PORTLAND, Oregon --
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TESTING VARIABILITY RESEARCH ON BIOACCUMULATION TESTS
Dr. Moore will be presenting results of a recent round robin study of standard dredged material bioaccumulation tests designed to quantify variability and better inform management decisions. Based on study results, exposure variability (i.e., results across labs conducting bioaccumulation tests) ranged from 1.4X to 2.0X, while analytical variability (i.e., results across analytical labs measuring tissue concentrations) ranged from 1.4X to 2.5X. These results will be discussed along with potential implications for test interpretation.
Background: Dredged material bioaccumulation tests are a critical component of tier III dredging evaluations utilized under both the CWA and MPRSA. These tests are designed to enhance the ability to detect statistical differences in tissue residues in organisms exposed to dredged and reference material for purposes of establishing how the material maybe managed (e.g., open water disposal, placement in a confined disposal facility, etc.). However, simple statistical differences can in some instances be an artifact of the test as opposed to an accurate reflection of meaningful differences in contaminant uptake. Simple statistical differences often do not equate to meaningful, biologically relevant ones, therefore it is important to understand the role of variability associated with experimental design (exposure and analysis) and provide guidance to ensure appropriate expenditure of resources for additional analysis and interpretation only in those instances where a meaningful, biologically relevant, difference has been established. Understanding the variance associated with bioassay test system (both within test and analytical) is critical for accurately assessing potential bioaccumulation risks of dredged material. Although many labs have demonstrated capability to conduct bioassays using recommended species and many chemistry labs have demonstrated capability to the quantify concentrations in tissue samples, the inter-laboratory variability associated with the conducting the bioassay and quantifying body residues for those species has never been determined. Understanding this variability is critical to establishing when differences in tissue residues of reference and project material exposed organisms warrant further, more expensive evaluation to ascertain the appropriate disposition of the material for purposes of placement/management.
Dr. Moore is a Senior Research Biologist with the US Army Corps of Engineers Research and Development Center in Vicksburg, MS. He currently leads the risk focus area for the USACE Dredging Operation and Environmental Research Program where he helped develop both the ocean and inland testing manuals for the assessment of dredged materials and co-developed the Environmental Residue Effects Database for the assessment of bio-accumulated tissue residues. Dr. Moore currently serves as the director of the ERDC Center for Emerging Contaminants of Concern and as the USACE representative to the London Convention for the Disposal of Waste at Sea.