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Research Programs
Endocrine Disruptors Effects Research
Endocrine Disruptors
Effects Research
Wildlife and Extrapolation Studies
Few details are known about how the natural hormonal profiles and fertility rates of wildlife species change over time. An example of how this lack of information can hinder EPA's ability to assess whether EDC effects are occurring arose in a study in which differences in sex steroids in fish collected from several field locations were reported, but it was unclear whether these differences were due to the presence of a contaminant at some of the sites or whether the differences were due to temporal variations in the fishes' reproductive cycles. A goal of EPA research on EDCs is to fill this data gap for a variety of species using routine monitoring experiments studies to determine the baseline endocrine status in wildlife populations and their laboratory surrogates.
EPA scientists are also working to form a fuller understanding of the similarities and differences in endocrine system functioning between species. Advances in comparative endocrinology and toxicology and in scientists' understanding of the biochemical pathways through which a substance induces its effects (known as a chemical's "mechanism of action") will reduce uncertainties in extrapolations between species. Studies to advance this type of knowledge are important for extrapolations between species and for developing predictive models because it is not practical to study every type of organism. Additionally, EPA is working to improve the knowledge base required for extrapolating results of effects studies conducted at the sub-organism level to the level of organisms and populations.
