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Main Title Novel Amphibian Tier 2 Testing Protocol: A 30-Week Exposure of Xenopus Tropicalis to the Antiandrogen Flutamide.
Author Knechtges, P. L. ; Sprando, R. L. ; Porter, K. L. ; Brennan, L. M. ; Miller, M. F. ;
CORP Author Army Center for Environmental Health Research, Fort Detrick, MD.
Publisher 2007
Year Published 2007
Report Number EPA-IAG-DW-21-93962001-2;
Stock Number ADA462783
Additional Subjects Environmental tests ; Pollutants ; Frogs ; Biochemistry ; Test methods ; Endocrine glands ; Endocrine disruption ; Flutamide ; Screening programs ; Edc(Endocrine-disrupting chemicals)
Library Call Number Additional Info Location Last
NTIS  ADA462783 Some EPA libraries have a fiche copy filed under the call number shown. 07/26/2022
Collation 11p
In 1996, the U.S. Congress mandated the development of a screening program for endocrine-disrupting chemicals (EDCs) using validated test systems. Subsequently, the Endocrine Disruptor Screening and Testing Advisory Committee recommended the development of a standardized amphibian assay for tier 2 testing of EDCs. For that reason, a tier 2 testing protocol using Xenopus (Silurana) tropicalis and a 30-week, flow-through exposure to the antiandrogen flutamide from stage 46 tadpoles through sexually mature adult frogs were developed and evaluated in this pilot study. The endpoints for this study included measurements of frog body lengths and weights, liver weights, ovary/egg mass weights, testicular and ovarian histopathology, plasma vitellogenin levels, and notes on any abnormalities observed at necropsy. Increasing exposure concentrations to flutamide caused significant increases in frogs with no recognizable gonadal tissue and increased body and liver weights in male frogs, whereas the body lengths and weights decreased significantly in female frogs. Important issues must be resolved before a tier 2 amphibian assay can be further developed and validated, including the establishment of baseline values in the controls for the parameters under study; the maintenance, measurement, and timing of exposure concentrations; and the development of additional biomolecular markers of effect. This study demonstrated the feasibility of conducting long-term EDC exposure studies using X. tropicalis.