From the viewpoints of development animal welfare and cost, various alternative methods for experimental animals have been developed and used for safety assessment of chemicals. They are beginning to be applied to the reproductive and developmental toxicity assessment as well. The revised International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines on S5(R3) "Detection of Reproductive and Developmental Toxicity for Human Pharmaceuticals" mentioned alternatives in embryo-fetal development tests. One of these methods is an evaluation method using zebrafish (ZF) embryos. The ZF embryo test can be used specifically for screening since it has advantages as follows: easy to observe because of the transparent nature of the embryo and larvae, small amounts of the compound required for performing the test, and study period of about a week.
OECD Test Guidelines in the environmental impact assessment of chemicals such as TG212 and TG236 have widely utilized ZF-embryos. When chemicals are exposed to ZF, the quality and selection of fertilized eggs are important to assess toxicity appropriately using ZF embryos, and it is usually necessary to select a method of exposure that suits the properties of the chemical. However, international standardization of test methods and evaluation criteria has not yet been established in this test. It may be difficult to interpret the results in evaluating the same substance with different exposure methods, such as the presence or absence of chorions and solvent concentrations in the previously reported.
The analytical results of background data of the control in the developmental toxicity test using ZF embryos in our laboratory are introduced.
In addition, to study whether differences in exposure methods affect the development of morphological abnormalities, we also report the results of tests conducted using the teratogenic chemical substances.