Frog Embryo Teratogenesis Assay - Xenopus (FETAX)
The Frog Embryo Teratogenesis Assay - Xenopus (FETAX) is a 96-hour
whole-embryo developmental toxicity test that uses early-stage embryos of the South African clawed frog (Xenopus laevis)
to measure the effects of chemicals on mortality, malformation, and growth inhibition. It was proposed as a screening assay
to identify potential human teratogens and developmental toxicants.
In May 1998, the U.S. EPA requested that ICCVAM evaluate FETAX. ICCVAM and its
developmental toxicity working group subsequently agreed to
further consider the method. An expert panel meeting in May 2000 reviewed
the current status and future directions for research and development of the method.
The panel concluded that FETAX was not sufficiently validated or optimized for
regulatory applications. The panel recommended further standardization of the
assay to improve variability and recommended expanding the number of endpoints
assessed to increase the performance of FETAX for identifying developmental toxicants.
Related FETAX Documents:
- Hoke RA, Ankley GT. 2005. Critical Review:
APPLICATION OF FROG EMBRYO TERATOGENESIS ASSAY-XENOPUS TO ECOLOGICAL RISK ASSESSMENT.
Environmental Toxicology and Chemistry 24(10):2677-2690.
This review provides an evaluation and critique of the current FETAX
protocol from two perspectives: Practical considerations relative to conducting the test and sensitivity of the assay (and associated
endpoints) compared to tests with other species.
- Meeting Minutes: May 16-18, 2000
-
Background Review Document: Frog Embryo Teratogenesis Assay -- Xenopus (FETAX) [March 10, 2000 - HTML]
Related Regulations and Guidelines:
- American Society for Testing and Materials
The following Standards can be purchased online at the
ASTM Store.
Order by mail: ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959 / USA
- ASTM E691-99: Standard Practice for Conducting an Interlaboratory Study to Determine the
Precision of a Test Method (10 May 1999)
- ASTM E1439-98: Standard Guide for Conducting the Frog Embryo Teratogenesis
Assay-Xenopus (FETAX) (10 June 1998)
- U.S. EPA Office of Water
- U.S. EPA Office of Prevention, Pesticides and Toxic Substances
Health Effects Test Guidelines
(Documents may also be found on
Testing Guidelines Search Page)
- 870.3550 Reproduction/developmental toxicity screening test [PDF]
- 870.3650 Combined repeated dose toxicity study with the reproduction/developmental toxicity screening test [PDF]
- 870.3700 Prenatal developmental toxicity study [PDF]
- 870.3800 Reproduction and fertility effects [PDF]
- OECD Test Guidelines for Developmental Toxicity
(Available from Source OECD -
View List)
- 414: Prenatal Developmental Toxicity Study (Updated Guideline, adopted 22nd January 2001)
- 421: Reproduction/Developmental Toxicity Screening Test (Original Guideline, adopted 27th July 1995)
- 422: Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Toxicity
Screening Test (Original Guideline, adopted 22nd March 1996)
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