Citation:

BIALES, A. D., B. R. JOHNSON, J. E. FLOTEMERSCH, E. EMERY, AND J. M. LAZORCHAK. ASSESSING ENDOCRINE-DISRUPTING CHEMICAL EXPOSURE IN INDIGENOUS AQUATIC POPULATIONS IN THE OHIO RIVER. Presented at 2005 EPA Science Form, Washington, DC, May 16 - 18, 2005.

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 of 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 exposu

Description:

The NERL has launched a collaborative study with the ORSANCO to determine the degree of ecologically relevant endocrine-disrupting chemical (EDC) exposure in the New Cumberland Pool of the Ohio River under the Environmental Monitoring and Assessment Program - Great Rivers Project (EMAP-GRE). EDCs are common to oral contraceptives and are often present at relatively high levels in sewage effluents from metropolitan areas as well as runoffs from cattle farms. There are increasing examples of male fish displaying female sex characteristics in the waterways of the United States and Europe. EDCs have been shown to affect multiple aspects of fish biology including fecundity, mortality, and development. These biological endpoints require large-scale morphological or behavioral changes and constant long-term exposure. Therefore, before these indicators are manifest at measurable levels, indigenous populations have already undergone significant environmental stress. In contrast, changes in gene expression are often the initial and direct response of biological systems to EDCs and other environmentally relevant toxicants and are measurable at exceedingly low levels. Gene expression is becoming a commonly used diagnostic tool in human health for cancer research and is now gaining acceptance in the ecological world. The most well established genetic indicator of EDC exposure in aquatic systems is the egg precursor protein vitellogenin (Vg), expressed in reproductive females and quiescent in males. The NERL Cincinnati recently established a sensitive experimental system capable of reproducibly measuring changes in Vg mRNA abundance in response to a variety of estrogenic, hormonal EDCs. To field-test our experimental system, ORSANCO will collect samples of two indigenous fish species, the smallmouth bass and the smallmouth buffalo. This project will validate the ecological relevance of aberrant male Vg expression in wild populations by integrating other more established indicators of ecological disruption also surveyed under the EMAP Great Rivers Project. We will critically evaluate indicators of ecological disturbances at different spatial scales ranging from the individual through the landscape level to determine the most appropriate indices of environmental health. Finally, we will gain important information as to the extent of EDC exposure in aquatic ecosystems of the New Cumberland Pool of the Ohio River.

Record Details: