Fish acute embryo test for evaluation of thyroid hormone system disruption

Commonly used acronym: FET for THSD

Scope of the method

The Method relates to
  • Animal health
  • Environment
  • Human health
The Method is situated in
  • Basic Research
  • Translational - Applied Research
Type of method
  • In vivo
Used species
Currently mainly zebrafish (Danio rerio) but other species are possible such as fathead minnow
Targeted organ system or type of research
thyroid hormone system


Method keywords
  • Endocrine disrupting chemicals
  • Fish embryo
  • zebrafish
  • Hormone responsiveness
Scientific area keywords
  • regulatory toxicology
  • aquatic toxicity
  • human health
  • Environmental health
Method description

Thyroid hormone system disruption (THSD) has detrimental effects on both human and environmental health. As a rising number of chemicals are reported to interfere with the thyroid hormone system, there is an increasing need for fast and reliable evaluation methods to test for THSD. Currently, established in vivo endocrine disruptor tests are labour and time intensive and require the use of mostly mammalian laboratory animals. In the current method the fish embryo acute toxicity test (OECD test guideline 236), which determines lethality, is being adapted to include THSD-responsive endpoints (thyroid hormone levels, swim bladder inflation and eye development). In this test, the fish embryos are continuously exposed to a test chemical and development is monitored daily. At the end of the exposure, lethal and sublethal effects as well as effects on swim bladder inflation and eye development are assessed and samples are collected for thyroid hormone measurements. The test duration is limited to the non-protected life stages of fish and thus supports reducing the number of laboratory animals.

Lab equipment
  • - Fish breeding setup,
  • - incubator with light/dark cycle for embryo exposure,
  • - stereomicroscope for observation of embryos.
Method status
  • Currently submitted for further validation by an external party (e.g. OECD, EURL ECVAM,…)

References, associated documents and other information

  • - Knapen et al. (2020) Environ. Sci. Technol. 2020, 54, 8491−8499;
  • - Stinckens et al. (2018) Aquatic Toxicology 200: 1–12;
  • - Nelson et al. (2016) Aquatic Toxicology 173 (2016) 192–203;
  • - Stinckens et al. (2016) Aquatic Toxicology 173 (2016) 204–217;
  • - Cavallin et al. (2017) Environmental Toxicology and Chemistry, Vol. 36, No. 11, pp. 2942–2952, 2017;
  • - Baumann et al. IJMS. Vol 20, Issue 7, DOI 10.3390/ijms20071543;
  • - Baumann et al. 2016. Aquat. Toxicol. Vol. 172 Pp 44-55. DOI10.1016/j.aquatox.2015.12.015;
  • - Gölz et al. Environ Toxicol Chem. 2022 Nov;41(11):2632-2648. doi: 10.1002/etc.5452.