The purpose of the Dominant lethal (DL) test is to investigate whether chemical agents produce mutations resulting from chromosomal aberrations in germ cells. In addition, the dominant lethal test is relevant to assessing genotoxicity because, although they may vary among species, factors of in vivo metabolism, pharmacokinetics and DNA-repair processes are active and contribute to the response. Induction of a DL mutation after exposure to a test chemical indicates that the chemical has affected germinal tissue of the test animal.

This modified version of the Test Guideline reflects more than thirty years of experience with this test and the potential for integrating or combining this test with other toxicity tests such as developmental, reproductive toxicity, or genotoxicity studies; however due to its limitations and the use of a large number of animals this assay is not intended for use as a primary method, but rather as a supplemental test method which can only be used when there is no alternative for regulatory requirements.