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EVALUATION OF MINIMUM DATA REQUIREMENTS FOR ACUTE TOXICITY VALUE EXTRAPOLATION WITH AQUATIC ORGANISMS
Citation:
Buckler, D. R., F L. Mayer Jr., M. R. Ellersieck, AND A. Asfaw. EVALUATION OF MINIMUM DATA REQUIREMENTS FOR ACUTE TOXICITY VALUE EXTRAPOLATION WITH AQUATIC ORGANISMS. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-03/104, 2003.
Impact/Purpose:
The goals of this effort were to: 1) compile and organize an extensive body of acute toxicity data, 2) characterize the distribution of toxicant sensitivity across taxa and species, and 3) establish appropriate toxicity extrapolation factors based upon toxicological relations among species and chemicals.
Description:
Buckler, Denny R., Foster L. Mayer, Mark R. Ellersieck and Amha Asfaw. 2003. Evaluation of Minimum Data Requirements for Acute Toxicity Value Extrapolation with Aquatic Organisms. EPA/600/R-03/104. U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Gulf Ecology Division, Gulf Breeze, FL. 60 p.
Assessment of risk posed by an environmental contaminant to an aquatic community requires estimation of both its magnitude of occurrence (exposure) and its ability to cause harm (effects). Our ability to estimate effects is often hindered by limited toxicological information. As a result, resource managers and environmental regulators are often faced with the need to extrapolate across taxonomic groups in order to protect the more sensitive members of the aquatic community. The goals of this effort were to: 1) compile and organize an extensive body of acute toxicity data, 2) characterize the distribution of toxicant sensitivity across taxa and species, and 3) establish appropriate toxicity extrapolation factors based upon toxicological relations among species and chemicals. The results of this effort allow for better use of available information for predicting the sensitivity of untested species to environmental contaminants.
Three extensive databases containing acute toxicity information were obtained. The first was the combined acute toxicity database of the U.S. Geological Survey's Columbia Environmental Research Center and the U.S. EPA's Gulf Ecology Division. A second database was obtained from the U.S. EPA's Office of Pesticide Programs. The third database (EVISTRA, a component of the AQUIRE/ECOTOX database) was obtained from U.S. EPA's Office of Research and Development. In order to develop the most useful database for the purpose of evaluating toxicological relations across chemicals and taxa, it was necessary to standardize the information to be incorporated and establish a core data set. This was accomplished in a series of iterative steps. In general terms, data that were derived from studies that approximated the acute toxicity test conditions outlined by the American Society for Testing and Materials (2002) and/or the Committee on Methods for Toxicity Tests with Aquatic Organisms (1975) were retained, while other data were eliminated. This paring of information greatly reduced the number of data points retained, but served to eliminate variability that would have hindered discernment of toxicological relations.
As part of this project, a software program entitled "Ecological Risk Analysis" (ERA) was developed. The utility of this program is to assign sensitivity rankings (as percentile values) to species with known acute toxicity values for a given chemical and then predict an acute toxicity value for theoretical species with designated sensitivities. For this effort we chose to focus on estimating LC50 values for the theoretical 5th percentile most-sensitive species. The ERA program was used to establish initial estimates of 5th percentile values using the core data sets. Subsequently, various extrapolation and prediction methods were evaluated in terms of their ability to estimate comparable 5th percentile values for severely limited data sets.
While it is obviously desirable to have high quality acute toxicity values for as many species as possible for predicting toxicity values for sensitive members of the aquatic community, it is often necessary to make predictions for new or existing chemicals based upon limited data. The results indicate that the ERA program can be used with limited data sets to predict reasonable taxa-specific values for sensitive organisms. Further, if simple extrapolation from data on a single species must be used, the most satisfactory results were obtained with rainbow trout, bluegill, or scud.
Final report of EPA Project No. DW-14-93900201-1 submitted to the U.S. Environmental Protection Agency Office of Pesticide Programs, April 1, 2003. Assigned EPA/600/R-03/014 dated July 2003.