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Methods to measure indicators of exposure in real-world aquatic environments
Citation:
LAZORCHAK, J. M., R. W. FLICK, A. D. BIALES, D. A. GORDON, D. C. BENCIC, G. T. ANKLEY, D. H. MILLER, A. Awan, AND L. ZINTEK. Methods to measure indicators of exposure in real-world aquatic environments. Presented at SETAC, Tampa, FL, November 16 - 20, 2008.
Impact/Purpose:
This presentation will overview some recent approaches for the detection and characterization of EDC exposures using several ongoing small scale studies. In addition, we discuss some experimental approaches aimed at linking real world exposure and effects due to EDC exposures.
Description:
Most of what is known about the implications of endocrine disrupting chemicals in the environment is somewhat anecdotal. There are numerous reports of gonadal histological abnormalities (Potomac, United Kingdom Rivers), alterations in sex ratios (Boulder Creek, Colorado) and high vitellogenin protein levels in fish below wastewater treatment plants. There has been some linear regression modeling describing the relationship between estrogens and relative fecundity linked to population models to predict trajectories of decreases in population size. However, there remains no clear and direct field-measured linkage between observed abnormalities and population level effects. In the case of the Potomac, community level measures such as indices of biotic integrity showed no relationships to ova-testis in smallmouth bass. One recent study in 2007 did show a collapse of fathead minnows, pearl dace and lake trout populations over a 5 year study in which a whole lake was dosed for 3 years with ethynylestradiol. Indicators were measured in this study from the molecular level to the whole animal level in order to link such measures to population effects. Only weight of evidence relationships could be drawn from this study, however, some of the molecular level indicators did show indication of estrogen exposure before the Catch Per Unit Effort (CPUE) fish collections showed significant reductions in population size. Understanding when and how exposures occur are critical factors that impact the ability to understand the potential impacts of EDCs.