| A wide variety of both naturally occurring and man-made chemicals have the ability to mimic hormones. Exposure to these chemicals during critical periods of an organism's development may disrupt the formation of a fully functioning endocrine system. Assessing the effects of exposure to these endocrine disrupting chemicals (ECDs) is particularly difficult since the time of exposure is often temporally removed from the time the effects become evident. In addition, since the endocrine system has well developed homeostatic mechanisms, these effects may be relatively subtle, although they may endanger both individuals and populations.; In order to identify chemicals with EDC potential, a screening protocol was developed. This protocol utilizes terrapin turtles as a model, since gender in this organism is determined primarily by the temperature at which eggs are incubated. Thus, development of female characteristics by embryos incubated at male producing temperatures due to exposure to a chemical indicates that chemical is estrogenic. Using this screen, the hydroxylated form of PCB 30 (2′,4′,6′-trichloro-4-biphenylol) was shown to be estrogenic.; Standard toxicological tests are ineffective in determining if animals have been exposed to EDCs. A wide variety of potential assay endpoints were investigated to determine their efficacy in identifying EDC exposure. This work was done using the Japanese quail as a model. Japanese quail develop rapidly, allowing assessment of effects in mature animals of embryonic exposure and making multigenerational tests possible. Japanese quail also exhibit well characterized stereotypic mating behaviors, so changes in these behaviors due to chemical exposure are significant. Of the many endpoints tested, levels of neurotransmitters seemed responsive to ECD. However, it was the behavior of the adult birds that was most revealing of ECD history. Finally, criteria for evaluating the relevance of EDC endpoints to wildlife managers is discussed. |
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