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TOXICITY APPROACHES TO ASSESSING MINING IMPACTS AND MINE WASTE TREATMENT EFFECTIVENESS
Citation:
Lazorchak, J M., M E. Smith, E R. Bates, AND R C. Wilmoth. TOXICITY APPROACHES TO ASSESSING MINING IMPACTS AND MINE WASTE TREATMENT EFFECTIVENESS. Presented at Hardrock Mining Conference, Westminster, CO, May 7-9, 2002.
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 USEPA Office of Research and Development's National Exposure Research Laboratory and National Risk Management Research Laboratory have been evaluating the impact of mining sites on receiving streams and the effectiveness of waste treatment technologies in removing toxicity for the past six years. The effectiveness of site assessments and minewaste treatment technologies in reducing toxicity was assessed using toxicity tests on the Summitville mine site, Clear Creek and North Fork of Clear Creek, Burleigh Tunnel and Big Five Tunnel in Colorado and Calliope Mine, Crystal Mine, Lily Orphan Boy Mine, Peerless Mine and Sure Thing Mine in Montana. Water samples were collected from the stream sites or mining sites and shipped to the USEPA Aquatic Research Facility in Cincinnati, Ohio. A series of acute aquatic toxicity tests with Pimephales promelas, the fathead minnow, and Ceriodaphnia dubia, a freshwater invertebrate, were conducted on these samples. In addition to these tests, a 7-day growth test using rainbow trout, Oncorhynchus mykiss, was conducted on Summittville minewaste samples. The purpose of these tests was to establish the level of toxicity for the discharge from the different mine sites and to evaluate the effectiveness of different treatment processes used at these sites. The results from the tests on the effluents from treatment technologies used at the Sure Thing and Lily Orphan Boy mine sites indicate that there is a significant reduction in toxicity. For the Sure Thing Mine treated effluent, C. dubia survival LC50 value was increased by 670 fold and the No Observable Acute Effect Level (NOAEL) by 640 fold. The P. promelas LC50 value was increased by 24 fold and the NOAEL value by 20 fold. For the Lily Orphan Boy treated effluent the C. dubia LC50 value increased by 160 fold and the NOAEL by 320 fold. The P. promelas LC50 value increased by 21 fold and the NOAEL by 40 fold. For the Summittville Mine Treatment System, treated mine discharge samples displayed reduced toxicity of approximately 7-8 fold for C. dubia, 10 fold for rainbow trout, and about 5 fold for the fathead minnow as compared to untreated mine waste. However, in order to remove all the acute toxicity from the mine discharge, the concentration of metals from both treatments have to be reduced by a 1000 fold for C. dubia survival, or a 100 or 50 fold for rainbow trout, and fathead minnow survival, respectively.