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Perchlorate affects thyroid function in eastern mosquitofish (Gambusia holbrooki) at environmentally relevant
Carrie M Bradford1, Jacques Rinchard, James A Carr
1The Institute of Environmental and Human Health, Department of Environmental Toxicology, Texas Tech University, Box 41163, Lubbock, Texas 79409-1163, USA.
Environmental Science & Technology
|August 9, 2005
Summary
Perchlorate exposure significantly alters thyroid function in mosquitofish, with histopathology serving as a sensitive biomarker for endocrine disruption even at low environmental concentrations.
Area of Science:
- Environmental Toxicology
- Endocrinology
- Aquatic Biology
Background:
- Perchlorate is an environmental contaminant affecting thyroid function.
- Understanding its impact on aquatic organisms is crucial for ecological health assessments.
Purpose of the Study:
- To investigate the effects of sodium perchlorate on thyroid function in adult mosquitofish.
- To evaluate thyroid histopathology and whole-body thyroxine (T4) levels as indicators of perchlorate exposure.
Main Methods:
- Mosquitofish were exposed to varying concentrations of sodium perchlorate (0-1000 mg/L) for 2, 10, and 30 days.
- Thyroid follicle histology (epithelial height, hyperplasia, hypertrophy, colloid depletion) and whole-body T4 content were assessed.
Main Results:
- Perchlorate exposure increased follicular epithelial cell height, hyperplasia, and hypertrophy, particularly at 30 days.
- Statistically significant changes were observed at concentrations as low as 0.1 mg/L.
- Colloid depletion decreased with increasing perchlorate, contrary to expected thyroid inhibition.
- Whole-body T4 levels decreased after 30 days, but showed less clear dose-response relationships than histopathology.
Conclusions:
- Thyroid histopathology is a sensitive biomarker for detecting thyroid endocrine disruption by perchlorate in mosquitofish.
- Environmentally relevant concentrations of perchlorate can impact thyroid function.
- Histopathological endpoints are more sensitive indicators of perchlorate exposure than whole-body T4 levels.