Fish embryos as teratogenicity screens: a comparison of embryotoxicity between fish and birds.

Early life stage (ELS) toxicity experiments were carried out with zebra fish (Brachydanio rerio) and rainbow trout (Salmo gairdneri) and 10 chemicals used in the rubber industry. Several of these chemicals appeared to be teratogenic. A good correlation (r = 0.95) was found between the 7-day EC50 for zebra fish and the 60-day EC50 for rainbow trout for total embryotoxicity (embryolethality and malformations). The S. gairdneri test appeared to be slightly more sensitive than the test with B. rerio. It is therefore concluded that this short-term test is a good alternative for the long-term test with S. gairdneri. A remarkably good correlation (r = 0.90) was found between the ED50 for chicken embryotoxicity reported in the literature and the EC50 for embryotoxicity for both zebra fish and rainbow trout. This may, among other things, be explained by similarities in embryonic development and the absence of maternal and placental metabolism of the toxicants in tests with eggs of both fish and birds. It may therefore be concluded that both the short-term ELS test with B. rerio and the chicken egg test have the same predictive power for mammalian teratogenicity; i.e., both are suitable screening tests for direct-acting teratogens.