Citation:

SMITH, MARK E., H. J. HARING, J. BERNINGER, M. WRATSCHKO, G. AHLERS, A. PARKS, AND J. M. LAZORCHAK. A SEDIMENT TOXICITY EVALUATION OF THREE LARGE RIVER SYSTEMS. Presented at Society of Environmental Toxicology and Chemistry, Montreal, QC, CANADA, November 05 - 09, 2006.

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:

Sediment toxicity samples were collected from selected sites on the Ohio River, Missouri River and upper Mississippi River as part of the 2004 and 2005 Environmental Monitoring and Assessment Program-Great Rivers Ecosystems Study (EMAP-GRE). Samples were collected by compositing sediment from 10 equally spaced transects across a 500 meter segment of river. The sediment samples were evaluated for toxicity using a Hyalella azteca 7-day lethality and growth, static-renewal test method. For 2004, a total of 165 samples were collected. Of these, 27 were acutely toxic while 21 exhibited a growth effect. For 2005, a total of 221 sediment samples were collected. Of these, 29 were acutely toxic while 85 exhibited a growth effect. Sixteen percent of the samples were found to be acutely toxic in 2004 and 13% in 2005. This is about twice the average of toxic samples found in previous studies using the same site selection criteria in the Mid-Atlantic Highlands and Rocky Mountain West. Twenty-eight sites were sampled in both 2004 and 2005. For these sites, the sediment test results (either acute lethality or no lethality) remained the same over both years for 24 sites. During 2004, 24 sites were sampled twice, 18 sites showed no change in the test results for either acute lethality or no lethality. In 2005, 22 sites were sampled twice, 17 showed no change in the test result for either acute lethality or no lethality. The samples from 2004 and 2005 that were classified as toxic were analyzed for 6-PBDE congeners, 20 PCB congeners, and 22 chlorinated pesticides. Of the samples analyzed, PCB¿s were detected in 7 (2004) and 5 (2005). Chlorinated pesticides were detected in 8 (2004) and 5 (2005). PBDE's were not detected in the 2004 samples but were detected in four 2005 samples.

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