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Comparative Sub-lethal Effects of Brominated Flame Retardants Following Simulated Maternal Transfer and Dietary Exposure in Two Species of TurtlesEPA Grant Number: F07D40791
Title: Comparative Sub-lethal Effects of Brominated Flame Retardants Following Simulated Maternal Transfer and Dietary Exposure in Two Species of Turtles
Investigators: Eisenreich, Karen M.
Institution: University of Maryland Center for Environmental Science
EPA Project Officer: Manty, Dale
Project Period: August 29, 2007 through August 29, 2010
RFA: STAR Graduate Fellowships (2007) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Endocrine Disruptors
The overall objective of this study is to quantify effects of environmentally realistic concentrations of brominated diphenyl ethers (BDEs) on embryonic and juvenile traits of two species of turtles, the common snapping turtle and red-eared slider, which may differentially metabolize and respond to BDE exposure. BDEs are a group of synthetic compounds employed widely in consumer products and industry as flame retardants. Recent identification of BDEs in environmental matrices and human tissues has spurred concern worldwide in scientific and regulatory communities. A lack of information on BDE metabolism and effects on long-lived species presents a critical data gap hindering understanding of the impacts of chronic accumulation and effects on natural systems. Thus, development of models that represent the types of processes that occur under natural exposure regimes is critical for evaluating ecological implications of BDEs. Vertebrates having long life spans, delayed maturation, and high trophic status may be particularly at risk to the effects of BDEs due to their propensity to accumulate and transfer persistent lipophilic contaminants to offspring. Turtles, in particular, possess these traits and, while they are known to accumulate and transfer BDEs to eggs, resultant effects on offspring health and fitness are unknown.
Using one year-long, factorial experiments, the relative effects of maternal (embryonic) and environmental (food borne) exposures on endocrinological, developmental, metabolic, and behavioral traits will be determined. These endpoints address purported thyrogenic effects of BDEs which may alter neurological, developmental and metabolic processes. As BDEs may also affect estrogen-dependent pathways, alterations in sexual differentiation and gonadal development will also be quantified. To simulate maternal transfer, BDEs will be dissolved in dimethyl sulfoxide and topically applied to eggs in concentrations and volumes previously determined to effectively deliver target concentrations to the embryos. Subsequently, hatchlings will be exposed to BDEs through their diet with BDE-enriched food. Thyroid hormone concentrations, morphological development, metabolic efficiency, and several behavioral endpoints will be quantified from hatching through one year of age.
The project will provide a comprehensive examination of the effects of common BDEs based upon a suite of developmental, physiological, and behavioral traits. Thus, stronger inferences regarding the multiple mechanisms that may be altered by BDEs and the overall effects on offspring performance and quality in long-lived species can be made. By simulating maternal transfer of BDEs, insights will be gained regarding the perhaps subtle effects experienced during the vulnerable initial growth phase. The dietary exposure will also provide information on the potential effects of environmental exposure during the period of rapid development and growth that occurs during the first year post hatching. The study will quantify the relative influences of exposures from maternal and environmental sources and the interactive effects of these exposure regimes, the latter providing information on possible latent or cumulative effects that would not be captured in typical, short duration studies. The project will benefit regulators and researchers in assessing environmental risks and setting future research priorities for these contaminants of emerging global concern.