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PresentationsBiocides and Antimicrobials2015

Evaluating the Relative Sensitivity of Endpoints Generated During Midge Life-Cycle Sediment Toxicity Tests

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PRESENTATION ID: 606

PRESENTATION DATE: Thursday, November 5, 2015 at 8:20AM

LOCATION: Ballroom D

ABSTRACT:

Midges (Diptera: Chironomidae) are used as model test organisms for evaluating the potential toxicity of chemicals sorbed to sediments. The guidance document “Methods for Measuring the Toxicity and Bioaccumulation of Sediment-associated Contaminants with Freshwater Invertebrates” (EPA 600/R-99/064) released in March 2000 details procedures for conducting life-cycle tests with midges. There are ongoing efforts to revise certain aspects of the guidance document and members of the SETAC Midge Chronic Testing Working Group are providing technical insight with the aim of further advancing the test method. One area of potential revision pertains to the evaluation of appropriate test endpoints. Currently, lethality-based endpoints for the life-cycle test include larval, pupal and adult survival, while sublethal endpoints include larval growth, adult emergence (total/percent, cumulative rate, time to first emergence, and time to death), and reproduction (sex ratio, time to oviposition, mean eggs/female, egg cases/treatment, and egg hatchability). High variability in control response and redundancy of information gained from similar observations prompted scientific inquiry concerning the utility and/or necessity of some endpoints for defining biological effect thresholds. Streamlining the number of measured endpoints could improve the efficiency of the test method and also provide researchers with greater confidence that observed effects are indeed related to contaminant exposure and not manifested merely as a result of natural biological variability. Members of the Crop Life America Sediment Subcommittee team compiled midge toxicity data from studies completed with agrochemicals for retrospective analysis to gain greater understanding of the relative sensitivity of endpoints from the midge life-cycle study. The purpose of this presentation is to briefly review findings of the aforementioned effort and discuss implications for future midge life-cycle testing efforts.

Theodore Valenti, Syngenta; Michael Bradley, Smithers Viscient; Jennifer Gates, Mark Cafarella, Waterborne Environmental; Jeffrey Giddings, Compliance Services International; Hank Krueger, Wildlife International; Sean McGee, Bayer CropScience LP; Alan Samel, DuPont Crop Protection; Bibek Sharma, FMC Corp Global Regulatory Sciences; Jane Staveley, Exponent; Jiafan Wang, BASF Agriculture Solutions. “Evaluating the Relative Sensitivity of Endpoints Generated During Midge Life-Cycle Sediment Toxicity Tests”. SETAC Salt Lake City November 2015.