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THE PRESENCE OF ESTROGENIC AND ANDROGENIC SUBSTANCES IN EFFLUENTS FROM CONCENTRATED ANIMAL FEEDING OPERATIONS
Citation:
Lazorchak, J M. AND M E. Smith. THE PRESENCE OF ESTROGENIC AND ANDROGENIC SUBSTANCES IN EFFLUENTS FROM CONCENTRATED ANIMAL FEEDING OPERATIONS. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-04/172, 2004.
Impact/Purpose:
The indeterminate condition of exposure indicator research stands to change markedly with the ability to connect molecular biological technologies with cellular or tissue effects and outcomes. Three focal areas of ecological research aim to develop a sequence of approaches where "the earliest recognizable signatures of exposure" (i.e., unique patterns of up- and down-regulated genes and proteins) are identified for numerous stressors, demonstrable in case studies and incorporated into Agency, State and Regional studies supported by EMAP and other programs. Area 1, Computational Toxicology Research: Exposure assessment has historically been based on use of chemical analysis data to generate exposure models. While biological activity of chemicals has been recognized to be important for exposure risk assessments, measurement of such activity has been limited to whole organism toxicity tests. Use of molecular approaches will: improve extrapolation between components of source-to-outcome continuum (source , exposure , dose , effect , outcome). Using a systems modeling approach, gene and protein expression data, in small fish models (fathead minnow and zebrafish), will be integrated with metabolomic and histopathological data. This will assist in prediction of environmental transformation and chemical effects based on structural characteristics, and enhance quantitative risk assessments, including areas of uncertainty such as a basis for extrapolation of effects of endocrine disrupting chemicals, interspecies extrapolation, complex chemical mixtures and dose-response assessment. Area 2, Ecological Research-Environmental Diagnostics: Development of molecular diagnostic indicators contributes to several of the GPRA Diagnostic Research Goals. Methods will employ DNA microarray technology and expression proteomics, focusing on species of relevance to aquatic ecosystem risk assessment. Significantly, these diagnostic indicators will open the door to understanding subcellular interactions resulting from exposure to complex chemical mixtures; define relationship between genetic disposition of populations and degree/specificity of stressor-specific gene transcriptional response in aquatic organisms (fish and invertebrates); identify chemical mixture induced transcriptional "patterns" using microarrays and hyperspectral scanning - via collaboration with DOE Sandia National Labs; apply molecular indicators to watershed level stressor study, including pilot studies with targeted pesticides and toxins indicators; develop molecular indicators of exposure for invertebrates (Daphnia, Lumbriculus, Chironomus). Area 3, Exposure Research in Endocrine Disruptors: Subobjective 1: Develop exposure methods, measurement protocols, and models for assessment of risk management practices of endocrine disrupting compounds. As risk management approaches are identified and developed, there will be a need to identify, adapt and develop bioassay screening tools and other analytical methods to assess their efficacy. Measurements research will be performed to define management needs. This effort will entail cross-lab participation from NRMRL, NERL and NHEERL. Subobjective 2: Determine extent of environmental and human exposures to EDCs, characterize sources and factors influencing these exposures, develop and evaluate risk management strategies to reduce exposures. In order to develop effective risk management strategies, it is important to understand the extent of exposures to endocrine disrupting compounds and factors influencing source-to-exposure-to-dose relationships; apply molecular indicators of exposure to estrogenic compounds in selected wastewater treatment plants located in ten USEPA Regions; identify differential gene expression following exposure of fathead minnows to environmental androgens and androgen-like compounds; apply molecular indicators of exposure to estrogenic and androgenic compounds present in CAFO studies - linkage to chemistry
Description:
In February 2003 the U.S.EPA published a final rule on National Polllutant Discharge Elimination System Permit Regulation and Effluent Limitation Guidelines and Standards for Concentrated Animal Feeding Operations (CAFOs). Manure and wastewater from CAFOs have the potential to contribute pollutants such as nitrogen and phosphorus, organic matter, sediments, pathogens, heavy metals, hormones, antibiotics and ammonia to the environment. Excess nutrients in water (e.g., nitrogen and phosphorus) can result in or contribute to low levels of dissolved oxygen (anoxia), eutrophication and toxic algal blooms. The CAFO rule mainly covers the control of nutrients and bacterial contamination. This report investigated the potential ecological effects of hormonally-active substances associated with discharges from cattle feeding operations. Revalor S7 implants, which contain both trenbolone acetate and 17B-estradiol were used on the 6000+ cattle that were housed at the study CAFO facility. Trenbolone acetate is a synthetic anabolic steroid that is widely used in beef production in the U.S. Metabolites of trenbolone acetate include the stereoisomers 17a- and 17B-trenbolone, both of which are stable in animal wastes and are relatively potent androgens in reproduction assays with the fathead minnow, laboratory rat, and other species. The purpose of this study was to evaluate the potential of a fathead minnow vitellogenin gene expression assay as an indicator of androgenic substances like 17a- and 17B-trenbolone in a beef feedlot discharge, and in river water upstream and downstream from the discharge. Our objective was to see if sexually mature female fathead minnows would show reduced levels of vitellogenin gene expression when exposed to androgens. Samples were collected on three different occasions during 2002 and 2003. No consistent changes in vitellogenin gene expression were detected in female fathead minnows exposed to samples collected from a CAFO drain or downstream stream samples that had detectable concentrations of trenbolone shown in laboratory studies to cause effects on reproduction.