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Evaluation and Standardization of a Whole Effluent Short Term Growth Toxicity Test Method using Daphnia magna
Citation:
Lazorchak, J., T. Norberg-King, A. Kascak, W. Thoeny, C. Flinders, A. Johnson, L. Glimsdal, AND M. Griffith. Evaluation and Standardization of a Whole Effluent Short Term Growth Toxicity Test Method using Daphnia magna. 2021 SETAC North America Annual Meeting, Virtual, November 14 - 18, 2021.
Impact/Purpose:
This presentation will cover the research being done on a D magna short term growth WET method to be used by the program office and regions.
Description:
In 2009, US EPA’s Office of Research and Development (ORD) published a paper titled, Development and Validation of a Daphnia magna Four-Day Survival and Growth Test Method. The test results were compared to performance criteria and results from 7-d survival and reproduction tests with Ceriodaphnia dubia, to assess the level of comparability of the two methods. Results from tests using the 4-d D. magna survival and growth method showed that this method produced consistent results with various reference toxicant materials and provided data that were both reproducible and useful for detecting potential toxicity in aquatic environments. Since that publication, there has been an increased interest in using the D. magna method in Whole Effluent Toxicity (WET) tests. In 2020, ORD began re-evaluating the method in a bi-laboratory approach at US EPA laboratories in Cincinnati, OH and Duluth, MN as well as a collaboration with National Council for Air and Stream Improvement (NCASI). As part of the first phase of testing, ORD is currently evaluating various test conditions such as test duration (4-d vs 5-d), number of treatment replicates (n=4, 5, or 6 replicates/treatment) in a five concentration test, test food types and levels, and the general culture conditions. Various test and culture conditions may contribute to test variability and the ability to meet the original performance criteria. In our studies, we are using the performance criteria of 80% control survival with a mean final dry weight of ≥10X greater than mean initial test organism dry weight. Preliminary results indicate a 4-d procedure is reproducible in within-lab testing with KCl, with test evaluation at other laboratories currently underway. Demonstration of an acceptable level of intra- and inter-laboratory variability is required for the acceptability and approval of a WET test method. A second phase will involve using the test conditions determined to be reproducible in Phase 1 to examine D. magna survival and growth response to a larger suite of reference toxicants (KCl, ZnSO4, NH4Cl, phenol and bifenthrin) and the consistency of responses over multiple tests (n=3 tests/toxicant) and at least five effluents. This presentation will highlight the latest progress of Phase 1 outcomes.
