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Bioaccumulation and toxicity of the flame retardant TBPH or the polychlorinated biphenyl PCB153 during dietary exposure in mummichog (Fundulus heteroclitus)
Citation:
Clark, B., A. Bertrand, I. Kirby, Saro Jayaraman, M. La Guardia, D. Champlin, AND D. Nacci. Bioaccumulation and toxicity of the flame retardant TBPH or the polychlorinated biphenyl PCB153 during dietary exposure in mummichog (Fundulus heteroclitus). Society of Environmental Toxicology and Chemistry (SETAC) North America 37th Annual Meeting, Orlando, FL, November 06 - 10, 2016.
Impact/Purpose:
This product describes experimental studies that contribute to our understanding of the ecological risks associated with chronic contaminant exposures to wildlife populations. Results of these studies demonstrate the value of molecular tools to diagnose and predict effects of chemical stressors and characterize the mechanisms and costs of toxic and compensatory responses to chemical stressors by wild populations. General impacts from this contribution include improved understanding by managers and scientists of links between human activities, natural dynamics, ecological stressors and ecosystem condition.
Description:
The use of polybrominated diphenyl ethers as flame retardants in consumer products has been scrutinized increasingly due to their environmental persistence and potential toxicity; however, alternative replacement flame retardants may have similar drawbacks. The alternative brominated flame retardant bis(2-ethylhexyl)-2,3,4,5-tetrabromophthalate (TBPH) is a component of several commercial flame retardants, including Firemaster® 550, Firemaster® BZ-54 and DP-45. Here we investigate the bioaccumulation, bioenergetics and other adverse outcomes pathways (AOPs) predicted for dietary exposure to a carrier control, two levels of TBPH, or 2,2',4,4',5,5'-hexachlorobiphenyl (PCB153, a well-studied compound acting as a positive control for some aspects of the study). The TBPH concentrations chosen were at or well above the environmental concentrations documented in the literature, but similar to those causing toxicity in a previous study. Our experimental model is a small estuarine fish, the mummichog (Fundulus heteroclitus), exposed as individually tagged fish held in small groups (2 male, 2 female) in replicate tanks and fed contaminated food from day 0-28, followed by uncontaminated food from day 29-42. Throughout the experiment, individual growth was measured weekly, and at various time points, fish from replicate tanks were sacrificed, measured and dissected. To support putative AOPs, samples were obtained for analysis of hormone levels and transcriptomic responses to the exposures. After 28 days, the average sizes of fish in comparison to controls was larger in the PCB153 treatment group, and smaller in the treatment fed the high concentration of TBPH. These data will be used as input for a Dynamic Energy Budget model (currently under development for this species) to project effects throughout the life cycle. Rates of bioaccumulation and depuration determined during the study will be compared to predictions from standard bioaccumulation models, such as BASS. As expected, PCB153 was highly bioaccumulative and persistent; in contrast, a much smaller percentage of the provided TBPH was measured in fish. Coupling these growth and bioaccumulation data with ongoing transcriptomic analyses will improve our understanding of the bioaccumulation and adverse outcomes from dietary exposure to TBPH and PCB153. Ultimately, this work will support the application of ecological models to extrapolate effects of chemical exposures across species and chemical classes.