The feasibility of the zebrafish embryo as a promising alternative for acute toxicity test using various fish species: A critical review

With the European Union's restrictions on toxicity tests using vertebrates and the issue of the Organization for Economic Co-operation and Development test guideline 236, the fish embryo test (FET) has become a promising alternative to acute fish toxicity test (AFT), with zebrafish embryos being used the most. A large number of studies showed zebrafish FET correlated well with zebrafish AFT, yet its representativeness for other fish species is still under evaluation. In this review, toxicity data of zebrafish FET were summarized and compared with AFT using zebrafish and other test species in various countries, such as fatheadmin now(Pimephales promelas), bluegill sunfish (Lepomis macrochirus), and Chinese rare minnow (Gobiocypris rarus). Previous findings of good relationship between zebrafish FET and AFT were confirmed, with a significant relationship between the median lethal and effect concentrations (LC50 and EC50) in FET and AFT LC50 for 87 chemicals (log (LC50(AFT)) = 1.00 x log (LC50(FET)) - 0.0829, p < 0.0001). Since embryo lethality generally occurs at chemical concentrations much higher than their environmentally relevant concentrations and involves in multiple modes of action, the EC50s gradually become the preferred FET parameters. Therefore, the use of FET EC50 for predicting fish toxicity was also evaluated. Interestingly, we found that the zebrafish FET toxicity data well predicted AFT of G. rarus that is native AFT model species in China, yet its corresponding FET is still immature. This highlights the zebrafish embryo test would serve as a good alternative for AFT across fish species. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Zebrafish embryo test shows promising potential as an alternative to acute fish toxicity test, with good correlation to acute fish toxicity test in predicting fish toxicity. It also demonstrates good predictive ability for rare minnow species in China.