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Extramural Research

Validation of an Amphibian Lifecycle Test Method for Monitoring Endocrine Disruption

EPA Contract Number: EPD04054
Title: Validation of an Amphibian Lifecycle Test Method for Monitoring Endocrine Disruption
Investigators: Fort, Douglas J.
Small Business: Fort Environmental Laboratories Inc.
EPA Contact: Manager, SBIR Program
Phase: II
Project Period: April 1, 2004 through June 30, 2005
Project Amount: $225,000
RFA: Small Business Innovation Research (SBIR) - Phase II (2004)
Research Category: Small Business Innovation Research (SBIR) , Ecological Indicators/Assessment/Restoration , SBIR - Monitoring

Description:

The Phase I study resulted in the development of an assay that tests substances that have the capacity to disturb reproductive and developmental processes during the lifecycle of a vertebrate animal by interfering with the endocrine system. The primary goal of this Phase II research project is to standardize, validate, and commercialize an amphibian lifecycle model using Xenopus as a system for the evaluation of endocrine-disrupting chemicals (EDCs) found in the workplace or in the environment. Specifically, Fort Environmental Laboratories, Inc., standardized and evaluated the use of X. tropicalis as a model system to evaluate the effect of EDCs on various aspects of the amphibian lifecycle by conducting studies with a series of known mammalian EDCs and chemicals with unknown activity. 17ß-estradiol (E2), androstene dione, and methoxychlor were used to develop and standardize the model. Results from these studies were used to generate a final study protocol from which a Guidance Document ultimately will be prepared following Phase II interlaboratory validation studies.

Results from Phase I strongly indicated that chronic exposure to E2 slightly delayed development, had a marginal affect on the normalcy of early larval development, dramatically skewed sex ratios toward the female gender, induced gonadal malformations that included some intersexual development at low test concentrations, and induced liver abnormalities. Furthermore, chronic E2 exposure impaired both female and male reproductive fitness. Chronic exposure to E2 decreased breeding success in both sexes, decreased fertilization in exposed females, and decreased embryo-larval viability in the F1 progeny.

Chronic exposure to androstene dione dramatically skewed sex ratios toward the male gender, induced gonadal malformations that included some intersexual development at low test concentrations, and caused liver abnormalities. Androstene dione reduced reproductive fitness in female specimens, but not male specimens. Chronic exposure to androstene dione did not markedly alter breeding success in both sexes or decrease embryo-larval viability in F1 progeny, in contrast to the effects of E2.

Finally, chronic exposure to methoxychlor delayed development, including slowing the rate of metamorphosis; had a slight affect on the normalcy of larval development; caused skewed sex ratios toward the female gender; and induced gonad, liver, and thyroid abnormalities in juvenile specimens. Furthermore, chronic methoxychlor exposure impaired both female and male reproduction fitness. Increasing concerns over the widespread finding of EDCs in the environment have dramatically increased the need for standardized assays, such as the XLCA, because no other assay of this type is available today.

Publications and Presentations:

Publications have been submitted on this project: View all 2 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 1 journal articles for this project

Supplemental Keywords:

small business, SBIR, amphibian lifecycle, monitoring, endocrine-disrupting chemicals, EDCs, Xenopus, X. tropicalis, 17b-estradiol, E2, androstene dione, methoxychlor, progeny, fertilization, sexual development, larval development, XLCA., RFA, Health, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, POLLUTANTS/TOXICS, Environmental Chemistry, Chemicals, Endocrine Disruptors - Environmental Exposure & Risk, endocrine disruptors, Monitoring/Modeling, Biochemistry, Environmental Monitoring, Biology, Endocrine Disruptors - Human Health, assays, amphibian lifecycle testing, endocrine disrupting chemicals, animal model, sexual development, altered sexual development, modeling, developmental biology, amphibian lifecycle test, ecological models, androstene dione

Progress and Final Reports:
Final Report


SBIR Phase I:

Development and Preliminary Validation of an Amphibian Lifecycle Test Method for Monitoring Endocrine Disruption  | Final Report

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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