Applicability of zebra fish teratogenicity assay for surfactants

Summary

Available toxicological data demonstrate that surfactants that are typically used in consumer products like detergents, do not impact human reproductive health. Nonetheless, the European REACH Regulation still requires the evaluation of reproductive toxicity of chemicals as a default if the chemical is supposed to be registered for yearly tonnages of 10 t and higher. Currently, such evaluation can only be performed in rodent studies, which contradicts with the general ambition of reducing the number of animal tests for chemical safety evaluation.
The zebra fish teratogenicity assay might provide an option to preselect chemicals for their potential reprotoxic behavior, and it could thereby help to inform whether the registration and related testing of a chemical should be pursued. Since this test involves zebra fish fetuses up to 4 days post fertilization, it is considered a more humane type of study compared to the current tests in rodents. However, it is currently not known if the applicability domain of the zebra fish teratogenicity assay also includes surfactants.

Background

The zebra fish teratogenicity assay is an in vitro model derived from ecotoxicology guideline tests, which uses fetuses up to 4 days post fertilization in order to predict human teratogenicity. Some pilot tests with surfactants have indicated that the test might not be suitable for this substance class, as they easily induce lethality, making it difficult to distinguish lethality from teratogenicity.
The objective of the project was to review the current state-of-the-art of the zebra fish teratogenicity assay in order to have a better understanding of its potential and limitations, and to assess the applicability for testing surfactants.

Outcome of research

A literature search retrieved 1447 entries related to ZETA which were further reduced to 66 entries of high relevance for the scope of this project. [….]
Based on the information retrieved, it is concluded that the ZETA can be applicable for testing surfactants. However, some data gaps regarding specific methodological aspects remain and require clarification before this test can be employed for the evaluation of teratogenic properties of surfactants. Furthermore, it remains unclear which influence physicochemical properties of the surfactants, e.g. their potential to form micelles, have on the outcome of the test.

Relevant references

Carolina Di Paolo, Sebastian Hoffmann, Hilda Witters, Juan-Carlos Carrillo: Minimum reporting standards based on a comprehensive review of the zebrafish embryo teratogenicity assay. Regulatory Toxicology and Pharmacology, Volume 127, December 2021, 105054. Available for download here: https://www.sciencedirect.com/science/article/abs/pii/S0273230021001951?via%3Dihub