relevant nucleic acid sequences that can be used to detect altered gene expression in cells, tissues and various life stages of organisms exposed to chemical and natural stressors. Ecological investigation in the present Task have been partitioned into three focal research areas: (1) Core Computational Toxicology research, (2) Ecological research and (3) Molecular Diagnostics and endocrine disrupting compounds. Three areas of core and applied research will be consequential on development of molecular indicators diagnostic for exposure to specific xenobiotic, natural stressors, and complex mixtures thereof, in freshwater fish and invertebrates. Research is focused on Agency’s long-established aquatic toxicological organism, the fathead minnow (Pimephales promelas). Although numerous molecular biological approaches are exploited, foremost methods leading to development of molecular indicators are assembly and manufacture of DNA microarrays containing transcriptionally relevant gene sequences of fathead minnow, and the detection of novel or differentially expressed proteins by means of 2-D polyacrylamide gel electrophoresis followed by mass spectrometry. An extensive effort in 'gene discovery' research with the fathead minnow has been the primary emphasis of respective research areas, since high-throughput genome sequencing efforts-such as those in human and mouse-have not been directed toward organisms used in aquatic toxicity testing such as fathead minnows. Gene discovery research is fundamental to identified research areas, and is expected to be augmented by high-throughput cDNA sequencing data arising through a collaborative effort with the Dept. of Energy, Joint Genome Institute. Also, proteins induced to differential expression by chemical exposure will be used in ‘reverse genetics’ approach wherein knowledge of protein sequence will make possible the investigation of gene function and associated mechanistic biology. Following development and validation, fathead minnow microarrays, along with critical indicators identified by expression proteomics, will enable extensive molecular profiling studies, the hypotheses of which are that unique patterns of gene expression will be detected in targeted tissues of fathead minnows exposed to individual chemical stressors. Identification of unique, differentially expressed genes will then provide the basis for stressor-specific, quantitative molecular indicators, theory and methods that can be readily transferred to investigators within USEPA Regions, Tribes and states.
Description:
The Assabet River in central Massachusetts is a heavily effluent-dominated river and during low-flow conditions, is composed almost entirely of waterwater effluent (i.e., up to 95%). The U.S EPA Regional New England Laboratory and the U.S. EPA Office of Research and Development Cincinnati Laboratory have been conducting a two-year study to investigate endocrine disrupting chemicals (EDCs) in the effluents and their potential impact on fish in the river. During the first year of the study, effluents from four wastewater treatment plants were anlayzed for a suite of EDCs, steroid compounds, perfluorinated chemicals (PFCs) and other pharmaceuticals and personal care products (PPCPs). Forage fish were collected from the river and anlayzed for indicators of EDC exposure, including histopathology and vitellogenin (i.e., egg yolk protein) induction in male fish. Larval whole effluent toxicity exposure tests were conducted using effluents from the plants. Of the 54 pharmaceutical analytes, 29 were found across all four effluents, with six of those having concentrations near l ug/L. For the eight steroids measured, one effluent had a concentration of ethinylestradiol at concentrations known to cause effects on fathead minnow fecundity. Two plants had PFCs (PFOS/PFOA) at levels near the Minnesota Pollution Control Agency Aquatic Life Criteria. Nonyl phenols were found at concentrations of at least 5 ug/L in all effluents.