Biomarkers and Effects of Estrogenic Environmental Chemicals in Frogs

EPA Grant Number: R823139
Title: Biomarkers and Effects of Estrogenic Environmental Chemicals in Frogs
Investigators: Ramsdell, Howard S.
Institution: Colorado State University
EPA Project Officer: Hahn, Intaek
Project Period: October 1, 1995 through September 30, 1997
Project Amount: $145,360
RFA: Exploratory Research - Environmental Biology (1995) RFA Text |  Recipients Lists
Research Category: Biology/Life Sciences , Human Health , Aquatic Ecosystems


Environmental changes are part of the cause of amphibian population declines. Little is known about the extent to which chemical contaminants contribute to losses of amphibians. This project seeks to improve the understanding of the effects of estrogenic environmental contaminants on amphibians. The goals of this project are to: 1) determine the effects of environmental contaminants with known endocrine-disrupting activity on larval development and metamorphosis in an amphibian, and 2) develop and evaluate biomarkers of these effects.

The common laboratory frog Xenopus laevis will be used as a model in most of the experiments, being readily available and easily cultured. Larvae will be exposed in a continuous flow system to serial dilutions of the test agents through metamorphosis and for a brief period of juvenile development. Morphological and histological evaluations will be used to assess chemical impacts on sexual development. Samples will be collected for analysis of vitellogenin and other potential biomarkers of altered endocrine function. A species native to the U.S., Rana pipiens, will then be evaluated for effects of endocrine-disrupting chemicals based upon the results with X. laevis.

These studies will determine if frogs are subject to adverse effects of environmental estrogens at concentrations that are below those that cause overt toxicity. If sexual development is altered by larval exposure, post-metamorphic reproductive capability may be impaired, with potentially significant implications for amphibian populations. The development of useful biomarkers of exposure and effects of estrogenic chemicals would provide useful tools for the evaluation of the impacts of such chemicals on free-living amphibians.

Supplemental Keywords:

RFA, Health, Scientific Discipline, Environmental Chemistry, Endocrine Disruptors - Environmental Exposure & Risk, endocrine disruptors, Biochemistry, Children's Health, Biology, Endocrine Disruptors - Human Health, bioindicator, morphological biomarkers, biomarkers, frogs, endocrine disrupting chemicals, sexual development, chemical mixtures, developmental biology, vitellogenin, animal models, chemical interference

Progress and Final Reports:

  • 1996
  • Final